气体扩散层结构对PEMFC性能影响二维数值模拟

质子交换膜燃料电池在运行过程中反应物从流道传输至催化层时会经过气体扩散层,气体扩散层即 可用来传输反应气体,又用来排出反应物生成的水,所以探究气体扩散层的结构对参加反应的物质及生成物 传输的影响规律有助于了解其分布情况。通过数值模拟比较了穿孔型、树状型和不规则形状气体扩散层在不 同孔隙率下顺流流动时对电池性能的影响情况。计算结果表明,气体扩散层结构严重影响质子交换膜燃料电 池性能,三种不同形状的气体扩散层对应的电性能随孔隙率的变化规律各不相同,到达催化层表面氧气的含 量受扩散层结构影响比氢气大,气体扩散层结构对阴极侧生成物水含量的影响不可忽略。     

PEMFC电极孔隙率的优化研究

对质子交换膜燃料电池单体建立了三维稳态电化学模型,考察了气体扩散层孔隙率对电池性能的影响,验证了扩散层孔隙率及层厚的变化反映从气体通道到扩散层和催化剂层的反应气体扩散量,进而影响电化学反应的活跃程度;以膜与阴极催化剂层界面处获得的最大电压为目标函数,采用鲍威尔搜索法对气体扩散层孔隙率进行数值优化,得到了扩散层孔隙率和层厚的最优值。通过优化前后氧气浓度和电流密度的对比显示,这些参数可以显著改善电极的传质性能,使燃料电池获得最佳性能。     

基于递归模糊神经网络的PEMFC温度控制研究

质子交换膜燃料电池(PEMFC)的工作温度对其发电性能和电池寿命具有重要影响,但由于PEMFC的非线性和时变特性,传统的控制策略较难获得很好的温度控制性能,以此推荐使用一种具有模糊推理、在线学习和动态映射能力的递归模糊神经网络控制器(RFNNC),将PEMFC工作温度有效控制在允许范围内.基于能量守恒定律建立PEM-FC的动态热模型,采用误差反传技术对该控制器参数进行自适应调整.仿真实验显示,RFNNC仅需35 s达到稳态,波动较小,比较RFNNC与PI控制和模糊控制的控制结果表明,推荐使用的RFNNC具有较好的温度跟踪性能.     

不同流场结构对PEMFC性能影响的模拟研究

该文模拟常规矩形平行流场、正六边形平行流场和正六边形蜂窝状仿生学流场对质子交换膜燃料电池（PEMFC）性能的影响。通过对极化曲线、氧气和水分布、膜电流密度以及压降和寄生功率密度进行分析,结果表明：正六边形流场表现出良好的输出性能,且正六边形蜂窝状流场的电流密度比常规矩形平行流场和正六边形平行流场分别提升11.28%和4.95%。此外,常规矩形平行流场、正六边形平行流场和正六边形蜂窝状流场的氧气不均匀度分别为0.64、0.53和0.41,正六边形蜂窝状流场展现出更好的水和膜电流密度分布能力,进一步说明正六边形流场缓解了氧气、水和膜电流密度分布不均匀的问题。正六边形蜂窝状流场压降虽比常规矩形平行流场和正六边形平行流场分别增加40.0%和27.7%,有较高的寄生功率密度,但仍获得了最大的净输出功率密度。     

温度、压力和湿度对质子交换膜燃料电池性能的影响

以Nafion质子交换膜燃料电池(PEMFC)为对象，通过测量电池的电流—电压、电流—功率和电压—时间曲线，研究了温度、压力和湿度等条件对电池性能的影响，同时也考察了电池的能量转换效率及短期运行时的稳定性，得出了电池较佳的工作条件。实验和计算结果表明：在反应温度为72℃、H2和02压力分别为0．2MPa、进气湿度饱和时，电池最大输出功率可达0．7W．cm^-2；在0．3W.cm^-2～0．7W．cm^-2范围内电池能量转换效率为62％—34％；在大电流密度下电池仍能稳定工作。     

不同衰退机理对PEMFC怠速工况性能衰退影响的模拟研究

分析质子交换膜燃料电池(PEMFC)怠速工况衰退机理,确定怠速工况不同衰退机理对燃料电池模型参数的影响,采用所建立的PEMFC二维等温多物理场模型,仿真研究燃料电池在怠速工况衰退前后的性能及各种衰退因素对电压衰减量的贡献和内部反应气体分布变化.研究结果表明,阴极活化损失增大是怠速工况下最重要的衰退因素,其次是开路电压衰...     

