不同宽度窄缝通道过冷沸腾

Subcooled boiling in narrow channels with different sizes

以去离子水为实验工质,在窄缝宽度δ=3、4mm,质量流速G=143、300kg·m^(-2)·s^(-1),主流过冷度ΔTsub=17、25℃,热通量q=1~20 W·cm^(-2)的参数范围内,对常压下竖直窄缝通道内向上流动过冷沸腾的换热规律进行了实验研究。对不同宽度窄缝通道内的同一区域过冷沸腾气泡演变过程进行了可视化实验分析,发现窄缝宽度因素对过冷流动沸腾的流动换热特性和壁面核化特性影响显著,其中包括沸腾起始点ONB,压降ΔP,传热系数h,汽化核心密度Na,气泡脱离直径Dd,气泡脱离频率f等。

In present paper,the heat transfer characteristics of subcooled flow boiling in vertical rectangular narrow channels of different size at atmospheric pressure were investigated experimentally by using deionized water as working fluid,under the working conditions that widthδfrom 3mm to 4 mm,mass flux G=143 &300kg·m^(-2)·s^(-1),inlet subcoolingΔTsub=17 &25℃,heat flux qfrom 1 W·cm^(-2)to 20 W·cm^(-2).The visualization experiments were conducted to study the characteristics of bubble nucleation on the heating wall in the same area,then obvious channel size effects were found out,including effects on onset of boiling,heat transfer coefficient,active nucleation site density,bubble departure diameter and bubble departure frequency,etc.