Papers by Keyword: PEMFC

Abstract: The geometrical and flow parameters are governing the performance of the Proton Exchange Membrane Fuel Cell (PEMFC). The flow channels are used for distributing the reactants uniformly throughout the active area of fuel cell. Among different flow field designs, the serpentine flow field can give better performance to the PEM fuel cell. This paper numerically investigates the effects of the serpentine flow field with different number of passes. The 2 pass, 3 pass and 4 pass serpentine flow field designs of same rib size and channel size were modelled and analyzed using commercially available software package. From the polarization curves and performance curves drawn using the numerical results, the performance of three flow channel designs were compared and the maximum power densities of each design were found

Abstract: The internal humidity of vehicular proton exchange membrane strongly influences the performance of PEMFC, but it cannot be measured directly because of the special closed structure. Generally, the internal humidity is equivalent as the water content of the membrane. This paper studies the problem in humidity measurement. In the base of analysis about PEMFC water content mechanism, and by taking Fuzzy Sets as method, this paper builds a PEMFC humidity status monitor system model, which can monitor the humidity value and evaluate the FC system humidity status. The simulation results show that the model is working properly.

Abstract: For a distributed PEMFC power station utilizing biogas as a source to produce hydrogen, deep desulfurization of the biogas is important. ZnO/γ-Al₂O₃ and CuO/γ-Al₂O₃ were prepared by an impregnation method, and their performances on CH₃SH removal in the biogas have been studied. Results showed that CuO/γ-Al₂O₃ is able to remove CH₃SH to below 10 ppb at 250-400 °C and has a sulfur capacity of 0.056 mmol g^-1 at 300 °C. Regarding to the desulfurization mechanism, it has been confirmed that the removal of CH₃SH with CuO/γ-Al₂O₃ is based on chemical adsorption. In the desulfurization, CH₄s dry reforming took place at above 250 °C, and the generated H₂ and CO reduced CuO to Cu₂O and Cu. Further, it was supposed that H₂S generates through the hydrogenation of CH₃SH at the presence of H₂.

Abstract: An indirect fuel cell hybrid vehicle test bench is established for validating the control algorithm. The fuel cell output voltage is boosted through DC / DC converter. DC / DC converter positive and negative outputs are respectively connected with lithium battery sets positive and negative outputs. DC/DC converter output current and output power are regulated by the DC/DC converter main controller via CAN bus. So the fuel cell output power is regulated. Different fuel cell output power and motor input power proportional coefficient is adopted according to different lithium battery sets SOC (state of charge). The power distribution algorithm between fuel cell and Lithium battery sets is validated in tests.

Abstract: Fuel cells heat dissipation and cooling is a vital part of PEMFC heat management. This paper used pure water as the coolant to control the temperature distribution inside fuel cells. Established cooling channels geometrical model and simulated the temperature distribution in the steady state by using software SINDA/FLUINT. Then discusses the effects of cooling channels branch quantity, diameter and coolant velocity on fuel cell internal temperature distribution, concludes that multi-branch, large diameter pipes and low-velocity coolant make PEMFC work at best conditions.

Abstract: This paper deals with the decay of hydrogen-air proton exchange membrane fuel cell (PEMFC) stack, which has been used for three years, installing a 5kW fuel cell stack in a sightseeing bus to do the experiment, including road test and bench test. The results indicate that the hydrogen-air fuel cell stack power performance declines a lot, whose power conspicuously drops from 5kW to nearly 2.5kW, compared with that of a new one. There are many reasons of its decline, such as, proton membrane penetration and electrode destruction etc. It proves that the stack needs reasonable care and maintenance; otherwise, it tends to be easily exhaustive and thus greatly increases costs.

Abstract: Fuel cell water management has two conflicting requirements; too less water causing membrane dehydration and too much water causing liquid water flooding. Both phenomena resulting in significantly instability voltage performance because of imbalance water presence. Therefore, it is vital to analyze and understand the root cause of the problem hence a 96cm² transparent fuel cell was analyzed experimentally. The fuel cell allows clear visualization of flow channels, thus making it practical to analyze the transportation of reactants and products behavior. The experimental analyses were conducted under different reactant flow rate and inlet humidification variations. Highest cell performance was obtained under both reactant inlets humidification with largest air flow rates. On the other hand, when fuel and air in dry conditions, relatively lower cell voltage was obtained. Meanwhile, stable voltage was obtained under anode humidified and cathode non-humidified conditions with correct air to fuel ratio. Images of liquid water and voltage behavior are presented graphically corresponding to the changes in performance.

Abstract: Conjugated cis/trans isomer-based polymer membranes were prepared with 25 mol% of bis (4-hydroxyphenyl)-1,2-diphenylethylene (BHDPE). BHDPE has a conjugated nonplanar conformation structure containing the peripheral four aromatic rings which facilitate the formation of π-π interactions. A series of sulfonated poly (ethersulfone) s (SPBHDPE) was synthesized with concentrated sulfuric acid. The sulfonation took place selectively on the BHDPE unit, and simultaneously on the side-chain and main-chain phenyl groups. The SPBHDPEs consisted of a 4:6 ratio of cis and trans form mixtures. Composite membranes were prepared with copolymers and SiO₂ nanoparticles (20 nm, 4~10%wt). The composite membranes were cast from DMSO. A series of composite membranes structures and characteristic were evaluated by the ¹H-NMR spectroscopy, and thermal stabilities. The membranes were performed by ion exchange capacity (IEC), water uptake and proton conductivity.

Abstract: Epoxy/graphite powder (GP)/carbon fiber filament (CFF) composites have been prepared in various weight ratios and electrical and mechanical properties were estimated in order to use for the bipolar plate in PEMFC. As was expected, electrical conductivity increased with increasing total carbon content, and the value increased with increasing CFF content in the same carbon content. Tensile strength and flexural strength linearly decreased with increasing epoxy content, however in the same carbon content, these values increased with increasing CFF content. The good effect of CFF on the electrical and mechanical properties was due to the strong bonding between CFF and epoxy resin, which was confirmed by scanning electron microscopy (SEM).

Abstract: In Polymer Electrolyte Membrane Fuel Cell (PEMFC), bipolar plate is considered one of the most important components. Bipolar plate has a multi-functional in the fuel cell stack. The materials used in producing bipolar plate are greatly affecting its final properties. Through this study, the properties of bipolar plate composite will be observed. The based composition of this composite is 80% for multi-filler material and 20% binder material. Polypropylene (PP) will be used as binder material and for filler materials, Graphite (Gr) is the main filler and for the second filler materials its will vary with the usage of Carbon Black (CB), Iron (Fe), and Aluminum (Al) powder. The formation of this composite is produced through compression molding. The effect of different filler material loading on the properties such as electrical conductivity, bulk density and shore hardness are observed. The result showed the increasing of electrical conductivity as the increased the CB and Fe loading. But for Al, the result showed the decreasing of electrical conductivity as the loading of Al has been increased. Meanwhile the usage of CB clearly shown an improvement in electrical conductivity and able to meet the DOE target properties for development of PEMFC bipolar plate.