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液相进样直接甲醇燃料电池性能研究 总被引:6,自引:0,他引:6
报道了用研制的Pt-Ru/C催化剂, 采用特殊工艺制备了膜电极, 并组装了直接甲醇质子交换膜单电池系统。考察了电极扩散层制备方法、催化剂层中催化剂、Teflon-C以及Nafion液的用量等电极制备工艺条件以及空气作为氧化剂对单电池性能的影响。结果表明:采用刷涂法制备电极扩散层比喷涂法好,催化剂层中催化剂的优化含量为0.6mg·cm-2,Teflon-C、Nafion液的最佳用量分别为0.3 mg·cm-2、0.5 mg·cm-2。当工作温度为80℃时,输出电压为0.3V,氧气作为阴极气体的输出电流密度为36mA·cm-2;而空气作为阴极气体的输出电流密度为22.5mA·cm-2。膜电极有效面积为9cm2的的液相进样直接甲醇/氧气燃料电池三电池电堆的最大功率为0.285W,此时输出电压为0.7V,输出电流为0.407A;而液相进样直接甲醇/空气三电池电堆的输出电压为0.635V,输出电流为0.252A时,最大功率为0.160W。 相似文献
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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。 相似文献
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综述了质子交换膜在直接甲醇燃料电池中的作用和要求,目前质子交换膜的研究进展,重点介绍了适用于直接甲醇燃料电池用质子交换膜的各种材料的改性方法。按照物理和化学两种方法对几类质子交换膜材料进行改性。同时对比了改性前和改性后各种聚合物膜的物性特点。 相似文献
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根据已经建立的液体进料直接甲醇燃料电池一维模型讨论甲醇穿透对电池性能的影响.结果表明:电流密度较低时,甲醇穿透对电池性能的影响较大;随着电流密度增大,甲醇穿透对电池性能的影响越来越小. 相似文献
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Kah-Young Song 《Electrochimica acta》2007,53(2):637-643
The water crossover behavior in air-breathing direct methanol fuel cell (DMFC) was studied with varying structural variables of membrane electrode assembly (MEA), such as existence of microporous layer (MPL) in cathode diffusion layer, hydrophobicity of cathode backing layer, and membrane thickness. Water crossover from anode to cathode was lowered by the introduction of MPL to cathode backing layer, the reduction of hydrophobicity of cathode backing layer, and the reduction of membrane thickness. To account for the observed water crossover behavior, water back flow caused by the hydraulic pressure difference between the cathode and anode was considered. It was also found that the methanol crossover was lowered with the reduction of water crossover. The MEA designed for low water crossover revealed improved stability under continuous operation. 相似文献
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Optimization of the structure and texture of the cathode catalyst layer for air-breathing DMFC has been studied. Application of carbon nanotubes (CNT) as an additive to the cathode catalyst layer resulted in the increase of BET surface area and porosity of the catalyst layer due to filamentous morphology of CNT. Best performance was observed at the intermediate CNT/catalyst ratio of 0.05. I–U polarization and impedance analysis indicated that the faster oxygen reduction reaction at the open cathode is responsible for the power density improvement. Excessive cathode porosity was not favorable due to the decrease of the effective ionic conductivity of the catalyst layer. 相似文献
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针对单个乙醇溶液液滴在降压环境下蒸发的传热传质过程建立了数学模型。模型基于液相的能量守恒和 传质扩散理论,利用经典拓展模型计算液滴的质量蒸发率,并引入活度系数考虑液滴表面的蒸气分压。采用液 滴悬挂法进行实验,分别记录了乙醇溶液液滴和乙酸溶液液滴在降压蒸发过程中的液滴内温度变化。将实验数 据与计算结果对比,验证了模型的有效性。通过模型计算获得了液滴内部温度分布以及浓度分布随时间的变化。 结果表明:快速降压阶段空气流动较快,加之乙醇工质易挥发,液滴表面温度下降迅速,液滴内部温差和乙醇 浓度梯度较大;压力稳定后,空气流速为零,液滴内部温差和乙醇浓度梯度逐渐减小。由于液滴内部的热扩散 速率大于传质扩散系数,内部温度随时间的变化比浓度随时间的变化更快。 相似文献
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Effects of the sieve plate on hydrodynamics and mass transfer in an annulus sparged airlift reactor (0.08 m3, 1.3 m tall, and 0.284 m in diameter) were investigated. It is found that the sieve plate can significantly enhance gas holdup and volumetric mass transfer coefficient. The sieve pore plays an important role in breaking up bubbles. With a given free area ratio, the sieve plate with a larger sieve pore diameter is more efficient in increasing the volumetric mass transfer coefficient. Four different free area ratios between 37% and 73% are tested, and then an optimal free area ratio is determined. The effect of the sieve plate is found to be related to sparger types. The sieve plate leads to a larger increase of volumetric mass transfer coefficient with the O-ring distributor as compared to the 4-orifice nozzle. Empirical correlations and a hydrodynamic model are proposed to predict gas holdup, volumetric mass transfer coefficient and liquid velocity in airlift reactors with sieve plates. 相似文献
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The overall mass transfer coefficient kLa,F
in the flow characteristics was determined by the measurement of the diffusivity of ozone, density of aqueous solution, and
viscosity. However, the measured values kLa,F
in the range of 0.0096–0.0622 min-1 show large changes in hydraulic retention time, and the dissolved ozone concentration CL,F
presented under 0.1 mg/l is lower than the dissolved ozone observed. The overall mass transfer coefficient kLa,M in the ozone decomposition was determined by measurement of the equilibrium dissolved ozone, overall decomposition rate constant,
and overall Henry’s law constant. The measured values kLa,M
are in the range of 0.0441–0.0749 min-1, and they present small changes depending on the hydraulic retention time. Furthermore, the measured dissolved ozone concentration
CL,M presents a larger value than the CL,F. Then, the kLa,M is selected as an input overall mass transfer coefficient to predict the dissolved ozone requirement in the ozone contactor. 相似文献
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Seoung Hyun Kim Aneeta Bidkar Huu Hao Ngo Saravanamuthu Vigneswaran Hee Moon 《Korean Journal of Chemical Engineering》2001,18(2):163-169
Removal of a synthetic organic herbicide, metsulfuron-methyl (MSM), from aqueous solutions has been studied in batch and stirred
tank adsorbers charged with granular activated carbon particles. Two kinetic parameters, film mass transfer and intraparticle
diffusion coefficients, were estimated from concentration decay curves obtained in the batch adsorber. Based on these kinetic
parameters, the concentration profiles measured in the stirred tank adsorber were simulated. From experimental and simulated
results, it was proven that the film mass transfer at external surfaces of carbon particles controls the overall mass transfer,
particularly at low mixing (rotation of blades), during the adsorption of MSM by granular activated carbon particles. 相似文献
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微通道反应器能有效增强气液间传质,但处理能力受限。为了提高微通道的处理量,对微通道反应器的一维放大及气-液传质特性进行了研究。以乙醇胺(MEA)和甲基二乙醇胺(MDEA)混合水溶液吸收CO2为研究物系,在通道深度恒定时,考察了微通道宽度、气液流速对传质特性的影响。结果表明,传质系数和体积传质系数均随通道宽度先增大后缓慢减小,在通道宽度为1000 μm时达到最大值。比表面积随通道宽度的增大而降低。因此,合理增大微通道宽度,可在提高处理能力的同时,仍然保持良好的传质特性。 相似文献
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