In this study, We aim to provide design data for a low-temperature refrigeration system to select operating conditions for predicting maximum performance of an eco-friendly binary refrigeration system based on changing operating conditions The operating variables considered in this paper are evaporating temperature, condensing temperature, superheating degree, subcooling degree, and compression efficiency. The main results are summarized as follows: In the low temperature range of -50℃ to -30℃, the COP of the system increased as the evaporating temperature and subcooling degree of the binary refrigeration system for R744-R717 increased, but the COP decreased as the condensing temperature and superheating degree increased. It was confirmed that factors such as superheating, subcooling, condensing temperature, evaporating temperature, cascade temperature difference, and compression efficiency affect the performance coefficient of the binary refrigeration cycle for R744 and R717, and it was found that each of these factors has a cascade evaporating temperature that maximizes the performance of the binary refrigeration cycle.

Abstract
1. 서 론
2. 성능 분석
3. 결과 및 고찰
    3.1 증발온도의 영향
    3.2 과열도의 영향
    3.3 응축온도의 영향
    3.4 과냉각도의 영향
    3.5 압축효율의 영향
    3.6 캐스케이드 열교환기 온도차의 영향
    3.7 성능분석법 제안
4. 결 론
References

• 천상철(Professor, Dept. of Smart Farm Agricultural and Fisheries Welfare, Hwashin Cyber University) | Sang-Cheol Cheon Corresponding author