1. Roll No.
B.E / B.Tech ( Part-Time ) DEGREE END SEMESTER EXAMINATIONS, APRIL/ MAY 2014
PTME 8201 ENGINEERING THERMODYNAMICS
(Use of Steam tables, Mollier chart and Psychrometry chart permitted)
Time: 3 Hours Answer ALL Questions Max. Marks 100
PART- A (10 x 2 = 20 Marks)
1. What is the work transfer in free expansion process?
2. What is a PMM2?
3. What is a dead state? What is its significance?
4. What is irreversibility? and how it is related to the entropy of universe?
5. What is dryness fraction?
6. What are the methods for improving the performance of the Rankine cycle?
7. What are reduced properties?
8. What is Joule - Thomson coefficient? What does it signify?
9. What is Dalton's law of partial pressure?
10. What is sensible heating?
2. Part - B ( 5 x 16 = 80 marks)
11. A steam turbine under steady flow condition receives steam at a pressure of (16)
15 bar .internal energy of 2700 kJ/kg, specific volume of 0.17 m3
velocity of 100m/s. The exhaust of steam from the turbine is at a pressure of
0.1 bar, internal energy of 2175 kJ/kg, specific volume of 15m3
velocity 300m/s. The intake is 3 m above the exhaust. The turbine develops
35 kW and heat loss over the surface of the turbine is 20 kJ/kg. Determine
the required steam flow rate.
12 (a) Two Carnot refrigerators A and B operate in series. The refrigerator A (16)
absorbs energy at the rate of 1 kJ/s from a body at 300 K and rejects energy
as heat to a body at T. The refrigerator B absorbs same quantity of energy
which is rejected by the refrigerator A from the body at T, and rejects energy ^
as heat to a body at 1000 K. If both refrigerators have the same COP,
calculate: i) the temperature T of the body, ii ) The COP of the refrigerator
and iii) the rate at which energy is rejected as heat to the body at 1000 K.
(b) Air flows through an adiabatic compressor at 2 kg/s. The inlet conditions (16)
are 100 kPa and 310 K, and the exit conditions are 700 kPa and 560 K.
Consider T0 to be 298 K. Determine the change of availability and the
13 (a) A steam cylinder with piston contains steam at 8 bar and 435° C. If it is (16)
cooled to 200° C at constant pressure, calculate the heat and work transfer g
per kg and their direction.
(b) In a reheat Rankine cycle , steam enters the steam turbine at 30 bar and (16)
400 °C and expands in a high pressure steam turbine to an intermediate
pressure of 3 bar at which it is reheated to 400 °C, before entering the low
pressure turbine. The condenser pressure is 0.5 bar. If the mass flow rate of
steam is 40 kg/s, calculate the specific steam consumption, the net work per
kg, the power output and the thermal efficiency.
3. 14 (a) Nitrogen gas is stored at 175 K and 9500 kPa in a container. Calculate the (16)
specific volume of the gas if it is considered as i) ideal gas ii) van der Waals
gas and iii) the compressibility factor. Use the constants: a = 0.175 kPa.m
and b = 0.00138 m3
(b) (i) Derive any two of the Maxwell's relations. (8)
(ii) Prove that Joule - Thomson coefficient of an ideal gas is zero. (8)
^ 5 (a) A gas mixture consists of 65 kmol nitrogen and 35 kmol carbon dioxide. (16)
Calculate the mole fraction, mass fraction and molar mass.
(b) A stream of air at 1 atm pressure , 18 °C and 40 % relative humidity flowing (16)
at 550 m3
/h adiabatically mixes with another stream at 1 atm ,38 °C and 60
% relativity , flowing at 250 m3
/h to form a third stream at 1 atm pressure.
Determine the temperature, specific humidity, specific enthalpy and the
relative humidity of the mixed stream.