Date of Award

Spring 2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical & Aerospace Engineering

Committee Director

Ayodeji O. Demuren

Committee Member

Miltiadis Kotinis

Committee Member

Sandeep Kumar

Abstract

Three-Dimensional proton exchange fuel cell (PEMFC) operation in steady-state is simulated with computational fluid dynamics / multiphysics software that is based upon the finite-element method. PEMFC operation involves the simultaneous simulation of multiple, interconnected physics involving fluid flows, heat transport, electrochemical reactions, and both protonic and electronic conduction. Modeling efforts have varied by how they treat the physics occurring within and adjacent to the membrane-electrode assembly (MEA). Several approaches treat the MEA as part of the computational domain, solving multiple, and coupled conservation equations via the CFD approach within the 3 regions of the MEA. The thickness dimensions of the 3 regions of the MEA can be 2 orders of magnitude less than the features of the neighboring flow channels. Though this approach has been commercialized, the computational costs are quite high, due to the presence of large numbers of high-aspect ratio cells within the thin MEA. Research into the underlying physical phenomena, such as water transport, has also progressed, suggesting that various modeling errors may undermine many previous approaches. Other approaches treat the MEA as an interface, where they avoid these difficulties, but lose the ability to predict catalyst layer losses. This study develops an upgraded interface formulation where coupled water, heat, and current transport behaviors of the MEA are modeled analytically. Improving upon previous work, catalyst layer losses can now be modeled accurately without the ad-hoc changes in model chemical kinetic parameters. The interface model is developed considering only thru-plane variation, based upon varied fundamental research into each of the relevant physics. First, the model is validated against differential cell data with high and low humidity reactants. Validation continues with full 3-D test cases with different current levels and inlet conditions. Distributed data of current density are used to show model agreement with experimental data.

ISBN

9780355883930

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