BHARATHIDASAN ENGINEERING COLLEGE NATTRAMPALLI 635 854 DEPARTMENT OF MECHANICAL ENGINEERING LABORATORY MANUAL ME6412 THERMAL ENGINEERING LABORATORY - I YEAR / SEMESTER : II / IV DEPARTMENT : Mechanical REGULATION : 2013 Name Reg. No Branch Year & Semester : : : : PREPARED BY Mr.N.RAJESH.M.E., AP/MECHANICAL 1
TABLE OF CONTENTS Ex.No Date Name of the Experiment Mark Signature 1 2 3 4 PORT TIMING DIAGRAM OF TWO STROKE PETROL ENGINE VALVE TIMING DIAGRAM OF FOUR STROKE DIESEL ENGINE REDWOOD VISCOMETER DETERMINATION OF FLASH POINT AND FIRE POINT OF VARIOUS FUELS / LUBRICANTS 5 6 PERFORMANCE TEST ON FOUR STROKE DIESEL ENGINE BY MECHANICAL LOAD PERFORMANCE TEST ON FOUR STROKE DIESEL ENGINE BY ELECTRICAL LOAD 7 MORSE TEST ON MULTI CYLINDER PETROL ENGINE 8 HEAT BALANCE TEST ON FOUR STROKE DIESEL ENGINE 9 RETARDATION TEST ON A DIESEL ENGINE 10 STUDY OF STEAM GENERATORS & STEAM TURBINE 11 PERFORMANCE AND ENERGY BALANCE TEST ON A STEAM GENERATOR 2
Ex.NO: Aim: 1. PORT TIMING DIAGRAM OF TWO STROKE PETROL ENGINE Date: To draw the port timing diagram of given two stroke cycle petrol engine. Apparatus Required: 1. Two stroke petrol engine 2. Measuring tape 3. Chalk Theory and Description: In the case of two stroke cycle engines the inlet and exhaust valves are not present. Instead, the slots are cut on the cylinder itself at different elevation and they are called ports. There are three ports are present in the two stroke cycle engine. 1. Inlet port 2. Transfer port 3. Exhaust port The diagram which shows the position of crank at which the above ports are open and close are called as port timing diagram. The extreme position of the piston at the bottom of the cylinder is called Bottom Dead centre [BDC]. The extreme position of the piston at the top of the cylinder is called TOP dead centre [TDC] In two stroke petrol engine the inlet port open when the piston moves from BDC to TDC and is closed when the piston moves from TDC to BDC. The transfer port is opened when the piston is moved from TDC to BDC and the fuel enters into the cylinder through this transport from the crank case of the engine. The transfer port is closed when piston moves from BDC to TDC. The transfer port opening and closing are measured with respect to the BDC. The exhaust port is opened, when the piston moves from TDC to BDC and is closed when piston moves from BDC to TDC. The exhaust port opening and closing are measured with respect to the BD 3
Tabulation: Sl. No. Event Position of crank w.r to TDC or BDC Distance in cm Angle in Degree 1 IPO Before TDC 2 IPC After TDC 3 EPO Before BDC 4 EPC After BDC 5 TPO Before BDC 6 TPC After BDC Port Timing Diagram: 4
Formula: Procedure: Required angle = Distance x 360 Circumference of the flywheel Where, Distance = Distance of the valve opening or closing position marked on flywheel with respect to their dead centre 1. Remove the ports cover and identify the three ports. 2. Mark the TDC and BDC position of the fly wheel. To mark this position follow the Same procedure as followed in valve timing diagram. 3. Rotate the flywheel s l o w l y in usual direction (usually clockwise) a n d observe the movement of the piston 4. When the piston moves from BDC to TDC observe when the bottom edge of the piston. Just uncover the bottom end of the inlet port. This is the inlet port opening (IPO) condition, make the mark on the flywheel and measure the distance from TDC 5. When piston moves from TDC to BDC observe when the bottom edge of the piston Completely covers the inlet port. This is the inlet port closing (IPC) condition. Make the mark on the flywheel and measure the distance from TDC. 6. When the piston moves from TDC to BDC, observe, when the top edge of the piston just uncover the exhaust port. This is the exhaust port opening [EPO] condition. Make the mark on the flywheel and measure the distance from BDC. 7. When the piston moves from BDC to TDC, observe, when the piston completely cover the exhaust port. This is the exhaust port closing condition [EPC]. Make the mark on the flywheel and measure the distance from BDC. 8. When the piston moves from TDC to BDC observe, when the top edge of the piston just uncover the transfer port. This is the transfer port opening [TPO] condition. Make the mark on the flywheel and measure the distance from BDC 9. When the piston moves from BDC to TDC, observe, when the piston completely covers the transfer port. This is the transfer port closing [TPC] condition. Make the mark on the flywheel and measure the distance from BDC. 5
Result: Thus the port time for the given two stroke engine is found out and the port timing diagram is drawn. Inlet port opens = Inlet port closes = Transfer port opens = Transfer port closes = Exhaust Port opens = Exhaust port closes = 6
