4. Open evolution system related to PAC

These systems, for industrial use, derive from heat pumps by opening up the cycle on either side of the expansion valve, which is generally omitted. In addition, the evaporator and condenser are grouped together in a unit that produces steam on the evaporator side, largely by condensing the same steam that has been compressed.

The compression device can be a compressor (mechanical energy input) or an ejector (fluid and steam energy input).

The fact that the same fluid often acts as both a heat transfer medium and a heat source means that these systems perform well.