Gefährdungsbetrachtung von PEM-Brennstoffzellen hinsichtlich des Einsatzes in explosionsgefährdeten Betriebsstätten (English shop)

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The aim of this work is the assessment of ignition hazards arising from a polymer electrolyte membrane fuel cell against the background of its use in operating sites subject to explosion hazards. The results of the evaluation of the hazard potential serve as a basis for the development of a possible explosion protection concept.

Taking into account the methodology of a risk assessment, a suitable procedure for an ignition hazard assessment of this innovative technology is first developed. Effective ignition sources and their causes are identified by means of an analytical, purely theoretical consideration. In doing so, the available information is included, taking possible fault conditions into account. The results of the hazard identification with regard to potential ignition sources are presented in the form of an event tree diagram. From this, the various causal chains that can lead to the occurrence of a potential ignition source for an explosive atmosphere surrounding the fuel cell become apparent.

The incorporation of the results of experimental tests on fuel cell test arrangements enables a qualitatively oriented estimation of the probability of occurrence of effective ignition sources. Various fault scenarios of the event tree diagram are reproduced in order to determine their criticality. In this context, the effects of an explosive combustion reaction within a fuel cell test arrangement, the ignitability of hydrogen/air mixtures during fuel cell operation, the ignition capability of internal ignition sources and the heating behaviour in the event of fuel gas crossover, short circuit and reactant starvation are investigated.

On the basis of the ignition hazard assessment, an explosion protection concept is developed which reduces the probability of occurrence of effective ignition sources to a sufficient extent.