Ex.NO: 2. VALVE TIMING DIAGRAM OF FOUR STROKE DIESEL ENGINE Date: Aim: To draw the valve timing diagram of the given four stroke cycle diesel engine. Apparatus Required: 1. Four stroke cycle diesel engine 2. Measuring tape 3. Chalk 4. Piece of paper Theory and Description: The diagram which shows the position of crank of four stroke cycle engine at the beginning and at the end of suction, compression, expansion, and exhaust of the engine are called as Valve Timing Diagram. The extreme position of the bottom of the cylinder is called Bottom Dead Centre [BDC].IN the case of horizontal engine, this is known as Outer Dead Centre [ODC]. The position of the piston at the top of the cylinder is called Top Dead Centre [TDC].In case of horizontal engine this is known as Inner Dead Centre [TDC].In case of horizontal engine this is known as inner dead centre [IDC] Inlet Valve opening and closing: In an actual engine, the inlet valve begins to open 5 C to 20 C before the piston reaches the TDC during the end of exhaust stroke. This is necessary to ensure that the valve will be fully open when the piston reaches the TDC. If the inlet valve is allowed to close at BDC, the cylinder would receive less amount of air than its capacity and the pressure at the end of suction will be below the atmospheric pressure. To avoid this the inlet valve is kept open for 25 to 40 after BDC. Exhaust valve opening and closing Complete clearing of the burned gases from the cylinder is necessary to take in more air into the cylinder. To achieve this the exhaust valve is opens at 35 to 45 before BDC and closes at 10 to 20 after the TCC. It is clear from the diagram, for certain period both inlet valve and exhaust valve remains in open condition. The crank angles for which the both Valves are open are called as overlapping period. This overlapping is more than the petrol engine. Fuel valve opening and closing: The fuel valve opens at 10 to 15 before TDC and closes at 15 to 20 after TDC. This is because better evaporation and mixing fuel. 7
Tabulation: Sl. No. Event Position of crank w.r to TDC or BDC Distance in cm Angle in Degree IVO Before TDC IVC After BDC EVO Before BDC EVC After TDC Valve Timing Diagram: 8
Formula: Procedure: Required angle = Distance x 360 Circumference of the flywheel Where, Distance = Distance of the valve opening or closing position marked on flywheel with respect to their dead centre 1. Remove the cylinder head cover and identify the inlet valve, exhaust valve and piston of particular cylinder. 2. Mark the BDC and TDC position of flywheel This is done by rotating the crank in usual direction of rotation and observe the position of the fly wheel, when the piston is moving downwards at which the piston begins to move in opposite direction. i.e from down to upward direction. Make the mark on the flywheel with reference to fixed point on the body of the engine. That point is the BDC for that cylinder.measure the circumference. That point is TDC and is diametrically opposite to the BDC. 3. Insert the paper in the tappet clearance of both inlet and exhaust valves 4. Slowly rotate the crank until the paper in the tappet clearance of inlet valve is gripped.make the mark on fly wheel against fixed reference. This position represent the inlet valve open (IVO). Measure the distance from TDC and tabulate the distance. 5. Rotate the crank further, till the paper is just free to move. Make the marking on the flywheel against the fixed reference. This position represent the inlet valve close (IVC). Measure the distance from BDC and tabulate the distance. 6. Rotate the crank further, till the paper in the tappet clearance of exhaust valve is gripped. Make the marking on the flywheel against fixed reference. This position represents the exhaust valve open (EVO). Measure the distance from BDC and tabulate. 7. Then convert the measured distances into angle in degrees Result: Thus the valve timing for the given four stroke engine is found out and is drawn. Inlet valve opens = Inlet valve closes = Exhaust valve opens = Exhaust valve closes = 9
3. REDWOOD VISCOMETER Ex.NO: Date: Aim: To determine the kinematic viscosity and absolute viscosity of the given lubricating oil at different temperatures using Redwood Viscometer Apparatus required: 1) Redwood Viscometer 2) Thermometer 0-100 c 3) Stop watch 4) 50 ml standard narrow necked 5) Flask Given Sample of oil Description: The redwood viscometer consist of vertical cylindrical oil cup with an orifice in the centre of its base. The orifice can be closed by a ball. A hook pointing upward serve as a guide mark for filling the oil. The cylindrical cup is surrounded by the water bath. The water bath maintain the temperature of the oil to be tested at constant temperature. The oil is heated by heating the water bath by means of an immersed electric heater in the water bath, the provision is made for stirring the water, to maintain the uniform temperature in the water bath and to place the thermometer ti record the temperature of oil and water bath. The cylinder is 47.625mm in diameter and 88.90mm deep. The orifice is 1.70mm in diameter and 12mm in length, this viscometer is used to determine the kinematic viscosity of the oil. From the kinematic viscosity the dynamic viscosity is determined. Theory and Definition: Viscosity is the property of fluid. It is defined as The internal resistance offered by the fluid to the movement of one layer of fluid over an adjacent layer. It is due to the Cohesion between the molecules of the fluid. The fluid which obey the Newton law of Viscosity are called as Newtonian fluid. The dynamic viscosity of fluid is defined as the shear required to produce unit rate of angular deformation. 10
