University: Annamalai University
Course: THERMODYNAMICS
Subject : ENGINEERING THERMODYNAMICS
Year of Question Paper : June 2012
Answer ALL questions
Course: THERMODYNAMICS
Subject : ENGINEERING THERMODYNAMICS
Year of Question Paper : June 2012
Reg. No. ________
Karunya University
(Karunya Institute of
Technology and Sciences)
(Declared as Deemed to be University under Sec.3 of
the UGC Act, 1956)
Supplementary Examination – June
2012
Subject Title: ENGINEERING THERMODYNAMICS
Time: 3 hours
Time: 3 hours
Subject Code:09ME202
Maximum Marks: 100
Maximum Marks: 100
Answer ALL questions
PART – A (10 x 1 = 10 MARKS)
1. A
system consisting of single phase is called _______.
2. Does
heat transfer inevitably cause a temperature rise?
3. What
are the four processes that constitute Carnot cycle?
4. Can
we use same plant as a heat pump in a winter and as refrigeration in summer?
5. Entropy
of pure substance is equal to _______.
6. Write
Vander wall’s equation of gases.
7. What
is the compressibility factor?
8. What
is meant by perpetual motion machine of first kind?
9. Brayton
cycle consist of two _______ process and two _______ process.
10. Write
the equation to determine air standard efficiency of an engine working in Otto
cycle.
PART – B (5 x 3 = 15 MARKS)
11. Define
thermodynamic system.
12. State
the Carnot theorem.
13. What
are intensive property and extensive property?
14. State
the Avagadro’s law.
15. Draw
the p-v and t-s diagram of Brayton cycle.
PART – C (5 x 15 = 75 MARKS)
16. In a gas
turbine the gas enters at the rate of 5 kg/s with a velocity of 50 m/s and
enthalpy of 900 kJ/kg and leaves the turbine with a velocity of 150 m/s and
enthalpy of 400 kJ/kg. The loss of heat from the gases to the surrounding is 25
kJ/kg. Assume for gas R=0.285 kJ/kgK and Cp=1.004kJ/kg K and the
conditions to be at 100 kPa and 27°C.
Determine the power output of the turbine and the diameter of the inlet pipe.
(OR)
17. a. Define point function and path
function. (5)
b. Describe about Macroscopic and
Microscopic approach. (5)
c. Explain briefly - Quasi – Static
process. (5)
18. A
reversible heat engine operates two reservoirs at temperatures of 600°C and 40°C.
The engine drives a reversible refrigerator which operates between reservoirs
at temperatures of 40° C and -20° C. The heat transfer to the heat engine is
2000 kJ and the net work output of the combined engine refrigerator plant is
360 kJ.
a. Evaluate the heat transfer to the refrigerant
and the net heat transfer to the
reservoir at 40C
b. Reconsider (a) given that the efficiency of
the heat engine and the COP of the refrigerator are each 40% of their maximum possible values.
(OR)
19. a. Derive the equation of the in quality
of Clausius. (10)
b. State: Kelvin and Clausius statement of
Second law of thermodynamics. (5)
[P.T.O]
20. Steam
initially at 0.3 MPa, 250° C is cooled at constant volume.
a. At what temperature will the steam become
saturated vapour?
b. What is the quality at 80° C?
c. What is the heat transferred per kg of
steam in cooling from 250° C to 80° C?
(OR)
21. a. The following data refer to a 12 – cylinder,
single acting, two stroke marine diesel engine: Speed – 150 rpm, Cylinder diameter – 0.8m, Stroke of
piston – 1.2m, Area of indicator diagram
– 5.5 x 10 -4 m2. Length of diagram – 0.06 m, spring
value – 147 MPa/m. Find the net
rate of work transfer from the gas to the pistons in kW. (10)
b. Draw the P-T and PV diagrams for pure
substances. (5)
22. A mass of
air is initially at 260 C and 700 kPa and occupies 0.028 m3. The air
is expanded at constant pressure to 0.084 m3. A polytropic process
with n=1.5 is then carried out, followed by a constant temperature process
which completes a cycle. All the processes are reversible. Sketch the cycle in
PV and TS planes and find the heat received and heat rejected in the cycle.
Also find the efficiency of the cycle.
(OR)
23. Derive the
expression for the following: Specific heat, Internal Energy and Enthalpy for
an ideal gas.
24. In an air
standard cycle, the compression ratio is 16, Temperature is 15° C and pressure
is 0.1 MPa. Heat is added until the temperature at the end of the constant
pressure process is 1480°C. Calculate (a) The cut-off ratio, (b) the heat
supplied per kg of air, (c) The cycle efficiency and (d) the m.e.p.
(OR)
25. In a gas
turbine plant, working on the Brayton cycle with a regenerator of 75%
effectiveness, the air at the inlet to the compressor is at 0.1 Mpa., 30° C,
pressure ratio is 6 and the maximum cycle temperature is 900° C. If the turbine
and compressor have each an efficiency of 80 %, find the percentage increase in
the cycle efficiency due to regeneration.
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