This set of Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on “Refrigerator and Heat Pump”.
1. Which device maintains a body at a temperature lower than the temperature of the surroundings?
a) PMM1
b) PMM2
c) refrigerator
d) heat pump
View Answer
Explanation: This is the main function of a refrigerator.
2. What does a refrigerant do?
a) absorbs the heat leakage into body from surroundings
b) evaporates in the evaporator
c) absorbs latent heat of vaporization form the body which is cooled
d) all of the mentioned
View Answer
Explanation: Refrigerant is required for the proper functioning of a refrigerator.
3. Coefficient of performance(COP) is defined as
a) heat leakage/work input
b) work input/heat leakage
c) latent heat of condensation/work input
d) work input/latent heat of condensation
View Answer
Explanation: Coefficient of performance is the performance parameter used in a refrigerator cycle.
4. Which device maintains a body at a temperature higher than the temperature of the surroundings?
a) PMM1
b) PMM2
c) refrigerator
d) heat pump
View Answer
Explanation: This is the main function of a heat pump.
5. In a heat pump, there is heat leakage from the body to the surroundings.
a) true
b) false
View Answer
Explanation: This is just opposite to a refrigerator.
6. What is the relation between COP of heat pump and refrigerator?
a) COP of pump=COP of refrigerator – 1
b) COP of pump=COP of refrigerator + 1
c) COP of pump=COP of refrigerator – 2
d) COP of pump=COP of refrigerator + 2
View Answer
Explanation: This relation comes from the COP of pump and refrigerator.
7. Heat leakage from a heat pump to surroundings is always greater than work done on pump.
a) true
b) false
View Answer
Explanation: (Heat leakage from a heat pump to surroundings)=(COP of refrigerator + 1)*(work done on pump).
8. Which of the following statements are true?
a) a heat pump provides a thermodynamic advantage over direct heating
b) COP for both refrigerator and pump cannot be infinity
c) work input for both refrigerator and pump is greater than zero
d) all of the mentioned
View Answer
Explanation: W is the electrical energy used to drive the pump or refrigerator which cannot be zero.
9. Kelvin-Planck’s and Clausius’ statements are
a) not connected to each other
b) virtually two parallel statements of second law
c) violation of one doesn’t violate the other
d) none of the mentioned
View Answer
Explanation: Kelvin-Planck’s and Clausius’ statements are equivalent in all aspects.
10. If one of the Kelvin-Planck’s or Clausius’ statement is violated, then other is also violated.
a) true
b) false
View Answer
Explanation: This shows the equivalence of Kelvin-Planck’s and Clausius’ statements.
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