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1 and 2
1, 3 and 4
1, 2 and 4
1, 2, 3 and 4
A carnot refrigerator rejects 3000 kJ of heat at 400oK while using 1000kJ of work. The lowest operating temperature in the cycle should be
15oC
27 oC
-6 oC
0 oC
A carnot engine has an efficiency of 80 percent. If the cycle is reversed in direction and made to operate as a refrigerator, its COP will be
0.25
0.5
0.75
1.25
A condenser of a refrigeration system rejects heat at a rate of 120kW, while its compressor consumes a power of 30kW. The coefficient of performance of the system would be
2
3
4
5
The operating temperature of cold storage is 280 K and the heat leakage from the surroundings is 35 kW for the ambient temperature of 310 K. if the actual COP of ideal refrigeration plant is one-fourth of an ideal plant working between the same temperature limits, the power required to drive the plant would be.
3.7 kW
7.5 kW
12 kW
15 kW
Reference the figure given below, E is a heat engine with efficiency 0.4 and R is a refrigerator
Given that Q2+Q4=3Q1, the COP of the refrigerator is
2.5
3.0
4.0
5.0
A carnot heat pump for domestic heating works between a cold system (the contents of refrigerator cabinet) at 0oC and the water in the radiator system at 80oC. the coefficient of performance of this heat pump would be about
1.4
3.4
4.4
6.2
A heat pump working on a refersed carnot cycle has a COP of 5. if it is made to work as a refrigerator taking 1 kW of work input, the refrigerating effect will be
1 kW
2 kW
3 kW
4 kW
Which one of the followings is a wrong statement?
The coefficient of performance (COP) refers to the ratio of desired effect to the energy supplied to achieve that effect
COP of most of the refricerators and heat pumps is greater than one
Higher the value of COP, more efficient the refrigerators and heat pumps would be
The refrigerators and heat pumps are reversible heat engine
One ton refrigeration machine implies that the machine
Has a gross weight of 1 ton
Consumes one ton of refrigerant in 24 hours
Has the capacity to convert one ton of water into ice
Is capable of extracting heat that would melt one ton of ice at 0oC into water at 0oC in a period of 24 hours
The capcity of refrigerating machine is expressed as
Inside volume of cabinet
Lowest temperature attained
Gross weight of machine in tons
Rate of abstraction of heat from the space being cooled
/
1 and 3
1, 2 and 3
1, 3 and 4
1, 2, 3 and 4
One ton of refrigeration implies that the machine has a refrigerating effect (capacity of heat extraction from the system being cooled) equal to
50 kcal/sec
50 kcal/min
50kcal/hr
50 kcal/day
A refrigeration system
Removes heat from a system at low temperature and transfers the same to a system at high temperature
Delivers less heat to the system at high temperature than it extracts from the system at low temperature
Transfers heat from a high temperature source to a low temperature sink
Violates second law of thermodynamics
Which of the refrigerant from the list given below is least used these days?
Ammonia
Carbon dioxide
Sulphur dioxide
Freon-12