Automotive Engineering Laboratory

Transcript

AEN-314 AUTOMOTIVE ENGINEERING LABORATORY AUTOMOTIVE LABORATORY 1 1. INTRODUCTION Internal combustion engines are devices that generate work using the products of combustion as the working fluid rather than as a heat transfer medium. To produce work, the combustion is carried out in a manner that produces high-pressure combustion products that can be expanded through a turbine or piston. The engineering of these high pressure systems introduces a number of features that profoundly influence the formation of pollutants. There are three major types of internal combustion engines in use today: (1) the spark ignition engine, which is used primarily in automobiles; (2) the diesel engine, which is used in large vehicles and industrial systems where the improvements in cycle efficiency make it advantageous over the more compact and lighter-weight spark ignition engine; and (3) the gas turbine, which is used in aircraft due to its high power/weight ratio and also is used for stationary power generation. Internal combustion engines are most commonly used for mobile propulsion in vehicles and portable machinery. In mobile equipment, internal combustion is advantageous since it can provide high power-to-weight ratios together with excellent fuel energy density. Generally using fossil fuel (mainly petroleum), these engines have appeared in transport in almost all vehicles (automobiles, trucks, motorcycles, boats, and in a wide variety of aircraft and locomotives). Aim of this experiment is to determine performance characteristics of a four stroke diesel engine. 1.1. The Four Stroke Diesel Engine The four-stroke diesel engine is similar to the four stroke gasoline engine. They both follow an operating cycle that consist of intake, compression, power, and exhaust strokes. They also share similar systems for intake and exhaust valves. A diesel engine is much more efficient than a gasoline engine, such as the diesel engine does not require an ignition system due to the heat generated by the higher compression, the diesel engine has a better fuel economy due to the complete burning of the fuel, and the diesel engine develops greater torque due to the power developed from the high-compression ratio. 2 AUTOMOTIVE LABORATORY 1 Intake Stroke: The piston is at top dead center at the beginning of the intake stroke, and, as the piston moves downward, the intake valve opens. The downward movement of the piston draws air into the cylinder, and, as the piston reaches bottom dead center, the intake valve closes. Figure 1. Induction stroke Compression Stroke: The piston is at bottom dead center at the beginning of the compression stroke, and, as the piston moves upward, the air compresses. As the piston reaches top dead center, the compression stroke ends. Figure 2. Compression stroke Power Stroke: The piston begins the power stroke at top dead center. At this point, fuel is injected into the combustion chamber and is ignited by the heat of the compression. This begins the power stroke. The expanding force of the burning gases pushes the piston downward, providing power to the crankshaft. The diesel fuel will continue to bum through the entire power stroke (a more complete burning of the fuel). The gasoline engine has a power stroke with rapid combustion in the beginning, but little to no combustion at the end. 3 AUTOMOTIVE LABORATORY 1 Figure 3. Power stroke Exhaust Stroke: As the piston reaches bottom dead center on the power stroke, the power stroke ends and the exhaust stroke begins. The exhaust valve opens, and, as the piston rises towards top dead center, the burnt gases are pushed out through the exhaust port. As the piston reaches top dead center, the exhaust valve closes and the intake valve opens. The engine is now ready to begin another operating cycle. Figure 4. Exhaust stroke The diesel internal combustion engine differs from the gasoline powered Otto cycle by using a higher compression of the fuel to ignite the fuel rather than using a spark plug ("compression ignition" rather than "spark ignition"). In the diesel engine, air is compressed adiabatically with a compression ratio typically between 15 and 20. This compression raises the temperature to the ignition temperature of the fuel mixture which is formed by injecting fuel once the air is compressed. The ideal air-standard cycle is modeled as a reversible adiabatic compression followed by a constant pressure combustion process, then an adiabatic 4 AUTOMOTIVE LABORATORY 1 expansion as a power stroke and an isovolumetric exhaust. A new air charge is taken in at the end of the exhaust, as indicated by the processes a-e-a on the diagram. Figure 5. Air standard diesel engine cycle The main difference between the Diesel and Otto engine is burning of the fuel. In a Gasoline engine, the air/fuel mixture enters the cylinder and creates a stoichiometric homogeneous mixture, which is ignited and the flame travels from the spark and outwards to the liner. In the Diesel engine, air enters the cylinder, fuel is injected, self-ignites and burns with a diffusion type of combustion. The Diesel has: • Higher compression ratio (higher thermodynamic efficiency, no knock) • No throttle (no pumping losses, power ∼ fuel) • Combustion is always lean (lower heat losses, higher efficiency) • More flexible about choice of fuel 5 AUTOMOTIVE LABORATORY 1 2. EXPERIMENTAL CALCULATIONS 2.1 Torque and Power Output The engine torque was measured by the help of a hydraulic dynamometer. The power output is calculated from the torque by multiplying by the angular velocity in radians per second. Because the dynamometer acts as a brake on the engine, the power at the output shaft is referred as the “Brake Power” (PB). where: (1) is brake power (W), N is speed (rpm), is torque (Nm). 2.2. The Performance of an Ideal Engine One aspect of engine testing is to determine how the torque and brake power vary with engine speed. To interrupt the results from a real engine, it is necessary to establish the maximum performance that can be expected from an ideal engine, which converts the energy contained in the fuel into mechanical work without loss. The power output depends on the rate where the fuel can be burned. For complete combustion, the fuel must be mixed with air in the correct chemical proportions. If sufficient oxygen is available, a hydrocarbon fuel can be completely oxidized. The carbon in the fuel is then converted to carbon dioxide CO2, and the hydrogen to water H20. The amount of air drawn into the cylinder that determines how much fuel can be burned during each cycle. Ignoring the volume occupied by the fuel, the volume of air induced into the cylinder during each cycle is ideally equal to swept volume. If the air drawn in from atmosphere at a density ( ), then: (2) where: is density of air (kg/m3) is swept volume (m3) The air consumption rate is given by formula: (3) where: is air consumption rate (kg/s), N is speed (rpm), 6 AUTOMOTIVE LABORATORY 1 n=1 for two stroke engine n=2 for four stroke engine Assuming complete combustion, heat generated per unit mass of fuel is equal to the calorific values, H. This is typically 42000 kJ/kg for petrol, 39000 kJ/kg for diesel fuel. The rate, Q at which heat is supplied to the engine, is given by: (4) All the energy could be converted into mechanical power, the power output would be: (5) Expressing the fuel consumption rate in term of the other variables given by formula 3,4,5 Ideal Brake Power Output: (6) 2.3. Brake Mean Effective Pressure and Specific Fuel Consumption Another measure of engine efficiency are brake mean effective pressure (bmep) and specific fuel consumption (sfc). (kPa) (7) (g/kWh) (8) Specific fuel consumption is a useful measure of engine performance because it relates directly to the economy of an engine. It enables the operator to calculate how much fuel is required to produce a certain power output for a certain power output for a certain length of time. So the specific fuel consumption can be used to estimate the economic performance of the different engine type. 2.4. Thermal Efficiency In thermodynamics, the thermal efficiency ( ) is a dimensionless performance measure of a device that uses thermal energy, such as an internal combustion engine, a steam turbine or a steam engine, a boiler, a furnace, or a refrigerator for example. The thermal efficiency is defined as: (7) When we expand the terms in , we can obtain following equation: (8) where; 7 AUTOMOTIVE LABORATORY 1 α is the cut-off ratio (ratio between the end and start volume for the combustion phase) r is the compression ratio ( ) is ratio of specific heats ( ) 2.5. Heat Loss in Exhaust An estimate heat loss to the exhaust can be made by measuring the difference between the exhaust and ambient temperatures (25 oC) and assuming a typical value of 1 kJ/kg.K for the specific heat of the exhaust gases. 3. THE ENGINE TEST RIG A commercial four cylinders, four stroke, naturally aspirated, water-cooled direct injection compression ignition engine with a 89 kW maximum power at 3200 rpm engine speed and has 295 Nm maximum torque at 1800 rpm engine speed is going to be used to conduct engine performance test. Technical specifications of engine were presented in Table 1. Table 1. Technical specifications of the test engine 8 AUTOMOTIVE LABORATORY 1 Figure 6. The engine test rig 3.1.Measuring Torque The engine torque was measured by the help of a hydraulic dynamometer. S type load cell is used to measure the torque of dynamometer (Stainless steel which has a sensivity of 1/3000) Dynamometer control unit was used for receiving and collecting all the data that was used by the system. Table 2. Technical specifications of the dynamometer 3.2.Measuring Speed The speed sensor used to detect prime mover speed is the magnetic pickup (MPU). When a magnetic material (usually a gear tooth driven by the prime mover) passes through the magnetic field at the end of the magnetic pickup, a voltage is developed. The frequency of 9 AUTOMOTIVE LABORATORY 1 this voltage is translated by the speed into a signal which accurately depicts the speed of the prime mover. 3.3. Measuring Exhaust Gas Temperature Exhaust gas temperature is measured by a thermocouple. The thermocouple is located in the exhaust pipe closed to the cylinder block of the engine. 3.4. Fuel Measurement Fuel quantity is measured in every 5 seconds by a load cell unit. Then, fuel consumption (g/s) is calculated with the aid of a control unit. 4. RESULTS and DISCUSSIONS 1) Plot bmep, torque, brake power, specific fuel consumption and exhaust temperature versus engine speed. 2) Plot ideal and actual power output versus engine speed. Discuss the differences. 3) Discuss the all graphs. 4) Discuss the differences between diesel and gasoline engine. 5) Derive thermal efficiency of diesel engine. m (g/s) (g/s) Torque PB PB,ideal bmep Sfc Thermal Heat (Nm) (kW) (kW) (kPa) (g/kWh) efficiency loss in exhaust 10 AUTOMOTIVE LABORATORY 1 11 AUTOMOTIVE LABORATORY 1 12 AUTOMOTIVE LABORATORY 1 13 AUTOMOTIVE LABORATORY 1 14 AUTOMOTIVE LABORATORY 1 15 AUTOMOTIVE LABORATORY 1 16 AUTOMOTIVE LABORATORY 1 17 AUTOMOTIVE LABORATORY 1 18 AUTOMOTIVE LABORATORY 1 19 AUTOMOTIVE LABORATORY 1 20 AUTOMOTIVE LABORATORY 1 21 AUTOMOTIVE LABORATORY 1 22 ENERGY LABORATORY LIFT AND DRAG MEASUREMENTS OF AN AIRFOIL 1. PURPOSE The purpose of this experiments is to measure the drag and lift forces exerted on an airfoil model with varying angle and to pressure distributions around this airfoil. 2. INTRODUCTION A body immersed in a fluid stream will experience forces due to action of the fluid stream. It is customary to choose one axis parallel to the free stream and downstream. The force on the body along this axis is called drag force. A second and important force is perpendicular to the drag and usually performs a useful job, such as bearing the weight of the body. It is called lift force. Third component is the side force. Airfoil wing is shown in figure 1. The angle between the free stream and the chord line is called the angle of attack . The lift force FL, and drag force FD, vary with this angle. The chord of an airfoil is the straight line joining the mean thickness line between the airfoil leading edge and trailing edge. When the airfoil has a symmetric section, the mean line and the chord line both are straight lines and they coincide. An airfoil with a curved mean line is said to be chambered. Leading edge FL FD Chamber Line  b (Span) t Trailing edge c (Chord) Figure 1. Airfoil wing 3. THEORY AND EQUATIONS The drag force is the component of force on a body acting parallel to the direction of motion. The drag force FD on an airfoil body depends upon thickness t, viscosity of fluid , air flow velocity U, the density of the fluid . When the angle of attack is equal to zero, the drag coefficient CD is written as CD  FD U2A f  f (Re) (1) The frontal area Af of the airfoil is (Af=t b). The number 1/2 is inserted and hence the drag coefficient CD is defined as 23 ENERGY LABORATORY CD  FD 1 2 U A f 2  f  Re  CD  f  Re (2) The lift coefficient can be defined as; CL  FL 1 U2A p 2  f  Re  C L  f  Re (3) Where Ap is the planform area. The lift and drag coefficient for an airfoil are functions of both Reynolds number and angle of attack, . Hence, CL or CD=f(Re,). The maximum projected area of the airfoil is used to define lift and drag coefficient. These areas are; - Frontal area: thickness x span (Af =t.b). - Planform area: span x chord length (Ap= b.c). PS PT C.V Figure 2. Velocity profiles around on airfoil Measurement of the air flow velocity: Mean velocity, U, can be found from the stagnation and static pressures. PT=PS+PD (4) Here PD is the dynamic pressure PD=PT-PS PD  (5) 1 air U2 2 1  U2  PT  PS 2 air (6)  U 2( PT  PS )  air (7) 24 ENERGY LABORATORY Re  UD h air  (8) Dh  4 AC TC (9) Where FD = Drag Force (N) PS = Static Pressure (N/m2) CD = Drag Coefficient U = Mean Velocity (m/s) FL = Lift Force (N) Re = Reynolds Number CL = Lift Coefficient air = Air density (kg/m3) PT = Stagnation Pressure (N/m2)  = Dynamic Viscosity of Air (N/ms) 2 PD = Dynamic Pressure (N/m ) Dh = Hydraulic Diameter (m) 2 AC = Cross-sectional Area of Channel (m ) TC = Periphery of channel (m) H= Channel Height (m) B= Channel Width (m) 4. PRESSURE MEASUREMENTS There are 20 pressure tappings around the airfoil. A computer is used to command the entire equipment, including processes such as channel selection and the simultaneous collection and analysis of the data. Pressure outlets from the airfoil are connected to scanning box. Pressure lines from the scanning box are connected to fittings at the rear of micromanometer. Pneumatic pressures are applied to both sides of the micromanometer’s diagram. The pneumatic pressure difference is transferred into a binary-coded-decimal (BCD) output signal, which is fed to the computer by the micromanometer. Consequently, the microcomputer collects a pre-selected number of samples for each reading in quick succession memorized and then analysed. Finally the processed results are printed on a line printer. The dynamic pressure PD at the entrance of test chamber, the static pressures around the airfoil, the lift force FL and drag force FD are measured by the computer controlled data acquisition system. These results are processed and plotted by the computer. For these purposes, procedures listed below must be followed. - Press F1, F1 so that Printer Status is DATA - Ensure printer paper is at start of page and switches 1 and 3 on. - Press F1, F2 and press N - Enter a new file name (for example afoil.out) - Press ENTER - Press Y - Ensure file name appears on Test Status - Press F2, F1. Select SCAN20.TSF and press ENTER - Press P ENTER ENTER -Test status says PROG PAUSE until F3 pressed which will then print out the data and next angle setting is shown. If further data is required move model to the next position and press F3. 25 ENERGY LABORATORY - To print out graph, press F3, F4, wait - Press ESC ESC ESC Back Slash (/) - Press F (File), R (Retrieve) - Select AFOIL2.WQ2 (always this file name), press ENTER - Select your out file (for example afoil.out), press ENTER - Press F10 to view graph - Press ESC, set printer paper to new page - Press Back Slash (/), P (Print), G (Graph Print), G (Go) and take the list of data and graph of pressure distributions around the airfoil. 5. DESCRIPTION OF EXPERIMENTAL SET UP Schematic diagram of the set up is shown in figure 3. The mean velocity is measured by the Pitot-static tube that is placed in the middle of channel. The airfoil body is placed behind the Pitot-static tube and it can be rotated with a model holder. The drag and lift forces are recorded from the main display. From the above measurements; the mean velocity U, the drag coefficient CD, and the lift coefficient CL can be calculated. 6. CONSTANT VALUES t= 19 mm b= 297 mm f=780 kg/m3 c= 152 mm air=1.2 kg/m3 H=0.3 m B=0.35 m Calculation of density of air - Measure the atmospheric pressure and room (air) temperature. - Calculate the air density air  P RT where R: Ideal gas constant. 7. PERFORMING THE EXPERIMENT For performing the experiment, procedures listed below must be followed. 1- Push the start button on. 2- Wait for 15 minutes for the configuration of the main display from which the lift and drag forces can be recorded manually 3- Follow the procedure list given in section 4 to measure and plot the pressure distribution around the airfoil. 4- Record the total pressure PT and the static pressure PS levels from the 24 tube manometer 5- Rotate the airfoil to change the angle from the model holder. 6- Record; FD, FL from the main display. 7- Now, the experiment is over. Push the stop button off. 8. PREPARATION OF THE REPORT 1- Purpose of the experiment, experimental methods, and experimental set up must be introduced briefly. 2- The required values such as, U, CD, CL, and Re must be calculated. 3- The obtained results must be presented as tables and graphics. 4- Plot CD - Re, CL - Re, CD - , CL - , and CD - CL. 26 ENERGY LABORATORY 5- Plot pressure distributions around the airfoil. 6- Discuss the results. Table of results  U (m/s) PT PS PD FL FD (m) (m) (m) (N) (N) Re CL CD 0 2 4 6 8 10 12 14 16 18 20 4 8 1 5 10 3 6 2 9 7 1- Diffuser 2- Model holder 3- Static Pressure Tapping 6- Button (On-Off) 7- 20 way scanning box 8- Pitot-static tube 4- Total Pressure tube 5- 24 Tube manometer 9- Stand level on assembly 10- Silencer Figure 3. Schematic diagram of the experimental set-up 27 MANUFACTURING LABORATORY IMPACT TEST THEORY The impact test is designed to have a sound insight into the mechanical properties of metals under the conditions conductive to brittle fracture. In the impact test, the energy required for the rupture of the sample under dynamic loading is to be determined. A notched material which displays ductile behavior in a simple tension test may behave like a brittle material under impact loading. This is especially the case in temperatures below the room temperature. The impact test on notched samples is performed in two ways as shown in Figure 1. Figure 1. Type of applied load and test apparatus [Ref 1] The samples are notched in V and U shapes. The aim is to form a stress concentration at the tip of the notch, and to determine the resistance of the material to dynamic forces. A notched sample is said to break in a “brittle manner” if it breaks before deforming plastically. In brittle fracture, the fracture surface would be smooth. If, on the other hand, the sample shows some plastic deformation before fracture, it is said to break in a “ductile manner” and the fracture surface would then be rough, having extrusions and intrusions on it. An impact test performed on a material would yield more meaningful results if it is done at various temperatures. A generic plot of such results is shown in Figure 2. As it can be seen from Figure 2., the lower the temperature, the less is the materials resistance to impact loading. (Ref 1: http://www.mak.etu.edu.tr/dersler/mak207l/mak207l/Darbe%20deneyi.doc) 28 Rupture Energy MANUFACTURING LABORATORY T1 T2 Temperature Figure 2. The Graph of Material’s Resistance To Impact Loading As A Function of Temperature The (T1-T2) interval in which the resistance drops drastically is called “Transition Interval”. At temperatures below T1 the material behaves in a brittle manner; cracks form and propagate very fast. At temperatures above T2, the material is ductile; it first deforms plastically, and therefore the crack formation is inhibited and cracks propagate in a much slower manner. Within the transition interval both ductile and brittle behaviors are observed. The tests are usually performed at above certain temperature T (transition temperature) which is determined according to the following criteria. 1. Rupture Energy: Usually the temperature corresponding to (2-3 kgm) of energy is assumed to be the transition temperature. 2. The Fracture Surface: The T value which gives 50% crystallinity on the surface can be taken as the transition temperature. 3. Transverse Contraction After Fracture: The T value which provides a 1% transverse contraction at the crack tip is assumed to be the transition temperature. The transition temperature constitutes an important material design criterion in engineering applications. Materials with low transition temperature are usually preferred. The transition temperature varies from material to material. It can also vary for the same material depending on the factors such as chemical composition, grain size, microstructure and cold working. PERFORMING THE EXPERIMENT 1. The sample is prepared with the dimensions as specified in Figure 3. 0.25 mm 8 mm 10 mm Figure 3. Standardized Notched Sample 29 10 mm 45o MANUFACTURING LABORATORY 55 mm 2. 3. 4. 5. The sample is placed on the stand of the instrument. A pendulum is released down from a known height. The rupture energy is read from the instrument. The fracture surface is examined. RESULTS AND DISCUSSION 1. Determine the type of fracture (brittle or ductile) by examining the fracture surface. 2. The transition temperature curves of two different types of steel are given in Figure 4. Which one of the two types of steel would you choose to be used in a machine element if the machine is to be operated at; a.) room temperature, b.) –20 oC ?. Explain the reasons. Energy (ft-lb) A 6 0 4 0 B 20 0 -62 -40 -18 4 27 Temperature, 0C Figure 4. Two Transition Temperature Curves 3. Altough the area under stress-strain curve in tensile test gives the energy value which is called thougness of material, why do we use the impact test? 4. Why do we embed notched side of the sample as reverse position according to applied impact point on the sample surface? TEST RESULTS Sample No 1 2 3 0 0 C kgm kgm kgm C kgm kgm kgm 0 C kgm kgm kgm Impact Energy = Test data x g (where g is gravity acceleration) [Joule] Impact Toughness = Impact Energy/Cross-sectional Area [Joule/cm2] 30 MANUFACTURING LABORATORY EXPERIMENT FOR TENSILE MEASUREMENT INTRODUCTION The tensile test is a fundamental mechanical test for material properties which are used in engineering design, analysis of structures, and materials development. Using the data generated from a tensile test we can plot a stress-strain curve, which characterizes a material’s mechanical performance. The test is used to directly or indirectly measure the most important material properties such as yield strength, tensile strength, elastic modulus, elongation, resilience, and toughness. Table 1. Common Material Tests and Properties or Characteristics Found Test Type Characteristics Measured Yield Strength, Ultimate Strength, Modulus of Elasticity, Ductility, Resilience, Toughness, Tensile Test Strain Hardening Compression Test Yield Strength, Modulus of Elasticity Torsion Test Modulus of Rigidity, Forgeability Bending Test Modulus of Rupture, Modulus of Elasticity, Fracture Strength Hardness Test Hardness, Resilience, Toughness, Ultimate Strength Fatigue Test Endurance Limit Creep Test Creep Rate, Heat Sensitivity Impact Test Toughness, Notch Sensitivity, Transition Temperature OBJECTIVES The purpose of this experiment is to analyze tensile strengths and also learn how the samples react when forces are applied. These experimental results are important for the characterization of the mechanical properties and performance of materials. Parameters such as Young’s modulus, E, the elastic limit, y, and the ultimate stress, u, are defined in terms of the results of a uniaxial test like the ones the student will perform in this lab. BRIEF BACKGROUND Stress and Strain: Consider the cylinder body to which a force F is applied at both ends in Figure 1. The cylinder will elongate in the direction of the load, and the cross-sectional area A will be decreased in proportion to the extension because of the conservation of matter. F A0 L0 L A F Figure (a) 1. Response of a cylinder (b) after the load is applied Figure 2. Load versus elongation diagram 0-A: ‘Hookian Behaviour’ – in region O-A a linear relationship exists between load and extension. O is the point of no load, an A is known as the ‘limit of proportionality’ up to load at position A. Most materials are designed to operate in this region. A-B: Further extension beyond A is not proportional, but still elastic to position B. Position B is known as the ‘elastic limit’. 