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edu.subha.peperonity.net

MOCK CLASS TEST: THERMODYNAMICS

Sub: Code: EME-303; Mahamaya Technical University

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Time: 2 hrs ....... Maximum Marks: 50

Attempt all the questions:

SECTION A:

1) Attempt the following questions: (5 x 2 = 10)

a) Define system, surroundings and universe.

b) Distinguish between Heat pump and Refrigerator.

c) What is Exergy and Anergy?

d) Explain the law of degradation of energy.

e) What is triple point of water?

SECTION B:

2) Attempt any three questions: (3 x 5 = 15)

a) Distinguish between macroscopic and microscopic approaches of thermodynamics.

b) Discuss the neccessity of 2nd law of thermodynamics.

c) 2 kg of a gas at 10 bar expands adiabatically and reversibly till its pressure drops to 5 bar. During the process 120 kJ of non-flow work is done by the system and the temperature drops from 377 centrigrade to 257C. Calculate the value of the index of expansion and the characteristics gas constants.

d) Steam at a pressure of 4 bar absolute and having dryness fraction 0.8, is heated at constant volume to a pressure of 8 bar absolute. Find the final temperature of the steam. Also, find the total heat absorbed by 1 kg of steam.

e) 2 kg of air at NTP is heated at constant volume untill the pressure becomes 6 bar. Find the change of entropy of the system.

SECTION C:

Attempt part (a) or part (b) of the following questions (5 x 5 = 25)

3) (a) Explain the thermodynamic equilibrium and quasi-static process.
(b) Prove the equivalence of Kelvin-Planck statement and Clausius statement.

4) (a) A steam turbine developing 110 kW is supplied steam at 17.5 bar with an internal energy of 2600 kJ/min, specific volume = 15.5 m3/kg and velocity of 275 m/s. Heat loss from the steam turbine i7 37.6 kJ/kg. Neglecting the changes in potential energy, determine the steam flow rate in kg/hr.

(b) A reversible engine takes 2400 kJ/min from a reservoir at 750 K develops 400 kJ/min of work during cycle. The engine rejects heat at two reservoir at 650 K and 550 K. Find the heat rejected to each sink.

5) (a) Explain the causes of internal and external irreversibility.

(b) Explain the importance of Gibb's function and Gibb's free energy.

6) (a) 5 kg steam at pressure 8 bar and temperature 300 C is adiabatically mixed with 4 kg steam at 6 bar and 250 C. Find the final condition of the mixture. Also find the change in entropy.

(b) Hot steam is flowing through a perfectly adiabatic pipe. At point A the temperature of the steam is 250 C and pressure is 4 bar, while at the point B, its temperature is 275 C and pressure is 3.5 bar. Find the direction of the flow.

7) (a) 5 kg of Oxygen is enclosed within a vessel of 0.05 m3 at a temperature 200 C, is being supplied 120 kJ of energy through heating. Find the final pressure and temperature.

(b) One kg of an ideal gas is heated from 18.3 C to 93.4 C. Assuming R = 287 J/kg-K and gama = 1.18 for the gas. Find out (i) specific heats,
(ii) change in internal energy,
and (iii) change in enthalpy and entropy.


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