双模态过渡池沸腾实验研究

Experimental Study on Two-mode Transitional Pool Boiling

利用控制加热电压和加热面平均温度两种方法,实验研究了常压(0.1MPa)、室温(16℃)条件下除气后的R113在直径60μm细铂丝表面的池沸腾传热现象,观测了单相对流、核态沸腾、双模态过渡沸腾和膜态沸腾4种传热模式中的汽相分布及其传热特征,发现充分发展的核态沸腾传热曲线、膜态沸腾传热曲线及临界热流的数值分别与文献中常用关联式的预测一致,而核态沸腾和膜态沸腾共存的稳定双模态过渡沸腾曲线被一极小值点分为两个连续分支,邻近膜态沸腾的右支上热流与过热度成正比,而邻近核态沸腾的左支上热流则随过热度增长而下降,并且只出现在加热面平均温度受控的实验中.

In the present paper, pool boiling heat transfer of degassed R113 on thin Platinum wires of 60μm in diameter at 0. 1MPa and 16℃ was experimentally studied using the voltage-controlled and temperature-controlled heating methods. The vapor distribution and characteristics of heat transfer in four modes, namely single phase natural convection, nucleate boiling, two-mode transitional boiling, and film boiling, were observed and measured. It＇ s found that the curves of heat transfer both in fully developed nucleate boiling and in film boiling and the value of the critical heat flux （CHF） were consistent with the predictions by the correlations commonly used in the literature. It＇ s also found that the curve of heat transfer in the steady two-mode transitional boiling, in which nucleate boiling and film pool boiling co-exist on the wire, was divided into two continuous branches by a minimum. The heat flux increases linearly with the superheat in the right branch adjoining film boiling curve, while it decreased with the superheat in the left branch close to nucleate boiling curve. The left branch could be observed only in the temperature-controlled experiment.