工程科技研究所暨機械工程系 副教授 蔡錦山 中華民國 100 年 4 月 13 日 指叉型質子交換膜燃料電池之參數研究 Parametric Study on the Performance of the PEMFC with Interdigitated Flow Fields 「南榮技術學院 99 學年度教師教學媒體觀摩及數位教材製作」

Introduction § Model description § Solution procedures § Conclusion § Outline Results and discussion §

Introduction Picture source : Z. Shi, X. Wang and Z. Zhang, “Comparison of 2D PEM Fuel Cell Modeling Using Comsol”, COMSOL User Conference 2006, OTC 23, 2006, BOSTONE.

PEMFC features Low emission Low noise and maintenance High power density Low operation temperature High efficiency

Model description simulation section rib inlet channel exhaust channel cathode bipolar plate membrane anode bipolar plate interdigitated flow field

COMSOL multiphysics Solution procedures results analysis and discussion results analysis and discussion results analysis and discussion results analysis and discussion assumptions solver geometry parameters boundary conductions mathematical model

Assumptions   Constant operating temperature and laminar flow   Ideal gas mixture   Constant viscosity and density   H 2 and H 2 O on the anode ； O 2, H 2 O and N 2 on the cathode   Electrodes and membrane are made of homogeneous porous materials

Model geometry anode GDL cathode GDL fuel +H 2 O membrane cathode current collector fuel +H 2 O air +H 2 O anode current collector

Mathematical model of PEMFC (1/2) Porous materials : in the membrane in the anode and cathode

Mathematical model of PEMFC (2/2) Current density in the anode and cathode :

Boundary conditions (1/3) Flow channel : at the inlet of the anode at the outlet of the anode at the inlet of the cathode at the outlet of the cathode

Boundary conditions (2/3) At the interface between the anode and membrane :

Boundary conditions (3/3) At the interface between the cathode and membrane :

Parameters

Solver Fuel cell modeling is multiphysics modeling COMSOL Multiphysics

Postprocessing COMSOL multiphysics Subdomain and boundary conditions settings Meshing Drawing Modeling Solver parameters and manager

Modeling

Drawing

Meshing

Subdomain settings

Boundary conditions settings

Solver parameters

Solver manager

Solve problem

Postprocessing (1/4)

Postprocessing (2/4) 匯出圖檔 匯出數值文字檔

Postprocessing (3/4)

Postprocessing (4/4)

Results and discussion Experimental data source: W. He, J. S. Yi and T. Nguyen, “Two-phase Flow Model of the Cathode of PEM Fuel Cell Using Interdigitated Flow Fields”, AIChE J., vol. 46(10), pp , Comparisons of experimental data with the present study : polarization curve Permeability S/m m m atm

Flow channel and rib width normal ionic current density

Conductivity of the membrane (b) polarization curve (c) power density (a) normal ionic current density

Conductivity of the bipolar plate (a) polarization curve(b) power density

Porosity (1/2) (a) polarization curve(b) power density

Porosity (2/2) (a) (b) (c) The reactant mass fractions in the anode (left) is hydrogen and that in the cathode (right) is oxygen.

Tortuosity (a) polarization curve(b) power density

Inlet pressure of the anode and cathode (a) polarization curve(b) power density

Operation temperature (a) polarization curve(b) power density

Electroosmotic drag (a) polarization curve(b) power density

Conclusions (1/2)   The simulation results show that the PEMFC with altered channel and rib width decreasing the size of both for fuel cell polarization curve was advantageous.   The hydrogen mass fraction in the anode increases and the oxygen mass fraction in the cathode decreases along the flow direction, respectively.

Conclusions (2/2)   Increasing the material conductivity and reactants pressure at the inlets, reducing the fuel cell operation temperature, and decreasing the tortuosity, electroosmotic drag coefficient of the porous media can improve the PEMFC performance.

Thanks for your attentions !