Tricky Refrigeration and Air Conditioning Multiple choice Questions and Answers pdf

81.    For obtaining high COP, the pressure range of compressor should be
(a)     high 
(b)     low
(c)     optimum 
(d)     any value
(e)     there is no such criterion.
Ans: b

82.    The coefficient of performance is the ratio of the refrigerant effect to the
(a)    heat of compression
(b)    work done by compressor
(c)    enthalpy increase in compressor
(d)    all of the above
(e)    none of the above.
Ans: d

83.    The C.O.P of a refrigeration cycle with increase in evaporator temperature, keeping condenser temperature constant, will
(a)     increase 
(b)     decrease
(c)    remain unaffected
(d)    may increase or decrease depending on the type of refrigerant used
(e)     unpredictable.
Ans: a

84.    Vertical lines on pressure-enthalpy chart show constant
(a)     pressure lines
(b)     temperature lines
(c)    total heat lines
(d)    entropy lines 
(e)     volume lines.
Ans: c

85.    Most of the domestic refrigerators work on the following refrigeration system
(a)    vapour compression
(b)    vapour absorption
(c)    carnot cycle
(d)    electrolux refrigerator
(e)    dual cycle.
Ans: a

86.    The general rule for rating refrigeration systems (excepting for C02 system) is to approximate following h.p. per ton of refrigeration
(a)    0.1 to 0.5 h.p. per ton of refrigeration
(b)    0.5 to 0.8 h.p. per ton of refrigeration
(c)    1 to 2 h.p. per ton of refrigeration
(d)     2 to 5 h.p. per ton of refrigeration
(e)     5 to 10 h.p. per ton refrigeration.
Ans: c

87.    Reducing suction pressure in refrigeration cycle
(a)    lowers evaporation temperature
(b)    increases power required per ton of refrigeration
(c)    lowers  compressor  capacity  because vapour is lighter
(d)    reduces weight displaced by piston
(e)    all of the above.
Ans: e

88.    Cooling water is required for following equipment in ammonia absorption plant
(a)     condenser 
(b)     evaporator
(c)    absorber
(d)    condenser and absorber
(e)    condenser, absorber and separator (rectifier).
Ans: e


89.    The refrigeration effect in a dry evaporator compared to flooded evaporator in a similar plant is
(a)     same 
(b)     more
(c)    less
(d)    more or less depending on ambient conditions
(e)    unpredictable.
Ans: c

90.    The C.O.P. of a refrigeration cycle with lowering of condenser temperature, keeping the evaporator temperature constant, will
(a)     increase 
(b)     decrease
(c)    may increase or decrease depending on the type of refrigerant used
(d)    remain unaffected
(e)    unpredictable.
Ans: a

91.    Which of the following refrigerants has lowest freezing point
(a)     Freon-12 
(b)     NH3
(c)     C02 
(d)     Freon-22
(e)     S02.
Ans: d

92.    The COP of a vapour compression plant in comparison to vapour absorption plant is
(a)    more
(b)    less
(c)    same
(d)    more/less depending on size of plant
(e)    unpredictable.
Ans: a

93.    The C.O.P. of a domestic refrigerator in comparison to domestic air conditioner will be
(a)     same 
(b)     more
(c)    less
(d)    dependent on weather conditions
(e)    unpredictable.
Ans: c

94.    The evolution of heat of solution takes place in ammonia absorption plant when
(a)    ammonia vapour goes into solution
(b)    ammonia vapour is driven out of solution
(c)    lithium bromide mixes with ammonia
(d)    weak solution mixes with strong solution
(e)    lithium bromide is driven out of solution.
Ans: a

95.   The change in evaporator temperature in a refrigeration cycle, as compared to change in condenser temperature,  influences the value of C.O.P.
(a)     more 
(b)     less
(c)     equally. 
(d)     unpredictable
(e)     none of the above.
Ans: a

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