Numerical simulations of non-stationary distributions of electrochemical potentials in SOFC

Abstract

Purpose The purpose of this study is to develop a simulation method to calculate non-stationary distributions of the chemical potential of oxygen in a solid oxide fuel cell (SOFC) under operation. Design/methodology/approach The initial-boundary value problem was appropriately formulated and the appropriate boundary conditions were implemented so that the problem of non-stationary behavior of SOFC can be solved in accordance with actual operational and typical experimental conditions. The dependencies of the material properties on the temperature and partial pressure of oxygen were also elaborately introduced to realize actual material responses. The capability of the proposed simulation method was demonstrated under arbitrary operating conditions. Findings The steady state calculated with the open circuit voltage condition was conformable with the analytical solution. In addition, the transient states of the spatial distributions of potentials and currents under the voltage- and current-controlled conditions were successfully differentiated, even though they eventually became the same steady state. Furthermore, the effects of dense materials assumed for interconnects and current collectors were found to not be influential. It is thus safe to conclude that the proposed method enables us to simulate any type of transient simulations regardless of controlling conditions. Practical implications Although only uniaxial models were tested in the numerical examples in this paper, the proposed method is applicable for arbitrary shapes of SOFC cells. Originality/value The value of this paper is that adequate numerical simulations by the proposed method properly captured the electrochemical transient transport phenomena in SOFC under various operational conditions, and that the applicability was confirmed by some numerical examples.

Modified Energy Efficiencies of Proton‐conducting SOFCs with Partial Conductions of Oxide‐ions and Holes

“…This analytical model is simple and has been applied to the analyzes of a wide variety of phenomenon of SOFCs with mixed ionic electronic conductors (MIECs), for example potential profile in electrolyte , current‐voltage characteristics , , leakage‐current , –, and energy efficiency , , . These reference works include recent researches , , , . In terms of the application of this model to SOFCs, oxide‐ion conducting electrolytes were mainly studied , , .…”

“…These reference works include recent researches , , , . In terms of the application of this model to SOFCs, oxide‐ion conducting electrolytes were mainly studied , , . Recently, applications to proton‐conducting electrolytes have been developed and reported , , .…”

High Temperature Solid Oxide Electrolysis – Technology and Modeling

“…Further the response to temperature changes in startup operation [251][252][253] and for changing operation points [51] are investigated. [51,254] also examines the influence of an operating voltage varying in time while [255] studies the time-dependent distribution of the chemical potential of oxygen through the cell.…”

In Situ Evaluation of the Influence of Interstitial Oxygen on the Elastic Modulus of La2NiO4

“…In particular, enhancing the mechanical stability of SOFCs is one of the crucial issues to be addressed [4,5]. During operation, SOFC components can be exposed to severe temperature and oxygen chemical potential (µ O ) gradients [6][7][8]. Such temperature and µ O gradients can generate immense stress in the components, leading to serious mechanical failures in SOFCs, e.g., cracks and delamination [9,10].…”