The critical temperature of CO2 is very low (31.1℃). Therefore, when it is used in heat pump circulation, the temperature must be higher than the critical temperature. Under the supercriticality condition, CO2 is not saturated, and thanks to its large specific heat capacity, high coefficient of thermal conductivity and small coefficient of dynamic viscosity, it is easy for CO2 to flow and achieve heat exchange. As a result, the pipeline and heat exchanger size can be reduced, contributing to a more compact system.

The built-in three-way valve supports switch between direct mode and recycle mode.