In-flight air supply system for PEM fuel cells [Elektronische Ressource] / von Lukas Barchewitz

Lukas Barchewitz

Informations

• Publié par: gottfried_wilhelm_leibniz_universitat_hannover
• Publié le: 01 janvier 2008
• Nombre de lectures: 43
• Langue: English
• Poids de l'ouvrage: 2 Mo

Extrait

In-flight Air Supply System for PEM Fuel Cells



Von der Fakultät für Maschinenbau
der Gottfried Wilhelm Leibniz Universität Hannover
zur Erlangung des akademischen Grades
Doktor-Ingenieur
genehmigte Dissertation





von
Dipl.-Ing. Lukas Barchewitz
geboren am 09. Oktober 1975 in Kattowitz


2008








Stichworte

PEM-Brennstoffzelle, Fluganwendung, Luftversorgung, Turbomaschinenauslegung,
Auslegungsoptimierung, Regelung


Keywords:

PEM fuel cell, flight application, air supply, turbomachinery design, design
optimisation, in-flight controls




















Prüfungskommission:

Vorsitz: Prof. Dr.-Ing. B.-A. Behrens
1. Prüfer Prof. Dr.-Ing. J. Seume
2. Prüfer Prof. Dr.-Ing. A. Luke


Tag der Promotion: 11. Dezember 2007




Abstract
With on-going development of fuel cells and operational experience, fuel cells are
also considered for continuous power generation in the exigent flight application.
Here, low power specific weight and high electric efficiency are primary requirements.

The air supply system represents a core interface of the FC to the ambient, which
has impact on the operational range, stability and controllability of the FC system.
Radial turbomachinery is found to be most promising for the in-flight integration with
PEM-FC. The air supply system resembles a turbocharger, which is electrically
supported. A dedicated turbomachinery design is essential for an optimised operating
strategy regarding mass flow range, power demand, and system response.

Safe and quick transients of the air supply in combination with stack dynamic
operation are achievable. Application a decoupled controller improves the controller
performance and eliminates critical operating conditions for the compressor. The
controlled air supply system covers the entire operational range based on a reference
flight envelope and also handles extreme operating scenarios.
Kurzfassung
Aufgrund des fortschreitenden Entwicklungsstands und zunehmender
Betriebserfahrungen wird die Einsetzbarkeit von PEM-Brennstoffzellen in der
anspruchsvollen Fluganwendung untersucht. Bei der Anwendung zur kontinuierlichen
Bordenergieversorgung kommen einem geringen leistungsspezifischen Gewicht und
einem hohen elektrischen Wirkungsgrad eine besondere Bedeutung zu.

Das System zur Luftversorgung stellt das wichtigste Verbindungsglied mit der
Umgebung dar und beeinflusst Systemeigenschaften der Leistungseinheit wie
Betriebsbereich und Regelbarkeit. Radiale Turbomaschinen werden den
Anforderungen in dieser Anwendung gerecht, müssen jedoch für einen optimierten
Betrieb hinsichtlich des Betriebsbereichs, der Leistungsaufnahme und der
Systemdynamik gezielt ausgelegt werden. Die Anordnung der Turbomaschinen ist
der Turboladeranwendung entlehnt.

Unter Berücksichtigung der dynamischen Eigenschaften des Stacks kann das
Luftversorgungssystem schnell und zuverlässig geregelt werden. Eine Entkoppelung
erhöht die Regelgüte und umgeht kritische Betriebszustände im Verdichter. Der
Regler zeigt gutes Verhalten im ganzen Betriebsbereich einer Flugmission und deckt
auch extreme Lastwechsel ab.
I
Preface
This work is based on research carried out between 2003 and 2007 during my
appointment as research assistant at the Institute of Turbomachinery and Fluid
Dynamics at the University of Hannover, Germany. It was embedded in a
development strategy for the successful integration of PEM-FC technology into the
civil aircraft environment. Uwe Wollrab, Airbus Deutschland GmbH, and Peter
Schumann, DLR Stuttgart, are gratefully acknowledged for their support in flight-
specific and PEM-FC topics, respectively.

I am highly grateful to my supervisor Professor Jörg Seume for his guidance and help
throughout my time at the institute and the necessary support in initiating such a
promising research topic. Through him, I have learned how a structured co-operation
between research and industry can accelerate the development of new technologies.
My senior engineer Roman Pietrasch proved, along the way, to be an excellent
strategic advisor and has taught me not to forget the global goal of my work.

Thanks go to Tom Steglich, who was not just a good advisor on difficult topics on
radial compressors but more besides and to Katharina Fischer for the exchange of
ideas between us concerning fuel cell themes. Improvements of my work came from
many discussions with André Hildebrandt with whom I share a passion in
turbomachinery and their challenging combination with fuel cells. I would like to thank
Bastian Schreyer, Sebastian Kanzer, David Müller, Alexander Beil, and all my
colleagues who changed the institute from a working into a living place. Thanks go to
Katrin Erdmann for reviewing the script.

I want to thank Carsten Remmert who has stayed advisor and best friend.

I am deeply grateful to those who are most important in my life: My father and my
mother for the love and support in all my decisions. My wife, Céline, who stood
behind me during both the good and bad times of my thesis. And to my children,
Lea and Anna, for simply being.


Ad Maiorem Dei Gloriam



Hannover, September 2008
Lukas Barchewitz
III
Contents
Abstract ................................................................................................................................................... I
Kurzfassung............................................................................................................................................ I
Preface................................................................................................................................................... III
Contents.........................IV
Nomenclature........................................................................................................................................VI
1 Introduction................. 1
1.1 Background and Motivation .................................................................................................. 1
1.2 Objectives ............................................................................................................................. 3
1.3 Methodology.......................................................................................................................... 3
1.4 Overview ............................................................................................................................... 4
2 Conceptual Analysis of the Air Supply System.......................................................................... 6
2.1 Requirements and Boundary Conditions in the In-flight FC Application............................... 6
2.2 Application of Radial Compressors..................................................................................... 10
2.3 Application of the Turbocharger Architecture ..................................................................... 12
2.4 Integration of the Reformer Compressor ........................................................................... 13
2.5 Flight Operation at Varying Altitudes .................................................................................. 15
2.6 Operating Restrictions due to Extreme Ambient Conditions .............................................. 17
2.7 Operating Restrictions due to Aerodynamic Boundary Conditions..................................... 19
2.8 Increasing Operational Flexibility by Advanced System Design......................................... 21
2.8.1 Application of a Compressor Blow-off Valve .......................................................... 21
2.8.2 Application of Compressor Inlet Guide Vanes........................................................ 21
2.8.3 Application of a Post-combustor............................................................................. 21
2.8.4 Cathode Pressure Strategy .................................................................................... 22
2.9 Concept Choice and Further Approach .............................................................................. 23
3 Radial Compressor Design and Optimisation .......................................................................... 24
3.1 Design Strategy Considerations ......................................................................................... 24
3.2 Basic Aerodynamic Relationships and Non-dimensional Parameters................................ 25
3.3 Inducer Design.................................................................................................................... 29
3.4 Discharge Design................................................................................................................30
3.5 Diffuser and Volute Design ................................................................................................. 31
3.6 Design P