Decomposition and hydrocarbon growth processes for esters in non-premixed flames

Area of Science:

• Chemical Engineering
• Combustion Science
• Renewable Energy

Background:

• Biomass fuels are a key renewable energy source.
• Understanding combustion byproducts is crucial for safety and efficiency.
• Esters are components of biodiesel fuels, necessitating study of their combustion behavior.

Purpose of the Study:

• To investigate the decomposition mechanisms of specific C5H10O2 ester isomers in methane/air flames.
• To determine how ester molecular structure affects the formation of toxic oxygenated byproducts and aromatic hydrocarbons.
• To quantify the impact of ester doping on intermediate hydrocarbon concentrations and overall flame structure.

Main Methods:

• Experiments were conducted in atmospheric pressure coflowing methane/air non-premixed flames.
• Five specific C5H10O2 ester isomers were doped into the fuel mixture at 5,000 ppm.
• Analysis focused on changes in intermediate hydrocarbon concentrations to infer ester reaction pathways.

Main Results:

• Unimolecular six-centered dissociation was the primary pathway for three ester isomers.
• Simple fission appeared dominant for the other two isomers, though other pathways may contribute.
• All doped esters increased aromatic hydrocarbon formation compared to undoped fuel.
• Ester isomer structure influenced the yield and type of aromatic hydrocarbons and toxic oxygenates produced.

Conclusions:

• The molecular arrangement of ester isomers critically affects their decomposition pathways in flames.
• Ester combustion significantly influences the production of harmful byproducts, with isomer-specific variations.
• These findings are vital for optimizing biodiesel combustion and minimizing toxic emissions from biomass fuels.