Thermodynamics Questions and Answers – Reversed Heat Engine

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This set of Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on “Reversed Heat Engine”.

1. Refrigeration is the cooling of any system below its surroundings temperature.
a) true
b) false
View Answer

Answer: a
Explanation: 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
View Answer

Answer: b
Explanation: 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
View Answer

Answer: d
Explanation: This is the basic working of reversed heat engine.
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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
View Answer

Answer: c
Explanation: 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)
View Answer

Answer: a
Explanation: 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)
View Answer

Answer: b
Explanation: 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
View Answer

Answer: a
Explanation: A refrigerant is referred particularly to a refrigeration cycle.
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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
View Answer

Answer: d
Explanation: 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)
View Answer

Answer: a
Explanation: For a heat pump, COP = Q1/W = T1/(T1-T2).
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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)
View Answer

Answer: b
Explanation: 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
View Answer

Answer: b
Explanation: This means, closer the temperatures T1 and T2, the higher is the COP.

Sanfoundry Global Education & Learning Series – Thermodynamics.
To practice all areas of Thermodynamics, here is complete set of 1000+ Multiple Choice Questions and Answers.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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