Networking Fuel Cell Stacks

using Wolfram's Modelling and Simulation Suite

Gunnar Preiß

Hamburg University of Technology (TUHH)
German Aerospace Center (DLR)

Outline

Introduction

Single-Stack Fuel Cell System

Multi-Stack Fuel Cell System

Summary & Outlook

Introduction

Background

The multifunctional system integration of electrochemical energy conversion and storage technology demonstrates high overall system efficiency as well as economic benefit.

Introduction

Applications

Possible uses of multifunctional fuel cell systems include aerospace, marine, stationary, and transport applications.

Introduction

Motivation

Arguments indicating the investigations of fuel cell systems comprising multiple stacks:

Availability/Cost

Reliability

Maintenance

Performance

However, there are also substantial reservations against multi-stack fuel cell systems:

Complexity/Cost

Reliability

Controllability

Maintenance

Single-Stack Fuel Cell System

Reference System: Modelling results concerning the single-stack fuel cell system are validated using an 80(Subscript[kW, el]) (low-temperature) polymer-electrolyte-membrane fuel cell module of (Hydrogenics^®) HyPM™ HD-series.

Characteristic Equation

Key characterisitcs of any fuel cell are covered by its polarization curve representing the electrochemical cell potential as a function of current density.

(Subscript[E, cell])(i)=(Subscript[E, nernst])((E^0),T)-((R*T)/(α*F))Log[((i+(Subscript[i, loss]))/(Subscript[i, 0]))]-i*(Subscript[R, ohm])-((R*T)/(n*F))Log[((Subscript[i, lim])/((Subscript[i, lim])-i))]

Single-Stack Fuel Cell System

Reference System: Modelling results concerning the single-stack fuel cell system are validated using an 80(Subscript[kW, el]) (low-temperature) polymer-electrolyte-membrane fuel cell module of (Hydrogenics^®) HyPM™ HD-series.

Parameter Identification

Built-in Wolfram Language symbols are used to find parameter values (e.g. FindFit) or even for symbolic regression to adjust polarization curves (e.g. FindFormula).

Single-Stack Fuel Cell System

Reference System: Modelling results concerning the single-stack fuel cell system are validated using an 80(Subscript[kW, el]) (low-temperature) polymer-electrolyte-membrane fuel cell module of (Hydrogenics^®) HyPM™ HD-series.

Dynamic Behaviour

Model function of polarization characteristics is turned into a dynamic fuel cell model using SystemModeler, using either direct equation input or drag and drop modeling.

Single-Stack Fuel Cell System

Reference System: Modelling results concerning the single-stack fuel cell system are validated using an 80(Subscript[kW, el]) (low-temperature) polymer-electrolyte-membrane fuel cell module of (Hydrogenics^®) HyPM™ HD-series.

Dynamic Behaviour

The transient response of fuel cell potential with respect to a current ramp is simulated using SystemModeler.

Single-Stack Fuel Cell System

Reference System: Modelling results concerning the single-stack fuel cell system are validated using an 80(Subscript[kW, el]) (low-temperature) polymer-electrolyte-membrane fuel cell module of (Hydrogenics^®) HyPM™ HD-series.

System Efficiency

The model equations are analyzed with respect to their behaviour using SystemModeler simulation center (and Mathematica tools).

Multi-Stack Fuel Cell System

Reference System: Modelling results concerning the multi-stack fuel cell system are validated using two 10 (Subscript[kW, el]) and two 30 (Subscript[kW, el]) (low-temperature) polymer-electrolyte-membrane fuel cell modules of (Hydrogenics^®) HyPM™ HD-series.

Load Sharing

An optimized load sharing between multiple stacks in a single fuel cell system demonstrates an increased efficiency compared to conventional parallel or series connection.

Multi-Stack Fuel Cell System

Reference System: Modelling results concerning the multi-stack fuel cell system are validated using two 10 (Subscript[kW, el]) and two 30 (Subscript[kW, el]) (low-temperature) polymer-electrolyte-membrane fuel cell modules of (Hydrogenics^®) HyPM™ HD-series.

Dynamic Behaviour (In Progress)

An optimized time lag in operating point tracking of individual fuel cell stacks might balance the power output of the complete fuel cell system.

Summary & Outlook

Summary

Multi-stack fuel cell systems show an increased efficiency, especially for low power output -> motivates detailed further investigations.

Wolfram Mathematica and SystemModeler are well-suited for first estimations as well as detailed modeling and simulation of electrochemical energy technology.

({{Mathematica, SystemModeler}, {Design of Experiments, Model Development}, {Parameter Identification, Simulation Environment}, {Model Analysis, Model Analysis}, {(Control Systems), (Physical Computing)}})

Summary & Outlook

Outlook

Fuel cell networks will be systematically analyzed in more detail using modeling and simulation (together with a reference testbench).

The influence of operation in network configuration on the internal behaviour of fuel cells shall be investigated (3d problem).

Different types of fuel cells shall be evaluated with respect to potential for network configurations.

Backup