0 – A is elastic. B-E is plastic. B-C: Few materials exhibit B-C. The material shown doing this has yielded to the force. Between B and C (very short) a particular part (weakest part) will start to get thinner quicker than the rest of the material, but not at a rate that you would notice visually. C-D: Plastic extension. 31 MANUFACTURING LABORATORY D-Failure: Necking We define the “engineering stress”, e, as   F e A0 e  N m and the “engineering strain”, e, as L  L0 (unitless, or in m/m). These two parameters, e and e, do not depend on L0 the instantaneous cross-sectional area, A. The change in area with extension is materialdependent (determined by the Poisson’s ratio, , of the material) so we define a different parameter, “true stress”, , as   F . We also define a “true strain”, as   L dL  ln L . L L A L0 0 Notice that, for small strains, both the “engineering” value and the “true” values are the same. The behavior of the specimen changes dramatically at different strains during the test. Initially, the stress is proportional to the strain. The material is said to be elastic in this region and can be described by   E (also known as Hooke’s Law). The constant of proportionality, E (the slope of the line), is known as Young’s Modulus or the Modulus of Elasticity. Eventually, the specimen can sustain no more elastic deformation and other mechanisms begin to dominate the behavior. At the yield stress, plastic (permanent) deformation begins and the slope of the stress-strain curve decreases. This is called work hardening (or strain hardening) and the more the specimen deforms, the smaller the slope. At the ultimate tensile stress, geometric softening starts. The cross-sectional area of the specimen has been reduced to the point that the stress overcomes the work hardening aspect. This effect makes the tensile specimen to be “necking”. Ductile and Brittle Behaviors of Materials In the fact that, there is no ductile or brittle material; there is a ductile or brittle behavior. Ductile behavior: Plastic deformation is observable and specimen absorbs significant energy before rupture. A crack, formed as a result of the ductile rupture, propagates slowly and with the stress is increased. Figure 3. Ductile behavior and ductile rupture’s cross section Brittle behavior: Brittle fracture is characterized by very low plastic deformation and low energy absorption prior to fracture. A crack, formed as a result of the brittle fracture, propagates fast and without increase of the stress applied to the material. The brittle crack is perpendicular to the stress direction. Figure 4. Brittle behavior and brittle fracture 32 MANUFACTURING LABORATORY Specimen Size and Configurations Tensile specimen with circular cross-section and cylindiric ends d 0 = Specimen diameter d 2 = Graded section’s Diameter= 1, 2 d d 1 = Ends diameters = 1, 75 d 0 L v = Slim section’s length = L 0 + d 0 L 0 = First length = 5 d 0 L t = Final length h = Graded sections length = d 0 g = Ends length = d 0 + 5 mm 0 Tensile specimen with circular cross-section and graded ends Tensile specimen for sheet materials Tensile specimen for casting materials. Gage length L0 Thickness Widt h APPARATUS n e c k i  L Loa n Loa Loa d d d Figure 5. Tensile test principle and hydraulic universal testing g machine in our lab. necki ng 0 33 Failu re MANUFACTURING LABORATORY TEST METHODOLOGY In this test, a prepared specimen is axially loaded in tension, and it is pulled until it failures. The applied axial loads and the corresponding deformation of the sample are measured. The stresses and strains are then calculated from these values. 1. Measure and record the original diameter of the specimen(s) and record on your data sheet. Calculate the original (first) cross-sectional area. You can use TENSILE TEST DATA TABLE. 2. Using the center punch, carefully mark the gage length on the specimen. Place the specimen in the anvil of the center punch making sure that the specimen is centered. Strike the arm lightly to ensure that the marks do not go too deep. 3. Select the proper grips for specimens and the Universal Testing Machine. Specimens must be threaded into the grips at least two diameters to prevent thread stripping. Caution must be exercised that the bolts for the threaded grips are properly threaded into the grips. 4. Apply the load slowly. Observe the specimen, record the maximum load and continue loading until failure is reached. Record the failure load, which must be observed from the load dial at the instant of failure. 5. Record the final gage length and the diameter of the specimen at the failure point. Observe and record the type of failure in the specimen. SAFETY: 1. Be careful with your fingers while fixing the specimen to the grippers and aligning the specimen to the second gripper particularly. 2. Keep your distance of at least 1 meter from the machine when the machine is in operation (when load applied to the specimen) 3. There would be a loud noise when the specimen breaks. Be prepared for noise. TENSILE TEST Report no : ……………………………. Date : ……………………………. Student : ……………………………. Group : ……………………………. Measured day, hour: ……………………………. Laboratory teacher: ……………………………. Testing device : ……………………………. Material : ……………………………. DATA TABLE Specimen Size and Geometries For circular cross-sectioned specimen For rectangular cross-sectioned specimen Length Linitial = …………..mm Diameter dinitial = …………..mm Length LFinal = …………..mm Diameter dFinal =…………..mm Load versus Length Changing Load-F Linstantaneous Elongation L [kgf] [mm] [mm] Widthinitial = …………..mm Thicknessinitial = …………..mm WidthFinal = …………..mm ThicknessFinal = …………..mm Load versus Length Changing Load-F Linstantaneous Elongation [kgf] [mm] L [mm] 34 MANUFACTURING LABORATORY 1) Task: Carry out a tensile test on an iron, low carbon steel, copper samples, take necessary measurements & evaluate results 2) Task goals: a)determining basic mechanical properties for a given material, b)sum up the test results and compare it with the standard (material datasheet) 3) Measured and calculated values: Draw a sketch of engineering stress – strain diagram (solid line___), mark in relevant values and name axes. In the same diagram, draw a sketch of true stress – strain diagram (dashed line---). Locate each of these stresses (from experimental data) on the following stress/strain diagram. 4. Calculate the following properties: a. Young’s Modulus (This can be obtained from the slope of the first stage (elastic region) of the Stress vs. Strain plot where it should be linear.) b. Yield Stress  c. Ultimate Stress (Read from graphs) d. Break Stress 5. Indicate the Elastic Region in the - graphic 6. Indicate the Plastic Region in the - graphic 7. Is our specimen brittle or ductile? Why?  QUESTIONS AND DISCUSSIONS: 1. What is Hooke’s Law? 2. What deformation processes are occurring in metals during the tensile test? Explain it considering elastic deformation, plastic deformation, bond stretching, dislocations, reduction in area, ductility, elongation to failure, yield stress, ultimate tensile stress, Hooke’s Law? 3. Explain differences between appearances of breaking surfaces of ductile & brittle materials. 4. Explain differences between - diagrams of ductile & brittle materials 35 MANUFACTURING LABORATORY EXPERIMENT FOR HARDNESS MEASUREMENT INTRODUCTION Hardness is the property of a metal, which gives it the ability to resist being permanently deformed (bent, broken, or have its shape changed), when a load is applied. The greater the hardness of the metal, the greater resistance it has to deformation. This is the usual type of hardness test, in which a pointed or rounded indenter is pressed into a surface under a substantially static load. Hardness measurement can be defined as macro-, micro- or nano- scale according to the forces applied and displacements obtained. Measurement of the macro-hardness of materials is a quick and simple method of obtaining mechanical property data for the bulk material from a small sample. It is also widely used for the quality control of surface treatment processes. However, when concerned with coatings and surface properties of importance to friction and wear processes for instance, the macro-indentation depth would be too large relative to the surface-scale features. Microhardness is the hardness of a material as determined by forcing an indenter such as a Vickers or Knoop indenter into the surface of the material under 15 to 1000 gf (gram-force) load; usually, the indentations are so small that they must be measured with a microscope. Conversions from microhardness values to tensile strength and other hardness scales (e.g. Rockwell) are available for many metals and alloys. There are three types of tests used with accuracy by the metals industry; they are the Brinell hardness test, the Rockwell hardness test, and the Vickers hardness test. Since the definitions of metallurgic ultimate strength and hardness are rather similar, it can generally be assumed that a strong metal is also a hard metal. The way the three of these hardness tests measure a metal's hardness is to determine the metal's resistance to the penetration of a non-deformable ball or cone. The tests determine the depth which such a ball or cone will sink into the metal, under a given load, within a specific period of time. The followings are the most common hardness test methods used in today’s technology: 1. 2. 3. 4. 5. Rockwell hardness test Brinell hardness Vickers Knoop hardness Shore 36 MANUFACTURING LABORATORY OBJECTIVES In this experiment we have used Rockwell Hardness Test and Brinell Hardness Test. ROCKWELL HARDNESS TEST The Rockwell hardness test method consists of indenting the test material with a diamond cone or hardened steel ball indenter. The indenter is forced into the test material under a preliminary minor load F0 usually 10 kgf. When equilibrium has been reached, an indicating device, which follows the movements of the indenter and so responds to changes in depth of penetration of the indenter is set to a datum position. While the preliminary minor load is still applied an additional major load is applied with resulting increase in penetration. When equilibrium has again been reach, the additional major load is removed but the preliminary minor load is still maintained. Removal of the additional major load allows a partial recovery, so reducing the depth of penetration. The permanent increase in depth of penetration, resulting from the application and removal of the additional major load is used to calculate the Rockwell hardness number. HR = E - e F0 = preliminary minor load in kgf F1 = additional major load in kgf F = total load in kgf e = permanent increase in depth of penetration due to major load F1 measured in units of 0.002 mm E = a constant depending on form of indenter: 100 units for diamond indenter, 130 units for steel ball indenter HR = Rockwell hardness number D = diameter of steel ball Rockwell Hardness Scales Scale Indenter Minor Load F0 kgf Major Load F1 kgf Total Load F kgf E Value 120° Diamond cone 10 50 60 100 1/16" steel ball 10 90 100 130 120° Diamond cone 10 140 150 100 120° Diamond cone 10 90 100 100 1/8" steel ball 10 90 100 130 1/16" (1,588 mm) steel ball 10 50 60 130 1/16" (1,588 mm) steel ball 10 140 150 130 1/8" (3,175 mm) steel ball 1/8" (3,175 mm) steel ball 1/4" (6,3 mm) steel ball 1/4" (6,3 mm) steel ball 1/4" (6,3 mm) steel ball 1/2" (12,7 mm) steel ball 1/2" (12,7 mm) steel ball 1/2" (12,7 mm) steel ball 10 10 10 10 10 10 10 10 50 140 50 90 140 50 90 140 60 150 60 100 150 60 100 150 130 130 130 130 130 130 130 130 A B C D E F G H K L M P R S V 37 Typical Application of Rockwell Hardness Scales Cemented carbides, thin steel and shallow case hardened steel Copper alloys, soft steels, aluminium alloys, malleable irons, etc Steel, hard cast irons, case hardened steel and other materials harder than 100 HRB Thin steel and medium case hardened steel and pearlitic malleable iron Cast iron, aluminium and magnesium alloys, bearing metals Annealed copper alloys, thin soft sheet metals Phosphor bronze, beryllium copper, malleable irons Aluminium, zinc, lead Soft bearing metals, plastics and other very soft materials MANUFACTURING LABORATORY RESULTS: Collect two or three readings and calculate an average value. Material Data HRC HRC1 =64 HSS HRC2 =61 H RC Average  H RC1  H RC 2  H RC3 =62,6 HRC 3 HRC3 =63 H RC Average  Your Measurement-I H RC Average  Your Measurement-II H RC1  H RC 2  H RC3 3 H RC1  H RC 2  H RC3 3 Hardness reporting: 63 HRC where 63 is the measured value, ‘H’ – hardness test, ‘R’ – Rockwell test, or other test type, ‘C’ – C scale test. Advantages of hardness test are cheaper and easier test than tensile testing, can be performed in the field, can be performed on large specimen. THE BRINELL HARDNESS TEST The Brinell test consists of applying to a metal surface a known load through a hardened steel ball of known diameter. The diameter of the resulting permanent impression in the metal is measured. The Brinell hardness number is taken as the quotient of the applied load divided by the area of the surface of the impression. Charts are available giving the Brinell hardness number corresponding to the various diameters of impressions for both the standard 3000 and 500-kgf loads. This makes it unnecessary to calculate for each test the value of the Brinell hardness number by means of the formula. On tests of extremely hard metals a tungsten carbide ball is substituted for the steel ball. Compared to the other hardness test methods, the Brinell ball makes the deepest and widest indentation, so the test averages the hardness over a wider amount of material, which will more accurately account for multiple grain structures and any irregularities in the uniformity of the material. This method is the best for achieving the 38 MANUFACTURING LABORATORY bulk or macro-hardness of a material, particularly those materials with heterogeneous structures. (a) (b) (c) Figure. (a) Brinel Hardness Tesing Device (b) Microscope (1 division=0,05mm) (c) Schematic test process where; HB = the Brinell hardness number , F = the imposed load in kgf , D = the diameter of the spherical indenter in mm, A = Area of indenter impression in mm2 (Surface area of indentation), Di = diameter of the resulting indenter impression in mm d  0.20 - 0.70 where X is D loading factor related to material of part. Table shows loading factors depended on to the material. First of all, application load F, has to be selected. F=X.D2 and Table 1. The diameters of the spherical indenter, loading factors, and loads Loading Factors [X] 30 10 Ball Diameters D [mm] 10 5 2,5 1 Measurement Range Material Groups F=X.D2 F=X.D2 F=X.D2 F=X.D2 =3000 kgf =750 kgf =187,5 kgf =30 kgf F=X.D2 F=X.D2 F=X.D2 F=X.D2 5 =1000 kgf =250 kgf =62,5 kgf =10 kgf F=X.D2 F=X.D2 F=X.D2 F=X.D2 2,5 =500 kgf =125 kgf =31,25 kgf =5 kgf 67-450 HB 22-315 HB 11-158 HB Steel, cast iron., Ti Alloys. Cu and light metal alloys, brass, Bronze Pure Al, Mg, cast brass Zn, F=X.D2 F=X.D2 F=X.D2 F=X.D2 1,25 =250 kgf =62,5 kgf =16,6 kgf =2,5 kgf F=X.D2 F=X.D2 F=X.D2 F=X.D2 0,5 =125 kgf =31,5 kgf =7,8 kgf =1,25 kgf 6-78 HB 3-39 HB Bearing alloys Pb, Sn, soft metal F=X.D2 F=X.D2 F=X.D2 F=X.D2 =50 kgf =12,5 kgf =3,25 kgf =0,5 kgf For choosing ball diameter with respect to material depth Table 2 has to be used. Table 2.Ball diameters with respect to material depth  Depth [mm] Ball Diameter D [mm] >6 2.5 –5 –10 3–6 2.5 –5 2–3 2.5 Finding the application load. Table 1 and Table 2 have to be used. For example for cast iron material using Table 1, X=30 and using Table 2, D=2,5 mm. So; F=X.D2=30.2,52=187,5 kgf 39 MANUFACTURING LABORATORY  Perform tests and use the formula, H B  F 2F  A π.D D  D 2  d 2    d  0.20 - 0.70 must be satisfied. D  The diameter of the impression is the average of two readings at right angles and the use of a Brinell hardness number table can simplify the determination of the Brinell hardness. A well structured Brinell hardness number reveals the test conditions, and looks like this, "75 HBS 10/500/30" which means that a Brinell Hardness of 75 was obtained using a 10mm diameter hardened steel ball with a 500 kgf load applied for a period of 30 seconds. Relation between HB and tensile strength σmax=C.HB , where C is a factor changing with respect to material type like; Csteel=0,35, Cheat treated =0,36, CCu Alloys=0,55  After test, verify that EXPERIMENTAL STUDIES: For brass specimen ; For steel specimen; d  22 div d  22 * 0,05  1,1 mm d d must be 0,20   0,70 D D d 1,1   0,44 so we can apply Brinell test D 2,5 2.P HB   .D D  (D 2  d 2 )  HB  d  15 div d  15 * 0,05  0,75 mm d d must be 0,20   0,70 D D d 0,75   0,3 so we can apply Brinell test D 2,5 2.P HB   .D D  (D 2  d 2 )   2 .150  . 2,5 2,5  (2,5 2  1,12 )   HB    2 .150  . 2,5 2,5  (2,5 2  0,75 2 )  H B  149,79 H B  331,71 We can write the obtained value as 149,79 HB/2,5/150/15 We can write the obtained value as 331,71 HB/2,5/150/15 Material Diameter Impression (mm) Brass Steel of Diameter of the ball indenter (mm) Applied (kgf) load Brinell Hardness Number (kgf/mm2) 1,1 2,5 150 149,79 0,75 2,5 150 331,71 d1 = Your Measurement-I H BAverage  d2 = H B1  H B2  H B3 3 d3 = d1 = Your Measurement-II H BAverage  d2 = d3 = 40 H B1  H B2  H B3 3 MANUFACTURING LABORATORY Questions and Discussions: 1. 2. 3. 4. 5. Calculate the Rockwell and Brinell hardness values of your test materials. Explain the differences of Brinell and Rockwell methods. How to calculate tensile stress using Brinell hardness values? Explain the Brinell and Rockwell hardness numbers. What are the Rockwell’s advantages in comparison to Brinell hardness test? 41 THERMODYNAMICS LABORATORY HEAT PUMP EXPERIMENT 1. OBJECTIVE: Objective of the experiment is to determine the heating/cooling capacity and the efficiency of heating/cooling of a heat pump. 2. THEORY: Heat pump is a device that transfers heat from a low-temperature medium to a high temperature one consuming mechanical energy. The main components of a heat pump are illustrated in Figure (1). All heat pumps consist of four main components as seen below; -Compressor -Evaporator -Condenser -Expansion valve Figure 1 The refrigerant enters the compressor as a vapour and is compressed to the condenser pressure. It leaves the compressor at a relatively high temperature, and then enters condenser as superheated vapour. In the condenser, the superheated vapour first becomes saturated vapour and then condenses by rejecting heat to the surrounding medium (Hot region). The refrigerant leaves the condenser as saturated-liquid and enters the expansion valve in which its pressure is reduced (at constant enthalpy). The refrigerant then enters the evaporator and it completely evaporates by absorbing heat from the surrounding medium (Source). The cycle is completed as the refrigerant leaves the evaporator and returns the compressor. With the above process, heat is absorbed from a low-temperature source in the evaporator and is rejected to a high-temperature one in the condenser. The T-s and logP-h diagrams of a practical vapour compression cycle are illustrated in Figures (2a) and (2b) respectively. 42 THERMODYNAMICS LABORATORY Figure 2 2.1. AMOUNT OF THE REFRIGERANT WITHIN THE SYSTEM The mass flow rate of refrigerant cycled within the system can be read on refrigerant flow meter as g/s directly. The other method to determine the amount of refrigerant cycled within the system is explained as follow; To achieve the heating/cooling capacity required, certain amount of refrigerant must be cycled within the system. This can be calculated using technical data of experimental rig and physical properties of refrigerant. m=Vn (1) in which  = Volumetric efficiency of compressor (70) V = Stroke volume of compressor (15 cm3) n = Rotation of compressor (2800 rev/min)  = Density of refrigerant at inlet of compressor 2.2. CALCULATION OF HEATING/COOLING CAPACITY AND COMPRESSOR POWER There are two kinds of calculation procedure to find of heating/cooling capacity and compressor power of the system as theoretical and experimental methods. 2.2.1. Theoretical Calculation Heat transferred from the condenser to the hot region is defined as heating capacity of the system and this is calculated from the equation; 43 THERMODYNAMICS LABORATORY Q h  mr ( h 2  h 3 ) (2) In which h2 and h3 respectively shows the enthalpy of the superheated refrigerant at the exit of the compressor and the liquid refrigerant at the exit of the condenser. mr represents the mass flow rate of the refrigerant within the system as kg/s. Cooling capacity is the heat absorbed from the low-temperature source to the evaporator and this is obtained from the equation; Qc  mr (h1  h 4 ) (3) In which h4 and h1 is the enthalpy of the refrigerant at the inlet and exit of the evaporator respectively. Power of the compressor is given by; Wcom  mr (h1  h2 ) (4) Thus, the theoretical heating and cooling efficiencies are calculated using equations below. The heating efficiency (Coefficient of performance): COPh  Qh Wcom (5) Qc Wcom (6) and the cooling efficiency is; COPc  2.2.2. Experimental Calculation When the flow rate and the temperature of the water at the inlet/exit of the evaporator and the condenser are known, heating/cooling capacity can be calculated experimentally. The heating capacity can be evaluated from; Qh=mc.Cp.(T9-T7) (7) In which Cp is the specific heat of water. T9 and T7 are temperature of outlet and inlet of condenser, respectively. mc is mass flow rate of water flow around condenser. Similar to heating capacity, the cooling capacity can be calculated from the equation; Qc=me.Cp.(T5-T6) (8) T6 and T5 are temperature of outlet and inlet of evaporator, respectively. me is mass flow rate of water flow around evaporator. Power of the compressor is found from the equation below: 44 THERMODYNAMICS LABORATORY Wcom  21600 x (9) In which x is the time for 1 revolution of meter at second and 21600 is the meter constant of the Watt-hour meter and it can be explained as follows; The watt-hour meter has a disc, which rotates as energy is consumed and the number of revolutions made for the consumption of 1 kWh is stated on the face of the meter. For 220/240 units the rate is usually 166.66 rev. per kWh (3.6 106 J). This rate gives meter constant of 3.6 106 / 166.66 = 21600 J/rev Thus, the experimental calculation for heating and cooling efficiency is made using eq.(5) and eq.(6) respectively. 3. EXPERIMENTAL RIG Detailed schematic of the heat pump is given in Figure (3) and its main components are explained on this figure. The numbers represented on figure (3) are defined as follows; 1- R12 at Compressor Inlet 2- R12 at Compressor Delivery 3- R12 at Condenser Outlet 4- R12 at Expansion Valve Outlet 5- Water at Evaporator Inlet 6- Water at Evaporator Outlet 7- Water at Compressor Inlet 8- Water at Condenser Inlet 9- Water at Condenser Outlet 10-Air at Evaporator Outlet 4. EXPERIMENTAL PROCEDURE Select water as the heat source (Turn the diverter valve to the water position.) and ensure that it is flowing at the maximum flow rate. Adjust the condenser water to a high flow rate and switch on. When stability is reached, note the condenser pressure (P2) and the evaporation temperature (T4), and then make the observations set out on table. Reduce the condenser water flow rate so that the condenser pressure (P2) increases by approximately 100 kN/m2 . Adjust the source water flow rate until t4 returns to its initial value. When stability is reached repeat the observations. Repeat in increments of approximately 100 kN/m2 in the value of P2 until the pressure reaches about 1400 kN/m2 (gauge). 5. PREPARING REPORT A) Present the experimental data and the values calculated in a table such as below. B) Draw a cycle on logP-h chart to the each test, and then using these enthalpies, the experimental data and the equations given above, calculate the heating/cooling efficiency theoretically and experimentally. C) Plot the variation of heat delivered in condenser versus condensing temperature (Tcon- Qh graph). Interpret the graph. D) Plot the variation of heating/cooling efficiency versus condensing temperature ( Tcon- COPc and Tcon- COPh Diagram). Interpret the graphs. E) Plot the variation of electrical input versus condensing temperature (Tcon- Wcom graph). Interpret the graph. F) Plot the variation of heating/cooling efficiencies versus compressor power(W conCOPc and Wcon-COPh ). 