Access Type

Open Access Dissertation

Date of Award

January 2013

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Mechanical Engineering

First Advisor

Howard N. Shapiro

Second Advisor

Trilochan Singh

Abstract

Plasma-assisted combustion (PAC) is a growing field of research that involves using nonthermal plasma (NTP) to enhance combustion. PAC research involves modeling reaction mechanisms and chemical kinetics. Exergy analysis of combustion devices focuses on combustion irreversibility, including mixing, internal heat transfer, and oxidation. This novel research project merges these two branches of research.

The focus of this work is the application of exergy analysis to PAC systems, to analyze the effect introducing NTP has on trends in exergy destruction associated with oxidation during hydrogen combustion. This was accomplished by developing a plug flow reactor model using the chemical simulation tool CHEMKIN-PRO® in conjunction with a reaction mechanism which includes explicit reaction pathways for NTP.

The primary results of the study identify an optimal range of exergetic efficiency when NTP composes between 0% - 20% of the oxidizer for a stoichiometric fuel-oxidizer ratio. Beyond 25% there is a dramatic reduction in the total exergy destruction before ignition. Additionally, the presence of NTP reduces the molar conversion of fuel while maintaining slightly higher than normal combustion temperatures, which results in an increase in the exit chemical flow exergy; presenting an opportunity to extract additional work. Finally, when NTP is introduced into the combustion process, it creates reaction pathways which dominate the production of key radicals and chain carriers that drive the trends in exergy destruction. A detailed understanding of these characteristics informs how NTP can be used to enhance combustion efficiency and reduce fuel use to achieve desired energy conversion.

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