The mixed refrigerant is a mixture of several simple refrigerants in a certain proportion. In refrigeration cycles, the mixed refrigerant is generally less energy-consuming compared to its pure components. In addition, the ozone layer destruction coefficient (ODP) and the global warming coefficient (GWP) are low.
Typical mixed refrigerants include R12/R13, R22/R13, R22/R23, R134a/R23, R22/R14, R22/R23/R14, R134a/R23/R14, R600a/R23/R14, R600a/R23/R50, etc.
R600a has zero ODP and GWP, no poisoning, high latent heat of vaporization and high refrigeration efficiency. R508B is an azeotropic mixture consisting of R23 and R116, an environmentally friendly refrigerant with ODP of 0. In automatic cascade refrigeration systems, the composition ratio of mixture has a great influence on the system performance.
Ri Ju Hyok, a researcher at the Faculty of Thermal Engineering, constructed an automatic cascade refrigeration system using mixed refrigerant R600a/R508B, and analyzed its cycle characteristics, based on the thermal properties of the environmentally friendly mixed refrigerant R600a/R508B calculated by the Helmholtz energy mixture model. Then, by using Aspen Plus program, he analyzed the effect of various parameters on the cycle characteristics and optimized them.
Based on the optimization results, he built an experimental setup of an automatic cascade refrigeration system and carried out some performance experiments to confirm that the cycle characteristics analysis was relatively accurate.
You can find more information in his paper “Auto Cascade Refrigeration Process for Environmental Protection using Mixed Refrigerant R600a/R508B” in “Proceedings of KUTIC-2025”.