The major challenges in CO2 refrigeration involve the relatively high working pressures. The supercritical portion of the transcritical cycle takes place above 1,067 psia. The phase diagram for CO2 is ...

The pressure-enthalpy diagram for CO2 is shown in ... defrost pressure when hot gas defrost is used. Off-cycle pressure can be very high. This challenge can be met in several ways: A small, separate ...