Tabulation: S.no Temperature of oil Time taken for collecting 50cc oil in flask Kinematic viscosity in m 2 /s Dynamic viscosity in NS/m 2 1 2 3 4 5 11
Formula used: 1. Density (ρ) = ρ15 [1-α (T-15)] kg/m 3 Where, ρ15 = Density of the given oil = α = 0.00036 T =Temperature of oil 2. Kinematic Viscosity (ν ) = At B/t x 10-6 m 2 /s t = t i m e t a k e n t o c o l l e c t 50ml i n s e c o n d 3. Dynamic Viscosity (μ) μ = ρ x ν in NS/m 2 Procedure: (1) Clean the cylindrical oil cup and ensure the orifice tube is free from dirt. (2) Close the orifice with ball valve. (3) Place the 50 ml flask below the opening of the Orifice. (4) Fill the oil in the cylindrical oil cup upto the mark in the cup. (5) Fill the water in the water bath. (6) Insert the thermometers in their respective places to measure the oil and water bath temperatures. (7) Heat the by heating the water bath, Stirred the water bath and maintain the uniform temperature. (8) At particular temperature lift the bal valve and collect the oil in the 50 ml flask and note the time taken in seconds for the collecting 50 ml of oil. A stop watch is used measure the time taken. This time is called Redwood seconds. (9) Increase the temperature and repeat the procedure 8 and note down the Redwood Seconds for different temperatures. Graph: The following graph has to be drawn (1)Temperature Vs Kinematic Viscosity (2)Temperature Vs Dynamic Viscosity Result: The kinematic and dynamic viscosity of given oil at different temperatures were determined and graphs were drawn. 12
4. DETERMINATION OF FLASH POINT AND FIRE POINT OF VARIOUS FUELS / LUBRICANTS. Ex.NO: Date: Aim: To determine the flash and power point temperatures of the given sample of Lubricating oil using Cleveland open cup apparatus. Apparatus Required: 1. Cleveland open cup apparatus 2. Thermometer 3. Splinter sticks 4. Sample of oil Theory and Definition: The flash point of the lubricating oil is defined as the lowest temperature at which it forms vapours and produces combustible mixture with air. The higher flash point temperature is always desirable for any lubricating oil. If the oil has the lower value of f l a s h p o i n t temperatures, it will burn easily and forms the carbon deposits on the moving parts. The minimum flash temperature of the oil used in IC engines varies from 200 C to 250 C. When the oil is tested using the open cup apparatus, the temperature is slightly more than the above temperatures. The flash and fire point temperatures may differs by 20 C to 60 C when it is tested by open cup apparatus. However, a greater difference may be obtained if some additives are mixed with oil. The flash and fire power point temperatures depends upon the volatility of the oil. Description: The Cleveland open cup apparatus consists of a cylindrical cup of standard size. It is held in position in the metallic holder which is placed on a wire gauge. It is heated by means of an electric heater housed inside the metallic holder. A provision is made on the top of the cup to hold the thermometer. A standing filling mark is done on the inner side of the cup and the sample of oil is filled up to the mark. This apparatus will give more accurate results than the pensky martens closed cup apparatus. 13
Tabulation: S. No. Name of the oil sample Temperature ( 0 C) Observations 1 2 3 4 5 6 Cleaveland open cup Apparatus 14
Procedure: 1. Clean the cup and fill it with the given sample of oil up to the filling mark. 2. Insert the thermometer in the holder. Make sure that the thermometer should not touch the metallic cup. 3. Heat the oil by the means of electric heater so that the sample of oil gives out vapour at the rate of 10 C per minute. 4. When the oil gives out vapour, introduce the test flame above the oil, without touching the surface of the oil and watch for flash with flickering sound. 5. Introducing the test flame should not continued at regular intervals until the flash is observed with peak flickering sound. The temperature corresponding to this flickering sound is noticed and it is the flash point temperature of the given sample of oil. 6. Continue the process of heating and introducing the test flame until the oil will begins to burn continuously and observe the temperature. This is the fire pint temperature of the given sample of oil. 7. Repeat the test twice or thrice with fresh sample of oil and observe the results. 8. The observations are tabulated. Result: The flash and fire point temperatures of the given sample of oil were determined using Cleveland open cup apparatus. 1) The flash point temperature of the given sample of oil is C 2) The fire point temperature is of the given sample of oil is C 15
