仿生非均匀润湿性表面结露和融霜微滴动态传递特性研究

Solving traditional problems through bioinspired nanotechnology is an interdisciplinary forward-looking subject in air conditioners with low heat transfer efficiency and high energy consumption. Study of microscale transfer behavior of condensate and frost on the bioinspired surfaces is an important fundamental research in materials science. In this project, a nanoporous suerphydrophobic coating with wedge-shape superhydrophilic patterns will be fabricated on fin surfaces to obtain biomimetic heterogeneous wettability by modification and spray-coating of nano-chains solution, selective hydroxylation and deposition. We emphasis on studying the self-propelling characteristics of condensed and defrosting microdrops on the superhydrophobic area. According to the models of the nanoporous structure and the thermodynamic energy of the drops, we will correlate the key structure size and the transportation phenomena. Subsequently, the directional spontaneous movement of microdrops will be described on the wedge-shape superhydrophilic area. Explained from the influence of wedge shape and wettability on moving forces of drops, the reason of the dynamic performance will become clear on the superhydrophilic area. We then observe the mutual influence and reveal the change mechanism of drop dynamic transportation between the superhydrophobic area and the superhydrophilic patterns. A comprehensive model will be put forward to understand the overall dynamic transportation behavior. The results can not only provide fundamental knowledge of energy conservation and consumption reduction for low-temperature and refrigeration industry by bioinspired nanotechnology, but also display new insights to heat transfer by vapor condensation, thus showing tremendous scientific significance.

将仿生纳米技术用于解决空调传热效率低、能耗高等传统问题，是一个多学科交叉的前沿性课题；探索仿生材料表面露和霜的微观传递特性，则是材料科学领域的重要基础研究。本项目拟综合利用纳米链改性与喷涂，选区羟基化和沉积技术，研究构筑具有多孔纳米涂层超疏水区和楔形阵列超亲水区的仿生非均匀润湿性表面。分析超疏水区结露和融霜微滴自驱弹跳等动态特性，建立涂层形貌和微滴热力学能量变化的数理模型，揭示关键形貌特征参数的影响机理。研究楔形超亲水区微滴定向自驱输运等传递规律，建立与楔形几何特征参数和润湿性相关的输运作用力模型，阐明微滴传递机理。在上述基础上，进一步研究两区相互影响时，微滴动态传递特性的变化行为及机理，建立非均匀润湿性表面微滴的动态传递模型。项目研究不仅能为仿生纳米技术用于低温、制冷领域节能降耗奠定理论基础，同时可为冷凝传热等研究提供新思路，具有重要的科学意义。

水汽相变引起的结露和结霜是空调换热器低温部件表面传质传热过程中普遍存在的现象，探索将仿生表面材料用于解决该问题，是一个多学科交叉的前沿性课题。本项目基于沙漠甲虫和仙人掌集水原理，采用无掩膜光催化技术、树脂包裹颗粒杂化技术、反应离子刻蚀技术以及光刻技术等手段，制备了利于强化结露且露滴易脱附的多种仿生非均匀润湿性表面。通过表面微滴/融霜动态脱附特性和凝露集水特性的深入研究，建立了仿生非均匀润湿性表面的微滴/融霜热力学能量变化的数理模型，揭示了亲水微区几何特征和润湿性对微滴运动的作用力模型，阐明了其定向传输机理及定向脱附机制。研究结果表明，通过表面亲水微区调控可获得同时兼顾高效结露及快速露滴脱附的仿生非均匀润湿性表面。通过引入疏水楔形阵列凸起，由于水滴在楔形表面受到拉普拉斯压力梯度及非对称表面粘附的影响，凝露水滴可在楔形图案化表面定向弹跳及传输，且当楔形尖端朝上放置时，其表面凝露集水效率相对于超疏水表面提高一个数量级。通过亲水树脂对杂化颗粒进行包裹，可使非均匀润湿性涂层表面的凝露集水效率相比于超疏水表面提高二倍以上。将这种涂层修饰于纤维表面，露滴可通过自驱合并弹跳、纤维弹性振动脱除等方式脱离表面，微滴脱除效率相对于固体表面有进一步提高。同时，这种涂层还具备较好的油/水自清洁效应和融霜脱附效果，有效解决了非均匀润湿性表面抗污能力较差的问题，为开发成本低、工艺简单、抗污能力强、融霜易脱附并利于规模化生产的高效露霜微滴传递材料提供了技术支持和理论依据。项目研究为仿生纳米技术在集水、换热、脱盐、微流体控制等领域的应用提供了研究基础和参考思路，具有一定的应用推广前景及科学意义。