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

表面和流动条件对核沸腾和转变沸腾影响的理论和实验研究

基本信息

批准号：
8821447
负责人：
Vijay Dhir
金额：
$ 11.94万
依托单位：
University of California-Los Angeles
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
1989
资助国家：
美国
起止时间：
1989-01-15 至 1991-09-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=8821447&HistoricalAwards=false
关键词：
Theoretical Experimental Investigation Effect Surface

项目摘要

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.

充分发展形核的分析与实验研究和过渡沸腾池和强制流动条件下，建议垂直面。沸腾的三区模型这是理论工作的基础。分析将是三个区域，即隔离墙，区域、中间区域和蒸汽流动动力学主导区域。实验将在表面上进行具有不同程度的润湿性和粗糙度。大小表面上空穴的分布将由电子显微镜和广义维尔斯特拉斯型将为表面开发功能。实验将用饱和水进行。在流动沸腾实验中，空隙率将从0变化到20 百分之实验工作将是对分析的努力。完成后，这项研究将允许一个几乎理论上的充分发展核态沸腾和过渡沸腾的预测热通量作为壁面温度函数。的输入模型将是表面润湿性，空腔大小分布函数，流体热物理性质，以及几何和流动条件。这项研究将为以下方面铺平道路：解决一个标准问题。它还将指导发展两层表面，核态沸腾整个范围内的热通量。