气泡微细化沸腾传热特性  

Heat transfer property of micro-bubble emission boiling

作　　者：朱光昱 高力 于方小稚 田齐伟 

机构地区：[1]中国核电工程有限公司总体所,北京100084 [2]北京理工大学自动化学院,北京100081

出　　处：《核技术》2015年第12期77-80,共4页Nuclear Techniques

基　　金：国家自然科学基金(No.51376052)资助~~

摘　　要：气泡微细化沸腾(Micro-bubble Emission Boiling,MEB)是一种特殊的过冷沸腾现象,当其发生时加热面的热流密度会远高于临界热流密度(Critical Heat Flux,CHF)。根据采集到的可视化沸腾资料,对MEB的传热机理进行了分析。结果表明,MEB发生时,加热面上不稳定气膜的周期性破裂,破坏了过热液层,导致了良好的气液置换对流换热。考虑MEB的特殊传热过程,对Rohsenow关系式中部分项进行修正,并根据最小二乘法对实验数据进行拟合,得到了适用于10 mm铜加热面上的MEB沸腾关系式,误差不超过±15%,可满足一般的工程计算要求。Background： Micro-bubble Emission Boiling （MEB） is a special subcooling boiling phenomenon that the heat flux increases more highly than critical heat flux （CHF）. Due to its extremely high heat transfer capability, many researchers have shown interest in it. Purpose： In this paper, we fit the heat transfer correlation of experimental data collected in visualized boiling experiments after deeply analyzing the heat transfer mechanism of MEB. Methods： Four Si-C heaters were employed for heating the copper block, which has a round heating surface with diameter of 10 mm on its upper. Temperature data were measured by T-type sheathed thermocouples. The temperature of the heating surface was obtained by extrapolating the temperature distribution. Based on the heating surface temperature date in different subcoolings, least square method was used to fit Rohsenow relation to MEB. Bubble behaviors were captured by high-speed video camera with light system. Results： The experimental results showed that, when the subcooling exceeded 40 K, disturbance emerged at the liquid-vapor interface and the micro-bubble emission boiling occurred after the CHF was attained, thereafter the heat flux increased rapidly with the superheat increasing like that in typical nucleate boiling region. Based on Rohsenow relation, MEB heat transfer correlation is fitted according to the measured temperature data for heating surface of 10-mm copper in different subcoolings. The error of the relation is less than ＋15%, which meets the requirement of general engineering. Conclusion： The efficient convective heat transfer of vapor-liquid replacement caused by periodic damage of the unsteady vapor film on the heating surface is the heat transfer mechanism of MEB.

关 键 词：气泡微细化沸腾 临界热流密度 最小二乘法 

分 类 号：TL334[核科学技术—核技术及应用]