Abstract
Limiting the degradation of solid oxide fuel cells is an important challenge for their widespread use and commercialization. The computational expense of long-term simulation of a full stack with conventional models is immense. In this study, we present a multiscale three-dimensional model of a degrading full stack of solid oxide cells, where we integrate degradation phenomena of nickel particle coarsening in the anode electrode, chromium poisoning of the cathode electrode, and oxidation of the interconnect into a multiscale model of the stack. This approach makes this type of simulation computationally feasible, and 38 thousand hours of the stack operation can be simulated in 1 h and 15 min on a high-end workstation. Hereby one can start to explore the optimum operating conditions for a range of parameters. The model is validated with experimental data from an 18-cell Jülich Mark-F stack experiment and predicts common trends reported in the literature for evolutions of the stack performance, degradation phenomena, and the related model variables. Moreover, it captures how different regimes in the full stack degrades at different rates and how the various degradation phenomena interact over time. The model is used to investigate the effects of galvanostatic and potentiostatic operation modes, operating conditions, and flow configurations on the long-term performance of the stack. Results demonstrate, as expected, that potentiostatic operation mode, moderate temperature, lower load current, and counter-flow configuration improve the long-term performance of the stack.
Highlights
Solid oxide fuel cell (SOFC) is a promising candidate for stationary power plants and mobile applications in constant operation due to its high efficiency and fuel flexibility
This study aims to show a route for investigating the long-term performance of the stack that can be simulated on a desktop workstation in a relatively short time while including the known degradation phenomena reported in the literature
Since this study aims to model the degradation phenomena over the lifetime of the stack, the governing equations in their transient forms indicated in Table 2 are sufficient
Summary
Solid oxide fuel cell (SOFC) is a promising candidate for stationary power plants and mobile applications in constant operation (e.g. larger ships) due to its high efficiency and fuel flexibility. Its market uptake is currently hindered by high costs stemming from its current low volume production, mechanical failures due to e.g. crack formation and creep, and degradation limiting its lifetime. The degradation could be induced mechanically [1] or chemically such as interconnect oxidation [2], carbon deposition [3], nickel particle coarsening [4], and the poisoning of the cathode and anode by chromium [5] and sulfur [6], respectively. The interplay of the degradation phenomena, i.e. their multiphysics nature, is a hurdle against developing a precise prediction for each degradation phenomenon [8]
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