Mechanical Engineering - Heat Transfer, Refrigeration and Air Conditioning - Discussion
Discussion Forum : Heat Transfer, Refrigeration and Air Conditioning - Section 1 (Q.No. 5)
5.
In a refrigerating machine, heat rejected is __________ heat absorbed.
Discussion:
17 comments Page 1 of 2.
Amangpm said:
1 decade ago
For extracting heat from low temperature to high temperature. We need to input some power or work. As in case of 2nd law of thermodynamics.
We have to maintain lower temperature for cooling purpose and have to extract heat from lower temperature. And reject it to higher temperature level.
We have to maintain lower temperature for cooling purpose and have to extract heat from lower temperature. And reject it to higher temperature level.
(1)
Sanjeeva said:
7 years ago
The refrigerant available in the form of vapour. If there is no heat rejection is does not takes place in condenser the vapour does not produce any refrigeration effect. That's why we reject the heat more than absorption.
Sekhar said:
1 decade ago
In VCRS heat rejected from condenser to surrounding fluid (Q1) is summation of work given to the compressor (W1) and heat extracted (Q2) from the space which is to be cooled.
Q1= (W1) + (Q2).
Q1= (W1) + (Q2).
Rahul M said:
6 years ago
Heat rejected from a refrigerator is always greater than heat absorption, because of not only the heat from the substance but also the heat generated during the working of the compressor.
(1)
Mohnesh said:
1 decade ago
In refrigeration heat rejected is more than heat absorbed because its function is cooling a substance so for cooling we used reverse cycle.
Lucky said:
10 years ago
This is because, some mechanical work also to be done by machine to reject the absorbed heat from a lower temperature to high temperature.
(1)
Huma said:
6 years ago
Because the heat rejected also contains the miscellaneous heat that is produced by the refrigerators part, along with the heat absorbed.
(1)
Naeem said:
7 years ago
Here the work done can't be a negative value in COP formula, i.e. if Qh-QL is -ve value then COP= -ve value, which is not possible.
(1)
Raju said:
8 years ago
Answer is C because heat is rejected always at higher temperatures that's why we require the more work to reject temp.
(1)
Raj said:
1 decade ago
For cooling purpose it is essential that heat rejected is more than heat absorbed.
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