静态闪蒸过程汽泡生长的理论与实验研究

Experimental and Analytical Studies of Bubble Growth in Water during Static Flash Evaporation

中文关键词: 静态闪蒸  汽泡生长  实验研究  理论模型

英文关键词: Static flash evaporation  Bubble growth  Experimental study  Analytical model

中文摘要:

      本文针对去离子水静态闪蒸时单汽泡的动态生长过程开展了可视化实验观察及理论分析，研究了过热度和闪蒸腔压力对汽泡生长的影响。理论模型考虑了汽泡成核点附近固体壁面对汽泡生长的影响，通过与实验结果的对比表明，壁面效应对汽泡生长影响显著，尤其是汽泡生长速率较小时，引入壁面效应后的理论模型能更好的与实验结果相吻合。通过分析汽泡生长过程的动力学特征可知，相同闪蒸腔压力但过热度较大时，汽泡生长过程具有较短的表面张力控制阶段，并在过渡阶段和传热控制阶段均具有较大的生长速率；而相同过热度但较小闪蒸腔压力时，汽泡在早期的惯性控制阶段生长速率较小，但在后期的传热控制阶段生长速率较大。

英文摘要:

      In this work, the bubble growth in water during the static flash evaporation is studied both experimentally and analytically, and the effects of superheated degree and flash chamber pressure on bubble growth are discussed. Especially, the influence of the surface near the nucleation location on bubble growth is considered in the proposed analytical model. It is shown that the analytical results are in better agreements with the experimental data when introducing the friction and surface tension effects from the solid surface near bubble, and the effect of these forces are more significant at a lower bubble growth rate. By analyzing the bubble growth dynamic characteristics, the results also show that the bubble has a shorter surface tension controlled stage and has higher growth rates in both transition and heat-transfer controlled stages at a higher superheated degree with same flash chamber pressure. On the other hand, at the operating condition of a lower flash chamber pressure while constant superheated degree, the bubble has a lower growth rate at the inertial controlled stage, but has a higher growth rate at the heat-transfer controlled stage.