Low-GWP 냉매 R-1234yf의 7mm 수평평활관 내 증발열전달 및 압력강하에 관한 실험적 연구

Abstract

Refrigeration and air conditioning are used not only in modern people, but also in various industrial fields such as semiconductors and food storage. The refrigeration system absorbs heat from a low-temperature heat source using a refrigerant and discharges it to a high-temperature heat source. Therefore, the selection of refrigerant in the cycle is a very important factor. Conventionally, there have been many studies on improving the performance of a system using refrigerants with excellent thermodynamic properties. Recently, while environmental issues are attracting attention as one of the important factors, studies related to refrigerants that have less impact on the environment have been actively conducted. In this study, in the process of evaporation heat transfer in a 6.95 mm inner diameter horizontal tube of R-1234yf, a low-GWP refrigerant, the heat transfer coefficient and pressure drop according to the vapor quality were experimentally analyzed with the mass flow rate, heat flow rate, and saturation temperature as variables. The main results are as follows. As the vapor quality increased, the heat transfer coefficient increased. Also, as the mass flux, heat flux, and saturation temperature increased, the heat transfer coefficient increased. Compared with the existing refrigerant R-134a, the heat transfer coefficient of R-134a was slightly higher than that of R-1234yf. Also, as vapor quality increased, the pressure drop increased. In addition, as the mass flux increased, the pressure drop increased, and as the saturation temperature increased, the pressure drop tended to decrease. Compared with R-134a, the pressure drop of R-134a was slightly higher than that of R-1234yf. The effect of each variable on the evaporation heat transfer process is judged to be determined by the refrigerant flow pattern and thermodynamic properties. The results will provide basic data on the evaporation heat transfer of the 6.95 mm inner diameter tube of R-1234yf and help in the design of the heat exchanger using R-1234yf.