Compressors
The job of a refrigeration compressor is to compress vapour and circulate refrigerant around the sealed system.
We need it to cycle refrigerant around the system as this process is necessary to maintain the cooling effect over extended periods of time. To simplify things further the compressor is like the refrigerator's heart beat pushing refrigerant around its circuit.
The compressor needs to compress the vapour that has boiled off from the evaporator and to increase its pressure. This increased pressure helps force the vapour back into liquid form via the condensor.
From here the liquid can then enter the metering device, then on to the evaporator. It can now begin to boil in the low pressure environment absorbing latent heat energy from the refrigerated space.
Types of compressor.
Most cooling systems in use today rely on reciprocating piston-type compressors which are manufactured in three types:
Reciprocating Compressors
This hermetic type of compressor is most seen on small to medium sized refrigeration systems. It is the type of compressor you will see on your household refrigerator. They come in three common types:
Hermetic - this compressor is contained in a steel case, typically used in household refrigerators, air conditioning units and smaller industial systems.
This type of motor operates in an atmosphere of the refrigerant.
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Semi-hermetic - This type of compressor is contained in a metal case but major parts can be accessed such as valves.
This type of compressor is usuall inatalled where frequent maintanance to the compressor is desirable.
Open - This Type of compressor is very industrial and often used for ammonia refrigeration. Very useful if routine motor maintenance is required as the motor can be worked on often without removing refrigeration from the system.
Also a complete replacement compressor is possible without shutting down the plant.
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