摘 要：由于制冷剂R11和R123对臭氧层有破坏作用，为完成环保新工质R245fa对R11和R123的替代工作，对R245fa在内螺纹外斜翅片的三维双侧强化管外的凝结换热性能进行试验。数据处理过程中，采用Wilson图解法获得管内水侧对流换热系数及其计算关联式，再利用热阻分离法获得管外凝结换热系数。研究表明：试验中管内对流换热系数高于管外冷凝换热系数，所以管外侧的传热热阻是占据主导地位的传热热阻；相对于光管，R245fa在三维双侧强化管管内换热强化换热倍率为3.58，管外强化换热倍率为2.48；对实验数据进行拟合，得到管外换热系数的变化规律和凝结换热关联式。

Abstract:Due to the destruction role played by the refrigerant R11 and R123 to the ozone layer and to fulfil the substitution of R11 and R123 with new environment friendly working medium R245fa,the condensing heat exchange performance of R245fa outside a threedimensional internallythreaded obliquely finned dualside intensified heat exchange tube was tested.During the data processing,the Wilson graphic method was adopted to obtain the convective heat exchange coefficient at the inside of the tube and its calculation correlation formula and then the heat resistance separation method was employed to acquire the condensing heat exchange coefficient outside the tube.It has been found that during the experiment,the convection heat exchange coefficient inside the tube is greater than the condensing one outside the tube,therefore,the heat transfer thermal resistance outside the tube will dominate.Relative to a bare tube,R245fa will have an intensified heat exchange ratio of 3.58 inside the three-dimensional dual-side intensified heat exchange tube and an intensified heat exchange ratio of 2.48 outside the tube.After a fitting of the test data have been performed,the law governing the heat exchange coefficient outside the tube and the condensing heat exchange correlation formula were obtained.

TB657.5