Applied Thermodynamics Qb

P.A.C. RAMASAMY RAJA POLYTECHNIC COLLEGE, RAJAPALAYAM – 626108. (AUTONOMOUS INSTITUTION) III TERM MECHANICAL ENGINEERING (R & A/C) – 2041 APPLIED THERMODYNAMICS QUESTION BANK Prepared by,

C. Karthigeyan, B.E., Lecturer / Mech (R&A/C) Department.

Short Answer Questions: UNIT I 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41.

Define thermodynamics and give some applications. Define I) Force. ii) Mass iii) pressure. Define I) Weight ii) specific weight. Define I) volume ii) Specific volume. Define I) Density ii) Specific gravity. What are all the various types of pressure? Explain absolute and vacuum pressure. Explain gauge and atmospheric pressure. Define temperature and name the various scales in which it represents. Define N.T.P and S.T.P. Define I) Heat ii) Specific Heat Capacity. Define specific heat capacity at constant volume. Define specific heat capacity at constant pressure. Define I) Work ii) Mechanical work. Define adiabatic index. Define Power. Define the term system, surrounding and boundaries. Name the thermodynamic systems. Define I) Closed system ii) Open system iii) isolated system. Define intensive and extensive property. Define point and path function. Differentiate between stored and transit energy. Define potential and kinetic energy. Define internal change in energy. Define enthalpy. Define thermodynamic equilibrium. State the first and second law of thermodynamics. State zeroth law. Define perfect gas with example. Write down the laws of perfect gas. Define I) Boyle’s law ii) Charles’ law iii) Joule’s law. Define entropy. Distinguish between isothermal and adiabatic process. Identify the different thermodynamic process. Derive an expression for work done during isothermal process. Explain the second law of thermodynamics. What are all the difference between gas and vapor? Give two examples for each. Derive the characteristic equation of a perfect gas. Derive the relationship between Cp, Cv and R. o o 10 kg of steel, specific heat capacity 480 J/kgK is heated from 15 C to 100 C. How much heat is required? 3 A gas having molecular weight of 28 occupies a volume of 0.15 m at a pressure of 2 bar and a temperature o o of 20 C. Find the mass of the gas and the volume of the gas at 0 C and 1 bar pressure. Find also the density o of the gas at 0 C and 1bar pressure, the value of universal gas constant is Ru = 8314 j/kg mole K. 3 o 2 42. One Kg of a perfect gas occupies a volume of 0.85 m at 15 C and at a constant pressure of 100 kN/m . The gas is first heated at constant volume and then at constant pressure. Find Cp and Cv. 3 o 43. The density of oxygen at NTP is 1.43 Kg/m . What is its density at 10 bar and 200 C?

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44. A gas is compressed hyperbolically from a pressure and volume of 100 KN/m and 0.056 m respectively to a 3 volume of 0.007 m . Determine the final pressure and the work done on the gas. 2 45. A gauge fitted to a compressor records a pressure of 16.27 KN/m . Compute the corresponding absolute 2 pressure in kN/m . The local atmospheric pressure is 750 mm of mercury. 46. At a speed of 40 Km/hr, the resistance to motion of a car is 1KN. Determine the power out put of the engine at this speed, neglecting losses. o 47. Determine the volume of a tank which as to store 2 mole of any gas at 20 C and 300 Kpa. 3 o 48. A mass of 2.25 Kg of nitrogen is stored in a cylinder of 1.5m capacity, which is at 25 C. Determine the pressure of gas in the cylinder. 3 o 49. A vessel of capacity 3 m contains air at 30 bar and 60 C. Some air is used and after use the final state is o stored is noted as 1.5 bar and 25 C. Determine the mass of air used. o 3 50. Nitrogen at 2 bar and 20 C occupies a volume of 0.15 m . Determine the mass. Also find the volume of this gas at NTP and density at STP.

UNIT – II 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35.

Define steady flow system. Explain the steady flow energy equation. Name the applications of steady flow energy equation. Define control volume. Write down the equation of SFEE. Define air cycles and air standard efficiency. List the types of thermodynamic cycles. Explain reversible and irreversible process. State the assumptions in deriving air standard efficiency. Explain Carnot cycle with neat sketch. Explain why the efficiency of Carnot cycle is High. Sketch the p – V and T – S diagram for the Otto cycle. Sketch the p – V and T – S diagram for the Diesel cycle. Sketch the p – V and T – S diagram for the Dual cycle. Distinguish between Otto cycle and Diesel cycle. Distinguish between reversible and irreversible process. Write down the steady flow energy flow equation for a reciprocating compressor. What do you mean by reversible cycle? State the conditions for reversibility. Explain the effects of Cut off ratio and compression ratio on the efficiency of diesel cycle. Derive an expression for the air standard efficiency of Carnot cycle. Define the following 1) Explosion ratio. 2) Efficiency ratio and drawing factor. Define swept volume and clearance volume. What is an indicator diagram? Define relative efficiency. Sketch the p – V and T – S diagram for the reversed Carnot cycle. No engine can work on Carnot cycle. Why? Find the percentage increase in efficiency when the compressor ratio for a petrol engine is raised from 5 to 6. Assume Gamma = 1.4. Calculate the air standard efficiency of an engine working on Otto cycle, if the pressure at the beginning and 2 2 the end of compression are 103.5 kN/m and 827.5 KN/m respectively. Take Gamma = 1.4. Find the air standard efficiency of a diesel cycle engine if the cut off ratio is 6% of the stroke and the th clearance is 1/13 of the stroke. Take Gamma = 1.4. A Carnot engine working between 650 K and 310 K produces 150 Kj of work. Find 1) Thermal efficiency 2) heat added during the process. o Air expands from 3 bar to 1 bar in a nozzle. The initial velocity is 90 m/s and temperature 150 C. Estimate the final velocity. Cp = 1.005 kj/kg.K. o o The temperature limits for a Carnot cycle using air as a working substance are 420 C and 10 C. Calculate the efficiency of the cycle and ratio of adiabatic expansion. Find the loss in ideal efficiency of a diesel engine with compression ratio 15 by dealing the fuel cut off ratio from 5% to 10% of the stroke. An engine working on Otto cycle has the cylinder diameter of 150 mm and stroke of 225 mm. the clearance 3 volume of 0.00125 m . Find the air standard efficiency of the engine. o A reversible Carnot engine is used for heating a building. It supplies 200 MJ/hr to the building at 20 C. The o outside air is at -5 C. Find the power of the motor required.

