A Theoretical and Experimental Investigation of the Effect of Surface and Flow Conditions on Nucleate and Transition Boiling

提出了一种在垂直表面上池和强迫流动条件下完全发育的核沸腾和过渡沸腾的分析和实验研究方法。一个沸腾的三区域模型构成了理论工作的基础。对壁面区、中间区和汽流动力学主导区这三个区域分别进行分析。实验将在不同润湿性和粗糙度的表面上进行。用电子显微镜测定表面空腔的尺寸分布，并建立表面的广义Weierstrass函数。实验将在饱和水中进行。在流动沸腾实验中，孔隙率在0 ~ 20%之间变化。实验工作将与分析工作相辅相成。一旦完成，这项研究将允许对完全发展的核和过渡沸腾热流作为壁过热的函数进行近乎理论的预测。模型的输入将是表面润湿性、空腔尺寸分布函数、流体热物理性质以及几何和流动条件。这项研究将为执行一个标准问题铺平道路。它还将指导两层表面的发展，以被动增强在核沸腾的整个范围内的热流。

An Analytical and experimental study of fully developed nucleate and transition boiling under pool and forced flow conditions on a vertical surface is proposed. A three region model of boiling forms the basis of the theoretical effort. An analysis will be carried out for each of the three regions, namely, the wall region, the intermediate region, and the vapor flow dynamics dominated region. Experiments will be conducted on surfaces having different degrees of wettability and roughness. The size distribution of cavities on the surface will be determined with an electron microscope and generalized Weierstrass type of functions will be developed for the surface. The experiments will be conducted with saturated water. In the flow boiling experiments, the void fraction will be varied from 0 to 20 percent. The experimental work will be complementary to the analytical effort. When completed, the study will allow a nearly theoretical prediction of fully developed nucleate and transition boiling heat fluxes as a function of wall superheat. The input to the model will be the surface wettability, the cavity size distribution function, the fluid thermophysical properties, and geometrical and flow conditions. The study will pave the way for carrying out a standard problem. It will also guide the development of two-tiered surfaces for passive enhancement of heat fluxes over the complete range of nucleate boiling.