质子交换膜燃料电池（PEMFC）发动机循环水管理模型

首先测试了北京飞驰绿能电池技术有限公司设计制造的18kWPEMFC电堆,得到了输出电流、电压、反应气体流量,加温温度、电池堆上循环水入口和出口温度,以及电堆尺寸、质量等一系列参数,为了优化循环水管理,建立了循环水管理物理模型。该模型仅依赖于电堆输入和输出等宏观参数,不必考虑诸如质子交换膜的水迁移系数和冷却板,双极板上流场结构等微观参数。该模型在优化循环水系统配置,简化控制系统参数等方面具有一定优势。模型分析指出,在该发动机散热机制中,可以忽略热辐射以及反应物质流入流出对电池堆温度影响,循环水散热量占97%,18kWPEMFC发动机对散热器部分有较高要求,现阶段尚缺少燃料电池专用设备,采用中档轿车用散热器在经济和技术上都比较合适,为了达到快速启动目的PEMFC电动汽车必须配备功率较大的二次电池,二次电池功率依启动时间而定。     

基于神经元的PEMFC仿生流道性能模拟研究

质子交换膜燃料电池的流道结构对反应气体的流动和压降等具有重要影响。受神经元结构启发,提出一种兼顾径向流道和仿生流道在压降和气体分布均匀性优点的新型仿生流道结构。通过COMSOL软件模拟研究该新型流道的分支数（2~9）对质子交换膜燃料电池的性能曲线、阴极氧浓度分布、水浓度分布及压降的影响。结果表明：增加流道分支数可提高质子交换膜燃料电池的输出性能,其中9分支流道的峰值功率密度最大,为0.32 W/cm²,相比于2分支流道增加了的146.15%;分支数的增加也会提高氧浓度分布的均匀性,阴极气体扩散层与催化层交界面处的平均氧浓度从0.44 mol/m³提高到1.42 mol/m³,氧气不均匀度从2.13降低至0.90;分支数的增加也明显改善了弧形流道内的水浓度分布。此外,随着流道分支数从2增加到9,流道压降从38.57 Pa递减至4.47 Pa,质子交换膜燃料电池的输出功率从0.40 W递增到1.56 W。     

30KW质子交换膜燃料电池动力系统的研制

阐述30kW质子交换膜燃料电池（PEMFC）动力系统的研制工作;（1）建立30kW级的PEMFC测试站,达到对PEMFC控制运行以及对其性能进行测试改进的目的。（2）组装单电池并建立诊断,测试技术以及改进PEMFC膜电级（三合体）效能的技术;（3）组装5KW级,10kW级的PEMFC组功率模块,建立测试,改进其效能的技术;（4）将三台10KW级的PEMFC组功率模块进行系统集成完成30KW的PEMFC的动力系统。     

质子交换膜燃料电池自增湿研究进展

概述了质子交换膜燃料电池自增湿研究状况，指出自增湿的出发点是有效利用电池阴极过程生成水。综述了薄电解质膜、新型自增湿膜、自增湿流场结构三种方法的研究进展及适用空间。对自增湿技术发展前景进行了探讨。     

质子交换膜燃料电池阳极内流动与传质特性模拟

针对直流道质子交换膜燃料电池阳极，建立二维稳态的数学模型研究流道和电极内的流动和传质特性。模型采用通用Darcy定律来描述多孔介质与非多孔介质区域的流体流动，可以模拟沿流动方向上的物质变化情况，并探讨进口速度、进口氢气质量分数和催化层厚度对质量传输的影响。结果表明：增大进口速度、增加进口氢气质量分数、降低催化层厚度有利于氢气的质量传递。     

