Mechanical Engineering - Heat Transfer, Refrigeration and Air Conditioning - Discussion

Discussion Forum : Heat Transfer, Refrigeration and Air Conditioning - Section 6 (Q.No. 1)
1.
A condenser of refrigeration system rejects heat at the rate of 120 kW, while its compressor consumes a power of 30 kW. The coefficient of performance of the system will be
1/4
1/3
3
4
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
25 comments Page 2 of 3.

Lalit Kumar said:   7 years ago
120-30 = 90.
Cop=90/30=3 => ans.

Prabhat swain said:   7 years ago
@Rakesh Thakur.

Output/input not COP.
This is efficiency.

COP is the reciprocal of efficiency.

Prabhat swain said:   7 years ago
This question also came in Isro exam.

And answer key of ISRo shows the correct answer is 3.

So, the answer is 3.

Anand Kumar Singh said:   7 years ago
3 is the correct answer.

Manash said:   7 years ago
The answer is (c) 3.

Yatendra said:   7 years ago
Yes, I agree cop = 3.

Rakesh thakur said:   7 years ago
cop = out put /input.
energy out /input.
120/30.

Lucky Patel said:   7 years ago
Answer should be 3.

Because the ratio of condenser heat rejection to power consumption is called co efficient of performance for the heat pump. And we have to find cop of refrigerator thus from equation
COP hp =COPr + 1.
Cop for refrigerator 3.

Mehul J said:   7 years ago
Heat rejected = Heat taken from Evaporator + heat rejected from compressor.

Here heat Rejected is given as summation of RE+ W ( Compressor).
Now COP = RE/Work.
= 120 - 30/30 = 3.

Ajith said:   8 years ago
C.O.P = heat/workdone,

=> 120/30,

=> 4.


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