Effective reduction on flame soot via plasma coupled with carbon dioxide

Area of Science:

• Combustion Science
• Plasma Physics
• Chemical Engineering

Background:

• Soot emissions from diffusion flames are a major environmental concern.
• Carbon dioxide (CO2) and nitrogen (N2) are commonly used diluents in combustion.
• Non-thermal plasma is an emerging technology for pollutant control.

Purpose of the Study:

• To investigate the synergistic effects of non-thermal plasma and CO2 on flame soot characteristics.
• To analyze flame structure, temperature, and soot properties under various conditions.
• To understand the impact on soot nanostructure and graphitization.

Main Methods:

• Experimental study of diffusion flames diluted with CO2 or N2.
• Inclusion of non-thermal plasma in the presence and absence of diluents.
• Analysis of flame structure, temperature distribution, and soot characteristics (nanostructure, graphitization) using optical methods and Raman spectroscopy.

Main Results:

• CO2 dilution resulted in lower flame temperatures compared to N2 dilution due to higher specific heat capacity.
• The combination of plasma and CO2 led to the lowest soot concentration, indicating a synergistic inhibitory effect.
• CO2 dilution, especially at low oxygen concentrations, produced amorphous soot with lower graphitization and shorter fringe lengths and higher tortuosity in the presence of plasma.

Conclusions:

• Plasma coupled with CO2 exhibits a synergistic effect in suppressing soot emissions.
• The nanostructure of soot is significantly altered by plasma and CO2, leading to reduced carbonization.
• This combined approach is effective for mitigating soot formation in diffusion flames.