Next you will need to decide the Compressor you want to use. The 2 main
things to note will be the Horsepower and the oil used. Normally on the
compressor, the refrigerant it is made for will be stated, and sometimes the oil
that is inside will be stated as well. For example, compressors made to run R22
usually have mineral oil inside it. This oil will mix with R22 and R290
(Propane) but will not mix with R134A, R404A and R507. Thus, to run R134A, R404A
and R507 with the compressor, you will either need to change out the oil or run
it mixed with R290 (Propane) You can however run R22 with R404A or R134A
compressors as they contain POE oil which is miscible with R22.

For this project, I used an old 1/3 Horsepower Rotary compressor made for
R134A for this project. I salvaged it off an old Aquarium Chiller I got from the
scrapyard.

54 Phase Change Basics 2: Setting Up a System

55 Phase Change Basics 2: Setting Up a System

As seen in the picture, the discharge line is the pipe from the the
refrigerant is pumped out and the suction line is where the refrigerant is
sucked back into the compressor. It is made for R134A but I was planning to use
it with R22. When you are going to use a higher-pressured refrigerant than the
one the compressor was specified for, it is putting more stress on your
compressor so please take note. For a direct-die cooling system, a compressor as
small as 1/4 HP will be fine but 1/3 HP will work good.