College : Vardhaman College Of Engineering
Degree : B.Tech
Department : Aeronautical Engineering
Semester : III
Subject :Thermodynamics
Document type : Question Paper
Website : vardhaman.org
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Thermodynamics Question Paper :
B. Tech III Semester Regular Examinations, December – 2013
(Regulations : VCE-R11)
Date : 4 December, 2013
Time : 3 Hours
Max. Marks : 75
Answer ONE question from each Unit
All Questions Carry Equal Marks
All parts of the question must be answered in one place only
Related : Vardhaman College Of Engineering Elements Of Electrical Engineering B.Tech Question Paper : www.pdfquestion.in/6308.html
Unit – 1 :
1. a) Distinguish between
i. Intensive and extensive properties
ii. Thermal equilibrium and Mechanical equilibrium
iii. Adiabatic wall and a dia-thermal wall 7M
b) An engine cylinder has a piston of area 0.12m2and contains gas at a pressure of 1.5 MPa. The gas expands according to a process which is represented by a straight line on a pressure volume diagram. The final pressure is 0.15MPa. Calculate the work done by the gas on the piston if the piston stroke is 0.30m. 8M
2. a) Give the precise statement of first law of thermodynamics as applied in a closed system undergoing a process and hence prove that internal energy is a property. 7M
b) 1.5 kg of gas undergoes a quasi-static process in which the pressure and specific volume are related by the equation p = a+ bv, where a and b are constants. The initial and final pressures are 1000 kPa and 200 kPa respectively. The corresponding volumes are 0.2 m3 and 1.2 m3. The specific internal energy of the gas is given by the relation u=1.5 pv-35 where u is in kJ/kg, p is in kPa and v is in m3/kg. Find the magnitude and direction of heat transfer and the maximum internal energy of the gas during the process. 8M
Unit – 2 :
3. a) What is a heat engine? If all heat engines are operated between same temperature levels then show that the efficiency of reversible heat engines is more than the irreversible heat engines. 8M
b) A car not engine operates between T1 and T2 K. Work output of engine is 0.6 times heat rejected. Given that the difference in temperature between source and sink as 2000C find
i. Source temperature
ii. Sink temperature
iii. Engine efficiency 7M
4. a) Represent the car not heat engine cycle on PV and TS diagrams and explain briefly 7M
b) Prove that whenever a system executes a complete cyclic process the quantity 8M
Unit – 3 :
5. a) Define the following which refers to water
i. Dryness fraction
ii. Enthalpy of superheated steam
iii. Latent heat 6M
b) The following observations were taken with a separating and a throttling calorimeter arranged in series. Water separated=2 kg, steam discharged from the throttling calorimeter=20.5 kg, temperature of steam after throttling=1100C, initial pressure=12 bar abs. barometer reading=760 mm of Hg, final pressure=5 mm of Hg. Estimate the quality of steam supplied. 9M
6. a) Explain
i. Law of corresponding states
ii. Compressibility chart 7M
b) A vessel of 2.75 m3 capacity contains 5 kg of oxygen at 300 K. Determine the pressure exerted by oxygen using Vander Waal’s equation. Compare the result obtained if oxygen is treated as ideal gas .The constants appearing in the Vander Waal’s equation having the values: = 139.35 * 103 N m4 /( kg mol) 2 and b = 0.0314 m3/kg mol. 8M
Unit – 4 :
7. a) i. Define the terms partial pressure, mole fraction, volume fraction of a gas constituent in a mixture 8M
ii. State Dalton’s law of partial pressure and derive an expression for the gas constant of a mixture of ideal gases.
b) A gas mixture consists of 6 Kmol of H2 and 4 Kmol of N2. Determine the mass of each gas and the gas constant of the mixture. 7M
8. a) What is meant by mass, volume and mole fractions? 7M
b)A mixture of hydrogen (H2) and oxygen (O2) is to be made so that the ratio of H2 to O2 is 2:1 by volume. If the pressure and temperature are 1 bar and 250C respectively, calculate
i. The mass of O2 required
ii. The volume of container 8M
Unit – 5 :
9. a) Derive an expression for the thermal efficiency of an air standard Otto cycle. State the assumptions made. 8M
b) The following particulars refer to four stroke diesel engine cycle.
Compression ratio 21:1 and expansion ratio 10.5:1
Determine the cut off ratio and air standard efficiency 7M
10. a) Derive an expression for thermal efficiency of air standard Diesel cycle in terms of compression ratio, cut off ratio and the adiabatic index. 8M
b) Otto cycle is designed to operate with the following data: Maximum cycle pressure and temperature -5 Mpa and 2250K Minimum cycle pressure and temperature -0.1 Mpa and 300K Determine network output per unit mass of working find and thermal efficiency Take CV=0.718 KJ/kg K 7M