薄层多孔层内池沸腾液体回流机理分析

Mechanism Analysis of Pool-boiling Liquid Backflow in Thin Porous Coatings

为探讨薄层多孔层内池沸腾时的液体回流机理,通过光滑平板和不同薄层多孔介质的池沸腾实验,获得了多孔介质表面气泡沸腾特性和池沸腾曲线,结合实验结果计算了薄层多孔介质层内液体的最大回液流速、毛细极限,并分析了多孔介质层内液体回流机理及毛细极限的形成机理。研究结果表明:多孔介质存在弯液膜,回液流速高,不易出现局部干涸;多孔介质毛细压力和渗透率越大,回液效果越好;单核化点回液不足后,核化密度增大,回液仍不足后出现局部干涸,即出现毛细极限。

To study the pool-boiling liquid backflow mechanism in thin porous coatings, pool-boiling experiments of smooth surface and different porous coatings were conducted to obtain corresponding bubble boiling characteristics and pool boiling curves. Combined with experimental results, maximum liquid backflow speed and capillary limit in the thin porous coatings were calculated, while the formation mechanism of both the liquid backflow and capillary limit analyzed. Results show that there exists curved liquid membrane in porous coatings, and local dry is hard to appear due to higher liquid backflow speeds; the higher the capillary pressure and permeability of porous medium, the better the liquid backflow effect; lack of liquid backflow in single point will lead to more nucleation points, and if the liquid backflow is still inadequate, local dry will occur, that is capillary limit.