聚合物-多孔陶瓷复合膜逆流露点间接蒸发冷却器传热传质机理的研究

How to solve the driving temperature difference of the indirect evaporative cooling is limited by the wet bulb temperature, one of the key scientific problems in the research field of evaporative cooling at home and abroad is making the supply air (water) temperature approach to the dew point temperature.At present, the main materials of the current dew point indirect evaporative cooler are pure metal materials, polymer materials or porous ceramics, each of which has its corresponding advantages and disadvantages，but lack a kind of dew point indirect evaporative cooler which makes varieties of materials’ characteristics optimized and composites them as a whole and uses the counter current heat transfer, and related research of heat and mass transfer mechanism. New type of dew point indirect evaporative cooler proposed in this paper is made by polymer-porous ceramic composite membrane.The surface of high molecular polymer is coated a layer of porous ceramic membrane with high porosity, small volume density, large specific surface area, high thermal conductivity, good hydrophilicity, strong durability, excellent capillary effect as the surface of the wet channel to retain moisture and achieve efficient heat and moisture exchange.At the same time, the counter current heat and mass transfer method is adopted to reduce the structure size of the heat exchanger.. This paper intends to use fractal theory to describe the microscale spatial structure of porous ceramic medium, build the fractal equivalent element model , and the heat and mass transfer model of polymers - porous ceramic composite membrane ,and research the heat and mass transfer mechanism of dew point indirect evaporative cooler combining with simulation and experimental research methods; discussing the affections of porous ceramic medium nanoparticle fractal diameter on heat and mass transfer processes, and optimize design and analysis the new dew point indirect evaporative cooler structural parameters, etc.

本课题旨在解决间接蒸发冷却降温的驱动温差受湿球温度限制，使蒸发冷却空调的送风（水）温度逼近露点温度这一国内外蒸发冷却研究领域主攻关键科学问题。现有的冷却器选材主要是单一的金属、纤维等材料。每种材料都有其各自的优缺点，而缺乏将各种材料特性加以优化复合为一体且采用逆流传热传质方式，以及相关的传热传质机理的研究。本课题提出的新型露点间接蒸发冷却器，是以高分子聚合物-多孔陶瓷复合膜为传热传质材料，在高分子聚合物表面涂敷一层多孔陶瓷膜，作为换热器湿通道的壁面，以提高蒸发冷却的热湿交换效率。同时采用逆流传热传质等方式，以减小换热器的结构尺寸。本课题拟采用分形理论，描述多孔陶瓷介质微尺度空间结构，建立分形等效单元模型及聚合物-多孔陶瓷复合膜的传热传质模型，并结合模拟与实验研究等方法，研究该新型冷却器的传热传质机理；探讨多孔介质纳米颗粒分形直径对传热传质过程的影响；并优化设计和分析该冷却器的结构参数。

蒸发冷却空调因其高效的节能效果在炎热干燥地区的应用越来越受到人们的关注。然而现阶段蒸发冷却空调产品普遍面临着以下的技术障碍：1.较低的冷却效率；2.较低的温降幅度；3.较大的设备体积；4.对周围环境较高的依赖度。这些技术障碍大大制约了蒸发冷却空调的推广与应用。本课题旨在解决间接蒸发冷却降温的驱动温差受湿球温度限制，使蒸发冷却空调的送风（水）温度逼近露点温度这一国内外蒸发冷却研究领域主攻关键科学问题。现有的冷却器选材主要是单一的金属、纤维等材料。每种材料都有其各自的优缺点，而缺乏将各种材料特性加以优化复合为一体且采用逆流传热传质方式，以及相关的传热传质机理的研究。本课题提出的新型露点间接蒸发冷却器，是以高分子聚合物-多孔陶瓷复合膜为传热传质材料，在高分子聚合物表面涂敷一层多孔陶瓷膜，作为换热器湿通道的壁面，以提高蒸发冷却的热湿交换效率。同时采用逆流传热传质等方式，以减小换热器的结构尺寸。本课题采用分形理论，描述多孔陶瓷介质微尺度空间结构，建立分形等效单元模型及聚合物-多孔陶瓷复合膜的传热传质模型，并结合模拟与实验研究等方法，研究该新型冷却器的传热传质机理。同时探讨多孔介质纳米颗粒分形直径对传热传质过程的影响，并优化设计和分析该冷却器的结构参数。最后通过露点间接蒸发冷却器性能实验综合测试，最终对露点间接蒸发冷却器的结构参数进行优化设计与分析，以提高蒸发冷却效率，降低空调能耗及耗水量，解决蒸发冷却产出空气（水）温度逼近露点的能效提升问题。