250+ TOP MCQs on Reversed Heat Engine and Answers

Thermodynamics Multiple Choice Questions on “Reversed Heat Engine”.

1. Refrigeration is the cooling of any system below its surroundings temperature.
a) true
b) false
Answer: a
Clarification: This is what refrigeration means.

2. Dry ice is suitable for ____ temperature refrigeration.
a) high
b) low
c) all range of
d) none of the mentioned
Answer: b
Clarification: Dry ice when exposed to atmosphere sublimates by absorbing latent heat of sublimation.

3. A reversed heat engine
a) receives heat from a low temperature region
b) gives heat to a high temperature region
c) receives a net inflow of work
d) all of the mentioned
Answer: d
Clarification: This is the basic working of reversed heat engine.

4. Which of the following is a reversed heat engine cycle?
a) heat pump cycle
b) refrigeration cycle
c) both of the mentioned
d) none of the mentioned
Answer: c
Clarification: These are the reversed heat engine cycles.

5. For a heat pump, coefficient of performance is given by (Q1 is the heat taken from low temperature region and Q2 is the heat given to high temperature region)
a) Q1/(Q1-Q2)
b) Q2/(Q1-Q2)
c) 1- (Q1/Q2)
d) 1- (Q2/Q1)
Answer: a
Clarification: For a heat pump, COP = Q1/W = Q1/(Q1-Q2).

6. For a regenerator, coefficient of performance is given by (Q1 is the heat taken from low temperature region and Q2 is the heat given to high temperature region)
a) Q1/(Q1-Q2)
b) Q2/(Q1-Q2)
c) 1- (Q1/Q2)
d) 1- (Q2/Q1)
Answer: b
Clarification: For a heat pump, COP = Q2/W = Q2/(Q1-Q2).

7. The working fluid in a refrigeration cycle is known as refrigerant.
a) true
b) false
Answer: a
Clarification: A refrigerant is referred particularly to a refrigeration cycle.

8. Which of the following happens in a reversed Carnot cycle?
a) the refrigerant is compressed reversibly and adiabatically
b) it is condensed reversibly
c) it expands reversibly and adiabatically
d) all of the mentioned
Answer: d
Clarification: These processes take place in a reversed Carnot cycle.

9. For a heat pump, coefficient of performance is given by (T1 is the temperature of heat rejection and T2 is the temperature of heat absorption)
a) T1/(T1-T2)
b) T2/(T1-T2)
c) 1- (T1/T2)
d) 1- (T2/T1)
Answer: a
Clarification: For a heat pump, COP = Q1/W = T1/(T1-T2).

10. For a regenerator, coefficient of performance is given by (T1 is the temperature of heat rejection and T2 is the temperature of heat absorption)
a) T1/(T1-T2)
b) T2/(T1-T2)
c) 1- (T1/T2)
d) 1- (T2/T1)
Answer: b
Clarification: For a heat pump, COP = Q2/W = T2/(T1-T2).

11. For the same T1 and T2, COP increases with ____ in temperature difference.
a) increase
b) decrease
c) no change
d) none of the mentioned
Answer: b
Clarification: This means, closer the temperatures T1 and T2, the higher is the COP.