Mechanical Engineering - Heat Transfer, Refrigeration and Air Conditioning

16. 

In aqua-ammonia and Lithium-bromide water absorption refrigeration systems, the refrigerants are respectively

A. water and water
B. water and lithium bromide
C. ammonia and lithium bromide
D. ammonia and water

Answer: Option D

Explanation:

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17. 

As relative humidity decreases, the dew point temperature will be __________ wet bulb temperature.

A. same as
B. lower than
C. higher man

Answer: Option B

Explanation:

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18. 

The process of heat transfer from a hot body to a cold body, in a straight line, without affecting the intervening medium, is called radiation.

A. True
B. False

Answer: Option A

Explanation:

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19. 

Reynolds number (RN) is given by (where h = Film coefficient, l = Linear dimension, V = Velocity of fluid, k = Thermal conductivity, t = Temperature, ρ = Density of fluid, cp = Specific heat at constant pressure, and μ = Coefficient of absolute viscosity)

A.
B.
C.
D.

Answer: Option C

Explanation:

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20. 

The optimum effective temperature for human comfort is

A. higher in winter than in summer
B. lower in winter than in summer
C. same in winter and summer
D. not dependent on season

Answer: Option B

Explanation:

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