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UNIT III 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51.

What are the different types of piston rings? Explain the function of the rings in I.C engines. Draw the line diagram of a simple carburettor and name the parts. Draw and explain the typical port time diagram of a two – stroke cycle diesel engine. How is I.C engines classified? What are the desirable properties of good lubricant? Sketch the different fuel nozzle in diesel engine and name them. Sketch and name the nomenclature of I.C engine. What do you mean by scavenging? Explain about the overhead valve mechanism with neat sketch. Explain about fuel injection with a sketch. Draw and explain about a filter used for petrol engine. Write about hit and miss governing. Draw the PTD of a petrol engine and indicate the events on it. Draw a layout of fuel supply system in petrol engine and write the function of each element. Write down the function of advanced carburettor. What do you mean by compression ignition system and spark ignition system? Write down the merits and demerits of air-cooling. What are the effects of supercharger? What do you mean by supercharger Write short note on cylinder block, piston rings, flywheel and governor. Compare the difference between petrol engine and diesel engine. Explain the need for cooling I.C engines. Write down the major different between S.I engine and C.I engine. What are the functions of lubrication in I.C engine? Sketch the Coil ignition system. Name the types of carburettor. Distinguish between four stroke and two-stroke engine. Sketch the AC mechanical fuel pump. Sketch the electrical fuel ignition system. What do you understand from governing in I.C engines? Differentiate between air-cooled and water cooled system. State the merits of water-cooling system. List the properties of lubrication. Name the types of lubrication system. Compare supercharger and turbocharger. Compare between Wet liner and dry liner. Name the components of I.C engines. Name the materials used for the components of I.C engines. Sketch the valve operating mechanism. Sketch the layout of fuel supply system in Petrol engine. Sketch the layout of fuel supply system in Diesel engine. Name the types of ignition system. Define quality and quantity function. List the types of lubrication system. Sketch the pressure lubrication system. Name the type of scavenging. What do you mean by Detonation in I.C engines? State the effects and application of super charger. Explain the side valve mechanism. List the requirements of a carburettor. What is the purpose of oil filter?

UNIT IV 1. 2. 3. 4. 5. 6.

What are all the requirements of good fuel? What is meant by excess air? Why excess air is supplied for the combustion of fuel. What is calorific valve of the fuel? Define HCV and LCV of the fuel and state the different between them. What is Morse test? Explain the same Define 1) Indicated power. 2) Brake power and why B.P is less than I.P.

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7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45.

46. 47. 48. 49. 50.

Define various efficiency of an I.C engines. Explain ultimate analysis. List the merits and demerits of various fuels. How flues are classified? Describe the orsat apparatus used for the analysis of exhaust gas. Explain bomb calorimeter. Explain air pollution. Name the causes of air pollution. List the effects of pollution. Name the controlling methods of pollution. What is all the complete requirement of complete combustion of fuel? Explain Stoichiometric. Define 1) Indicated thermal efficiency 2) Brake thermal efficiency. Define 1) Mechanical efficiency 2) Relative efficiency. List the procedure for conducting Morse test. Sketch a sheet balance sheet and name all the significant. List the purpose of testing in I.C engines. Define mean effective pressure. Define indicated mean effective pressure. What is the purpose of heat balance sheet of an engine? State the advantages of liquid fuels. Define atoms and molecules. Name some of the liquid and gaseous fuel. Explain what is meant by ultimate and proximate analysis of fuel. Name the different brake power measuring equipments. State the losses due to friction power. List the procedure for preparing heat balance sheet. What are the various methods of measuring the indicated power of an engine? Distinguish between brake power, indicated power, friction power. State the assumptions made in conducting Morse test. Explain performance of I.C engines. Name the fuels used in I.C engines. What are the different methods available to measure the power output for an engine. Names the different methods available to measure the power output for an IC engine. Estimate HCV and LCV of a fuel, whose composition by weight is C = 80% H2 = 15% and residual mater 5%. Calculate the mass of air to be supplied for the combustion of a fuel containing 75% C, 8% H2, and 3% O2 rest ash. If 50% excess air is supplied. The ultimate analysis of a coal by weight is as follows: C 78%, H2 3%, O2 3%, S 1% ash 10% and moisture 5% excess air supplied is 30%. Determine the products of combustion by mass and percentage. Calculate the mass of air to be supplied for the combustion of a fuel containing 75% carbon; 8% H2, if 80% of excess air is supplied. A single cylinder internal combustion engine working on 4-stroke cycle has a cylinder bore of 100 mm diameter and a piston stroke of 150 mm. speed of the engine is 500 r.p.m. If the mean effective pressure is 2 650 kN/m , calculate the indicated power developed by the engine. A single cylinder fore stroke petrol engine develops an indicated power of 7500 W. the effective pressure is 2 670 kN/m and the piston diameter is 100 mm. Calculate the average speed of the piston. In a test on diesel engine the SFC was obtained, as 260 g/KW-hr. the calorific value of the fuel is 4200 KJ/Kg. determine the brake thermal efficiency. In a case of a 10 KW constant speed engine, the friction power was 2.3 KW. Determine the mechanical efficiency at 0, 2.5, 5 7.5, and 10 KW output. A diesel engine has a compression ratio of 14:1 and the fuel supply is cutoff at 0.08 of the stroke. The calorific value of fuel is 43600 kJ/Kg. if the relative efficiency is 50%, estimate the mass of fuel required per KW-hr. An engine working an constant volume cycle has a compression ratio of 8, it uses petrol having a calorific value of 4400 KJ/Kg. if the brake thermal efficiency of the engine is 60% of the air standard efficiency, determine the specific fuel consumption in Kg/KW-hr.

