碱性阴离子交换膜燃料电池水热管理的实验及仿真研究

发布时间：2018-03-16 01:37

本文选题：碱性阴离子交换膜燃料电池　切入点：水热管理　出处：《天津大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着人类社会的发展,人们对能源效率及环境保护的要求越来越高,燃料电池以其启动快、效率高、噪声低、污染小的特点得到了越来越多的关注。在燃料电池中,碱性阴离子交换膜燃料电池(Alkaline membrane fuel cell,AMFC)具有较高的电化学动力学特性、较低的贵金属催化剂依赖性以及较好的二氧化碳耐受性。因而,近年来受到了国内外广泛的讨论与研究。在AMFC的研究领域中,水热管理是制约其性能、成本和耐久性的关键因素之一。因此,研究其中的水热管理问题及传热传质过程,对了解AMFC工作机理、制定水热管理策略具有十分重要的意义。首先,本研究通过制备AMFC膜电极、组装燃料电池、搭建实验系统,在不同工况条件下测试了AMFC的性能。结果表明,AMFC的激活过程分为两个阶段,第一个阶段为性能提升阶段,第二个阶段为性能衰减并达到稳定的阶段。同时,阴阳两极进气加湿能十分显著地提升电池性能,并且阴极进气加湿的作用更为明显。此外,负载的增加和减小分别会引起电流密度的过冲和下冲,而且过冲及下冲的幅度会随着负载变化的增加及加载时间的缩短而加剧。其次,为了进一步了解AMFC的水热管理及传热传质机理,本研究建立了AMFC全电池的三维多相流数值模型。该模型模拟了电池内部的化学反应、质量传输、动量传输、能量传递和水的相变等过程,并与实验结果吻合较好。再次,通过建立的AMFC三维多相流数值模型,本研究分析了稳态条件下阴阳两极进气加湿、工作温度、膜厚度和膜电极疏水性等工况条件及设计参数对燃料电池性能及传热传质过程的影响。研究发现,阳极进气加湿可以提升AMFC性能,但其作用会随着加湿程度的增加而减弱。阴极进气加湿对性能的提升作用更加显著,并且高负载条件下,阴极流道中的液态水供给会进一步提高电池性能。最后,本研究分析了AMFC对负载、阴阳两极进气加湿、工作温度等工况的动态响应。在循环负载工况中,负载的加载顺序对AMFC的性能有一定影响,并且加湿程度越低,影响越显著。此外,由阴阳两极进气相对湿度降低引起的膜态水及液态水的去除速度要快于由相对湿度增加而引起的补充速度。
[Abstract]:With the development of human society, more and more attention has been paid to the energy efficiency and environmental protection. Fuel cells have attracted more and more attention because of their characteristics of fast start-up, high efficiency, low noise and low pollution. Alkaline membrane fuel cell has higher electrochemical kinetic characteristics, lower noble metal catalyst dependence and better carbon dioxide tolerance. In recent years, it has been widely discussed and studied at home and abroad. In the research field of AMFC, water and heat management is one of the key factors restricting its performance, cost and durability. It is of great significance to understand the working mechanism of AMFC and to formulate the strategy of hydrothermal management. Firstly, through the preparation of AMFC membrane electrode, the fuel cell is assembled and the experimental system is built. The results show that the activation process of AMFC is divided into two stages: the first stage is the performance improvement stage, the second stage is the performance decay and reach the stable stage. The effect of cathode inlet humidification is more obvious. In addition, the increase and decrease of load will cause overshoot and downrush of current density, respectively. Moreover, the amplitude of overshoot and downrush will be aggravated with the increase of load change and the shortening of loading time. Secondly, in order to further understand the mechanism of hydrothermal management and heat and mass transfer of AMFC, In this paper, a three-dimensional multiphase flow numerical model of AMFC whole cell is established. The model simulates the chemical reaction, mass transfer, momentum transfer, energy transfer and phase transition of water in the battery, and the results are in good agreement with the experimental results. Based on the numerical model of AMFC three-dimensional multiphase flow, the humidification and working temperature of Yin and Yang inlet air under steady condition are analyzed. Effects of operating conditions such as membrane thickness and hydrophobicity of membrane electrode and design parameters on the performance of fuel cell and heat and mass transfer process. It is found that anode inlet humidification can improve the performance of AMFC. But its effect will weaken with the increase of humidification degree. The effect of cathode inlet humidification on performance is more significant, and the liquid water supply in cathode channel will further improve the performance of the battery under high load conditions. In this paper, the dynamic response of AMFC to the load, the inlet air humidification of both yin and yang, the working temperature and so on is analyzed. In the cyclic load condition, the loading sequence of the load has a certain influence on the performance of AMFC, and the wetting degree is lower. In addition, the removal rate of membrane water and liquid water caused by the decrease of relative humidity of inlet air between the two poles is faster than that caused by the increase of relative humidity.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM911.4

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