【作者】 刘小波；

【导师】 简弃非；

【作者基本信息】 华南理工大学 ， 动力机械及工程， 2010， 硕士

【摘要】 质子交换膜燃料电池具有如下优点:其发电过程不涉及氢氧燃烧,因而不受卡诺循环的限制,能量转换率高;发电时不产生污染,发电单元模块化,可靠性高,组装和维修都很方便,工作时也没有噪音。所以,质子交换膜燃料电池是一种清洁、高效的绿色环保电源。本文使用计算机模拟的方法来分析质子交换膜燃料电池的水热管理,使用了计算流体力学软件Fluent中的PEM模块进行计算。分别建立了直流道质子交换膜燃料电池和带冷却通道的直流道质子交换膜燃料电池模型进行分析。对直流道质子交换膜燃料电池进行了模拟计算,得出工作电压越低,电流密度越大,电池内部温度越高,温差越大,质子交换膜越容易脱水,电池的工作可靠性越差,工作电压越高,电流密度越小,电池内部温度越低,温差越小,质子交换膜越不易干涸,电池的工作可靠性越强。在此基础上,探讨了加湿程度和孔隙率对燃料电池的性能及温度分布的影响,结果表明不加湿时电池前半段膜内水的摩尔浓度太低,膜脱水严重,膜容易破裂致使H2、O2混合,甚至会发生爆炸。阴极加湿水的质量分数为0.3,阳极加湿水质量分数为0.3时,整个电池膜内水的摩尔浓度都在比较合理的水平,膜的含水量适中,此时膜的润湿状况良好,电池内水平衡处于最佳状态。膜内温度分布比较均匀,膜内水含量增加,其内阻减小,膜的导电性增强,化学反应加剧,电池性能增强。改变孔隙率对膜内温度分布的影响非常小,膜内温差很小,说明孔隙率的大小不是影响电池内部温度变化的主要原因。建立了带冷却通道的直流道质子交换膜燃料电池的模型,冷却水流速为0.1m/s时,沿流道方向膜中心温度最高,冷却水流速为2m/s时,沿流道方向膜中心温度最低。冷却水流速对沿流道方向膜中心温度分布的影响比较小。冷却水温度为10℃时,沿流道方向膜中心温度最低,冷却水温度为60℃时,沿流道方向膜中心温度最高。在冷却水温度为20℃时,既可以达到冷却的目的,又不至于使初段温度过低而降低电化学反应程度。冷却水顺流时沿流道方向膜中心温度比冷却水逆流时稍低,冷却水顺流和逆流对沿流道方向膜中心温度的影响差别不大。更多还原

【Abstract】 Proton exchange membrane fuel cell has the following advantages: its generation process does not involve hydrogen-oxygen combustion, and thus not subject to Carnot cycle limit, the energy conversion rate is high; electricity without pollution, power generation unit modular, high reliability, assembly and maintenance of very convenient to work, they do not have noise. Therefore, the proton exchange membrane fuel cell is a clean, efficient green power.This article uses the computer simulation method to analyze the proton exchange membrane fuel cell thermal management of water, using computational fluid dynamics software Fluent in PEM module calculated. Flow channel were set up five proton exchange membrane fuel cells and the cooling channel 5 with a flow channel model for proton exchange membrane fuel cells for analysis.Flow channel of the five proton exchange membrane fuel cell was simulated, obtained the lower operating voltage, current density, the greater the battery internal temperature the higher the temperature the greater the proton exchange membrane, the easier dehydration, the worse the reliability of the battery’s work , the higher the voltage, current density, the smaller the battery internal temperature the lower the temperature the smaller the proton exchange membrane more difficult to dry, the stronger the reliability of the battery’s work.On this basis, to explore the extent and the porosity of the humidification on fuel cell performance and temperature distribution in the results that they do not wet the battery when the first half of the molar concentration of water is too low membrane, membrane dehydration serious, membrane rupture resulted in easy to H2, O2 mix, or even an explosion. Cathode humidification water, the mass fraction of 0.3, anode humidification water quality score of 0.3, the entire cell membrane of the molar concentration of water in a more reasonable level, the membrane water content is moderate, at this time of the wetting film in good condition, batteries water balance at its best. More uniform temperature distribution membrane, membrane water content increases, its resistance decreases, membrane conductance increased, the chemical reaction of aggravated battery performance enhancements. To change the porosity of the membrane temperature distribution is very small, very small membrane temperature, indicating the pore size is not affecting the rate of temperature change inside the main reason for the battery.Establishment of the cooling channel 5 with a flow channel of proton exchange membrane fuel cell model, the cooling water flow rate of 0.1m / s when the flow channel along the direction of the maximum membrane core temperature, cooling water flow rate of 2m / s when the flow channel along the direction of film core temperature minimum. Cooling water flow rate along the flow channel direction of the temperature distribution in film center is relatively small. Cooling water temperature is 10℃, the direction of flow channel along the membrane core temperature minimum, cooling water temperature is 60℃, the direction of flow channel along the membrane core temperature up. In the cooling water temperature is 20℃, not only to achieve the purpose of cooling, but also does not cause the temperature is too low and the lower part of the initial extent of electrochemical reaction. Cooling water flow channel along the downstream direction when the membrane core temperature lower than when the cooling water upstream, downstream and upstream of the cooling water flow direction along the membrane core temperature of not very different.更多还原