【摘要】 对离子束动态混合注入(DIMI)技术制备的黄铜、紫铜、不锈钢和碳钢管基聚四氟乙烯(PTFE)表面的冷凝传热实验发现,用不同加工条件制备的表面具有不同的化学组成、不均匀的表面状态以及不同的物理化学性质,从而导致不同的冷凝成滴面积和传热性能,而且表面加工条件对滴状冷凝传热的寿命有至关重要的作用,不同基体材料应有不同的最佳制备工艺条件.不同工艺条件下制备黄铜基PTFE表面水蒸气竖直管外冷凝传热通量比相应的膜状冷凝提高0.3-4.6倍,冷凝传热系数提高1.6-28.6倍.实验结果也表明冷凝表面基体材料对冷凝传热性能有一定的影响.更多还原

【Abstract】 The objective of this paper is to investigate the influence of the surface properties of polymer film on dropwise condensation heat transfer of steam, in order to prepare a viable polymer film sustaining long- term dropwise condensation. The PTFE films are coated on the external surfaces of brass tubes, copper tube, stainless steel tube and carbon steel tube by using the dynamic ion- beam mixed implantation technique, under a variety of surface processing conditions. It is found that the surface properties are greatly dependent on the surface processing conditions, and hence leading to different condensation modes and heat transfer characteristics. The experimental results indicate that condensation heat flux and heat transfer coefficient are increased by 0.4-1.5 times and 1.6-28.6 times of film condensation values, respectively, for the brass tubes treated under different conditions. Meanwhile, the surface processing condition is also crucial to the adhesion between polymer film and metal substrate. The fact that different substrate materials require different optimal processing conditions and demonstrate different condensation heat transfer coefficient, can be drawn from the present results.更多还原