面向滴状冷凝强化的非均匀润湿性三维图案化表面设计与加工研究

High-efficiency condensation is important for improving the efficiency of heat utilization and water collection. In view of the difficulty of substantially promoting the condensation efficiency due to the relatively large size of departing dropwise condensate, a new method is proposed to improve the condensation efficiency by confining the lateral growing space of dropwise condensate and thus reducing its departing size using 3D patterned non-uniform wetting surface with convex-shaped superhydrophilic pattern array. Additionally, the feasibility of utilizing through-mask electrolysis-electrodeposition to construct the convex-shaped superhydrophilic pattern array on superhydrophobic substrates and thereby to obtain large-scale 3D patterned non-uniform wetting surfaces will be explored. Characteristic parameters of the patterned surfaces will be designed and optimized based on the theoretical study of dynamic processes of condensate nucleation, growth and movement, as well as their influence on enhancing dropwise condensation. The regulation of nucleation and growth, along with the formation rule of micro/nano structures during the fabrication process of the optimized surfaces will also be studied. In addition, the mechanism for controlling wettability and height of the constructed convex-shaped superhydrophilic patterns will be revealed. A model will be established to predict the relationship between characteristic parameters of the patterned surfaces and their effect on condensation enhancement, various processing parameters and fabricated surface quality. New technical foundation for designing and fabricating 3D patterned non-uniform wetting surfaces with enhanced dropwise condensation is expected to be established to develop new methods for high-efficiency condensation.

高效冷凝在提高热能利用率、水资源收集效率等方面意义重大。针对目前表面滴状冷凝液脱离尺寸较大，进而制约冷凝效率大幅提升的难题，提出利用非均匀润湿性三维图案化表面的上凸状超亲水图案阵列，约束表面滴状冷凝液横向生长空间，减小其脱离尺寸，提高冷凝效率，并探索利用掩模电解-电沉积在超疏水表面构建上凸状超亲水图案阵列，进而实现大面积非均匀润湿性三维图案化表面的加工。在理论分析非均匀润湿性三维图案化表面冷凝液成核、生长、运动规律及其滴状冷凝强化机理的基础上，优化设计图案化表面特征参数，进而研究掩模电解-电沉积加工优化表面的电结晶成核、生长和微纳结构成形规律，揭示所构建的上凸状图案润湿性和高度控制机理。建立描述非均匀润湿性三维图案化表面特征参数与冷凝强化效果、各加工参数与加工表面质量之间关系的模型，形成新的面向滴状冷凝强化的非均匀润湿性三维图案化表面设计和加工技术基础，为实现高效冷凝提供新方法。

滴状冷凝相变过程释放大量潜热，传热效率极高，因此在高热流密度微电子和新能源系统散热方面意义重大；此外，其作为高效的汽相-液相相变过程也可用于干旱多雾地区水资源收集。但目前表面滴状冷凝液脱离尺寸大，易失效，进而制约滴状冷凝应用推广。项目采用非均匀润湿性三维图案化表面实现了高效长效滴状冷凝新方法。利用电沉积联合碱性氧化加工出微乳突-纳米草复合结构超疏水基底实现滴状冷凝；揭示了微纳复合结构超疏水基底高密度冷凝成核、微乳突约束冷凝液横向生长，并通过挤压液滴产生拉普拉斯压力梯度驱动液滴脱离表面，进而强化滴状冷凝的机制；获得表面在过冷度0.2 K时滴状冷凝传热系数达218000 W·m-2·K-1，显著高于已知水平，且表面具有滴状冷凝长效性、优异耐电化学腐蚀和机械摩擦性能。在具有滴状冷凝特性的超疏水基底设计基础上，实现利用掩模电解-电沉积在超疏水基底自下而上构建出高度大于250 μm、润湿性/形貌可控的上凸状三维超亲液图案阵列，进而高效增材制造出大面积非均匀润湿性三维图案化表面新工艺；上凸状超亲水图案进一步约束滴状冷凝液横向生长，并通过毛细吸收、传输滴状冷凝液，从而显著减小滴状冷凝液脱离尺寸，使滴状冷凝传热效率在微纳复合结构超疏水基底基础上进一步提升85％、冷凝传热极限提高113％。此外，项目扩展研究了具有滴状冷凝行为的非均匀润湿性图案化超滑表面设计与加工，分析了超滑表面液滴动态行为及滴状冷凝强化机制。为推进滴状冷凝实际应用，开展了基于滴状冷凝强化的高性能相变散热器设计与制造研究，形成新的面向滴状冷凝强化的表面设计/制造一体化技术基础，为高效集水器件、面向先进系统的高性能相变散热器研制提供了新思路。