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Date of Award
Doctor of Philosophy in Mechanical Engineering-Engineering Mechanics (PhD)
College, School or Department Name
Department of Mechanical Engineering-Engineering Mechanics
In a proton exchange membrane fuel cell (PEMFC) mass is transported in three directions- 1) through-plane 2) land-channel, and 3) flow-channel. In all these directions, because of the non-uniform distribution of oxygen and hydrogen the current density distribution is non-uniform which translates to uneven water generation and ohmic resistance distribution. These non-uniformities affect the overall power density and efficiency of the fuel cell. In the recent decade, segmentation of PEMFC in the flow-channel direction became an indispensable diagnosis tool to study mass transport losses but are limited to flow-channel direction. So the objective of this Ph.D. work is to develop an experimental technique to the segment PEMFC in the land-channel direction and study the mass transport losses in the land-channel direction.
To achieve this target PEMFC is segmented in the land-channel direction and parameters such as current density, electrical resistance, electrochemical surface area, and ohmic resistance distribution were measured at 350 μm resolution of 1 mm wide land and channel configuration flow field. Three novel designs of segmented PEMFC were examined to measure these parameters: 1) First generation plug-in segmented anode 2) Second generation plug-in segmented anode and 3) μ segmented anode flow field. First and second generation plug-in segmented are designed to insert in large scale fuel cell to study local mass transport losses and μ segmented anode flow field is introduced to further simplify experimental set-up. Later two designs demonstrated success and were validated by conducting series of in-situ and ex-situ tests.
Second generation plug-in flow field and μ segmented anode flow field applied to measure current density distribution in land-channel direction in wet, extremely dry, and moderate conditions. In addition, to these designs an experimental set-up to measure ohmic resistance distribution in conjunction with current density distribution is demonstrated. A methodology is described to use current density and ohmic resistance distribution data to analyze the effect of land-channel geometry on estimating oxygen concentration, membrane water content, and oxygen transport resistance distribution in moderate and dry conditions, and in dry condition cathode electrode resistance and membrane water content. This technique further applied to interdigitated flow field.
Shrivastava, Udit N., "SEGMENTATION OF PROTON EXCHANGE MEMBRANE FUEL CELL IN THE LAND-CHANNEL DIRECTION", Dissertation, Michigan Technological University, 2015.