5. PERFORMANCE TEST ON FOUR STROKE DIESEL ENGINE BY MECHANICAL LOAD Ex.NO: Date: Aim: To conduct Performance test on a Single cylinder 4-stroke diesel engine by mechanical loading with different loads at constant speed and draw the characteristics curve. Apparatus Required: 1. Diesel engine with loading arrangement 2. Thread and scale (or) measuring tape 3. Stop watch 4. Tachometer Procedure: 1. Calculate maximum load to be applied for a selected engine 2. Check the fuel supply, water circulation in the water system and lubricating oil in the oil sump. 3. Ensure no load condition 4. The engine is started and allowed to run on idle speed for a few minutes. 5. Gradually the engine is loaded by mechanical brake method and the speed is maintained constant. 6. Make sure the cooling water is supplied to the brake drum. 7. Load the engine in steps of 0%, 25%, 50%, 75% & 100% of maximum load to be applied. 8. Note the corresponding readings of spring balance, fuel consumption, manometer reading. 9. After taking the readings, unload the engine, allow it to run for few minutes and then stop the engine. 16
Tabulation: 17
Formula: 1. Break power: BP = 2 π N T KW 60 x 1000 2. Total Fuel consumption TFC =Sp.Gravity x Volume of fuel consumed (cc) x 3 6 0 0 kg / hr. t x 1000 Sp.Gravity of diesel = 0.83 Vol.of fuel consumed = 10 ml Time for 10cc of fuel consumption= t 3. Specific Fuel Consumption: SFC = TFC B.P Kg / KW hr 4. Indicated Power I.P = B.P + F.P 5. Mechanical Efficiency: Where F. P = Frictional Power from William s line diagram mech = B.P x 100 I.P 6. Brake thermal efficiency or overall efficiency: It is defined as the ratio of brake power to heat supplied by the combustion of fuel. B.T or overall = B.P x 100 TFC X CV Calorific value of the diesel 44631.96 KJ / Kg 7. Indicated thermal efficiency or Thermal efficiency I.T = IP x 3600 x 100 TFC x C.V 18
Graph: The following graphs has to be drawn 1. B.P Vs SFC 2. B.P Vs B.T 3. B.P Vs I.T Result: The performance test is conducted for a Single cylinder four stroke diesel engine by mechanical loading with different loads and the characteristics graphs are draw. 19
6. PERFORMANCE TEST ON FOUR STROKE DIESEL ENGINE BY ELECTRICAL LOAD Ex.NO: Date: Aim: To conduct Performance test on a Single cylinder 4-stroke diesel engine by Electrical loading with different loads at constant speed and draw the characteristics curve. Apparatus required: Procedure: Tachometer Stopwatch Thermometer Measuring setup 1. Calculate maximum load to be applied for a selected engine 2. Check the fuel supply, water circulation in the water system and lubricating oil in the oil sump. 3. Ensure no load condition 4. The engine is started and allowed to run on idle speed for a few minutes. 5. Gradually the engine is loaded by mechanical brake method and the speed is maintained constant. 6. Make sure the cooling water is supplied to the brake drum. 7. Load the engine in steps of 0%, 25%, 50%, 75% & 100% of maximum load to be applied. 8. Note the corresponding readings of voltmeter, ammeter, Fuel consumption fuel consumption, manometer reading. 9. After taking the readings, unload the engine, allow it to run for few minutes and then stop the engine. 20
Observation: Specific gravity of the fuel = Calorific value of the fuel = Efficiency of alternator( a) = Input voltage (Vi) = Maximum load to be applied Amax=BP x a x 1000 Am/s Vi Where, BP=Engine standard BP mention in engine Name plate BP= HP x 736 Watts Formula used: 1. Brake Power B.P = V X I ɳ x 1000 V=Voltmeter reading in volts KW I=Ammeter reading in amps ɳ =Generator efficiency= 0.85 2. Total Fuel consumption TFC =Sp.Gravity x Volume of fuel consumed (cc) x 3 6 0 0 kg / hr. t x 1000 Sp.Gravity of diesel = 0.83 Vol.of fuel consumed = 10 ml Time for 10cc of fuel consumption= t 3. Specific Fuel Consumption: SFC = TFC B.P Kg / KW hr 21
4. Indicated Power I.P = B.P + F.P Where F. P = Frictional Power from William s line graphical method 5. Mechanical Efficiency: mech = B.P x 100 I.P 6. Brake thermal efficiency or overall efficiency: It is defined as the ratio of brake power to heat supplied by the combustion of fuel. B.T or overall = B.P x 100 TFC X CV Calorific value of the diesel 44631.96 KJ / Kg 7. Indicated thermal efficiency or Thermal efficiency I.T = IP x 3600 x 100 TFC x C.V 22
Tabulation: 23
Graph: The following graphs has to be drawn 1. B.P Vs SFC 2. B.P Vs B.T 3. B.P Vs I.T Result: The performance test is conducted for a Single cylinder four stroke diesel engine by Electrical loading with different loads and the characteristics graphs are draw. 24
7. MORSE TEST ON MULTI CYLINDER PETROL ENGINE Ex.NO: Date: Aim: To conduct morse test on given multi cylinder petrol engine in order to determine the indicated power developed in the each cylinder of the engine and to determine the mechanical efficiency. Apparatus Required: 1. Multi cylinder petrol engine with ignition cut off arrangement 2. Loading arrangements 3. Tachometer Theory and Description: For slow speed engine the indicated power is directly calculated from the indicator diagram. But in modern high speed engines, it is difficult to obtain accurate indicator diagram due to inertia forces, and therefore, this method cannot be applied. In such cases the morse test can be used to measure the indicated power and mechanical efficiency of multi cylinder engines. The engines test is carried out as follows. The engine is run at maximum load at certain speed. The B.P is then measured when all cylinders are working. Then one cylinder is made in operative by cutting off the ignition to that cylinder. As a result of this the speed of the engine will decrease. Therefore, the load on the engine is reduced so that the engine speed is restored to its initial value. The assumption made on the test is that frictional power is depends on the speed and not upon the load on the engine. Procedure: 1. Check the engine for fuel availability, lubricant and cooling water connections. 