环境热量吸收与微纳结构协同增强的仿蒸腾太阳能蒸发器

Photothermal interface evaporation is a highly efficient solar energy utilization method. As a main component of photothermal interface evaporation, solar evaporator has some demerits, including low evaporation rate, poor water resistance, hard to degrade etc. Furthermore, there is a lack of research on the mechanism of the influences of heat transfer, mass transfer and interface structure on evaporation. The project intends to employ natural material-wood as raw material to develop a new kind of evaporator, to break through the theoretical evaporation limit of a standard solar light intensity (1.47 kg•m-2•h-1) to achieve an evaporation rate of seawater above 3.5 kg•m-2•h-1 through structural design of the evaporator and the absorption of environmental energy..This work plans to utilize the natural multi-stage micro-nanopore structure of wood to imitate the transpiration of trees, and regulates the thickness of the light-absorbing layer through precise carbonization of the wood surface. Through the controllable removal of lignin in the wood cell wall and plasma treatment, the permeability and size diversity of the three-dimensional tunnels, and the hydroxyl groups are increased, and to intelligently regulate the height and the rate of self-water absorption of wood, preparing a biomimetic three-dimensional solar evaporator with multi-level porous channel. The desalination effect of the designed evaporator will be tested. .The evaporation enhancement mechanism of the solar evaporator will be explained via the analysis of the effects of mass transfer, heat transfer and evaporation structure on evaporation. The implementation of this project will provide a more environmentally friendly and efficient evaporation method for seawater desalination and sewage purification, and provide theoretical guidance for the design and optimization of solar thermal interface evaporation materials.

光热界面蒸发是一种高效的太阳能利用方式，太阳能蒸发器作为光热界面蒸发的主要器件，目前存在蒸发速率低、稳定性差、难降解等问题，且热、质传输和蒸发器结构对蒸发的影响机制方面研究欠缺。项目拟以天然材料-木材为原料，通过周围环境热量吸收和微纳结构的协同增强，使蒸发器实现3.5kg•m-2•h-1以上的海水蒸发速率，远超传统认为的1个标准太阳光强度的理论蒸发极限（1.47kg•m-2•h-1）。项目模仿树木蒸腾作用，通过木材表面的精准碳化调控吸光层厚度；通过木质素的可控脱除和等离子体处理，增加羟基含量和孔的通透性、多样性，调控木材微纳结构和自吸水高度与速率，制备出仿蒸腾太阳能蒸发器，测试其海水淡化效果。通过对水、热传输和微纳结构对蒸发的影响分析，阐释蒸发增强机制。项目实施可为海水淡化、污水净化提供更环保、高效的蒸发方式，为太阳能光热界面蒸发材料设计和优化提供理论指导。

淡水短缺威胁着全球三分之二的人口，全世界有5亿人全年缺乏足够的饮用水供应。海水淡化被认为是一项有效解决这一全球性问题的重要措施。太阳能驱动的界面蒸发是一种零能耗的海水淡化方法，可实现太阳能的高效利用，太阳能蒸发器作为光热界面蒸发的主要器件，存在蒸发速率低、稳定性差、难降解等问题。本项目以天然材料-木材为原料，仿树木蒸腾作用，设计了一种三维（3D）太阳能蒸发器。通过对木材表面进行精准碳化调控吸光层厚度，碳化层的总太阳光吸收率可以高达98%。通过木质素的可控脱除和等离子体处理，增加了羟基含量和孔的通透性、多样性，处理后木材的吸水率达到1.50 g g-1 h-1。利用此仿蒸腾3D太阳能蒸发器的自吸水性能，通过调节蒸发器吸光层距离水面的高度，可以调控水在蒸发层的状态，实现毛细水状态，蒸发层的水蒸发潜热由2444 J g-1降低到1769 J g-1。即使消除了3D太阳能蒸发器的侧面蒸发，在一个太阳光强度下(1 kW m-2)下仍可达到1.93 kg m-2 h-1的高蒸发速率。在开放式系统中工作时，将侧面暴露在空气中获取环境能量，在一个太阳光强度下最大蒸发速率为3.91 kg m-2 h-1。在实际海水淡化装置中使用该3D太阳能蒸发器，其产水率是普通界面蒸发(2D)的2.2倍，证明其具有良好的实用性。此外，项目制备的仿蒸腾3D太阳能蒸发器表现出了优越的结构稳定性和盐耐久性，表明该蒸发器可以长期稳定地进行太阳能海水淡化。本项目揭示了蒸发结构对太阳能光热界面蒸发水蒸气逃逸的影响机制，摸索出的水蒸发潜热降低策略可为实际的太阳能海水淡化工程提供一种有前途的设计原理。