1. Numerical Analysis of Critical Performance Parameters of the Sulzer Hexis Fuel Cell Stack Pascal Held, Thomas Hocker CCP – Center for Computational Physics ZHW – University of Applied Sciences Winterthur Winterthur, Switzerland Jeannette Frei, Jan Hoffmann Sulzer Hexis Ltd. Winterthur, Switzerland

2. Fuel Cells - Science and Technology 2004 Introduction - Simulation - Software validation - Experimental setup - Hardware development - Program support - GUI development The Project is supported by the Swiss Commission for Technology and Innovation (KTI) 1998 the CCP starts with SOFC simulation Goal: support of the HEXIS SOFC development with “virtual experiments” Partners:

3. Fuel Cells - Science and Technology 2004 Contents Environment Volume Averaging Method Model Sensitivity Analysis Results

4. Fuel Cells - Science and Technology 2004 Hexis Fuel Cell System System HXS 1000 Premiere Stack Fuel Air after burning zone electrolyte (YSZ- ceramic) Current collector (MIC) Cell

5. Fuel Cells - Science and Technology 2004 Volume Averaging Method Effective Parameters

6. Fuel Cells - Science and Technology 2004 Vertical Temperature Gradient

7. Fuel Cells - Science and Technology 2004 Horizontal Temperatur Gradient

8. Fuel Cells - Science and Technology 2004 VAM Applied to SOFC Repetitive MIC-Element MIC-Structure k eff eff  eff  eff (T,j q,x H2,...) Effective Parameters Simulation of Transport Phenomena Reduced Geometric Complexity Less computational effort 2D Effective Model:

9. Fuel Cells - Science and Technology 2004 Input: Incorporation in 2D-Model Nubs/element - Sigma - Kappa - Permeability - Diffusion - Database: multi.sfc MIC - Gas Properties - Database: reaction.sfc Reaction prop. - el. Cond. Reaction th. Cond. z-direction th. Cond. x-direction Perm Diffusion nubs Diffusion Output: effective Parameters for 2D-Model Solving 3D with details Comparing 3D with and without details

10. Fuel Cells - Science and Technology 2004 Parameter Variation Original DirectHole Different MIC-Designs Contact Resistance Manganite R Cont,Cath Nubs MIC

11. Fuel Cells - Science and Technology 2004 Sensitivity Analysis Definition: Investigation into how projected performance varies along with changes in the key assumptions on which the projections are based. Goals: Identify parameters of major importance to a)find out if more accurate measurements required b)concentrate on parameters with optimization potential

12. Fuel Cells - Science and Technology 2004 Procedure Define upper and lower boundaries for input parameters (input parameters: material properties, geometries, operation condition) Evaluate output variables for all possible combinations of input parameters Statistical analysis of output variables

13. Fuel Cells - Science and Technology 2004 Input Variables Example: Free Volume in Anode/Cathode (Diff_x) Ion conductivity of Electrolyte (SigmaTKx) Contact Resistance (Contact_x) DesignEase Screenshot

14. Fuel Cells - Science and Technology 2004 Required Simulations DesignEase Screenshot Follows 2 n -law

15. Fuel Cells - Science and Technology 2004 Output Variables According to optimization goals For example: Area specific resistance (ASR) Temperature

16. Fuel Cells - Science and Technology 2004 Results Parameter F (contact resistance cathode) has a major impact on overall performance

17. Fuel Cells - Science and Technology 2004 Further Information CCP-ZHWhttp://www.ccp.zhwin.ch Sulzer HEXIS Ltd.http://www.hexis.ch NM GmbHhttp://www.nmtec.ch NMSesesNMSeses (public domain version) with reduced capabilities is available under http://www.nmtec.ch