High temperature polymer electrolyte membrane fuel cells
Christian Siegel
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Christian Siegel, High temperature polymer electrolyte membrane fuel cells (2015), Logos Verlag, Berlin, ISBN: 9783832598686
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Beschreibung / Abstract
A three-dimensional computational fluid dynamics model of a high temperature polymer electrolyte membrane fuel cell, employing a high temperature stable polybenzimidazole membrane electrode assembly doped with phosphoric acid, was developed and implemented using a commercially available finite element software. Three types of flow-fields were modeled and simulated. Selected simulation results at reference operating conditions were compared to the performance curves and to segmented solid-phase temperature and current density measurements. For the segmented measurements, an inhouse developed prototype cell was designed and manufactured. The segmented cell was successfully operated and the solid-phase temperature and the current density distribution were recorded, evaluated, and discussed. Sequentially scanned segmented electrochemical impedance spectroscopy measurements were performed to qualitatively support the observed trends. These measurements were used to identify and determine the causes of the inhomogeneous current density distributions. An equivalent circuit model was developed, the obtained spectra were analyzed, and the model parameters discussed. This work helps to provide a better understanding of the internal behaviour of a running high temperature polymer electrolyte membrane fuel cell and presents valuable data for modeling and simulation. For large fuel cells and complete fuel cell stacks in particular, well designed anode and cathode inlet and outlet sections are expected to aid in achieving flatter quantities distributions and in preventing hot spots over the membrane electrode assembly area, and to develop proper start-up, shut-down, and tempering concepts.
Inhaltsverzeichnis
- BEGINN
- 1 Introduction
- 2 Fuel cells
- 2.1 Working principle
- 2.2 HTPEM fuel cells
- 2.3 PBI/H3PO4 MEA
- 2.4 Overall features of a PBI/H3PO4 MEA
- 2.5 Future development
- 2.6 Fuel cell thermodynamics
- 2.7 Fuel cell characterization methods
- 3 PEM fuel cell modeling
- 3.1 Overall modeling aspects
- 3.2 HTPEM fuel cell models – Literature review
- 4 The developed HTPEM fuel cell model
- 4.1 Model geometry
- 4.2 Subdomain transport equations
- 4.3 Boundary conditions
- 4.4 Initial conditions
- 4.6 Assumptions and simplifications
- 4.6 Modeling parameters
- 5 Solving the model
- 5.1 Meshing
- 5.2 Solution procedure and convergence behaviour
- 6 The segmented HTPEM fuel cell
- 6.1 Segmented measurements – Literature review
- 6.2 Requirements, manufacturing and assembling
- 6.3 Measuring the solid-phase temperature distribution
- 6.4 Measuring the current density distribution
- 6.5 Segmented EIS measurements
- 6.6 Equivalent circuit modeling
- 6.7 Analysis of the EIS data
- 6.8 Operating the nonsegmented and segmented HTPEM fuel cell
- 7 Characterizing the three types of flow-fields
- 7.1 Fluid-flow distribution and pressure drop
- 7.2 Impedance measurements at no-load operating conditions
- 7.3 Overall performance at reference operating conditions
- 8 Segmented solid-phase temperature and current density measurements
- 8.1 Solid-phase temperature distribution at no-load operating conditions
- 8.2 Load operating conditions – Counter-flow configuration
- 8.3 Load operating conditions – Co-flow configuration
- 9 Segmented EIS measurements in a HTPEM fuel cell
- 9.1 Type I flow-field
- 9.2 Type II flow-field
- 9.3 Type III flow-field
- 10 Conclusion
- 10.1 Modeling and simulation
- 10.2 Experimental
- 10.3 Solid-phase temperature distribution
- 10.4 Current density distribution
- 10.5 Segmented EIS measurements
- 11 References