LAUSR

Abstract As the use of semiconductors in industrial site increases, research on ultra-low refrigerators is required to increase the life and quality of the semiconductors. While various types of refrigerators exist, Joule–Thomson refrigeration with the mixed refrigerant is preferred because of its compactness and stability. The performance of Joule–Thomson refrigeration with mixed refrigerants is based on the mixing ratio of the refrigerants. Therefore, in this study, three kinds of refrigerant groups, namely high boiling point (R-600a), middle boiling point (R-23), and low boiling point (R-14), are used to examine the change in the system’s performance according to the composition ratio of each refrigerant. The results indicate that as the ratio of the high boiling point refrigerant increases, the discharge, and suction temperature decrease. As the ratio of the middle boiling point refrigerant increases, the condensation pressure decreases, and thus, the inlet temperature of the expansion valve also decreases. As the ratio of the low boiling point refrigerant increases, the cooling capacity tends to increase.