UNIT V 1. 2. 3. 4.

How air compressors are classified Derive an expression for the volumetric efficiency of an air compressor. Compare open cycle gas turbine and closed cycle gas turbine. With neat sketch explain the working of multistage air compressor.

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5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36.

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What is intercooler? Write the advantages of rotary air compressor. Explain the working of centrifugal compressor. Distinguish between reciprocating and rotary compressor. Define positive displacement and negative displacement. What are the uses of compressed air? What are all the special features of rotary compressor? How are gas turbine classified. Distinguish between ram jet and turbo jet. What are all the requirements of a combustion chamber? What are all the applications of gas turbine? Explain the working of a turbo propeller engine with neat sketch. Explain the various efficiency of air compressor. Explain briefly about inter cooler and inter cooling. What is jet propulsion? Explain how a reheater improves the performance of a gas turbine. Write short note on constant volume gas turbine. Write down the merits and demerits of gas turbine. Explain rocket propulsion. Explain regeneration and reheating. State the advantages of gas turbine over I.C engines. Compare between rocket and jet propulsion. Explain clearance volume and its effects. Compare between aircraft and industrial gas turbine. Sketch the multi cylinder air compressor. Sketch the axial flow rotary compressor. Compare centrifugal and axial flow compressor. Name the factors in maintenance of compressor and explain any one. Define pressure ratio and clearance ratio. List the effects of clearance volume. State the merits of multi stage air compressor. 2 2 A compressor compresses air from 100 KN/m to 700 KN/m . The clearance volume is 2.13 liters and compression and expansion are polytrophic, n = 1.3 for each. If the volumetric efficiency of the compressor is 85%, determine 1. The stroke volume, 2. Diameter of he cylinder, if the length of stroke is 300 mm. Estimate the power required of a single stage double acting air compressor given the following particulars. Cylinder diameter – 280 mm, Stroke – 200 mm, clearance volume – 3% of the stroke volume; delivery pressure 7.5 bar. Suction pressure – 1 bar, speed – 350 rpm. The compression and expansion ratio = 1.3. 3 A single cylinder reciprocating air compressor has a volume of 0.1 m . The intake condition of air is one bar o and 15 C. The air after compression attains a pressure of eight bar. It is delivered to the receiver at a 1.3 constant pressure. The compression takes place according to the law p.V = C. determines 1. Temperature at the end of the compression, 2. Network done on air per cycle. 3 2 o It is required to compress 3 m of air per minute from a pressure and temperature of 100 KN/m and 15 C to a 2 pressure of 700 KN/ m in a compressor having an isothermal efficiency of 77%. What is the indicated power of compressor? Determine the powers required by a two-stage compressor with perfect inter cooling with a suction pressure o of 1 bar and temperature of 30 C and the final pressure is 25 bar. The volume of air handled at inlet condition 2 1.3 is 30 m /hr. the law of compression is p.V = C.

Essay type questions: UNIT I 1. State and explain the law of thermodynamics. 2. State and explain the Kelvin plank statement of second law of thermodynamics. Derive an equation for the work done during constant pressure with p – V diagram. 3. Explain 1. Boyle’s law, 2. Charle’s law and Joul’s law. 4. Define energy and explain the different types of energies. 5. Derive the characteristic equation of a perfect gas. 6. Derive an expression for the work done during adiabatic process. 7. Derive an expression for the work done during isothermal process. 8. Explain the different between adiabatic and isothermal process. 9. Derive the relationship between Cp , Cv and R.

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10. What do you mean by thermodynamic system? State the three types of thermodynamics system. o 2 11. A quantity of air occupies a volume of 30 liters at a temperature of 38 C and a pressure of 104 KN/ m . 2 Heating at constant volume raises the temperature of the air till the pressure is 208 KN/m . Find the final temperature, external work done, change in enthalpy, change in internal energy, and change in entropy. Assume suitable process. o 12. Air at one bar and 40 C is compressed to one by tenth of its original volume adiabatically. Determine the final 3 pressure, final temperature and work done on / m of air take R = 0.287 KJ / KgK. And gamma as 1.4 for air. 3 o 13. 0.35 m of air at 22 C and under atmospheric pressure is heated under constant volume at a temperature of o 100 C. Assume Cp = 1 KJ / KgK and Cv = 0.7 KJ/Kgk. Find 1.Mass, 2. The final pressure, 3. Heat transfer, 4. Change in internal energy and work done. O 1.23 14. 0.65 Kg of air at 14 bar and 210 C is expanded to four times the final volume according to the law p.V = C. Determines 1. The initial and final volume of the gas, 2. Final temperature and pressure of the gas, 3. Work done, 4. Change in internal energy, 5. Heat transfer, 6. Change in entropy. Assume R = 287 KJ/KgK. 3 15. A gas having molecular weight 28 occupies a volume of 0.15 m at a pressure of 2 bar and a temperature of o o o 20 C. find the mass of the gas at 0 C and one bar pressure. Find also density of gas at 0 C and 1 bar Ru = 8314 J/Kg mole k. 5 2 5 2 16. 2 Kg of gas at 8 X 10 N / m expands adiabatically till the pressure falls to 4 X 10 N / m during the process oC o 1, 20,000 Nm of work done by the system and the temperature falls 377 to 257 C. calculate the value of index of expansion and characteristic gas constant. o 3 17. A gas at a pressure of 4 bar and temperature 27 C occupies a volume of 3.2 m . If the mass is 1.2 kg. Determine the gas constant. o 3 18. A gas whose pressure, temperature and volume are 5 bar, 185 C and .0.23 m respectively has it s state o change at constant pressure until. Its pressure becomes 70 C. Determine 1. The work done, 2. Change in internal energy, 3. The heat transfer during the process, R = 290 J/KgK, Cp = 1.005 KJ/KgK. 0 19. 0.5 Kg of air at 180 C expands adiabatically to 3 times its original volume. During the expansion the o temperature is decreases to 20 CD work done during expansion is 53KN. Find Cp , Cv and R. 3 20. 0.25 Kg of air at a pressure of 1 bar occupies a volume of 0.3 m . If the air expands isothermally, to a volume 3 of 0.9 m . Determine 1. The initial temperature, 2. The final temperature, 3. External work done, 4. Change in internal energy, 5. Heat absorbed by air and change in entropy. Assume R = 0.29 KJ/KgK. 5 2 o 21. 2 Kg of an ideal gas is compressed polytropically from a pressure of 1.5 X 10 N/m and at 16 C to a pressure 5 2 1.3 of 2.5 X 10 N/m . According to the law p.V = C. determine 1. The initial volume, 2. Final volume, 3. Work done, 4. Change in internal energy. 5. Heat transfer. Assume R = 0.28 KJ/KgK and Cp = 1 KJ/KgK. 22. The decrease in internal energy of 3 Kg of an ideal gas is 1028 KJ when pressure decreases from 7 bar to 1.4 3 3 bar and volume increases from 1.5 m to 4.5 m . Assume Cp = 1 KJ/KgK and Cv = 0.71 KJ/KgK. Find the change in enthalpy of the gas and its initial and final pressure. 3 o 23. 2 Kg of gas occupies 0.7 m had an original temperature of 15 C. It was then heated at constant volume, until o its temperature becomes 135 C. How much heat was transferred to the gas and what was its final pressure? Take Cv = 0.72 KJ/KgK and R = 0.29 KJ/KgK. 2 o 24. A gas at a pressure of 1680 KN/M and temperature of 350 C is expanded adiabatically to a pressure of 120 2 o KN/m . The gas is then heated at constant volume until it gains reaches 350 C, when its pressure is found to 2 2 be 264 kN/m . Finally the gas is compressed isothermally until the original pressure of 1680 KN/m is obtained. Sketch the p –V and T – S diagram for this process. If the gas has a mass of 0.23 Kg, find 1. The value of adiabatic index. 2. The change in internal energy during adiabatic expansion. Take Cp = 1.005 KJ/KgK. o 25. 0.2 Kg of air at a pressure of 1.1 bar and 15 C is compressed isothermally to a pressure of 5.5bar. Calculate 1. The final volume, 2. Heat rejected 3. Change in entropy and 4. Change in internal energy. Assume R = 0.293 KJ/KgK.

