Model of Two-Phase Flow and Flooding Dynamics in Polymer Electrolyte Fuel Cells

A mathematical model for two-phase flow and flooding dynamics in polymer electrolyte fuel cells PEFCs has been developed based on recent experimental observations. This three-dimensional PEFC model consists of four submodels to account for two-phase phenomena, including a catalyst coverage model in the catalyst layer, a two-phase transport model in the gas diffusion layer GDL, a liquid coverage model at the GDL-channel interface, and a two-phase flow model in the gas channel GC .T he multiphase mixture M 2 model is employed to describe liquid water transport in the GDL while a mist flow model is used in the gas channel. An interfacial coverage model by liquid water at the GDL/GC interface is developed, for the first time, to account for water droplet emergence on the GDL surface. The inclusion of this interfacial model not only gives the present two-phase model a capability to predict the cathode flooding effect on cell performance, but also ultimately removes the inability of prior two-phase models to correctly capture effects of the gas velocity or stoichiometry on cell performance. Water management is a central issue in design and optimization of polymer electrolyte fuel cells PEFCs. There are two wellunderstood reasons: first, the proton conductivity of the electrolyte membrane depends strongly on hydration; second, the presence of excessive liquid water covers catalyst sites in the catalyst layer as well as blocks the oxygen transport in the gas diffusion layer GDL, resulting in substantial concentration polarization. Therefore, a delicate balance of water in the cell must be maintained to ensure proper operation. Because the oxygen reduction reaction ORR in the cathode catalyst layer produces water, prevention of liquid water flooding is especially crucial on the cathode side of the cell.

[1]  Chaoyang Wang,et al.  Three-dimensional analysis of transport and electrochemical reactions in polymer electrolyte fuel cells , 2004 .

[2]  S. Dutta,et al.  NUMERICAL PREDICTION OF TEMPERATURE DISTRIBUTION IN PEM FUEL CELLS , 2000 .

[3]  C. Hebling,et al.  Visualization of water buildup in the cathode of a transparent PEM fuel cell , 2003 .

[4]  Chao-Yang Wang,et al.  Large-scale simulation of polymer electrolyte fuel cells by parallel computing , 2004 .

[5]  E. C. Childs.  Dynamics of fluids in Porous Media , 1973 .

[6]  J. Weidner,et al.  Diffusion of water in Nafion 115 membranes , 2000 .

[7]  Ned Djilali,et al.  A 3D, Multiphase, Multicomponent Model of the Cathode and Anode of a PEM Fuel Cell , 2003 .

[8]  Chaoyang Wang,et al.  Two-Phase Modeling and Flooding Prediction of Polymer Electrolyte Fuel Cells , 2005 .

[9]  Chaoyang Wang,et al.  Visualization of Liquid Water Transport in a PEFC , 2004 .

[10]  Sandip Mazumder,et al.  Rigorous 3-D mathematical modeling of PEM fuel cells. II. Model predictions with liquid water transport , 2003 .

[11]  T. Springer,et al.  Polymer Electrolyte Fuel Cell Model , 1991 .

[12]  Chao-Yang Wang,et al.  Liquid Water Transport in Gas Diffusion Layer of Polymer Electrolyte Fuel Cells , 2004 .

[13]  T. Nguyen,et al.  Two-phase flow model of the cathode of PEM fuel cells using interdigitated flow fields , 2000 .

[14]  Chao-Yang Wang,et al.  Computational Fluid Dynamics Modeling of Proton Exchange Membrane Fuel Cells , 2000 .

[15]  Shimshon Gottesfeld,et al.  The Water Content Dependence of Electro-Osmotic Drag in Proton-Conducting Polymer Electrolytes , 1995 .

[16]  Carl Berger,et al.  Handbook of fuel cell technology , 1968 .

[17]  Z. H. Wang,et al.  Two-phase flow and transport in the air cathode of proton exchange membrane fuel cells , 2000 .

[18]  Chao-Yang Wang,et al.  Fundamental models for fuel cell engineering. , 2004, Chemical reviews.

[19]  Hyunchul Ju,et al.  A single-phase, non-isothermal model for PEM fuel cells , 2005 .

[20]  Chao-Yang Wang,et al.  Multiphase flow and heat transfer in porous media , 1997 .

[21]  Sadik Kakac,et al.  Two‐dimensional model for proton exchange membrane fuel cells , 1998 .

[22]  F. Büchi,et al.  Investigation of the Transversal Water Profile in Nafion Membranes in Polymer Electrolyte Fuel Cells , 2001 .

[23]  Chao-Yang Wang,et al.  A multiphase mixture model for multiphase, multicomponent transport in capillary porous media—I. Model development , 1996 .

[24]  Jin Hyun Nam,et al.  Effective diffusivity and water-saturation distribution in single- and two-layer PEMFC diffusion medium , 2003 .

[25]  Hongtan Liu,et al.  A two-phase flow and transport model for the cathode of PEM fuel cells , 2002 .

[26]  T. Nguyen,et al.  Multicomponent transport in porous electrodes of proton exchange membrane fuel cells using the interdigitated gas distributors , 1999 .

[27]  Trung Van Nguyen,et al.  A Two-Dimensional, Two-Phase, Multicomponent, Transient Model for the Cathode of a Proton Exchange Membrane Fuel Cell Using Conventional Gas Distributors , 2001 .

[28]  S. Dutta,et al.  Three-dimensional numerical simulation of straight channel PEM fuel cells , 2000 .

[29]  Chao-Yang Wang,et al.  Electron Transport in PEFCs , 2004 .

[30]  Ned Djilali,et al.  THREE-DIMENSIONAL COMPUTATIONAL ANALYSIS OF TRANSPORT PHENOMENA IN A PEM FUEL CELL , 2002 .