Identifier

etd-07082008-111403

Degree

Doctor of Philosophy (PhD)

Department

Mechanical Engineering

Document Type

Dissertation

Abstract

The aim of the fuel cells part of this project was to investigate the performance of Proton Exchange Membrane Fuel Cells and closely related fuel cell types like the Alkaline Fuel Cells and Phosphoric Acid Fuel Cells. The investigation involved understanding the performance of fuel cells, addressing the shortcomings of currently used designs, and finding new methods for improving the performance of fuel cells. CFD was used to study flow channels and information learned from the study was used to design a new and improved flow channel. A prototype of the new design was fabricated, tested and found to perform better than conventional designs. Protons mass flow equation and equation for the diffusivity of hydrogen protons in PEM were derived. In addition, the effects of electrodes area ratio on selected fuel cells were studied theoretically and experimentally. The aim of the second part of this work was to model flow cytometers using fluent, which is the same CFD code used in the first part, and use the simulation result to optimize the design. Ren Yang [1, 2] designed the flow cytometers that were simulated. It was observed from the simulation results that blood cells were hydrodynamically focused within a range of sheath flow rate, and it was observed that bigger flow cytometer exit pipe diameter requires higher sheath flow rates for hydrodynamic focusing of blood cells. The simulation results were compared to the result from Ren Yang’s experiments and both results matched under the same flow conditions. Plots of the trajectories of blood cells, animation of the performance of the flow cytometer, and recommended operational flow rates for the given flow cytometer shape configurations were obtained from the simulation result. The simulation result was used to obtain an optimized design by making geometric configuration changes to correct the shortcomings in the original design. The optimized design was modeled and simulated. A comparison of the optimized design simulation results and the original design simulation results showed that the hydrodynamic focusing of the optimized design was better. Quantitatively, for a sheath flow of 0.000018 kg/s, the optimized design has 300% improvement in hydrofocusing effect compared to the original design.

Date

2008

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Tryfon T. Charalampopoulos

Share

COinS