2 Release the load completely on the engine and start the engine in no load conditions and allow the engine to run for few minutes to attain the rated speed. 3. Apply the load and increase the load upto maximum load. (All four cylinders should be in working). Now note the load on the engine and speed of the engine say the speed is N rpm 4. Cut-off the ignition of first cylinder, now the speed of engine decreased. Reduce the load on the engine and bring the speed of the engine to N rpm. Now note the load on the engine. 5.Bring the all four cylinders are in working conditions and cut off the 2 nd, 3 rd and 4 th cylinder in turn and adjust the load to maintain same N rpm and note the load. 25
Observation and Tabulation: (1) Brake power B.P =... KW (2) Rated Speed N =...Rpm (3) Type of loading : =... (4) Radius of brake drum : R =... m (5) Radius of Rope r = =... m (6) Number of cylinders = 4 S No Conditions Loading Speed BP KW W1 kg W2 W1 W2 Net load Rpm kg kg W in N 1 All cylinders are working 2 First cylinder was cut off and remaining are in working 3 Second cylinder was cut off and remaining are in working 4 Third cylinder was cut off and remaining are in working 5 Fourth cylinder was cut off and remaining are in working Note: The speed should be same for all readings 26
Formula: Break power: (BP) The useful power available at the crank shaft of the engine is called brake power of the engine. The brake power of the engine are determined by 1. Rope brake dynamometer. T = WRe W = net load Re = effective radius of the brake drum 2. Prony brake dynamometer T = WL W L = Load = Distance at which the load is applied 3. Hydraulic dynamometer B.P = WN C W = Load N = Speed in RPM C = Dynamometer constant 4. Electrical dynamometer Indicated power: (IP) The power actually developed inside the engine cylinder due to the combustion of the fuel are called indicated power. Frictional power (FP): IP = FP + BP; FP = Frictional power The power loss due to friction between the moving parts are called as frictional power. Mechanical efficiency: ( mech ) It is defined as the ratio of Brake power to indicated power. mech=b.p x 100 I.P 27
From the name plate details, determine the maximum load that can be given to the Engine For example: B.P = 12.5 kw, N = 2000 rpm B.P = 2πNT 60 x 1000 T = 60 x 1000 x 12.5 = 59.68 N-m 2 π x 2000 T = W.Re Say Re = 0.4m... W = T = 59.68 = 149.2N Re 0.4 ~ 150 N Result: Morse test was conducted on given petrol engine and indicated power developed in each cylinder are determined and mechanical efficiency are also determined 28
8. HEAT BALANCE TEST ON FOUR STROKE DIESEL ENGINE Ex.NO: Aim: Date: To conduct the test on the given IC engine and to prepare the heat balance sheet. Apparatus Required: 4. Given IC engine with loading arrangement 5. measuring tape or Thread and scale 6. Tachometer 7. Stop watch 8. Bucket 9. Spring balance 10. Thermometer (3 Nos) Theory and Description: A heat balance sheet is an account of heat supplied and heat utilised in various ways in the system. Necessary information concerning the performance of the engine is obtained from the heat balance sheet. The heat balance sheet is generally done on second basis or minute basis or hour basis. The engine should equipped with suitable loading arrangement to measure the brake power of the engine. Provisions are also made to measure the amount of air intake. Amount of fuel consumed, temperature of cooling water at inlet and outlet of the engine amount of cooling water circulated and temperature of exhaust gases. The heat supplied to the engine is only in the form of fuel heat and is equal to. Qs = mf x C.V Where, mf = mass of fuel used in kg/min C.V = Calorific value of fuel in KJ /kg The various way in which the heat is utilized are 1. Heat equivalent to brake power of the engine. 2. Heat carried away by the cooling water 3. Heat carried away by the exhaust gases 4. Unaccounted heat losses. Procedure: 1. From the name plate details, calculate the maximum load that can be applied on the given engine. 2. Check the engine for fuel availability, lubricant and cooling water connection 3. Release the load on engine completely and start the engine with no load condition. Allow the engine to run for few minute to attain the rated speed 4. Adjust the cooling water flow and maintain steady flow of water. 5. Apply the load, from no load to required load slowly. At required load slowly. At required load note the following. 29
i) Load on the engine ii) Speed of the engine in Rpm iii) Time taken for 10 cc of fuel consumption iv) Manometer readings v) Temperature of cooling water at engine inlet and engine outlet in C vi) Time taken for collection of 5 lit or 10 lit of cooling water vii) Room temperature and temperature of exhaust gases Tabulation: Sl.No Load(W) in Kg Time for 10 cc fuel consumption Temperature( C) T1 T2 T3 T4 T5 T.F.C Kg/hr Heat Balance Sheet: Sl.No Load Heat Input B.P P water P exhaust P unacc input Kg KW KW % KW % KW % KW % 30