UNIT II 1. Derive an expression for air standard efficiency of an Otto cycle. 2. Derive an expression for the air-standard efficiency of diesel engine. 3. Steam enters a turbine at a velocity of 12 m/s and specific enthalpy, 2900 kJ/Kg. At the exit of the turbine the steam velocity is 30 m/s and the specific enthalpy 2400 kJ/Kg. The heat lost during the flow rate is 85 Kg/s. determines the work output from the turbine. 4. In a diesel engine, the compression ratio is 13:1 and the fuel is Cut-off at 8% of the stroke. Find the air standard efficiency of the engine take gamma = 1.4. 1.2 5. An indicator diagram taken on a diesel engine shows the compression curve follows p.V = C. the pressure th th 2 at two points lying on the compression curve is 1/3 and 8/2 of the stroke are 160 Kpa and 1600 KN/m . Find the compression ratio of the engine. If Cut-of ratio occurs at 7% of the stroke, calculate the air standard efficiency.

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6. The following data refer to a four-cylinder petrol engine: 1. Total swept volume – 2000 c.c, 2. Clearance o volume – 60c.c per cylinder, 3. Maximum cycle temperature – 1400 C. At the beginning of compression, the 5 2 o pressure is 10 N/m and the temperature is 24 C. Calculate the efficiency of Otto cycle and mean effective pressure. th 7. A perfect heat engine working on a Carnot cycle converts 1/6 of the heat input into work. When the o temperature of the sink is reduced to 62 C, the efficiency is doubled. Find the temperature of the sink and source in each case. 1.25 8. An indicator diagram taken on a diesel engine shows the compression curve follows p.V = C. the pressure th th at two points lying on the compression curve is 7/8 and 8/2 of the stroke are 1.6 bar and 16 bar. Find the compression ratio of the engine. If Cut-of ratio occurs at 6% of the stroke, calculate the air standard efficiency. 9. Find the percentage increase in efficiency when the compression ratio for a petrol engine is raised from 5 to 6. Assume gamma = 1.4. 10. A diesel engine works with compression ratio of 16. The heat is supplied during 10% of the strike. The inlet 3 conditions are 100 Kpa and 300 K. The engine uses 0.05 m of air per second. Determine the thermal efficiency of the cycle and indicated power of the engine. 2 2 11. What is meant by control volume? Explain air expands from 350 KN/m to 100 KN/m in a nozzle. The inlet 0 velocity and temperature are 100 m/s and 160 C. Determine the exit velocity. Take Cp = 1.005 kJ/KgK. 12. In an ideal constant volume cycle, the pressure and temperature of the air at the beginning of compression 2 o are 97 KN/m and 50 C respectively. The ratio of compression is 5:1. The heat supplied during the cycle is 970 KJ/Kg of the working fluid. Determine 1. Maximum temperature of the cycle, 2. The thermal efficiency of the cycle and 3. The work done during the cycle per kg of working fluid. Assume gamma = 1.4 and Cv = 0.717 kJ/KgK. 13. One kg of air is taken through a constant volume cycle and compressed through a volume ratio of 6:1, the 2 o initial pressure and temperature being 103 KN/m and 100 C respectively. Heat is added at constant volume 2 until the pressure is 3450 KN/m and then expands adiabatically to its original volume. It is cooled at constant volume to its original state. 14. Find the air standard efficiency of a diesel cycle if the cut off ratio is 6% of the stroke and the clearance th volume is 1/13 of the stroke. Take gamma = 1.4. 15. A compression ignition engine working on a diesel cycle has the following particulars. Clearance volume – 3 250 cm ; cylinder diameter – 150 mm. Stroke – 200 mm; find the air standard efficiency, if the engine receives th the heat during 1/10 of the stroke. 16. Find out the power output of a diesel engine working on a standard diesel cycle with a compression ratio 16 o and an air flow rate of 0.25 Kg/s. the final condition of air is at 1 bar pressure absolutely and 27 C temperature. Heat added per cycle is 2500 KJ/Kg. Assume Cp = 1 KJ/KgK and Cv = 0.714 KJ/KgK. 17. In an ideal diesel cycle the compression ratio is 15:1 and the expansion ratio is 7.5:1. The pressure and 2 o temperature at the beginning of compression are 98 KN/m and 44 C respectively and the pressure at the end 2 of expansion is 258.6 KN/m . Determine 1. The maximum temperature of the cycle and 2. The thermal efficiency of the cycle. 2 18. An engine uses air as the working substance. At the beginning of compression the pressure is 90 KN/m and o the temperature is 40 C. During the adiabatic compression, the volume is reduced to one sixteenth of its valve of the beginning of compression stroke. Heat is then added at constant pressure until the temperature is o 1400 C. The stroke is completed by adiabatic expansion until the initial volume is reached, when a constant volume closes the cycle. Take gamma = 1.4; Cp = 1.004 KJ/KgK. 1. Sketch the p – V diagram for the engine. 2. Determine the thermal efficiency of the cycle. 3. Calculate the pressure and temperature at all point of the cycle. 19. In an ideal constant volume cycle, the pressure and temperature at the beginning of compression is 6:1. The heat supplied during the cycle is 930 KJ/Kg of working fluid. Determine 1. The maximum temperature of the cycle. 2. The thermal efficiency of the cycle. 3. Work done during the cycle/Kg of working fluid. 3

