Mechanical Engineering - Heat Transfer, Refrigeration and Air Conditioning

36. 

During adiabatic saturation process on unsaturated air __________ remains constant.

A. relative humidity
B. dew point temperature
C. dry bulb temperature
D. wet bulb temperature

Answer: Option D

Explanation:

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37. 

The thickness of thermal and hydrodynamic boundary layer is equal if Prandtl number is

A. equal to one
B. greater than one
C. less than one
D. equal to Nusselt number

Answer: Option A

Explanation:

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38. 

A perfect black body is one which

A. is black in colour
B. absorbs heat radiations of all wave lengths falling on it
C. reflects all the heat radiations
D. transmits the heat radiations

Answer: Option B

Explanation:

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39. 

Degree of saturation or percentage humidity is

A. the mass of water vapour present in 1 m3 of dry air
B. the mass of water vapour present in 1 kg of dry air
C. the ratio of the actual mass of water vapour in a unit mass of dry air to the mass of water vapour in the same mass of dry air when it is saturated at the same temperature and pressure.
D. the ratio of actual mass of water vapour in a given volume of moist air to the mass of water vapour in the same volume of saturated air at the same temperature and pressure

Answer: Option C

Explanation:

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40. 

The coefficient of performance of Heat Pump is always __________ one.

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

Answer: Option C

Explanation:

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