M&MRefrigeration, Inc.

 

Compressor Cooling Systems

Depending on refrigerant and operating conditions, it might be necessary to supplement the basic convection air cooling with one of the following to obtain adequate cooling of the compressor:

  • Water cooled top cover
  • Water cooled side cover including oil cooling
  • Refrigerant cooled oil cooler

Refrigerant cooled oil cooling   Water cooled side covers
(including oil cooling) and
water cooled top covers		  
Direct drive CMO 26 compressor unit


Two Stage Compressor Systems

The M&M Refrigeration two-stage compressor integrates a low pressure (LP) and a high pressure (HP) compressor in one housing. The LP cylinders compress the refrigerant gas from evaporator pressure to intermediate pressure. In an intermediate cooling system, the LP discharge gas is cooled to near saturation temperature and then drawn into the HP cylinders, where it is compressed to condensing pressure. In connection with the intermediate gas cooling, a subcooling of liquid refrigerant from the condenser can be obtained.

Two-stage compression combined with intermediate gas cooling lowers discharge temperature and the pressure ratio in the cylinders. Consequently wear and oil carry-over are reduced and the overall efficiency is improved.
   
Two stage compressor unit model TSMC 108 with intermediate cooling system C


Four different intermediate cooling systems are available

Injection interstage gas cooling
System A is a simple, inexpensive system which cools the gas by injecting liquid refrigerant into a special intermediate pipe connecting the LP discharge and the HP suction. This system does not contain liquid subcooling and efficiency improvements are limited.


Injection interstage gas and liquid cooling
System B is similar to System A, but extended with a shell and tube heat exchanger, DX feed, for liquid subcooling down to approximately 15°F above intermediate temperature. Efficiency and unit capacity are considerably improved. Liquid pressure remains at condensing pressure after subcooling. This system is mainly used for R22 and other HCFC and HFC refrigerants.



Open flash interstage cooling
System C is an open flash intermediate cooling system creating the maximum efficiency and unit capacity improvement. The liquid from the condenser is subcooled down to intermediate temperature. Liquid pressure also equals intermediate pressure, which in some applications can be a disadvantage.




Closed flash interstage cooling
System D is a closed flash intermediate cooling system creating considerable efficiency and unit capacity improvement. The liquid from the condenser is subcooled down to approximately 10°F above intermediate temperature. Liquid pressure remains at condensing pressure after subcooling. This system can be used as an alternative to System C, and is mainly used for R717.

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