Mechanical Engineering - Heat Transfer, Refrigeration and Air Conditioning

16. 

A condenser is used in the __________ pressure side of a refrigerating system.

A. low
B. high

Answer: Option B

Explanation:

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17. 

A steam pipe is to be lined with two layers of insulating materials of different thermal conductivities. For the minimum heat transfer,

A. the better insulation must be put inside
B. the better insulation must be put outside
C. one could place either insulation on either side
D. one should take into account the steam temperature before deciding as to which insulation is put where

Answer: Option A

Explanation:

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18. 

In a parallel flow heat exchanger, the rate of flow of heat and the rate of decrease of temperature are maximum.

A. Yes
B. No

Answer: Option A

Explanation:

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19. 

When the air is passed through an insulated chamber having sprays of water maintained at a temperature higher than the dew point temperature of entering air but lower than its dry bulb temperature, then the air is said to be

A. cooled and humidified
B. cooled and dehumidified
C. heated and humidified
D. heated and dehumidified

Answer: Option A

Explanation:

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20. 

Which of the following statement is wrong?

A. The performance of the vapour compression refrigerator varies considerably with both vaporising and condensing temperatures.
B. In vapour compression cycle, the useful part of the heat transfer is at the condenser.
C. In ammonia-hydrogen (electolux) refrigerator, no compressor, pump or fan is required.
D. The effect of under-cooling the liquid refrigerant is to decrease the coefficient of performance.

Answer: Option D

Explanation:

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