R744 CO₂ in heat pumps: what is the transcritical cycle

R744 is carbon dioxide and is used in special heat pumps, particularly when high DHW temperatures are required.

High pressures

CO₂ operates at much higher pressures than many conventional refrigerants.

Transcritical operation

Under several conditions, the refrigerant rejects heat above its critical point, and there is no classic condensation.

Gas cooler

In place of a conventional condenser, a gas cooler is used for heat rejection.

Applications

R744 is particularly interesting for high-temperature DHW production.