疏水水平管滴状冷凝研究:液滴脱落分区特征  

Dropwise Condensation on Hydrophobic Horizontal Tube:Droplet Departure Characteristics in Subregion

作　　者：刘渊博 李世成[1] 李启迅 张帅帅[1] 兰忠[1] 温荣福[1] 马学虎[1] LIU Yuanbo;LI Shicheng;LI Qixun;ZHANG Shuaishuai;LAN Zhong;WEN Rongfu;MA Xuehu(Liaoning Key Laboratory of Clean Utilization of Chemical Resources,Institute of Chemical Engineering,Dalian University of Technology,Dalian 116042,China)

机构地区：[1]辽宁省化工资源清洁利用重点实验室,大连理工大学化学工程研究所,大连116024

出　　处：《工程热物理学报》2024年第4期1169-1178,共10页Journal of Engineering Thermophysics

基　　金：国家自然科学基金重点资助项目(No.51836002)。

摘　　要：在电力系统中,滴状冷凝能够有效提升凝汽器传热性能,其中液滴动态行为与其传热过程息息相关,明确液滴动态行为对凝汽器的设计具有指导意义。本文利用PFA疏水涂层改性紫铜圆管,在空气中的接触角为142.6°能实现稳定的滴状冷凝。与竖壁冷凝中液滴脱落过程不同,水平管上液滴受到的重力分量与水平管周向角有关,造成液滴延水平管周向的脱落尺寸的差异,以此为基础将水平管表面进行分区,并提出“局部冲刷”和“完整冲刷”两种液滴冲刷模式;脱离液滴的位置和时序性差异形成下部较高的表面更新率,在液滴尺寸r<400μm的范围内,下部分的液滴数密度高于上部分;局部冲刷可限制下部分区域液滴尺寸,降低液滴覆盖面积。Dropwise condensation can improve the efficiency of condenser in power generation system and the droplet dynamic behavior is closely related to the heat transfer process.It is significant to clarify the droplet dynamic behavior for condenser design.In this work,the PFA hydrophobic coating is used to modify the copper tube,and the contact angle in the air is 142.6°,which could achieve stable dropwise condensation.Different from the droplet departure process on vertical wall,the gravity component acting on the droplet is related to the circumferential angle of the horizontal tube,then the droplet departure sizes along the circumferential direction of the horizontal tube show discrepancy.Based on this,the surface of the horizontal tube is divided into two regions,and two droplet sweeping modes‘local sweeping'and‘complete sweeping'are proposed.The differences of departure position and time sequence cause a higher surface renewal rate at the lower region,the droplet number density of the lower part is slightly higher than that of the upper part within droplet size range of r<400μm.The local sweeping can limit the droplet size in the lower region and reduce the droplet coverage area.

关 键 词：滴状冷凝 水平管 液滴脱落行为 尺寸分布 低压蒸汽 

分 类 号：TK123[动力工程及工程热物理—工程热物理]