Objective Refrigeration and Air Conditioning - Mechanical Engineering Questions and Answers pdf

61.    In a refrigeration cycle, the flow of refrigerant is controlled by
(a)     compressor   
(b)     condenser
(c)     evaporator    
(d)     expansion valve
(e)     all of the above.
Ans: d

62.    Where does the lowest temperature occur in a vapour compression cycle ?
(a)     condenser
(b)     evaporator
(c)     compressor   
(d)     expansion valve
(e)     receiver.
Ans: b

63.    The leaks in a refrigeration system using Freon are detected by
(a)    halide torch which on detection produces greenish flame lighting
(b)    sulphur sticks which on detection gives white smoke
(c)    using reagents
(d)     smelling
(e)     sensing reduction in pressure.
Ans: a

64.    rick up the incorrect statement
(a)    lithium bromide used in vapour absorption cycle is nonvolatile
(b)    lithium bromide plant can't operate below 0°C
(c)    a separator is used in lithium bromide plant to remove the unwanted water vapour by condensing
(d)    concentration of solution coming out of lithium bromide generator is more in comparison to that entering the generator
(e)    weak solution in liquid heat exchanger gives up heat to the strong solution.
Ans: c

65.    The lower horizontal line of the refrigeration cycle plotted on pressure-enthalpy-diagram represents
(a)    condensation of the refrigerant vapour
(b)    evaporation of the refrigerant liquid
(c)    compression of the refrigerant vapour
(d)    metering of the refrigerant liquid
(e)    none of the above.
Ans: b

66.    Mass flow ratio of NH3 in comparison to Freon-12 for same refrigeration load and same temperature limits is of the order of
(a)     1 : 1
(b)     1 : 9
(c)     9 : 1
(d)     1 : 3
(e)     3 : 1
Ans: b

67.    Freon group of refrigerants are
(a)     inflammable
(d)    toxic
(c)    non-inflammable and toxic
(d)    non-toxic and inflammable
(e)    non-toxic and non-inflammable.
Ans: e

68   Ammonia is
(a)     non-toxic
(b)     non-inflammable
(c)    toxic and non-inflammable
(d)    highly toxic and inflammable
(e)     none of the above.
Ans: d

69. In vapour compression cycle using NH3 as refrigerant, initial charge is filled at
(a)    suction of compressor
(b)    delivery of compressor
(c)    high pressure side colse to receiver
(d)    low pressure side near receiver
(e)    anywhere in the cycle.
Ans: c

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

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