The COP of a Carnot refrigeration cycle decreases on
Decreasing the difference in operating temperatures
Keeping the upper temperature constant and increasing the lower temperature
Increasing the upper temperature and keeping the lower temperature constant
Increasing the upper temperature and decreasing the lower temperature
For the same operating temperature limits, the coefficient of performance (COP) of a heat pump equals
COP of refrigerator
1+(COP of refrigerator)
(COP of refrigerator)-1
The function of receiver in a refrigeration plant to
Superheat the refrigerant gas
Reduce the power consumption
Allow for variation of load
Increase the refrigerant effect by allowing complete evaporation in the evaporator
Secondary refrigerant is invariably used in
Water coolers
Deep freezers
Ice plants
Domestic refrigerators
Window type air conditioners
The refrigerant obtained by mixing two refrigerants in proper proportion is called
Secondary refrigerant
Auxiliary refrigerant
Azeotrope
Synthetic refrigerant
The brine is an aqueous solution of ………..in water
Sodium chloride
Calcium carbonate
Sodium bicarbonate
Magnesium sulphate
Dry ice is
Solidified carbon dioxide
Ice free from dissolved air and gases
Ice free from impurities
Ice made from transparent distilled water
For producing cooling effect equivalent to one ton of refrigeration, the mass of ammonia circulated in vapour compression system is nearly equal to
0.2 kg
0.5 kg
1.0 kg
1.5 kg
The function of halide torch is
Defrosting of cooling coil
Super heating of vapour refrigerant
Detecting leakage of refrigerant
Facilitating better lubrication in the refrigerator
In a vapour compression system using Freon-12 as the refrigerant, the mass of feron-12 circulated per ton of refrigeration is nearly equal to
0.2 kg
1.0 kg
2.0 kg
2.5 kg
For the same refrigeration load and source temperature limits in a vapour compression refrigeration system, the required mass flow rates of ammonia and Freon-12 generally conform to the ratio
1:2
1:4
1:7
1:10
When a R-22 refrigeration system is charged with R-12; the system will
Not function
Operate at low temperature
Have considerable fluctuations in the operating pressures
Have its refrigeration capacity reduced to about one-third
The pressures in the evaporator and condenser coils of a refrigeration system have been noted to be equal. This suggests that
The system is not functioning
The evaporator load is minimum
The refrigerant is wet at entry to and at exit from the compressor
There is leakage of refrigerant
The compressor of a domestic refrigerator has been noted to run for comparatively large durations. That indicates
Highly efficient operation
Over loading of the machine
Capillary tube choked
Thermostat gone defective
The performance of which of the following units in a vapour cmpression system is adversely affected by the presence of moisture?
Condenser
Expansion valve
Evaporator
Compressor