Mechanical Engineering - Heat Transfer, Refrigeration and Air Conditioning

16. 

Thermal conductivity of solid metals __________ with rise in temperature.

A. remains same
B. decreases
C. increases

Answer: Option B

Explanation:

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17. 

The horizontal and non-uniformly spaced lines on a psychrometric chart indicates

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

Answer: Option C

Explanation:

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18. 

A reversible engine has ideal thermal efficiency of 30%. When it is used as a refrigerating machine with all other conditions unchanged, the coefficient of performance will be

A. 1.33
B. 2.33
C. 3.33
D. 4.33

Answer: Option B

Explanation:

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19. 

Which of the following refrigerant is highly toxic and flammable?

A. Ammonia
B. Carbon dioxide
C. Sulphur dioxide
D. R-12

Answer: Option A

Explanation:

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20. 

The unit of Stefan-Boltzmann constant is

A. Watt/mK
B. Watt/m2K2
C. Watt/m2K4
D. Watt/mK2

Answer: Option C

Explanation:

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