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desA
25-10-2010, 05:30 AM
I have an application in a very small system, where the evaporator is located above a rotary compressor, with integral suction accumulator. The system contains a capillary tube expansion device.

I would like to change the compressor to a hermetic, refrigerator-type, which does not have a suction accumulator. My concern is how to manage potential liquid flood-back from the evaporator & droplet carryover.

I have looked into small suction line accumulators, but these are very difficult to find, at the capacity of the system under consideration. Space is also at a premium.

I'd appreciate advice & applied wisdom on how to achieve this system change in a safe manner, with maximum compressor protection afforded. Thanks so much for your help.

Peter_1
25-10-2010, 06:18 AM
Most rotaries have a SA mounted on it because they could be used widely an many times in reversible systems. But, SA's are not always needed.

I thought that many manufactures have a table where you can read max charge a compressor in a cap system may have.
The sump of a hermetic compressor can hold also some refrigerant.

I don't see much troubles with not adding one.
In the worst case, you always can add a small crankcase heater and make sure you have an oil siphon after the evaporator so that liquid can't flow back.

If it was me, I shouldn't worry to much and leave the SA. What's the new compressor model and refrigerant charge?

Or you can always find a small SA in many small domestic freezers on the scrapyard.

I'm sure, all things you certainly knew but hadn't think about it or you just needed a confirmation of your ideas.

desA
25-10-2010, 07:30 AM
Thanks so much Peter.


Peter_1:
If it was me, I shouldn't worry to much and leave the SA. What's the new compressor model and refrigerant charge?

An example here would be the Danfoss SC12G, with max refrigerant charge of 1.3kg. The final system charge will be around 600g, or less.



I'm sure, all things you certainly knew but hadn't think about it or you just needed a confirmation of your ideas.

:D

Peter_1
25-10-2010, 08:57 AM
http://www.ra.danfoss.com/TechnicalInfo/Literature/Manuals/06/SC12G_R134a_220V_50Hz_08-03_Cd44p402.pdf

SC12G,n max charge, 1300 grams, so no problem at all.

desA
25-10-2010, 09:39 AM
^ Thanks so much, Peter. I always like to quadruple-check everything before cutting metal.

:)

Aik
25-10-2010, 11:44 AM
Also if there is possibility stop with pump-down...