Heat Transfer, Refrigeration and Air Conditioning – Section 1

41. During a refrigeration cycle, heat is rejected by the refrigerant in a

A. compressor
B. condenser
C. evaporator
D. expansion valve

Correct Answer: B. condenser

42. A refrigeration system

A. removes heat from a low temperature body and delivers it to a high temperature body
B. removes heat from a high temperature body and delivers it to a low temperature body
C. rejects energy to a low temperature body
D. none of the above

Correct Answer: A. removes heat from a low temperature body and delivers it to a high temperature body

43. The subcooling in a refrigeration cycle

A. does not alter C.O.P.
B. increases C.O.P.
C. decreases C.O.P.
D. none of these

Correct Answer: B. increases C.O.P.

44. Nusselt number (NN) is given by

ht-se1-44

Correct Answer: Option A

45. During sensible cooling of air __________ decreases.

A. wet bulb temperature
B. relative humidity
C. dry bulb temperature
D. specific humidity

Correct Answer: C. dry bulb temperature

46. The critical radius is the insulation radius at which the resistance to heat flow is

A. maximum
B. minimum
C. zero
D. none of these

Correct Answer: B. minimum

47. In case of solids, the heat transfer takes place according to radiation.

A. Correct
B. Incorrect

Correct Answer: B. Incorrect

48. A water cooled condenser operates at a __________ condensing temperature than an air-cooled condenser.

A. higher
B. lower

Correct Answer: B. lower

49. The relative humidity decreases as air gets wet.

A. True
B. False

Correct Answer: A. True

50. The temperature of ammonia after compression in a vapor compression system is

A. 20 to 50° C
B. 50 to 70° C
C. 70 to 110° C
D. none of these

Correct Answer: C. 70 to 110° C

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