Refrigeration with Air Conditioning Compressors

[Samarjit Sen]

What would be your comments in using Scroll Compressors suitable for Air Conditioning application for a refrigeration application where the evaporative temperature is to be maintained at - 8 Deg. C with a condensing temperature of 50 Deg. C The Relative Humidity inside the room has to be maintained at 95 to 98%. Would using Semi Hermetic Compressors suitable for refrigeration duty would be more suitable ?

This is something similar to a thread posted in this forum some time back about air conditioning condensing unit being installed in Wlak In Freezers.

[winfred.dela]

Scrolls for aircon and refrigeration duty does not vary much.
The best thing is to find a performance chart of the models you intend to use.
Scrolls have advance a lot in few years that they are already used in freezers.
I favor using a recip hermetic compressor for below zero and aircon scrolls, I use only up to 0C evap temp.

[Samarjit Sen]

The scroll about which I am talking is rated for air conditioning applications and the required evap. temp. is - 8 Deg. C. There are scrolls for refrigeration duty which has a much lower evap. temp. This particular model is outside the envelope.

[winfred.dela]

As i have mentioned in my previous post: Aircon & Refrigeration Scrolls does'nt vary much.
So, you can try.

As I have done with some recip & scroll models.
Some Aircon models are OK some are not.

Taking a hard look in the complete chart of each model will help you decide.

[mickandlee]

For the same size of compressor running at the same speed when operating at low temperature produces less duty and power absorbed that when operating at higher (air conditioning) conditions.

Some hermetic compressor manufacturers, mainly for for cost cutting reasons, manufacture low temp units with smaller motors.

Therefor it is often possible to use an air conditioning compressor on low temp work but not the otherway round.

Air conditioning water chiller manufactures sometimes have different motors for water cooled and air cooled compressor units.

Mick

[taz24]

The scroll about which I am talking is rated for air conditioning applications and the required evap. temp. is - 8 Deg. C. There are scrolls for refrigeration duty which has a much lower evap. temp. This particular model is outside the envelope.

Most scroll's will opereate with a return temp of about -5c to -10c

Cheers taz.

[Sridhar1312]

Scroll for AC application cannot be used for Refrigearion as if we have to get minus 8 degree C the evaporating temperature shall be minus 16 degree C and the components as well as coils as it is may not be suitable as teh coil will get frost.
In addition to the above compression ratio goes higher consequently the cpmpressor gets strained and the refrigerant will be highly super heated.
Even expansion valve/device need to be changed.