直接甲醇燃料电池反应物浓度测量技术

直接甲醇燃料电池的阳极采用甲醇作为燃料,阴极采用纯氧或空气作为氧化剂,具有能量密度高、燃料储存方便、结构简单的优点,有望成为下一代小型电子设备的电源。反应物的浓度对直接甲醇燃料电池的性能、效率和燃料利用率等都有很大的影响,因此对燃料电池中反应物的浓度进行准确测量至关重要。本文综述了直接甲醇燃料电池中反应物浓度的测量方法,主要包括化学测量方法和物理测量方法,并对这些测量方法的优缺点、基本原理及适用范围进行了分析和评述。     

高温甲醇燃料电池热管理系统设计

针对某型号高温甲醇燃料电池单电池模块,以实现精确控温、快速启动为目的进行了燃料电池热管理系统的设计、制造和测试。应用Matlab/Simulink平台开发了一种拟合简化方程的控制系统算法及其仿真计算平台,并对所设计的控制算法进行了仿真计算;同时对燃料电池内外传热介质循环回路及冷却系统换热器进行了重新设计与样件试制。完成了热管理系统单电池模块运行试验,将实测数据与仿真计算结果进行了对比分析。试验结果表明,所设计热管理系统成功将电池预热时间缩短了678s,稳定工况下冷却介质温度误差保持在±2℃以内,达到了预定的设计要求。样件试制及测试结果验证了热管理系统设计的可行性、准确性及实用性,为今后高温甲醇燃料电池热管理系统设计优化提供了理论和实际参考。     

被动式微型直接甲醇燃料电池燃料供应技术进展

作为便携式电子设备下一代电源的可能选择之一,微型被动式直接甲醇燃料电池受到越来越多的关注.微型化及被动式的特点给电池反应物的供给带来了新的挑战.本文对近年来被动式燃料电池的各种供液方式,包括气态供料、直接浸泡阳极、二氧化碳驱动供液,利用毛细作用和表面张力等进行了综述,对其技术特点及前景做了分析与讨论.     

被动式直接甲醇燃料电池的性能影响因素研究

研究了制约被动式直接甲醇燃料电池(被动式DMFC)性能的因素。通过测定电池的极化曲线、功率密度曲线、长时间放电曲线等手段研究了被动式甲醇燃料电池在不同阴极供料方式、不同阳极供料方式、不同催化剂载量、不同电池温度等条件下的放电特性。测试结果表明:阴极氧气扩散速率较慢是导致被动式电池性能较低的一个主要因素,阴极采用主动进料时电池的性能相比被动式DMFC提高了23.5%,最大功率密度达到8.4mW?cm?2。而且阴极的水淹问题也制约了被动式DMFC的长时间放电性能。提高阴阳极的催化剂载量能显著提高电池的性能,阴阳极催化剂载量为4.0mg?cm?2时,最大功率密度达到11.4mW?cm?2。但是催化剂载量的提高会影响电池的长时间放电性能,特别是,提高阴极催化剂载量能显著提高电池的温度,所以能较大提升电池的性能。     

燃料电池内部温度接触式测试技术进展

温度分布是评估燃料电池性能的一个重要参数,获得燃料电池内部的温度分布对提高电池的性能、改进电池的结构以及电池的模拟有重要的指导意义.介绍了燃料电池温度分布的各种实验测试技术,对接触式温度测试技术在燃料电池内的应用进行了综述,分析并评述了各种测试方法的优缺点以及适用范围.     

