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Diploma Engineering - SEMESTER–III • EXAMINATION – WINTER 2013
Subject Code: 3331902 Date: 30-11-2013
Subject Name: Thermodynamics
Time: 02:30 pm - 05:00 pm Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. English version is considered to be Authentic.
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Q.1 (a) State the Zeroth law of thermodynamics and its application. Name various
Temperature measurement devices used with related unit. 07
(b) Differentiate followings
(1) Heat and Work. 03
(2) Extensive properties and Intensive properties. 02
(3) Thermodynamic cycle and Mechanical cycle. 02
Q.2 (a) State first law of thermodynamics and prove internal energy is a property. 07
(b) Which are the conditions for steady flow? Derive SFEE for open system. 07
OR
(b) State both statement of second law of thermodynamics. Also show their
equivalence with neat sketch. 07
Q.3 (a) A heat engine receives energy of 2000 kJ/min and doing work of 1500 kJ/min.
Find out thermal efficiency and heat rejection rate. 07
(b) Derive characteristic of gas equation using an ideal gas laws. 07
OR
Q.3 (a) 2 kg of gas enclosed in a closed vessel has absolute pressure 2 bar and temperature 27 °C. If it is compressed up to 6 bar pressure find Temperature and change in internal energy.
Take Cp=1.005 kJ/kg K, R = 0.287 kJ/kg K. 07
(b) Draw P-V and T-ϕ diagram for Isothermal process and derive equation of
work and heat for Isothermal process. 07
Q.4 (a) Show following process on P-V and T-S plane
(1) Constant volume Process (2) Isothermal Process.
(3) Isentropic Process (4) Isobaric Process. 07
(b) Derive equation of C.O.P. for reversed Brayton cycle for refrigeration purpose. 07
OR
Q. 4 (a) Explain the term Entropy. Discuss the practical significance of entropy. 07
(b) A Compression Ignition Engine working between 60 °C and 800 °C. What
could be the maximum efficiency of the cycle? 07
Q.5 (a) Explain following
1. Concept of Air standard efficiency. 03
2. Name the methods of measuring dryness fraction of steam. 04
(b) In a refrigerator working on reverse Brayton cycle, air is compressed from 10°C and 1 bar pressure to 5 bar pressure. After compression air is cooled down to 20 °C in air cooler,
Find (1) C.O.P. (2) work required. Take Cp = 1.005 kJ/kg K, Cv = 0.718 kJ/kg K. 07
OR
Q.5 (a) Define followings : (1) Wet steam (2) Dry and Saturated steam (3) Sensible heat
(4) Triple point (5) Degree of super heat (6) Dryness fraction steam (7) Latent heat. 07
(b) Determine the enthalpy, entropy and volume for 5 kg of steam having 12 bar
pressure and 0.85 dryness fraction. 07
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