How it works
The parts of a refrigeration system form one closed loop that the refrigerant travels round again and again. The drawing lays the loop out flat, with the high-pressure side on the upper band and the low-pressure side on the lower.
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Round the loop
The compressor squeezes the vapor and sends it up the discharge line. In the condenser the hot vapor gives up heat and turns to liquid. The liquid line carries it to the expansion valve, where its pressure drops and it turns cold. In the evaporator it takes in heat and boils back to vapor, and the suction line returns it to the compressor.
On the liquid line
Larger systems add parts between the condenser and the expansion valve. The receiver stores liquid. The filter drier takes out moisture and dirt, the sight glass shows the liquid passing, and the solenoid valve shuts the line. The remote bulb on the suction line tells the expansion valve how far to open.
Questions and answers
What are the four main parts of a refrigeration system?
The compressor, the condenser, the expansion valve and the evaporator. The compressor and the expansion valve divide the loop into a high-pressure side and a low-pressure side.
What is the high side of a refrigeration system?
Everything from the outlet of the compressor to the expansion valve: the discharge line, the condenser, the receiver and the liquid line. The low side is the rest: the evaporator and the suction line.
What does the expansion valve do?
It meters liquid refrigerant into the evaporator. As the liquid passes through, its pressure drops sharply and part of it flashes to vapor, which chills what is left.
What is a receiver in a refrigeration system?
A tank after the condenser that collects and stores liquid refrigerant, so liquid is always ready for the expansion valve. Small systems often have none.