Numerical matching of anisotropic transport processes in porous electrodes of proton exchange membrane fuel cells Lei Xing a , Yuanxiang Xu a , Prodip K. Das b , Baodong Mao c , Qian Xu d , Huaneng Su d , Xu Wu e , Weidong Shi c,⇑ a Institute of Green Chemistry and Chemical Technology, Jiangsu University, Zhenjiang 212013, China b School of Engineering, Newcastle University, Newcastle NE1 7RU, UK c School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013, China d Institute of Energy Research, Jiangsu University, Zhenjiang 212013, China e School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China highlights  A two-phase flow, non-isothermal, CFD model for PEM fuel cells was developed.  Anisotropies of most important transport parameters were included and systematically studied.  Anisotropic properties increase model accuracy by agreeing better with experimental data.  Anisotropies of ion conductivity and gas diffusivity significantly affect cell performance. graphical abstract 0 5 10 15 20 80 100 0.5 V 0.2 V 0.8 V gas diffusivity thermal conductivity gas permeability water capillary diffusivity ion conductivity electron conductivity Sensitivity index of anisotripic variables article info Article history: Received 27 June 2018 Received in revised form 10 November 2018 Accepted 14 November 2018 Available online 15 November 2018 Keywords: PEM fuel cells Anisotropy Gas diffusion coefficient Capillary diffusion coefficient Electrode conductivity Thermal conductivity abstract Owing to the spatial orientations of carbon fibers, the porous electrodes of proton exchange membrane (PEM) fuel cells exhibit strong structural anisotropy, which affects the transport of species, ions, elec- trons, liquid water, and heat along the in-plane and through-plane directions. To capture the anisotropies of species transport, charge migration, and heat transport for PEM fuel cells operated at various loads, a two-phase flow, non-isothermal, computational fluid dynamics (CFD) model was developed and experi- mentally validated. Various anisotropic parameters were separately studied, and their contributions to the overall cell performance at different loads were compared. The results indicated the significance of anisotropic transport processes inside the electrodes, as the isotropic electrode properties overpredicted the cell performance. Among all the studied parameters, the anisotropies of the ion conductivity and gas diffusivity deserve careful consideration due to their significant impact on the cell performance, espe- cially at high current densities. The anisotropies of the electrode permeability for gas transport and ther- mal conductivity can be neglected because of their limited effects on the cell performance. The anisotropy of the electrode permeability for liquid-water transport under a capillary mechanism had a considerable influence on the cell performance owing to its impact on the water saturation within the electrode. Ó 2018 Elsevier Ltd. All rights reserved. 1. Introduction Proton exchange membrane (PEM) fuel cells are promising alternatives and complements to existing energy-conversion tech- nologies and have attracted intensive attention in the past decades https://doi.org/10.1016/j.ces.2018.11.034 0009-2509/Ó 2018 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: swd1978@ujs.edu.cn (W. Shi). Chemical Engineering Science 195 (2019) 127–140 Contents lists available at ScienceDirect Chemical Engineering Science journal homepage: www.elsevier.com/locate/ces