Latest Refrigeration and Air Conditioning mcq with answers

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Latest Refrigeration and Air Conditioning Questions and Answers

53. Pick up the wrong statement. A refrigerant should have
(a) Tow specific heat of liquid
(b) high boiling point
(c) high latent heat of vaporisation
(d) higher critical temperature
(e) low specific volume of vapour.
Ans: b

54. A standard ice point temperature corresponds to the temperature of
(a) water at 0°C
(b) ice at – 4°C
(c) solid and dry ice
(d) mixture of ice, water and vapour under equilibrium conditions under NTP conditions
(e) mixture of ice and water Under equilibrium conditions.
Ans: e

54. Vapour compression refrigeration is some what like
(a) Carnot cycle
(b) Rankine cycle
(c) reversed Camot cycle
(d) reversed Rankine cycle
(e) none of the above.
Ans: e

55. Which of the following cycles uses air as the refrigerant
(a) Ericsson
(b) Stirling
(c) Carnot
(d) Bell-coleman
(e) none of the above.
Ans: d

56. Ammonia-absorption refrigeration cycle requires
(a) very little work input
(b) maximum work input
(c) nearly same work input as for vapour compression cycle
(d) zero work input
(e) none of the above.
Ans: a

57. An important characteristic of absorption system of refrigeration is
(a) noisy operation
(b) quiet operation
(c) cooling below 0°C
(d) very little power consumption
(e) its input only in the form of heating.
Ans: b

58. The relative coefficient of performance is
(a) actual COP/fheoretical COP
(b) theoretical COP/actual COP
(c) actual COP x theoretical COP
(d) 1-actual COP x theoretical COP
(e) 1-actual COP/fheoretical COP.
Ans: a

61. In vapour compression cycle, the conditii of refrigerant is saturated liquid
(a) after passing through the condenser
(b) before passing through the condensei
(c) after passing through the expansion throttle valve
(d) before entering the expansion valve
(e) before entering the compressor.
Ans: a

62. In vapour compression cycle, the condition of refrigerant is very wet vapour
(a) after passing through the condenser
(b) before passing through the condenser
(c) after passing through the expansion or throttle valve
(d) before entering the expansion valve
(e) before entering the compressor.
Ans: e

63. In vapour compression cycle, the condition of refrigerant is high pressure saturated liquid
(a) after passing through the condenser
(b) before passing through the condenser
(c) after passing through the expansion or thiottle valve
(d) before entering the expansion valve
(e) before entering the compressor.
Ans: d

64. In vapour compression cycle the condition of refrigerant is superheated vapour
(a) after passing through the condenser
(b) before passing through the condenser
(c) after passing through the expansion or throttle valve
(d) before [entering the expansion valve
(e) before entering the compressor.
Ans: b

65. In vapour compression cycle the condition off refrigerant is dry saturated vapour
(a) after passing through the condenser
(b) before passing through the condenser
(c) after passing through the expansion or throttle valve
(d) before entering the expansion valve
(e) before entering the compressor..
Ans: e

66. The boiling point of ammonia is
(a) -100°C
(b) -50°C
(c) – 33.3°C
(d) 0°C
(e) 33.3°C.
Ans: c

67. One ton of refrigeration is equal to the refrigeration effect corresponding to melting of 1000 kg of ice
(a) in 1 hour
(b) in 1 minute
(c) in 24 hours
(d) in 12 hours
(e) in 10 hours.
Ans: c

68. One ton refrigeratiqn corresponds to
(a) 50 kcal/min
(b) 50 kcal/kr
(c) 80 kcal/min
(d) 80 kcal/hr
(e) 1000 kcal/day.
Ans: a

69. In S.J. unit, one ton of refrigeration is equal to
(a) 210 kJ/min
(b) 21 kJ/min
(c) 420 kJ/min
(d) 840 kJ/min
(e) 105 kJ/min.
Ans: a

70. The vapour compression refrigerator employs the following cycie
(a) Rankine
(b) Carnot
(c) Reversed Rankine
(d) Brayton
(e) Reversed Carnot.
Ans: e

71. Allowable pressure on high-pressure side or ammonia absorption system is of the order of
(a) atmospheric pressure
(b) slightly above atmospheric pressure
(c) 2-4 bars
(d) 5-6 bars
(e) 7-10 bars.
Ans: d

72. The moisture in a refrigerant is removed by
(a) evaporator
(b) safety relief valve
(c) dehumidifier
(d) driers
(e) expansion valve
Ans: d

73. The condensing pressure due to the presence of non-condensable gases, as compared to that actually required for condensing temperatures without non-condensable gases,
(a) will be higher
(b) will be lower
(c) will remain unaffected
(d) may be higher or lower depending upon the nature of non-condensable gases
(e) unpredictable.
Ans: a

74. Critical pressure of a liquid is the pressure
(a) above which liquid will remain liquid
(b) above which liquid becomes gas
(c) above which liquid becomes vapour
(d) above which liquid becomes solid
(e) at which all the three phases exist together.
Ans: a

75. Critical temperature is’ the temperature above which
(a) a gas will never liquefy
(b) a gas will immediately liquefy
(c) water will evaporate
(d) water will never evaporate
(e) none of the above.
Ans: a

76. The refrigerant for a refrigerator should have
(a) high sensible heat
(b) high total heat
(c) high latent heat
(d) low latent heat
(e) low sensible heat
Ans: c

77. Rating of a domestic refrigerator is of the order of
(a) 0.1 ton
(b) 5 tons
(c) 10 tons
(d) 40 tons
(e) 100 tons.
Ans: a

78. The COP of a domestic refrigerator
(a) is less than 1
(b) is more than 1
(c) is equal to 1
(d) depends upon the make
(e) depends upon the weather conditions.
Ans: b

79. The domestic refrigerator uses following type of compressor
(a) centrifugal
(b) axial
(c) miniature sealed unit
(d) piston type reciprocating
(e) none of the above.
Ans: d

80. Presence of moisture in a refrigerant affects the working of
(a) compressor
(b) condenser
(c) evaparator
(d) expansion valve.
(e) heat transfer.
Ans: d

81. Refrigeration in aeroplanes usually employs the following refrigerant
(a) Co2
(b) Freon-11
(c) Freon-22
(d) Air
(e) none of the above.
Ans: d

82. Domestic refrigerator working on vapour compression cycle uses the following type of expansion device
(a) electrically operated throttling valve
(b) manually operated valve
(c) thermostatic valve
(d) capillary tube
(e) expansion valve.
Ans: d

83. Air refrigeration operates on
(a) Carnot cycle
(b) Reversed Carnot cycle
(c) Rankine cycle
(d) Erricson cycle
(e) Brayton cycle.
Ans: e