In refrigeration systems, working fluid in gas state is brought from low to high temperatures and pressures using a compressor. It is then condensed by releasing heat to a moderate temperature source (for example the ambient environment). Pressure is then reduced in an expansion device turning the working fluid into a low temperature two phase mixture which evaporates in an evaporator by absorbing heat from a low temperature source (for example a refrigerator’s internal air, an electronics board, laser diode(s), pixel detector, etc.).
Similarly, the compressor can be replaced by a pump and the expansion device eliminated to achieve a pump-driven two-phase cooling system.
Refrigeration systems mechanically-driven cooling requires electrical input.