Kshitiz Singh, Bill Diong, Diego Estrada, and Bao Q. Nguyen
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Fuel cells, methanol, dynamic response, equivalent circuit model,parameter estimation
Fuel cells are increasingly important sources of electrical power as they can reduce the world’s use of fossil fuels, leading to beneﬁts such as decreased greenhouse gas emissions and cleaner air. However, their dynamic responses are slower than that of typical electrical and electronic systems drawing power from them. Hence, it is important to properly characterize an equivalent circuit model of the fuel cell’s dynamic behaviour, for performing accurate analysis and optimal design of the power systems based on such sources. This paper describes a method of estimating the parameters of a
second-order equivalent circuit model, a ﬁrst-order model being less accurate, for the direct methanol fuel cell from measurements of its responses to step-changes in load at various temperatures, fuel ﬂow rates and fuel concentrations. Analysis of these parameter values, which provided excellent ﬁts of the test data, indicated that they are quite sensitive to temperature but relatively insensitive to fuel ﬂow rates – more so for load-oﬀ than for load-on responses – for the same fuel concentration. Furthermore, diﬀerent fuel concentrations resulted in greater variability of the parameter values during the
load-on responses as compared to the load-oﬀ ones.