Abstract
A chemical kinetics model-is developed for a CO2/N-2 microwave plasma, focusing especially on the vibrational levels of both CO2 and N-2. The model is used to calculate the CO2 and N-2 conversion as well as the energy efficiency of CO2 conversion for different power densities and for N-2 fractions in the CO2/N-2 gas mixture ranging from 0 to 90%. The calculation results are compared with measurements, and agreements within 23% and 33% are generally found for the CO2 conversion and N-2 conversion, respectively. To explain the observed trends, the destruction and formation processes of both CO2, and N-2 are analyzed) as well as the vibrational distribution functions of both CO2 and N-2. The results indicate that N-2 contributes in populating the lower asymmetric levels of CO2, leading to a higher absolute CO2 conversion upon increasing N-2 fraction. However, the effective CO2 conversion drops because there is less CO2 initially present in the gas mixture; thus, the energy efficiency also drops with rising N-2 fraction.