SAMSA, Inc. Refrigeration

The refrigeration cycle consists of four major components. The compressor, condenser,thermal expansion valve and the evaporator. A system is charged with a gas whether it be R12, R22, R502 makes no difference at this point. Lets assume the above system uses R22. We also need to know that the condenser is used to reject heat and the evaporator is used to gain heat. Lets start at the compressor.

The compressor is designed to compress gas as a low pressure superheated gas to a high pressure superheated gas. You ask. "What is a superheated gas!" Well for now you need to know that a superheat gas, is a gas with no liquid present that holds more heat than it's saturated value.

Once this superheated gas is compressed it is sent to the condenser through the discharge line where air or water is used, depending on the type of condenser, to condense the high pressure superheated gas into a high pressure liquid. This process is accomplished when the high pressure superheated gas gives up it's heat through the condenser or heatexchange and condenses into a liquid. Liquid is then pushed towards the thermal expansion valve.

The thermal expansion valve is nothing more than a metering device that reduces the liquid pressure by creating a pressure drop which causes the liquid to boil into a saturated gas. Saturated gas is a gas where liquid and gas are present at the same time. Because of the pressure drop and the boiling effect of liquid refrigerant this saturated gas becomes very cold as it heads into the evaporator.

Now imagine sitting at your desk working on a 90 degree F. summer day (bummer I'd rather be on the boat) and your office is a pleasant 72 degrees F. That is accomplished when you use SAMSA, Inc. as your service provider and when that saturated liquid hits the evaporator. Warm building air or water (if a chiller) passes through one side of a heat exchanger and the saturated liquid on the other side. A basic law of physics is heat moves towards cold. The warm building air gives up it's heat to the cold saturated liquid which is turning into a superheated gas as it passes through the evaporator. That's right. The cold gas is picking up more heat in the evaporator than its corresponding pressure / temperature saturated value. Once we have achieved this value the gas may leave the evaporator through the suction line and back to the compressor to chase another BTU.

Now you have a basic understanding of the refrigeration cycle. For those of you that have mastered this cycle, please understand that this cycle has been kept basic for the purpose of what goes on where and when, and was never intended to create superb refrigeration engineers.