A carnot refrigerating cycle used in house air-conditioning delivers heat to the surroundings at the rate of 10kW of power. The coefficient of performance of this refrigerator would be
1.5
1.67
2.5
0.6
If a carnot refrigeration cycle is to have a coefficient of performance of 5, the ratio of maximum temperature to minimum temperature in the cycle should be
1.2
1.5
2.0
2.5
One ton of refrigeration is equivalent to
1 kW
2.5 Kw
3.5 kW
5 kW
The domestic refrigerator has a refrigerating load of the order of
Less than 0.25 ton
Between 0.5 and 1 ton
More than 1 ton
More than 5 ton
The refrigerating capacity of 165 domestic refrigerator is approximately equal to
0.05 ton
0.1 ton
2 ton
5 ton
Round the clock cooling of an apartment having a load of 300 MJ/day requires an airconditiioning plant of capacity about
1 ton
5 ton
10 ton
25 tons
Which of the following statements is not true?
The coefficient of performance of a refrigerator is generally greater than one
The coefficient of performance of a heat pump equals the reciprocal of thermal efficiency of an engine working within the same temperature limits
The horse power per ton of refrigeration equals 4.75 times the coefficient of performance
The refrigerating effect corresponding to one ton of refrigeration is nearly equal to 210 kJ/min
The refrigerating system of passenger air-craft works on reversed
Brayton cycle
Atkinson cycle
Ericsson cycle
Carnot cycle
A bell-coleman cycle is a reversed
Brayton cycle
Atkinson cycle
Ericsson cycle
Carnot cycle
The presence of frost on the cooling coils of the evaporator of a refrigeration system
Increases the compressor pressure
Acts as the insulator and decreases the heat transfer rate
Makes the compressor run for comparatively short durations
Reduce the life of cooling coils
In an ice plant; the evaporator temperature has been lowered whilst the condenser temperature is maintained constant. The power consumption of the compressor will
Fall
Rise
Remain unchanged
May rise or fall depending on the refrigerant used
The effect of changing the evaporator temperature on coefficient of performance as compared to that of changing the condenser temperature is
More pronounced
Less pronounced
Same effect in each case
Depends on the refrigerant used
A clicking sound was heard in the expansion valve of a newly charged ammonia compressor system. This could be due to
Leakage of ammonia
Less charge of ammonia
Excessive charge of ammonia
Evaporator coils choked
Most of the refrigeration systems are having a rating of ………..per ton of refrigeration
0.1 to 0.25
0.3 to 0.8
1 to 2
3 to 5
Air-conditioning is the simultaneous control of………in a confined space
Temperature and air movement
Temperature and humidity
Temperature, humidity and air movement
Temperature, humidity, purity and movement of air