A refrigerator works on a reversed Carnot cycle. The Coefficient of performance is 7. If the capacity of the refrigerator is 12 TR. What is the value of heat rejected from the system?

A refrigerator works on a reversed Carnot cycle. The Coefficient of performance is 3.5. If the capacity of the refrigerator is 6 TR. Find out the power required to run the refrigerator.

A

5 kW

B

3.5 kW

C

360 kJ/min

D

520 kJ/min

A Carnot heat engine receives heat at 750 K and rejects the waste heat to the environment at 300 K. The net work output of the heat engine is used to drive a Carnot refrigerator, whose COP is 6.14. If the heat removal rate from the refrigerated space is 6.6 kW, determine the rate of heat supply to the heat engine?

A

2.79 kW

B

1.79 kW

C

4.79 kW

D

7.79 kW

Efficiency of a Carnot engine is given as 80%. If the cycle direction be reversed, what will be the value of C.O.P. of reversed Carnot Cycle?

A

1.25

B

0.8

C

0.5

D

0.25

A Korean refrigerator is bought to maintain the cool space at 8°C and a Japanese refrigerator is bought to main the cool space at -20°C in a laboratory room having constant temperature of 25°C. If the both refrigerators run on a reversed Carnot cycle, state the refrigerator that delivers maximum COP.

A

Korean refrigerator

B

Japanese refrigerator

C

both have same COP

D

none of the mentioned

Consider the following statement: a) In a refrigerator the heat is taken out from the system. b) In a refrigerator the heat is given to the system. c) In a heat pump the heat is taken out from the system. d) In a heat pump the heat is given to the system. Which of the above statements are correct?

A

Both a and c are correct

B

Both a and d are correct

C

Both b and c are correct

D

Both b and d are correct

The efficiency of Carnot heat engine is 40%. What is the value of C.O.P. of a refrigerator operating on reversed Carnot cycle?

A

2.5

B

1.5

C

4

D

10

Two refrigerators M and N operate in series. The refrigerator M absorbs energy at the rate of 1 kW from a body at temperature 400 K and rejects energy as heat to a body at a temperature T. The refrigerator N absorbs the same quantity of energy which is rejected by the refrigerator N from the body at temperature T, and rejects energy as heat to a body at temperature 800 K. If both the refrigerators have the same C.O.P., what is the value temperature T?

A

600 K

B

200 K

C

565.68 K

D

459.21 K

The thermal efficiency of a reversible heat engine operating between two given thermal reservoirs is 0.4. The device is used either as a refrigerator or as a heat pump between the same reservoirs. Then the coefficient of performance as a refrigerator (COP)_R and the co-efficient of performance as a heat pump (COP)_HP are

A

(COP)_R = (COP)_HP = 0.6

B

(COP)_R = 2.5; (COP)_HP = 1.5

C

(COP)_R = 1.5; (COP)_HP = 2.5

D

(COP)_R = (COP)_HP = 2.5

A heat pump working on a reversed Carnot cycle has a C.O.P. of 5. It works as a refrigerator taking 1 kW of work input. The refrigerating effect will be

A

1 kW

B

2 kW

C

3 kW

D

4 kW

Group I shows different heat addition processes in power cycles. Likewise, Group II shows different heat removal processes. Group III lists power cycles. Match items from Groups I, II and III. Group I Group II Group III P. Pressure constant S. Pressure constant 1. Rankine cycle Q. Volume constant T. Volume constant 2. Otto cycle R. Temperature constant U. Temperature constant 3. Carnot cycle 4. Diesel cycle 5. Brayton cycle

A

P – S – 5, R – U – 3, P – S – 1, Q – T - 2

B

P – S – 1, R – U – 3, P – S – 4, P – T - 2

C

R – T – 3, P – S – 1, P – T – 4, Q – S - 5

D

P – T – 4, R – S – 3, P – S – 1, P – S - 5

A refrigerator works on a reversed Carnot cycle. The Coefficient of performance is 7. If the capacity of the refrigerator is 12 TR. What is the value of heat rejected from the system?

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