直接甲醇燃料电池质子交换膜的发展现状

直接甲醇燃料电池(DMFC)是20世纪90年代兴起的第六代燃料电池,以其诸多的优点引起人们的广泛关注和研究。其中聚合物电解质膜是DMFC的关键技术,起着隔离阴阳极、质子传输、绝缘电子的作用。它的作用决定着DMFC的输出功率、电池效率、成本及应用前景。本文介绍了已商品化的全氟磺酸膜(Nafion膜)的结构及性能、以及替代膜的国内外发展现状,指出DMFC用膜的研究是21世纪能源研究的重点。     

直接式甲醇燃料电池的研究进展

本文介绍了直接式甲醇燃料电池研究进展的现状，综合论述了甲醇阳极催化剂的研究进展，支撑物固体聚合物电解质和氧化钨的作用，催化反应机理和催化剂中毒的原因。     

相变材料用于质子交换膜燃料电池的热管理

质子交换膜燃料电池（PEMFC）因能量转化率高且环境友好,成为新一代能源动力的选择。通过分析温度对PEMFC运行性能的重要影响说明对电池进行有效热管理的重要性,按照主动冷却和被动冷却的分类方式对目前PEMFC热管理的研究现状进行归纳和综述,着重介绍运用相变材料的电池热管理系统中材料的选择和强化传热的方法,并对该领域未来研究方向进行了展望。     

直接甲醇燃料电池阳极催化剂的制备

直接甲醇燃料电池（DMFC）阳极催化剂是DMFC的关键材料之一,其电化学活性的大小对燃料电池的输出性能及成本起着关键作用。不同催化剂的制备技术决定了催化剂电化学活性的高低。介绍了DMFC阳极催化剂的几种制备方法,并对这些方法进行了评述,对制备DMFC阳极催化剂具有很好的参考价值。     

石墨烯基直接甲醇燃料电池催化剂的制备

通过浸渍还原法以乙二醇为还原剂制备了石墨烯及石墨烯负载的铂催化剂(Pt/Graphene),通过XRD、SEM、Raman对材料进行了分析,通过电化学测试与Pt黑催化剂对比,试验数据表明:Pt/Graphene比Pt黑催化剂电化学活性面积提高了28%,对甲醇电催化氧化峰电流提高了52%,电化学活性面积和甲醇氧化反应的稳定性均有所提高。     

Radiative heat flux measurement uncertainty

As part of an effort to characterize the uncertainties associated with heat flux measurements in a fire environment, an uncertainty analysis example was performed using measurement data from a room corner surface products test that followed the guidelines of ISO 9705. Equations to model the heat transfer at the surface of a Schmidt‐Boelter (thermopile) type total heat flux gauge were selected for use to calculate the incident radiative flux from a total heat flux measurement. The effects of the heat flux measurement uncertainty sources were evaluated by conducting an uncertainty propagation on the resulting equation for incident radiation. For the model equations and the example conditions selected, the free‐stream temperature estimate and the heat flux gauge calibration constant were determined to be major uncertainty contributors. The study demonstrates how to systematically identify major sources of uncertainty for the purpose of reducing total uncertainty and thereby enhancing experiment design. Published in 2003 John Wiley & Sons, Ltd.     

Effect of anode backing layer on the cell performance of a direct methanol fuel cell

We investigated experimentally the effect of the anode backing layers consisting of carbon papers with different thicknesses and different polytetrafluoroethylene (PTFE) contents on the cell performance of a direct methanol fuel cell (DMFC). The membrane electrode assemblies were prepared using the decal method such that the effect of different anode backing layers could be studied with the same anode catalyst layer, the same membrane and the same cathode. We found that a too thin anode backing layer resulted in lower cell voltages in the entire current density region, whereas a too thick backing layer led to a lower limiting current density. The reduced cell performance as a result of thinning the backing layer may be attributed mainly to the increased under-rib mass transport polarization as a result of weaker under-rib convection in a thinner backing layer. The experimental results also showed that the use of a PTFE-treated backing layer resulted in a lower limiting current density, attributing primarily to the increased mass transfer resistance as a result of the PTFE treatment.     

