Doctoral Dissertations

Orcid ID

https://orcid.org/0000-0001-6380-3386

Date of Award

8-2024

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Mechanical Engineering

Major Professor

Matthew M. Mench

Committee Members

Matthew M. Mench, Douglas S. Aaron, Feng-Yuan Zhang, Vasilios Alexiades, Jacob Wrubel

Abstract

The increasing demand for renewable energy sources to replace fossil fuels, requires a growing need for a steady energy supply from source to power distribution. Renewable energy often relies on intermittent natural sources or is geographically bound, necessitating energy storage solutions. Polymer Electrolyte Water Electrolyzers (PEWEs) offer a promising solution but require performance enhancements for economic viability. This study focuses on applying distributed diagnostic techniques for PEWEs to gain insights into improving their performance.

The research aims to investigate transport phenomena in high-performance PEWEs, utilizing a segmented cell approach to probe different aspects of transport within a single cell. This diagnostic tool provides in-situ measurements of local performance, enabling a comprehensive understanding through the analysis of current density and high-frequency resistance distributions. The primary objective of this work is to leverage distributed diagnostics to characterize various diffusion media and flow-field designs, discerning their impact on various transport mechanisms. These findings will inform component redesign and performance optimization for efficiency and catalyst utilization.

Additionally, it introduces the concept of an "effective water transport number", providing a novel approach for characterizing water transport. Through distributed area specific resistance measurements, the research also seeks to quantify spatial variations of various overpotentials. Furthermore, this work investigates the bottlenecks and assesses the impact of flow-field design and architecture on localized transport to enhance the next generation designs of high-performance PEWEs. Finally, a LBM framework is presented to simulate the complex multi-scale bubble transport process at the pore-scale within the PTLs of a PEWE.

The successful achievement of these objectives deepens the understanding of high-performance PEWEs and the intricate aspects of various transport phenomena at play. It aims to provide valuable insights for optimizing cell operating conditions and long-term durability solutions. The experimental results not only serve as validation for modeling efforts; but also highlight the complex multi-physics phenomena governing these systems. Furthermore, better understanding of two-phase flow and the phenomenon of bubble detachment for the different type of porous transport layers contribute to the development of new generation, high performance diffusion media which ultimately leads to improved cell performance and reduced levelized cost of hydrogen.

keywords: PEM Electrolyzer, Porous transport layer, Current distribution, Water transport, Architecture

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