ORCID

0009-0001-6012-6874

Keywords

Ammonia Combustion, Alternative Fuels, Toroidal Jet-Stirred Reactor, Lean Blowout, Well Stirred Reactor, Carbon Emissions

Abstract

Due to rising concerns about global surface temperatures and carbon emissions, there has been an increased interest in studying alternative fuels. Ammonia and hydrogen are fuels with the potential to replace general biofuels, hydrocarbons, and sustainable aviation fuels, as they do not contain any carbon, eliminating carbon emissions. However, they are both difficult to work with. Hydrogen has great combustion characteristics such as low ignition energy, high flame speed and lower heating value. However, it is volatile and difficult to store, requiring it to be compressed to high pressure or cooled to incredibly low temperatures. Ammonia can be used as a carbon-free hydrogen carrier. It already has a widely established storage and transport infrastructure due to its usage in the farming industry. However, neat ammonia's poor combustion properties hinder its use as a fuel, having a significantly lower flame speed than hydrogen and common fuels such as Jet-A1, and having a much higher ignition energy. However, when mixed with a more reactive fuel such as hydrogen, improved sustainment and ignition can be seen. To further study these properties, a toroidal jet-stirred reactor was developed. This type of combustor was designed to reduce non-idealities such as hot spots, poor mixing, and concentration gradients, allowing for more chemistry-dependent flame studies. This work characterized a newly developed toroidal jet-stirred reactor and studied the flame stability conditions and lean blow-out stability limits of atmospheric turbulent ammonia-hydrogen flames for different concentrations and jet-ring inlet conditions. It was seen that at higher hydrogen concentrations and higher inlet temperatures, lean blow out occurred at lower equivalence ratios. Lean blowout was determined by a significant and sustained decrease in temperature, measured by thermocouples, or visual flame extinction. Neat ammonia was the most difficult to stabilize inside the jet-stirred reactor requiring a higher environment temperature to maintain a flame.

Completion Date

2026

Semester

Spring

Committee Chair

Subith Vasu

Degree

Master of Science in Mechanical Engineering (M.S.M.E.)

College

College of Engineering and Computer Science

Department

Mechanical and Aerospace Engineering

Format

PDF

Document Type

Thesis

Identifier

DP0053287

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