Constructal PEM fuel cell stack design

Abstract This paper describes a structured procedure to optimize the internal structure (relative sizes, spacings), single cells thickness, and external shape (aspect ratios) of a polymer electrolyte membrane fuel cell (PEMFC) stack so that net power is maximized. The constructal design starts from the smallest (elemental) level of a fuel cell stack (the single PEMFC), which is modeled as a unidirectional flow system, proceeding to the pressure drops experienced in the headers and gas channels of the single cells in the stack. The polarization curve, total and net power, and efficiencies are obtained as functions of temperature, pressure, geometry and operating parameters. The optimization is subjected to fixed stack total volume. There are two levels of optimization: (i) the internal structure, which accounts for the relative thicknesses of two reaction and diffusion layers and the membrane space, together with the single cells thickness, and (ii) the external shape, which accounts for the external aspect ratios of the PEMFC stack. The flow components are distributed optimally through the available volume so that the PEMFC stack net power is maximized. Numerical results show that the optimized single cells internal structure and stack external shape are “robust” with respect to changes in stoichiometric ratios, membrane water content, and total stack volume. The optimized internal structure and single cells thickness, and the stack external shape are results of an optimal balance between electrical power output and pumping power required to supply fuel and oxidant to the fuel cell through the stack headers and single-cell gas channels. It is shown that the twice maximized stack net power increases monotonically with total volume raised to the power 3/4, similarly to metabolic rate and body size in animal design.

[1]  A. Bejan.  Convection Heat Transfer , 1984 .

[2]  Xianguo Li,et al.  Modelling of polymer electrolyte membrane fuel cell stacks based on a hydraulic network approach , 2004 .

[3]  A. Bejan.  Shape and Structure, from Engineering to Nature , 2000 .

[4]  A. A. Kulikovsky,et al.  Two‐Dimensional Simulation of Direct Methanol Fuel Cell. A New (Embedded) Type of Current Collector , 2000 .

[5]  Ralph E. White,et al.  Comprehensive Treatise of Electrochemistry , 1981 .

[6]  J. C. Amphlett,et al.  A model predicting transient responses of proton exchange membrane fuel cells , 1996 .

[7]  Ralph E. White,et al.  Methanol Fuel Cell Model: Anode , 1999 .

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

[9]  Minggao Ouyang,et al.  A model predicting performance of proton exchange membrane fuel cell stack thermal systems , 2004 .

[10]  Shimshon Gottesfeld,et al.  Determination of water diffusion coefficients in perfluorosulfonate ionomeric membranes , 1991 .

[11]  Fernando H. Garzon,et al.  Determination of Ionic and Electronic Resistivities in Carbon/Polyelectrolyte Fuel-Cell Composite Electrodes , 2002 .

[12]  Adrian Bejan,et al.  Thermodynamic optimization of internal structure in a fuel cell , 2004 .

[13]  W. Cheney,et al.  Numerical analysis: mathematics of scientific computing (2nd ed) , 1991 .

[14]  A. Bejan,et al.  Constructal flow structure for a PEM fuel cell , 2004 .

[15]  J. P. Hartnett,et al.  Advances in Heat Transfer , 2003 .

[16]  Karl V. Kordesch,et al.  Fuel cells and their applications , 1996 .

[17]  W. Kout,et al.  Bipolar plates for PEM fuel cells , 2003 .

[18]  K. Agbossou,et al.  Dynamic behavior of a PEM fuel cell stack for stationary applications , 2001 .

[19]  S. G. Choi,et al.  Development of 1 kW class polymer electrolyte membrane fuel cell power generation system , 2002 .

[20]  Frano Barbir,et al.  An Analytical Solution of a Half‐Cell Model for PEM Fuel Cells , 2000 .

[21]  M. Valentini,et al.  A Working Model of Polymer Electrolyte Fuel Cells Comparisons Between Theory and Experiments , 2002 .

[22]  S. Klein,et al.  Experimental evaluation of the dynamic behavior of an air-breathing fuel cell stack , 2001 .

[23]  N. Jenkins,et al.  Proton exchange membrane (PEM) fuel cell stack configuration using genetic algorithms , 2004 .

[24]  R. C. Weast.  CRC Handbook of Chemistry and Physics , 1973 .

[25]  Allen J. Bard,et al.  Electrochemical Methods: Fundamentals and Applications , 1980 .

[26]  W. He,et al.  Active gas management for PEM fuel cell stacks , 2004 .

[27]  C. Lim,et al.  Materials and processes for light weight and high power density PEM fuel cells , 2000 .

[28]  T. Nguyen,et al.  A liquid water management strategy for PEM fuel cell stacks , 2003 .

[29]  O. J. Murphy,et al.  Low-cost light weight high power density PEM fuel cell stack , 1998 .

[30]  P. Pickup,et al.  Ionic Conductivity of PEMFC Electrodes Effect of Nafion Loading , 2003 .

[31]  R. Shah.  Laminar Flow Forced convection in ducts , 1978 .

[32]  J. A. Wesselingh,et al.  EXPLORING THE MAXWELL-STEFAN DESCRIPTION OF ION-EXCHANGE , 1995 .

[33]  Ramana G. Reddy,et al.  Materials and design development for bipolar/end plates in fuel cells , 2004 .

[34]  J. O'm. Bockris,et al.  Electro-chemical science , 1972 .

[35]  R. Datta,et al.  Modeling of Conductive Transport in Proton-Exchange Membranes for Fuel Cells , 2000 .

[36]  Dimos Poulikakos,et al.  Tree network channels as fluid distributors constructing double-staircase polymer electrolyte fuel cells , 2004 .

[37]  Ralph E. White,et al.  Steady-state operation of a compressor for a proton exchange membrane fuel cell system , 2000 .

[38]  William L. Masterton,et al.  Chemistry : principles and reactions , 2005 .