中文摘要：

为研究加热面周围边界条件对气泡微细化沸腾的影响，结合实验与数值模拟对加热面低于水箱底面0．5 mm以及与之齐平两种条件下加热面上气泡行为和气泡周围流场进行对比分析。实验结果表明，50 K过冷度下，加热面齐平时，会发生旺盛的MEB现象，而对于加热面下沉时，微细化沸腾现象不发生。数值分析表明，加热面下沉时，气泡周围Marangoni对流被减弱，且气泡顶部的冷凝被大幅削减。这使得气泡稳定地在加热面上形成并逐渐长大，无法形成微细化沸腾现象。因此，气膜周围的Marangoni对流和气液界面上的冷凝过程可能是导致微细化沸腾发生的主要原因。

英文摘要：

This study conducts experiments for two cases to demonstrate the effects of the boundary condition around the heating surface on microbubble emission boiling. For one case, the heating surface flushes with the tank bottom and for the other one, the heating surface is about 0.5 mm lower than the tank bottom. Comparison is made for the bubbling performance and flowing velocity under the above two conditions. Experimental results showed that micro-bubble emission boiling （ MEM） occurred vigorously with 50 K subcooling in the first case, while in the second case, the MEB phenomenon did not occur. The data analysis shows that Marangoni convection near the bubble is weakened and the condensation at the vapor-liquid interface is reduced remarkably. Both of these effects cause the bubbles to form and grow up stably on the heating surface without MEB occurring. Therefore, the conclusion is made that Marangoni convection and the condensation at the interface are possibly the reason for microbubble emis-sion boiling.