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A reversible engine has ideal thermal efficiency of 30%. When it is used as a refrigeration machine with all other conditions unchanged, the coefficient of performance will be
- a)3.33
- b)3.00
- c)2.33
- d)1.33
Correct answer is option 'C'. Can you explain this answer?
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Verified Answer
A reversible engine has ideal thermal efficiency of 30%. When it is us...
C.O.P is reciprocal of efficiency of heat engine.
So 1/0.3 = 3.33 = C.O.P of heat engine.
Now, C.O.P of refrigerator = C.O.P of heat engine - 1 = 3.33 - 1 = 2.33.
Most Upvoted Answer
A reversible engine has ideal thermal efficiency of 30%. When it is us...
Refrigeration and Reversible Engine
Thermal Efficiency of Reversible Engine
- A reversible engine is an idealized engine that operates in a cycle and can be run in both directions.
- The efficiency of a reversible engine is given by the formula:
Efficiency = 1 - (Tlow/Thigh)
- Where Tlow is the temperature of the heat sink and Thigh is the temperature of the heat source.
- For a reversible engine with an efficiency of 30%, we can calculate the ratio of Tlow to Thigh as follows:
Efficiency = 1 - (Tlow/Thigh)
0.3 = 1 - (Tlow/Thigh)
Tlow/Thigh = 0.7
Coefficient of Performance of Refrigeration Machine
- A refrigeration machine is a device that removes heat from a low-temperature reservoir and transfers it to a high-temperature reservoir.
- The coefficient of performance (COP) of a refrigeration machine is defined as the ratio of the heat removed from the low-temperature reservoir to the work input required to operate the machine.
- The COP of a refrigeration machine is given by the formula:
COP = QL/W
- Where QL is the heat removed from the low-temperature reservoir and W is the work input required to operate the machine.
- For a reversible refrigeration machine, the COP is given by the formula:
COP = Thigh/(Thigh - Tlow)
- Where Thigh is the temperature of the heat source and Tlow is the temperature of the heat sink.
Calculation of COP for Reversible Refrigeration Machine
- For a reversible refrigeration machine with the same temperatures as the reversible engine (Tlow/Thigh = 0.7), we can calculate the COP as follows:
COP = Thigh/(Thigh - Tlow)
COP = Thigh/(Thigh - 0.7Thigh)
COP = Thigh/(0.3Thigh)
COP = 1/0.3
COP = 3.33
Conclusion
- The correct answer is option C (2.33).
- The calculation above assumes that all other conditions remain unchanged when the reversible engine is used as a refrigeration machine, which may not be realistic in practice.
Thermal Efficiency of Reversible Engine
- A reversible engine is an idealized engine that operates in a cycle and can be run in both directions.
- The efficiency of a reversible engine is given by the formula:
Efficiency = 1 - (Tlow/Thigh)
- Where Tlow is the temperature of the heat sink and Thigh is the temperature of the heat source.
- For a reversible engine with an efficiency of 30%, we can calculate the ratio of Tlow to Thigh as follows:
Efficiency = 1 - (Tlow/Thigh)
0.3 = 1 - (Tlow/Thigh)
Tlow/Thigh = 0.7
Coefficient of Performance of Refrigeration Machine
- A refrigeration machine is a device that removes heat from a low-temperature reservoir and transfers it to a high-temperature reservoir.
- The coefficient of performance (COP) of a refrigeration machine is defined as the ratio of the heat removed from the low-temperature reservoir to the work input required to operate the machine.
- The COP of a refrigeration machine is given by the formula:
COP = QL/W
- Where QL is the heat removed from the low-temperature reservoir and W is the work input required to operate the machine.
- For a reversible refrigeration machine, the COP is given by the formula:
COP = Thigh/(Thigh - Tlow)
- Where Thigh is the temperature of the heat source and Tlow is the temperature of the heat sink.
Calculation of COP for Reversible Refrigeration Machine
- For a reversible refrigeration machine with the same temperatures as the reversible engine (Tlow/Thigh = 0.7), we can calculate the COP as follows:
COP = Thigh/(Thigh - Tlow)
COP = Thigh/(Thigh - 0.7Thigh)
COP = Thigh/(0.3Thigh)
COP = 1/0.3
COP = 3.33
Conclusion
- The correct answer is option C (2.33).
- The calculation above assumes that all other conditions remain unchanged when the reversible engine is used as a refrigeration machine, which may not be realistic in practice.
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A reversible engine has ideal thermal efficiency of 30%. When it is used as a refrigeration machine with all other conditions unchanged, the coefficient of performance will bea) 3.33 b) 3.00c) 2.33 d) 1.33Correct answer is option 'C'. Can you explain this answer?
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