Mechanical Engineering - Heat Transfer, Refrigeration and Air Conditioning

21. 

Free convection flow depends on

A. density
B. coefficient of viscosity
C. gravitational force
D. all of these

Answer: Option D

Explanation:

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22. 

The critical pressure of a liquid is the pressure

A. above which a liquid will remain a liquid
B. above which a liquid will explode
C. above which a liquid will always convert into a vapour
D. below which a liquid will always be in vapour form

Answer: Option A

Explanation:

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23. 

Conduction is a process of heat transfer

A. from one particle of the body to another without the actual motion of the particles
B. from one particle of the body to another by the actual motion of the heated particles.
C. from a hot body to a cold body, in a straight line, without affecting the intervening medium
D. none of the above

Answer: Option A

Explanation:

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24. 

Thermal diffusivity of a substance is

A. directly proportional to the thermal conductivity
B. inversely proportional to density of substance
C. inversely proportional to specific heat
D. all of the above

Answer: Option D

Explanation:

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25. 

The sensible heat factor during the heating and humidification process is given by (where h1 = Enthalpy of air entering the heating coil, h2 = Enthalpy of air leaving the heating coil, and hA = Enthalpy of air at the end of humidification process)

A.
B.
C.
D.

Answer: Option D

Explanation:

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