考虑传质、蒸汽速度以及分界面剪切力影响的竖直管内流动凝结换热特性

Condensation Characteristics Inside a Vertical Tube Considering the Presence of Transfer Vapour Veloctty and Interfacial Shear

膜状凝结由成型膜状凝结和成熟膜状凝结两部分组成。目前分析只考虑了由传质和蒸汽速度引起的动量传递对凝结产生的影响。本文提出两个表征凝结换热的系数即相对速率B和动量传递系数U ,以及综合传质、蒸汽流速和热物性的系数ω来描述凝结换热的机制。研究表明 ,分界面剪切力和传质的影响很大程度上是依赖于工作介质的热物性和实验温度 。

Condensation processes are divided into two sec tions:the forming film section and the formed film section.The present analysis takes into account the effects of momentum transfer that results from mass transfer and vapor flow on the interfacial shear and hence condensation.Two major parameters that govern the condensation heat transfer the relative velocity ratio B and the momentum transfer factor U along with a comprehensive factor ω that includes mass transfer,the vapor velocity and the thermophysical properties ,are proposed to describe the condensation mechanism.It is shown that the effects of the interfacial shear and mass transfer are strongly depended on the thermophysical properties of the working fluids and the operating temperatures.At last analysis the practical situation entirely applied to the model by experiments to testify the feasibility of it.