多孔表面开槽影响池沸腾传热的实验研究

BOILING HEAT TRANSFER ON POROUS COATED SURFACES WITH VAPOR CHANNELS

本文报道了开槽密度对R11在烧结多孔表面池沸腾换热性能影响的实验研究。观察发现,多孔表面开槽,让蒸汽从槽道逸出、液体从多孔区吸入到受热面,将增强池沸腾换热。沸腾特征可分为液体灌注、槽道起泡、底部蒸干三个区。对特定的多孔层,合理开槽可获得较好的换热效果。带槽道的多孔表面实验件与均匀多孔表面相比,在相同壁面过热度条件下,热流密度提高2～10倍,临界热流密度提高2～4倍。

Boiling heat transfer on porous coated surfaces with vapor channels was investigated experimentally to determine the effects of the size and density of the vapor channels on the boiling heat transfer. Three regimes were identified: liquid flooding, bubbles in the channel, and dry-out. The heat transfers coefficient and of the porous surfaces with vapor channels was much higher than that on the smooth surface. The maximum heat transfer occurred for an optimum vapor channels density and the boiling heat transfer performance was improved if the channels were open. According to observations, vapor could escape through vapor channel while liquid sucked by porous structure, and hence, the two-phase region will extend to pool liquid at a given flux. This indicates that capillarity plays great effect in the boiling and the heat transfer performance can be increased significantly.