【作者】 裴媛；

【导师】 郭航；

【作者基本信息】 北京工业大学 ， 热能工程， 2010， 硕士

【摘要】 小型全被动式直接甲醇燃料电池没有泵和风扇等辅助元件,其参与电化学反应的阳极甲醇溶液和阴极的氧气均依靠扩散实现,在体积、重量以及自身耗电等方面有较大幅度的降低,但其内部传质不佳是电池输出性能低的一个重要原因。此外,可在任意角度下正常运行是其用于小型便携式电源的要求。本文针对被动式微小型直接甲醇燃料电池开展了不同角度下的极化曲线和动态响应特性的实验研究工作,主要研究成果如下:1对本课题组第一代小型全被动式直接甲醇燃料电池的结构进行了改进,电池改进的部分主要包括甲醇储液罐外壳、甲醇储液罐以及定位板,同时还增加了加热及温度控制系统;2实验研究了运行温度、甲醇溶液浓度以及电池放置倾角等参数对小型全被动式直接甲醇燃料电池静态性能的影响,同时对电池静态放电过程中的阴极凝水展开了实时可视化观测。实验结果表明:(1)温度的升高导致不同开孔率电池的极限电流密度随之升高,与之相对应的阴极凝水量也增加,但电池受温度影响的程度随甲醇溶液浓度的升高而降低;(2)甲醇溶液浓度影响着小型全被动式直接甲醇燃料电池的输出性能,在低浓度时,-45°倾角的电池在浓差极化区的性能最高,阴极凝水量最少,而45°倾角的电池在浓差极化区性能最差,阴极凝水量最多,但是随着甲醇溶液浓度的升高,电池受角度影响的程度逐渐降低。3研究了开孔率不同时小型全被动式直接甲醇燃料电池的静态性能及动态响应特性:(1)随电流强度的升高,40%极板开孔率的电池燃料供应相对于25%极板开孔率时更稳定,极限电流密度也相对要高;(2)电流密度按照不同波形在加载高电流强度过程中,25%开孔率电池的燃料供应不足较为明显;4考察了不同甲醇溶液浓度的小型全被动式直接甲醇燃料电池按照不同的加载波形、加载斜率以及加载强度时电压的动态响应特性,并且深入分析了小型全被动式直接甲醇燃料电池的电流强度动态变化时的电池内部传质特性,探讨了倾角对小型全被动式直接甲醇燃料电池动态响应的影响。更多还原

【Abstract】 Miniature passive direct methanol fuel cell do not have any pump and fans. The reactant of electrochemical reaction including methanol solution in anode and oxygen in cathode, are mainly transported by diffusion. Its volume, weight and electricity power consume by itself have been reduced by a large margin. But mass transfer resistance inside fuel cell causing little power is one of the most important reasons of output performance degradation of the fuel cell. In addition, portable power sources require that the fuel cell could oprate on and orientation. In this paper, experimental study about small passive direct methanol fuel cell operating at different angles of polarization curves and its dynamic response was in progress, the main research results are as follows:1 The first generation of small passive direct methanol fuel cell in our group was improved. Some of the main improvements including: methanol tank shell, methanol tank and the positioning plate, also increased the heating and temperature control system;2 The influence of temperature, methanol concentration, placement angle and other operating parameters on small passive direct methanol fuel cell was stuied. At the same time, in-situ visualization was carried out during static discharging, the results showed that:(1) Limiting current density of small passive direct methanol fuel cell with different opening ratio increased with temperature rising, corresponding to this, the cathode condensate water had also increased, but the extent of fuel cell affected by temperature with the increase of methanol concentration degraded;(2) Methanol solution concentration affected the small passive direct methanol fuel cell output performance. With the low concentration methanol solution, the performance of fuel cell at -45°in the concentration polarization was better than other cases, the amount of water condensate in the cathode was the least. But fuel cell at 45°was on contrary.3 Static performance and dynamic response of small passive direct methanol fuel cells with different opening ratio of polar plate was investigated.(1) With the current loading intensity increases, fuel supply in small passive direct methanol fuel cells with the opening rate of 40% was more stable than fuel cell which polar plate with 25% opening ratio, and its limiting current was higher.(2) While current loading in different waveforms, output voltage at high current loading intensity of the fuel cell in different wave was completely different. 25% opening ratio of the fuel cell was more obvious in short supply.4 It explored the dynamic response characteristics of small passive direct methanol fuel cell while loading in different waveforms and different slopes, and analyzed the mass transfer characteristics inside fuel cell when the current loading intensity changed.更多还原