| 池沸腾孤立气泡生长过程中微液层蒸发影响的实验和模拟耦合分析 |
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| 引用本文： | 潘丰,王超杰,母立众,贺缨.池沸腾孤立气泡生长过程中微液层蒸发影响的实验和模拟耦合分析[J].化工学报,2021,72(5):2514-2527. |
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| 作者姓名： | 潘丰 王超杰 母立众 贺缨 |
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| 作者单位： | 大连理工大学能源与动力学院，辽宁 大连 116024 |
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| 基金项目： | 国家科技支撑计划项目(2013GB113005B);国家自然科学基金项目(51976026) |
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| 摘 要： | 微液层蒸发是沸腾过程中重要的换热机理。本文旨在通过单个气泡池沸腾实验中测得的气泡动态参数探究孤立气泡生长过程中加热表面的换热机理。首先通过沸腾池和加热表面的严格设计实现了单个气泡沸腾。进一步通过对孤立气泡生长时序图像的处理，得到了气泡在一个生长周期内气泡直径、纵横比以及气泡根部基圆半径的变化。对比发现，气泡生长速率与气泡根部基圆半径随时间的变化呈现显著正相关，而与大液层区域的变化相关程度较低，这表明微液层蒸发直接影响气泡体积变化，在孤立气泡沸腾过程中起主导作用。在此基础上进一步建立了加热表面换热过程的数值模型，基于实验中测得的气泡动态参数对气泡底层的微液层厚度进行了预测；通过多次迭代计算并匹配气泡生长速率和加热棒的温度发现，当表面过热度为4.82 K时，气泡底层微液层厚度约为3.43 μm，与相关文献中的微液层厚度测量值基本一致，进一步证实了微液层蒸发在孤立气泡沸腾换热过程中的重要性。本研究揭示了孤立气泡池沸腾过程中近壁面处的换热机制，为进一步的孤立气泡沸腾传热过程数值模拟奠定了理论基础。
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| 关 键 词： | 相变 蒸发 气泡 气泡生长速率 基圆半径变化 微液层厚度预测 |
| 收稿时间： | 2020-10-09 |
Analysis of the influence of microlayer evaporation on single-bubble pool boiling by coupling the experimental observations and numerical simulations |
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| PAN Feng,WANG Chaojie,MU Lizhong,HE Ying.Analysis of the influence of microlayer evaporation on single-bubble pool boiling by coupling the experimental observations and numerical simulations[J].Journal of Chemical Industry and Engineering(China),2021,72(5):2514-2527. |
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| Authors: | PAN Feng WANG Chaojie MU Lizhong HE Ying |
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| Affiliation: | School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, Liaoning, China |
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| Abstract: | The evaporation of the micro-liquid layer is an important heat exchange mechanism in the boiling process. This paper aims to investigate the heat transfer mechanism in boiling surface with an isolated bubble via the bubble dynamics observed in the boiling experiment. The single-bubble pool boiling was realized and the sequential images of the growth of the single bubble under different input heat fluxes were obtained first. The bubble sizes and radii of the root adhesive to the heating surface during the bubble period were further measured. Through the comparison between the measured bubble growth rate and the variation of bubble root radius, it is found that, the bubble growth rate is remarkably correlated with the variation of bubble root radius, whereas its correlation with the evolution of the macro-liquid layer region is relatively lower. This indicates that it is the evaporation of the micro-liquid layer underneath the growing bubble, rather than the macro-liquid layer at the vicinity of the bubble that plays a dominant role in the phase change process of single-bubble boiling. A numerical model of boiling heat transfer was established by matching the observed variation of bubble growth rates and measured temperatures of discrete points on the basis of micro-liquid layer evaporation. The heated surface was divided into three parts with different heat transfer mechanisms: dry area, micro-liquid layer region and natural convection region. Through multiple iterative computations for matching the measured data of bubble growth and the temperature underneath the heating surface, the micro-liquid layer thickness can be predicted as 3.43 μm when the surface superheat was 4.82 K. The predicted micro-liquid layer thickness is in a favorable agreement with the available references, which further confirms the dominant role of micro-liquid layer evaporation during the phase change of isolated-bubble boiling. This work provides theoretical basis for the future numerical simulation of isolated-bubble boiling heat transfer. |
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| Keywords: | phase change evaporation bubble bubble growth rate evolution of bubble root radius prediction of micro-liquid layer thickness |
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