Enhancement of Film Condensation Using a Porous Coating: A Theoretical and Experimental Investigation

在固体不渗透表面上使用高导电性和渗透性的多孔涂层，对膜冷凝中传热的增强进行了研究。一个初步的简单的膜凝结模型将被扩展，以发展一个更复杂的模型来预测凝结速率。将报告水平和倾斜板和管的传热率。该模型将考虑汽阻、强制对流和相对渗透率的影响，在液/气界面处加入匹配条件。理论研究的主要结果将是记录薄膜厚度、速度和温度分布以及局部传热系数对多孔基质参数的依赖关系，并将这些结果与(i)努塞尔的经典分析和（ii）其他增强薄膜冷凝的先进方法（例如，积分或凹槽翅片表面）进行比较。研究的实验部分将侧重于从多孔涂层表面获取薄膜冷凝传热数据，并在广泛的实验条件下对冷凝过程进行摄影观察。传热系数的测量将通过在倾斜多孔涂层板上冷凝氟利昂-113来获得。实验结果验证了理论膜冷凝模型，该模型预测了相当大的换热系数。

An investigation of the enhancement of heat transfer in film condensation with the use of a highly conductive and permeable porous coating on a solid impermeable surface is to be made. A preliminary simple film condensation model will be expanded to develop a more complex model for predicting the condensation rate. Heat transfer rates for horizontal and inclined plates and tubes will be reported. The advanced model will incorporate matching conditions at the liquid/vapor interface which will account for the effects of vapor drag, forced convection and relative permeability. The main results of the theoretical research will be to document the dependence of the film thickness, velocity and temperature distributions, and local heat transfer coefficient on the porous matrix parameters and to compare these results to (i) the classical analysis of Nusselt and (ii) other advanced methods of enhanced film condensation (e.g., integral or fluted fin surfaces). The experimental part of the investigation will focus on the acquisition of film condensation heat transfer data from a porous coated surface and on photographic observations of the condensation process over a wide range of experimental conditions. Measurements of the heat transfer coefficient will be obtained by condensing Freon-113 on an inclined porous coated plate. Verification of the theoretical film condensation model, which predicts a considerable heat transfer coefficient, is anticipated by the experimental results.