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Pore-Scale Simulation of Cathode Catalyst Layers in Proton Exchange Membrane Fuel Cells (PEMFCs)

ZHENG, WEIBO
http://orcid.org/0000-0001-8206-2560
http://rave.ohiolink.edu/etdc/view?acc_num=osu1555436163992345

Abstract Details

2019, Doctor of Philosophy, Ohio State University, Mechanical Engineering.
Understanding the complex phenomena occurring inside the catalyst layer of a proton exchange membrane fuel cell (PEMFC) is critical to design of an optimized structure with low platinum loading and high performance. Describing detailed physical and chemical processes in the catalyst layer at the resolution of pore scale, pore-scale simulation is considered as a promising approach for use in understanding the structure-performance relation and subsequent optimization of the catalyst layer. For wide spread use in industry, the computational cost of pore-scale simulation needs to be reduced. To achieve this goal, a multiscale decomposition method that accelerates the convergence of an iteratively-solved variable distribution in porous electrodes is proposed. The multiscale method combines the macroscopic method with pore-scale simulation by decomposing a variable distribution into the macroscopic component and local fluctuations. The decomposition removes the slowly converged, long wavelength components in an iteratively-solved variable distribution, thereby accelerating the convergence. In this research, to reduce the computational cost of multiphase pore-scale simulation, the multiscale method is applied to the electrolyte phase potential and oxygen concentration, both of which converge slowly and limit the overall computational efficiency. The results show that the multiscale method can substantially accelerate the convergence without sacrificing the accuracy. It is also found that the estimation of the effective transport property appearing in the volume-averaged part of the multiscale method influences the convergence rate of the multiscale method. With more accurate estimation of an effective transport property, the multiscale method is shown to work more effectively, especially for a thick porous electrode. Being an important parameter in the application to oxygen concentration, the effective oxygen diffusivity in pores is systematically investigated using pore-scale simulation, and empirical correlations for use in the multiscale method, as well as other macroscopic simulation methods, are obtained. The emphasis is placed on the importance of Knudsen diffusion in nanoscale pores in the catalyst layer. The results also highlight the importance of liquid water distribution on the effective diffusivity estimation and, therefore, on the computational efficiency of the multiscale method. With reduced computational cost, multiphase pore-scale simulation of a catalyst layer used in a laboratory experiment is successfully performed. The proposed multiscale decomposition method can be extended to pore-scale simulation for any porous electrodes.
Seung Hyun Kim, Dr. (Advisor)
Sandip Mazumder, Dr. (Committee Member)
Jung Hyun Kim, Dr. (Committee Member)
Marcello Canova, Dr. (Committee Member)
149 p.
Mechanical Engineering
multiscale method; proton exchange membrane fuel cell; catalyst layer; pore-scale simulation; multiphase flow; computational cost; effective transport property; lattice Boltzmann method; porous media

Recommended Citations

Citations

  • ZHENG, W. (2019). Pore-Scale Simulation of Cathode Catalyst Layers in Proton Exchange Membrane Fuel Cells (PEMFCs) [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555436163992345

    APA Style (7th edition)

  • ZHENG, WEIBO. Pore-Scale Simulation of Cathode Catalyst Layers in Proton Exchange Membrane Fuel Cells (PEMFCs). 2019. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1555436163992345.

    MLA Style (8th edition)

  • ZHENG, WEIBO. "Pore-Scale Simulation of Cathode Catalyst Layers in Proton Exchange Membrane Fuel Cells (PEMFCs)." Doctoral dissertation, Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555436163992345

    Chicago Manual of Style (17th edition)

osu1555436163992345
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This open access ETD is published by The Ohio State University and OhioLINK.