100 TOP Refrigeration and Air Conditioning Multiple choice Questions and Answers pdf

71. On the pressure-enthalpy diagram, condensation and desuperheating is represented by a horizontal line because the process
(a)    involves no change in volume
(b)    takes place at constant temperature
(c)    takes place at constant entropy
(d)    takes place at constant enthalpy
(e)    takes place at constant pressure.
Ans: e

72.   One ton of the refrigeration is
(a)    the standard unit used in refrigeration problems
(b)    the cooling effect produced by melting 1 ton of ice
(c)    the refrigeration effect to freeze 1 ton of water at 0°C into ice at 0°C in 24 hours
(d)    the refrigeration effect to produce 1 ton of ice at NTP conditions
(e)    the refrigeration effect to produce 1 ton of ice in 1 hour time.
Ans: c

73.    Super heating in a refrigeration cycle
(a)     increases COP
(b)     decreases COP
(c)     COP remains unaltered
(d)     other factors decide COP
(e)     unpredictable.
Ans: b

74.    For proper refrigeration in a cabinet, if the temperature and vapour pressure difference between cabinet and atmosphere is high, then
(a)     bigger cabinet should be used
(b)    smaller cabinet should be used
(c)    perfectly tight vapour seal should be used
(d)    refrigerant with lower evaporation temperature should be used
(e)    refrigerant with high boiling point must be used.
Ans: c

75.    Choose the correct statement
(a)    A refrigerant should have low latent heat
(b)    If operating temperature of system is low, then refrigerant with low boiling point should be used
(c)    Precooling and subcooling bf refrigerant are same
(d)    Superheat and sensible heat of a. refrigerant are same
(e)    Refrigerant is inside the lubes in case of a direct-expansion chiller.
Ans: b

76.    The suction pipe diameter of refrigerating unit compressor in comparison to delivery side is
(a)     bigger 
(b)     smaller
(c)    equal
(d)    smaller/bigger depending on capacity
(e)    unpredictable.
Ans: a

77.    Moisture in freon refrigeration system causes
(a)    ineffective refrigeration
(b)    high power consumption
(c)    freezing automatic regulating valve
(d)    corrosion of whole system
(e)    breakdown of refrigerant.
Ans: c

78.    The advantage of dry compression is that
(a)    it permits higher speeds to be used
(b)    it permits complete evaporation in the evaporator
(c)    it results in high volumetric and mechanical efficiency
(d)    all of the above
(e)     none of the above.
Ans: d

79.    Choose the wrong statement
(a)    Temperature of medium being cooled must be below that of the evaporator
(b)    Refrigerant leaves the condenser as liquid
(c)    All solar thermally operated absorption systems are capable only of intermittent operation
(d)    frost on evaporator reduces heat transfer
(e)    refrigerant is circulated in a refrigeration system to transfer heat.
Ans: a

80.    Under-cooling in a refrigeration cycle
(a)     increases COP
(b)     decreases COF
(c)    COP remains unaltered
(d)    other factors decide COP
(e)    unperdictable.
Ans: a

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