20. An ideal engine has a clearance volume of 0.00025 m and a bore and a stroke of 152.5 mm and 200 mm 2 o respectively. A change of air at 100 kN/m and 20 C is taken into the cylinder and compressed adiabaticlally. o After combustion at constant pressure the temperature is 1096 C. The expansion which follows is adiabatic and original volume is reached after expansion. The cycle is closed by constant volume process finally and original state is restored. If gamma is 1.4, determined 1. The temperature and pressure at the end of the compression. 2. The temperature and pressure after expansion and 3. The ideal thermal efficiency of the cycle. 21. A diesel engine works on diesel cycle using air as a working fluid. The pressure and temperature of the air at o the beginning of the compression stroke are 100kpa and 30 C. The compression ratio is 16 and the expansion ratio is 12. Calculate the temperature and pressure at each point of the cycle. Also find the thermal efficiency of the cycle, take gamma = 1.4.

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22. A compression ignition engine has a stroke of 270 mm and a cylinder of 165 mm. The clearance volume is 3 0.000435 m and the fuel ignition take place at constant pressure for 4.5 percent of the stroke. Find the efficiency of the engine assuming it works a diesel cycle. If the cut off ratio is increased to 7% with the compression ratio unchanged, find the change in air standard efficiency. 23. A closed cycle gas turbine using air as a working fluid on brayton cycle. The pressure range of the cycle is 2 o o bar and 10 bar and the temperature range is 30 C and 600 C. Determine the thermal efficiency and the plant capacity, if the flow of air is 20 kg/s. 24. A Carnot cycle works between the temperatures limits 900K and 300K and pressure limits of 60 bar and 1 bar. Determine 1. Pressure and temperature at all point of the cycle. 2. Work done per kg of air and 3. Thermal efficiency. o 25. An efficient engine in a mountains region using hot spring water at 57 C receiving 420 kJ/min from the source o is said to reject 300 KJ/min to the melting ice at 0 C. Comment on the engine efficiency.

UNIT – III 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30.

With a neat sketch explain the working principle of a four-stroke diesel engine. Describe with a neat sketch the working of a valve mechanism. Briefly describe about a CAV fuel pump with a neat sketch. With a neat sketch explain the working of an electronic ignition system. Describe with a line diagram about the lubrication system adopted in automobile. Explain the following: 1. Carburetion. 2. Governing. 3. Scavenging and oil filter. With a neat sketch explain the working of starting and accelerating circuits of solex carburetor. Explain the magneto ignition system used in S.I engines with a line diagram. Explain the different types of cooling system employed in I.C engines. What are the different methods of lubrication I.C engines? Explain pressure system of lubrication with a neat sketch. Write the working of simple carburetor with sketch. State its disadvantages. With a line diagram explain the working of electronic ignition system. Briefly, describe various methods of governing employed in I.C engines. With a neat sketch, explain the working of starting and accelerating circuits of solex carburetor. Describe the working of a two-stroke cycle petrol engine with neat sketches. Write down the classifications of I.C engines. With a line diagram explain the working of coil ignition system. With a neat sketch explain the working of diesel fuel feed pump. With a neat sketch explain the working of pressure lubrication system. Briefly, explain the supercharger and turbocharger. Draw a typical valve-timing diagram of a four-stroke cycle diesel engine and explain. Compare four stroke cycle and two-stroke cycle operation and point out applications in which each is popular. What are the desirable properties of a good lubricant? Write brief notes on the following: 1. Cylinder block. 2. Piston. 3. Piston rings. 4. Connecting rod and 5. Crankshaft. Briefly, explain the scavenging process. Compare air-cooled and water-cooled system in I.C engines. Explain any one type of oil pumps. Explain the A.C mechanical fuel pump. State the merits and demerits of four stroke and two-stroke cycle engine. Explain any one type of lubrication system.

UNIT – IV 1. Describe the Orsat apparatus and explain how it is used for analysis of exhaust gas. 2. State the assumptions made in air standard efficiency. Derive an equation for the air standard efficiency of Carnot cycle. 3. With an example show how the volumetric analysis of the fuel is converted into gravimetric analysis. 4. How will you find out the CV of a gaseous fuel using Junker’s gas calorimeter? Explain with a neat sketch and give the methods of calculation. 5. State the reason for atmospheric pollution and explain various methods of controlling exhaust emission. 6. Explain the procedure for preparing heat balance sheet. 7. The percentage composition of the fuel by mass is given as C - 80%; H2 - 10%: and S - 5%. The fuel gas volumetric analysis is given as CO2 - 10%: CO - 1%: O2 - 10% and N2 - 79%. Determine 1Kg of coal 1. The maximum mass of air 2. The actual air 3. The excess air supplied.

