醌溴液流电池非稳态非等温过程的数值模拟

发布时间：2018-04-18 14:58

本文选题：醌溴液流电池 + 数值模拟　；参考：《北京理工大学》2015年硕士论文

【摘要】：近年来,伴随着不可再生能源危机加剧,以可再生能源逐步替代不可再生能源是未来一种发展趋势。然而可再生能源自身带有间歇性,这种不稳定性存在着很大的安全隐患。由于大规模储能技术能够起到削峰填谷的作用,提高电网的安全性,所以各国对大规模储能电池的研究也越来越重视。以无机物做电解质溶液的传统液流电池,受限于金属量,不可长期广泛使用。本课题研究的是一种新型有机醌溴液流电池,该种液流电池不使用金属物质,所以不受资源量的限制,而且以有机物做电解质材料,可以根据需要对所用有机物分子结构进行改进和修饰。文中使用Comsol Multiphysics软件,耦合了三大普遍守恒方程以及电极反应动力学方程,建立了数值模型,并且对模型进行了验证和分析。研究结果表明,流道结构影响电流密度的分布和电解液传质,所以对电池性能有很大影响。因为流道结构的存在,使得多孔电极上的电流密度分布不均匀,同时受物质传质的影响,在电池的边角位置会出现反应物浓度偏低,产物积累,过电位偏离较高的现象,加大了极化程度和电能损失。通过调整工艺参数发现,小电流密度进行充放电时,极化程度较小,电池内部的欧姆降也较小,电池性能较好,但是完成一次充放电耗时较长。小电流密度时,流率对电池性能影响非常小。增大孔隙率,可以加快电化学反应,相应的也会加强浓差极化。在一定温度区间内,温度越高电池性能越好,但当达到一定温度后,提高温度对电池性能基本没影响,电流大小与电池内部能量变化密切相关,大规模储能时,为实现最大经济效益可根据不同季节以及充放电电流大小来综合考虑是否需要温度调控系统。通过对课题组所做醌溴液流电池溴透过实验的探究,建立了数值模型,发现溴以三种传质方式穿过膜时,以扩散为主要方式,通过降低过量的正极电解质溶液浓度的方法,可以降低溴透过量,提高电池库伦效率,同时调大负极侧电解质溶液流率,降低正负极两侧压差,也能有效的降低溴透过量,提高电池库伦效率。
[Abstract]:In recent years, with the aggravation of non-renewable energy crisis, it is a development trend to replace non-renewable energy with renewable energy gradually.However, renewable energy itself has intermittent nature, such instability has a great security risk.Because the large-scale energy storage technology can play the role of cutting the peak and filling the valley, improve the security of the power grid, so the research of large-scale energy storage battery has been paid more and more attention.The traditional liquid-flow battery with inorganic substance as electrolyte solution is limited by metal content and cannot be widely used for a long time.In this paper, a new type of organic quinone bromine liquid flow battery is studied, which does not use metal substance, so it is not limited by the amount of resources, and uses organic substance as electrolyte material.The molecular structure of organic compounds can be modified and modified according to the need.In this paper, three general conservation equations and electrode reaction kinetics equations are coupled with Comsol Multiphysics software, and the numerical model is established, and the model is verified and analyzed.The results show that the flow channel structure affects the distribution of current density and the mass transfer of electrolyte, so it has a great effect on the performance of the battery.Because of the existence of flow channel structure, the distribution of current density on the porous electrode is not uniform. At the same time, due to the influence of mass transfer, the concentration of reactant is low, the product accumulates and the overpotential deviates from the higher one in the side corner of the battery.Increased polarization and power loss.By adjusting the process parameters, it is found that the polarization degree is small, the ohmic drop in the battery is smaller and the performance of the battery is better when charging and discharging with low current density, but it takes a long time to complete one charge and discharge.When the current density is low, the effect of current rate on the performance of the battery is very small.The electrochemical reaction can be accelerated by increasing porosity, and the concentration polarization will be strengthened accordingly.In a certain temperature range, the higher the temperature, the better the performance of the battery. However, when the temperature reaches a certain temperature, the increase of temperature has no effect on the performance of the battery, and the current is closely related to the change of internal energy of the battery, and when the energy is stored on a large scale,In order to realize the maximum economic benefit, the temperature control system can be considered synthetically according to different seasons and the current of charge and discharge.A numerical model of bromine permeation of quinone bromine liquid battery was established. It was found that when bromine was passed through the membrane in three different ways, diffusion was the main way and the concentration of excess positive electrolyte solution was reduced.It can reduce the amount of bromine permeation, improve the efficiency of the cell, increase the flow rate of electrolyte solution on the anode side, reduce the pressure difference between the positive and negative electrode, reduce the amount of bromine permeation, and improve the efficiency of the cell.
【学位授予单位】：北京理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM912

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