摘要
反向电渗析热机技术通过"热能-化学势能"和"化学势能-电能"两个转化过程完成电力生产,是一种新型的低品位余热利用技术.热机由发生单元及反向电渗析电池单元构成,分别对应上述两个转化过程.其中,发生单元对系统性能有显著影响,故本文从提升发生单元效率和系统性能出发,系统地综述了发生单元工质和发生方法的研究进展.通过探究溶剂和溶质特性对发生单元及系统性能的影响机理,凝练出工质筛选原则:反向电渗析热机适合于低汽化潜热、低沸点、高活度系数和高电导率的工质.调研发现,现有发生方法主要有蒸馏法、膜蒸馏法和热分解法,其中蒸馏法为最常见的发生方法.3种发生方法的效率较低,不可逆损失大,未来研究可聚焦于系统最优浓度梯度的构建以及发生单元与发电单元的参数匹配.此外,反向电渗析热机技术除了设计用于回收低品位工业余热,亦可用于回收太阳能和地热能等中低品位可再生能源,促进新能源的高效利用.同时,热机工作时伴随有电极反应,表明采用反向电渗析热机进行发电的同时,亦可进行污水处理、有机物降解、制氢及废酸、废碱中和处理.
The reverse electrodialysis heat engine(REDHE)has emerged as a promising technique in the waste heat harvest field due to its ability to convert very low-grade waste heat(below 100℃)into power.A REDHE consists of a regeneration unit and a reverse electrodialysis(RED)cell unit,which are in charge of heat to the salinity gradient energy-conversion process and salinity gradient to the power conversion process,respectively.Despite the fact that a regeneration unit accounts for 60% to 70% of the energy destruction of the overall system,most of the research conducted on RED units has barely reviewed the regeneration units.Therefore,the evaluation of regeneration units is necessary.This work provides a review of the research progress made on regeneration units.In this paper,a systematic review of the operating fluids and regeneration methods employed in a regeneration unit is provided.Also,the effects of solvent and solute characteristics on the performance of a regeneration unit and the overall system and the working fluid selection principle are investigated.Additionally,the disadvantages of the methods employed in existing and future development directions are analyzed.Finally,other applications of the heat engine(apart from power production)are presented.Since the RED technology has been primarily used to recover blue energy,its operating fluid is the NaCl aqueous solution.However,the NaCl solution is not suitable for the REDHE technology.Specifically,it is not suitable for the regeneration process of a regeneration unit because the latent heat of water vaporization is huge,which leads to huge energy consumption in the regeneration module.Also,the power generation performance of the NaCl solution is poor,and the maximum power density is only 1/8 of that of the Li Br solution,resulting in the low efficiency of the overall system.Since the REDHE technology is used to recover low-grade heat energy,its regeneration unit adopts a low-temperature separation technology.The main regeneration methods used are distillation separation and membrane distillation separation.The distillation separation technology is the most mature,but it consumes more energy and has a high maintenance cost.On the other hand,the regeneration temperature of the membrane distillation technology is low,but the required technology is difficult to apply,and the cost of the membrane is high.It should be noted that the biggest difference between the REDHE and traditional separation technologies is that the former aims to build an optimal concentration gradient for the battery cells,rather than to perform the complete separation of components.For example,the seawater desalination process assumes that the separated water is pure water.For an RED cell,if the diluted solution is pure water,the battery performance will decline rapidly due to the decrease in the solution conductivity.Currently,more research work has been conducted on various separation technologies and less on the coupling of regeneration technology with power generation technology.Future research should focus on the coupling of the thermal separation module with the power generation module.Although the objective of the REDHE technology is to utilize the industrial waste heat,the heat-source temperature can be very low(down to 40℃),which means that the technology can also be used for low-grade heat recovery such as geothermal and solar energy.At the same time,although the technical efficiency of the REDHE is low,its power generation process is accompanied by electrode reaction and temperature change.This means that during power generation,the REDHE can also be used for sewage treatment,organic matter degradation as well as waste acid and alkali recovery.
作者
刘子健
鹿丁
白银
孔祥玉
闻利平
公茂琼
Zijian Liu;Ding Lu;Yin Bai;Xiangyu Kong;Liping Wen;Maoqiong Gong(Key Laboratory of Cryogenics,Technical Institute of Physics and Chemistry,Chinese Academy of Sciences,Beijing 100190,China;School of Engineering Science,University of Chinese Academy of Sciences,Beijing 100049,China;CAS Key Laboratory of Bio-inspired Materials and Interfacial Science,Technical Institute of Physics and Chemistry,Chinese Academy of Sciences,Beijing 100190,China)
出处
《科学通报》
EI
CAS
CSCD
北大核心
2021年第30期3811-3821,共11页
Chinese Science Bulletin
基金
国家自然科学基金(51625603)资助。
关键词
反向电渗析
热机
余热利用
工质筛选
发生方法
reverse electrodialysis
heat engine
waste heat recovery
working fluids selection
regeneration methods
