【作者】 黄璐；

【导师】 胡雪蛟；

【作者基本信息】 武汉大学 ， 热能工程， 2021， 博士

【摘要】 随着社会经济的快速发展,淡水和能源的日益紧迫已经成为全球高度关注的问题。相比于市场上成熟的主要依靠化石能源消耗的膜法和热法海水淡化技术,利用地球上丰富的清洁可再生太阳能进行海水淡化和发电,既能够有效缓解淡水和能源紧缺问题,又可以加快我国尽快实现碳中和的目标,是一项具有重大战略意义的工作。为了更加高效地利用太阳能进行海水淡化和发电,本文围绕着太阳能海水淡化及发电的新方法和新思路进行了深入地探究,具体的研究内容和主要结论如下:（1）提出了一种太阳能电池板余热多级海水淡化系统,利用多级膜蒸馏技术回收太阳能电池板表面的余热进行高效海水淡化,产生大量清洁的淡水。同时,采用蒸发冷却技术降低太阳能电池板表面温度,从而提高其光电转化效率。通过实验和理论两个方面对耦合系统的产水速率和降温效果进行了深入地探究。实验结果表明,在一个标准太阳光照强度和四级膜蒸馏系统下,耦合系统可以达到1.42 kg m^-2 h^-1的产水速率和提高1%的光电转化效率,与理论预测结果具有较好的一致性。为了评估耦合系统在实际应用中电水联产的性能,在一个标准太阳光照强度下,通过带有四级膜蒸馏模块的耦合系统对10Ω的外部负载提供电能的输出同时进行淡水制备,该耦合系统可以实现66.6 W m^-2的稳定电能输出,并保持稳定的1.11 kg m^-2 h^-1的产水速率。（2）设计了一种太阳能热聚焦多级海水淡化系统,解决了太阳能海水淡化蒸气温度低和冷凝潜热浪费的问题。利用太阳能热聚焦技术获得高温热源,从而产生更高温的初始蒸气,提高蒸气做功能力的同时减少了系统热损,并通过潜热回收技术来多次利用蒸气冷凝潜热。实验结果表明,在一个标准太阳光照强度下,六级蒸馏器的产水速率高达1.84 kg m^-2h^-1,是单级蒸馏器产水速率的2.5倍。当热聚焦技术与多级潜热回收系统结合使用时,在3倍热聚焦条件下,产水速率可以进一步提高到2.2 kg m^-2h^-1。最后建立了太阳能热聚焦多级海水淡化系统相对应的数学模型,研究了不同工况下系统产水速率和热效率的变化规律,获得了热聚焦多级潜热回收技术实现太阳能高效海水淡化的机理。（3）开发了一种太阳能淡化水流动机械能（水力压力能）回收系统。首先建立了太阳能膜蒸馏和淡化水压力能回收系统相应的物理模型和数学模型,理论计算表明,在40℃的跨膜温差下,该电水联产系统可实现31 kg m^-2 h^-1的产水速率,同时可以产生的最大体积功功率密度为534.6 W m^-2,对应的相对卡诺循环效率高达9.55%。为了将体积功转换为真实的高品位电能,利用PTFE疏水膜与自制的Al₂O₃动电发电膜串联,搭建了一套电水联产实验系统,在40℃的跨膜温差下,系统的产水速率可达13.5 kg m^-2 h^-1,并以147μW m^-2的功率额外输出电能,表明这种新型电水联产系统为太阳能淡化水压力能的回收提供了可行的研究方向。更多还原

【Abstract】 With the rapid development of society economy,the increasing urgency of fresh water and energy has become a global concern.Compared with the mature membrane and thermal desalination technologies on the market,which mainly rely on the consumption of fossil energy,Using the abundant clean and renewable solar energy on the earth for desalination and power generation can not only effectively alleviate the shortage of fresh water and energy,but also speed up the goal of carbon neutralization in China as soon as possible,which is a work of great strategic significance.In order to make more efficient use of solar energy for desalination and power generation,this paper focuses on new methods and new ideas of solar desalination and power generation.The specific research contents and key results are as follows:（1）A multi-stage desalination system using the waste heat of solar panel is proposed.The multi-stage membrane distillation technology is used to recover the solar panel surface waste heat for desalination to produce a large amount of fresh water.At the same time,the solar panel temperature is reduced by evaporative cooling technology to improve its photo-electric conversion efficiency.The water production rate and cooling effect of the coupling system are studied from both experimental and theoretical aspects.The experimental results show that under one sun illumination and four-stage membrane distillation system,the coupling system can achieve a water production rate of 1.42 kg m^-2 h^-1 and a 1%increase in photoelectric conversion efficiency,which are in good agreement with the theoretical calculation results.In order to evaluate the performance of the coupling system in the practical application of electricity and water co-generation,the coupling system with a four-stage membrane distillation module is used to output electric energy to an external load of 10Ωand to produce fresh water at the same time under one-sun illumination.The coupling system can achieve a stable electric energy output of 66.6 W m^-2 and maintain a stable water production rate of 1.11kg m^-2 h^-1.（2）A solar thermal concentration multi-stage desalination system is proposed to solve the problems of low steam temperature（steam grade）and waste of condensation latent heat.High temperature heat source is obtained by using solar thermal concentration technology,which can generate higher temperature initial steam to improve work ability and reduce system heat loss.Latent heat recovery technology is used to reuse steam condensation latent heat for many times.The experimental results show that the water production rate of the six-stage distiller is as high as 1.84 kg m^-2 h^-1 under one-sun illumination,which is 2.5 times of that of the single-stage distiller.When the multi-stage latent heat recovery system is combined with the thermal concentration technology,the water production rate can be further increased to 2.2 kg m^-2 h^-1 under three times of thermal concentration.Finally,a mathematical model corresponding to the solar thermal concentration multi-stage seawater desalination system is established,and the change rules of the water production rate and thermal efficiency of the system under different working conditions are studied,and the mechanism of the solar thermal concentration multi-stage latent heat recovery technology to achieve efficient solar desalination is obtained.（3）A system for recovering the flow mechanical energy（hydraulic pressure energy）of solar desalinated water is proposed.Firstly,we established the corresponding physical and mathematical models of the solar membrane distillation and pressure energy recovery of desalinated water system.Theoretical calculations show that under the temperature difference of 40℃,the electricity-water co-generation system can achieve a water production rate of 31 kg m^-2 h^-1,and the maximum volumetric work power density that can be generated is 534.6 W m^-2,and the corresponding relative Carnot cycle efficiency is as high as 9.55%.In order to convert volume work into real high-grade electric energy,a set of experimental system for co-generation of electricity and water is built by using the PTFE hydrophobic membrane and the self-made Al₂O₃electrokinetic power generation membrane in series.Under the temperature difference of 40℃,the water production rate of the system can reach 13.5 kg m^-2 h^-1,and the additional power output is 147μW m^-2,indicates that this new type of electricity and water co-generation system provides a feasible research direction for the recovery of pressure energy from solar desalinated water.更多还原