ABSTRACT
From an engineering point of view, carbon dioxide has been of great importance in many industrial processes and applications for several decades. It is used mainly as a solvent for supercritical uid extraction in the chemical industry and for enhanced oil well recovery. Some current developments have shown its suitability for new transcritical cycles and ecologically safe air conditioning and heat pump systems. The application of carbon dioxide as a refrigerant (R-744) in automotive air conditioning systems has grown since the pioneering works of G. Lorenzen at the end of the last century.
