Air Conditioning Cooling Process



During the air conditioning cooling process, refrigerant will flow through a piping circuit that is divided into 2 main parts: the high pressure side, and the low pressure side.


The high pressure (and high temperature) side is from the compressor outlet to the metering device, and the low pressure (and low temperature) side is from the metering device back to the compressor inlet.


The refrigerant leaves the compressor outlet as a vapor, and travels through a condenser.



Air or water that is much cooler than the refrigerant vapor will be flowing over the condenser piping, and at this stage of the air conditioning cooling process, the refrigerant will condense from a vapor to a liquid, still at a high pressure, and as it condenses, the refrigerant will release heat to the air or water flowing over the condenser.


That's why the air blowing out of the outside unit of your air conditioner is hot.


At this stage of the air conditioning cooling process, the refrigerant, now a liquid, flows through the liquid line to the metering device.

This is the end of the high pressure part of the circuit, and the low pressure side starts immediately after the metering device.


To picture the refrigerant after the metering device, picture water spraying out of a garden hose nozzle.

The full water pressure is in the hose up to the nozzle, and sprays through the nozzle because atmospheric pressure is much lower than the water pressure in the hose.


The pressure in the low side of the refrigerant circuit is similarly much lower than the high side pressure, and the image of refrigerant spraying and foaming through the metering device into the low side is fairly accurate.


As the refrigerant passes into the low pressure side of the system, it begins evaporating.

Its temperature drops as its pressure drops and it becomes cold; normally around 40 F.


The refrigerant now flows through the evaporator, where it will evaporate almost entirely to a cool vapor.


At this point in the air conditioning cooling process, relatively warm air or water flowing over the evaporator piping will cool because the heat energy it contains will flow into the relatively colder evaporating refrigerant.


That's why the air blowing out of the air conditioner in your house is cool.


The refrigerant will now carry the heat back to the compressor, absorb a little more heat when it is compressed into a high pressure, then travel to the condenser where it will release the heat it has picked up, and at this point the air conditioning cooling process will repeat itself until the space being air conditioned is cool enough to satisfy the thermostat.


You'll find more information about how the air conditoning cooling process works on our Air Conditioning and HVAC Basics, How Does Air Conditioning Work, and Air Conditioning Circuit and cycle Diagram pages,

And you might want to take a look at our free Introduction to Air Conditioning and Refrigeration and Introduction to Refrigeration Information e books, which are re-prints of several chapters from government training manuals, in pdf format.


I hope this information has helped, and please, feel free to contact us with any specific HVAC questions you might have, including questions about air conditioning on Guam, or refrigeration on Guam.

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