下沉加热面上气泡微细化沸腾实验研究

为分析加热面相对位置对气泡微细化沸腾（MEB）的影响，对下沉加热面上的过冷沸腾进行了实验研究，并与齐平加热面实验结果进行了对比。25～50 K过冷度范围内，在下沉3 mm加热面上观察到了MEB现象。在50 K过冷度下，MEB时的热流密度可达5.55 MW/m²。可视化结果表明：在MEB区域，下沉加热面上形成的蒸汽气膜会频繁地膨胀收缩；随过冷度的升高，膨胀收缩的周期增加，而幅值变化较小。此外，相比于齐平加热面条件，下沉加热面周围的壁面可显著限制蒸汽气膜的横向膨胀。

Experimental Investigation on Microbubble Emission Boiling on Imbedded Heating Surface

In order to analyze the effect of relative location of heating surface on microbubble emission boiling (MEB), the subcooled boiling occurred on an imbedded heating surface was experimentally studied, and compared with that on a flush heating surface. At liquid subcooling of 25-50 K, MEB was observed on an imbedded heating surface that lowers tank bottom for 3 mm. The heat flux in MEB reaches 5.55 MW/m² at liquid subcooling of 50 K. Visualized results indicate that a vapor film forms on the heating surface, and expands and shrinks frequently in regime of MEB occurred on the imbedded heating surface. The increase of liquid subcooling enlarges the period of expansion and shrinkage of the film while has limited effect on its amplitude. Furthermore, the lateral expansion of vapor film in MEB can be limited by the surrounding edge of the imbedded heating surface significantly.