PEMFC分布式发电系统动态协调控制仿真

符号表m-质量/kg W-质量流量/kg·s-1N-电池个数I-电流/AM-摩尔分子质量F-法拉第常数/kg·mol-1/9.6 487×104C·mol-1R-气体常数/J·(mol·K)-1T-温度/KV-体积/m3A-反应面积/m2nd-电渗透系数Dw-扩散系数/m2·s-1cwa、cwc-膜阳极侧和阴极tm-膜厚度/m侧的水浓度/mol·m-2kp-水力     

Identification of the Hammerstein model of a PEMFC stack based on least squares support vector machines

This paper reports a Hammerstein modeling study of a proton exchange membrane fuel cell (PEMFC) stack using least squares support vector machines (LS-SVM). PEMFC is a complex nonlinear, multi-input and multi-output (MIMO) system that is hard to model by traditional methodologies. Due to the generalization performance of LS-SVM being independent of the dimensionality of the input data and the particularly simple structure of the Hammerstein model, a MIMO SVM-ARX (linear autoregression model with exogenous input) Hammerstein model is used to represent the PEMFC stack in this paper. The linear model parameters and the static nonlinearity can be obtained simultaneously by solving a set of linear equations followed by the singular value decomposition (SVD). The simulation tests demonstrate the obtained SVM-ARX Hammerstein model can efficiently approximate the dynamic behavior of a PEMFC stack. Furthermore, based on the proposed SVM-ARX Hammerstein model, valid control strategy studies such as predictive control, robust control can be developed.     

Effect of fluoride ions on corrosion behavior of SS316L in simulated proton exchange membrane fuel cell (PEMFC) cathode environments

In order to determine the suitability of SS316L as a bipolar plate material in proton exchange membrane fuel cells (PEMFCs), its corrosion behavior is studied under different simulated PEMFC cathode corrosion conditions. Solutions of 1 × 10⁻⁵ M H₂SO₄ with a wide range of different F⁻ concentrations at 70 °C bubbled with air are used to simulate the PEMFC cathode environment. Electrochemical methods, both potentiodynamic and potentiostatic, are employed to study the corrosion behavior. Scanning electron microscopy (SEM) is used to examine the surface morphology of the specimen after it is potentiostatic polarized under simulated PEMFC cathode environments. Auger electron spectroscopy (AES) analysis is used to identify the composition and the depth profile of the passive film formed on the SS316L surface after it is polarized in simulated PEMFC cathode environments. Photo-electrochemical (PEC) method and capacitance measurements are used to characterize the semiconductor passive films. The results of both the potentiodynamic and potentiostatic analyses show that corrosion currents increase with F⁻ concentrations. SEM examination results indicate that pitting occurs under all the conditions studied and pitting is more severe with higher F⁻ concentrations. From the results of AES analysis, PEC analysis and the capacitance measurements, it is determined that the passive film formed on SS316L is a bi-layer semiconductor, similar to a p-n heterojunction consisting of an external n-type iron oxide rich semiconductor layer (electrolyte side) and an internal p-type iron-chromium oxide semiconductor layer (metal side). Further analyses of the experimental results reveal the electronic structure of the passive film and shed light on the corrosion mechanisms of SS316L in the PEMFC cathode environment.     

Experimental investigation of self-regulating capability of open-cathode PEMFC under different fan working conditions

Self-regulation capability of the open-cathode PEMFC generally means that the stack itself can adjust its state to response to different operating conditions to achieve better performance when the external control strategy remains unchanged. In this paper, self-regulating capability of the stack are analyzed when its cooling fan works under blow or suction mode at different voltages. The result of output voltage shows that the stack achieves better self-regulation when the fan operates at 8.5 V in both blow mode and suction mode. Analysis of impedance spectra reveals that the stack can realize self-regulating function by adjusting activation resistance and ohmic resistance, and the cathode activation resistance is dominant. Furthermore, the result of a cycle load test indicates that the stack can better reflect the self-regulating capability in fan suction mode than in blow mode, and the stack can achieve better water and heat regulation in suction mode. Finally, according to the air velocity distribution and temperature change, it is found that self-regulating capability in suction mode play a better role due to more uniform heat remove. A suitable fan operating voltage and mode are critical for the self-regulating capability of the open-cathode PEMFC stack to maintain a water-heat balance.     

