Current oscillations arising from nonlinear chemical dynamics in solid oxide fuel cells

Sands, Jonathan David (2015). Current oscillations arising from nonlinear chemical dynamics in solid oxide fuel cells. University of Birmingham. Ph.D.

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Abstract

Fuel cells are becoming increasingly important in the conversion of our society to clean, and renewable energy sources. However, there are some technical, as well as commercial barriers, which remain to be overcome before the fuel cell industry may be counted a success. One such problem is that of nonlinear current fluctuations, which have been observed under quite general conditions, in solid oxide fuel cells. This thesis attempts to elucidate the mechanisms driving this undesirable be- haviour, by developing a rational mathematical model based on fundamental chemical kinetics, and mass transfer effects, which take place within the porous anode of the fuel cell. A system of nonlinear, coupled ordinary differential equations is derived to describe the reaction and transfer processes associated with this fundamental model. This system is then rationally reduced to a planar dynamical system and the cases of weakly and fully humidified fuel streams are considered. Self-sustained, temporal oscillations are shown to arise through Hopf bifurcations in each case, and key parameter regimes leading to oscillatory behaviour are identified. Experiments have been conducted on commercial fuel cells, with results presented in Chapter 5.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):