Engineering :: Thermodynamics
61.
The efficiency of a Rankine cycle may be expected to
A.
Increase with decreasing temperature of heat rejection
B.
Decrease with decreasing temperature of heat rejection
C.
Decrease with increasing temperature of heat rejection
D.
Increase with increasing exhaust pressure
E.
None of the above
Answer: Option A
Explanation:
62.
A Rankine cycle working with saturated steam differs thermodynamically from a Carnot cycle only in the fact that
A.
The Carnot cycle cannot be used for vapour
B.
Steam is not the working substance for Carnot cycle
C.
There are more than two sources of heat in Rankine cycle
D.
Heat is supplied to the water at temperatures below the maximum temperature of the cycle
E.
None of the above
Answer: Option D
Explanation:
63.
Rankine cycle efficiency for a power plant is 29.6%. The Carnot cycle efficiency will be
A.
Equal to Rankine cycle efficiency
B.
More than Rankine cycle efficiency
C.
Less than Rankine cycle efficiency
D.
There is no comparison for the two
E.
None of the above
Answer: Option B
Explanation:
64.
Triple point
A.
Occurs in sublimation
B.
Occurs in a mixture of two or more gases
C.
Is the range of temperature within which three constituents simultaneously change phase
D.
Is that point where three phases solid, liquid and gas exist together
E.
None of the above
Answer: Option D
Explanation:
65.
The triple point for carbondioxide is at about -56.7 C and about 5 atm, pressure. It means that
A.
When solid CO2 is exposed to 1 atm pressure it begins to change directly to gas
B.
When CO2 is exposed to a below 5 atmosphere pressure only solid and liquid phase exist together
C.
Below 57.7 C CO2 exists only in liquid form
D.
Above 56.7 C CO2 exists only as a liquid
E.
Mass transfer at triple point is maximum
Answer: Option A
Explanation:
66.
When a fluid is passed in steady, flow through a porous plug in a duct under such conditions that heat transfer, kinetic energy change and potential change is negligible, the process is called
A.
Constant pressure compression
B.
Isothermal compression
C.
Frictionless compression
D.
Throttling
E.
Separation
Answer: Option D
Explanation:
67.
During throttling process
A.
Internal energy does not change
B.
Pressure does not change
C.
Entropy does not change
D.
Enthalpy does not change
E.
Volume change is negligible
Answer: Option D
Explanation:
68.
If the dryness fraction of a sample by throttling calorimeter is 0.8 and that by separating calorimeter is also 0.8, then the actual dryness fraction of sample will be taken as
Answer: Option C
Explanation:
69.
When a gas is to be stored, the type of compression that would be ideal is
A.
Isothermal
B.
Adiabatic
C.
Polytropic
D.
Constant volume
E.
None of the above
Answer: Option A
Explanation:
70.
The adiabatic horse power required to deliver 4 cu. M per minute of free air from 1 ata and 15?C to a received pressure at 7 ata would be in the range
A.
5 ? 7
B.
7 ? 10
C.
10 ? 15
D.
15 ? 20
E.
20 ? 25
Answer: Option E
Explanation:
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