Refrigerant mixture research work done by the authors was reported on frequently between 1977 and 1980. Since then further research work has been carried out concerning both the determination of the thermophysical data of refrigerant mixtures with and without oil and also the application of refrigerant mixtures for various refrigerant cycles.

The results of this work are dealt with in this paper as a report on the current state of the art. The results deal in particular with refrigerant mixtures R-12/R-114 and R-22/R-114 with regard to their thermodynamic data. Their application in heat pumps is also considered. Results of thermophysical data experiments as well as mixture application in refrigerating systems and heat pumps are given with regard to the improvement of COP and capacity. The possibility of loss-free continuous capacity control is indicated by experimental results. Further calculations for the use of a mixture cascade are dealt with and compared with refrigerating systems working with pure refrigerants.