Frequency drive for a 3 ton reci chiller

[jayaeros]

Hi folks,

I have a 3 ton constant speed reci chiller and would like to vary the cooling load by regulating the refrigerant flow rate. I was advised that this could be achieved by installing a frequency inverter to the compressor motor where the cooling load can be regulated by changing the motor frequency.

Is it feasible to do so? If yes, how to get it done?

Please help as i am a newcomer to this field. Your advice is highly appreciated.

Thank you
jp

[NoNickName]

Yes, it can be done, but not a job for a newcomer. Evaluations must be done for:
1) refrigerant speed in the piping at various frequencies
2) mass flow rate for motor cooling at different frequencies
3) oil return at different mass flows
4) suction pipe risers and syphons.
5) a lot of other things that I am too lazy to write down.

[jayaeros]

Hi Mr. NoNickName,

Thanks for the great info. Can you please advice me on some of the reading materials on this issue before i fully embark on this project?

Regards,
jp

[NoNickName]

Try http://books.google.com/

[SteinarN]

Factory assembled chillers normaly has pipe sizes entailing relatively high speed of flow in the suction line. Thus it is often possible to run at decreased compressor speed without any oil return problems. The same applies for the evaporator. To check this for sure you should calculate the speed in the suction line and preferably ask the manufactorer of the evaporator what is the minimum adviced gas speed at evaporator outlet.

Motor cooling is most often not a problem either. The heat development in the motor is decreased as the Hz decreases, albeit to a lesser extent. If the system is running with good cooling as is, it should not be any cooling problems vith a VSD either. It is more difficult to overheat a compressor motor for a chiller than it is for a freezer system. I'm not aware of limitations in the operating envelope for compressors run by a VSD.

What make and type is the compressor?

[jayaeros]

it's a COPELAMETIC reciprocating compressor, model MRH4-0760-TFD-200.

[jayaeros]

COPELAMETIC reciprocating compressor, model MRH4-0760-TFD-200.