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8. In a trial on an oil engine the following data were required: Duration of trial – 30 min: Speed – 1750 r.p.m: Brake power – 330 Nm: Fuel consumption – 9.35 Kg of calorific value of 42300 KJ/KgK. Jacket cooling water circulating – 483 Kg: Inlet and outlet temperature – o o o 17 C and 77 Crespectively. Air consumption 182 Kg: exhaust gas temperature – 486 C: Atmospheric o temperature – 17 C. Calculate the brake power: Indicated thermal efficiency, specific fuel consumption on BP basis, if mechanical efficiency is 83%. Assume specific heat of gas 1.25 KJ/KgK. Draw up an energy balance in KJ/min. 9. A fuel oil consists of the following percentage analysis by mass 82% C, 12% H2, 2% O2, 1% N2. Determine stoichiometric mass of air required to completely burn the fuel and also determine the products of combustion by mass as a percentage. 10. A six cylinder four stroke engine had a bore to stroke ratio of 3650:500 mm. During the trial, following results 2 were obtained. Mean area of indicator diagram – 0.00075 m , length of indicator diagram – 0.075 m, Spring 2 number – 70,000 KN/m per m of compression, Brake power – 14KNm, Speed – 500rpm, Fuel consumption – 240 Kg/Hr. calculate 1. Indicated power, 2. Brake power, 3. Mechanical efficiency, 4. Specific fuel consumption. 11. A fuel contain 92% carbon; 4% hydrogen; 2% sulphur; 1.5% oxygen: 0.5% Ash. It is supplied with 50% of excess air. Find the gravimetric composition of the product of combustion. 12. The following results were obtained during a Morse test on a four stroke petrol engine: bore – 75 mm: stroke – 100 mm; fuel consumption – 0.1 kg/min. CV – 4200 KJ/Kg; clearance volume of each cylinder – 98.2 cc. Bp developed with all cylinders working – 15.1 KW. Bp developed with nos. 1,2,3, & 4 cylinders cutout is respectively 10.44 KW; 10.59KW; 10.67KW; and 10.52KW respectively. Determine 1. Mechanical efficiency, 2. Efficiency ratio. 13. During a test on a four stroke cycle oil engine, the following data were obtained; swept volume of the cylinder 2 = 14 liters; speed = 400 rpm; brake load = 77 kg; brake drum radius = 0.7 m; Imep = 567 KN/m . Determine the indicated power, brake power and mechanical efficiency. 14. An engine working on ideal constant volume cycle has a piston of 120mm diameter and 120mm stroke. The clearance volume is 0.2 lit. If it’s relative efficiency is 40%. Calculate the actual thermal efficiency. Take gamma = 1.4. 15. The percentage consumption of a fuel by mass is given as C – 80%; H2 – 10%; and S – 10%. The volumetric analysis of fuel gas is given as Co2 – 10%; CO – 1%; O2 – 10% and N2 – 79%. Determine per Kg of coal – 1. Mmin 2. Mtot 3. Mex. 16. The following observations were made in determining the HCV and LCV of coal gas; 1. Volume of gas used = 3 o 0.06m ; 2. Mass of water circulated = 9.8 Kg; 3. Rise in temperature of cooling water = 6.3 C 4. Pressure of o gas tested above atmosphere = 45 mm of water; 5. Temperature of gas tested = 14 C; 6. Barometric pressure = 750 mm of Hg; calculate the HCV and LCV at N.T.P. fuel contains 1.75% of hydrogen. 17. In a test on cylinder oil engine working on four-stroke cycle and fitted with a simple rope brake the following readings were taken. Effective diameter for flywheel – 0.625 m; net load on brake wheel – 170 N; speed rpm indicated mean effective pressure – 7.7 bar. Diameter of the cylinder – 100 mm; stroke – 150 mm; fuel used – 0.332 Kg/Bp-hr; calorific value of the fuel – 42000 KJ/KgK. Calculate 1. BP; 2. IP; 3. Mechanical efficiency; 4. Indicated thermal efficiency. 18. Find the efficiency ratio of a diesel engine compared with the corresponding air cycle in which fuel is cut off at th 1/14 of the stroke. Compression ratio is 15 and it consumes 0.18 Kg of oil per IP-hr having a calorific value 42000 KJ/KgK. 19. A four cylinder four stroke petrol engine 70 mm bore and 90 mm stroke was tested at full throttle at 0.064 Kg/min. the power measurements were as follows; 1. With all cylinder working – 12.07 KW; 2. With cylinder 1 cutoff – 8.68 KW; 2. With cylinder 2 cutoff – 8.61 KW; 3. With cylinder 3 cutoff – 8.53 KW; 4. With cylinder 4 cutoff – 8.64 KW; CV of fuel 44000 KJ/KgK. Clearance volume of each cylinder is 0.07 lit. Estimate IP, thermal efficiency and efficiency ratio. 20. A single cylinder oil engine working on four stroke cycle has a bore of 110 mm and stroke 130 mm and runs at 600 rpm. The mean effective pressure is 6 bar. It consumes 10 cc of fuel in 28 seconds. The diesel oil used is having a CV of 42000 KJ/KgK and the specific gravity is 0.85. The engine cooling water enters at a o o temperature of 18 C and leaves at 60 C. The quantity of cooling water circulated is 1.5 l.p.m. The brake wheel diameter is 850 mm and rope diameter is 20 mm. The net load on the brake is 0.11 KN. The exhaust o gas temperature is 420 C and specific heat is 1 KJ/Kgk. The air fuel ratio is 22:1 by weight. Room o temperature is 30 C. Draw the heat balance sheet on hour basis. 21. The following readings are obtained during a test on a four stroke oil engine: Bore = 100 mm, Stroke = 115 mm, Speed = 1650 rpm, Fuel used = 0.2 Kg/ min, Calorific value of fuel = 41900 KJ/KgK, net load on the brake drum = 390 N, Circumference of the brake drum = 3.3 m, mechanical efficiency = 805, determine 1. Brake thermal efficiency, 2. Indicated thermal efficiency, 3. Indicated mean effective pressure.

