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


In a refrigerating machine, heat rejected is __________ heat absorbed.

[A]. equal to
[B]. less than
[C]. greater than

Answer: Option C


No answer description available for this question.

Raj said: (Jul 12, 2013)  
For cooling purpose it is essential that heat rejected is more than heat absorbed.

Siva said: (Aug 29, 2013)  
Heat absorbed + work done in it = heat rejected. So that's the matter.

Mohnesh said: (Aug 9, 2014)  
In refrigeration heat rejected is more than heat absorbed because its function is cooling a substance so for cooling we used reverse cycle.

Ahmed said: (Aug 30, 2014)  
Yes C, Because Heat absorbed + work done in it = heat rejected.

Ankit Tamrkar said: (Dec 5, 2014)  
Ya, the answer will be C, because, heat absorbed + work done = heat rejected.

Sagar Naikar said: (Apr 16, 2015)  
Yes, Work done = Heat absorbed-Heat rejected.

Sekhar said: (Sep 3, 2015)  
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).

Amangpm said: (Sep 5, 2015)  
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.

Lucky said: (Oct 13, 2015)  
This is because, some mechanical work also to be done by machine to reject the absorbed heat from a lower temperature to high temperature.

Amar said: (Jan 9, 2017)  
Yeah! answer C is Right. Agree.

Raju said: (Nov 3, 2017)  
Answer is C because heat is rejected always at higher temperatures that's why we require the more work to reject temp.

Vishal said: (Jan 31, 2018)  
Always energy is released higher form to lower form.

Sanjeeva said: (Jul 5, 2018)  
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.

Naeem said: (Nov 9, 2018)  
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.

Rahul M said: (Sep 20, 2019)  
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.

Huma said: (Oct 20, 2019)  
Because the heat rejected also contains the miscellaneous heat that is produced by the refrigerators part, along with the heat absorbed.

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