With the rising cost of energy, the increasing environmental awareness and the global warming, alternative drive systems are becoming increasingly important. Here, the fuel cell technology makes as clean and reliable method of energy production a great contribution.
Many automotive companies like Hyundai, Daimler and Toyota are working intensively on fuel cell vehicles. Toyota has succeeded in December 2014 to bring the first car powered by hydrogen, the Toyota Mirai, on the market and it expects in the 2020s already with tens of thousands of vehicles annually.
Therefore, the sales numbers will be increasing, which will require a mass production of fuel cells.
Fuel cell technology is based on the principle of electrolysis. In order to generate electricity, hydrogen and oxygen are supplied to the fuel cell, where they react to electricity, water and heat. Thus cars powered by fuel cells have many advantages over cars with conventional sources, because they are environmentally friendly and save the long load time characterizing electric cars.
However, the current manufacturing way does not meet the requirements of mass production. To date, the components of the fuel cell are often assembled to a stack without sufficient testing, which significantly increases the potential for errors. After assembly, an end-of-line test is performed, wherein the fuel cell and its functions are checked up for up to 24 hours. To achieve higher production volume, the duration of the end-of-line tests must be reduced to a few minutes. This requires a total quality management and quality assurance during production in order to achieve a quick and error-free one. The aim of this work is to shorten the duration of the end-of-line test by the development of a montage accompanying control
plan.
The first part deals with the basics of the fuel cell technology. The most important historical events of the development of fuel cells are mentioned. In order to understand their functioning, the chemical and physical principles are explained and the functions of the individual components are described.
In the second part, a Failure mode and effect analysis (FMEA) is performed. Based on a literature review, this analysis aims at determining the most important errors in the components of the fuel cell. Its results deduce the most necessary test characteristics to be checked during the manufacturing of the fuel cell. [...]
Contents
1. Fundamentals of the fuel cell technology
1.1 History of fuel cells
1.2 Applications
1.3 Types
1.4 Principals
1.5 Structure and components of a PEMFC
1.5.1 Proton exchange membrane
1.5.2 Cathode/Anode catalyst layer
1.5.3 Gas diffusion layer
1.5.4 Bipolar plates
1.5.5 Front/End plates
2. Control Plan
2.1 Methodology
2.2 FMEA
2.3 Control parameters
2.3.1 Thickness variation of the MEA
2.3.2 Electrolyte cluster
2.3.3 Delamination
2.3.4 Catalyst cluster
2.3.5 Humidification
2.3.6 Cracking
2.3.7 Flow field structure in the bipolar plates
2.3.8 Tightness of the fuel cell
2.3.9 Temperature
2.3.10 Impedance
3. Control methods and plan
3.1 Cluster and cracks detection in the catalyst layer
3.1.1 IR thermography
3.1.2 Cluster detection with scanning electron microscope (SEM)
3.2 Flow field structure control of the bipolar plates
3.2.1 Image processing
3.3 Tightness control
3.4 Delamination control
3.5 Impedance control
3.5.1 High frequency resistance method
3.5.2 Current interrupt method
3.6 Membrane thickness control
4. Measurement uncertainties
4.1 Thickness measurement uncertainties
4.2 Impedance measurement uncertainties
4.3 Temperature measurement uncertainties
5. Conclusion and outlook
5.1 Conclusion
5.2 Outlook
Objectives and Research Themes
The primary objective of this work is to shorten the duration of end-of-line tests for PEM fuel cells to enable mass production, achieved through the development of a comprehensive, assembly-accompanying control plan. The study focuses on the following themes:
- Fundamental analysis of PEM fuel cell components and their operational requirements.
- Execution of a Failure Mode and Effects Analysis (FMEA) to identify critical manufacturing defects.
- Selection and evaluation of non-destructive, high-speed inline inspection technologies.
- Development of a monitoring system for key quality parameters such as thickness, tightness, and impedance.
- Assessment of measurement uncertainties to ensure reliable quality control resolution.
Excerpt from the Book
3.1.1 IR thermography
The configuration in the figure 17 can be used to detect catalyst failures such as clusters and cracks. This control method is based on the heat visualization at the surface of the catalyst layer using infrared (IR) thermography. It allows a complete, rapid (response in 1s for large areas), non-contact, and non-destructive detection of failures.
As shown in the figure 18, the reactants flow (a dilute non-flammable H2/O2 gas-mixture) is conducted through the gas diffusion electrode (GDE) − i.e. the gas diffusion layer (GDL), the micro porous layer (MPL), and the cataylst layer – to react on the Pt catalytic sites in the catalyst layer. The developed heat due to the reaction (the heat signature of the reaction) is captured by the IR camera through the IR transmitting material.
Summary of Chapters
1. Fundamentals of the fuel cell technology: This chapter covers the historical development, operating principles, and specific components of PEM fuel cells to provide a technical basis for the work.
2. Control Plan: This section details the FMEA methodology used to identify potential manufacturing defects and establishes the critical control parameters for production.
3. Control methods and plan: This chapter presents specific inline testing technologies, such as IR thermography, image processing, and EMAT, to monitor identified defects during assembly.
4. Measurement uncertainties: This section defines the relationship between measurement tolerances and uncertainties to determine the necessary resolution for inspection instrumentation.
5. Conclusion and outlook: The final chapter summarizes the findings regarding the reduction of end-of-line test durations and proposes future experimental validation steps.
Keywords
PEM fuel cell, mass production, quality assurance, FMEA, end-of-line test, IR thermography, EMAT, impedance control, manufacturing defects, electrolyte cluster, delamination, stack, catalyst layer, membrane, inline inspection
Frequently Asked Questions
What is the core focus of this thesis?
The thesis focuses on improving the quality assurance processes for the mass production of PEM fuel cells by reducing the time required for end-of-line testing.
What are the central thematic fields?
The research covers fuel cell component functionality, failure mode analysis, selection of inline inspection methods, and the determination of required measurement resolutions.
What is the primary research goal?
The goal is to develop a montage-accompanying control plan that minimizes the duration of end-of-line tests while maintaining high production quality.
Which scientific method is utilized?
The work utilizes a Failure Mode and Effects Analysis (FMEA) to identify defects, coupled with a literature review and the evaluation of state-of-the-art testing technologies.
What is addressed in the main body of the work?
The main body includes a structural and functional analysis of fuel cell components, a detailed FMEA, the design of a control plan using various diagnostic methods, and an analysis of measurement uncertainties.
Which keywords characterize the work?
Key terms include PEM fuel cell, mass production, quality assurance, FMEA, end-of-line test, and various detection technologies like IR thermography and EMAT.
How does IR thermography contribute to quality assurance?
IR thermography allows for rapid, non-contact detection of cracks and catalyst clusters by visualizing the heat signatures generated during the reaction process.
Why is the delamination control important for the stack?
Delamination between the catalyst layer and the membrane increases ionic resistance and heat generation, which significantly reduces performance and can lead to the formation of pinholes.
How does the EMAT technique facilitate high-speed inspection?
EMAT is a non-contact ultrasonic technique that allows for high-speed in-line scanning of multilayered structures without the need for couplants.
What is the significance of the "Rule of 10"?
The Rule of 10 illustrates that the cost of correcting a defect increases significantly the later it is detected in the product lifecycle, justifying early production-phase inspection.
- Citar trabajo
- Selmen Laabidi (Autor), 2015, Test methods for the quality assurance during the production of PEM fuel cells, Múnich, GRIN Verlag, https://www.grin.com/document/299917
