Mechanical Engineering - Heat Transfer, Refrigeration and Air Conditioning

26. 

The condition of refrigerant after passing through the expansion or throttle valve, in a vapour compression system is

A. high pressure saturated liquid
B. wet vapour
C. very wet vapour
D. dry vapour

Answer: Option C

Explanation:

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27. 

The process of adding moisture to the air, without change in its dry bulb temperature, is known as humidification.

A. Agree
B. Disagree

Answer: Option A

Explanation:

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28. 

In case of liquids and gases, the heat transfer takes place according to

A. conduction
B. convection
C. radiation
D. none of these

Answer: Option B

Explanation:

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29. 

The logarithmic mean temperature difference (tm) is given by (where Δt1 and Δt2 are temperature differences between the hot and cold fluids at entrance and exit)

A.
B.
C. tm = (Δt1 - Δt1) loget1t1)
D.

Answer: Option A

Explanation:

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30. 

The radiation emitted by a black body is known as

A. black radiation
B. full radiation
C. total radiation
D. all of these

Answer: Option D

Explanation:

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