6. DISCUSSION 45 THERMODYNAMICS LABORATORY A) Discuss the differences between the experimental and the theoretical values calculated. B) Discuss the experimental errors. C) Discuss the reasons of the fact that a cooling system can also be used for heating. D) What are the selection criteria for a refrigerant? E) Design a heat pump system that will be used for heating and cooling a building. Draw schematically and discuss. 46 THERMODYNAMICS LABORATORY Table 1. The results of experiment Test 1 Electrical counter: Time X s Mass flow rate of refrigerant mr g/s Pressure of evaporator P1 kN/m2 Pressure of Condenser P2 kN/m2 Tcon C Comp. Suction temperature T1 C Comp. outlet temperature T2 C Condenser outlet temperature T3 C Evaporator inlet temperature T4 C Water mass flow rate of evaporator side me g/s Water temperature of inlet of evaporator T5 C Water temperature of outlet of evaporator T6 C Water mass flow rate of condenser side mc g/s Water temperature of inlet of condenser T7 C Water temperature of outlet of comp. T8 C Water temperature of outlet of condenser T9 C Heating Capacity Qh W Heating efficiency COPI - Qc W Cooling efficiency COPS - Power of Compressor Wcom W Heating Capacity Qh W Heating efficiency COPI - Qc W Cooling efficiency COPS - Power of Compressor Wcom W Condensing Temperature ( Find from P 2 ) Theoretical Calculations Experimental Calculations Cooling capacity Cooling capacity 47 2 3 4 5 6 THERMODYNAMICS LABORATORY AIR CONDITIONING EXPERİMENT 1-) OBJECTIVE: Air Conditioning, which may be described as the control of the atmosphere so that a desired temperature, humidity, distribution and movement is achieved, is a rapidly expanding activity throughout the world. The aim of the experiment is to demonstrate simple air conditioning processes, which are heating, cooling and humidification. 48 THERMODYNAMICS LABORATORY 2-) INTRODUCTION: Applications for air conditioning are frequently encountered in homes, hospitals, public meeting places, mines, shops, offices, factories, land, air and sea transport, but there are numerous other applications in which human comfort is not the prime consideration. These include textile and printing industries, computers, laboratories, photographic and pharmaceutical industries, manufacture, inspection and storage of sensitive equipment, horticulture, animal husbandry, food storage and many others. Air conditioning plants usually consist of a number of components (e.g. fans, filters, heat exchangers, humidifiers, etc.) enclosed in a sheet metal casing. Intake to the plant is usually from a clean external atmosphere (plus, in some cases, air recirculated from the building) and delivery from the plant is via ducting to suitable distribution points. 2.a-)Components: Filters Coarse - usually wire mesh. To remove insects, leaves and other large airborne particles. Fine - usually paper or viscous type. To remove most of the airborne dust.  Fans are required to cause the air movement and to make good the pressure drop due to the duct and system resistances. Heat Exchangers which usually are finned on the air side, are needed to increase or decrease the air temperature. Heaters may use steam, hot water or electricity as the heating medium. Coolers may be supplied with chilled water or may be of the direct expansion type in which liquid refrigerant boils at a low temperature. 49 THERMODYNAMICS LABORATORY Humidifiers are used to increase the moisture content of the air. Water may be sprayed directly into the air, may be evaporated from a moist surface, or alternatively, steam may be injected into the air. Dehumidifiers are used to reduce the moisture content of the air. This is usually achieved by cooling the air below its dew point so that surplus moisture is precipitated. Sometimes hygroscopic materials are used to achieve dehumidification, but, of course, these require regeneration. Eliminators are specially shaped baffles through which the air flows and which remove entrained water droplets from the air stream. Mixers are employed to blend two streams of air to achieve a desired condition and/or economy. Instruments and Controls are needed to sense the condition of the air at various stations, and to vary the output of the components to bring about the desired final condition. Boiler for humidification and/or for the air heaters. Refrigeration Plant for the air coolers/dehumidifiers. Hygrometers are instruments for measuring the moisture content of the atmosphere. There are many types of hygrometer. The Air Conditioning Laboratory Unit employs the well known wet and dry bulb type hygrometer for determining air condition. 2.b-)Comfort Conditions: A man rejects up to about 400W (according to his level of activity) to the atmosphere. This heat loss is accounted for by a combination of convection and radiation from his body surfaces, and evaporation of moisture from his lungs and skin. As the air temperature increases, the amount of heat which can be rejected by convection and radiation decreases, thus the evaporation component must increase. If the relative humidity of the atmosphere is already high, evaporation will be sluggish, skin surfaces become wet, and the person feels uncomfortable. In hot and humid conditions, personnel are quickly exhausted and are unable to maintain vigorous activity. In addition, these conditions favour the growth of moulds and fungus -some of which cause skin ailments. Very low humidities on the other hand, cause rapid evaporation from the lungs, throat, eyes, skin and nasal passages and these can also cause discomfort. 50 THERMODYNAMICS LABORATORY 2.c-)Human Comfort: Depending upon their physical activity, clothing and surroundings, most people are comfortable in gently moving air (free of draughts) which is at about 20 C and which has a relative humidity of about 50%. However, there is considerable variation of what is considered comfortable between individuals and between nations, and in any case, there is a zone of temperature and humidity around the “ideal” which is acceptable to most people. The prime function of many air conditioning plants is to provide a comfortable environment in terms of air freshness, temperature, humidity and movement. 3-)EXPERİMENTAL RIG: Experimental set-up can be seen in Figure 1. Specifications and instrumentation are given below. 3.a-)Specification: Air Throughput 0.13 m3/s (max.) Pre-heater Extended fin electric heating elements. 2 x 1.0 kW (nominally) at 220 V.  Cooler Direct expansion, extended fin coil. Cooling rate approx. 2.0 kW. Re-heater Extended fin electric heating elements. 2 x 0.5 kW (nominally) at 220V. Fan Centrifugal (variable speed). Power input approx. 120W, at 240V 50Hz. Boiler Electrically heated and working at atmospheric pressure. Fitted with water level gauge and float level controller. Heaters: 1 x 1.0 kW and 2 x 2.0kW at 220V (nominally). Refrigerator Hermetic unit with air cooled condenser. Refrigerant: R134a Tetrafluoroethane CF3CH2F Compressor speed: 2700 to 3000 rev/min. at 50Hz. according to load. 3300 to 3600 rev/min. at 60Hz. 3 Swept volume: 25.95 cm /rev. 51 THERMODYNAMICS LABORATORY 3.b-)Instrumentation: Air Flow Measurement Orifice plate with inclined tube manometer. Temperature Measurement 4 pairs Wet and Dry Bulb glass thermometers 300 mm long, selected to agree within 0.2C of each other at normal operating conditions.  Refrigerant Circuit 3 x 300mm Glass thermometers. 3.c-)Useful data: * The fan power input is approximately 72 W at normal operating conditions. * The specific heat of air Cpair=1.005 kJ/(kg.K) * The specific heat of water Cpwater=4.18 kJ/(kg.K) * Heat loss from Boiler: 4.3 W/K. * Orifice calibration: ma  0.0504 z kg/s. D where, z= Orifice differential (mmH2O) vD= Specific volume of air at Station D (from psychrometric chart) * Compressor swept volume: 25.95cm3/rev. * 1 bar = 105 N/m2 = (or 100 kPa) =14.5 lbf/in2 = * Absolute pressure = Gauge pressure + Atmospheric pressure * Standard atmospheric pressure = 101.3 kN/m2 (1013 mbar). * 1kW = 3412 Btu/h. 4-)EXPERIMENTAL PROCEDURE: Turn on the main power switch of the unit and adjust a fan speed around medium level. Start the refrigeration circuit turning on its switch. Increase the power inputs of Pre-heater, Re-heater and Boiler from minimum to maximum for the each test. Collect the data which are seen on the observation sheet while the system is running. 52 THERMODYNAMICS LABORATORY 4.a-)Specimen Calculations: Obtain the following air properties from the Psychrometric chart. Test Station 1 Enthalpy hA= hB= hC= hD= Moisture wA= wB= wC= wD= Enthalpy hA= hB= hC= hD= Moisture wA= wB= wC= wD= Enthalpy hA= hB= hC= hD= Moisture wA= wB= wC= wD= Enthalpy hA= hB= hC= hD= Moisture wA= wB= wC= wD= 2 3 4 From tables: A B C D hg at atmospheric pressure = 2676 kJ/kg hw at 20 C (assumed) = 84 kJ/kg he at 20 C (assumed) = 84 kJ/kg 4.b-)Calculation of air mass flow rate: Air mass flow rate, ma  0.0504 z D (1) 4.c-)Application of energy and mass balances between A and B: 53 THERMODYNAMICS LABORATORY For the system enclosed by the chain line: By conservation of mass, mw  ma  wB  wA  kg/s Heat transfer rate – Work transfer rate = Enthalpy transfer rate (2)  Q   (P ) Heat transfer rate – Work transfer rate:  Q B P f (3)  a hB  hA   m  whw Enthalpy transfer rate:  m (4) Heat loss from the Boiler to the ambient:  4.3W / K TBoiledWater  TAmbient  (5) TBoiledWater  100 C 4.d-)Boiler theoretical evaporation rate: Assumptions, (i) Steam produced is saturated at atmospheric pressure and has a specific enthalpy of 2676 kJ/kg. (ii) The feed water is at 20 C and has a specific enthalpy of 84 kJ/kg. Rate of evaporation  No min al Heater Input - Calculated loss  Steam Spec. Enth. - Feed Water Spec. Enth. (6) This may be compared with the value obtained from the change of specific humidity between A and B. 4.e-)Refrigerant properties: Obtain the following R134a properties from the R134a log p-h diagram. (Note: The throttling or expansion process 3 - 4 is assumed to be adiabatic, h3 = h4) Test 1 kJ/kg Test 2 Test 3 Test 4 h3 = h4= h3 = h4= h3 = h4= h3 = h4= -- x4= x4= x4= x4= kJ/kg h1= h1= h1= h1= m3/kg v1= v1= v1= v1= 54 THERMODYNAMICS LABORATORY 4.f-)Application of energy and mass balances between B and C: For the system enclosed by the chain line,  a  wB  wC  Calculated rate of condensation from air stream:  m This value should be close to the observed rate of condensed water. Heat transfer rate = Enthalpy change rate - Work transfer rate There is no work transfer rate between B and C, thus     Q B C  ma hC  hB   mehe  mr h1  h4  (7) 4.g-)Application of energy and mass balances between C and D 55 THERMODYNAMICS LABORATORY Since there has been no increase or decrease in the moisture content between C and D, wC and wD should be equal.    1 kW , Q  m  m  a hD  hC  and Q  aCPair TDdry  TCdry Q r a aT  (8) 4.h-)Volumetric efficiency of compressor:  m  r 1 Volume flow rate at compressor intake, V 1 Compressor swept volume,  25.95 10-6 x (9) (10) 2900 3 m /s 60 Volumetric efficiency of compressor (%), vol   V 1 Swept volume (11) 5-)PREPAIRING REPORT: A) Fill out the table calculating the results of equations for each test. Equation No 1 Test 1 Test 2 Test 3 Test4 2 3 4 5 6 7 8 9 10 11 B) Draw an industrial air conditioning unit and explain parts of it. C) What is humidification and de-humidification. Explain why air is humidified or dehumidified? D) Give examples about air conditioning units which have no humidification control. 56 THERMODYNAMICS LABORATORY E) Draw a simple sketch which shows the connections of air conditioned room, air conditioning unit, chiller, boiler, and cooling tower together. Explain what to do for cooling in summer or for heating in winter? 6-)DISCUSSION: A) Eq.(4) should be equal Eq.(3)+Eq.(5). Discuss why it is? If there is any difference between them, calculate the degree of inaccuracy explaining where it comes from. B) If Eq.(7) is not equal to zero, what does it mean? Give explanation for the positive and negative values. C) In Eq.(8), compare the results of three different equations. What do you say about these three equations? Calculate the differences between them. 57 AUTOMOTIVE LABORATORY 2 1. TYPES of FUEL Fuels for transportation and power generation can come in all phases: solid, liquid, or gas. Naturally occurring solid fuels include wood and other forms of biomass, peat, lignite, and coal. Liquid fuels are derived primarily from crude oil. The refining processes of fractional distillation, cracking, reforming, and impurity removal are used to produce many products including gasoline, diesel fuels, jet fuels, and fuel oils. Figure 1.1 shows typical end products from crude oil, with the lighter, more volatile components at the top. The most widely used gaseous fuels for power generation and home heating are natural gas and liquid petroleum gas. In nature, natural gas is found compressed in porous rock and shale formations sealed in rock strata below ground. Natural gas frequently exists near or above oil deposits. Raw natural gas from northern America contains methane (~87.0–96.0% by volume) and lesser amounts of ethane, propane, butane, and pentane. Liquefied petroleum gas (LPG) consists of ethane, propane, and butane produced at natural gas processing plants. LPG also includes liquefied refinery gases such as ethylene, propylene, and butylene. Gaseous fuels can also be produced from coal and wood but are more expensive. Gasoline is used primarily in lightweight vehicles. As seen in Fig. 1.1, gasoline is a mixture of lightdistillate hydrocarbons from refined crude oil. The precise composition of gasoline varies seasonally and geographically and depends on the producer of the fuel. Diesel fuel is used in medium and heavy vehicles, as well as in rail and marine engines. Typical diesel fuel is also a mixture of hydrocarbons from refined crude oil, but it is composed of a blend of fuels with a higher boiling point range than that of gasoline. Fuel oil (commonly called “bunker” fuel) is widely used in large marine vessels (1). 58 AUTOMOTIVE LABORATORY 2 1.1. Diesel Fuel The word "diesel" is derived from the German inventor Rudolf Diesel who in 1892 invented the diesel engine. Diesel engines are a type of internal combustion engine. Rudolf Diesel originally designed the diesel engine to use coal dust as a fuel. He also experimented with various oils, including some vegetable oils, such as peanut oil, which was used to power the engines which he exhibited at the 1900 Paris Exposition and the 1911 World's Fair in Paris. Diesel fuel in general is any liquid fuel used in diesel engines. The most common is a specific fractional distillate of petroleum fuel oil, but alternatives that are not derived from petroleum, such as biodiesel, biomass to liquid (BTL) or gas to liquid (GTL) diesel, are increasingly being developed and adopted. To distinguish these types, petroleum-derived diesel is increasingly called petrodiesel. Ultra-low sulfur diesel (ULSD) is a standard for defining diesel fuel with substantially lowered sulfur contents. Petroleum diesel, also called petrodiesel, or fossil diesel is produced from the fractional distillation of crude oil between 200 °C and 350 °C at atmospheric pressure, resulting in a mixture of carbon chains that typically contain between 8 and 21 carbon atoms per molecule. Diesel-powered cars generally have a better fuel economy than equivalent gasoline engines and produce less greenhouse gas emission. Their greater economy is due to the higher energy per-litre content of diesel fuel and the intrinsic efficiency of the diesel engine. While petrodiesel's higher density results in higher greenhouse gas emissions per litre compared to gasoline, the 20–40% better fuel economy achieved by modern diesel-engined automobiles offsets the higher per-litre emissions of greenhouse gases, and a dieselpowered vehicle emits 10-20 percent less greenhouse gas than comparable gasoline vehicles. Petroleum-derived diesel is composed of about 75% saturated hydrocarbons and 25% aromatic hydrocarbons. The average chemical formula for common diesel fuel is C12H23, ranging approximately from C10H20 to C15H28 (2). 1.2. Gasoline Gasoline or petrol is a petroleum-derived liquid mixture which is primarily used as a fuel in internal combustion engines. It is also used as a solvent, mainly known for its ability 59 AUTOMOTIVE LABORATORY 2 to dilute paints. It consists mostly of aliphatic hydrocarbons obtained by the fractional distillation of petroleum, enhanced with iso-octane or the aromatic hydrocarbons toluene and benzene to increase its octane rating. Small quantities of various additives are common, for purposes such as tuning engine performance or reducing harmful exhaust emissions. Some mixtures also contain significant quantities of ethanol as a partial alternative fuel. Gasoline is produced in oil refineries. Material that is separated from crude oil via distillation, called virgin or straight-run gasoline, does not meet the required specifications for modern engines (in particular octane rating; see below), but will form part of the blend. The bulk of a typical gasoline consists of hydrocarbons with between 4 and 12 carbon atoms per molecule (commonly referred to as C4-C12). Many of the hydrocarbons are considered hazardous substances and are regulated in the United States by the Occupational Safety and Health Administration. Thematerial safety data sheet for unleaded gasoline shows at least fifteen hazardous chemicals occurring in various amounts, including benzene (up to 5% by volume),toluene (up to 35% by volume), naphthalene (up to 1% by volume), trimethylbenzene (up to 7% by volume), Methyl tert-butyl ether(MTBE) (up to 18% by volume, in some states) and about ten others (2). Discussed in this section will be some key fuel properties as well as the methods to measure these properties. The properties listed below will be specific gravity, kinematic viscosity, cetane number, octane number, flash point, heat value (calorimeter), cold behaviors (pour point, cloud point, cold filter plugging point), and reid vapor pressure. 60 AUTOMOTIVE LABORATORY 2 FUEL PROPERTIES TEST 1 1. Density (Specific Gravity) Density (or specific gravity) is an indication of the density or weight per unit volume of the fuel. Density is an essential parameter. As the density increases, the energy content increases per unit volume. Given an unchanging injected quantity of fuel, the energy supplied to the engine increases with the density, which increases engine performance. However, the exhaust emissions and, especially, the particles increase under a full load due to the richer mixture. On the other hand, the volumetric fuel consumption increases as density decreases. Two methods most commonly used to measure density are:  Standard Test Method for Density, Relative Density (Specific Gravity) or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method : The sample is brought to the prescribed temperature and transferred to a cylinder at approximately the same temperature. The appropriate hydrometer is lowered into the sample and allowed to settle. After temperature equilibrium has been reached, the hydrometer scale is read, and the temperature of the sample is noted. If necessary, the cylinder and its contents may be placed in a constant temperature bath avoid excessive temperature variation during the test.  Standard Test Method for Density, Relative Density of Liquids by Digital Density Meter: A small volume (approximately 0.7 mL) of liquid sample is introduced into an oscillating sample tube and the change in the mass of the tube is used in conjunction with calibration data to determine the density of the sample (3). The densities of the fuels measure with Kyoto Electronics DA-130 type density meter. This density meter uses the resonant frequency method to measure the densities. With the density meter we can also measure the specific weight, API gravity, % Brix, volume and mass alcohol rates. The measurement interval of the device is 0 to 2 g/cm 3 and 0 to 40 ºC. The device has a sensitivity of ±0.001 g/cm3, and a stability of 0.0001 g/cm3. The device is measuring according to the standards of TS EN ISO 12185 (4). 61 AUTOMOTIVE LABORATORY 2 2. Viscosity To define kinematic viscosity it is useful to begin with the definition of viscosity. Simply stated, viscosity, which is also called dynamic viscosity (η), is the ease with which a fluid will flow. Technically it is the ratio of the shear stress to the shear rate for a fluid. In contrast, the kinematic viscosity (ν) is the resistance to flow of a fluid under gravity (5). Fuel viscosity is specified in the standard for diesel fuel within a fairly narrow range. Hydrocarbon fuels in the diesel boiling range easily meet this viscosity requirement. Most diesel fuel injection systems compress the fuel for injection using a simple piston and cylinder pump called the plunger and barrel. In order to develop the high pressures needed in modern injection systems, the clearances between the plunger and barrel are approximately one ten-thousandth of an inch. In spite of this small clearance, a substantial fraction of the fuel leaks past the plunger during compression. If fuel viscosity is low, the leakage will be enough to cause a significant power loss for the engine. If fuel viscosity is high, the injection pump will be unable to supply sufficient fuel to fill the pumping chamber. Again, the effect will be a loss in power. Two methods most commonly used to measure viscosity are:  Standard Test Method for Kinematic Viscosity : The time is measured for a fixed volume of liquid to flow under gravity through the capillary of a calibrated viscometer under a reproducible driving a head and at a closely controlled and known temperature. The kinematic viscosity is the product of the measured flow time and the calibration constant of the viscosimeter.  The viscosities of the fuels measure with Saybolt Universal Viscosimeter produced from Ubbelohde tube with ASTM D 88 standards. The measurement results record in seconds. Then using a conversion table the results convert from SSU (Saybolt Universal Second) to centistokes (cst) unit. The measurements are done at 40 °C according to the TS 1451 EN ISO 3104 (3). I. Tanaka AKV 202 type kinematic viscosity meter is used for The kinematic viscosity measurements during the tests which has a measurement range of 20100 oC. 62 AUTOMOTIVE LABORATORY 2 3. Cetane Number The first diesel engines were large and slow-speed and were not particularly sensitive to the quality of the fuel they burned. As steady improvements were made to the engine, there was a need to improve fuel quality as well. Gradually, the heavier, more viscous, diesel fuels disappeared with lighter and higher speed engines. The higher speed engines are more sensitive to the ignition quality of the fuel; therefore, cetane numbers became the property of greatest concern to both producers and users. Cetane number is a measure of the fuel’s ignition and combustion quality characteristics. The Cetane number measures how easily ignition occurs and the smoothness of combustion. Higher the cetane number results better its ignition properties. Cetane number affects a number of engine performance parameters like combustion, stability, drivability, white smoke, noise and emissions of carbon monoxide (CO) and hydrocarbons (HC). The cetane number is the primary specification measurement used to match fuels and engines. It is commonly used by refiners, marketers and engine manufacturers to describe diesel fuels. Higher cetane number fuels tend to reduce combustion noise, increase engine efficiency, increase power output, start easier (especially at low temperatures), reduce exhaust smoke, and reduce exhaust odor (3). The cetane numbers measure by Zeltex ZX440 type device, which works under the close infrared spectrometer (NIR) principal. With the help of this principal the cetane number measurement experiment became very fast and cheap with only 3% error compared to the time consuming expensive motor tests. 4. Octane number The critical fuel property of gasoline for internal combustion engines is resistance to engine knocks, expressed as the octane number of the gasoline. During a normal (no knock) combustion cycle, a flame front travels smoothly from the point of ignition at the spark plug outward toward the cylinder walls. While this is occurring, the end gas, or unburned fuel/air mixture ahead of the flame front is heated and compressed. If the end gases ignite before 63 AUTOMOTIVE LABORATORY 2 the flame front arrives, the resulting sudden pressure wave reverberates across the combustion chamber, causing an audible engine knock. This adversely affects output power and dramatically increases heat transfer to the piston and other combustion chamber surfaces. While this can cause damage on its own if severe enough, knock induced preignition can cause rapid catastrophic engine failure. This tends to be a runaway condition. Once started, it gets progressively worse until eventual engine failure, unless the throttle/load is cut quickly, as failure can occur in less than a few minutes. Research Octane Number (RON) The research method settings represent typical high load (throttle open) and low to medium engine speeds resulting in low inlet mixture temperatures and moderate loads on the engine. Motor Octane Number (MON) The conditions of the Motor method represent severe, sustained high engine speed, high load (but no wide open throttle) driving (2). Octane numbers measure by Zeltex ZX440 liquid fuel analyzer. It’s measurement principle is based on Near Infra-Red (NIR) technology. Light energy that enters the sample is scattered and absorbed with in the sample, and directly displays the product’s constituent concentrations. The picture octane number analyzer is given in figure 3. and some properties of equipment are outlined in table 1 (6). 