BOILING HEAT TRANSFER ON SURFACES WITH ARTIFICIAL NUCLEATION SITES (Ⅰ) EFFECT OF CAVITY SIZE, CAVITY DENSITY ON BUBBLE DEPARTURE DIAMETER AND FREQUENCY

By means of high-speed photography and optical-fiber probe, the effect of nucleation cavity size and cavity density on the bubble departure diameter and frequency has been investigated. The enhanced heating surface employed has artificial nucleation sites arranged regularly.Based on the analysis of the various forces exerted on the vapor bubble, a mathmatical model has been developed for correlating bubble departure diameter and frequency with the surface geometry and the degree of superheat.Experimental data has confirmed the availability of the model presented.     

人工汽化中心表面核状沸腾传热的研究——(Ⅱ)关于核状沸腾传热机理以及汽化中心的大小和密度对沸腾给热系数的影响

本文在前人提出的各种沸腾传热机理模型的基础上,建立了一个关于核状沸腾传热机理的综合模型,并在规则排列的、不同汽化中心密度和孔径的人工汽化中心表面上进行了沸腾传热实验,对所提出的模型进行了验证.模型计算结果与实验结果符合良好,文中根据所建立的模型分析了汽化中心的大小和密度对沸腾传热速率的影响.     

BOILNG HEAT TRANSFER ON SURFACES WITH ARTIFICIAL NUCLEATION SITES (Ⅱ) MECHANISM OF NUCLEATE BOILING AND EFFECT OF CAVITY SIZE, CAVITY DENSITY ON BOILING HEAT TRANSFER

A new comprehensive physical model for nucleate boiling heat transfer on surfaces with artificial nucleation sites has been proposed. Good agreement with experimental results has shown the applicability of the model.     

ENHANCEMENT OF NUCLEATE BOILING HEAT TRANSFER WITH ADDITIVES

Based on the tests of more than ten different additives, several effective additives are found capable of improving the boiling heat transfer behavior of water pronouncedly. The mechanism of the enhancement of nucleate boiling with additives has been investigated, and the results indicate that one of the important reasons is that the nucleation sites have been increased.     

人工汽化中心表面核状沸腾传热的研究——(Ⅰ)汽化中心的大小和密度对沸腾过程中汽泡脱离直径和频率的影响

本文用高速摄影和光导纤维探头两种方法;在规则排列的人工汽化中心表面上,考察了汽化中心的大小和密度对汽泡脱离直径和频率的影响.基于汽泡受力分析,考虑到由于汽化中心密度的增加对汽泡脱离的影响,本文建立了描述汽泡脱离直径和频率与汽化中心大小、密度以及壁面过热度之间关系的数学模型.并通过系统的实验数据加以验证.