Formulae: 1. Total Fuel consumption TFC = ( Kg/hr) Where, q = Fuel consumption (10cc) t = Time taken for 10cc of fuel consumption (sec) ρ = Density of diesel =0.83 kg/m 3 2. Specific Fuel consumption SFC SFC = TFC/BP (Kg/Kwhr) 3. Heat input, HI = TFC x calorific value / 3600 ( Kw) Where CV= 43000 Kj/Kg 4. Brake power, BP = Where, T = Torque = RS N-m R= Torque arm length = 0.3 m S = spring balance reading (kg) 5. Heat carried by cooling water, Q w = m w C pw (T w2 -T w1 ) kw Where, T w1 = Inlet temperature of engine cooling water ( 0 C) T w2 = Outlet temperature of engine cooling water ( 0 C) C pw = Specific heat of water = 4.187 kj/kg 0 K m w = Mass flow rate of cooling water = kg/sec t w = Time taken for flow of 1 litres of water 6. Heat carried by exhaust gas Qg = m g C pg (T ag -T a ) kw Where, T ag = Exhaust gas temperature ( 0 C) T a = Atmospheric temperature ( 0 C) C pg = Specific heat of exhaust gas = 1.1 kj/kg 0 K m g = Mass flow rate of exhaust gas = TFC+m a m a = Mass flow rate of air = C d A ρ a (kg/sec) Cd = Co-efficient of discharge of orifice meter = 0.62 A = Area of orifice = m 2 d = Diameter of orifice = 20mm H a = Head of air column = H w H w = Head of water column (m) ρ w = Density of water = 1000kg/m 3 ρ a = Density of air = kg/m 3 p a = Atmospheric pressure = 1.01325 10 5 N/m 2 R = Characteristic gas constant of air = 287 J/kg K m 31
7. Percentage of brake power, %BP = 8. Percentage of heat carried by cooling water, %Q w = 9. Percentage of heat carried by exhaust gas, %Q g = 10. Percentage of unaccounted loss = 100-(%BP + %Q w + %Q g ) Result: The test was conducted on the given IC engine and the heat balance sheet was prepared for the particular load. 32
9. RETARDATION TEST ON A DIESEL ENGINE Ex.NO: Date: Aim: To conduct a retardation test on engine and determine the frictional power loss and hence determine the mechanical efficiency.. Apparatus required: 1. Stop watch 2. Tachometer Technical details of the engine: Four stroke diesel water-cooled brake drum loading: 1. Brea k power. : 2. Lubrication. oil: 3. Rated speed. : Procedure: 1. Start the engine by hand cracking with the decompression lever pressing down the exhaust value. 2. Tack out the hand crank release the decompression lever to run at no load for about 5-10 mines to warm up and attain steady state condition at rated speed. 3. Adjust the rate of cooling water flow. 4. By pulling the control rod cut off the diesel supply to the engine and simultaneously start the stop watch. 5. Record the time for crankshaft speed to reduce 560, 460, 360, rpm by running the stopwatch. Model calculation: Effective radius, Re = Brake drum radius + Radius of rope 1. Brake torque B.T = W x 9.81 x Re in N-m 2. Frictional Torque T.F = Tf1 + Tf2 + Tf3 in N-m Tf1 = BT (T1/ (Tm-T1) in N-m t1=time taken for fall of speed at no load condition t2=time taken for fall of speed at no load condition 3. Break Power B.P = (2π x W x Re x g) / (60x1000) in KW. 4. Frictional Power Loss FP = (x N x Tf ) / 60000 inkw 5. Mechanical Efficiency mech = (B.P /(BP + FP) x 100 i% Where, g = Acceleration due to gravity = 9.81 m / sec 33
Graph: Tabulation: Thgraph drawn by B.P Vs mech Average Break Friction Break Friction mech Time taken to reach LOAD(kg) from 660 rpm to (sec) Torque Torque Power Power N-m N-m KW KW S.NO % W1 W2 W 560 460 360 W1-W2 rpm rpm rpm 1. 2. 3. 4. Result: Thus the Retardation test on engine in conducted and the. Frictional power loss mechanical efficiency at about three loads are found out. 34
10(a). STUDY OF STEAM GENERATORS Ex.NO: Date: Aim: To study the working of various types of steam generator (steam boilers) Study of steam generators: Introduction: A steam boiler is a closed vessel which boiler generator steam by transferring heat produced by burning of fuel to water. The steam boiler produced is used for power generation or process heating. Selection of steam generators: The selection of type & size of a steam generator depends on the following factors. 11. The power required & working pressure. 12. The geographical position of power house. 13. The fuel & water available. 14. The probable load factor. Classification of Boilers: The steam boilers are classified according to the following basic: 1. Flow of water & heat gases Fire tube boiler Water Tube boiler 2. Method of firing Internally fired Externally fired 3. Method of water circulation Natural circulation Forced circulation 4. Pressure developed Low pressure boiler High pressure boiler 6. Nature of service a. Stationary boiler b. Mobile boiler 35
