ME 2202 ENGINEERING THERMODYNAMICS SECOND UNIT EXAMINATION

B.E./B.TECH.DEGREE SECOND UNIT EXAMINATIONS, AUGUST - 2012

REGULATIONS 2008

SECOND YEAR / THIRD SEMESTER

ME 2202 ENGINEERING THERMODYNAMICS

MECHANICAL ENGINEERING

Time: 90 MINUTES                           Date:   08.08.2012                              Maximum:50 marks

ANSWER ALL QUESTIONS

                                                                  PART – A                        (9 x 2 =18 marks)

1.     What is meant by reversible and irreversible process?

2.     Explain Zeroth Law and first law of thermodynamics?

3.     What are the limitations of first law of thermodynamics?

4.     Define available energy and unavailable energy.

5.     What are the important characteristics of entropy?

6.     Define the term enthalpy and entropy

7.     What is perpetual motion machine of first kind and second kind?

8.     State the Kelvin – Plank and Clausius statement of second law of thermodynamics

9.     State Carnot’s theorem. What are the Corollaries of Carnot theorem?

                                                      PART – B                       (2 x 16 =32 marks)

ANSWER ANY TWO QUESTIONS

1.     Air at a temperature of 15⁰ C passes through a heat exchanger at a velocity of 30 m/s where its temperature is raised to 800⁰ C. It then enters a turbine with the same velocity of 30 m/s and expands until the temperature falls to 650⁰ C. On leaving the turbine, the air is taken at a velocity of 60 m/s to a nozzle where it expands until the temperature has fallen to 500⁰ C. If the air flow rate is 2 kg/s, calculate :

          (i) The rate of heat transfer to the air in the heat exchanger.

          (ii) The power output from the turbine assuming no heat loss and

          (iii) The velocity at exit from the nozzle, assuming no heat loss.

Take the enthalpy of air as h = Cp.T, where Cp is the specific heat equal to 1.005 kJ/kg–K and ‘‘T’’ the temperature.

2.     A reversible heat engine operated between temperatures 800^oC and 500^oC of thermal reservoirs. Engine drives ‘a generator’ and ‘a reversed Carnot engine’ using the work output from the heat engine for each unit equality. Reserved Carnot engine abstracts heat from 773 K reservoir and rejects that to a thermal reservoir at 715^oC. Determine the heat rejected to the reservoir by the reserved engine as a fraction of heat supplied from 800^oC reservoir to the heat engine. Also determine the het rejected per hour for the generator output of 300 kW.

3.     Derive the maximum work obtainable from two finite bodies and also determine the maximum work obtainable using one finite body and a thermal Reservoir.