直接甲醇燃料电池阴极水的传输特性

利用COMSOL Multiphysics软件对直接甲醇燃料电池（DMFC）阴极模型进行计算,获得压力、速度、水、氧气和液态饱和度分布情况,研究扩散层在不同物理参数（如厚度、孔隙率、孔径大小和亲憎水性）下电池阴极水和氧气的传输情况,进一步建立扩散层孔隙率梯度的数学模型,研究扩散层孔隙率梯度以及支撑层参数对直接甲醇燃料电池性能和物质传输的影响。结果表明,扩散层具有大孔隙率、薄扩散层时均有利于氧气传质,可以使电池性能提高;扩散层孔隙率梯度的存在可以减轻氧气传输阻力,提高电池性能。     

Performance of a direct methanol fuel cell

The performance of a direct methanol fuel cell based on a Nafion® solid polymer electrolyte membrane (SPE) is reported. The fuel cell utilizes a vaporized aqueous methanol fuel at a porous Pt–Ru–carbon catalyst anode. The effect of oxygen pressure, methanol/water vapour temperature and methanol concentration on the cell voltage and power output is described. A problem with the operation of the fuel cell with Nafion® proton conducting membranes is that of methanol crossover from the anode to the cathode through the polymer membrane. This causes a mixed potential at the cathode, can result in cathode flooding and represents a loss in fuel efficiency. To evaluate cell performance mathematical models are developed to predict the cell voltage, current density response of the fuel cell.     

Development and operation of a 150 W air-feed direct methanol fuel cell stack

A five-cell 150 W air-feed direct methanol fuel cell (DMFC) stack was demonstrated. The DMFC cells employed Nafion 117^® as a solid polymer electrolyte membrane and high surface area carbon supported Pt-Ru and Pt catalysts for methanol electrooxidation and oxygen reduction, respectively. Stainless steel-based stack housing and bipolar plates were utilized. Electrodes with a 225 cm² geometrical area were manufactured by a doctor-blade technique. An average power density of about 140 mW cm^–2 was obtained at 110 °C in the presence of 1 M methanol and 3 atm air feed. A small area graphite single cell (5 cm²) based on the same membrane electrode assembly (MEA) gave a power density of 180 mW cm^–2 under similar operating conditions. This difference is ascribed to the larger internal resistance of the stack and to non-homogeneous reactant distribution. A small loss of performance was observed at high current densities after one month of discontinuous stack operation.     

燃料电池用碱性膜材料的研究进展

碱性膜直接甲醇燃料电池因为结合了质子交换膜燃料电池和液体碱燃料电池的优点而产生自身独特的性质,使其可以在一定程度上弥补质子交换膜燃料电池以及液体碱燃料电池的缺点而尤其引人关注。其中碱性膜电解质为碱性膜燃料电池的核心组件,其性能直接关系到燃料电池的性能及寿命。截至目前,关于碱性膜材料的制备及应用方面的报道较多,涉及的碱性膜电解质的种类也较多。本文以燃料电池用碱性膜电解质为综述内容,对国内外关于碱性膜电解质的研究报道进行系统的梳理和介绍。     

Systematic analysis of the direct methanol fuel cell

The dynamic operating behaviour of the direct methanol fuel cell (DMFC) is governed by several physico-chemical phenomena which occur simultaneously: double layer charging, electrode kinetics, mass transport inside the porous structures, reactant distributions in the anode and cathode flowbeds etc. Therefore it is essential to analyse the interactions of these phenomena in order to fully understand the DMFC. These phenomena were initially analysed independently by systematic experiments and model formulations. Electrode kinetics were determined by fitting models of varying complexity to electrochemical impedance spectroscopy (EIS) measurements. Reaction intermediates adsorbed on the catalyst seem to play a key role here. To describe mass transport across the DMFC a one-dimensional model was formulated applying the generalised Maxwell–Stefan equations for multi-component mass transport and a Flory–Huggins model for the activities of mobile species inside the membrane (PEM). Also swelling of the PEM as well as heat production and transport were considered. Finally, the anode flowbed was analysed by observing flow patterns in different flowbed designs and measuring residence time distributions (RTDs). Detailed CFD models as well as simpler CSTR network representations were used to compare to the experimental results. Even the simpler models showed good agreement with the experiments. After these investigations the results were combined: the electrode kinetics model was implemented in the mass transport model as well as in the CSTR network flowbed model. In both cases, good agreement, even to dynamic experiments, was obtained.