64 AUTOMOTIVE LABORATORY 2 Table 1. Properties of Octane Analyzer(6) Optical Capabilities Spectrum Range 37 Filters covering wavelengths from 604 to 1045 nm Scan Speed Up to 10 scans per seconds Optical Range 0 to 5 AU Resolution 0.00001 AU Stability 0.02 mili-AU Measurement Modes Diffuse transmittance Measurement Time Up to 30 seconds Measurement Data Log 1/T values, 1 to 37 primary wavelengths, 442 usable wavelengths Sample Information Sample Size 200 ml with 75 mm wavelength Sample Holder Reusable glass with chemical seal cover Measurement Range From 0.05 to 99%. 5. Copper Strip Corrosion The test method for copper strip corrosion is:  Standard Test Method for Detection of Copper Corrosion from Petroleum Products by the Copper Strip Tarnish Test: A polished copper strip is immersed in a given quantity of sample and heated at a temperature and for a time characteristic of the material being tested. At the end of this period the copper strip is removed, washed, and compared with the ASTM Copper Strip Corrosion Standards. 65 AUTOMOTIVE LABORATORY 2 The copper strip corrosion test covers the detection of the corrosiveness to copper of aviation gasoline, aviation turbine fuel, automotive gasoline, natural gasoline, or other hydrocarbons having a Reid vapor pressure no greater than 124 kPa (3). Crude petroleum contains sulfur compounds, most of which are removed during refining. However, of the sulfur compounds remaining in the petroleum product, some can have a corroding action on varies metals and this corrosivity is not necessarily related directly to the total sulfur content. The copper strip corrosion test is designed to assess the relative degree of corrosivity of a petroleum product. The corrosiveness of a fuel is measure using the copper strip corrosion test, which is TS 2741 EN ISO 2160. Copper and copper compounds tend to be particularly susceptible to chemical attack. The corrosivity of a fuel has implications on storage and use of the fuel. As an indicator of the tendency of a fuel to cause corrosion, polished copper strips are placed in the fuel for 3 hours at 50 °C. Then the strips wash in a solvent and compare to the descriptions in TS standard (5). 66 AUTOMOTIVE LABORATORY 2 FUEL PROPERTIES TEST 2 1. Flash Point The flash point is the lowest temperature at which a combustible mixture can be formed above the liquid fuel. It is dependent on both the lean flammability limit of the fuel as well as the vapor pressure of the fuel constituents. The flash point is determined by heating a sample of the fuel in a stirred container and passing a flame over the surface of the liquid. If the temperature is at or above the flash point, the vapor will ignite and an easily detectable flash can be observed (5). The flashing point parameter is used to limit the level of un-reacted alcohol remaining in the finished fuel. The flashing point also has an important connection with the legal requirements and safety precautions involved in fuel handling and storage. A low flash point fuel can be a fire hazard, subject to flashing, with possible continued ignition and explosion. Low flash point can also indicate contamination with low-flash fuels such as gasoline. The flash point of a fuel has no significant relation to the performance of the fuel in the engine. Auto-ignition temperature is not influenced by variations in flash point(3). Flash points measure with TS EN ISO 2719. Tanaka Automated Pensky-Martens Closed Cup Flash Point Tester is used for the flash point measurements during the tests which has a measurement range of 20-370 oC(5). A brass test cup of specified dimensions, is heated and the specimen stirred at specified rates by other of two defined procedures. An ignition source is directed into the test cup at regular intervals with simultaneous interruption of the stirring until a flash is detected (3) . 2. Reid Vapor Pressure (RVP) Reid vapor pressure (RVP), determined by the ASTM test method D323, is widely used in the petroleum industry to measure the volatility of petroleum crude oil, gasoline and other petroleum products. It is a quick and simple method of determining the vapor pressure at 37.8 °C (100 °F) of crude oil and petroleum products having an initial boiling point above 0 °C (32 °F)(6). The matter of vapor pressure is important relating to the function and operation of gasoline powered, especially carbureted, vehicles. Insufficient 67 AUTOMOTIVE LABORATORY 2 volatility may result in difficult starting in cold weather, poor cold start and warm-up driveability, engine deposits and crank case oil dilution, and increased tailpipe emissions. Excessive front-end volatility can produce fuel economy, poor hot driveability in fuel injected engines, vapor lock and carburetor icing in order engines, and increased running loss and evaporative emissions. The higher boiling fractions of the gasoline have significant effects on the emission levels of undesirable hydrocarbons and aldehydes. A reduction of 40°C in the final boiling point will reduce the levels of benzene, butadiene, formaldehyde, and acetaldehyde by 25%, and will reduce HC emissions by 20% (3). Reid vapor pressure measures by Tanaka AVP 30D automatic RVP analyzer. 3. Calorimeter The heat content or heat of combustion of a fuel is the amount of heat produced when the fuel is burned completely. Gross and net heats of combustion are the two values measured for the heat of combustion. The gross heat of combustion is the quantity of energy released when a unit mass of fuel is burned in a constant volume enclosure, with the products being gaseous, other than water is condensed to the liquid state. The fuel can be either liquid or solid, and contain only the elements carbon, hydrogen, nitrogen and sulfur. The products of combustion, in oxygen, are gaseous carbon dioxide, nitrogen oxides, sulfur dioxide, and liquid water. The net heat of combustion is quantity of energy released when a unit mass of fuel is burned at constant pressure, with all of the products, including water, being gaseous. Heat of combustion is usually reported in units of megajoules per kilogram (Mj/kg). Heat of combustion can be estimated by calculation from selected properties or measured using bomb calorimeter.  Standard Test Method for Heat of Combustion of Liquid Hydrocarbon Fuels by Bomb Calorimeter: this test method covers the determination of the heat of combustion of liquid hydrocarbon fuels ranging in volatility from that of light distillates to that of residual fuels (3). 68 AUTOMOTIVE LABORATORY 2 The heat capacities of liquid fuels can be measured automatically with IKA-Werke C2000 calorimeter. The working temperatures are between +15 ºC to +35 ºC. The combustion is done with a cotton wire instead of a tungsten wire (5). 69 AUTOMOTIVE LABORATORY 2 FUEL PROPERTIES TEST 3 1. Cloud Point All diesel fuels contain dissolved paraffin wax. As the temperature of the fuel decreases, so does the solubility of the wax in the fuel. At some point wax crystals will begin to precipitate. If enough wax precipitates the crystals can block fuel flow through screens, filters, and other restricted passages in the fuel system. The temperature at which the wax precipitation occurs depends upon the origin, type, refining, and boiling range of the fuel. This temperature is known as the cloud point of the fuel. As the cloud point goes up, the suitability of the fuel for low-temperature operation decreases.  Standard Test Method for Cloud Point of Petroleum Products: the specimen is cooled at a specified rate and examined periodically. The temperature at which a cloud is first observed at the bottom of the test jar is recorded as the cloud point. MPC-102 series has been designed for automatic determination of Cloud Point (CP) with small specimen size and shorter test cycle time while securing better test precision than the conventional manual methods (3). 2. Pour Point Before a fuel can be burned in an engine it must first be pumped from the fuel tank. The lowest temperature at which a fuel can be pumped is known as the pour point of the fuel(3). PP measurement is made utilizing a new ASTM D6749 on Standard Test Method for Pour Point of Petroleum Products test method namely Air Pressure Method, which yields eventually no bias against the conventional test method, repeatability/reproducibility of 1/2◦C and 2-3 times faster determinations. The typical repeatability and reproducibility are 1◦C and 2◦C respectively, when PP is determined at 1◦C intervals. This high precision attributes to the patented Air Pressure method, in which the disturbance to the formation of wax crystal structure through the test process is kept at a minimal and consistent level. With this high precision, PP can be 70 AUTOMOTIVE LABORATORY 2 determined at 1◦C intervals for more precise process control, and therefore a considerable savings in the process can be realized. Just set up a sample, select a test mode and then press the START key. The sample cools at the steepest possible rate without affecting the formation/ growth of wax crystal, which has been to be a critical factor for PP/CP determination. The test cycle time is typically 1/3 to 1/2 of that of the conventional tilting methods. Since the required sample volume is a mere 4,5 ml and the sample cup is a test-tube type removable jar, the sample handling is extremely easy. Use of Peltier Cells for sample cooling/heating made this mini tester not only compact in design but energy efficient. Depending on the temperature range, air, tap water or small chiller with anti-freeze suffices the cooling requirement (7). 3. Cold Filter Plugging Point The Cold Filter Plugging Point (CFPP), was developed for use in Europe. 1. The fuel is cooled by immersion in a constant temperature bath, making the cooling rate non-linear but comparatively much more rapid. 2. The CFPP is the temperature of the sample hen 20 mL of the fuel first fails to pass through a wire mesh in less than 60 s (3). The Cold Filter Plugging Point can be measured automatically with Tanaka AFP-102 Auto Cold Filter Plugging Point Tester. References 1. Sara McAllister, Jyh-Yuan Chen, A. Carlos Fernandez-Pello, “Fundamentals of Combustion Processes”, Springer-2011. 2. www.wikipedia. 3. George E. Totten, Steven R. Westbrook, Rajesh J. Shah, “Fuels and Lubricants Handbook: Technology, Properties, Performance and Testing” ASTM International2003. 71 AUTOMOTIVE LABORATORY 2 4. Aslı Abdulvahitoğlu, Ayşen YILMAZ, Kadir AYDIN, 2008. Fuel quality investigation of diesel fuel, biodiesel and different hydrocarbon blends, University of Çukurova Faculty of Mechanical Engineering and Architecture, 30 th Annual Symposium, 606610. 5. Mustafa Özcanlı, Development of Biodiesel Production Processes and Additives for Improvement of Diesel Performance and Emissions. Department of Mechanical Engineering. 2009. Adana. 6. Ufuk Yeni, Effect of Oxygenate Additives into Gasoline for Improved Fuel Properties. Department of Mechanical Engineering. 2005. Adana. 7. Ayşen Yılmaz, “Investigation of New Oil Additives”, Department of Mechanical Engineering. 2010. Adana. 72 AUTOMOTIVE LABORATORY 2 For Diesel TS– EN 590+A1 Properties Analyze Results METHOD Unit Values Flash Point TS EN ISO 2719 C 55 (minimum) Density (15C) TS EN ISO 12185 kg/lt 0.820 -0.845 Cetane Number TS 10317 EN ISO 5165 Viscosity(40C) TS 1451 EN ISO 3104 cSt Pour Point TS 1233 ISO 3016 C Cold Filter Plugging Point TS EN 116 C 51 (minimum) 2.00 - 4.50 -15(Maximum) 5(Maximum) Heat Value ASTM D 240 Copper Strip Corrosion TS 2741 EN ISO 2160 cal/g 1 (A,B,C) 73 II. III. AUTOMOTIVE LABORATORY 2 For Gasoline TS EN 228 Properties Analyze Results METHOD Unit Values kg/lt 0.720 -0.775 Density (15C) TS EN ISO 12185 Motor Octane Number TS EN ISO 5163 85 (minimum) Research Octane Number TS EN ISO 5164 95 (minimum) Reid Vapor Pressure TS EN 13016-1 Copper Strip Corrosion 45-60 (Summer) kPa 60-90 (Winter) TS 2741 EN ISO 2160 1 (A,B,C) 74 IV. V. AUTOMOTIVE LABORATORY 5 NEXA TRAINING SYSTEM Hydrogen Fuel Cells – Basic Principles The basic operation of the hydrogen fuel cell is extremely simple. The first demonstration of a fuel cell was by lawyer and scientist William Grove in 1839, using an experiment along the lines of that shown in Figures 1.1a and 1.1b. In Figure 1.1a, water is being electrolyzed into hydrogen and oxygen by passing an electric current through it. In Figure 1.1b, the power supply has been replaced with an ammeter, and a small current is flowing. The electrolysis is being reversed – the hydrogen and oxygen are recombining, and an electric current is being produced. Another way of looking at the fuel cell is to say that the hydrogen fuel is being ‘burnt’ or combusted in the simple reaction 2H2 + O2 → 2H2O However, instead of heat energy being liberated, electrical energy is produced. The main reasons for the small current are: • the low ‘contact area’ between the gas, the electrode, and the electrolyte – basically just a small ring where the electrode emerges from the electrolyte. 75 AUTOMOTIVE LABORATORY 5 • the large distance between the electrodes – the electrolyte resists the flow of electric current. → To overcome these problems, the electrodes are usually made flat, with a thin layer of electrolyte. The structure of the electrode is porous so that both the electrolyte from one side and the gas from the other can penetrate it. This is to give the maximum possible contact between the electrode, the electrolyte, and the gas. What Limits the Current? At the anode, hydrogen reacts, releasing energy. However, just because energy is released, it does not mean that the reaction proceeds at an unlimited rate. The reaction has the 76 AUTOMOTIVE LABORATORY 5 ‘classical’ energy. Although energy is released, the ‘activation energy’ must be supplied to get over the ‘energy hill’. If the probability of a molecule having enough energy is low, then the reaction will only proceed slowly. Except at very high temperatures, this is indeed the case for fuel cell reactions. The three main ways of dealing with the slow reaction rates are • the use of catalysts, • raising the temperature, • increasing the electrode area. → We see that fuel gas and OH− ions from the electrolyte are needed, as well as the necessary activation energy. Furthermore, this ‘coming together’ of H2 fuel and OH− ions must take place on the surface of the electrode, as the electrons produced must be removed. → The electrode is made highly porous. This has the effect of greatly increasing the effective surface area. Connecting Cells in Series – the Bipolar Plate To connect several cells in series, anode/electrolyte/cathode assemblies need to be prepared. These are then ‘stacked’ together. → If the electrical contact is to be optimized, the contact points should be as large as possible, but this would mitigate the good gas flow over the electrodes. → If the contact points have to be small, at least they should be frequent. However, this makes the plate more complex, difficult, and expensive to manufacture, as well as fragile. → Ideally the bipolar plate should be as thin as possible, to minimize electrical resistance and to make the fuel cells stack small. However, this makes the channels for the gas flow narrow, which means it is more difficult to pump the gas round the cell. Gas Supply and Cooling → Because the electrodes must be porous (to allow the gas in), they would allow the gas to leak out of their edges. The result is that the edges of the electrodes must be sealed. → ‘External manifolding’ has the advantage of simplicity. However, it has two major disadvantages (Figure 1.4). The first is that it is difficult to cool the system. Fuel cells are far from 100% efficient, and considerable quantities of heat energy as well as electrical power are generated. 77 AUTOMOTIVE LABORATORY 5 Figure 1.4. External manifolding → A more common arrangement requires a more complex bipolar plate. The plates are made larger relative to the electrodes and have extra channels running through the stack that feed the fuel and oxygen to the electrodes. Carefully placed holes feed the reactants into the channels that run over the surface of the electrodes. This type of arrangement is called ‘internal manifolding’ (Figure 1.5). Figure 1.5. Internal manifolding → It should now be clear that the bipolar plate is usually quite a complex item in a fuel cell stack. In addition to being a fairly complex item to make, the question of its material is often difficult. Graphite, for example, is often used, but this is difficult to work with and is brittle. Stainless steel can also be used, but this will corrode in some types of fuel cells. Ceramic materials have been used in the very high temperature fuel cells. The bipolar plate nearly always makes a major contribution to the cost of a fuel cell. Anyone who has made fuel cells knows that leaks are a major problem. If the path of hydrogen through a stack using internal manifolding is imagined, the possibilities for the gas to escape are many. The gas must reach the edge of every porous electrode – so the entire edge of every electrode is a possible escape route, both under and over the edge gasket. Other likely trouble spots are the joints between each and every bipolar plate. In addition, if there is the smallest hole in any of the electrolytes, a serious leak is certain. 78 AUTOMOTIVE LABORATORY 5 Fuel Cell Types Leaving aside practical issues such as manufacturing and materials costs, the two fundamental technical problems with fuel cells are • the slow reaction rate, leading to low currents and power, and • that hydrogen is not a readily available fuel. → The proton exchange membrane fuel cell (PEMFC) capitalizes on the essential simplicity of the fuel cell. The electrolyte is a solid polymer in which protons are mobile. The chemistry is the same as the acid electrolyte fuel cell of Figure 1.3. With a solid and immobile electrolyte, this type of cell is inherently very simple. These cells run at quite low temperatures, so the problem of slow reaction rates is addressed by using sophisticated catalysts and electrodes. Platinum is the catalyst, but developments in recent years mean that only minute amounts are used, and the cost of the platinum is a small part of the total price of a PEM fuel cell. The problem of hydrogen supply is not really addressed – quite pure hydrogen must be used, though various ways of supplying this are possible (Figure 1.6). Figure 1.6. PEM Fuel Cell schematic → Direct methanol fuel cells (DMFC) use the methanol as the fuel, as it is in liquid form, as opposed to extracting the hydrogen from the methanol. 79 AUTOMOTIVE LABORATORY 5  These cells have very low powers, but nevertheless, even at low power, there are many potential applications in the rapidly growing area of portable electronics equipment. Such cells, in the foreseeable future at least, are going to be of very low power, and used in applications requiring slow and steady consumption of electricity over long periods.  Their main problem is that the air and fuel supplies must be free from CO2, or else pure oxygen and hydrogen must be used. → The phosphoric acid fuel cell (PAFC) was the first to be produced in commercial quantities and enjoys widespread terrestrial use.  The problem of fuelling with hydrogen is solved by ‘reforming’ natural gas (predominantly methane) to hydrogen and carbon dioxide, but the equipment needed to do this adds considerably to the cost, complexity, and size of the fuel cell system.  Nevertheless, PAFC systems use the inherent simplicity of a fuel cell to provide an extraordinarily reliable and maintenance-free power system. Several PAFC systems have run continuously for periods of one year or more with little maintenance requiring shutdown or human intervention. → The solid oxide fuel cell (SOFC) operates in the region of 600 to 1000◦C. This means that high reaction rates can be achieved without expensive catalysts, and that gases such as natural gas can be used directly, or ‘internally reformed’ within the fuel cell, without the need for a separate unit.  This fuel cell type thus addresses all the problems and takes full advantage of the inherent simplicity of the fuel cell concept.  Nevertheless, the ceramic materials that these cells are made from are difficult to handle, so they are expensive to manufacture, and there is still quite a large amount of extra equipment needed to make a full fuel cell system. This extra plant includes air and fuel pre-heaters; also, the cooling system is more complex, and they are not easy to start up.  Despite operating at temperatures of up to 1000◦C, the SOFC always stays in the solid state. → Molten carbonate fuel cell (MCFC) has the interesting feature that it needs the carbon dioxide in the air to work.  The high temperature means that a good reaction rate is achieved by using a comparatively inexpensive catalyst – nickel. The nickel also forms the electrical basis of the electrode.  Like the SOFC it can use gases such as methane and coal gas (H2 and CO) directly, without an external reformer. However, this simplicity is somewhat offset by the 80 AUTOMOTIVE LABORATORY 5 nature of the electrolyte, a hot and corrosive mixture of lithium, potassium, and sodium carbonates. Table 1.1 demonstrates the summary of fuel cell types and application areas. Other Parts of a Fuel Cell System → On all but the smallest fuel cells the air and fuel will need to be circulated through the stack using pumps or blowers. Often compressors will be used, which will sometimes be accompanied by the use of intercoolers, as in internal combustion engines. → The direct current (DC) output of a fuel cell stack will rarely be suitable for direct connection to an electrical load, and so some kind of power conditioning is nearly always needed. This may be as simple as a voltage regulator, or a DC/DC converter. In combined heat and power (CHP) systems, a DC to AC inverter is needed, which is a significant part of the cost of the whole system. Electric motors, which drive the pumps, blowers, and compressors mentioned above, will nearly always be a vital part of a fuel cell system. Frequently also, the electrical power generated will be destined for an electric motor – for example, in motor vehicles. → The supply and storage of hydrogen is a very critical problem for fuel cells. Fuel storage will clearly be a part of many systems. If the fuel cell does not use hydrogen, then some form of fuel processing system will be needed. These are often very large and complex, for example, when obtaining hydrogen from petrol in a car. In many cases desulphurisation of the fuel will be necessary. → Various control valves, as well as pressure regulators, will usually be needed. In most cases a controller will be needed to coordinate the parts of the system. A special problem the controller has to deal with is the start-up and shutdown of the fuel cell system, as this can be a complex process, especially for high-temperature cells. 81 AUTOMOTIVE LABORATORY 5 → For all but the smallest fuel cells a cooling system will be needed. In the case of CHP systems, this will usually be called a heat exchanger, as the idea is not to lose the heat but to use it somewhere else. Sometimes, in the case of the higher-temperature cells, some of the heat generated in the fuel cell will be used in fuel and/or air pre-heaters. In the case of the PEM fuel cell, there is often the need to humidify one or both of the reactant gases. Figures Used to Compare Systems → For comparing fuel cell electrodes and electrolytes, the key figure is the current per unit area, always known as the current density. This is usually given in mA cm−2 though some Americans use A ft−2 (1.0mA cm−2 = 0.8A ft−2). → This figure should be given at a specific operating voltage, typically about 0.6 or 0.7 V. These two numbers can then be multiplied to give the power per unit area, typically given in mWcm−2. → Electrodes frequently do not ‘scale up’ properly. That is, if the area is doubled, the current will often not double. → Power Density = Power/Volume (kW m−3) Specific Power = Power/Mass (W kg−1) → In the automotive industry, the two key figures are the cost per kilowatt and the power density. In round figures, current internal combustion engine technology is about 1kWL−1 and $10 per kW. Such a system should last about 4000 h (i.e. about 1 h use each day for over 10 years). Advantages and Applications The most important disadvantage of fuel cells at the present time is the same for all types – the cost. However, there are varied advantages, which feature more or less strongly for different types and lead to different applications.  