Daniela Chrenko

Abstract: The use of hydrocarbon fed fuel cell systems including a fuel processor can be an entry market for this emerging technology avoiding the problem of hydrogen infrastructure. This article presents a 1 kW low temperature PEM fuel cell system with fuel processor, the system is fueled by a mixture of methanol and water that is converted into hydrogen rich gas using a steam reformer. A complete system model including a fluidic fuel processor model containing evaporation, steam reformer, hydrogen filter, combustion, as well as a multi-domain fuel cell model is introduced. Experiments are performed with an IDATECH FCS1200™ fuel cell system. The results of modeling and experimentation show good results, namely with regard to fuel cell current and voltage as well as hydrogen production and pressure. The system is auto sufficient and shows an efficiency of 25.12%. The presented work is a step towards a complete system model, needed to develop a well adapted system control assuring optimized system efficiency.

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Abstract: This paper introduces a fuel cell system model based on Energetic Macroscopic Representation (EMR). EMR is a causal graphic modeling approach to describe complex multi domain systems, that facilitates inversion-based control structure development, called Maximum Control Structure (MCS). The EMR model is derived for a commercially available fuel cell system and corresponds well with experimental results. An inversion-based control is proposed for the air supply subsystem. The control corresponds well with the unknown internal control. The application of EMR and MCS marks a promising approach: control structure development based on experience is replaced by a systematic approach. This is especially meaningful for complex multi-domain systems like fuel cell systems.

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Abstract: This article introduces the energetic macroscopic representation (EMR) as approach for the dynamic modeling of a diesel fuel processing unit. The EMR is the ?rst step toward model based control structure development. EMR allows to divide the complex multi domain fuel processing with the modules: heat exchanger, reformer, desulfurization, water gas shift, preferential oxidation and condensation into simple sub blocks. Each sub block describes an elementary step of the fuel conversion, several of this blocks may occurre in a single module. Calculations are carried out through two basic principles: mass and energy balances. For model based control development, it is imperative that the model represents dynamic behavior, therefore temperature and pressure dynamics are taken into account. It is shown that the model is capable to predict the behavior of the entire fuel processing unit. The comparison between simulation results and given data leads to good accordance also with regard to temperature dynamics. Predictions regarding pressure dynamics are also provided.

Abstract: This paper introduces a fuel cell system model based on Energetic Macroscopic Representation (EMR). EMR is a causal graphic modeling approach to describe complex multi domain systems, that facilitates inversion-based control structure development, called Maximum Control Structure (MCS). The EMR model is derived for a commercially available fuel cell system and corresponds well with experimental results. An inversion-based control is proposed for the air supply subsystem. The control corresponds well with the unknown internal control. The application of EMR and MCS marks a promising approach: control structure development based on experience is replaced by a systematic approach. This is especially meaningful for complex multi-domain systems like fuel cell systems.

Abstract: In this paper, a polymer electrolyte fuel cell system is modeled in order to investigate the following operational modes: transient and nominal operations and rejuvenation process. As a preliminary investigation, the Ballard NEXA? power module performances are experimentally characterized. The power consumptions of ancillaries, such as the air fan, are then evaluated to investigate the system. To achieve an overall system model, components, such as the compressor, the pipes, the valves, the expander, and the humidi?er, are then simulated. This simulation is based on the same assumption: Fluidic circuits are described by an electrical analogy. The anodic gas management is ?nally described according to the delivered output current.

Abstract: In this paper, a polymer electrolyte fuel cell system is modeled in order to investigate the following operational modes: transient and nominal operations and rejuvenation process. As a preliminary investigation, the Ballard NEXA? power module performances are experimentally characterized. The power consumptions of ancillaries, such as the air fan, are then evaluated to investigate the system. To achieve an overall system model, components, such as the compressor, the pipes, the valves, the expander, and the humidi?er, are then simulated. This simulation is based on the same assumption: Fluidic circuits are described by an electrical analogy. The anodic gas management is ?nally described according to the delivered output current.

