实现水蒸汽滴状冷凝的表面材料研究

New surface materials for dropwise condensation heat transfer of steam

分别采用离子注入、等离子体聚合和动态离子束混合注入技术在黄铜管外表面制备了具有低表面能的非晶态离子注氮合金、聚六氟丙烯和聚四氟乙烯表面，实现了水蒸汽在常压下的滴状冷凝。实验结果表明，各种表面均能提高冷凝传热系数约２０倍，由于不同技术制备的表面形成滴状冷凝的机制不同，各具有不同的特性。分析讨论了各种技术制备低表面能表面的特点及其应用前景。

Ion implantation,plasma polymerization and dynamic ion-beam mixed implantationmethods have been presented by preparing nitrogen-implanted amorphous state alloy layer,polyhexaflouropropene film and polytetraflouroethylene film , respectively. These films are coatedon the external surface of brass tubes with the diameter of 16/14 mm and the length of 400 mm.Steady dropwise condensation of steam under the atmosphere pressure is observed. Theexperimental results indicate that the condensation heat transfer coefficients of all the surfaces canbe increased by about 20 times compared with that of filmwise condensation. However,the periodfo time maintaining dropwise condensation is dependent on the mechanisms of promotingdropwise condensation and the processing conditions of the surfaces made by various metheds.The characteristics and the prospects of the surfaces are discussed finally.