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


The lowest temperature during the cycle in a vapour compression system occurs after

[A]. compression
[B]. expansion
[C]. condensation
[D]. evaporation

Answer: Option D


No answer description available for this question.

Venkat Sri said: (Jul 23, 2014)  
In general the lowest temperature in any refrigeration cycle is occur after the EXPANSION process only. But in the answer mentioned that is after evaporation.

In the process of evaporation the refrigerant collect latent heat from bodies.

Faisal Ahmad said: (Nov 4, 2014)  
I think Mr Venkat Sri is right the lowest temperature in refrigeration cycle occurs after Expansion or Throttling.

Pranesh said: (Nov 24, 2014)  
The temperature after expansion and after evaporation remains same since after expansion, evaporation occurs at constant temperature.

Punit Vyas said: (Mar 5, 2015)  

But during evaporation refrigerant takes latent heat so temp will be raised. So answer will be expansion.

Asif Ahamed said: (Aug 21, 2016)  
In VCR system if we observed in H-S and T-S diagram lowest temperature point is point 4 i.e. after expansion. So the answer is after expansion because after evaporation the condition of refrigerant is saturated vapor then how will be the lowest temperature after evaporation?

Dhanendra said: (Aug 22, 2016)  
During evaporation temperature remain constant.

During latent heat is added.

So, both are correct.

Suresh said: (Sep 4, 2016)  
Both answer are correct.

As during evaporation latent heat is added.

Krishan Kaushik said: (Oct 18, 2016)  
Lowest temperature is caused after the condenser.

Sumesh said: (Jan 30, 2017)  
Right answer is option B. Expansion.

Chacoboy said: (Jun 28, 2017)  
Due to sudden drop of pressure at expansion the temperature also drops but after expansion latin heat is received during the evaporation so correct answer is Expansion.

Bhavi said: (Aug 20, 2017)  
It's after expansion.

Nikunj Miyani said: (Nov 23, 2017)  
Both B and D answers are right. Because in evaporation, Refrigerant Absorbs latent heat at constant pressure. Only state changes, not temperature.

Deepak Rathva said: (Apr 6, 2018)  
After expansion is right.
But evaporation is also done at constant temperature in VCR.

So, the Answer is 1. After expansion & 2. During evaporation.

Sohel said: (May 10, 2018)  
D is right because in evaporator latent heat is transfer so the temperature remains same only phase change occurs.

Jigs said: (Mar 4, 2019)  
Yes, you are right @Nikunj Miyani.

Kishan Gohil said: (May 2, 2019)  
Lowest temperature during the cycle in a vapour compression system occurs after condensation or throttling.

Arun said: (Jun 21, 2019)  
After"Expansion" Low temperature occurs.

After"evaporation " Low temperature to normal temperature because of heat addition occur during evaporation. So, answer is option (A).

Ankit Kumar said: (Jul 25, 2019)  
Yes, the temperature is constant during evaporation but within the dome, when constant pressure line crosses the dome then he goes in the superheated region and here temp is not constant, so the most appropriate answer is after expansion.

Rajesh Roy said: (Sep 13, 2019)  
A/c to T-S diagram, lowest temperature should be after expansion or throttling.

Mara said: (Aug 30, 2020)  
After expansion, before entering to evaporator the ref temp may go down to -15 deg. C.

Anomie said: (Oct 13, 2020)  
It's after EXPANSION.

Vinay said: (Nov 6, 2020)  
It's after EXPANSION.

Ksrtc said: (Feb 11, 2021)  
After expansion, before entering to evaporator the ref temp may go down to -15 °C.

Omkar said: (Jan 10, 2022)  
@Punit Vyas.

After taking latent heat, the enthalpy is increased but temperature remains same.

Kuldeep Gupta said: (May 25, 2022)  
In actual, at the end of the evaporator, we always get superheated vapor which is obviously greater than the temp of the refrigerant after expansion.

Therefore the temp of the refrigerant is lowest after expansion. So, option B is correct.

Post your comments here:

Name *:

Email   : (optional)

» Your comments will be displayed only after manual approval.