Effects of the humidity and the land ratio of channel and rib in the serpentine three‐dimensional PEMFC model

The construction of a reliable numerical model and the clarification of its operational conditions are necessary for maximizing fuel cell operation. Numerous operating factors, such as mole fractions of species, pressure distribution, overpotential, and inlet relative humidity, affect the performance of proton exchange membrane fuel cells (PEMFCs). Among these operational parameters, geometrical shape and relative humidity are investigated in this paper. Specifically, the land ratio of the gas channel and rib is an important parameter affecting PEMFC performance because current density distribution is influenced by this geometrical characteristic. Three main variables determine the current density distribution, namely, species concentration, pressure, and overpotential distributions. These distributions are considered simultaneously in assessing fuel cell performance with a given PEMFC cell‐operating voltage. In this paper, three different land ratio models are considered to obtain better PEMFC performance. Similarly, three different inlet relative humidity variations are studied to achieve an enhanced operating condition. A three‐dimensional numerical PEMFC model is developed to illustrate the current density distribution as the determining factor for PEMFC performance. Copyright © 2012 John Wiley & Sons, Ltd.     

Numerical simulation and experimental study on the effect of symmetric and asymmetric bionic flow channels on PEMFC performance under gravity

In proton exchange membrane fuel cell (PEMFC), bionic flow field design is to apply the biological characteristics of nature to the structure design of flow field. The flow field designed by bionics can improve the water balance of the fuel cell and make the fuel distribute uniformly in the flow field. In order to study the PEMFC performance of symmetric and asymmetric bionic flow channel under gravity, the simulation and visualization experiments are used to study the bionic flow channel in different orientations. Under the influence of gravity, the distribution characteristics of liquid water are changed in the flow channel, and the difference of the transport process of liquid water in two different bionic flow channel under gravity is obtained. The results of the simulation and visualization experiments show that the gravity has a significant effect on the transport process of liquid water in the bionic flow channel, and the water transport process in the two types of bionic flow channel is obviously different. Meanwhile, the performance of the fuel cells with two bionic flow channel at different orientations is tested by experiments. The results show that gravity has a significant effect on the performance of PEMFC with bionic flow field. And there are significant differences between symmetrical and asymmetric bionic flow channel on PEMFC performance. The results of I–V curve show that when the PEMFC with asymmetric bionic flow channel has the best performance in the orientation of perpendicularity.     

Simulation of FCV Fuel Consumption Using Stationary PEMFC

In the near future, the use of FCVs （fuel cell vehicles） is expected to help mitigate environmental problems such as exhaustion of fossil fuels and greenhouse gas emissions. Manufacturers publish an FCV＇s specific fuel consumption, but not its dynamic characteristics such as fuel consumption ratio and motor power ratio. Thus, it is difficult to reflect the dynamic characteristics of FCVs in lifecycle system evaluation. To solve this problem, we propose a fuel-consumption simulation method for FCVs using a 1.2 kW stationary PEMFC （proton exchange membrane fuel cell）. In this study, the specific fuel consumption under driving cycles such as the Japanese 10-15 and the JC08 modes are determined and compared with the FCV simulation results obtained using fuel consumption ratios derived from the stationary PEMFC. In the simulation, the specific fuel consumption was found to be 1.16 kg-H2/100-km for the base case under the Japanese 10-15 driving cycle.     

PEMFC碳纸气体扩散层内气液两相流格子Boltzmann模拟

为了提高质子交换膜燃料电池（PEMFC）水管理,本文借助多相流格子Boltzmann模型（LBM）模拟分析了PEMFC碳纸气体扩散层（GDL）内的气液两相输运过程,主要研究了GDL疏水性对气液两相流的影响。结果表明：液态水流路径不仅受到GDL结构形态的影响,而且受到材料疏水性影响。液态水在疏水性弱的GDL中不仅容易沁入,而且容易在孔隙中达到饱和;相反,在疏水性较强的GDL中,液态水很难突破沁入小尺寸孔隙,而从孔径较大的孔隙流通,从而形成毛细力主导的指进流动。