Efficiency. As is explained in the following chapter, fuel cells are generally more efficient than combustion engines whether piston or turbine based. A further feature of this is that small systems can be just as efficient as large ones. This is very important in the case of the small local power generating systems needed for combined heat and power systems.  Simplicity. The essentials of a fuel cell are very simple, with few if any moving parts. This can lead to highly reliable and long-lasting systems.  Low emissions. The by-product of the main fuel cell reaction, when hydrogen is the fuel, is pure water, which means a fuel cell can be essentially ‘zero emission’. This is their main advantage when used in vehicles, as there is a requirement to reduce 82 AUTOMOTIVE LABORATORY 5 vehicle emissions, and even eliminate them within cities. However, it should be noted that, at present, emissions of CO2 are nearly always involved in the production of hydrogen that is needed as the fuel.  Silence. Fuel cells are very quiet, even those with extensive extra fuel processing equipment. This is very important in both portable power applications and for local power generation in combined heat and power schemes. EXPERIMENTATION 83 AUTOMOTIVE LABORATORY 5 Nominal Current Istack (A) Measured Values Istack (A) Vstack (V) → How do you explain the characteristic curve? 84 Calculated Pstack (W) AUTOMOTIVE LABORATORY 5 85 AUTOMOTIVE LABORATORY 5 Effect of internal resistance on the characteristic curve of a fuel cell Nominal Istack (A) Istack (A) Measured Values Vstack (V) Vterminal (V) 0.0 0.00 8.90 8.95 0.2 0.21 8.19 8.25 0.5 0.49 7.94 7.99 1.0 1.00 7.65 7.67 1.5 1.51 7.42 7.42 2.0 2.02 7.22 7.20 3.0 3.00 6.88 6.81 5.0 5.02 6.38 6.23 7.0 6.99 5.89 5.67 10.0 9.95 5.21 4.89 86 AUTOMOTIVE LABORATORY 5 Nominal Istack (A) Measured Values Vstack (V) Istack (A) Vterminal (V) →Draw the two voltage-current characteristics Vstack=f(Istack) and Vterminal=f(Istack) and describe the shapes of both characteristic curve. →Describe the diverging shape of the characteristic curve with the fuel cell structure and suggest causes for it. →Consider the fuel cell as a real power supply and describe the make-up of internal resistance Rint. Divide it into two partial resistances and calculate the power losses due to these resistances at a stack current of 10 A. →Calculate the oxygen flow rate needed at an individual cell and the rate of water formation in order to produce an electric current of 10 A. Use a formula derived from Faraday’s laws for the determination of the substance changes. Then determine the theoretically needed volumetric air flow for the entire stack on the assumption that the usable oxygen portion in air is 20% (the system consists of 10-cell stack). Note: Perform the calculation at standard conditions (0°C, 1.01325 bar). The molecular standard volume is Vm = 22.4 L/mol; faraday constant F = 9.648 x 104 C/mol. Faraday’s First Law: m  ECE.I .t m: mass (g) ECE: electrochemical equivalent From Faraday’s Second Law, ECE can be written as: 87 AUTOMOTIVE LABORATORY 5 ECE  M z.F M: molecular mass (g) Efficiency of the fuel cell stack →Determine the stack efficiency ɳstack of this fuel cell by power balance. stack  Pout Vstack .I stack  Pin LHV .V H2 Note: The lower heating value (LHV) of hydrogen at standard conditions is 10.8 MJ/m3. Measured Value Calculation Istack (A) ɳstack Pstack (W) 0.00 0.00 0.00 0.20 0.37 1.66 0.52 0.51 4.13 1.00 0.53 7.51 1.51 0.55 10.89 1.99 0.53 13.85 3.01 0.51 19.60 5.01 0.48 30.16 7.00 0.45 39.41 10.00 0.41 51.20 88 AUTOMOTIVE LABORATORY 5 Measured Value Calculation ɳstack Istack (A) Pstack (W) →Draw the graphs of the functions stack  f ( I stack ) and Pstack  f ( I stack ) . →What important principles for the optimum design of fuel cells can be learned from these characteristic curves of power and efficiency? 89 R EARCH RESE H ENG GINE E TEST T SET T UP 1 CYLIN NDR, 4 STRO OKE, MULTI M -FUEL L,VCR (Com mputerizzed) Produ uct Code 2 240 Instrucction man nual Contents 1 Des scription 6 Commis ssioning 11 Components used 2 Spe ecifications 7 Software s’ manuals 12 components 3 Ins stallation req quirements 8 Troubles shooting 13 Warranty 4 Pac cking slip 9 Theory 5 Ins stallation 10 Experim ments Apex Innovations Description The setup consists of single cylinder, four stroke, Multi-fuel, research engine connected to eddy current type dynamometer for loading. The operation mode of the engine can be changed from diesel to Petrol or from Petrol to Diesel with some necessary changes. In both modes the compression ratio can be varied without stopping the engine and without altering the combustion chamber geometry by specially designed tilting cylinder block arrangement. The injection point and spark point can be changed for research tests. Setup is provided with necessary instruments for combustion pressure, Diesel line pressure and crank-angle measurements. These signals are interfaced with computer for pressure crank-angle diagrams. Instruments are provided to interface airflow, fuel flow, temperatures and load measurements. The set up has stand-alone panel box consisting of air box, two fuel tanks for duel fuel test, manometer, fuel measuring unit, transmitters for air and fuel flow measurements, process indicator and hardware interface. Rotameters are provided for cooling water and calorimeter water flow measurement. A battery, starter and battery charger is provided for engine electric start arrangement. The setup enables study of VCR engine performance for brake power, indicated power, frictional power, BMEP, IMEP, brake thermal efficiency, indicated thermal efficiency, Mechanical efficiency, volumetric efficiency, specific fuel consumption, A/F ratio, heat balance and combustion analysis. Labview based Engine Performance Analysis software package “Enginesoft” is provided for on line performance evaluation. Schematic arrangement 25-12-2010 Im240.docx Page 2 Apex Innovations Specifications Product Research Engine test setup 1 cylinder, 4 stroke, Multifuel (Computerized) Product code 240 Engine Type 1 cylinder, 4 stroke, water cooled, stroke 110 mm, bore 87.5 mm. Capacity 661 cc. Diesel mode: Power 3.5 KW, Speed 1500 rpm, CR range 12:1-18:1. Injection variation:0- 25 Deg BTDC Petrol mode: Power 4.5 KW @ 1800 rpm, Speed range 1200-1800 rpm, CR range 6:1-10:1, Spark variation: 070 deg BTDC Dynamometer Type eddy current, water cooled, with loading unit Propeller shaft With universal joints Air box M S fabricated with orifice meter and manometer Fuel tank Capacity 15 lit, Type: Duel compartment, with fuel metering pipe of glass Calorimeter Type Pipe in pipe Piezo sensor Combustion: Range 5000 PSI, with low noise cable Diesel line: Range 5000 PSI, with low noise cable Crank angle sensor Resolution 1 Deg, Speed 5500 RPM with TDC pulse. Data acquisition device NI USB-6210, 16-bit, 250kS/s. Piezo powering unit Make-Cuadra, Model AX-409. Digital voltmeter Range 0-20V, panel mounted Temperature sensor Type RTD, PT100 and Thermocouple, Type K Temperature Type two wire, Input RTD PT100, Range 0–100 Deg C, transmitter Output 4–20 mA and Type two wire, Input Thermocouple, Range 0–1200 Deg C, Output 4–20 mA Load indicator Digital, Range 0-50 Kg, Supply 230VAC Load sensor Load cell, type strain gauge, range 0-50 Kg Fuel flow transmitter DP transmitter, Range 0-500 mm WC Air flow transmitter Pressure transmitter, Range (-) 250 mm WC Software “Enginesoft” Engine performance analysis software Rotameter Engine cooling 40-400 LPH; Calorimeter 25-250 LPH Pump Type Monoblock Overall dimensions W 2000 x D 2500 x H 1500 mm Shipping details Gross volume 1.33m3, Gross weight 796kg, Net weight 639kg 25-12-2010 Im240.docx Page 3 Apex Innovations Installation requirements Electric supply Provide 230 +/- 10 VAC, 50 Hz, single phase electric supply with proper earthing. (Neutral – Earth voltage less than 5 VAC) • Provide 5A, three pin socket with switch (2 Nos.) for engine set up • Provide additional 5A, three pin sockets for computer and peripherals Water supply Continuous, clean and soft water supply @ 1000 LPH, at 10 m. head. Provide valve with 1” BSP hose terminal connection Computer IBM compatible with standard configuration. Typical configuration as follows: CPU: Pentium 300 GHz, RAM: Min. 512 MB, CD ROM drive, USB Port. OS: Windows XP + SP2. Monitor: Screen resolution 1280x1024. Space L3300 mm x W3200 mm x H1700 mm (Refer foundation drawings) Drain Provide suitable drain extension arrangement (Drain pipe 65 NB/2.5” size) Exhaust Provide suitable exhaust extension arrangement (Exhaust pipe 32 NB/1.25” size) Foundation Refer foundation drawings Foundation 240(1) and Foundation 240(2) Fuel, oil Diesel@10 lit. Petrol@10 lit. Lubrication Oil @ 3.5 lit. (20W40) 25-12-2010 Im240.docx Page 4 Apex Innovations Packing slip Total no. of boxes: 4, Volume: 2.54 m3, Gross weight: 791 kg. Net wt. 607 kg No 1 Description Size WxDxH mm Engine panel box assembly: Vol.m3 Gr wt Net wt kg kg 1830x585x685 0.74 144 90 965x560x375 0.20 36 15 0.17 40 22 Engine panel box structure Transmitters-Power supply panel Fuel DP transmitter Air transmitter NI -6210 device and wiring Engine Head with 2nos rod 2 Piping: Wiring PVC channels Air box conn. 2” hose nipple Starting kick/Handle Fuel measuring Glass tube Carburetor Water supply 1” hose pipe Pump outlet & Strainer, nipple Air duct Pipe 3 Engine wiring: 675x510x485 Piezo powering unit (Ax409) Dyna. loading unit (AX155) Load indicator (PIC 152) Digital voltmeter (SMP35) Piezo sensor Low noise cable Crank angle sensor Temperature sensors Load cell with nut bolts Pressure gauge Funnel Fuel caps Fuel pipes Spanner Allen keys & Tool kit Set of loose nut bolts & clips Battery charger 25-12-2010 Im240.docx Page 5 Apex Innovations Engine Software I/M- Apex CD NI-6210 Device CDs I/M Piezo sensor , Fuel DP, Air sensor, Dynamometer, Pump 4 Set up assembly : Open packing Engine + Dynamometer 1600x830x1075 1.43 571 480 Rotameters with piping Calorimeter & drain pipe Starter Assembly Battery Pump Installation • Unpack the box(es) received and ensure that all material is received as per packing slip. In case of short supply or breakage contact Apex Innovations / your supplier for further actions. • Remove the packings, paper boxes, wrappers from the components. • Refer the various photographs below and note locations of different components. • Install Engine setup assembly on the foundation and tighten the foundation bolts. The dynamometer body is clamped with its base by locking flat which is to be removed. There are jack bolts below the dynamometer which are raised upwards to restrict the swiveling motion. These bolts to be lowered to allow free motion of the body of the dynamometer. Inside the rotameters plastic rods are inserted to arrest the movement of respective floats. These rods are to be removed. • Keep Engine panel box structure near Engine setup assembly. Note the C type clamp provided for clamping the dynamometer loading unit. • Collect the Engine Panel Box. It is fitted with Fuel pipe (Glass), Manometer, Fuel DP transmitter, Air transmitter, Orifice for air metering, Transmitter panel(fitted with Power supply and five Temperature transmitters ), NI-6210 USB interface with cable for computer. • Check all terminal connections, component mounting and wiring screws • Fit the Engine panel box assembly on the Panel box structure with four bolts. 25-12-2010 Im240.docx Page 6 Apex Innovations • Collect Piezo powering unit (Ax409), Dynamometer loading unit (AX155), Load indicator (PIC152), Digital voltmeter (SMP35) from “Engine wiring” box. • Remove the covers of Piezo powering unit and Dynamometer loading unit and confirm that all components inside are at proper location and tightly fitted. Remove any packing material inside dynamometer loading unit. Confirm smooth working of loading knob on its front. The cover of the dynamometer loading unit is to be fitted after inserting the unit in the Engine panel support structure • Fit the Piezo powering unit (AX409) and put its clamps. Connect Electric supply cables and a 9 pin connector at Output • Fit load indicator (PIC152) and put its clamps. Connect 8 wires at respective terminals. • Fit Voltmeter (Meco) and put its clamps. Connect 4 wires at the back terminals. • Fit Dynamometer loading unit in the Engine panel structure after removing C clamp. Fit its cover and then fit the C clamp. • Remove the Exhaust pipe packed in wooden box placed inside “Engine piping” box and connect it between calorimeter exhaust inlet and engine exhaust outlet. • Connect Exhaust extension pipe at the outlet of calorimeter. Insert additional pipe in between and take the exhaust out of the room. • Collect the piping pieces form “Engine piping box”. Clean the pipes internally to remove any dust and particles. Complete the piping as per match marks as follows: o Connect Engine water inlet from engine cooling rotameter to water inlet on engine body. 25-12-2010 Im240.docx Page 7 Apex Innovations o Connect Engine water outlet. Connect Engine water outlet hose between the outlet pipe and engine body.. o Fit Strainer and hose nipple at the pump inlet and connect Water supply hose pipe. Connect this hose pipe to site water supply. o Fit Air box connection to air box and connect Air hose pipe from air box to engine. o The fuel pipe is put on engine and its one end is connected to fuel filter. Connect the other end in the engine panel at the brass hose tee in the fuel line. The fuel line is to be routed through the wiring channels. • Fit wiring PVC channel set. • Collect the wiring set from Sensors bag and fit 5 temp sensors at respective places. (i) RTD T1/T3 at the inlet water at pump outlet. (ii) RTD T2 at the Engine outlet water on the engine head. (iii) RTD T4 at the calorimeter water outlet. (iv) Thermocouple T5 at the Exhaust inlet of calorimeter and (v) Thermocouple T6 at the exhaust outlet of calorimeter. Route the wiring from PVC wiring channels. • Collect Electric supply cable packed in packing (named as Sensors) and connect L N E terminals to the transmitter panel at supply 230V. Connect its 3 pin (F) connector to Dynamometer loading unit at Supply. Connect male 3 pin connector to Elelctric supply available at the site. Route the cable through wiring channel. • Connect cable from Crank angle sensor, 4 pin round (F), to CA of Piezo powering unit. • Connect cable from Load cell, 4 pin round (F), to Load on transmitter panel. • Remove black cap on piezo sensor and connect piezo cable to the sensor. Connect other end of the piezo cable to Piezo powering unit at PZ1. • Connect dynamometer supply cable, 3 pin(M), to Output VDC of dynamometer loading unit. • Take out USB cable from NIUSB 6210 from Engine Panel and connect to Computer. The cable is short in length. A spare cable of extra length is also supplied. 25-12-2010 Im240.docx Page 8 Apex Innovations 25-12-2010 Im240.docx Page 9 Apex Innovations Commissioning • Remove top cover on the rocker box of the engine. Fill lubrication oil (SAE20W40 or equivalent) in the rocker box. About 3.5 lit oil is needed. To reach most of the oil to oil sump, it is necessary to wait for about 5 minutes, after filling the oil. Check the oil level by the dip stick provided in the crank case. • Two fuel tanks are provided on the top portion of the engine panel. You may fill two different fuels, for testing the fuels. Fill Diesel in one of the fuel tanks and Petrol in other tanks as marked on the tanks. Use Fuel funnel for filling. Put fuel caps on the fuel tanks. • Open the Fuel cock at the outlet of the fuel tank in which Diesel is filled. Note the Fuel in the glass fuel pipe. Remove complete air from the fuel pipe between Engine panel and Engine setup. • Air removal from fuel DP: Remove air bubbles from the fuel line connecting to Fuel DP transmitter. For removing the air loosen the Air vent on the fuel DP transmitter and allow some fuel to come out from it and then tighten it gently. • Fill water in the manometer up to “0” mark level. • Ensure that Jack bolts under dynamometer are lowered for free movement of the dynamometer body. • Switch on electric supply of the panel box and ensure that Piezo powering unit, load indicator and voltmeter are ON. • TDC adjustment: o Keep the Decompression lever on the rocker box in vertical position and rotate the flywheel slowly in clockwise direction (Viewed from dynamometer end) till the CA mark on the flywheel matches with the reference pointer provided on the engine body. This rotation movement should be unidirectional. 25-12-2010 Im240.docx Page 10 Apex Innovations o Check if the TDC light on the Piezo powering unit is lit. If not adjust the crank angle sensor as follows: o Loosen the four screws on the flange provided for clamping the crankangle sensor on the mounting bracket. o Ensure that crank angle sensor body is free to rotate about its axis. Rotate the sensor body slowly till the TDC light on the piezo powering unit glows. Ensure that the flywheel is adjusted for CA mark as explained above. o Clamp the four screws on the flange. • By using multipoint selector switch on the engine panel confirm that all voltage values are properly displayed. Convert the voltage values in to respective temperature reading using parameter chart pasted on the panel. The values displayed should show around ambient temperatures. • Confirm the load value on the load indicator is zero. Rotate the dynamometer body so that the nylon bush is pressing the load cell. Ensure that the load vlues on the load indicator are changing. • Compression Ratio adjustment: o Slightly loosen 6 Allen bolts provided for clamping the tilting block. o Loosen the lock nut on the adjuster and rotate the adjuster so that the compression ratio is set to “maximum”. Refer the marking on the CR indicator. o Lock the adjuster by the lock nut. o Tighten all the 6 Allen bolts gently. o You may measure and note the centre distance between two pivot pins of the CR indicator. After changing the compression ratio the difference (∆) can be used to know new CR. 25-12-2010 Im240.docx Page 11 Apex Innovations • Switch on the pump after providing electric supply to it and ensure water circulation through engine, calorimeter and dynamometer. • Keep the Load knob on the dynamometer loading unit at minimum position. • Engine starting (Diesel mode): o Ensure that all foundation bolts, propeller shaft bolts and Allen bolts of tilting block (of VCR arrangement) are properly tightened. o Ensure that Engine stop lever is free and can be pulled towards engine cranking side for stopping the engine. o For first start after installation, loosen the fuel inlet pipe to the injector. Crank the engine slowly (with Decompression lever in vertical position) till fuel starts dribbling out from the loosened nut. Then tighten the nut. o Ensure that Decompression lever (Decomp lever) is in horizontal position and CR is set at @ 17.5 to 18. o Start the engine ignition switch so that the engine will be cranked by battery. o If engine does not start you may check valve setting as explained in “Engine Valve setting”. 25-12-2010 Im240.docx Page 12 Apex Innovations • Keep water circulation on, Set @150 lph and 100 lph flow rates for engine cooling and calorimeter respectively. • Start the engine and allow it to run for 5 minutes in idling condition. Confirm that engine speed is displayed on Piezo powering unit. • Rotate the knob on dynamometer loading unit and gradually load the engine. Ensure that the load on the load indicator gradually increases. • Load the engine up to 12 kg allow it to run for 5 minutes. • Ensure that voltages displayed for all 5 temperature sensors are logically correct. • Stop the engine after releasing the load. • Ensure that engine is cooled before switching off the pump. • For software installation on the computer proceed to Software section Engine Valve setting This procedure to be followed only if engine does not start or pressure crankangle diagram shows some pressure values at the start of suction.) • Open the cover on the rocker box. Rotate the flywheel slowly and observe the rocker movement. The cranking side rocker is for inlet air and flywheel side rocker is for exhaust air. The “Engine fuel pump side end” of each rocker is pushed up by the valve rods below. Due to this the front end (injector side end) goes down to open the respective valves (Inlet/exhaust). For alternate rotation of flywheel at TDC position, both rockers move simultaneously. • Adjust the TDC mark marked as T on the flywheel with the pointer. (Note there are two marks one marked as CA and other as T. CA marking is to be used for crankangle sensor adjustment for PO diagram). 25-12-2010 Im240.docx Ensure that when we bring the Page 13 Apex Innovations flywheel near these markings both rockers should move i.e. piston is at the start of new cycle. • Refer the valve timing diagram on the engine panel. The Inlet valve should open 4.5 degree before TDC and exhaust valve should close 4.5 deg after TDC. Make a marking of @ 16 mm (4.5 degree) on both sides of TDC mark. • Rotate the flywheel in anticlockwise direction for 60 degrees and slowly rotate in clockwise direction up to the first mark before TDC (Here the inlet valve should open. Exhaust valve is already in open position i.e. rocker is in operated position). Adjust the Tappet clearance by using ring spanner no. 18 such that the clearance if any is removed and rocker just starts opening the inlet valve. • Further rotate the flywheel in clockwise direction to next marking of 4.5 degrees after TDC. At this position the exhaust valve should fully close. Adjust the tappet clearance so that there is no clearance in exhaust rocker. (Note: The decomp lever should be in horizontal position) • Ensure that inlet valve opens at 4.5 degree BTDC and exhaust valve closes 4.5 degree ATDC. 25-12-2010 Im240.docx Page 14 Apex Innovations Diesel to Petrol Removing Diesel Head • Switch off and disconnect electric supply of engine panel • Close the Fuel cock at the outlet of “Diesel tank”. • Keep Fuel cock on engine panel in “Tank” position. At fuel junction bracket, open the drain cock and collect the Diesel from fuel measuring unit and fuel line. Fill this fuel in the Diesel tank. • Disconnect the low noise cable from combustion chamber piezo sensor. • Disconnect the low noise cable from fuel line piezo sensor, mark it for identification. • Remove piezo sensor from the engine head and keep it at secured and safe place. • Disconnect the high pressure fuel pipe and overflow pipe connected to the injector. Connect these pipes to each other by inserting plastic pipe over high pressure metal pipe. • Disconnect air duct pipe from engine head. • Remove exhaust connection from engine head • Remove water outlet from engine head along-with water outlet temperature sensor. • Loosen and remove 4 nuts which clamp engine head to the linear block. (Use 9/16 spanner) • Remove push rods (2 nos.) Fitting Petrol Head • Adjust the compression ratio to 8:1 on petrol scale. • Check the condition of packing, if damaged use new head packing. Apply thin grease layer to head packing before use. • Inset 2 push rods for Petrol operation. These push rods are longer in length when compared with those for Diesel operation. • Remove the cover lid on the rocker box. Fit the head on linear block. Ensure that push rods are properly inserted in the engine head. This operation needs two persons to ensure proper assembly of push rods. Tighten the 4 nuts (Use 9/16W5 flat spanner). During tightening the nuts rotate the flywheel and ensure smooth movement of valve rods. Fit the cover lid. • Connect the Engine outlet water connection to the engine head (with outlet water sensor) • Connect exhaust connection to the engine head. • Remove carburetor from its support bracket and fit to engine head • Connect petrol pipe to carburetor 25-12-2010 Im240.docx Page 15 Apex Innovations • Connect the air duct pipe from air box to the carburetor. • Fit the piezo sensor in engine head and connect low noise cable to piezo sensor. • Remove spark cable from the spark plug at ignition coil and connect the cable to spark plug in the engine head. • Open the Fuel cock at the petrol tank outlet and collect @ 50 ml petrol from drain cock. Close the cock on petrol fuel tank and close the drain cock. • At fuel junction bracket, ensure that drain cock is closed. Petrol cock is opened and Diesel cock is closed. • Ensure Fuel cock on engine panel is in tank position. Open the Fuel cock at the outlet of Petrol tank • Ensure the CR is adjusted @ 8. Hand crank the engine to ensure smooth movement of the piston. • After all other preliminary checkups start the engine. If required, pull the choke on the carburetor during starting. Spark point adjustment Spark point adjustment to company setting • It is presumed that engine is set for Petrol operation. • Take the decompression lever to vertical position. • The company set Spark point is marked as “P” on the flywheel which is @ 10 Degrees before TDC (@ 3 teeth on the flywheel). 