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22. The following results were obtained during a Morse test on four-stroke petrol engine: BP with all cylinders working = 11.92 KW, BP with cylinder 1 cut out = 8.46 KW, BP with cylinder 1 cut out = 8.60 KW, BP with cylinder 1 cut out = 8.54 KW, BP with cylinder 1 cut out = 8.46 KW, BP with cylinder 1 cut out = 8.50 KW. Calculate the mechanical efficiency of the engine. If the fuel consumption is 3.5 Kg/hr, find the indicated thermal efficiency. Calorific value of the fuel is 42000 KJ/Kg. 22. A fuel oil has the following analysis by weight. C – 85%, H2 – 12.5%, O2 – 2%, and the residue 0.5%. The dry Fuel gas has the following composition by volume. CO2 – 9%, CO – 1% O2 – 7.7% and N2 – 82.23%, determine the air fuel ratio. 24. The following data refer to a calorific value test of a fuel by means of a gas calorimeter. Volume of gas used = 3 o 0.7 m . Amount of water heated = 25Kg. Rise in temperature of cooling water at inlet and outlet = 14 C. 3 Amount of steam condensed = 0.028 Kg. Find the higher and lower calorific value per m at S.T.P. take the heat liberated in condensing water vapor and cooling the condenser as 2470 KJ/Kg. Assume Cp for water as 4.19 KJ/KgK. 23. The percentage composition of a fuel by mass ig given as C – 80%; O2 – 10% and S – 10%. The flue gas volumetric analysis is given as CO2 – 10%; CO – 1%; O2 – 10%; and n2 – 79%. Determine per kg of coal 1. The minimum mass of air required. 2. The actual mass of air required. 3. The excess air supplied. 24. The following particulars were obtained during the trial on a four-stroke gas engine. Duration of trial – 1 hr, revolution – 16000, number of missed cycles – 600, net brake load – 1600 N, effective brake circumference – 400 mm, mean effective pressure – 8 bar, gas consumption – 22000 lit, calorific value of gas at supply condition – 20 KJ/lit, cylinder diameter – 250 mm, stroke – 400 mm, compression ratio – 6.5. Estimate 1. Indicated power, 2. Brake power, 3. Brake specific fuel consumption. 4. Brake thermal efficiency and 5. Relative efficiency. 25. Following data are available for a four stroke petrol engine: Air fuel ratio by weight – 15.5:1, CV of fuel – 45000 KJ/Kg, mechanical efficiency – 80%, Air standard efficiency – 53%, relative efficiency – 70%, o volumetric efficiency – 80%, stroke /bore ratio – 1.25, suction condition – 1 bar and 27 C, brake power – 75 KW, engine speed – 2400 rpm. Calculate 1. Compression ratio, 2. Indicated thermal efficiency, 3.Specific fuel consumption, and 4. Bore and stroke.

UNIT V 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

Explain with neat sketch the working of a turbo jet engine. Explain the working of ram jet engine with neat sketch. What is the application of fuel turbine? Give the advantages of the gas turbine over IC engines. Write the classification of air compressor. Write neat sketch explain the working of a multistage compressor. What is intercooling? Derive the expression for the volumetric efficiency of air compressor. Explain the working principle of an open cycle gas turbine with sketch, P-V diagram and T-S diagram. Explain how the performance of a gas turbine unit can be increases by using an inter cooler and regenerator. Write down the merits and demerits of gas turbine. Briefly, explain the maintenance of air compressor. 2 o It is required to compress 2.5 mm of air from a pressure and a temperature of 110 KN/m and 18 C 2 respectively to a pressure of 750 KN/m in a compressor having an isothermal efficiency of 75% calculate the indicated power of the compressor. o 11. An air compressor receives air 1.05 bar and 14 C and compressor it to 8bar. The temperature of the air o n delivered is 150 C. The compression follows the law p.V =C. calculates the value of index ‘n’. The delivery 3 rate is 1.4 m of free air per min. ignore temperature changes during suction and delivery. Find the power saved if the compression takes place isothermally. 12. Estimate the power consumption of a single stage double acting air compressor gives the following particulars. Cylinder diameter – 280 mm, stroke – 200 mm, clearance volume – 1 bar, speed – 350 rpm. The compression and expansion index – 1.3. 13. Find the percentage saving in work by compressing air in two stages from one bar to seven bar instead of in one stage. Assume compression index 1.35 in both cases and complete intercooling in two-stage compressor. 14. Obtain an expression for the minimum work required for a two-stage reciprocating air compressor. 3 15. A two-stage air compressor delivers 145 m of free air per hour the pressure and temperature in the cylinder at the start of compressor are 1 bar and 307 K respectively. The diameter of the low-pressure cylinder is twice that of high-pressure cylinder. The air enters in the high-pressure cylinder at a temperature of 313 K and is 1.22 then compressed to 17.5 bar the law of compression begins p.V = C for the both the stage. Neglect the effect of clearance. Estimate 1. The intercooler pressure 2. Power required, 3. The ratio of cylinder diameter for the maximum work.

