超疏水毫米尺度阵列表面强化滴状冷凝传热的机理研究

Dropwise condensation is an efficient mode that significantly increases heat transfer efficiency and, dropwise condensation on superhydrophobic surfaces is, currently, becoming a hot research topic. In this project, a type of superhydrophobic millimeter-scale post arrays with much larger surface area is designed to enhance the surface heat transfer performance by increasing the number of nucleation sites and enhancing drop self-removal. The relational model between the motion of condensate drops and surface structure parameters will be constructed and a surface multi-objective optimization method to enhance simultaneously drop nucleation and self-removal will be proposed. A two-step method combining micromachining and chemical etching is proposed to prepare the copper-based superhydrophobic millimeter-scale post arrays in a fast manner. The influence of enhancing drop nucleation and self-removal on condensation heat transfer coefficient on the surface is obtained from the experiments, and a new model suitable for condensation heat transfer on the as-fabricated surface is built to reveal the structure-function relationship between the surface and heat transfer. The theories and technical implementation of this project will have important scientific and practical significance to enrich and improve the theory of condensation heat transfer, and meanwhile afford new approaches and mindset for designing energy-saving surface with high-efficiency condensation heat transfer performance.

滴状冷凝是一种高效传热方式，超疏水表面上滴状冷凝传热已成为目前国内外研究的热点。本项目提出从增加单位面积液滴成核点数目和强化液滴自驱离两方面增强表面冷凝传热性能的方案，设计大比表面积超疏水毫米尺度阵列表面。建立冷凝液滴运动与毫米尺度阵列表面结构参数之间的关系模型，提出同时强化液滴成核和自驱离高效冷凝传热表面结构参数的多目标优化方法。采用微机械加工和化学刻蚀两步法，快速制备铜基超疏水毫米尺度阵列新表面。结合冷凝传热实验，获得表面强化液滴成核和自驱离对冷凝传热的影响规律，建立新的适用于滴状冷凝的传热模型，揭示超疏水毫米尺度阵列表面与冷凝传热的构效关系。项目研究的理论成果、技术实现方法，可进一步发展和完善冷凝传热理论，为设计高效冷凝节能表面提供新的方法和思路。

超疏水表面因对水的极端排斥性在高效滴状冷凝传热领域具有广泛的应用前景。本项目主要围绕超疏水表面跨尺度液滴（微米冷凝液滴和毫米/亚毫米宏观液滴）的快速脱离及其在传热方面的基础应用方面开展研究。研究了超疏水凹曲面曲率强化液滴合并弹跳的作用规律。实验发现，当基底曲率半径和液滴半径相当时液滴合并强化作用最显著。搭建了多功能温湿度控制箱，研究了不同曲率基底和过冷度下冷凝液滴的生长、合并和脱落规律，揭示了凹曲面强化换热的机理。研究了不同尺度和排布规律的阵列结构对碰撞液滴铺展、收缩、弹跳动态及固液接触时间的影响规律，揭示了固液接触时间减少的内在机制。项目的研究成果对新型高效冷凝换热表面的设计具有重要指导意义。以上研究成果在国内外学术期刊上发表论文9篇，其中SCI论文7篇，EI论文2篇；申请发明专利3项（授权1项）；培养硕士生3人（协助培养1人），协助培养博士生1人。