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Reliable optimization of the PEMFC stack efficiency for automotive application

Mitzel, Jens and Piela, Piotr and Schulze, Mathias and Friedrich, Kaspar Andreas (2017) Reliable optimization of the PEMFC stack efficiency for automotive application. 7th International Conference on ”Fundamentals & Development of Fuel Cells”, 01.-03. Mar. 2017, Orleans, France.

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The operating conditions essentially determine the performance and the efficiency of a polymer electrolyte membrane fuel cell (PEMFC) stack in an automotive system. Due to space and weight limitations in such systems, an optimization is mandatory to assure high power output and fuel utilization. Typically, the operating conditions are defined in a system by look-up tables and are not adapted over stack lifetime. But the best operating conditions can vary over the lifetime due to the presence of different degradation phenomena, e.g. resulting in changes of the electrode structure, the electrode hydrophobicity, and the catalyst activity. Predefined tables cannot cover this behavior and the use of optimization algorithms is highly favorable to facilitate optimal stack operation during entire lifetime. In the presented work, n*(stack) is defined to represent the stack efficiency in a system because the commonly used stack electrical- and fuel efficiencies do not consider the operating conditions. This new efficiency covers all power losses based on the applied conditions including theoretical losses for stack feed stream conditioning. An example is given which power losses are relevant and dominant for automotive application. The performance and efficiency determining conditions are characterized by the stack temperature as well as the stoichiometric values, the relative humidity, and the pressures of the reactants. Their effect is non-linear and synergistic. A separate optimization of the parameters is not meaningful. Therefore, a direct-search algorithm, the Nelder-Mead simplex, was used for the simultaneous optimization of all parameters. The algorithm was realized using harmonized test procedures elaborated in the Stack-Test project to assure reliable and reproducible parameter optimization. The optimization process and the used test procedures are explained in detail and presented results demonstrate that the efficiency can be improved in a running PEMFC stack by up to 4 % only by optimizing the operating conditions in an automotive system.

Item URL in elib:https://elib.dlr.de/113756/
Document Type:Conference or Workshop Item (Speech)
Title:Reliable optimization of the PEMFC stack efficiency for automotive application
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Mitzel, JensJens.Mitzel (at) dlr.dehttps://orcid.org/0000-0001-8137-9689
Piela, PiotricriUNSPECIFIED
Schulze, MathiasMathias.Schulze (at) dlr.deUNSPECIFIED
Friedrich, Kaspar AndreasAndreas.Friedrich (at) dlr.deUNSPECIFIED
Date:2 March 2017
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:No
Keywords:PEMFC Performance Efficiency Optimization Nelder-Mead algorithm
Event Title:7th International Conference on ”Fundamentals & Development of Fuel Cells”
Event Location:Orleans, France
Event Type:Workshop
Event Dates:01.-03. Mar. 2017
HGF - Research field:Energy
HGF - Program:Storage and Cross-linked Infrastructures
HGF - Program Themes:Fuel cells
DLR - Research area:Energy
DLR - Program:E SP - Energy Storage
DLR - Research theme (Project):E - Electrochemical Processes (Fuel Cells)
Location: Stuttgart
Institutes and Institutions:Institute of Engineering Thermodynamics > Electrochemical Energy Technology
Deposited By: Mitzel, Dr. Jens
Deposited On:29 Nov 2017 15:33
Last Modified:31 Jul 2019 20:11

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