Date of Completion

Spring 5-1-2020

Thesis Advisor(s)

Ugur Pasaogullari

Honors Major

Mechanical Engineering

Disciplines

Mechanical Engineering

Abstract

Fuel Cells are devices that use the chemical energy of a fuel (e.g. hydrogen) to electrochemically produce electricity. Similar to a conventual combustion engine, a fuel cell will continue to run and generate electricity as long as fuel is supplied. However, unlike a conventional combustion engine, fuel cells have a much higher theoretical efficiency and do not directly emit harmful air pollutants. This project will focus on a fuel cell that uses hydrogen as fuel and oxygen as an oxidizing agent.

As fuel cell technology evolved, high pressure fuel cell systems became of interest in portable applications, such as submarine oxygen generation, space station life support, or other places where oxygen is scarce. However, subjecting the fuel cell to such high pressures has had questionable results. Prior research in the field has shown that increasing operating pressure can increase voltage and power density, but can also introduce drawbacks such as increased gas permeation and water management issues.

The objective of this project is to investigate the thermodynamics of fuel cells to determine if there is a significant benefit to running fuel cells at very high pressures. Typically, fuel cells are run between 1-3 atm, but this project deals with pressure up to 160 atm. A thermodynamic model that includes the change in Gibbs free energy with high pressure and resulting thermodynamic potential increase was developed. The model included non-ideal gas behavior to accurately determine the potential benefits of high-pressure operation.

The results show that there are benefits, in terms of thermodynamics, in running hydrogen fuel cell systems at high pressures. However, this model only considers the thermodynamics; there may be other drawbacks that were not investigated.

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