25-12-2010 Im240.docx Page 16 Apex Innovations • Rotate the flywheel to match the pointer with “P” mark. • To adjust the pick-up on the magneto, loosen the two clamping bolts on the pick-up mounting plate. Rotate the pickup and match the line mark on the pickup body with that of on the magneto. Clamp the pick-up mounting plate by tightening the two clamping bolts. • To run the engine with company set spark point, shift decompression lever to horizontal position and start it. Spark point adjustment to desired point • It is presumed that engine is set for Petrol operation. • The gear on the flywheel is with 125 teeth. For desired angle of spark point calculate no. of teeth. ( Example: For spark adjustment of 18 Degree BTDC , number of teeth are @ 6) • From the tooth near TDC mark, count number of teeth calculated above in clockwise direction (viewed from dynamometer) to mark the spark tooth. • Take the decompression lever to vertical position. Rotate the flywheel and mark the pointer with the spark tooth • Adjust the pick-up on the magneto by loosening two clamping bolts on the pick-up mounting plate. Rotate the pickup and match the line mark on the pickup body with that of on the magneto. Clamp the pick-up mounting plate by tightening the two clamping bolts. • Shift decompression lever to horizontal position and start the engine. • 25-12-2010 Im240.docx Page 17 Apex Innovations Petrol to Diesel Removing Petrol Head • Switch off and disconnect electric supply of engine panel • Close the Fuel cock at the outlet of “Petrol tank”. • Keep Fuel cock on engine panel in tank position. At fuel junction bracket, open the drain cock and collect the petrol from fuel measuring unit and fuel line. • Disconnect petrol pipe from carburetor and collect the petrol in that line from drain cock. • Fill the drained Petrol in the petrol tank. • Close the Petrol cock on the Fuel junction bracket. • Open the Diesel cock of Diesel Fuel tank and collect @ 50 ml Diesel from drain cock. Close the cock on Diesel fuel tank and close the drain cock. • Disconnect Spark plug and insert the Spark plug cable in a plug provided near ignition coil. (This plug is provided for supporting the plug cable) • Disconnect the piezo sensor low noise cable • Remove piezo sensor and keep it at secured and safe place. • Disconnect air duct pipe from carburetor • Remove carburetor from engine head (Use ¼ “ BSW spanner) and fit it to support bracket provided below throttle unit in the engine panel • Remove exhaust connection from engine head (Use ¼ “ BSW spanner). • Remove water outlet from engine head along-with temperature sensor (Use ¼ “ BSW spanner). • Loosen and remove 4 nuts which clamp engine head to the linear block. (Use 9/16W5 flat spanner) • Remove push rods (2 nos.) Fitting Diesel Head • Check the condition of packing, if damaged use new head packing. Apply thin grease layer to head packing.. • Inset push rods (2 Nos) for Diesel operation. These push rods are shorter in length when compared with those for petrol operation. • Remove the cover lid on the rocker box. Fit the head on linear block. Ensure that push rods are properly inserted in the engine head. This operation needs two persons to ensure proper assembly of push rods. Tighten the 4 nuts (Use 9/16W5 flat spanner). During tightening the nuts rotate the flywheel and ensure smooth movement of valve rods. Fit the cover lid. • Connect the Engine outlet water connection to the engine head (with outlet water temperature sensor) 25-12-2010 Im240.docx Page 18 Apex Innovations • Connect exhaust connection to the engine head. • Connect the air duct pipe from air box to the engine head. • At the delivery of the fuel pump, the high pressure metal pipe is connected to plastic pipe. Disconnect this connection and connect the high pressure pipe to inlet of the fuel injector. Connect the plastic pipe to the overflow of the injector. • Connect low noise cable of fuel line piezo sensor. • Fit the piezo sensor (Use spanner size 6-7) and connect low noise cable to piezo sensor. • At fuel junction bracket, ensure that drain cock is closed. Petrol cock is closed and Diesel cock is open. • Loosen the Vent plug on fuel pump. Ensure fuel cock on engine panel is in tank position. Open the Fuel cock at the outlet of Diesel tank • Close the vent on fuel pump as the Diesel comes out. • Ensure that the fuel injection is adjusted as described in “Injection point adjustment to company setting”. • Ensure the CR is adjusted @ 17-18. Hand crank the engine to ensure smooth movement of the piston. • After all other preliminary checkups start the engine. Injection point adjustment Injection point adjustment to company setting • It is presumed that engine is set for Diesel operation and Diesel fuel is available at fuel pump. 25-12-2010 Im240.docx Page 19 Apex Innovations • Remove the high pressure fuel pipe at the outlet of fuel pump. • Take the decompression lever to vertical position. • The company set injection point is marked “D” on the flywheel which is @ 23 Degrees before TDC (@ 8 teeth on the flywheel). • Rotate the flywheel (by hand) in clockwise direction and observe the fuel spillage from fuel pump. Note the spillage point on the flywheel. Note the difference between spillage point and company set injection point. • Turn the injection point adjusting nut in one direction@ ¼ turn. Check the difference between Fuel spillage point and company set injection point. If the difference is reduced repeat the adjustment in same direction. If the difference is increased rotate the adjusting nut in opposite direction. Repeat the adjustment till the difference is reduced to minimum. • To start the engine with company set injection point, connect the high pressure fuel pipe to the injection pump and shift decompression lever to horizontal position. Injection point adjustment to desired point (On line adjustment) • It is presumed that engine is running in Diesel mode and On-line Diesel injection plot is being displayed on the monitor using software. • Note the injection point displayed on the monitor. • Turn the injection point adjusting nut gradually and note its effect on Diesel injection plot. The Diesel injection plot shifts horizontally to retard/advance injection point depending upon the direction of rotation. Adjust the nut till desired injection point is obtained. 25-12-2010 Im240.docx Page 20 Apex Innovations Precautions • Use clean and filtered water; any suspended particle may clog the piping. • Circulate dynamometer and engine cooling water for some time after shutting down the engine. • Piezo Sensor Handling: o While engine is running ensure cooling water circulation for combustion pressure sensor / engine jacket. o Diaphragm of the sensor is delicate part. Avoid scratches or hammering. o A long sleeve is provided inside the hole drilled for piezo sensor. This sleeve is protecting the surface of the diaphragm. While removing the sensor, this sleeve may come out with the sensor and fall down or loose during handling. o Status of the sensor is indicated on the Piezo powering unit. Damages to the electronic parts of the sensor or loose connection are indicated as "open" or "Short" status on Piezo powering unit. 25-12-2010 Im240.docx Page 21 Apex Innovations Software Computer requirement CPU: Pentium 300 GHz, RAM: Min. 2GB or higher, DVD ROM drive, USB Port. Monitor: Colored. OS: Windows XP + SP2. Microsoft office 2007 or New version. Monitor: Screen resolution 1280x1024. Refer separate instruction manual supplied with software CD 25-12-2010 Im240.docx Page 22 Apex Innovations Setup constants 1 Pulses per revolution (360): No. of pulses received from crankangle sensor in one revolution. This value to be changed only when Crank angle sensor of different pulses per revolution is installed. 2 No. of cycles (10): Indicates number of successive cycles to be scanned at a stretch. One cycle for four stroke engine with 360 pulses per revolution scans 720 samples from one channel. 3 Fuel pipe diameter (mm) (12.40): Inside diameter of Glass fuel pipe. 4 Fuel measuring interval (sec) (60): Interval in which measurement of fuel is done after data logging is started. 5 Fuel display bias : There can be some difference in the Fuel CC value displayed on PO PV graphs screen with actual reading on the fuel pipe. This difference can be eliminated by adjusting fuel display bias value. 6 Orifice diameter (mm) (20): Diameter of orifice used for air flow metering. 7 Dynamometer arm length (mm) (185): Radial distance between dynamometer centre and the load cell position. 8 Speed scanning interval (ms) (2000): The speed value displayed on computer is calculated based on no. of pulses received during this interval (Interval is in milliseconds.) For smaller interval speed scanning is faster but with increased fluctuations. 9 Plot reference for cylinder pressure: The pressure crank angle diagram on the PO PV graphs screen can be lowered or raised by adjusting this value. 10 Plot reference for Diesel pressure: The Diesel injection pressure diagram on the PO PV graphs screen can be lowered or raised by adjusting this value. Theoretical constants 1 Use default values (Yes): If configured “Yes” default values are used. 2 Fuel density (kg/m^3) (830): Fuel density 3 Calorific value of fuel (KJ/Kg) (42000): Fuel calorific value 4 Orifice coef of discharge (0.60): Cd value of orifice used for air flow measurement. 5 Sp heat of exhaust gas (Kj/Kj.K) (1.00): Data required for heat balance calculations 6 Max. sp. heat. Of Exhaust Gas (KJ/Kg.k) (1.25): If data logging is done before attaining steady state the calculated specific heat value may be erractic. Hence this value is considered for heat balance calculations. 7 Min sp. heat of exhaust gas (KJ/Kg.k) (1.00): As above 8 Sp heat of water (KJ/Kg.K) (4.186): Standard data 9 Air density Kg/m^3): Calculated based on the configuration values. 25-12-2010 Im240.docx Page 23 Apex Innovations 10 Ambient temperature (Deg C): Enter ambient temperature. Graph X axis Load (Kg) (0 to 20 kg ): X axis scale for graph plotting the graphs for constant speed engines Plot details Diesel plot required: To be configured Yes if Diesel injection pressure sensor is used. • When engine is not started, On PO PV graphs tab, ensure that all 6 temperature readings displayed are near to ambient, and other readings like speed, load, air are zero. The bar graph displayed for fuel measuring indicates the level of fuel in the fuel pipe. • Start the engine and observe the values displayed on the screen. A typical screen is shown below: • Check engine operation at various loads and ensure respective signals on computer. 25-12-2010 Im240.docx Page 24 Apex Innovations Troubleshooting Note: 1 For component specific problems refer components’ manual 2 For wiring problems refer drawing “Wiring234”. Problems Possible causes / remedies Engine does not start Diesel mode: • Decompression lever in vertical position. Make it horizontal • Low Battery voltage: Recharge battery • No fuel injected: Remove air from air vent on the fuel pump • Clogged injector: Remove injector and check the fuel injection spray while engine is manually cranked. • VCR setting low: Set VCR to 17-18 • Fuel injection point disturbed: Set to company setting • Dynamometer loaded: Switch off dynamometer loading unit or adjust load to minimum • Improper valve setting: The valve setting procedure is described below. Petrol mode • Decompression lever in vertical position. Make it horizontal • Low Battery voltage: Recharge battery • Engine STOP switch in locked position. Release it • Spark plug damaged/short • VCR setting wrong : Set VCR to 8 • Spark timing disturbed: set to company settings • Dynamometer loaded: Switch off dynamometer loading unit or adjust load to minimum Dynamometer does not load the engine • Faulty/ loose wiring from dynamometer loading unit to dynamometer • No DC voltage at the outlet of dynamometer loading unit. Check DLU for loose connection • No free movement of dynamometer body due to raised jack bolts below dynamometer body • Water inlet outlet hoses connecting dynamometer body below the dynamometer may be very hard. 25-12-2010 Im240.docx Page 25 Apex Innovations Faulty air flow • Air hose leakage at connections between air box and engine. Faulty fuel flow • Air trap in pressure signal line to fuel transmitter • Improper closing of fuel cock. Software does not • Faulty or wrong USB port work • Virus in computer • Loose connections, improper earthing Faulty indicated power • TDC setting disturbed. Readjust TDC setting(refer commissioning). • Check configuration data Faulty pressure crank • Improper earthing angle diagram • Adjust Plot reference for cylinder pressure in setup constants such that suction stroke pressure just matches the zero line. • If peak pressure is just after TDC, TDC setting disturbed, readjust • If peak pressure shifts randomly with respect to TDC, coupling of crank angle sensor may be loose Faulty speed • Broken coupling of crank angle sensor indication Incorrect • Check the connection between thermocouple, RTD, temperature transmitters, Digital voltmeter. Note that yellow indication cable of thermocouple is positive and red is negative. • Open or damaged temperature sensor 25-12-2010 Im240.docx Page 26 Apex Innovations Theory Terminology Engine Cylinder diameter (bore) (D): The nominal inner diameter of the working cylinder. Piston area (A): The area of a circle of diameter equal to engine cylinder diameter (bore). A = π / 4 × D 2 Engine Stroke length (L): The nominal distance through which a working piston moves between two successive reversals of its direction of motion. Dead center: The position of the working piston and the moving parts, which are mechanically connected to it at the moment when the direction of the piston motion is reversed (at either end point of the stroke). Bottom dead center (BDC): Dead center when the piston is nearest to the crankshaft. Sometimes it is also called outer dead center (ODC). Top dead center (TDC): Dead center when the position is farthest from the crankshaft. Sometimes it is also called inner dead center (IDC). Swept volume (VS): The nominal volume generated by the working piston when travelling from one dead center to next one, calculated as the product of piston area and stroke. The capacity described by engine manufacturers in cc is the swept volume of the engine. Vs = A × L = π / 4 × D L 2 Clearance volume (VC): The nominal volume of the space on the combustion side of the piston at top dead center. Cylinder volume: The sum of swept volume and clearance volume. V = Vs + Vc Compression ratio (CR): The numerical value of the cylinder volume divided by the numerical value of clearance volume. CR 25-12-2010 Im240.docx = V / Vc Page 27 Apex Innovations Bore D Cylinder head Suction valve Intake or suction manifold Top dead center T.D.C. Piston Gudgeon or wrist pin Exhaust valve Exhaust manifold Clearance volume.Vc Cylinder volume’V’ Stroke volume.Vs Bottom dead center B.D.C. Cylinder Connecting rod Crankcase Crankshaft Crank pin Crank Important positions and volumes in reciprocating engine Four stroke cycle engine In four-stroke cycle engine, the cycle of operation is completed in four strokes of the piston or two revolutions of the crankshaft. Each stroke consists of 1800 of crankshaft rotation and hence a cycle consists of 7200 of crankshaft rotation. The series of operation of an ideal four-stroke engine are as follows: 1. Suction or Induction stroke: The inlet valve is open, and the piston travels down the cylinder, drawing in a charge of air. In the case of a spark ignition engine the fuel is usually pre-mixed with the air. 2. Compression stroke: Both valves are closed, and the piston travels up the cylinder. As the piston approaches top dead centre (TDC), ignition occurs. In the case of compression ignition engines, the fuel is injected towards the end of compression stroke. 3. Expansion or Power or Working stroke: Combustion propagates throughout the charge, raising the pressure and temperature, and forcing the piston down. At the end of the power stroke the exhaust valve opens, and the irreversible expansion of the exhaust gases is termed ‘blow-down’. 4. Exhaust stroke: The exhaust valve remains open, and as the piston travels up the cylinder the remaining gases are expelled. At the end of the exhaust stroke, 25-12-2010 Im240.docx Page 28 Apex Innovations when the exhaust valve closes some exhaust gas residuals will be left; these will dilute the next charge. Two stroke cycle engine In two stroke engines the cycle is completed in two strokes of piston i.e. one revolution of the crankshaft as against two revolutions of four stroke cycle engine. The two-stroke cycle eliminates the separate induction and exhaust strokes. 1. Compression stroke: The piston travels up the cylinder, so compressing the trapped charge. If the fuel is not pre-mixed, the fuel is injected towards the end of the compression stroke; ignition should again occur before TDC. Simultaneously under side of the piston is drawing in a charge through a springloaded non-return inlet valve. 2. Power stroke: The burning mixture raises the temperature and pressure in the cylinder, and forces the piston down. The downward motion of the piston also compresses the charge in the crankcase. As the piston approaches the end of its stroke the exhaust port is uncovered and blowdown occurs. When the piston is at BDC the transfer port is also uncovered, and the compressed charge in the crankcase expands into the cylinder. Some of the remaining exhaust gases are displaced by the fresh charge; because of the flow mechanism this is called ‘loop scavenging'. As the piston travels up the cylinder, the piston closes the first transfer port, and then the exhaust port is closed. Performance of I.C.Engines Indicated thermal efficiency (ηt): Indicated thermal efficiency is the ratio of energy in the indicated power to the fuel energy. η t = IndicatedPower / FuelEnergy η t (%) = IndicatedPower ( KW ) × 3600 × 100 FuelFlow( Kg / Hr ) × CalorificValue( KJ / Kg ) Brake thermal efficiency (ηbth): A measure of overall efficiency of the engine is given by the brake thermal efficiency. Brake thermal efficiency is the ratio of energy in the brake power to the fuel energy. η bth = BrakePower / FuelEnergy η bth (%) = BrakePower ( KW ) × 3600 × 100 FuelFlow( Kg / Hr ) × CalorificValue( KJ / Kg ) Mechanical efficiency (ηm): Mechanical efficiency is the ratio of brake horse power (delivered power) to the indicated horsepower (power provided to the piston). η m = BrakePower / IndicatedPower 25-12-2010 Im240.docx Page 29 Apex Innovations and Frictional power = Indicated power – Brake power Following figure gives diagrammatic representation of various efficiencies, Energy lost in exhaust, coolant, and radiation Energy lost in friction, pumping etc. Energy in fuel (A) IP (B) BP (C) Indicated thermal efficiency = B/A Brake thermal efficiency = C/A Mechanical efficiency = C/B Volumetric efficiency (ηv): The engine output is limited by the maximum amount of air that can be taken in during the suction stroke, because only a certain amount of fuel can be burned effectively with a given quantity of air. Volumetric efficiency is an indication of the ‘breathing’ ability of the engine and is defined as the ratio of the air actually induced at ambient conditions to the swept volume of the engine. In practice the engine does not induce a complete cylinder full of air on each stroke, and it is convenient to define volumetric efficiency as: Mass of air consumed ηv (%) = -------------------------------------------------------------------------mass of flow of air to fill swept volume at atmospheric conditions η v (%) = AirFlow( Kg / Hr ) × 100 π / 4 × D L(m ) × N ( RPM ) / n × NoofCyl × AirDen( Kg / m 3 ) × 60 2 3 Where n= 1 for 2 stroke engine and n= 2 for 4 stroke engine. 25-12-2010 Im240.docx Page 30 Apex Innovations Air flow: For air consumption measurement air box with orifice is used. AitFlow( Kg / Hr ) = C d × π / 4 × D 2 × 2 g × hwater × Wden / Aden × Aden × 3600 Where Cd = Coefficient of discharge of orifice D = Orifice diameter in m g = Acceleration due to gravity (m/s2) = 9.81 m/s2 h = Differential head across orifice (m of water) Wden = Water density (kg/m3) =@1000 kg/m3 Wair = Air density at working condition (kg/m3) = p/RT Where p= Atmospheric pressure in kgf/m2 (1 Standard atm. = 1.0332X104 kgf/m2) R= Gas constant = 29.27 kgf.m/kg0k T= Atmospheric temperature in 0k Specific fuel consumption (SFC): Brake specific fuel consumption and indicated specific fuel consumption, abbreviated BSFC and ISFC, are the fuel consumptions on the basis of Brake power and Indicated power respectively. Fuel-air (F/A) or air-fuel (A/F) ratio: The relative proportions of the fuel and air in the engine are very important from standpoint of combustion and efficiency of the engine. This is expressed either as the ratio of the mass of the fuel to that of the air or vice versa. Calorific value or Heating value or Heat of combustion: It is the energy released per unit quantity of the fuel, when the combustible is burned and the products of combustion are cooled back to the initial temperature of combustible mixture. The heating value so obtained is called the higher or gross calorific value of the fuel. The lower or net calorific value is the heat released when water in the products of combustion is not condensed and remains in the vapour form. Power and Mechanical efficiency: Power is defined as rate of doing work and equal to the product of force and linear velocity or the product of torque and angular velocity. Thus, the measurement of power involves the measurement of force (or torque) as well as speed. The power developed by an engine at the output shaft is called brake power and is given by Power = NT/60,000 in kW where T= torque in Nm = WR W = 9.81 * Net mass applied in kg. R= Radius in m N is speed in RPM 25-12-2010 Im240.docx Page 31 Apex Innovations Mean effective pressure and torque: Mean effective pressure is defined as a hypothetical pressure, which is thought to be acting on the piston throughout the power stroke. Power in kW = (Pm LAN/n 100)/60 in bar where Pm = mean effective pressure L = length of the stroke in m A = area of the piston in m2 N = Rotational speed of engine RPM n= number of revolutions required to complete one engine cycle n= 1 (for two stroke engine) n= 2 (for four stroke engine) Thus we can see that for a given engine the power output can be measured in terms of mean effective pressure. If the mean effective pressure is based on brake power it is called brake mean effective pressure (BMEP) and if based on indicated power it is called indicated mean effective pressure (IMEP). BMEP(bar ) = BrakePower( KW ) × 60 L × A × ( N / n) × NoOfCyl × 100 IMEP(bar ) = IndicatedPower ( KW ) × 60 L × A × ( N / n) × NoOfCyl × 100 Similarly, the friction means effective pressure (FMEP) can be defined as FMEP= IMEP – BMEP Basic measurements The basic measurements, which usually should be undertaken to evaluate the performance of an engine on almost all tests, are the following: 1 Measurement of speed Following different speed measuring devices are used for speed measurement. 1 Photoelectric/Inductive proximity pickup with speed indicator 2 Rotary encoder 2 Measurement of fuel consumption I) Volumetric method: The fuel consumed by an engine is measured by determining the volume flow of the fuel in a given time interval and multiplying it by the specific gravity of fuel. Generally a glass burette having graduations in ml is used for volume flow measurement. Time taken by the engine to consume this volume is measured by stopwatch. II) Gravimetric method: In this method the time to consume a given weight of the fuel is measured. Differential pressure transmitters working on hydrostatic head principles can used for fuel consumption measurement. 25-12-2010 Im240.docx Page 32 Apex Innovations 3 Measurement of air consumption Air box method: In IC engines, as the air flow is pulsating, for satisfactory measurement of air consumption an air box of suitable volume is fitted with orifice. The air box is used for damping out the pulsations. The differential pressure across the orifice is measured by manometer and pressure transmitter. 