This describes the basic layout of a single stage Phase change cooling system.


Image from this forum thread at Pimprig; corrected with info provided by Jort thanks!

It starts with the compressor. As the name states this is what compresses the refrigerant. At this point it is a gas and that's what it is designed to pump.

From here it pumps to the condenser, the top side of the condenser to be exact. By cooling the gas and compressing it, it will turn into the liquid needed to create the Phase-change. Out of the bottom of the condenser and into a filter is where the flow goes next. Out of the filter there is a small diameter copper line called the capillary tube or capline. This is where the tuning of the system is done. The length and diameter is critical for the temperature of the evaporator.

The Evaporator is the equivalent to the CPU block in a water cooling system. It is what is mounted to the CPU or GPU. There are many different designs and it acts similar to its H20 counterpart, to more surface area that can be exposed to the refrigerant the better.

This is also where the Phase-Change occurs. Liquid refrigerant makes its way to a larger volume of space and changes its phase from a liquid to a vapor, or boils off. Refrigerant boils at a very low temperate and that is the main difference between the dozens of types of refrigerants (R134/R404A/R504/etc). During this change it sucks up the heat and releases its cold.

The return line or suction line as it is referred to, has negative pressure in it. It is caused by the compressor pressurizing the high side, creating a low side in the return line, because the system is sealed. The refrigerant is now back in a gas form and is cycled again through the system.