辐射吊顶空调超疏水换热表面凝露过程及抑露特性研究

The radiant ceiling air-conditioning system is widely concerned due to better thermal comfort and sanitary conditions, however, there is a condensatioin risk on the heat exchange surface in the application so that the higher surface temperature to be maintained, which leads to the lower cooling capacity. Therefore, prevention of the surface condensation is the key to the successful application of the system. The superhydrophobic surface can delay the formation and growth of the liquid nucleus, and effectively inhibit the surface condensation. This project will focus on the microstructure of the superhydrophobic surface, and explore the influence of microstructure of superhydrophobic surface on the formation and growth of liquid nucleus, through the study of the heat and mass transfer process under three-phase contact between the liquid nucleus and surface microstructure, meanwhile contact line dynamic change. And will study on the properties of heat exchange surfaces of different microstructure , and obtain the optimization method of surface microstructure through building the microstructural model of superhydrophobic surface. And will study on the law of heat and mass transfer in the process of droplet growth through building the mathematical model to dynamic simulate the droplet growth and coagulation process on the surface of different micro-nano structures under the condition of changing dew point,and obtain the condensation characteristics of different micro-nano structures surface under the condition of changing dew point while taking the drop diameter of droplets as the evaluation object.The above research will achieve the purpose of reducing surface temperature , improving heat transfer capacity and improving thermal comfort conditions without condensation on heat exchange surface,and provide a theoretical basis for inhibit condensation on the the heat exchange surface of radiation ceiling air-conditioning.

辐射吊顶空调系统由于热舒适性及卫生条件较好受到人们广泛关注，但在应用中存在换热表面凝露风险，需要保持较高的表面温度，这导致其供冷能力较低，因此，抑制表面凝露是系统成功应用的关键。超疏水表面能延迟液核形成与生长过程，有效抑制表面凝露。本项目从超疏水表面微观结构出发，通过研究液核与表面微观结构之间三相接触且接触线动态变化条件下的传热传质过程，探索超疏水表面微观结构对液核形成与生长过程的影响规律；通过建立超疏水表面微观结构模型，研究不同微观结构的换热表面抑露特性，获得表面微观结构优化方法；通过建立数学模型动态模拟变露点条件下不同微纳结构表面上的液滴生长与凝并过程，研究液滴生长过程的传热传质规律，以液滴跌落直径为评价对象，获得不同微纳结构表面变露点条件下的凝露特性。通过上述研究，在换热表面不凝露条件下实现降低表面温度，提高换热能力，改善热舒适条件的目的，为辐射吊顶空调换热表面抑露提供理论基础。

辐射吊顶空调系统由于热舒适性及卫生条件较好受到人们广泛关注，但在应用中存在换热表面凝露风险，需要保持较高的表面温度，这导致其供冷能力较低，因此，抑制表面凝露是系统成功应用的关键。超疏水表面能延迟液核形成与生长过程，有效抑制表面凝露。.采用微秒激光加工方法在铝合金表面获得微纳米级的粗糙结构，随后将刻蚀后的样品放入硬脂酸、软脂酸、十四酸、月桂酸溶液中静置、干燥，用自组装方法制备4种碳长链烷烃酸自组装膜，发现铝合金表面的微纳结构和碳长链烷烃酸的非极性基团是超疏水的关键。基于吉布斯自由能理论和分子动力学理论对水蒸气在过冷表面凝结成核过程进行研究，建立考虑表面润湿性和环境参数的冷辐射板表面成核速率理论模型，采用铝合金制备了亲水表面、疏水表面和超疏水表面，对样品表面液滴凝结过程进行显微观察，发现经激光刻蚀和硬脂酸改性铝合金表面具有良好的抑露性能，通过采用大表面接触角的表面能有效抑制表面结露。.冷辐射板在结露初期的单个液滴生长速率，受环境空气的温湿度、环境空气的风速、冷辐射板表面温度、冷辐射板表面材料结构等影响，项目基于传热学与分子动力学建立了辐射空调环境下单个液滴冷凝-蒸发过程传热传质分层模型，结合实验测试，分析了空调环境下冷辐射板表面结露后，液滴在冷凝与蒸发过程中的尺寸变化，并制作了光滑及激光刻蚀两种铝合金表面分别进行液滴冷凝与蒸发实验，发现激光刻蚀疏水铝合金表面的液滴覆盖率仅为同时刻下光滑铝合金表面的一半，延缓结露效果显著，为辐射空调系统防结露提供指导。.项目采用实验与数值模拟相结合的方法，对露点突变条件下辐射吊顶空调系统微纳结构换热表面凝露特性进行了研究，获得了诱导型贴附射流、地板型上送等两种新风系统在运行过程中辐射板贴附层露点温度的变化特性，分析了室内人员突增和改变新风量对辐射板贴附层露点温度分布特性的影响，为解决辐射顶板空调系统露点突变条件结露问题提供了支撑。