结霜工况下水蒸气在冷表面上冷凝成核的理论与实验研究  

Theory and experimental study of water vapour nucleation process on a cold surface in frosting condition

作　　者：洪天顺 梁彩华[1] 吕宁[1] HONG Tianshun;LIANG Caihua;LÜNing(School of Energy and Environment,Southeast University,Nanjing 210096,China)

机构地区：[1]东南大学能源与环境学院,江苏南京210096

出　　处：《中南大学学报（自然科学版）》2021年第6期1865-1875,共11页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(51676033);“十三五”国家重点研发计划项目(2016YFC700304)。

摘　　要：为了揭示结霜初期冷表面上冷凝成核过程的发展规律及其影响因素,针对结霜工况下冷表面在凝结初期的冷凝成核过程,建立基于吉布斯自由能理论与分子动力学理论的理论模型,并对结霜工况下低温铝表面的凝结过程进行可视化实验研究。研究结果表明:通过理论模型所得成核能障系数变化特征与实验结果有良好的一致性;成核位点的凝结成核能障系数越低,越容易形成初始液核;在凝结开始后50 s内,初始液核的位点的成核能障系数随时间呈线性递增;在冷凝成核阶段,由于水蒸气在凹结构上形成液核的成核能障较小,初始液滴会优先出现在表面上存在划痕、凹槽的区域;水蒸气冷凝形成初始液核的困难程度随着基底材料表面能降低而增加,随着冷表面温度升高而增加,随着空气露点温度降低而增加。In order to study the condensation nucleation process on a cold surface at the initial stage of frosting,a theoretical model based on Gibbs free energy and molecular dynamics theory was established.A visual experiment of condensation on cold aluminum surface in frosting conditions was carried out.The results show that the variation characteristies of the nucleation energy barrier coefficient obtained by the theoretical model are in good agreement with those of the experiment.The priority of forming the initial liquid nucleus for a nucleation site decreases with the increase of the nucleation barrier coefficient.Within 50 s after the start of condensation,the nucleation barrier coefficient of the nucleation site where the initial liquid nucleus appears increases linearly with the increase of time.The difficulty of water vapor nucelate to form the initial liquid core increases with the decrease of the surface energy of the substrate material,increases with the increase of the cold surface temperature,and increases with the decrease of the air dew point temperature.

关 键 词：结霜 凝结成核 成核能障 

分 类 号：TK124[动力工程及工程热物理—工程热物理]