Anna University Chennai 2007-2nd Sem B.Tech II Supplimentary s, / - Question Paper

Code No: R05222103 Set No. 1
II B.Tech II Semester Supplimentary Examinations, Aug/Sep 2007
THERMODYNAMICS
(Aeronautical Engineering)
Time: three hours Max Marks: 80
ans any 5 ques.
All ques. carry equal marks
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1. A uid contained in a horizontal cylinder fitted with a frictionless leak proof piston,
is continuously agitated by means of a stirrer passing through the cylinder cover.
The cylinder diameter is 0.4 m. During the stirring process lasting 10 minutes, the
piston slowly moves out a distance of 0.485 m against the atmosphere. The net
work done by the uid during the process is two kJ. The speed of the electric motor
driving the stirrer is 840 rpm. Determine torque in the shaft and power output of
the motor. [16]
2. (a) State the zeroth legal regulations of thermodynamics. discuss how it forms the basis for
temperature measurement?
(b) A closed system undergoes a thermodynamic cycle consisting of 4 separate
and distinct processes. The heat and work transferred in every process are as
tabulated beneath.
Process Heat Transfer in KJ/min Work transfer in KJ/min
1-2 20,000 0
2-3 -10,000 30,000
3-4 0 20,000
4-1 15,000 -25,000
Show that the data is consistent with the 1st legal regulations of thermodynamics. Also evaluate
the net work output in KW and the change in internal energy. [6+10]
3. (a) describe thermal efficiency of a heat engine. Can it be 100 percent?
(b) A reversible heat engine receives heat from 2 thermal reservoirs at 870 K
and 580 K, and rejects 50 KW of heat to a sink at 290 K. If the engine output
is 85 KW, make computations for the engine efficiency and heat supplied by
every reservoir. [6+10]
4. (a) define the process of formation of steam and provide its graphical representation
(b) Steam enters an engine at a pressure 10 bar absolute and 250
0
C. It is exhausted
at 0.2 bar. The steam at exhaust is 0.9 dry. obtain
i. Drop in enthalpy
ii. change in enthalpy. [7+9]
5. one kg of air at 1.2 bar pressure and 18
0
C is compressed isentropic ally to seven bars.
obtain the final temperature and the work done. If the air is cooled at the upper
pressure to the original temperature of 18
C ,what amount of heat is rejected and
what further work of compression is done. [16]
6. (a) discuss
i. Heating and dehumidification
ii. Cooling and dehumidification
(b) A Room of dimensions 6mX 3mX 3m contains an air water vapour mixture
at one bar 30
0
C and 70 % Relative humidity. compute
i. Mass of air
ii. Mass of water vapour
iii. Degree of saturation [10+6]
7. (a) What is a cycle? What is the difference ranging from an ideal and true cycle.
(b) Derive an expression for efficiency of Brayton cycle in terms of pressure ratio.
[8+8]
8. (a) discuss the 4 processes make up the simple ideal Rankine cycle. How do
true vapor cycles differ from the idealized ones(with the help of P-V, T-S
charts)?
(b) explain the essential properties of refreigerants. [10+6]
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Earning:   Approval pending.