CO2 refrigeration uses carbon dioxide (R-744) as the working fluid in refrigeration systems, operating in either subcritical or transcritical cycles depending on application temperature requirements. CO2 offers zero ozone depletion potential, minimal global warming impact, and excellent thermodynamic properties. Its adoption has grown significantly in commercial refrigeration, heat pumps, and industrial applications over the past decade.
Technical Details
CO2 operates at substantially higher pressures than traditional refrigerants, with critical point at 31.1°C and 73.8 bar. Subcritical systems operate below these limits for low-temperature applications, while transcritical cycles intentionally exceed the critical point for improved efficiency at moderate temperatures. Saturation pressure at 0°C reaches 34.9 bar, requiring pressure vessels and components rated for 100-150 bar safety margins. System charge densities are 2-3 times higher than HFC-404A, enabling compact heat exchanger designs.
Advantages
CO2 systems achieve 15-25% better efficiency in heat pump applications compared to conventional refrigerants. Zero GWP (Global Warming Potential) aligns with EU F-Gas regulations limiting refrigerant emissions. Natural refrigerant properties improve environmental compliance and reduce long-term operating restrictions. Component standardization is improving rapidly as manufacturers scale production across Europe and North America.