Low-GWP 혼합냉매를 적용한 -100°C 캐스케이드 냉동시스템의 성능 특성 연구

Abstract

The rapid growth of the semiconductor industry and the increasing aspect ratio of advanced etching processes have led to the accumulation of by-products in narrow etching areas, causing a decrease in etching rates. To address this issue, Cryogenic Etch technology has been introduced, which operates at temperatures below –100°C and lowers chemical reactivity, thus enhancing etching rates. In these cryogenic processes, improving the efficiency of the low-temperature chiller, which plays a critical role, is essential. While the use of high Global warming potential(GWP) refrigerants is regulated in most refrigeration and heating applications, Ultra-low temperature(ULT) systems are not included in these regulations. Research on replacing traditional refrigerants such as R-23, R-14, and R-508B with low-GWP refrigerants for ULT applications remains limited. This study proposes a method to enhance the performance of Cascade Refrigeration Systems (CRS) operating below –100°C. Unlike previous studies, this research does not fix the LTC evaporating pressure or the condensation and evaporation temperatures of the cascade heat exchangers, but instead analyzes the system's performance characteristics, including COP and exergy, by varying the mass fraction of mixed refrigerants (MR) in 1% increments. Simulation results showed that the maximum COP of 0.62 was achieved with the optimal MR composition, while the exergy destruction was the lowest at 5.18 kW for the same MR composition. The GWP was found to be 50.76, indicating excellent stability and environmental friendliness. Furthermore, reducing the temperature difference in the cascade heat exchanger (CHX) yielded more favorable results in terms of energy and exergy. This study demonstrates the feasibility of applying low-GWP MR in ULT CRS systems, providing critical data to maximize the efficiency of chillers used in cryogenic etching processes. It is expected to contribute to the development of sustainable low-temperature cooling solutions in the semiconductor industry and play a key role in enhancing the energy efficiency of environmentally friendly ULT refrigeration research in the future.