Mechanical Engineering - Heat Transfer, Refrigeration and Air Conditioning

21. 

It is desired to condition the outside air from 70% relative humidity and 45° C dry bulb temperature to 50% relative humidity and 25° C dry bulb temperature (room condition). The practical arrangement will be

A. dehumidification
B. cooling and humidification
C. cooling and dehumidification
D. dehumidification and pure sensible cooling

Answer: Option C

Explanation:

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22. 

During heating and dehumidification process, dry bulb temperature

A. remains constant
B. increases
C. decreases

Answer: Option B

Explanation:

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23. 

The C.O.P. of a refrigerator working on a reversed Carnot cycle is (where T1 = Lowest absolute temperature, and T2 = Highest absolute temperature)

A.
B.
C.
D.

Answer: Option A

Explanation:

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24. 

A refrigerant compressor is used to

A. raise the pressure of the refrigerant
B. raise the temperature of the refrigerant
C. circulate the refrigerant through the refrigerating system
D. all of the above

Answer: Option D

Explanation:

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25. 

In which of the following refrigeration system, waste heat can be effectively used?

A. Vapour compression cycle
B. Vapour absorption cycle
C. Air refrigeration cycle
D. none of these

Answer: Option B

Explanation:

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