Effect of Evaporator Volume on the Performance of Domestic Refrigerator

[eager]

Hello friends,

Will someone help in explaning the following .........
What will be the impact on Evaporator Inlet Temp & Evaporator Outlet Temperature if we increase or decrease volume of Evaporator by 10% approx in a domestic refrigerator

All other components & parameter are same

[nike123]

Hello friends,

Will someone help in explaning the following .........
What will be the impact on Evaporator Inlet Temp & Evaporator Outlet Temperature if we increase or decrease volume of Evaporator by 10% approx in a domestic refrigerator

All other components & parameter are same

Do you mean evaporator active surface increase of 10%?

[eager]

Do you mean evaporator active surface increase of 10%?
This is a Roll Bond Panel type Evaporator, there is no change in surface area of panel, only change is in the internal volume of passage for refrigerant

[Brian_UK]

I would suggest that the cooling capacity will decrease.

[eager]

I would suggest that the cooling capacity will decrease.
Thanks Brian

But it will be better if i may know the logic behind this

[US Iceman]

What will be the impact on Evaporator Inlet Temp & Evaporator Outlet Temperature if we increase or decrease volume of Evaporator by 10% approx in a domestic refrigerator


May I ask the reason for this question? If you change the internal volume of the refrigerant circuits in the evaporator, what do you expect to happen?

[Brian_UK]

Thanks Brian

But it will be better if i may know the logic behind thisVery simple logic really - less pipework for refrigerant means less cooling surface.

[eager]

May I ask the reason for this question? If you change the internal volume of the refrigerant circuits in the evaporator, what do you expect to happen?
Well, this is because Evaporator is from some supplier other than the original Supplier & its volume is more than the original one

[wambat]

All other components & parameter are same
Of course this must apply otherwise all bets are off

[US Iceman]

Since we do not have a lot of information to review here are some basic points to be aware of:

a) The flow path(s) of the refrigerant through the evaporator are called circuits. A circuit is the complete length of this flow path. There may be more than one in any evaporator. However, since you said this is a domestic refrigerator I would assume there is only one circuit with a single cap tube feeding the evaporator circuit.

b) If the internal volume of the circuit is greater than the original one I would again assume the circuit diameter is larger (or it could be longer). This can affect either pressure loss or heat transfer capacity. Either may cause a loss of capacity.

c) The capacity of the new evaporator should be available from the new manufacturer. They should state the pressure loss of the evaporator circuit and the overall heat transfer capacity also. If the new evaporator has performance and pressure loss characteristics different from the original then the system performance will be different even with the same compressor, condenser, cap tube, etc.

The only way to be 100% sure the new evaporator will perform as desired is to test the refrigerator with the replacement evaporator.

[eager]

Thanks for your answer

[rollbond]

It will depend on the difference of internal volume between the new evaporator and the previous one.
Due to manufacturing constraints, the tolerance of internal volume of a roll bond evaporator is most of time +/-10%. This tolerance has been accepted by the refrigerators manufacturers for years and the impact on the performances is low.

Of course, if the volume is out of this tolerance you should ask to your supplier to decrease the internal volume for the next order.

[amitsaxena]

The effect of internal volume on ref. performance is as

1. Once you reduce the internal volume and keep the secondary area same then, the superheat of eva increases/no change, but during practical situation the evaporator temperature go up, means superheat increases, hence reduces the cooling capacity.

2.If you want to use a big evaporator or say higher in internal volume, then there is not much change in Superheat. also, if you dont change the charge (Refrigerant) quantity, then no change in cooling performance but if you slightly increase the charge qty as well then you get better cooling performance.