7. Design of gas passage a. Single phase b. Multi-phase 8. Nature of service a. Stationary boiler b. Mobile boiler 9. Design of gas passage a. Single phase b. Multi-phase 10. Nature of service a. Stationary boiler b. Mobile boiler 11. Design of gas passage a. Single phase b. Multi-phase High Pressure Boilers: Modern high pressure boilers generate steam at a pressure more than 75 bar. Example: Babcock & Wilcox boiler, Lamont boiler, BHEL boiler. Lamont Boiler: A forced circulating boiler was first introduced in 1725 by Camont. The arrangement is shown in the figure. The most of sensible heat is supplied to the feed water passing through the Economizer. A centrifugal pump circulates the water equal to 8 to 10 times the weight of steam evaporated tubes and the part of water supplied drum. The large quantity of water circulated prevents the tubes from being overheated. To secure the uniform flow of feed water through each of parallel boilers circuits a choke is fitted all the enhance to each circuits. Bhell boilers: It consists of feed pump, a economizer a boiler drum, radiant & connective super heaters, FD fan, air pre heaters 1 & 2.Electro static precipitator 1D fan & chimney. The feed water from the hot well is pumped with the help of a feed pump to boiler from the through economy.in boiler drawn the fed water is circulated to number of valves in the furnaces with fuel is burnt. The feed water is evaporated into wet steam and the wet steam flows back to boiler drawn. In this it s supplied to prime mover through steam outlet. The hot blue gases from the furnace pars over radiant & connective super heaters to super heat the steam. Then it passes through the pre heaters economizer and pre heater.then the blue gases passes through the electrostatic precipitator. Result: Thus the working of various types of steam generator was studied. 36
10(b). STUDY OF STEAM TURBINE Ex.NO: Date: Aim: To study the working of various types of steam turbines. Study of steam turbines: Introduction: A steam turbine is rotary machine which is designed to covert the energy of high temperature steam into mechanical power. In this the steam is first expanded in a set of nozzles or passages upto exit pressure where in the pressure energy of steam is converted into kinetic energy. Classification of Steam Turbine: Steam turbines are classified according to: 1. Priciple of action of steam Impulse turbine Reaction turbine 2. Direction of steam flow Axial Radial Tangential 3. Number of pressure stages Single stage Multi stage 4. Method of governing Throttle Nozzle By-pass Combination of throttle, nozzle by pass Impulse Turbine: Velocity compound impulse turbine: Arrangement of velocity compounded impulse turbine is shown in fig. In this type of turbine steam expands in a set of nozzle from the boiler pressure up to the condenser pressure which converts its pressure energy into kinetic energy. This high velocity steam is passed over the rings of moving blades, each ring of moving blades being separated by a ring of 37
fixedblades. A part of high velocity steam is absorbed in the first ring of moving blades and remaining in the first ring of moving blades is passed to next ring of fixed blades. The function of fixed blades is to change the direction of flow of steam so that it can guide over the second ring of moving blades. The velocity of steam while passing over the fix blades is particularly constant except last for overcoming the friction losses. Again a part of steam velocity is absorbed in the second ring of moving blades & the process of absorbing the steam velocity continues till it finally wasted in exhaust. Pressure compounded Impulse Turbine Arrangement of velocity compounds impulse turbine is steam is shown in fig. In this type of turbine the total pressure drop does not take place in a single ring of nozzle, but it is divided up in between the set of nozzle ring steam from the boiler is partially expanded in the first ring of nozzle and then it is passed over the ring of moving blades till its velocity is absorbed. Exhaust from blades till its velocity is absorbed. Pressure Velocity compounded Impulse Turbine: Arrangement of velocity compounded impulse turbine is shown in figure. In this arrangement both the previous method velocity & pressure compounding are utilized. The total pressure drop of steam is due to expansion in each stage is also compounded. Reaction Turbine: Arrangement of velocity compounded impulse turbine is shown in figure. Unlike impulse turbine nozzle are not provided in this turbine and also there is a continous pressure drop in the rings of fixed and moving blades. The function of fixed blades, which also get nozzles is to change the direction of steam. So that it can enter into the ring of moving blades without shock the term reaction is used because the steam expands over the ring of moving blades giving a reaction on moving blades. Result: Thus the working of various types of steam generator (steam boilers) & steam turbine are studied. 38
11. PERFORMANCE AND ENERGY BALANCE TEST ON A STEAM GENERATOR Ex.NO: Date: Aim: To conduct the Performance and energy balance test on a steam Generator Apparatus required: Stop watch Beaker Procedure: 1. Keep the main steam control valve and the valves of the calorimeter (as described above) fully closed initially. 2. Supply the power to the main control panel to the digital voltmeter, ammeter, tachometer and temperature indicator. 3. Start the condenser cooling water pump and circulate cooling water through the condenser. Ensure that cooling water flows freely through the turbine casing bearing cooling water jacket the braided hoses. 4. Open the steam main valves and crack open the steam nozzle control valve to observe the turbine start spinning. 