비가연성 5성분계 혼합 냉매를 이용한 –100℃ 줄-톰슨 냉동기에 관한 연구

Abstract

In addition to the recent growth and competition in the semiconductor industry, investment and interest in Korea have grown along with the United States and Taiwan. This investment and interest in semiconductor production lines is inevitable, and the chiller, one of the temperature control systems used in the semiconductor manufacturing process, is important that the performance of chiller enhancing. There are two types of refrigeration method applied with the chiller that using pure refrigerant, and using mixed refrigerant in Joule-Thomson cooler. This study is on Joule-Thomson cooler using mixed refrigerant. In Particular, non-flammable refrigerant is used to secure stability in the operating media, rather than flammable refrigerant. In the case of mixed refrigerant, the selection of the composition directly affects performance. But many studies show that it is limited to certain conditions. Thus, in many conditions, the composition ratio, which was optimized by thermodynamically optimizing, was applied to the actual cooler and compared. The experimental conditions were using 2.24 kW(3 HP) scroll compressor, ambient temperature was 288 K and evaporative temperature is –100℃(173 K). The set pressure is 0.20 MPa and 0.25 MPa in the low-pressure stream and 2.0 MPa and 2.5 MPa in the high-pressure stream. Refrigerants were selected at intervals of around 30 ~ 40℃ on a NBP(Normal Boiling Point) basis, and R-245fa, R-134a, R-404A, R-116, R-23 and R-14 were used in this study. The experiment was conducted with a total of 13 cases and compared design value with experimental value. In particular, when the pressure of low- pressure stream was 0.25 MPa and the high-pressure stream was 2.5 MPa, among the cases using R-134a, R-404A, R-116, R-23, R-14, the design and experimental values matched more than 70% and cooling capacity was 200 W. Analysis with actual calculated enthalpy showed high exergy efficiency by a constant enthalpy difference between the 2 streams. However, R-245fa had the best performance in the design value, but the targe temperature was not reached due to the compressor discharge temperature and the liquid back. To this end, it seems necessary to study the bubble point and 2 phase flow of mixed refrigerant, and gas analysis through gas chromatograph.