充满多孔质材料竖直套管内的自然对流沸腾换热

Natural Convective Boiling in Vertical AnnularTubes Filled with Porous Medium

以饱和水和饱和Ｒ１１为工质，对竖直同心套管内填充玻璃珠多孔介质层时自然对流沸腾的换热特性进行了实验研究．结果表明，在竖直套管内填充固体颗粒可以强化沸腾换热，在低热负荷区的强化效果尤为明显．多孔层对Ｒ１１沸腾特性的影响要比对水的影响小得多．文中利用均相流模型对填充多孔质流路内的自然对流沸腾临界热通量进行了研究，得到了无量纲理论表达式，通过实验发现，实验点区域在最大值和最小值理论曲线范围内，其趋势和理论预示基本吻合．

Experimental studies are made for the natural convective boiling on uniformly heated vertical annular tubes submerged in saturated water and saturated R11. The experimental results are compared with the case without porous medium. The results show that with the porous media, the heat transfer coefficients are enhanced especially in the low heat flux zone. The influences of porous medium on boiling properties of water are much bigger than that of R11. A theoretical study is also made for the critical heat flux. By adopting a kind of homogeneous flow model, a generalized formula is set up which agrees well with the experimental data.