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DIPLOMA ENGINEERING – SEMESTER –III EXAMINATION – WINTER 2014
Subject Code: 3331902 Date: 29/11/2014
Subject Name: Thermodynamics
Time: 10:30 am – 1:00 pm Total Marks: 70
Instructions:
1. Attempt any five questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Each question carry equal marks (14 marks)
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Q.1 (a) Explain Quasi-static process with neat sketch and diagram. 07
(b) (1) Define energy. Write the similarities and differences of heat energy and work energy.
(2) Explain Avogadro’s law. 04
Q.2 (a) In gas turbine mass flow rate of gas is 5Kg/s. The velocity of air at entrance is 200m/s and
its enthalpy is 6600 KJ/Kg. The velocity of outgoing gas is 150m/s and its enthalpy is 5500KJ/Kg. Heat rejected from the system to surrounding is 50KJ/Kg. Determine power developed by the
turbine. 07
(b) Explain control mass and control volume. Explain application of SFEE. 07
OR
(b) Explain how first law of thermodynamics is applied to Boiler & turbine to
energy transfer. 07
Q.3 (a) For an adiabatic process prove that pvĪ³ = constant. 07
(b) In a gas turbine expansion of the gas take place from 10 bar pressure to 1 bar
pressure. During the expansion change in volume is from 2m3 to 8m3.Find out
value of polytropic index n and workdone of the process. 07
OR
Q.3 (a) Draw and explain polytropic and isothermal process on P-V and T- S diagram. 07
(b) 0.1 m3 of air at a pressure of 1.5 bar is expanded isothermally to 0.5m3.
Calculate the final pressure of the gas and heat supplied during process. 07
Q.4 (a) Explain Kelvin plank statement. Prove equivalence between Kelvin plank and
Clausius statement. 07
(b) Explain International Practical Temperature Scale. 07
OR
Q. 4 (a) What is Entropy ? Explain its importance in thermodynamics. 07
(b) Explain the C.O.P of refrigerator, Heat pump and thermal efficiency of heat engine. 07
Q.5 (a) Derive the expression of air standard efficiency of otto cycle. 07
(b) An engine working on otto cycle is supplied with air at 0.1 Mpa,300c the compression ratio is 5. Heat supplied is 2000 KJ/Kg. Calculate the maximum pressure,temperature of the cycle and the
cycle efficiency. Take Cp =1.005KJ/Kg K,Cv = 0.718 KJ/Kg K, R = 0.287 KJ/Kg K. 07
OR
Q.5 (a) Derive the expression of air standard efficiency of Dual cycle. 07
(b) In Diesel cycle the compression ratio is 16, pressure and temperature in begining of the compression stroke are 1 bar & 20 0C respectively and the maximum temperature of the cycle is 1430 0C. Find the thermal efficiency of cycle. 07
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