The effect of plasma discharge on methane diffusion combustion in air assisted by an atmospheric pressure microwave plasma torch

An atmospheric pressure air microwave plasma torch is employed to assist methane diffusion combustions using a combination of a combustor and burner. Experimentally, the effect of the air microwave plasma on combustion is investigated with respect to the flame morphology and the variation of gas components in the exhaust with the fuel equivalence ratio phi or the methane flow rate by comparing plasma-assisted combustion (PAC) and natural combustion (NC) without plasma application. The combustion degree of CH4 in PACs is found to be much enhanced in rich fuel combustion than in NC in both types of burners, which is measured by Fourier transformation infrared spectrometer (FTIR). In PACs, with the use of an air microwave plasma torch, the radicals originating from excitation, ionization, and dissociation of N-2 and O-2 and the high gas temperature induced in the plasma discharge play an important role in assisting the combustion.