4 Measurement of brake power Measurement of BP involves determination of the torque and angular speed of the engine output shaft. This torque-measuring device is called a dynamometer. The dynamometers used are of following types: I) Rope brake dynamometer: It consists of a number of turns of rope wound around the rotating drum attached to the output shaft. One side of the rope is connected to a spring balance and the other to a loading device. The power is absorbed in friction between the rope and the drum. The drum therefore requires cooling. Brake power = ∏DN (W-S)/60,000 in kW where D is the brake drum diameter, W is the weight and S is the spring scale reading. II) Hydraulic dynamometer: Hydraulic dynamometer works on the principal of dissipating the power in fluid friction. It consists of an inner rotating member or impeller coupled to output shaft of the engine. This impeller rotates in a casing, due to the centrifugal force developed, tends to revolve with impeller, but is resisted by torque arm supporting the balance weight. The frictional forces between the impeller and the fluid are measured by the spring-balance fitted on the casing. Heat developed due to dissipation of power is carried away by a continuous supply of the working fluid usually water. The output (power absorbed) can be controlled by varying the quantity of water circulating in the vortex of the rotor and stator elements. This is achieved by a moving sluice gate in the dynamometer casing. III) Eddy current dynamometer: It consists of a stator on which are fitted a number of electromagnets and a rotor disc and coupled to the output shaft of the engine. When rotor rotates eddy currents are produced in the stator due to magnetic flux set up by the passage of field current in the electromagnets. These eddy currents oppose the rotor motion, thus loading the engine. These eddy currents are dissipated in producing heat so that this type of dynamometer needs cooling arrangement. A moment arm measures the torque. Regulating the current in electromagnets controls the load. Note: While using with variable speed engines sometimes in certain speed zone the dynamometer operating line are nearly parallel with engine operating lines which result in poor stability. 25-12-2010 Im240.docx Page 33 Apex Innovations 5 Measurement of indicated power There are two methods of finding the IHP of an engine. I) Indicator diagram: A dynamic pressure sensor (piezo sensor) is fitted in the cylinder head to sense combustion pressure. A rotary encoder is fitted on the engine shaft for crank angle signal. Both signals are simultaneously scanned by an engine indicator (electronic unit) and communicated to computer. The software in the computer draws pressure crank-angle and pressure volume plots and computes indicated power of the engine. Conversion of pressure crank-angle plot to pressure volume plot: The figure shows crank-slider mechanism. The piston pin position is given by x = r cos θ + l cos φ From figure r sin θ = l sin φ and recalling cos φ = 1 − sin 2 φ {1 − (r l ) sin θ } x = r  cos θ + l r  2 2 The binomial theorem can be used to expand the square root term: { [ ]} x = r cos θ + l / r 1 − 1 (r / l ) 2 sin 2 θ − 1 8 (r / l ) 4 sin 4 θ + ... 2 ….1 The powers of sin θ can be expressed as equivalent multiple angles: sin 2 θ = 1 / 2 − 1 / 2 cos 2θ sin 4 θ = 3 / 8 − 1 / 2 cos 2θ + 1 / 8 cos 4θ …….2 Substituting the results from equation 2 in to equation 1 gives { [ ]} x = r cos θ + l / r 1 − 1 (r / l ) 2 (1 / 2 − 1 / 2 cos 2θ ) − 1 8 (r / l ) 4 (3 / 8 − 1 / 2 cos 2θ + 1 / 8 cos 4θ ) + ... 2 2 The geometry of the engine is such that (r / l ) is invariably less than 0.1, in which case it is acceptable to neglect the (r / l )4 terms, as inspection of above equation shows that these terms will be at least an order of magnitude smaller than (r / l )2 terms. The approximate position of piston pin end is thus: 25-12-2010 Im240.docx Page 34 Apex Innovations [ { ]} x = r cos θ + l / r 1 − 1 ( r / l ) 2 (1 / 2 − 1 / 2 cos 2θ ) 2 Where r =crankshaft throw and Calculate l = connecting rod length. x using above equation; then (l + r − x ) shall give distance traversed by piston from its top most position at any angle II) Morse test: θ It is applicable to multi-cylinder engines. The engine is run at desired speed and output is noted. Then combustion in one of the cylinders is stopped by short circuiting spark plug or by cutting off the fuel supply. Under this condition other cylinders “motor” this cylinder. The output is measured after adjusting load on the engine to keep speed constant at original value. The difference in output is measure of the indicated power of cut-out cylinder. Thus for each cylinder indicated power is obtained to find out total indicated power. VCR Engines The standard available engines (with fixed compression ratio) can be modified by providing additional variable combustion space. There are different arrangements by which this can be achieved. Tilting cylinder block method is one of the arrangements where the compression ratio can be changed without change is combustion geometry. With this method the compression ratio can be changed within designed range without stopping the engine. Calculations • Brake power (kw): BP = 2πNT 60 x1000 = 2πN (WxR) 60000 = 0.785 xRPMx (Wx9.81) xArmlength 60000 BHP = • TxN 75x 60 Brake mean effective pressure (bar): BMEP = BPx 60 π / 4 xD xLx( N / n) xNoOfCylx100 2 n = 2 for 4 stroke n = 1 for 2 stroke • Indicated power (kw) :From PV diagram X scale (volume) 25-12-2010 1cm = ..m3 Im240.docx Page 35 Apex Innovations Y scale (pressure) 1cm = ..bar Area of PV diagram = ..cm2 workdone / cycle / cyl ( Nm ) = AreaofPVdi agram × Xscalefact or × Yscalefactor × 100000 IP = • workdone / cycle / cyl × ( N / n) × NoOfCyl 60 × 1000 Indicated mean effective pressure (bar): IPx 60 π / 4 xD xLx ( N / n) xNoOfCylx100 IMEP = • 2 Frictional power (kw): FP = IP − BP FHP = IHP − BHP BHP = IHP − FHP • Brake specific fuel consumption (Kg/kwh): BSFC = • • • Brake Thermal Efficiency (%): BThEff = BP × 3600 × 100 FuelFlowInKg / hr × CalVal BThEff = IThEff × MechEff BHP OR 100 FuelHP Indicated Thermal Efficiency (%): IThEff = IP × 3600 × 100 FuelFlowInKg / hr × CalVal IThEff = BThEff × 100 MechEff Mechanical Efficiency (%): MechEff = • FuelflowIn kg / hr BP BP × 100 IP Air flow (Kg/hr): AirFlow = Cd × π / 4 × d 2 2 gh × (Wden / Aden ) × 3600 × Aden • Volumetric Efficiency (%): VolEff = 25-12-2010 AirFlow × 100 TheoreticalAirFlow Im240.docx Page 36 Apex Innovations = • Air fuel ratio: A/ F = • AirFlow × 100 π / 4 × D × Stroke × ( N / n) × 60 × NoOfCyl × Aden 2 AirFlow FuelFlow Heat Balance (KJ/h): a) HeatSuppli edbyFuel = FuelFlow × CalVal b) HeatEquiva lentToUsef ulWork = BP × 3600 HeatEquivalentToUsefulWorkIn% = C) HeatEquivalentToUsefulWork × 100 HeatSuppliedByFuel HeatInJacketCoolingWater = F 3 × C PW × (T 2 − T1) HeatInJacketCoolingWaterIn% = HeatInJacketCoolingWater × 100 HeatSuppliedByFuel d) Heat in Exhaust (Calculate CPex value): C P ex = F 4 × C PW × (T 4 − T 3) ..KJ / Kg 0 k ( F1 + F 2) × (T 5 − T 6) Where, Cpex Specific heat of exhaust gas kJ/kg0K Cpw Specific heat of water kJ/kg0K F1 Fuel consumption kg/hr F2 Air consumption kg/hr F4 Calorimeter water flow kg/hr T3 Calorimeter water inlet temperature 0 K T4 Calorimeter water outlet temperature 0 K Exhaust gas to calorimeter inlet temp. 0 K Exhaust gas from calorimeter outlet temp. 0 K T5 T6 HeatInExha ust ( KJ / h) = ( F 1 + F 2) × C P ex × (T 3 − Tamb ) HeatInExhaust % = HeatInExhaust × 100 HeatSuppliedByFuel e) Heat to radiation and unaccounted (%) = HeatSuppliedByFuel (100%) − {( HeatEquivalentToUsefulWork (%) + HeatInJacketCoolingWater (%) + HeatToExhaust (%)} 25-12-2010 Im240.docx Page 37 Apex Innovations Experiments 1 Study of VCR engine performance (Computerized mode) Object To study the performance of 1 cylinder, 4 stroke, Diesel engine connected to eddy current dynamometer in computerized mode. Adjustment of the compression ratio • Slightly loosen the 6 nos. vertical Allen (socket headed) bolts provided on both sides of the tilting cylinder block. • Loosen the lock nut of the Adjuster and rotate the Adjuster by using spanner for tilting the cylinder block. • Adjust the desired compression ratio by referring the scale provided on the CR indicator (near the Adjuster) • Tighten the lock nut of the Adjuster. • Gently tighten the vertical Allen bolts (6 nos.). Procedure • Ensure that all the nut bolts of engine, dynamometer, propeller shaft, base frame are properly tightened. • Ensure that sufficient lubrication oil is present in the engine sump tank. This can be checked by marking on the level stick • Ensure sufficient fuel in fuel tank. Remove air in fuel line, if any. • Switch on electric supply and ensure that PPU (Piezo powering unit /AX-409), DLU (Dynamometer loading unit/AX-155), Load indicator and Voltmeter are switched on. • Start Computer and open "EngineSoft" (Double click "EngineSoft" icon on the desktop) Select "Engine Model" open "Configure" in View. Check configuration values & system constants with the values displayed on engine setup panel. "Apply" the changes, if any. Click on "PO- PV Graphs" tab. • Start water pump. Adjust the flow rate of "Rotameter (Engine)" to 250-350 LPH and "Rotameter (Calorimeter)" to 75-100 LPH by manipulating respective globe valves provided at the rotameter inlet. Ensure that water is flowing through dynamometer at a pressure of @ 0.5 to 1 Kg/cm2. • Keep the DLU knob at minimum position. • Change the Fuel cock position from "Measuring" to "Tank" • Start the engine by hand cranking and allow it to run at idling condition for 45 minutes. • Click on "Scan Start" on the monitor 25-12-2010 Im240.docx Page 38 Apex Innovations • Ensure that Speed, Temperatures and Manometer reading are correctly displayed on the PC. These readings should tally with those displayed on the engine panel. • Increase the load on the engine by rotating knob on the DLU and confirm the load reading on the indicator and computer are same. • Adjust DLU knob and to set 0.5 kg load on Load Indicator. Wait for 3 mins., ensure that load is constant during this period. Change the Fuel cock position from "Tank" to "Measuring". Click "Log on" on. The fuel metering is ON for next 60 seconds. During first 30 seconds enter engine water flow, calorimeter jacket cooling water flow in LPH (and compression ratio for VCR engine). Click OK after recording fuel reading. Enter the file name under which the records to be stored. The first reading data is now saved. Change the Fuel cock position from "Measuring" to "Tank". • Adjust DLU knob and to set 3 kg load on Load Indicator. Wait for 3 mins., ensure that load is constant during this period. Change the Fuel cock position from "Tank" to "Measuring". Click "Log on" on. The fuel metering is ON for next 60 seconds. During first 30 seconds enter engine water flow, calorimeter jacket cooling water flow in LPH (and compression ratio for VCR engine). Click OK after recording fuel reading. The second reading data is now saved. Change the Fuel cock position from "Measuring" to "Tank". • Repeat above step for various loads e.g. 6, 9,12,15,18 kg. (For VCR engine do not exceed 12 Kg load.) • After finishing all the readings remove the load on the engine by DLU, Click "Scan Stop" on PC. • Stop the engine by pressing engine stop lever. Allow the water to circulate for about 5 minutes for engine cooling and then Stop the pump. • Click "File Open" on PC, Select the File under which the readings are stored and click "OK". On all the screens the first reading (of 0.5kg) is shown. To view next readings click "Next Data". • The results are displayed on all the three screens. For printing the results click "Print" and select appropriate option. • Click "File Close" after printing & checking. Click "Exit" and then Shut Down the computer. 25-12-2010 Im240.docx Page 39 Apex Innovations Enginesoft Configuration data Setup constants (Default values) Diesel Petrol 1 Pulses per revolution 360 360 2 No. of cycles 10 10 3 Fuel pipe diameter (mm): 12.40 12.40 4 Fuel measuring interval (sec): 60 30 5 Fuel display bias: 0 0 6 Orifice diameter (mm): 20 20 7 Dynamometer arm length (mm): 185 185 8 Speed scanning interval (ms): 2000 2000 9 Plot reference for cylinder pressure: 4 4 10 Plot reference for Diesel pressure: 4 - 1 Use default values Yes Yes 2 Fuel density (kg/m^3) 830 740 3 Calorific value of fuel (KJ/Kg) 42000 44000 4 Orifice coef of discharge 0.6 0.6 5 Sp heat of exhaust gas (Kj/Kj.K) 1.0 1.0 6 Max. sp. heat. Of Exhaust Gas (KJ/Kg.k) 1.25 1.25 7 Min. sp. heat. Of Exhaust Gas (KJ/Kg.k) 1.00 1.00 8 Sp heat of water (KJ/Kg.K) 4.186 4.186 9 Air density Kg/m^3) 1.174 1.174 10 Ambient temperature (Deg C) 27 27 Load (Kg) 0-20 kg - Speed RPM - 1000-2000 Diesel plot reqd Yes No Research Research diesel engine petrol engine Power(KW) 3.5 4.5 Maximum speed rpm 1500 1800 Cylinder bore (mm) 87.5 87.5 Stroke(mm) 110 110 Connecting rod length (mm) 234 234 Set up Theoretical constants Graph X axis Engine Model 25-12-2010 Im240.docx Page 40 Apex Innovations Compression ratio 17.5 8 Stroke type 4 stroke 4 stroke Number of cylinder 1 1 Speed type Constant Variable Cooling type Water Water Fuel Diesel Petrol Compression ratio Variable Variable Swept volume 661.5 661.5 25-12-2010 Im240.docx Page 41 Apex Innovations 2 Study of VCR engine performance (Manual mode) Object To study the performance of 1 cylinder, 4 stroke, Diesel engine connected to eddy current dynamometer in manual mode Adjustment of the compression ratio • Refer Expt no. 1 and adjust VCR for desired compression ratio. Procedure • Ensure cooling water circulation for eddy current dynamometer and piezo sensor, engine and calorimeter. • Start the set up and run the engine at no load for 4-5 minutes. • Gradually increase the load on the engine by rotating dynamometer loading unit. • Wait for steady state (for @ 3 minutes) and collect the reading as per Observations provided in “Cal234” worksheet in “Engine.xls”. • Gradually decrease the load. • Fill up the observations in “Cal234” worksheet to get the results and performance plots. 25-12-2010 Im240.docx Page 42 Apex Innovations 3 Study of Pressure volume plot and indicated power Object To draw pressure–crank angle plot, pressure volume plot and calculate indicated power of the engine. Procedure • Run the engine set up at any load and store the observation in a data file or use previously stored data file in “Enginesoft” for indicated power calculation. • Export the data file in ms excel worksheet. The pressure crank angle and volume data is available in excel. • Refer “IP_cal” worksheet in “Engine.xls”. The sample worksheet shows pressure crank angle plot, pressure volume plot and indicated power calculation. The worksheet is for single cylinder four stroke engine with 180 observations per revolution. • Copy the pressure readings from exported data file in to the IP _cal worksheet at the respective crank angle. • Observe the Pressure crank angle diagram, pressure volume diagram and indicated power value. (The calculations are explained in theory part). 25-12-2010 Im240.docx Page 43 Apex Innovations 4 Maximum power test at different compression ratio Object To study the maximum power generated by VCR engine at various compression ratios. Adjustment of the compression ratio • Adjust the compression ratio as explained in experiment no.1 Performance test • Ensure cooling water circulation for eddy current dynamometer and engine and calorimeter. • Start the set up and run the engine at no load for 4-5 minutes. • Gradually increase the load on the engine by rotating knob on dynamometer loading unit till the engine is fully loaded. (As load is increased further the speed drops significantly.) • Note the reading as per Observations provided in “Cal234” worksheet in “Engine.xls”. • Gradually decrease the load. • Change the compression ratio for next observation and repeat above steps. • Fill up the observations in “Cal234” worksheet to get the results and performance plots. 25-12-2010 Im240.docx Page 44 Apex Innovations 5 BSFC and brake thermal efficiency test at different CR Object To study the BSFC and brake thermal efficiency of VCR engine at various compression ratios. Adjustment of the compression ratio • Adjust the compression ratio as explained in experiment no.1 Performance test • Ensure cooling water circulation for eddy current dynamometer and engine and calorimeter. • Start the set up and run the engine at no load for 4-5 minutes. • Gradually increase the load on the engine by rotating knob on dynamometer loading unit to @80% of load (Refer experiment 3 for full load observed at the set compression ratio). • Note the reading as per Observations provided in “Cal234” worksheet in “Engine.xls”. • Gradually decrease the load. • Change the compression ratio for next observation and repeat above steps. Fill up the observations in “Cal234” worksheet to get the results and performance plots. 25-12-2010 Im240.docx Page 45 Apex Innovations 6 Study of valve timing diagram Object To study valve timing diagram Valve Timing Diagram Engine Kirloskar (TV1) 1Cylinder, 4Stroke, Diesel 1 Inlet valve opens before TDC : 4.5 0 2 Inlet valve closes after BDC : 35.5 0 3 Fuel injection starts before TDC : 23 0 4 Exhaust valve opens before BDC : 35.5 0 0 5 Exhaust valve closes after TDC : 4.5 2 Expansion Compression 1 TDC 5 Induction Exhaust 3 4 BDC Procedure • Switch off the electric supply of the panel box • Open the cover on the engine head to see the rocker arms. • Lift up the decompression lever. • Note the TDC mark provided on the flywheel. (Also refer the valve timing diagram). • Slowly rotate the flywheel in clockwise direction looking from dynamometer side. Identify inlet valve and exhaust valve rocker arms • Observe the movement of rocker arms and understand the valve opening and closing. To observe fuel injection it is necessary to remove fuel injector. 25-12-2010 Im240.docx Page 46 Apex Innovations Components used Components Details Engine Make Kirloskar, Type 1 cylinder, 4 stroke Diesel, water cooled, Model TV1, stroke 110 mm, bore 87.5 mm. 661 cc, CR 17.5, Modified to VCR engine CR range 12 to 18 with additional head for petrol Dynamometer Make Saj test plant Pvt. Ltd., Model AG10, Type Eddy current Dynamometer Loading Make Apex, Model AX-155. Type constant speed, unit Supply 230V AC. Propeller shaft Make Hindustan Hardy Spicer, Model 1260, Type A Manometer Make Apex, Model MX-104, Range 100-0-100 mm, Type U tube, Conn. 1/4`` BSP hose back side, Mounting panel Fuel measuring unit Make Apex, Glass, Model:FF0.012 Piezo sensor Make PCB Piezotronics, Model SM111A22, Range 5000 psi, Diaphragm stainless steel type & hermetic sealed White coaxial teflon cable Make PCB piezotronics, Model 002C20, Length 20 ft, Connections one end BNC plug and other end 10-32 micro Crank angle sensor Make Kubler-Germany Model 8.3700.1321.0360 Dia: 37mm Supply Shaft Size: Voltage Size 5-30V 6mmxLength DC, Output 12.5mm, Push Pull (AA,BB,OO), PPR: 360, Outlet cable type axial with flange 37 mm to 58 mm Data acquisition device NI USB-6210 Bus Powered M Series, Piezo powering unit Model AX-409. Temperature sensor Make Radix Type K, Ungrounded, Sheath Dia.6mmX110mmL, SS316, Connection 1/4"BSP (M) adjustable compression fitting Temperature sensor Make Radix, Type Pt100, Sheath Dia.6mmX110mmL, SS316, Connection 1/4"BSP(M) adjustable compression fitting Temperature transmitter Make Wika, model T19.10.3K0-4NK-Z, Input Thermocouple (type K), output 4-20mA, supply 25-12-2010 Im240.docx Page 47 Apex Innovations 24VDC, Calibration: 0-1200deg.C. Temperature transmitter Make Wika, Model T19.10.1PO-1 Input RTD(Pt100), output 4-20mA, supply 24VDC, Calibration: 0-100°C Load sensor Make Sensotronics Sanmar Ltd., Model 60001,Type S beam, Universal, Capacity 0-50 kg Load indicator Make Selectron, model PIC152, 85 to 270VAC, retransmission output 4-20 mA Power supply Make Meanwell, model S-15-24, O/P 24 V, 0.7 A Digital voltmeter Make Meco, 3.1/2 digit LED display, range 0-20 VDC, supply 230VAC, model SMP35 Fuel flow transmitter Make Yokogawa, Model EJA110-EMS-5A-92NN, Calibration range 0-500 mm H2O, Output linear Air flow transmitter Range (-) 250 mm WC Rotameter Make Eureka Model PG 5, Range 25-250 lph, Connection ¾” BSP vertical, screwed, Packing neoprene Rotameter Make Eureka Model PG 6, Range 40-400 lph, Connection ¾” BSP vertical, screwed, Packing neoprene Pump Make Kirloskar, Model Mini 18SM, HP 0.5, Size 1” x 1”, Single ph 230 V AC 25-12-2010 Im240.docx Page 48 Apex x Innovatio ons Co omponen nts’ manu uals Rotametter (PG series) s Rotam meter work ks on the prrinciple of v variable area. Float is free to t move up & down in a tapered m measuring glass g tube. Upwa ard flow cau uses the floa at to take up u a position n in which the buoyancy forces f and the weightt are balan nced. The vertic cal position n of the flo oat as indiicated by scale s is a meas surement off the instanttaneous flow w rate. Tech hnical spe ecification ns Mode el PG-1 to 21 1 Make e Eureka Flow Rate Max. 000 Lph 100 to 400 Packiing/Gaskets s Neoprene Meas suring tube Borosilicate glass Float 316SS Cove er Glass Accuracy +/-2% fulll flow ge ability Rang 10:1 Scale e length 175-200mm. Max. Temp. 2000C Conn nection Flanged an nd Threaded d, Vertical Principle of operation The rotameter r valves v must be opened slowly and carefully to o adjust the e desired flo ow rate. A sudden jumping of the t float, wh hich may cause damage e to the mea asuring tube e, mustt be avoided d. F Fig.1 Edge E The upper edge e of the flo oat as shown in fig. 1 indicates s the rate of flow. Fo or alignment a line marked R.P. is provided on the scale s which should coincide with th he red liine provided d on measurring tube att the bottom m. 25 12 2 2010 Im2 240 doc Page 49 Apex Innovations Maintenance When the measuring tube and float become dirty it is necessary to remove the tube and clean it with a soft brush, trichloroethylene or compressed air. Dismantling of the measuring tube • Shut off the flow. • Remove the front and rear covers. • Unscrew the gland adjusting screws, and push the gland upwards incase of bottom gland and downwards incase of top gland. Then remove the glass by turning it to and fro. Care should be taken, not to drop down the glands. Float or float retainers. The indicating edge of the float should not be damaged. Fitting of the measuring tube Normally the old gland packing is replaced by new ones while fitting back the measuring tube. • Put the glands first in their position and then put the packing on the tube. • Insert the tube in its place. • Push the glands downwards and upwards respectively and fix them with the gland adjusting screws. • Tighten the gland adjusting screws evenly till the gap between the gland and the bottom plate is approximately 1mm. In case, after putting the loflometer into operation, still there is leakage, then tighten the gland adjusting screw till the leakage stops. • Fix the scale, considering the remark given in the test report. • Fix the front and rear covers. Troubleshooting Problem Check Leakage on glands Replace gland packing Showing high/low flow rate than Consult manufacturers expected Showing correct reading initially but Replace float starts showing high reading after Incase of gases, check also leakage few days Showing correct reading initially but Clean the rotameter by suitable solvent or starts showing high reading after soft brush some months. Fluctuation of float Maintain operating pressure as mentioned in test report. Frequent breakage of glass tube Use loflometer to accommodate correct flow rate. 25-12-2010 Im240.docx Page 50 Apex Innovations Maintain operating pressure below pressure rating of the tube. Check piping layout. Manufacturer’s address Eureka Industrial Equipments Pvt. Ltd. 17/20, Royal Chambers, Paud Road, Pune – 411 038. Email: [email protected] 25-12-2010 Im240.docx Page 51 Apex Innovations Pump (Self priming) The centrifugal pumps designed for pumping water and many similar applications. The pump & the motor are designed for continuous operations. Technical specifications Model MINI-18SM Make Kirloskar Supply 230 VAC, Single phase Total Head Max. 6-18 meter Discharge 1650-720 Lph Connection 20 x 20mm Water seal Mechanical Pump Unit CI. Power Rating 0.18Kw/0.25hp Type of Motor Capacitor starts and run Insulation ‘B’ class Rating Continuous Impeller H.T. Brass Delivery casing Cast Iron Motor Body Cast Iron Shaft Carbon steel Priming The pump is of self priming model. It is only essential to fill about 300ml. of water into the casing once during installation and shut the filler cap tightly. After switching the pump on, during the first operation it will have to remove the air in the suction pipe and will take min. 2 minutes before the water begins to flow. During consecutive operations you will get water immediately on switching the pump. Troubleshooting Problem Check Motor does not rotate Check power supply. Remove fan cover and check free rotation of fan along with shaft.