Experimental study on the evaporation heat transfer characteristics of R-1234yf with a variation in tube diameter
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Freon-based refrigerants, which are excellent in terms of efficiency and stability, have a high global warming potential; therefore, Hydrofluoroolefin(HFO)-based refrigerants are attracting interest as alternative refrigerants for refrigeration and air-conditioning systems. In particular, R-1234yf, which has similar thermal properties to R-134a but has less impact on the environment, is being considered as an alternative refrigerant. Therefore, in this study, an experimental study on evaporation heat transfer characteristics was conducted using R-1234yf in horizontal tubes with inner diameters of 3.7, 5.3, and 6.8 mm. The evaporation heat transfer characteristics were identified at a saturation temperature of 5–15 ℃, mass flux of 200–500 kg/m2s, heat flux of 5–15 kW/m2, and quality of 0–1. The effects of changes in quality, mass flux, heat flux, saturation temperature, and tube diameter on the evaporation heat transfer coefficient were revealed, and the evaporation heat transfer coefficients of R-1234yf and R-134a were compared. As the heat flux increased, the evaporation heat transfer coefficient increased. Regardless of the mass flux and saturation temperature, the smaller the tube diameter in the entire quality region, the higher the heat transfer coefficient was. Additionally, the average heat transfer coefficient of R-134a was observed to be higher than that of R-1234yf.
Abstract
Freon-based refrigerants, which are excellent in terms of efficiency and stability, have a high global warming potential; therefore, Hydrofluoroolefin(HFO)-based refrigerants are attracting interest as alternative refrigerants for refrigeration and air-conditioning systems. In particular, R-1234yf, which has similar thermal properties to R-134a but has less impact on the environment, is being considered as an alternative refrigerant. Therefore, in this study, an experimental study on evaporation heat transfer characteristics was conducted using R-1234yf in horizontal tubes with inner diameters of 3.7, 5.3, and 6.8 mm. The evaporation heat transfer characteristics were identified at a saturation temperature of 5–15 ℃, mass flux of 200–500 kg/m2s, heat flux of 5–15 kW/m2, and quality of 0–1. The effects of changes in quality, mass flux, heat flux, saturation temperature, and tube diameter on the evaporation heat transfer coefficient were revealed, and the evaporation heat transfer coefficients of R-1234yf and R-134a were compared. As the heat flux increased, the evaporation heat transfer coefficient increased. Regardless of the mass flux and saturation temperature, the smaller the tube diameter in the entire quality region, the higher the heat transfer coefficient was. Additionally, the average heat transfer coefficient of R-134a was observed to be higher than that of R-1234yf.
참고문헌 (9)
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