Numerical Analysis of Critical Performance Parameters of the

Sulzer Hexis Fuel Cell Stack

Pascal Held, Thomas HockerCCP – Center for Computational Physics

ZHW – University of Applied Sciences WinterthurWinterthur, Switzerland

Jeannette Frei, Jan HoffmannSulzer Hexis Ltd.

Winterthur, Switzerland

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:

Fuel Cells - Science and Technology 2004

Contents

• Environment

• Volume Averaging Method

• Model

• Sensitivity Analysis

• Results

Fuel Cells - Science and Technology 2004

Hexis Fuel Cell SystemSystemHXS 1000 Premiere

Stack

Fuel

Airafter burning zone

electrolyte(YSZ-ceramic)

Current collector (MIC)

Cell

Fuel Cells - Science and Technology 2004

Volume Averaging Method

EffectiveParameters

Fuel Cells - Science and Technology 2004

Vertical Temperature Gradient

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Horizontal Temperatur Gradient

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VAM Applied to SOFC

RepetitiveMIC-Element

MIC-Structure

•keff

eff

eff

eff(T,jq,xH2,...)

Effective ParametersSimulation of Transport Phenomena

• Reduced Geometric Complexity• Less computational effort

2D Effective Model:

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

Diffusionnubs

Diffusion

Output:

effective Parameters

for 2D-Model

Solving3D withdetails

Comparing 3D with and without details

Fuel Cells - Science and Technology 2004

Parameter Variation

Original Direct Hole

Different MIC-Designs Contact Resistance

Manganite

RCont,Cath

Nubs MIC

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 toa) find out if more accurate measurements requiredb) concentrate on parameters with optimization potential

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

Fuel Cells - Science and Technology 2004

Input VariablesExample:• Free Volume in Anode/Cathode (Diff_x)• Ion conductivity of Electrolyte (SigmaTKx)• Contact Resistance (Contact_x)

DesignEase Screenshot

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Required Simulations

DesignEase Screenshot

Follows 2n-law

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Output Variables

• According to optimization goals

For example:• Area specific

resistance (ASR)• Temperature

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Results

Parameter F (contact resistance cathode) has a major impact on overall performance

Fuel Cells - Science and Technology 2004

Further Information

CCP-ZHW http://www.ccp.zhwin.ch

Sulzer HEXIS Ltd. http://www.hexis.ch

NM GmbH http://www.nmtec.ch

NMSeses NMSeses (public domain version) with reduced capabilities is available under http://www.nmtec.ch