THE RAJAAS ENGINEERING
COLLEGE
Vadakkangulam –
627116.
DEPARTMENT OF
MECHANICAL ENGINEERING
INTERNAL TEST -1
ME
33 ENGINEERING THERMODYNAMICS
YEAR /SEM : II/III Max.
Marks : 50
Date :01-09-‘10 Time
: 2 hours.
Part A
ANSWER ALL
QUESTIONS (5
X 2 = 10)
- Define Zeroth law and first law of thermodynamics.
- Define intensive properties and extensive properties.
- What is meant by path and point functions?
- Define the term enthalpy.
- Sketch isothermal expansion on P-V diagram and state the properties that remains constant.
ANSWER ALL
QUESTIONS
6. A mass of air is initially at 260o C and 700
KPa and occupies 0.028m3. The air is expanded at constant pressure
to 0.084 m3. A polytrophic process with n=1.5 is then carried out,
followed by a constant temperature process. All the process are reversible.
a) Sketch
the cycle in the P-V and T-S planes.
b) Find the
heat received and heat rejected in the cycle.
c) Find the
efficiency of the cycle. (16)
7. A gas flows steadily through compressor. The gas enters
the compressor at a temperature of 16oC, A pressure of 100KPa, and
an enthalpy of 391.2 KJ/Kg. The gas leaves the compressor at a temperature of
245oC, a pressure of 0.6MPa, and an enthalpy of 534.5KJ/Kg. There is
no heat transfer to or from the gas as it flows through the compressor.
Evaluate the external work done per unit mass of gas when the velocity at the
entry is 80 m/s and that at exit is 160m/s. (8)
8. Two Carnot engines A and B are operated in series. The
first one (A) receives heat at 870 K and rejects to reservoir at temperature T.
The second engine (B) receives the heat rejected by the first engine and in
turn rejects to a heat reservoir at 300 K. Calculate the intermediate
temperature T in o C between two heat engines for the following
cases.
a) The work
output of the two engines are equal and
b) The
efficiency of the two engines are equal. (16)
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