ME 2202 ENGINEERING THERMODYNAMICS FIRST UNIT EXAMINATION

B.E./B.TECH.DEGREE FIRST UNIT EXAMINATIONS, JULY - 2012

REGULATIONS 2008

SECOND YEAR / THIRD SEMESTER

ME 2202 ENGINEERING THERMODYNAMICS

MECHANICAL ENGINEERING

Time: Two Hours                                  Date:    .07.2012                               Maximum:50 marks

ANSWER ALL QUESTIONS

                                                                  PART – A                        (10 x 2 =20 marks)

1.      What is meant by Macroscopic approach and Microscopic approach in thermodynamics?

2.      What is meant by open system and closed system? Give an example.

3.      Explain homogeneous and heterogeneous system.

4.      What is meant by control volume and control surface?

5.      Differentiate Intensive and Extensive properties

6.      What is meant by thermodynamic equilibrium?

7.      Define continuum

8.      What is Quasi – Static process?

9.      What is meant by reversible and irreversible process?

10.  What is meant by point function and Path function?

                                                      PART – B                       (3 x 10 =30 marks)

11.  Derive the relationship between P-V-T, work done, change in internal energy , Heart transfer, change in enthalpy change in entropy and plot the P-V & T-S diagram for isentropic process.

12.  Air is contained in a cylinder fitted with a frictionless piston. Initially the cylinder contains  0.5m³ of air at 150 kPa, 20°C. The air is then compressed reversibly according to the relation  PVⁿ = constant, until the final pressure is 600 kPa, at which point the temperature is 120°C.  For this process, determine,

                        (i) The polytropic exponent n

                        (ii) The final volume of air

                        (iii) The work done on the air and the heat transfer and

                        (iv) The net change in entropy. 

13.  The inlet volume of 0.18kg of a certain gas was boiled 0.15m³. The temperature of 15⁰c and a pressure of 1 bar after adiabatic compression are    0.056 m³ the pressure was found to be 4 bar. Find the gas constant, molecular mass of gas, ratio of specific heat and change in internal energy.

14.  A mass of 1.5kg of air is compressed in a quasi static process from 0.1Mpa to 0.7 Mpa for which PV= constant. The initial density of air is 1.56kg/m³. Find the work done by the piston to the compressed air.

15.  A certain quantity of gas is heated at constant pressure from 35⁰c to 185⁰c. Estimate the amount of heat transferred, ideal work done, change in internal energy and change in entropy when the initial volume of the gas is 0.6m³. Assume R= 0.3 kj / kg.k. and Cp=1.005 kj/kg.k .

16.  A certain gas occupies a space 0.3m³ at a pressure of 2 bar and temperature 77⁰c. It is heated at constant volume untill the pressure is 7 bar. Determine temperature at the end of the process, mass of the gas, change in internal energy, change in enthalpy during this process. Assume Cp= 1.005  kj/kg.k, Cv=0.718 kj/kgk