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Redefinition of stack efficiency and optimization of stack performance for PEMFCs

Mitzel, Jens and Piela, Piotr (2016) Redefinition of stack efficiency and optimization of stack performance for PEMFCs. 21st World Hydrogen Energy Conference, 13.-16. Jun. 2016, Zaragoza, Spain.

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Abstract

In the first part of this work, we present a general redefinition of the PEMFC stack efficiency taking into account all power losses directly connected with the stack performance and the applied stack operating conditions. These are the stack fuel loss, the stack polarization- and reaction entropy- and enthalpy losses, and the theoretical losses for stack feed stream conditioning. In general, the latter includes humidification and pressurization (or pumping) of the reactants as well as pumping of the coolant. Furthermore, examples will be given which power losses are relevant for different applications and which are dominant and have to be considered. By the use of this new figure of merit, the efficiencies of two stacks can be compared to each other in a system-relevant way and can be determined for a given application scenario. In addition, the accompanying redefined balance-of-plant efficiency is a parameter characterizing uniquely the effectiveness of the BoP design and of the BoP components. In the second part of this work, a procedure for the optimization of the PEMFC stack performance will be highlighted. The performance of a stack at a given constant load strongly depends on the operating conditions characterized by 7 parameters. These are the stack temperature, the stoichiometric values of the reactants, the relative humidity of the reactants, and the pressures in both compartments of the stack. The effect of these parameters on the stack performance is non-linear and synergistic. A separate optimization of each single parameter is not meaningful. Therefore, a direct-search algorithm, the Nelder-Mead simplex, was used for the simultaneous optimization of all parameters.

Item URL in elib:https://elib.dlr.de/108059/
Document Type:Conference or Workshop Item (Speech)
Title:Redefinition of stack efficiency and optimization of stack performance for PEMFCs
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Mitzel, JensJens.Mitzel (at) dlr.deUNSPECIFIED
Piela, PiotricriUNSPECIFIED
Date:13 June 2016
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:PEMFC stack Efficiency Performance optimization optimization algorithm Melder-Mead simplex
Event Title:21st World Hydrogen Energy Conference
Event Location:Zaragoza, Spain
Event Type:international Conference
Event Dates:13.-16. Jun. 2016
HGF - Research field:Energy
HGF - Program:Storage and Cross-linked Infrastructures
HGF - Program Themes:Fuel cells
DLR - Research area:Energy
DLR - Program:E EV - Energy process technology
DLR - Research theme (Project):E - Electrochemical Processes (Fuel Cells) (old)
Location: Stuttgart
Institutes and Institutions:Institute of Engineering Thermodynamics > Electrochemical Energy Technology
Deposited By: Mitzel, Dr. Jens
Deposited On:22 Nov 2016 09:21
Last Modified:31 Jul 2019 20:05

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