Abstract: RÉSUMÉ. Le transport routier est aujourd’hui au cœur d’enjeux sociétaux majeurs. Les réserves limitées d’hydrocarbures et la pollution croissante impliquent la recherche d’une alternative crédible au véhicule à moteur à combustion interne. Dans cette optique, l’utilisation des piles à combustible semble prometteuse. Néanmoins, les performances, intrinsèquement bonnes, d’un tel groupe électrogène sont grevées par une consommation énergétique importante des auxiliaires nécessaires à son propre fonctionnement. Une étape déterminante réside donc dans la mise au point de modèles de simulation de ce groupe électrogène multiphysique par excellence (car mettant en jeu des disciplines telles que l’électrochimie, l’électricité, la thermique, la thermodynamique, la mécanique des fluides, les matériaux) et multiéchelle (de temps et de taille). Ces modèles permettront alors d’augmenter le rendement énergétique de ce groupe électrogène, au travers de lois de commande locales et globales optimisées. Cet article s’intéresse à une approche de cette modélisation multiphysique basée sur la représentation énergétique macroscopique, ce formalisme visant à définir une représentation synthétique pour les systèmes complexes, respectant la dualité description structurelle/fonctionnelle, dans le cadre de la systémique (interactions) structuraliste (causalité intégrale). Un modèle de simulation en est déduit. ABSTRACT Fuel cell systems are very promising energy supply devices for both on-board and stationary applications. Nevertheless, their performances and efficiency, intrinsically far over those of internal combustion engines, are strongly diminished due to the high number of power-hungry ancillaries that are needed to operate the fuel cell stack itself. Thus, energy optimisation must be performed, through simulation, on the whole fuel cell system. Simulation models must also be proposed, taking into account all the phenomena taking place in such a multi-physical system. This paper proposes a global macroscopic modelling approach of a fuel cell system based on Energetic Macroscopic Representation.

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Abstract: This article presents the main aspects of the architecture of a fuel cell electric scooter. Based on a representative drive cycle the energy and power demand of such a vehicle are introduced and impacts of changes are discussed. Different possible energy and power sources like batteries, supercapacitors and fuel cell systems are introduced and characterized. Based on those system characteristics possibilities of a well adapted and available combination of energy sources is introduced. The power electronics needed for such a system are developed.

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Abstract: This document introduces the control structure development for the fuel processing unit of a pressurized, low temperature fuel cell system fed by commercial diesel. The control structure is developed using an inversion based method derived from the causal, graphic modeling approach called Energetic Macroscopic Representation. Its inversion leads to the maximum control structure. It has been applied to the fuel processing unit which transforms diesel into hydrogen rich gas. The approach contains mass ?ow and temperature control.

Abstract: This article introduces the Energetic Macroscopic Representation (EMR) as methodology to model a fuel cell. The causal, graphic modeling approach leads to the result that the fuel cell stack can be divided into seven different layers each one in?uencing on the stack voltage and the molar ?ow. The model obtained by this approach shows good agreement with measurement results.

Abstract: La Représentation Energétique Macroscopique (REM) est une méthodologie graphique pour développer une structure de commande pour des systèmes complexes, multi physiques. Grâce à l’approche REM, chaque système est synthétisable par des combinaisons de quatre éléments de base. A partir du modèle REM, une Structure Maximale de Commande (SMC) peut être déduite en appliquant des règles d?inversion systématiques. La SMC est une approche exhaustive de la commande, basée sur l’hypothèse que toutes les grandeurs sont mesurables. Le passage de la théorie à la pratique implique donc une simplification de la SMC : la Structure Pratique de Commande (SPC). La REM, développée dans des années 2000, s?est vue appliquée avec succès à différents domaines. Dans la présentation, les principaux concepts de la REM, de la SMC et de la SPC seront introduits par l’exemple. Enfin des applications de la REM à des systèmes énergétiques seront exposées. Ces travaux, menés au sein du laboratoire FEMTO-ST / FCLAB, concernent des dispositifs aussi variés que les batteries et les supercondensateurs ou les systèmes piles à combustibles.

Abstract: This paper describes the application of Energetic Macroscopic Representation (EMR) to model complex multi domain devices like fuel cell systems. The basic elements of EMR and its inversion - the Maximum Control Structure (MCS) - are given and the advantages of this tool to evaluate model based control are pointed out. Than the application of EMR on fuel cell systems is demonstrated. Furthermore the application of EMR and selected aspects of MCS on a commercially available fuel cell system is shown. The simulation results show that EMR is a valid tool to describe fuel cell systems.

Abstract: This paper introduces a fuel cell system model based on Energetic Macroscopic Representation (EMR). EMR is a causal graphic modeling approach to describe complex multi domain systems, that facilitates inversion-based control structure development, called Maximum Control Structure (MCS). The EMR model is derived for a commercially available fuel cell system and corresponds well with experimental results. An inversion-based control is proposed for the air supply subsystem. The control corresponds well with the unknown internal control. The application of EMR and MCS marks a promising approach: control structure development based on experience is replaced by a systematic approach. This is especially meaningful for complex multi-domain systems like fuel cell systems.

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