自呼吸式微型直接甲醇燃料电池非绝热模型
发布时间:2018-03-31 17:38
本文选题:自呼吸式μDMFC 切入点:模型 出处:《杭州电子科技大学》2017年硕士论文
【摘要】:和其他类型微能源不同,微型直接甲醇燃料电池(Micro Direct Methanol Fuel Cell,μDMFC)具有燃料源充足且花费小、燃料本身方便保存与随身携带、并且不存在安全隐患、构造简单且不需要原料重整和净化、以及运行条件易于实现等诸多优势,更适用于未来便携式电子产品和微型武器系统的应用,正日益受到人们的密切关注,是国际上研究的热门范畴。本文的主要工作内容如下:1、详细介绍了μDMFC,包括μDMFC的组成结构,各个结构详解,工作原理,工作过程中发生的电化学反应;以及多孔介质中两相流传输理论,包含液体的饱和度、相对渗透率、接触角、毛细压强的作用力;电池本身的特点和极化的存在及影响电池性能的关键点。为下文的三维两相模型仿真提供理论依据。2、从理论上详细分析了气液物质传输和发生反应的方程式、PEM中的甲醇和水渗透作用、电子和质子传输方法。3、提出自呼吸式μDMFC的一种新结构。建立三维两相模型并分析结果,包括各物质分布情况以及浓度分布对电池性能的影响;压强和流速分布及对电池性能的影响;饱和度分布情况及对电池的影响;电势和电流密度分布情况及对电池性能的影响;温度分布及对电池性能的影响;其他参数对电池性能的影响,从而得到较好的结构参数。4、结果表明:阳极传质与电池的性能关系最大,其次是阴极氧气传输;甲醇传输主要依靠扩散,所以物质运动流速及压强对电池性能关系较弱;甲醇的渗透会在阴极发生反应产生混合过电位,电池的性能会因此而降低;甲醇传输至阴极主要是扩散引起的,电流密度较高的时候,渗透量会变小,如果甲醇浓度变大的话,则渗透效果也会更剧烈;阳极的气压变化梯度要大于阴极的,因为阳极主要是液相物质,阴极主要是气相物质,气相物质流动性好,阴极的压强变化小;随着反应的进行,阴极会出现“水淹”现象;电子电流主要是和电流收集器结构有关,质子电流主要是随着甲醇浓度分布变化。
[Abstract]:Unlike other types of micro-energy sources, micro Direct Methanol Fuel cells (渭 DMFCs) have sufficient fuel sources and low cost, and the fuel itself is easy to save and carry around, and there is no security hazard.Many advantages, such as simple construction, no need for raw material reforming and purification, and easy to realize operating conditions, are becoming more and more suitable for the application of portable electronic products and micro weapon systems in the future.It is a hot area of international research.The main work of this paper is as follows: 1. The composition of 渭 DMFCs, including the composition of 渭 DMFCs, the detailed explanation of each structure, the working principle, the electrochemical reactions occurring in the working process, and the transport theory of two-phase flow in porous media, including the saturation of liquid, are introduced in detail.The relative permeability, contact angle, capillary pressure, the characteristics of the battery itself, the existence of polarization and the key points affecting the performance of the battery.This paper provides the theoretical basis for the simulation of the three-dimensional two-phase model below, and theoretically analyzes the methanol and water permeation in the equation of gas-liquid material transport and reaction in PEM.Electron and proton transport method. 3. A new structure of self-breathing 渭 DMFC is proposed.Three-dimensional two-phase model was established and the results were analyzed, including the distribution of various substances and the influence of concentration distribution on the performance of the battery, the distribution of pressure and velocity and the influence on the performance of the battery, the distribution of saturation and the influence on the battery.The distribution of potential and current density and its effect on the performance of the battery; the temperature distribution and the effect on the performance of the battery; and the effect of other parameters on the performance of the battery,The results show that the anode mass transfer has the largest relationship with the performance of the battery, followed by the cathode oxygen transport, and the methanol transport mainly depends on diffusion, so the relationship between the mass transfer rate and the pressure on the cell performance is weak.The permeation of methanol will produce mixed overpotential at the cathode, and the performance of the cell will be reduced. The methanol transport to the cathode is mainly caused by diffusion. When the current density is high, the permeation will become smaller, if the methanol concentration increases,The pressure gradient of the anode is larger than that of the cathode, because the anode is mainly a liquid phase material, the cathode is mainly a gas phase material, and the gas phase material fluidity is good, and the pressure of the cathode changes little; as the reaction proceeds,The electron current is mainly related to the structure of the current collector, and the proton current mainly varies with the concentration distribution of methanol.
【学位授予单位】:杭州电子科技大学
【学位级别】:硕士
【学位授予年份】:2017
【分类号】:TM911.4
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