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Theses

Energetic Macroscopic Representation Modeling and Control of a Low Temperature Fuel Cell System Fed by Hydrocarbons

Abstract : Fuel cell systems (FCS) are considered to be upcoming technology for electrical power generation. They can be used for portable, stationary and transportation applications. Fuel cells are run on hydrogen. Hydrogen can be produced either by electrolysis using electricity from renewable energy or by converting conventional hydrocarbons into a hydrogen rich gas. Among others, a FCS incorporates two main components, the fuel processing unit and the fuel cell stack. The use of hydrocarbon fueled FCS as auxiliary power units (APU) in transportation applications is a possible entry market for this technology that utilizes the existing infrastructure of fuel supply.

Hydrocarbon fueled FCSs are complex multi-domain systems combining aspects from various energetic regimes, like electro-chemical, electrical, pneumatical and thermal. These systems work only in a narrow and well defined range of operation. Therefore, this application requires a well adapted system control to respect these constraints. Classical control structure development often requires the transfer function of the system. This can be difficult or even impossible to derive for complex systems. Therefore, control structure development for complex multi-domain systems is often based on empirical observation and experience. It is desireable to find an approach that allows the development of a control structure based on system description. Such an approach will simplify control structure development and ensure that the control structure is adapted to the system needs. Model based control structure design is an approach that can meet these demands.

This thesis presents a complete model of a low temperature FCS fueled by commercial diesel, and is well adapted for model based control development. The studied FCS provides 25kW electric power, and at the same time the system waste heat is used for climatization.
In chapter 2 several modeling methodologies are introduced. Each is evaluated to see if it can be used to model a complex multi-domain system and if it can be used for model based control structure development. Energetic Macroscopic Representation (EMR) is identified as the best adapted methodology and is applied to chemical reactions and mass transfer.
In chapter 3 a model of the fuel processor is presented and implemented in Matlab/Simulink\texttrademark. To obtain a hydrogen rich gas, the supplied hydrocarbon has to be broken up. Subsequently, the gas has to be purified in order to avoid contamination of the fuel cell with sulfur and carbon monoxide.
In chapter 4 a model of the fuel cell stack is presented. It takes into account the gas flows in the different layers, describing membrane humidification as well as the voltage supplied by the fuel cell. The model also takes into account the influence of the membrane humidity on the stack voltage.
Among low temperature fuel cells, two technologies are available. The model is developed for the more common (Polymer Electrolyte Fuel Cell - PEFC), but the emerging technology (High Temperature Proton Exchange Membrane Fuel Cell - HTPEMFC) shows advantages with regard to system volume and heat use. Therefore, the models of the fuel processor and the fuel cell stack have been adapted to this emerging technology. The demonstrated adaptability underlines the advantage of using a modular modeling approach.

The models are validated successfully against measurements, literature values and values supplied by system manufacturer.
To confirm that the model can be used for model based control development, the control structure with regard to the temperature and the mass flow control for the FCS is developed in chapter 5. It is shown that the control structure of the system can be obtained by block wise inversion of the model. This approach gives the control structure; the choice of the controllers and their parameterization is up to the developer. The application of control proves that, using EMR, it is possible to derive a control structure from the model of a complex multi domain system without the need to derive its transfer function.

The presented work is accomplished in cooperation with the French national project GAPPAC from the PAN-H program of the French National Agency for Research (ANR). It gathers N-GHY, Airbus and Nexter as industrial partners and LMFA, Armines, IFFI, INRETS LTN and FCLAB Institute as research institutes.
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https://tel.archives-ouvertes.fr/tel-00358312
Contributor : Daniela Chrenko <>
Submitted on : Sunday, February 22, 2009 - 11:18:37 AM
Last modification on : Thursday, November 12, 2020 - 9:42:07 AM
Long-term archiving on: : Saturday, November 26, 2016 - 5:50:16 AM

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  • HAL Id : tel-00358312, version 3

Citation

Daniela Chrenko. Energetic Macroscopic Representation Modeling and Control of a Low Temperature Fuel Cell System Fed by Hydrocarbons. Electric power. Université de Franche-Comté, 2008. English. ⟨tel-00358312v3⟩

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