| Summary: | 碩士 === 和春技術學院 === 電機工程研究所 === 107 === This paper mainly establishes the dropout mode of the three-dimensional turbulent flow field of the double-casing heat exchanger, discusses the heat transfer efficiency of the R134a refrigerant in the heat exchanger, and analyzes whether the heat exchanger has natural convection with or without air radiation. Calculate the temperature change at the outlet side of the refrigerant. The results show that when there is air convection without considering heat radiation, the R134a refrigerant in the front, middle and back sections has a larger temperature drop than the airless convection, and the closer to the outer casing side, the larger the cooling rate is, the biggest difference It is located at the inner wall of the outer tube of the rear section, with a temperature difference of 2.30K. In addition, there is no air convection. When comparing only the heat radiation state, the R134a refrigerant in the front, middle and rear sections will have a large temperature drop when considering the heat radiation, and the closer to the outer casing side The larger the temperature difference, the biggest difference is in the inner wall of the inner tube of the rear section, and the temperature difference is 5.05K. Therefore, it can be determined that the heat radiation still has an influence on the change of the temperature value of the heat exchanger outlet.
Keywords：R134a refrigerant, heat radiation effect, heat transfer efficiency, double tube heat exchanger.
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