Development of Large-Scale and Quasi Multi-Physics Model for Whole Structure of the Typical Solid Oxide Fuel Cell Stacks

Although the performance and corresponding manufacturing technology of solid oxide fuel cells (SOFC) units have greatly improved and have met commercial requirements over the past decades, they are constructed such that they perform poorly and lack strong duration outputs. Therefore, achieving high performance and extending duration at a stack level are challenges faced by the development process. This paper develops a large-scale and multiphysics model for the complete structure of a typical 10-cell SOFC stack. It includes solid components, flow paths, and porous sections—solid ribs, interconnectors, anode support, anode function layer, electrolyte layer, cathode layer, air/fuel feed manifolds, feed header, rib channels, exhaust header and outlet manifolds. The multiphysics application includes momentum, mass, energy and quasi electrochemical transporting; and their mutual coupling processes within the stack. This new model can help us understand the working specifics of the large-scale stack, obtaining distribution details of static pressure, species fraction, and temperature gradient; further addressing optimization of structure and operation parameters. These details serve as guidelines for practical structural designs and parameters in real stack levels

Percolation Theory in Solid Oxide Fuel Cell Composite Electrodes with a Mixed Electronic and Ionic Conductor

Percolation theory is generalized to predict the effective properties of specific solid oxide fuel cell composite electrodes, which consist of a pure ion conducting material (e.g., YSZ or GDC) and a mixed electron and ion conducting material (e.g., LSCF, LSCM or CeO2). The investigated properties include the probabilities of an LSCF particle belonging to the electron and ion conducting paths, percolated three-phase-boundary electrochemical reaction sites, which are based on different assumptions, the exposed LSCF surface electrochemical reaction sites and the revised expressions for the inter-particle ionic conductivities among LSCF and YSZ materials. The effects of the microstructure parameters, such as the volume fraction of the LSCF material, the particle size distributions of both the LSCF and YSZ materials (i.e., the mean particle radii and the non-dimensional standard deviations, which represent the particle size distributions) and the porosity are studied. Finally, all of the calculated results are presented in non-dimensional forms to provide generality for practical application. Based on these results, the relevant properties can be easily evaluated, and the microstructure parameters and intrinsic properties of each material are specified

Flow distribution analyzing for the solid oxide fuel cell short stacks with rectangular and discrete cylindrical rib configurations

The commercial software Ansys is utilized to simulate and compare the fuel and air flow distribution characteristics within the specific 10-cell solid oxide fuel cell (SOFC) stacks with different rib configurations, such as the rectangular, discrete symmetric cylindrical and staggered cylindrical rib configurations, respectively. The stack flow uniformity index and the standard flow deviation index are used to properly represent the flow distribution qualities among the piled cell units at stack level and among the rib channels within each cell unit, respectively. Part of the result shows that for a 10-cell short stack, the influences of different rib configurations on the flow uniformity at stack level are negligible, which further approves that a short modular stack as 10-cells is a proper choice in establishing the large power supplied SOFC system. A typical 10-cell modular SOFC using the rectangular rib configuration to establish the fuel rib channels and using the discrete symmetric cylindrical rib configuration to construct the air rib channels is concluded to be proper designing in achieving a good stack performance, while carefully considers the produced current collecting, flow distribution over the electrode surface and the reaction species transporting within the composite electrode

TaFLRS, a novel mitogen-activated protein kinase in wheat defence responses

Plants respond to biotic and abiotic stresses through the activation and coordination of various signalling pathways. The activation often requires the phosphorylation of proteins. In this study, we have identified the wheat TaFLRS MAP kinase (Fusarium and Leaf Rust Sensitive) gene that was upregulated in a wheat EST (expressed sequence tag) array analysis following a wheat-leaf rust interactive challenge. Our results demonstrate that TaFLRS is transcriptionally upregulated in incompatible interactions involving wheat and leaf rust and Fusarium graminearum, suggesting that

H2S poisoning effect and ways to improve sulfur tolerance of nickel cermet anodes operating on carbonaceous fuels

For commercialization-oriented solid oxide fuel cells, the state-of-the-art nickel cermet anodes are still the preferable choice because of their several favorable features, such as high electrical conductivity, good thermo-mechano compatibility with other cell components, and favorable electrocatalytic activity for hydrogen oxidation. One big drawback of such anodes is their susceptibility to sulfur poisoning, which may cause catastrophic damage to cell performance even at ppm concentration level in fuel gas, while practical fuels usually contain a certain amount of sulfur impurity with concentration usually higher than ppm level. In an attempt to make them applicable for operation on practical carbonaceous fuels, materials/morphology/cell operation mode modification has been intensively tried to alleviate the sulfur poisoning problem. Herein, recent progress in understanding the sulfur poisoning effect on the performance of SOFCs with Ni-based cermet anodes operating on sulfur-containing methane and CO fuels, and related strategies for improving the sulfur tolerance were reviewed. The application status of SOFCs operating with sulfur-containing fuels was also referred. The purpose of this review is to provide some useful guidelines for further modifications of Ni-based cermet anodes with enhanced sulfur tolerance when operating on practical sulfur-containing carbonaceous fuels