Evaluation of Lattice Boltzmann Method for Reaction-Diffusion Process in a Porous SOFC Anode Microstructure

Author(s):  
Hedvig Paradis ◽  
Bengt Sundén

In the microscale structure of a porous electrode, the transport processes are among the least understood areas of SOFC. The purpose of this study is to evaluate the Lattice Boltzmann Method (LBM) for a porous microscopic media and investigate mass transfer processes with electrochemical reactions by LBM at a mesoscopic and microscopic level. Part of the anode structure of an SOFC for two components is evaluated qualitatively for two different geometry configurations of the porous media. The reaction-diffusion equation has been implemented in the particle distribution function used in LBM. The LBM code in this study is written in the programs MATLAB and Palabos. It has here been shown that LBM can be effectively used at a mesoscopic level ranging down to a microscopic level and proven to effectively take care of the interaction between the particles and the walls of the porous media. LBM can also handle the implementation of reaction rates where these can be locally specified or as a general source term. It is concluded that LBM can be valuable for evaluating the risk of local harming spots within the porous structure to reduce these interaction sites. In future studies, the information gained from the microscale modeling can be coupled to a macroscale CFD model and help in development of a smooth structure for interaction of the reforming reaction and the electrochemical reaction rates. This can in turn improve the cell performance.

2018 ◽  
Vol 22 (4) ◽  
pp. 1831-1843 ◽  
Author(s):  
Hou-Ping Dai ◽  
Zhou-Shun Zheng ◽  
Wei Tan

In this paper, a Riesz space fractional reaction-diffusion equation with non-linear source term is considered on a finite domain. This equation is commonly used to describe anomalous diffusion in thermal science. To solve the diffusion equation, a new fractional lattice Boltzmann method is proposed. Firstly, a difference approximation for the global spatial correlation of Riesz fractional derivative is derived by applying the numerical discretization technique, and a brief convergence analysis is presented. Then the global spatial correlation process is inserted into the evolution process of the standard lattice Boltzmann method. With combining Taylor expansion, Chapman-Enskog expansion and the multi-scales expansion, the governing evolution equation is recovered from the continuous Boltzmann equation. Three numerical examples are provided to confirm our theoretical analysis and illustrate the effectiveness of our method at last.


2017 ◽  
Vol 20 (10) ◽  
pp. 899-919 ◽  
Author(s):  
Sajjad Foroughi ◽  
Mohsen Masihi ◽  
Saeid Jamshidi ◽  
Mahmoud Reza Pishvaie

Author(s):  
Kyle N. Grew ◽  
Abhijit S. Joshi ◽  
Aldo A. Peracchio ◽  
Wilson K. S. Chiu

A coupled electrochemical reaction and diffusion model has been developed and verified for investigation of mass transport processes in Solid Oxide Fuel Cell (SOFC) anode triple-phase boundary (TPB) regions. The coupled model utilizes a two-dimensional (2D), multi-species Lattice Boltzmann Method (LBM) to model the diffusion process. The electrochemical model is coupled through localized flux boundary conditions and is a function of applied activation overpotential and the localized hydrogen and water mole fractions. This model is designed so that the effects of the anode microstructure within TPB regions can be examined in detail. Results are provided for the independent validation of the electrochemical and diffusion sub-models, as well as for the coupled model. An analysis on a single closed pore is completed and validated with a Fick's law solution. A competition between the electrochemical reaction rate and the rate of mass transfer is observed to be dependent on inlet hydrogen mole fraction. The developed model is presented such that future studies on SOFC anode microstructures can be completed.


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