(By hand) Check supply voltage. Replace condenser. Capacity the decreases pump satisfactorily. is after running The inlet of suction pipe should be at least 2” below the water level. Clean the pipe. Reduce the total head. 25-12-2010 Im240.docx Page 52 Apex Innovations Check the pipe for leakage and correct it. Change to the recommended size. Pump over loaded. (Takes Select suitable monoblock pump. more amps or fuse goes off) Reduce the total head. Leaking mechanical seal. Lap the running faces or change seal. Pump gets jammed Remove fan cover and rotate fan by hand. Pump should run for a few minutes at least once in two days. Pump does not lift water Fill water till it flows continuously in air cock. Check pipe for leakages. Use Teflon tape for joints. Clean pipes and reduce the bends. Change or re-fit the seal. Tighten the air cock head: if damaged replace it. Manufacturer’s address Kirloskar Brothers Ltd., Ujjain Road, Opp. Railway Station, Dewas – 455 001. E-mail: [email protected] 25-12-2010 Im240.docx Page 53 Apex x Innovatio ons E Engine Tech hnical spe ecification ns Mode el TV1 Make e Kirloskar O Oil Engines Type Four stroke e, Water ed, Diesel coole No. of o cylinder One Bore 87.5 mm ke Strok 110 mm Comb bustion prin nciple Compression ignition Cubic c capacity 0.661 literrs Comp pression rattio 3 port 17.5:1 Peak pressure 77.5 kg/cm m2 ction of rotation Direc Clockwise (Looking from flywheel en nd side) Max. speed 2000 rpm Min. idle speed 750 rpm Min. operating speed 1200 rpm Fuel timing for std. s engine 230 BTDC Valve e timing Inlet opens BTDC 4.50 Inlet closes ABDC 35.50 Exhaust opens o BBDC C 35.50 Exhaust closes c ATDC C 4.50 Valve e clearance Inlet 0.18 mm Valve e clearance Exhaust 0.20 mm Bump ping clearan nce 0.046” – 0 0.052” Lubricating syste em Forced fee ed system Powe er rating 1. Continuous 7/1500 hp p/rpm 2. Interm mittent 7.7/1500 h hp/rpm Brake e mean effe ective Press sure at 1500 0 rpm 6.35 kg/cm m2 Lubricating oil pu ump Gear type Lub. oil pump de elivery 6.50 lit/min. Sump p capacity 2.70 liter Lub. Oil consumption 1.5% norm mally exceed d of fuel Conn necting rod length 234 mm 25 12 2 2010 Im2 240 doc Page 54 Apex Innovations Overall dimensions 617 L x 504 W x 877 H Weight 160 kgs Manufacturer’s address Kirloskar Oil Engines Ltd. Dealer: Laxmanrao Kirloskar Road, Ashwini Enterprise Khadki, Pune – 411 003. Kolhapur. 25-12-2010 Im240.docx Page 55 Apex x Innovatio ons Crank a angle se ensor Tech hnical spe ecification ns Make e Kublerr Mode el 8.3700 0.1321.0360 Supp ply voltage 5-30VDC Output p (AA,BB,OO) Push pull PPR 360 Outle et Cable typ pe axial Encoder Diamete er Dia. 37 7, Shaftt size Dia.6m mm x length h12mm Weight 120 gm m Man nufacturerr’s address Kueb bler – Germa any an supplier: India Rajd deep Automa ation Pvt. Lttd. Surv vey No. 143, 3rd floor, Sinh hgad Road, Vadgaon V Dh hayari, Pune e – 411 041 1. 25 12 2 2010 Im2 240 doc Page 56 Apex Innovations Piezo sensor Introduction These miniature sensor series are intended for general purpose pressure measurements. Models SM111A22 and M108A02 are designed for applications where acceleration compensation is not required. This versatile compression, transducer combustion, series is explosion, designed pulsation, for dynamic cavitations, measurement blast, of pneumatic, hydraulic, fluidic and other such pressures. Technical specifications Sensor name Dynamic pr. transducer With built in amplifier Make PCB Piezotronics, INC. Model M111A22 Range, FS (5V output) 5000 psi Useful range (10V output) 10000 psi Maximum pressure 15000 psi Resolution 0.1 psi Sensitivity 1 mV/psi Resonant frequency 400 kHz Rise time 2 µs Discharge time constant 500 s Low frequency response (-5%) 0.001 Hz Linearity (Best straight line) 2% Output polarity Positive Output impedance 100 ohms Output bias 8-14 volt Acceleration sensitivity 0.002 psi/g Temperature coefficient 0.03 %/0F Temperature range -100 to +275 0F Flash temperature 3000 0F Vibration / Shock 2000 / 20000 g peak Ground isolation No (2) Excitation (Constant current) 2 to 20 mA Voltage to current regulator +18 to 28 VDC Sensing geometry Compression Sensing element Quartz Housing material 17.4 SS Diaphragm Invar Sealing Welded hermetic 25-12-2010 Im240.docx Page 57 Apex Innovations Electric connector 10-32 coaxial jack Mounting thread M7 x 0.75 pitches Weight (with clamp nut) 6 gm Cable model 002C20 white coaxial cable Principle of operation Dynamic pressure transducer: It is necessary only to supply the sensor with a 2 to 20 mA constant current at +20 to +30 VDC through a current – regulating diode or equivalent circuit. Most of the signal conditioners manufactured by PCB have adjustable current features allowing a choice of input currents from 2 to 20 mA. In general, for lowest noise (best resolution), choose the lower current ranges. When driving long cables (to several thousand feet), use the higher current, up to 20 mA maximum. Troubleshooting Problem Check No signal • Remove sensor and clean by dampened cloth Sensor damaged or ceases to • Return the equipment to company for repair operate Calibration 1. Piezoelectric sensors are dynamic devices, but static calibration techniques can be employed if discharge time constants are sufficiently long. Generally, static calibration methods are not employed when testing sensors with a discharge time constant that is less than several hundred seconds. 2. Direct couple the sensor to the DVM readout using a T-connector from the “Xducer” jack or use the model 484B in the calibrate mode. 3. Apply pressure with a dead weight tester and take reading quickly. Release pressure after each calibration point. 4. For shorter TC series, rapid step functions of pressure are generated by a pneumatic pressure pulse calibrator or dead weight tester and readout is by recorder or storage oscilloscope. Manufacturer’s address PCB Piezotronics, Inc. Indian supplier: 3425 Walden Avenue, Structural solutions (India) Pvt. Ltd. Depew, New York 14043-2495. E-mail: [email protected] Web: www.pcb.com 25-12-2010 Im240.docx Page 58 Apex Innovations Eddy Current Dynamometer Introduction The AG Series eddy current dynamometers designed for the testing of engines up to 400kW (536bhp) and may be used with various control systems. The dynamometer is bi-directional. The shaft mounted finger type rotor runs in a dry gap. A closed circuit type cooling system permits for a sump. Dynamometer load measurement is from a strain gauge load cell and speed measurement is from a shaft mounted three hundred sixty PPR rotary encoder. Technical specifications (AG10) Model AG10 Make Saj Test Plant Pvt. Ltd. End flanges both side Cardon shaft model 1260 type A Water inlet 1.6bar Minimum kPa 160 2 Pressure lbf/in 23 Air gap mm 0.77/0.63 Torque Nm 11.5 Hot coil voltage max. 60 Continuous current amps 5.0 Cold resistance ohms 9.8 Speed max. 10000rpm Load 3.5kg Bolt size M12 x 1.75 Weight 130kg Principle of operation 1. The dynamometer unit comprises basically a rotor mounted on a shaft running in bearings which rotates within a casing supported in ball bearing trunnions which form part of the bed plate of the machine. 2. Secured in the casing are two field coils connected in series. When these coils are supplied with a direct current (DC) a magnetic field is created in the casing across the air gap at either side of the rotor. When the rotor turns in this magnetic field, eddy currents are induced creating a breaking effect between the rotor and casing. 25-12-2010 Im240.docx Page 59 Apex Innovations The rotational torque exerted on the casing is measured by a strain gauge load cell incorporated in the restraining linkage between the casing and dynamometer bed plate. 3. To prevent overheating of the dynamometer a water supply pressurized to minimum indicated in specification is connected to a flanged inlet on the bed plate. Water passes from the inlet to the casing via a flexible connection; permitting movement of the casing. Water passes through loss (Grooved) plates in the casing positioned either side of the rotor and absorbs the heat generated. 4. Heated water discharges from the casing through a flexible connection to an outlet flange on the bed plate. Troubleshooting Problem Check Calibration of dynamometer not coming • in accuracy limit Remove the obstruction for the free movement of casing • Calibrate the weights from authorized source. • Maintain constant water flow • Clean & lubricate properly with grease Vibrations to dynamometer • Bearings clean & refit properly • Load cell link tighten properly • Clean & refit trunnion bearings • Dynamometer foundation bolts tighten properly Abnormal noise Loss plate temperature high Bearing temperature high • Arrest engine vibrations • Cardon shaft cover secure properly • Align guard properly • Replace rotor if warped • Replace main bearing • Check correct water flow • De-scale with suitable solution • Clear off water passages • Grease with proper brand • Remove excess grease & avoid over grease • Use specified grease and do not mix two types of grease • 25-12-2010 Clear the drain Im240.docx Page 60 Apex Innovations Dynamometer not rotating • Replace the bearings • Replace shaft & coupling • Replace bearings • Replace rotor / loss plates after checking Water leakages at various locations • Replace casing ‘o’ rings • Loss plates bolts tighten properly • Replace loss plate ‘o’ rings • Casing plugs tighten properly • Replace pipe ‘o’ rings Operation 1. New dynamometers are run in before delivery to ensure that all components run smoothly and grease is evently distributed within the shaft bearings. 2. The dynamometer has been calibrated the power developed by the engine on test may be calculated using the following formula: Power (kW) = Power (hp) = Torque ( Nm) xSpeed ( Radians / sec .) inS .I .units 1000 Torque (lbfft ) xSpeed ( Radians / sec .) in.imperialun its 550 3. The dynamometer will be calibrated in either Imperial or S.I. units or MKS as specified. Power = WN k Where N = Shaft speed in rev/min W = Torque (Indicated on torque indicator) K = Constant dependant on units of power and torque Manufacturer’s address Saj Test Plant Pvt. Ltd. 72-76, Mundhwa, Pune Cantonment, Pune – 411 036. Email:[email protected] 25-12-2010 Im240.docx Page 61 Apex Innovations Load indicator 25-12-2010 Im240.docx Page 62 Apex Innovations 25-12-2010 Im240.docx Page 63 Apex Innovations 25-12-2010 Im240.docx Page 64 Apex Innovations 25-12-2010 Im240.docx Page 65 Apex Innovations 25-12-2010 Im240.docx Page 66 Apex Innovations 25-12-2010 Im240.docx Page 67 Apex Innovations Programming of load indicator (PIC152) If the load indicator shows error in load indication or if the program is disturbed inadvertently it may need reprogramming/recalibration. Follow following steps. Refer Load indicator documents in components’ manual and understand the programming steps and key operations. • Wiring: o The output voltage 24 VDC is available at terminal 17-ve (Black wire) and 18 +ve (Red wire) is converted to 5 VDC and is connected load cell o From load cell white wire is connected to terminal no. 4 as +ve input mV and green wire at terminal no. 5 as -ve input mV. • Calibration: If recalibration is needed fit the load cell on flat platform from bottom side. On top surface of the load cell fix a flat sheet for placing the which will hold the weights up to 50 kg. (Capacity of load cell) • Programming of Level 0 (To enter or exit program mode press both arrow key together for 3 seconds) 1 Up Arrow :- Upward movement 2 Down Arrow :- Downward movement 3 Squre + Up arrow :- Increase value. 4 Squre + Down Arrow :- Decrease value. Press both arrow keys together for 3 seconds. Indicator display shows "ID" and "0". Press Square + Up/ Down key so that the indicator will display "LUL, 0 " Press Up key select "INP" Press Square + Up key together select "AU". Press Up key and set as follows A] RESL (Resolution)----------------------------------- 0.1 B] FtC (Filter time constant)--------------------------1 C] dSCL (Display value scalling point Low-------0.0 D] ISCL (Input value scalling point Low)-----------1.10 (mV input from load cell when the load is 0 kg.) E] dSCH ( Display value scalling point high)-----50.0 (max range of load indicator) F] ISCH ( Input value scalling point High)------------32.00 to 38.00 ( mV input from load cell when the load is 50 kg.) G] RSCL (Reverse scalling)----------------------------- NO H] SPHL (Set point high Limit) ------------------------ 50 I ] SPLL (Set point Low Limit ---------------------------0.0 J] LOCY (Lck code) ---------------------------------------0 K] rst (Reset) -------------------------------------------------No • Programming of Level 3 25-12-2010 Im240.docx Page 68 Apex Innovations Press both arrow keys together for 3 seconds. Indicator displays “ID" and "0". Press Square + Up/ Down key so that the indicator displays "LUL, 3 " Press Up key and set as follows L] MANL (Manual) ------------------------------ Off M] A - LO (Lower Limit) ------------------------0 N] A - HI ( Upper Limit)------------------------- 50 (max.capacity off load cell) Manufacturer’s address Selectron process controls Pvt. Ltd. E-121/120/113, Ansa Industrial Delear: Estate, Saki Vihar Road, Andheri, Mumbai – 400 072. E-mail: [email protected] Web: www.selecindia.com 25-12-2010 Im240.docx Page 69 Apex x Innovatio ons Lo oad cell Introduction Load cell are suitable use for sta atic & dynamic weigh hing, bin/hopper weig ghing, force e measurem ment, scale es and electro-mec e chanical conversion kit. Constructed bod dy of special high alloy s steel. Tech hnical spe ecification ns Make e Sensortron nics Mode el 60001 Type ‘S’ Beam,U Universal acity Capa 0 – 50Kg Moun nting thread d M10 0 x 1.25mm m Full scale s outputt (mV/V) 3.00 Tolerrance on outtput (FSO) +/--0.25% Zero balance (FS SO) +/--0.1mV/V Non-linearity (FS SO) <+/-0.025% Hyste eresis (FSO)) <+/-0.020% Non-repeatability y <+/-0.010% Creep p (FSO) in 30 3 min <+/-0.020% Operrating tempe erature rang ge -20 00C to +700C Rated d excitation 10V V AC/DC Maxim mum excitation 15V V AC/DC Bridg ge resistance e 350 0 Ohms (Nominal) Insulation resista ance >10 000 Meg ohm @ 50VDC C 0 Span n / C (of loa ad) +/--0.001% Zero / 0C (of FSO O) +/--0.002% Comb bined error (FSO) <+/-0.025% Safe overload (F FSO) 150 0% Ultim mate overloa ad (FSO) 300 0% Prote ection class IP 6 67 Overall dimensio ons 51 L x 20 W x 76 H mm Weight 380 0 gm Man nufacturerr’s address Sensortronics Sa anmar Ltd. A, Old Maha abalipuram Road, 38/2A Perun ngudi, Chen nnai – 600 096. 0 E-ma ail: KBS@SA ANMARGROU UP.com 25 12 2 2010 Im2 240 doc Page 70 Apex Innovations Air flow transmitter 25-12-2010 Im240.docx Page 71 Apex Innovations 25-12-2010 Im240.docx Page 72 Apex Innovations Manufacturer’s address WIKA Instruments Ltd. Wika Instruments India Pvt. Ltd. Garmany. Plot No. 40, GatNo. 94+100, high Cliff Ind. Web: www.wika.de Estate, Village Kesnand, Pune 412207 25-12-2010 Im240.docx Page 73 Apex Innovations Differential Pressure Transmitter Introduction The model EJA110A pressure transmitter measures the flow rates and the pressure of the liquids, gases, and steam, and also liquid levels. Technical specifications Model EJA110A-DMS5A-92NN Make Yokogawa Output signal 4 – 20mA DC with digital communication (Linear) Measurement span 1 to 100kPa (100 to 10000mmH2O) Calibration range 0 – 200, 0 – 500 mmH2O Wetted parts material Body – SCS14A, Capsule – SUS316L Process connections without process connector (1/4BSP body connection) Bolts and nuts material SCM 435 Installation Horizontal impulse piping left side high pressure Electrical connection 1/2NPT female Cover ‘O’ rings Buna-N Supply 10 to 24VDC Process temperature limit -40 to 120 0C Housing Weather proof Weight 3.9Kg Manufacturer’s address Yokogawa Electrical Corporation Indian supplier: 2-9-32, Nakacho, Yokogawa India Ltd. Musashino-shi, 40/4 Lavelle Road, Tokyo, 180-8750, Japan. Bangalore – 560 001. 25-12-2010 Im240.docx Page 74 Apex Innovations Warranty This product is warranted for a period of 12 months from the date of supply against manufacturing defects. You shall inform us in writing any defect in the system noticed during the warranty period. On receipt of your written notice, Apex at its option either repairs or replaces the product if proved to be defective as stated above. You shall not return any part of the system to us before receiving our confirmation to this effect. The foregoing warranty shall not apply to defects resulting from: Buyer/ User shall not have subjected the system to unauthorized alterations/ additions/ modifications. Unauthorized use of external software/ interfacing. Unauthorized maintenance by third party not authorized by Apex. Improper site utilities and/or maintenance. We do not take any responsibility for accidental injuries caused while working with the set up. Apex Innovations Pvt. Ltd. E9/1, MIDC, Kupwad, Sangli-416436 (Maharashtra) India Telefax:0233-2644098, 2644398 Email: [email protected] Web: www.apexinnovations.co.in 25-12-2010 Im240.docx Page 75 MECHANIC LAB SIMPLE VIBRATION TEST 1. Fundamentals of Mechanical Vibration In this experiment, you will learn about the fundamentals of the mechanical vibrations. The mechanical vibration can be defined as the motion of the bodies which is displaced from its equilibrium position. If the system is in equilibrium position and if you apply a force by changing its position, the system tries to come its equilibrium position by repetitive motions by translation or by rotation. This behaviour of the bodies is defined as mechanical vibration. In general, the vibration systems consist of three elements : 1- Mass of the system (m) 2- Spring constant of system(k) 3- Damping coefficient of the system(C) Figure 1. Simple spring mass system In Figure 1, there is mass(m) and spring whose spring constant is k, are hanged. The system is in equilibrium position. The movement direction is taken as positive(+) in downward direction and negative in upward direction(-). When you pull the mass downward and release it, the mass goes repetitively upward and downward. At the end of the movements (when its energy is consumed as kinetic energy), it stops its original(equilibrium) position. The graphics of this mechanical movements is shown in the figure 1. The graphics shows the mass, “m”, oscillates between the upper and lower amplitude “l”. This type of motion is called harmonic motion. The harmonic motion (periodic motion or oscillation) can 1 be described as the restoring force in the system is against the displacement taken during motion. Figure 2. Graphics of simple vibration (ideal system and conditions) The mathematical model of spring-mass system : d 2s ds m 2  C  ks  F (t ) dt dt Eq.1 In Equation 1 : m= mass of the system(kg) C=damping coefficient of the system(kg/s) k=spring constant(N/mm) s=the displacement (mm) F(t)= time dependent Force (N) 2.The Definitions used in the Vibration Systems Frequency (f) : The amount of cycles that a system makes in a unit time. It is demonstrated by f and very important in vibration phenomena. It is dependent on the spring stiffness (k) and mass of the system(m). Its unit is 1/second or Hertz(Hz). Natural frequency (Wn) : Natural frequency is the frequency at which the system vibrates free vibration conditions. Namely, there is no any external forced on the system. It is shown by Wn and its unit is Hz. In the forced vibration condition, when the frequency of the 2 force is equal to the natural frequency of the system, the amplitude of the vibration equals goes to the infinity. This event is called as Resonance. Period (T) : The period is the time passes for one cycle of the motion. It is demonstrated by T and its unit is seconds(s). Damping Coefficient(C) and Damping Ratio(r) : This definitions are related to the damping. The damping means the resistance to the vibration. When the damping coefficient gets higher, the vibration amplitude and duration gets lower. The damping coefficient is demonstrated by C and its unit is kg/s , the damping ratio is shown by r and it is unitless. 3.Types of Vibration The types of vibration mainly divided into two main categories as Free Vibration and Forced Vibration. The Free Vibration is the vibration which there is no any force, F(t), applied on the mass, namely F(t)=0. The Forced Vibration, in contrast, the vibration which a force, F(t) is applied on the mass. In this experimental setup we will see the Free Vibration only since we do not apply any F(t) during motion. At the same time, these vibration types can be subdivided into two categories as Undamped Vibration and Damped Vibration. If there is a resisting force against vibration, the system is called Damped Vibration, if not the system is called Undamped Vibration. 3.1. Free Undamped Vibration (F(t)=0 & C=0) 3 This system only includes mass(m) and spring stiffness(k). There is no damper in the system. The mass is pulled and released. The motion of the system will be observed and the spring stiffness(k), frequency(f) and period(T) of the system will be calculated by both theoretical and experimental methods. When F(t)=0 and C=0 , the equation becomes d 2s m* 2  k *s  0 dt Eq.2 d 2s k k 2  * s  0 and the natural frequency W  n m dt 2 m Wn  k (Natural Frequency Equation) m s(t )  s0 *CosWnt (The Amplitude Function) T Figure 3. The Free Undamped Vibration Graph an period prediction (ideal condition) T 1 2 and T  (sec)  f Wn 3.2. Free Damped Vibration (F(t)=0 & C≠0) 4 f  1 (Hz) T In this system, a damper is included. A damper is a resistive environment for reducing vibration. In our experimental setup, a piston which has holes on it is moved in an oil cap. While the piston moves together with mass(m), the mass losses its energy in every cycle and the vibration is absorbed by this way. Namely, damping is produced by processes that dissipate the energy stored in the oscillation. The aim in this experiment is to obtain the damping coefficient(C) and damping ratio of the system(r). Figure 4. Basic Free damped system The motion equation for this system is : d 2s ds m* 2  C *  k *s  0 dt dt d 2 s C ds k  *  *s  0 dt 2 m dt m Or we can write he equation : d 2s ds  2 *Wn *  Wn2 * s  0 2 dt dt where r  5 C 2 * Wn * m Eq.3 Figure 5. Free Damped Vibration Types In Figure 5, The free damped vibration systems are shown. In the figure, actually there are four category. But first one is Undamped vibration showing that r=0. In free damped vibration, there are 3 situation as Underdamped(r<1) the roots are complex roots, Critically damped(r=1) the roots are equal and opposite sign and Overdamped(r>1) there are two distinct real roots. It depends on the solution of the differential equation of the motion. (Eq.3). The root of this equation defines the types of the equation. a. If r<1 It is called Underdamped free vibration. The equation of motion becomes s(t )  e r*Wn *t *( A *CosWd * t  B *Sin Wd * t ) The damping ratio(r) can be calculated from: r  The damped period : Td  1 s * ln n 2 sn1 2 Wn * 1  r 2 The damped natural frequency(Wd) : Wd  Wn * 1  r 2 b. If r=1 it is called Critically damped free vibration. The motion equation s(t )  ( A  Bt ) * e r*Wn *t c. If r>1 it is called Overdamped free vibration. The motion equation becomes 6 s(t )  A * e(  r  r 2 1)*Wn *t  B * e(  r  r 2 1)*Wn *t  s(t) is the displacement(amplitude) of the spring changing with time Experimental Setup 2 1 7 4 3 Figure 6. Experimental Setup & Equipments (1 Spring, 2 Mass attached to spring, 3 Damper(oil pan), 4 Whole experimental setup). The Graphs from Experiment Figure 7. Calculation of spring stiffness, k 8 Figure 8. Calculation of period(T) and frequency(f)-Free Undamped Vibration Figure 9. Calculation of damping ratio(r) -Underdamped Vibration Figure 10. Calculation of damping coefficient(C)-Overdamped Vibration Conclusions 9 In this experiment, the fundamentals of mechanical vibration are given. Some experiments are made and parameters of the vibration(f, T, C, r) is calculated theoretically and experimentally. The student will learn more about other vibration types and improve himself/herself. The report requirements are as following questions : Questions 1- Find the spring constant(k) of the system. 2- Determine the frequency(f) and period(T) of the undamped system under different masses. 3- Find the damping coefficient(C) and damping ratio(r) of the underdamped system. 4- Find the damping coefficient(C) of the overdamped system. 5- By using MS Excel draw the graphics according to s(t) function in free undamped system with changing the mass(m) and spring constant(k) with same amplitude. 6- Draw the graphics of mass(m)-natural frequency(Wn) & spring constant(k)-natural frequency(Wn) to show the effects of mass and spring constant on natural frequency. 7- Explain the Resonance event and give examples about it. 10