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16. Determine the size of a double acting air compressor of Ip 22.07 KW in which the air is draw in at 1.05 bar and compressed to 6.3 bar with compression index as 1.2. The compressor runs at 100 rpm. The average piston speed may be taken as 120 m/ min. 17. Find the percentage saving in work by compressing air in three stages from 1 bar to 7 bar instated of in one stage. Assume compression index 1.35 in both cases and complete inter cooling in stage compressor. 18. The Following details are obtained from a two stroke single acting compressor: capacity – 4.5 mm at S.T.P. o delivery pressure – 12 bar; suction – 0.9 bar and 25 C; index of compression and expansion – 1.25; speed – 150 rpm; clearance volume – 5% of stroke volume. Assume cooling perfect and minimum work required and stroke = diameter. Find IP and diameter of cylinder. 3 19. A cylinder reciprocating air compressor has a displacement of 0.15 m . The suction condition of air is 1 bar o and 15 C. The air after compression to 8 bar is delivered to a receiver at constant pressure. The compression takes place adiabatically and gamma – 1.4. Determine 1. The temperature at the end of compression; 2. Work done by air during suction; 3. Work done on air during delivery and 4. Network done on air per cycle. Take R = 0.287 Kj/KgK. 20. Estimate the dimensions of the cylinder required for a single acting compressor of indicated power 10.3 KW 1.2 which is working as a single compressor. The law of compression is p.V = C, the upper and lower pressure 2 2 limits being 770 KN/m and 110 KN/m respectively. The compressor runs at 240 rpm and the average piston speed may be taken as 150 - m/min. Neglect the effect of clearance volume. o 21. A two-stage compressor works between 1 bar and 16 bar. The inlet temperature is 30 C. Determine the exit temperature, if intercooling is perfect and compression is isentropically. Also find the work done per kg. Of air with and without intercooling. 2 22. A two stage, single acting reciprocating compressor takes in air at the rate of 0.2 m /s. intakes pressure and 2 o 2 temperature are 0.1 MN/m and 16 C. The air is compressed to a final pressure of 0.7 MN/m . The intermediate pressure is ideal and intercooling is perfect. The compression index is 1.25 and the compressor runs at 10 rev/seconds. Neglecting clearance, determine 1. The intermediate pressure. 2. The total volume of each cylinder and 3. The cycle power. 3 23. A single stage, single acting reciprocating compressor runs at 120 rpm and delivers 6 m of free air per minute compressed to a pressure of 6.5 Kpa. The suction condition is 1 bar and 298 K. Index of compression and expansion is 1.25. Clearance is 5% of the stroke. Calculate 1. The temperature of air admitted to the receiver. 2. Volumetric efficiency. 3. Volume of air taken in per stroke. 4. Dimensions of the cylinder, if stroke is equal to 1.2 times the diameter and 5. Power required to deliver the compressor. 3 o 24. A stroke single acting reciprocating air compressor takes in 15m /min of air at 1 bar and 18 C. The air is compressed to 7.5 bar. The intermediate pressure is ideal and intercooling is perfect., the compression 1.3 follows the law p.V = C. and the compressor runs at 12 rpm. Neglecting clearance, determine 1. The intermediate pressure. 2. The total volume of each cylinder. 3. The cylinder power. 25. A single acting air compressor has a bore and stroke of both 100 mm and runs at 350 rpm. The clearance 5 2 volume is 75 cc and the index of compression and expansion is 1.23. The suction pressure is 0.95 X 10 N/m 5 2 5 2 o and the delivery is 7 X 10 N/m . Calculate the volume of free air at 10 N/m and 20 C delta with per minute. o If the temperature at the start of compression is 30 C.

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MODEL QUESTION PAPER CODE NO: ### TIME: 3 HRS

MAX.MARKS: 75

Note: Answer all the questions choosing any TWO divisions from (a) and any ONE from (b) of each question.

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a) 1. Define the term system, surrounding and boundaries. 2. State the first and second law of thermodynamics. 3. Define 1. Closed cycle, 2. Open cycle, and 3. Isolated cycle. o

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b) 1. Air at 1 bar and 40 C is compressed isentropically to 1/10 of the original volume. Determine the (7) Following per kg of air 1. Work done. 2. Change in enthalpy. 3. Change in entropy. 4. Change In Internal energy. Assume R = 287 KJ/KgK. And gamma = 1.41. 5 2 5 2 2. 2 Kg of gas at 8X10 N/m expands adiabatically till the pressure falls to 4X10 N/m . During the (7) 0 o Process 1,20,000 Nm of work is done by the system and the temperature falls from 377 C to 257 C Calculate the value of index of expansion and characteristic gas constant. II

a) 1. Write down the applications of steady flow energy flow equation. 2. What is meant by reversible cycle? State the conditions for reversibility. 3. Sketch the p-V and T-S diagram for petrol and diesel cycle. b) 1. Derive an expression for the air standard efficiency of an Otto cycle. 1.25 2. An indicated diagram taken on a diesel engine shows the compression curve follows pV = C. th th The pressure at two points lying on the compression curve at 1/8 and 7/8 of the stroke are 1.6 bar and 16 bar. Find the compression ratio of the engine. If the cut off occurs at 6% of the stroke. Calculate the air standard efficiency.

III a) 1. Explain the term “ Scavenging”. 2. What are the functions of lubrication in IC engines? 3. What is meant by supercharging? What is the effect of supercharging In an IC engines? b) 1. Explain with neat sketch the electronic ignition system. 2. Briefly, describe various methods of governing employed in IC engines. IV a) 1. What is meant by excess air? Explain the significant of excess air. 2. Define 1. Indicated power, 2. Brake power, 3. Mechanical efficiency, and 4. Relative efficiency. 3. What is calorific value of the fuel? What is the difference between HCV and LCV?

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b) 1. A fuel oil consists of the following percentage analysis by mass. 82% C, 12% H2, 2% O2, 1% S, and 3% N2. Determine stoichiometric mass of air required to completely burn the fuel and also Determine the products of combustion by mass as percentage. 2. A six cylinder four stroke engine had a bore to stroke ratio 360:500 mm. During the trial, following 2 Results were obtained. 1. Mean area of indicator diagram – 0.00075 m . 2. Length of indicated 2 Diagram. – 0.075 m 3. Spring number – 70,000 KN/m per m of compression. 4. Brake torque – 14 KNm. 5. Speed – 500 rpm. 6. Fuel consumption – 240 kg/ hr. calculate 1. Indicated power, 2. Brake power, 3. Mechanical efficiency. 4. Specific fuel consumption.

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a) 1. Compare reciprocating compressor and rotary compressor. 2. How air compressors are classified. 3. Compare open cycle gas turbine and closed type gas turbine.

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b) 1. Explain the working of ram jet engine with neat sketch. 2. Determine the size of a double acting air compressor of IP 22.07 KW in which the air is drawn in at 1.05 bar and is compressed to 6.3 bar with compression index as 1.2. The compressor runs at 100 rpm. The average piston speed may be taken s 120 m / min.

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