Heat Transfer, Refrigeration and Air Conditioning - Section 1 (6)

Directions to Solve

Heat Transfer, Refrigeration and Air Conditioning - Section 1

41.

Defrosting of a refrigerator may be done by stopping the compressor for a short period.

A.	Correct
B.	Incorrect

Answer: Option A

Explanation:

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42.

The difference between dry bulb temperature and wet bulb temperature, is called

A.	dry bulb depression
B.	wet bulb depression
C.	dew point depression
D.	degree of saturation

Answer: Option B

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43.

The by-pass factor for a cooling coil

A.	increases with increase in velocity of air passing through it
B.	decreases with increase in velocity of air passing through it
C.	remains unchanged with increase in velocity of air passing through it
D.	may increase or decrease with increase in velocity of air passing through it depending upon the condition of air entering

Answer: Option A

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44.

The formation of frost on cooling coils in a refrigerator

A.	increases heat transfer
B.	improves C.O.P. of the system
C.	increases power consumption
D.	reduces power consumption

Answer: Option C

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45.

The humidity ratio or specific humidity is the mass of water vapour present in

A.	1 m3 of wet air
B.	1 m3 of dry air
C.	1 kg of wet air
D.	1 kg of dry air

Answer: Option D

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46.

In a refrigerating machine, heat rejected is __________ heat absorbed.

A.	equal to
B.	less than
C.	greater than

Answer: Option C

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47.

In free convection heat transfer transition from laminar to turbulent flow is governed by the critical value of the

A.	Reynold's number
B.	Grashoff's number
C.	Reynold's number, Grashoff's number
D.	Prandtl number, Grashoff's number

Answer: Option D

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48.

Which of the following statement is wrong?

A.	The heat transfer in liquid and gases takes place according to convection.
B.	The amount of heat flow through a body is dependent upon the material of the body.
C.	The thermal conductivity of solid metals increases with rise in temperature,
D.	Logarithmic mean temperature difference is not equal to the arithmetic mean temperature difference.

Answer: Option C

Explanation:

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