水平窄空间沸腾换热的数理模型研究

窄空间只有在间距小于汽泡脱离直径时，对沸腾传热强化才有比较显的效果。窄空间沸腾强化传热的机理在于较大的泡底微层加速了蒸发传热和窄空间中被加热的液体周期性地与池液进行容积交换。水平圆盘窄空间中的汽泡生长分为性质完全不同的自由生长期和抑制长大期；在一个周期内，加热面的总传热量等于壁面传导给窄空间液体的热量与通过合体泡底微层蒸发潜热之和。在对圆形水平窄空间的沸腾传热的现象和机理进行分析的基础上，提出了窄空间的沸腾换热过程的数理模型；进而对窄空间沸腾的本质规律在理论上进行了初步探索，并得到分析解。理论计算结果与实验数据比较表明，该分析解适合于中低壁面过热度的情形。由于问题的复杂性，该模型仍需不断完善。

Mathematical model of boiling heat transfer in narrow space between two horizontal discs

The effects of boiling heat transfer enhancement can be distinct only when the spacing of narrow space is smaller than the departure-diameter of bubbles. The mechanism for the boiling heat transfer of narrow space is that the relatively large micro-layer at the bottom of bubbles accelerates the evaporating heat transfer and the heated liquid in the narrow space regularly exchanges volume with the pool liquid. Based on the analysis of the phenomenon and mechanism of boiling heat transfer in horizontal annular narrow space, a mathematical model of boiling heat transfer in narrow space was proposed in this paper in an attempt to obtain a preliminary essential laws of narrow space boiling in the aspect of theoretical quantitative research and to get an analytic solution. The theoretical calculation and experimental data indicate that the analytic solution applies to the medium or low wall superheat. As the problems discussed are rather complicated, the model developed in this paper needs to be improved further.