Mechanical Engineering Commons^™

Computational Simulation Of Mass Transport And Energy Transfer In The Microbial Fuel Cell System, Shiqi Ou

Doctoral Dissertations

This doctoral dissertation introduces the research in the computational modeling and simulation for the microbial fuel cell (MFC) system which is a bio-electrochemical system that drives a current by using bacteria and mimicking bacterial interactions found in nature. The numerical methods, research approaches and simulation comparison with the experiments in the microbial fuel cells are described; the analysis and evaluation for the model methods and results that I have achieved are presented in this dissertation.

The development of the renewable energy has been a hot topic, and scientists have been focusing on the microbial fuel cell, which is an environmentally-friendly …

Impurity Effects In All-Vanadium Redox Flow Batteries, Andrew William Burch

Masters Theses

In this dissertation, the effects of VOSO₄ [vanadyl sulfate] source and impurities on the beginning-of-life (BOL) performance of an all-vanadium redox flow battery (VRFB) are explored. Battery performance was monitored at 50% state of charge (SOC) using electrolyte with VOSO₄ purities of 99%, 99.9% and 99.99% by weight. At cell potentials of 1.23V, the least pure solution yielded the lowest current density of 280 mA/cm² [square centimeter] and the most pure solution yielded the highest, 560 mA/cm². The voltage efficiencies and charge-discharge capacities were shown to follow the same trends. Scanning electron microscopy (SEM) images …

Optimization Of Titanium Liquid/Gas Diffusion Layers In Proton Exchange Membrane Electrolyzer Cells, Stuart Mccoy Steen

Masters Theses

Polymer electrolyte membrane electrolyzer cells (PEMECs), which are reverse PEM fuel cells (PEMFCs), are effective energy storage medium by producing hydrogen/oxygen from water using electricity from renewable energy sources. This is due in part because of its efficiency, high energy density, compact design, and large capacity. In a PEMEC, a liquid/gas diffusion layer (LGDL) is located between the catalyst layer and the current distributing flow field. The LGDL is expected to transport electrons, heat, and reactants/products to and from the catalyst layer with minimum voltage, current, thermal, interfacial, and fluidic losses. Carbon materials (carbon paper or carbon cloth), typically used …

An Application Of Path-Percolation Theory And Lattice-Boltzmann Model On Mass Transfer In Inhomogeneous Porous Media, Ozgur Cekmer

Doctoral Dissertations

In this dissertation, random inhomogeneous porous channels were generated statistically, and single- and multi-phase flow models were developed to investigate diffusion behavior of gases in porous media. Three different methods were used to simulate inhomogeneous porous flow channels. First, the path-percolation theory was adapted in diffusion studies to generate random high-tortuosity (above 1.07) porous channels with a desired porosity within a specified confidence level. Cluster labeling process was applied to simulate paths for the gas molecules, and the resulting effective porosity was investigated statistically. Second, the double-path-percolation theory was introduced to simulate low-tortuosity (between 1.0005 and 1.0700) flow channels. Using …