Investigation on Characteristics of Temperature and Velocity Distribution Near Wall on Subcooled Boiling
The temperature distribution of near-wall liquid in nuclear boiling and microbubble emission boiling(MEB)with liquid subcooling covering 25～40 K are experimentally investigated.The results show that in the nuclear boiling region,the liquid heat near the heating surface is carried away by bubble growth,detachment and buoyance,with the high temperature zone near the wall is mainly concentrated above the heating surface.In MEB region,no bubble detachment occurs,and the liquid heat near the wall is transferred to the bulk through the convective process induced by the vigorous oscillations of the vapor film to maintain the local subcooling.The average liquid temperature above and on the edge of the heating surface is about 4 K higher than that of the bulk liquid,with intense fluctuations over time.The above results indicate that there are significant differences in heat transfer processes near the wall between nucleate boiling and MEB.
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