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Differences between theoretical and real operating conditions can occur during fuel cell operation, which can affect the fuel cell voltage. In the aging campaign studied in this work, an atypical behavior was observed on the voltage. The aim was then to understand if the voltage drop could have been caused by differences in operating conditions throughout the test campaign. To this end, a model expressing the voltage of a fuel cell cycling a mission profile for 2030h as a function of the related operating conditions was implemented. A voltage law was tested and improved by taking into account several different sets of operating conditions. A comparison of the coefficients associated with the parameters was also carried out. The results obtained with the model convinced us that the early voltage unusual behavior seen on the aging campaign was probably not related to the operating conditions. • This paper aims to develop a fuel cell stack voltage model based on an aging campaign depending on the operating conditions. • A voltage law was developed, tested and improved by taking into account several different sets of operating conditions. • The model accuracy depended on the chosen configuration, with a better prediction when all parameters were considered. • We concluded that the early life voltage fluctuations observed were not caused by differences in operating conditions. [ABSTRACT FROM AUTHOR]

In this work, three commercially available Membrane Electrode Assemblies (MEAs) from Advent Technology Inc. and Danish Power Systems, developed for a use in High Temperature Proton Exchange Membrane Fuel Cell (HT-PEMFC), were tested under various Operating Conditions (OCs): over-stoichiometry of hydrogen gas (1.05, 1.2, 1.35), over-stoichiometry of air gas (1.5, 2, 2.5), gas oxidant (O2 or air) and temperature (140 °C, 160 °C, 180 °C). For each set of operating conditions, a polarization curve (V–I curve) was performed. A semi-empirical and macroscopic (0D) model of the fuel cell voltage was established in steady state conditions in order to model some of these experimental data. The proposed parameterization approach for this model (called here the "multi-VI" approach) is based on the sensitivity to the operating conditions specific to each involved physicochemical phenomenon. According to this method, only one set of parameters is used in order to model all the experimental curves (optimization is performed simultaneously on all curves). A model depending on air over-stoichiometry was developed. The main objective is to validate a simple (0D) and fast-running model that considers the impact of air over-stoichiometry on cell voltage regarding all commercially available MEAs. The obtained results are satisfying with AdventPBI MEA and Danish Power Systems MEA: an average error less than 1.5% and a maximum error around 15% between modelled and measured voltages with only nine parameters to identify. However, the model was not as adapted to Advent TPS® MEA: average error and maximum error around 4% and 21%, respectively. Most of the obtained parameters appear consistent regardless of the OCs. The predictability of the model was also validated in the explored domain during the sensibility study with an interesting accuracy for 27 OCs after being trained on only nine curves. This is attractive for industrial application, since it reduces the number of experiments, hence the cost of model development, and is potentially applicable to all commercial HT-PEMFC MEAs. [ABSTRACT FROM AUTHOR]

In this work, a commercially available membrane electrode assembly from Advent Technology Inc., developed for use in high-temperature proton exchange membrane fuel cells, was tested under various operating conditions (OCs) according to a sensibility study with three OCs varying on three levels: hydrogen gas over-stoichiometry (1.05, 1.2, 1.35), air gas over-stoichiometry (1.5, 2, 2.5), and temperature (140 °C, 160 °C, 180 °C). A polarization curve (V-I curve) was performed for each set of operating conditions (27 V-I curves in total). A semi-empirical and macroscopic (0D) model of the cell voltage was developed in steady-state conditions to model these experimental data. With the proposed parameterization approach, only one set of parameters is used in order to model all the experimental curves (simultaneous optimization with 27 curves). Thus, an air over-stoichiometry-dependent model was developed. The obtained results are promising between 0.2 and 0.8 A·cm−2: an average error less than 1.5% and a maximum error around 7% between modeled and measured voltages with only 9 parameters to identify. The obtained parameters appear consistent, regardless of the OCs. The proposed approach with only one set of parameters seems to be an interesting way to converge towards the uniqueness of consistent parameters. [ABSTRACT FROM AUTHOR]

The operating conditions can have uncontrolled effects on the voltage of a High-Temperature Proton Exchange Membrane Fuel Cell (HT-PEMFC). For instance, the HT-PEMFC can be used at ambient pressure, i.e., without having a back pressure regulator. In this case, the variation in the atmospheric pressure directly affects pressures inside the fuel cell, which induces voltage variation. Moreover, in transient phases, several coupled phenomena can have an uncontrolled effect on the voltage. For example, following a change in the current operating point, thermal conditions in the fuel cell can vary, and the temperature stabilization then leads to a voltage variation. This article introduces a readjustment method for the fuel cell voltage to compensate for the effects of the pressure and temperature variations that are undergone and to decouple their effects. This methodology is based on the realization of a design of experiments to characterize the voltage sensitivity to pressure ([1; 1.5 bar]) and temperature ([120; 180 °C]) between 0.2 and 1 A/cm2 of an Advent PBI MEA (formerly BASF Celtec®-P 1100 W). The data obtained allowed identifying an empirical model that takes into account the aging caused by the experiment. Finally, the methodology is criticized before proposing an alternative method. [ABSTRACT FROM AUTHOR]