refrigeration and air conditioning MCQs – Page 3

Practise focused refrigeration and air conditioning questions with marked answers for exam preparation and subject revision.

refrigeration and air conditioning Mcqs
41. On the pressure-enthalpy diagram, condensation and desuperheating is represented by a horizontal line because the process ________________?
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A. takes place at constant enthalpy

B. takes place at constant pressure

C. takes place at constant temperature

D. involves no change in volume

E. takes place at constant entropy

42. Short horizontal lines on pressure-enthalpy chart show__________________?
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A. constant volume lines

B. constant entropy lines

C. constant total heat lines

D. constant pressure lines

E. constant temperature lines

43. An important characteristic of absorption system of refrigeration is__________________?
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A. quiet operation

B. its input only in the form of heating

C. cooling below 0C

D. noisy operation

E. very little power consumption

44. Which of the following refrigerants has lowest freezing point_______________?
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A. Freon-22

B. Freon-12

C. NH3

D. S02

E. C02

45. The change in evaporator temperature in a refrigeration cycle, as compared to change in condenser temperature, influences the value of C.O.P_____________________?
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A. none of the above

B. unpredictable

C. more

D. equally.

E. less

46. Accumulators should have adequate volume to store refrigerant charge at least_________________?
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A. 50%

B. 25%

C. 100%

D. 10%

E. 75%

47. In vapour compression cycle using NH3 as refrigerant, initial charge is filled at_________________?
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A. low pressure side near receiver

B. anywhere in the cycle

C. high pressure side close to receiver

D. delivery of compressor

E. suction of compressor

48. The C.O.P. of a refrigeration cycle with lowering of condenser temperature, keeping the evaporator temperature constant, will__________________?
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A. may increase or decrease depending on the type of refrigerant used

B. unpredictable

C. remain unaffected

D. increase

E. decrease

49. Air refrigeration cycle is used in ____________________?
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A. commercial refrigerators

B. such a cycle does not exist

C. gas liquefaction

D. domestic refrigerators

E. air conditioning

50. The advantage of dry compression is that________________?
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A. none of the above

B. it permits higher speeds to be used

C. it permits complete evaporation in the evaporator

D. all of the above

E. it results in high volumetirc and mechanical efficiency

51. For better COP of refrigerator, the pressure range corresponding to temperature in evaporator and condenser must be____________________?
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A. high

B. euqal

C. under some conditions small and under some conditions high

D. anything

E. small
52. In vapor compression cycle the condition off refrigerant is dry saturated vapor________________?
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A. before entering the expansion valve

B. before passing through the condenser

C. before entering the compressor

D. after passing through the condenser

E. after passing through the expansion or throttle valve

53. Air refrigeration operates on_____________________?
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A. Rankine cycle

B. Reversed Carnot cycle

C. Erricson cycle

D. Brayton cycle

E. Carnot cycle

54. The vapor compression refrigerator employs the following cycle_________________?
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A. Reversed Carnot

B. Brayton

C. Carnot

D. Reversed Rankine

E. Rankine

55. In a refrigeration cycle, the flow of refrigerant is controlled by___________________?
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A. condenser

B. all of the above

C. evaporator

D. expansion valve

E. compressor

56. In refrigerators, the temperature difference between the evaporating refrigerant and the medium being cooled should be_________________?
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A. as low as possible (3 to 11C)

B. zero

C. high, of the order of 25

D. none of the above

E. any value

57. Refrigeration in aeroplanes usually employs the following refrigerant___________________?
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A. Freon-11

B. Freon-22

C. Co2

D. none of the above

E. Air
58. The higher temperature in vapour compression cycle occurs at____________________?
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A. receiver

B. compressor discharge

C. expansion valve

D. evaporator

E. condenser discharge

59. The general rule for rating refrigeration systems (excepting for C02 system) is to approximate following h.p. per ton of refrigeration__________________?
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A. 0.5 to 0.8 h.p. per ton of refrigeration

B. 2 to 5 h.p. per ton of refrigeration

C. 0.1 to 0.5 h.p. per ton of refrigeration

D. 5 to 10 h.p. per ton refrigeration

E. 1 to 2 h.p. per ton of refrigeration
60. The lower horizontal line of the refrigeration cycle plotted on pressure-enthalpy-diagram represents_____________________?
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A. metering of the refrigerant liquid

B. none of the above

C. evaporation of the refrigerant liquid

D. compression of the refrigerant vapour

E. condensation of the refrigerant vapour