MCQ
2221.
Which of the following refrigerant has the lowest freezing point?
R-11
R-22
R-12
Ammoma
2222.
The subcooling in a refrigeration cycle-
does not alter COP
dreases COP
increases COP
none of these
2223.
The temperature of ammonia after compression in a vapour compression system is-
20 to 50°C
70 to 100°C
50 to 70°C
none of these
2224.
The superheating in a refrigeration cycle-
does not alter COP
decreases COP
increases COP
none of these
2225.
A good refrigerant should have-
high latent heat of vaporisation and low freezing point
high operating pressures and low freezing point
high specific volume and high latent heat of vaporisation
low COP and low freezing point
2226.
A refrigerant with the highest critical pressure is-
R-11
R-22
R-12
Ammonia
2227.
Which of the following refrigerant is highly toxic and flammable?
sulphur dioxide
Freon-12
Ammonia
Carbon dioxide
2228.
A domestic refrigerator has the co- efficient of performance-.
equal to 10
less than 10
more than 10
none
2229.
Zeroth law of thermodynamics-
Deals with conversion of mass and energy
Deals with reversibility and irreversibility of process
States that if two systems are both in equilibrium with a third system, they are in thermal equilibrium with each other
Deals with heat engines
2230.
The COP of the vapour absorption cycle as compared to vapour compression cycle is—
higher
lower
same
none of above.
2231.
In order to collect liquid refrigerant and to prevent if from going to a----- device known as necumulator is used at the suction of compressor.
compressor
expansion valve
condenser
evaporator
2232.
The capacity of a domestic refrigerator is the range of-
0.1 to 0.3 TR
1 to 3 TR
3 to 5 TR
5 to 7 TR
2233.
A standard ice point temperature corresponds to the temperature of-.
water at 0°C
ice at-4°C
solid and dry ice
mixture of ice and water under equilibrium conditions
2234.
A vapour absorption refrigerator uses ........ us a refrigerant.
water
ammonia
freon
aqua-ammonia
2235.
The pipe material for the refrigetors sing ammonia as refrigerant should be of--
copper
cast steel or wrought iron
brass
aluminium
2236.
During a refrigeration cycle heat is rejected by the refrigerant in a-
compressor
condenser
evaporator
expansion valve
2237.
A condenser of refrigeration system rejects heat at the rate of 120kW while its compressor consunes a power of 30 kW. The coefficient of performance of the system would be-
1/4
3
4
1/3
2238.
In a domestic vapour compression refrigerator, the refrigerant commonly used is-
CO
Ammonia
R-12
all of these
2239.
The function of oil separator in vapour compression refrigerator is to-
lubricate the compressor
Prevent the oil being carried to condenser
reduce the heat transfer effeciency
none of the above
2240.
In vapour compressor is used—
a vapour compressor is used
a liquid pump is used
both a vapour compressor and a liquid pump is used
none of above