Current and voltage distributions in a tubular solid oxide fuel cell (SOFC)

Abstract

International audienceOne of the major obstacles to improving electrochemical performance of SOFCs is the limitation with respect to current collecting. The aim of this study is to examine these limitations on the basis of a model of a single cell of tubular SOFC. The simulation results allow us to understand and analyze the effects of ionic and electronic ohmic drops on cell performance. This paper describes a model using the CFD-Ace software package to simulate the behaviour of a tubular SOFC. Modelling is based on solving conservation equations of mass, momentum, energy, species and electric current by using a finite volume approach on 3D grids of arbitrary topology. The electrochemistry in the porous gas diffusion electrode is described using Butler-Volmer equations at the triple phase boundary. The electrode overpotential is computed at each spatial location within the catalyst layer by separately solving the electronic and ionic electric potential equations. The 3D presentation of the current densities and the electronic and ionic potentials allows analysis of the respective ohmic drops. The simulation results show that the principal limitations are at the cathodic side. The limitations due to ionic ohmic drops, classically considered to be the main restrictions, are confirmed. The particular interest of our study is that it also shows that, because of the cylindrical geometry, there is a significant electronic ohmic drop

Modelling effects of current distributions on performance of micro-tubular hollow fibre solid oxide fuel cells

“…8, as higher local current densities would cause higher heating due to the increased irreversible losses associated with the overpotentials, charged species flow and reaction entropies. Such temperature variations across the PEN of micro-tubular SOFCs have also been reported by other studies [20,33,57] with similar magnitudes of (10-15 K) temperature variations being reported across the PEN for similar lengths at similar polarisation [33]. Fig.…”

“…A finite volume 3-D model has been reported [20] of a tubular SOFC with inner diameter 5 mm and porous gas diffusion electrodes, in which spatially distributed current generation occurred. SOFC performance was predicted to increase with cathode conductivities, whereas low electronic conductivities caused strong potential gradients around the circumference of the cell when contact was made over a short arc.…”

SOFC fuelled by methane without coking: optimization of electrochemical performance

“…A quite good agreement between experimental and simulated data was obtained with these kinetic electrochemical parameters [22]. The velocity constants according to [7,13,14] are presented in the Table 3.…”

A novel bilayered Sr0.6La0.4TiO3/La0.8Sr0.2MnO3 interconnector for anode-supported tubular solid oxide fuel cell via slurry-brushing and co-sintering process

“…Solid oxide full cells (SOFC) represent an advanced technology for clean, high efficient and reliable energy conversion, which has attracted more and more attentions worldwide [1][2][3]. Tubular SOFC have many advantages such as the ease of sealing, the ability to endure the thermal stress caused by rapid heating [3][4][5][6].…”

“…Tubular SOFC have many advantages such as the ease of sealing, the ability to endure the thermal stress caused by rapid heating [3][4][5][6]. However, interconnector still remains to be a main challenge holding back single fuel cells from being compiled into stacks [7,8].…”