Abstract
With increasing interest in clean energy generation in the transportation sector, increasing attention has been given to polymer-electrolyte-membrane fuel cells as viable power sources. One issue, the widespread application of this technology faces, is the insufficient knowledge regarding the transient behaviour of fuel cells, for instance, following a short-circuit event. In this paper, an agglomerate model is presented and validated, which enables the transient simulation of short-circuit events to predict the resulting peak current and discharge of the double layer capacity. The model allows for the incorporation of detailed morphological and compositional information regarding all fuel cell components. This information is used to calculate the reaction rate, diffusional and convectional species transfer, and the momentum transport. It can be shown that the charge in the double layer capacitance of the fuel cell is key to predicting the peak current and its charge is dependent on the operating conditions of the fuel cell. Further, the effects of the magnitude of the double layer capacity, current rise time and stoichiometry on the dynamic behaviour of the fuel cell are investigated. It can be shown that the discharge of the double layer capacity proceeds from the membrane through the catalyst layer to the gas diffusion layer and that the stoichiometry of the gas supply does not significantly change the absolute peak value of the short-circuit current.
Highlights
In an effort to reduce the emissions of climate gasses, all sectors of the energy system are incorporating larger fractions of renewable energies
In the GDL, the permeability κ is defined as a fixed value according to the value that is found in the datasheet [24]
The catalyst layer (CL) thickness zCL and the platinum to electrolyte ratio PtE have been identified as fitting variables, since neither is given in the datasheets of the used components
Summary
In an effort to reduce the emissions of climate gasses, all sectors of the energy system are incorporating larger fractions of renewable energies. All of this could help to reduce the cost of such a PEMFC powered system Storage devices, such as super-capacitors or batteries, are usually connected in parallel to fuel cell systems via DC/DC-converters in order to stabilise the grid voltage during load changes [5,6,7]. One aim of the following studies is to provide insight as to whether PEMFC current is sufficient for melting fuses or triggering the magnetic release of circuit breakers in the event of a short-circuit (SC) This potentially shortens the development time of new PEMFC systems and increases reliability, since state of the art protection devices can be used. This is a first step in the development of a model to simulate the behaviour of electrically controllable PEMFCs with integrated electric field modifier electrodes, as proposed in [20,21,22]
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