5. Apply some initial load (switch on a few load bulbs) first. Continuously monitoring the turbine speed, open the nozzle valve such that the turbine speed reaches about 2800rpm. Note: Do not exceed 3000rpm under any circumstances as the alternator is rated only for 3000rpm and any overs peed will damage the coil windings. 6. Observe the operating parameters rpm, pressure, alternator output voltage, current. 7. The turbine can be loaded further by switching on more bulbs and opening the second nozzle valve also. Alternatively, both nozzles can be opened partially. If the turbine speed tends to increase beyond the permissible speed, more bulbs are to be switched on. 8. Initially some steam may come out of the condenser along with condensate. After a few minutes, it will stop and only water will flow. If steam continues to come out, it indicates that either the cooling water flow rate is not sufficient or the cooling water temperature is too hot for the condenser to be effective. 9. The condensate is to be measured directly to determine the exact steam flow rate through the condenser and turbine. 39
10. Monitor the coolant water inlet and exit temperatures. Once steady state is reached, note down the temperatures and the orificemeter pressure gauge readings (to determine the flow rate) 11. Steam quality measurement: Open the needle valve V1 and outlet valve V3 and let the steam purge any air present inside the two chambers. Allow cooling water through the calorimeter condenser. Now, adjust the valve V1 such that a small quantity of steam flows through the separating calorimeter at first and then through the throttling calorimeter and finally is condensed. If steam pressure is increasing in the separating chamber, it implies that the condenser cooling is insufficient. So, increase the cooling water flow rate and/or close the valve V0 slightly. Once steady conditions are reached, note the pressure and temperature at the throttling calorimeter chamber. After a certain period of time (say 5 minutes), close V1 and measure the water collected in the separating chamber by opening valve V2 at its bottom. Also measure the water condensed in the condenser. 12. Repeat the experiment for other loads. Caution: Never run the turbine without any load. This may cause overspeed and damage the alternator which is rated for 3000rpm. Measured and observed data: Inlet steam line pressure P0 - Turbine rpm N - Voltmeter reading V - Ammeter reading A - Separating calorimeter pressure P1 - Throttling calorimeter pressure P2 - Throttling calorimeter temperature T3 - Moisture collected in separating calorimeter ms - Moisture collected in throttling calorimeter mt - Condenser cooling water inlet temperature TC1 - Condenser cooling water outlet temperature TC2 - Condenser orificemeter pressure PCO1 - Condenser orificemeter pressure PCO2 - Steam flow Rate (From Condenser) M - 40
Calorimeter calculations: m be the total mass flow rate of steam sampled by the calorimeter We have the following relations m = mt + ms... 1 h2 = h1 =hf1 + X1hfg1... 2 X1 = (h2 - hf1)/hfg1... 3 h1 is the enthalpy at P1 and h2 is the enthalpy at P2 and T2. X1 is the steam quality in separating chamber (Note: Steam condition 1 is normally wet and 2 is superheated due to the throttling - hf1 and hfg1 are obtained from saturated steam tables and h2 from superheated steam tables) For P1 = kg/ cm 2 hf1 = and hfg1 = (saturated steam) For P2 = and T3 = h2 = (super heat steam) X1 = (h2-hf1)/hfg1 X1 = = ( ) / mw be total moisture in steam sample mw= [ms + (1-X1) mt]... 4 = [ + ( ) ] mw = Line Steam Quality X = [1 - mw/(ms+mt)]x100 %... 5 = [1 / ( + )] x 100% X = X = 41
Calculation of Isentropic work: P0, X are inlet steam pressure and quality. Corresponding enthalpy and entropy h0 and s0 are determined form steam tables. For P0 = kg / cm 2, hf0 = and hfg0 = sf0 = and sfg0 = h0 = h f0 + X.hfg0 = + ( x ) h0 = s0 s0 = = sf0 + X.sfg0 = + ( x ) Exit pressure PE is atmospheric. Saturated steam properties for this condition are: For PE =1bar hfe = and hfge = sfe= and sfge = For isentropic expansion to exit pressure P E, s E = s 0.Hence, exit steam quality X E is determined from the relation: XE = (s0 -sfe)/sfge... 6 = ( ) / XE = Enthalpy at exit conditions (for isentropic expansion) are he = hfe + XE.hfgE = + ( x ) isentropic enthalpy drop: is he = h s=const = ( h0- he)...7 = ( - ) h s=const = KJ/kg Isentropic work W = M.( hs=const)... 8 = x KJ / hour = x / 3600 kw = kw 42
Calculation of Output Power: Voltmeter reading V = Volts Ammeter reading A = amps Alternator Output Power = V x A/1000 KW = ( x /1000) KW = KW Steam turbine output = Alternator output/0.7 KW (0.7 is the assumed alternator efficiency) = V x A/(1000 x 0.7) KW = KW Calculation of isentropic efficiency of turbine: Isentropic efficiency = Turbine Power/Isentropic work = / = Calculation of condenser effectiveness: Coolant water flow rate- Pressure drop in condenser orificemeter OP = (Pco1 Pco2) x 10 m of water = ( - x 10) m = m of water Coolant water flow rate Q = 0.00204 OP m 3 /sec = 0.00204 m 3 /sec = x x 6000 = Heat exchanger effectiveness of condenser = (Tc2-Tc1)/(TE-Tc1) (TE is the saturation temperature of exhaust steam at atmospheric pressure) = ( ) / ( ) = 43
Result: Thus the Performance and energy balance test on a steam Generator was studied. 44
45