冷凝核化过程的团簇演化机制及反射光谱特性

项目名称： 冷凝核化过程的团簇演化机制及反射光谱特性

项目编号： No.51476018

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 能源与动力工程

项目作者： 兰忠

作者单位： 大连理工大学

项目金额： 81万元

中文摘要： 探索壁面凝结系统中，蒸汽分子靠近具有特定微观结构的冷凝壁面、聚集形成团簇体、核化形成初始液滴并开始生长的微观过程机制，是研究壁面微观结构影响凝结换热过程机理的钥匙，也是完善凝结基础理论的重要组成部分。项目拟通过凝结过程壁面反射光谱的理论分析和实验研究，结合热力学分析和数值模拟，进一步定量描述蒸汽分子团聚成核的初始冷凝物理图景，并揭示壁面微观结构影响冷凝成核过程的微观机制。研究中，建立结构表面凝聚相分布特征与反射光谱特征关联模型，通过初始冷凝过程反射光谱演化实验数据对冷凝过程中的团簇及微小液滴分布特征进行分析；通过热力学模型计算和数值模拟，获得特定条件下的团簇尺寸分布理论预测值，并与反射光谱分析结果对比，从而定量描述初始冷凝阶段团簇及微小液滴的尺寸分布及演化特征；在此基础上，通过壁面反射光谱特性实验分析壁面微观结构对核化过程的影响，以及由此产生的对冷凝传热过程的影响，探索传热强化的新机制。

中文关键词： 滴状冷凝；核化；团簇；结构表面；反射光谱

英文摘要： The underlying mechanism of initial condensation stage is an intresting and important topic for the better understanding of vapor condensation heat transfer theory. In steam condensation system, the vapor molecules aggragate togther in the form of clusters, deposite onto the condensation surface, grow up to the critical size, and finally become initial nucleis. The nucleation process can be greatly affected by the surface properties, such as wettability and microstructure. The relationship between the microstructure parameter of condensation surface and the initial condensation process is very important from both academic and practical perspectives.In the present study,the clustering physical condensation model will be introduced into vapor condensation system, and the effect of surface structure to the evolution of clusters and micro droplets during the initial vapor condensation process will be investigated by the combination of thermodynamic model analysis,numerical simulation and the application of reflectance spectrum analysis.The relationship between surface properties and reflectance spectrum will be investigated first to estabilish a mathematical model to evaluate the distribution of clusters and initial droplets on the condensation surface. By the application of thermodynamic model analysis and numerical simulation, the evolution of clusters/droplets size distribution will be calculated. And the predicted therotical results will be compared with that from the reflectance spectrum experiments. Later, reflectance spectrum experiments will be conducted on various condensation surfaces with different microstructures to investigate the relationship between microstructure and nucleation process. Finally, the effect of surface microstructure on the nucleation and heat transfer process is studied in order to explore the new mechanism of heat transfer enhancement.

英文关键词： Dropwise condensation;Nucleation;Cluster;Surface microstructure;Reflectance spectrum