Mechanical Engineering - Heat Transfer, Refrigeration and Air Conditioning

36. 

The mass of water vapour present in 1 kg of dry air, is called humidity ratio.

A. True
B. False

Answer: Option A

Explanation:

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37. 

In a vapour compression refrigeration system, a throttle valve is used in place of an expander because

A. it considerably reduces mass of the system
B. it improves the C.O.P., as the condenser is small
C. the positive work in isentropic expansion of liquid is very small
D. it leads to significant cost reduction

Answer: Option C

Explanation:

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38. 

The unit of overall coefficient of heat transfer is

A. W/m2K
B. W/m2
C. W/mK
D. W/m

Answer: Option A

Explanation:

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39. 

Most thermostatic expansion valves are set for a superheat of

A. 5°C
B. 10°C
C. 15°C
D. 20°C

Answer: Option A

Explanation:

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40. 

For large tonnage (more than 200 TR) air-conditioning applications, the compressor recommended is

A. reciprocating
B. rotating
C. centrifugal
D. screw

Answer: Option C

Explanation:

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