大量不凝性气体存在时微纳尺度结构中液滴吸附成核及疏导的机理研究

The condensation heat and mass transfer in the presence of a large amount of noncondensable gas exists widely in various fields such as energy utilization, water desalination, chemical engineering, and energy and water conservation. This project focuses on the complex process of vapor adsorption and nucleation and droplet drainage on the surface with micro and nanoscale structures in the presence of a large amount of noncondensable gas. With the numerical simulation, theoretical analysis and experimental test, we develop the high efficient numerical methods including both the molecular dynamics simulation and the lattice Boltzmann method, and establish the accurate theoretical models of vapor adsorption and condensation heat transfer in the presence of a large amount of noncondensable gas. In addition, the records of dynamic characteristics of droplets in the presence of a large amount of noncondensable gas, the fabrication of functional surface with micro and nanoscale structures, and the comprehensive tests of condensation on the functional surface are conducted. We clarify the mechanism of efficient droplet absorption and nucleation in the micro and nanoscale porous structure under a large amount of noncondensable gas, reveal the action of micro and nanoscale structures on the noncondensable gas thermal resistance layer under multi-physics, and establish the criteria of controlling the condensation droplet distribution and movement by using the micro and nanoscale structures together with the surface wettability. The research results can provide theoretical basis for designing efficient and stable surfaces with micro and nanoscale structures. The achievements in this project are of great significance for the industries such as energy recovery and utilization, and equipment security, which involve the process of condensation heat and mass transfer.

大量不凝性气体存在时蒸气冷凝热质传递过程在能源利用、海水淡化、化工及节能节水等领域中广泛存在。本项目针对大量不凝性气体存在时蒸气在微纳尺度结构中吸附成核及液滴疏导复杂过程，通过数值模拟、理论分析与实验测试相结合，发展高效的分子动力学与格子Boltzmann数值方法，建立准确的蒸气吸附与冷凝传热理论模型，开展大量不凝性气体存在时液滴动力学特性观测、功能型微纳尺度结构制备及蒸气在微纳尺度结构表面冷凝相变的综合性能测试等实验研究，阐明大量不凝性气体存在时蒸气在微纳尺度多孔结构中的高效吸附与核化原理，揭示多物理场条件下微纳尺度结构对不凝性气体热阻层的作用机制、建立耦合微纳尺度结构和表面润湿性对冷凝液滴分布及运动特性调控的设计准则。研究结果为设计高效稳定的微纳尺度结构表面提供理论依据，对涉及大量不凝性气体存在时蒸气冷凝热质传递过程的能源回收利用及设备安全等领域具有重要意义。

大量不凝性气体存在时蒸气冷凝热质传递过程在能源利用、海水淡化、化工及节能节水等领域中广泛存在。本项目针对大量不凝性气体存在时蒸气在微纳尺度结构中吸附成核及液滴疏导复杂过程，1)在冷凝成核及吸附方面，开展了纳米粗糙表面液滴成核及生长的分子动力学模拟研究，考虑界面效应揭示了蒸气冷凝成核机理。2)在冷凝液滴快速疏导方面，建立了三相流体流动的格子Boltzmann模型，并发展大密度比三维多松弛时间格子Boltzmann伪势模型，对复合表面上液滴融合诱导弹跳迁移现象进行模拟。3)对功能型微纳尺度结构制备及蒸气在微纳尺度结构表面冷凝相变的综合性能开展系统研究，发明一种新型亲滑表面并开展了强化冷凝传热的实验研究，发现该新型亲滑表面上具有较高成核密度、液滴易滑动，且不凝性气体含量越高，强化冷凝传热越明显；建立了半连续超临界相反应改性实验装置和单管管外水蒸气冷凝传热实验系统，对润湿改性前后的纳米多孔陶瓷膜进行水回收和传热实验研究，明晰了典型运行参数对纳米多孔陶瓷膜冷凝及输运特性的影响规律；建立了混合湿空气对流冷凝传热实验系统，研究了大量不凝性气体存在时不同润湿性管束的冷凝传热特性，并揭示了管束效应对冷凝传热性能的强化作用。基于气液平衡理论和组分扩散原理，提出了一种局部酸露点温度计算方法，为传热表面耐酸腐蚀可靠性提供预测依据。已发表学术论文31篇，其中SCI期刊论文19篇，中文EI期刊论文2篇，国际国内会议论文10篇，作国际会议特邀报告4次、国内会议特邀报告3次，培养博士研究生5人、硕士研究生3人。