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The successful and fast start-up of proton exchange membrane fuel cells (PEMFCs) at subfreezing temperatures (cold start) is very important for the use of PEMFCs as energy sources for automotive applications. The effective thermal management of PEMFCs is of major importance. When hydrogen is stored in hydride-forming intermetallics, significant amounts of heat are released due to the exothermic nature of the reaction. This excess of heat can potentially be used for PEMFC thermal management and to accelerate the cold start. In the current work, this possibility is extensively studied. Three hydride-forming intermetallics are introduced and their hydrogenation behavior is evaluated. In addition, five thermal management scenarios of the metal hydride beds are studied in order to enhance the kinetics of the hydrogenation. The optimum combination of the intermetallic, hydrogenation behavior, weight and complexity of the thermal management system was chosen for the study of thermal coupling with the PEMFCs. A 1D GT-SUITE model was built to stimulate the thermal coupling of a 100 kW fuel cell stack with the metal hydride. The results show that the use of the heat from the metal hydride system was able to reduce the cold start by up to 8.2%. [ABSTRACT FROM AUTHOR]

Abstract: A Pt/C electrocatalyst was prepared from colloidal Pt nanoparticles stabilised by Nafion. This electrocatalyst was found to exhibit negligible degradation under a potential cycling regime conducted on a model thin-film catalyst layer in a 3-electrode cell set-up, in which an E-Tek Pt/C commercial catalyst showed a 23% loss of specific electrochemical surface area (SECSA). The enhanced durability of the Nafion-derived is thought to arise from the protection of Pt particles against dissolution and sintering by the surrounding Nafion layer. The use of the ionomer phase as a protective agent in the catalyst layer presents a novel strategy for the production of more durable Pt/C catalysts for the Proton Exchange Membrane Fuel Cell (PEMFC), which currently presents a significant challenge for the commercialisation of this technology. [Copyright &y& Elsevier]

Overall fuel cell system efficiency must include consideration of the parasitic loads associated with operating the stack. For an air-cooled open-cathode polymer electrolyte fuel cell (PEFC) the air blowers form the largest parasitic load and have a direct influence of the performance of the stack and its temperature; increasing air flow often leading to improved performance at the expense of increasing parasitic load. Here, electro-thermal performance maps are used to characterise stack operation with varying air flow rate (for both cooling and cathode oxygen supply). The non-linear power requirement of air blowers is used to modify stack-level electro-thermal maps to give system-level performance maps capable of identifying the optimum air flow rate to maximise net power output and consequently efficiency at a given operating point. The electro-thermal map concept is invoked in the consideration of dynamics of fuel cell system operation with issues pertaining to speed of response, durability and system self-sustainable operation. [ABSTRACT FROM AUTHOR]