水平圆管临界热流密度实验研究

Experimental Investigation on Critical Heat Flux in Horizontal Tube

对水平圆管内低质量流速临界热流密度(CHF)进行了实验研究和分析。实验研究发现,水平流动圆管沸腾临界发生在圆管加热壁面顶部。通过对沸腾临界发生时圆管出口的质量含汽率和流型进行分析发现,本文研究的参数范围内沸腾临界时的出口含汽率高,流型为环状流,沸腾临界类型为干涸型(Dryout)。将经验公式预测值与实验结果进行比较发现,Bowring公式和Lookup table的预测值远大于CHF的实验值。导致此现象出现的主要原因为:Bowring公式和Lookup table是基于竖直流动CHF实验数据开发的模型,水平流动时在重力的作用下环状流液膜呈非均匀分布,顶部液膜干涸提前触发沸腾临界造成CHF值降低。

The critical heat flux （CHF） in the horizontal tube under low flow condition is investigated in this paper. It is found that the boiling crises occur at the top of the tube. According to the exit quality and flow pattern, the category of boiling crisis in the horizontal tube low flow is considered to be dryout. The prediction results of Bowring correlation and Lookup table are much larger than the experimental data, because the Bowring correlation and Lookup table are proposed for the vertical round tube CHF prediction. The distribution of liquid film in the horizontal annular flow is asymmetrical due to gravity. It causes the dryout of liquid film at the top of tube early and the decreasing of CHF.