R417A在内螺纹管内沸腾换热的性能研究.docVIP

R417A在内螺纹管内沸腾换热的性能研究 薛睿洁 姬长发 张小艳 王跃勇 西安科技大学，陕西 710054 摘 要 三元非共沸制冷剂R417A是当前R22的替代品之一，在流动和换热性能上与R22还存在一定的差异，在文献[4] 对R417A在水平光滑管和内螺纹管中流动沸腾换热实验研究的基础上，应用Fluent软件对R417A在水平光滑管和内螺纹管中流动沸腾换热进行数值模拟研究，研究结果表明：蒸发温度对换热系数的影响不是很明显，随着干度的增加，换热系数先是增大到最大值，随后出现管壁干燥、换热系数迅速降低的换热恶化现象。换热的强化不单是微肋造成的面积增大所引起，螺纹结构所引起的湿润面积的增大、沸腾点和汽化核心的增多、扰动作用及紊流效应的增强也强化了换热，与水平光滑管相比，内螺纹管具有比较明显的强化换热效果，同时，螺纹管形成的二次流、摩擦等也造成了压降增大。 关键词 制冷剂 R417A 沸腾换热 数值模拟 PERFORMANCE STUDY OF BOILING HEAT TRANSFER OF R417A FLOWING INSIDE INTERNALLY GROOVED TUBE Xue Ruijie Ji Changfa Zhang Xiaoyan Wang Yueyong Xi’an University Of Science And Technology, Shanxi 710054 Abstract R417A, a ternary non-azeotropic refrigerant mixture, is one of current substitute refrigerant for R22，it still has some differences on flowing and heat transfer performance with R22. Based on the literature 4, the experimental study of boiling heat transfer was carried out for R417A flowing inside a horizontal smooth and internally grooved tubes, using Fluent software to simulate, the comparison of the calculation and the experimental results reveals that the influence of evaporation temperature for heat transfer coefficient is not obvious, with the increase of dryness, heat transfer coefficient increases to the maximum, than subsequent some hear transfer deterioration phenomenon like wall dry, heat transfer coefficient rapidly reduce. Strengthening heat transfer are not only caused by micro-fin, but the thread structure can increase wetting area increases, increased of boiling point and evaporation core, enhancement of disturbance effect and turbulence effect. Compared with horizontal smooth tube, internally grooved tube has obvious strengthening heat transfer effect. While the increased pressure drop is mainly due to the secondary flow, friction increases and so on. Keywords Refrigerant R417A Boiling heat transfer Numerical modeling 0 前言 近年来，随着国内制冷系统所占能耗比例越来越大，夏季用电高峰期甚至采取了拉闸限电措施，电力供应压力必将越来越大[1]，人们对高效、节能、环保的要求也愈来愈高，于是出现了许多二元和三元非共沸混合制冷剂。但是，鉴于非共沸混