R410A compressor - capacity adjustment

[Stans]

I am looking for a compressor suitable for R-410A with a capacity of up to 5 TR or larger. I need to be able to adjust the capacity from 1 TR to its max. Capland's scroll compressors do not allow such capacity adjustment. Also the compressors must be available in N. America. I know that A6 compressors are used in transportation refrigeration but with use of R-134A and have a capacity of only up to 2.5 TR. Can somebody advise on this?

[NoNickName]

Inverter plus hot gas bypass. Any 5TR compressor would do the job

[winfred.dela]

Hi NoName,
Thanks for the info.
I was made to understand by VRV suppliers that the compressor with inverter is different from the old commercial models.
I thought the compressors for VRV have special oil pump system.
Is there minimum and maximum RPM needed for adequate oil circulation inside the compressor?
Maybe I should try assembling one.
Any additional tips from all you guys?

[NoNickName]

A std scroll would go down as much as 25Hz and as high as 60Hz (provided the std frequency is 50Hz).
A special one would accept 15-80Hz, but I wouldn't dare.
Still 15Hz in a 50Hz 5TR compressor equates to 1.5TR, not 1TR.

[winfred.dela]

Scroll model is best then, how about recip or rotary?
Since we have here 60hz, I can then go as low as 30 hz and as much as 72hz.
A 4HP/60hz compressor can then operate from 2HP to 5HP.
Ok thanks for the tip.

[NoNickName]

Fluid dynamics of recips is not completely satisfactory with rotational speed variation. No idea on rotaries.

[Stans]

Thanks to both for discussion. It looks that the only option I have at the moment is to use two A6 compressors in parallel. They are solidly build and should be able to withstand the higher pressure required for R-410A as compared to R-134A for which they are typically rated. Also, they allow access to their crankshaft basin for providing better oil level control.

Scroll compressor manufacturer doesn't advice change in the RPM due to potential oil problems.

Would still appreciate further comments.

[Mauro]

Hi Me it seems that copeland has the digital compressor scroll that must take care of its necessity, however the cost must be high, at least in Brazil is high