多孔黑体材料光热效应致海水蒸发过程中能质传输特性研究

Solar desalination based porous black materials with the high absorption and conversion efficiency of solar energy can directly heat the seawater on the surface layer to evaporate, which offers many advantages of high solar thermal efficiency, simple system, low heat loss and cost. Because of these merits, this new type of steam generation is promising in the fields of seawater desalination and solar energy. The new and efficient solar desalination is a complex coupled multi-physics system, covering the photothermal effect, flow and transport in the porous media, evaporation on the liquid-vapor interface, salt and vapor diffusion. Therefore, the transport and conversion characteristics play an important role in this type of solar desalination. Aiming at the nature of its physical problem, this project is directed to the experimental and theoretical studies on the multi-physics coupled transport and conversion in porous media induced by evaporation. The emphasis will be paid to the discovery of the coupling mechanism on solar-thermal conversion of porous black materials, porous scale of evaporation, interface dynamics and multicomponent transmission. The effect of structural parameters such as pore size distribution, wettability and connectivity of framework, operating parameter including of seawater salinity, ambient temperature and humidity and light intensity on evaporation rate and solar thermal efficiency will be obtained. Eventually, a theoretical model with the coupled evaporation induced by inhomogeneous heating with two-phase on the porous scale will be developed, which will promote the application and development of solar desalination.

基于多孔黑体材料太阳能海水蒸馏系统通过具有极高光热转化效率的多孔介质层直接加热表层海水致蒸发分离，具有光热利用率高、热损失小、系统简单造价低等优点，在海水淡化和太阳能应用领域中有很好的应用前景。这种新型高效太阳能海水淡化技术是一个涉及到光热效应、孔隙结构内的流体运动与传热、气-液界面蒸发、盐分扩散、蒸气传输等多场耦合的复杂体系，热质传输特性具有重要的作用。本项目将针对其热物理问题本质特征，对复杂孔隙空间内蒸发过程中多场耦合能质传递过程开展系统的实验和理论研究工作，重点揭示多孔黑体材料光热转化过程、孔隙尺度内蒸发、界面行为与多组份传输的相互耦合关系，获得多孔介质的孔隙尺寸、骨架表面浸润性和连通性等结构参数、海水盐分浓度与环境温湿度、光照功率等运行参数对蒸发速率和太阳能热利用效率的影响规律，建立孔隙尺度上非均匀加热条件下蒸发与两相流动的热质传输模型，促进太阳能海水淡化技术的应用和发

本项目基于多孔黑体材料太阳能海水蒸馏系统，对复杂孔隙空间内蒸发过程中多场耦合能质传递过程开展系统的实验和理论研究工作。完成了多孔介质内部对流换热的模拟研究，获得多孔层内能量与流场的分布规律；采用小球堆积模型分别构建了单个不规则微通道内具有自由界面的连续液柱在加热过程中的传热传质模型，并综合考虑水蒸汽的输运、热毛细对流以及界面形态变化对蒸发特性的影响；构建了一套可应用于太阳能海水淡化的孔隙结构内光热效应致蒸发过程中多元多相流动能质传输过程的数学模型，并充分考虑气液界面蒸发、水蒸气输运与盐分输运，获得了各运行参数和结构参数对蒸发效率的影响规律；设计并制作了基于生物质多孔黑体材料和基于纳米金海绵多孔黑体材料，并搭建了太阳能海水蒸馏系统进行了实验研究，考察了材料表面特性、不同蒸馏器形态设计、加热功率、盐分浓度等参数对蒸发速率和盐分结晶的影响，最后针对现有太阳能海水淡化技术的不足，设计了三种高效抗盐便携式海水淡化（净化）装置。本项目重点揭示了多孔多孔介质内蒸发、界面行为与多组份传输的相互耦合关系，获得多孔介质的孔隙尺寸、骨架表面浸润性和连通性等结构参数、海水盐分浓度与光照功率等运行参数对蒸发速率和太阳能热利用效率的影响规律，建立孔隙尺度上蒸发与两相流动的热质传输模型，促进太阳能海水淡化技术的应用和发展。