A study has been carried out on nitric oxide formation in hydrocarbon flames by chemical kinetics. Calculations of chemical equilibrium compositions were made using free-energy minimization method. It was found that this method could be appropriate for the prediction of NO formation when many species or reactions were considered.
Mathematical models proposed for the prediction of thermal NO have been examined and compared with experimental results. Comparison suggested that full kinetics could predict NO formation well compared to Zeldovich mechanism. On thermal NO formation, the effects of several parameters such as temperature, pressure, equivalence ratio, and type of fuel were investigated. NO kinetics as well as equilibrium compositions appeared to depend strongly on temperature.
An overall reaction model was proposed to predict prompt NO. Using this model, prediction of total NO including thermal NO together with prompt NO was made and showed good agreement with Fenimore's experiments in the range of φ = 0.9-1.4, and temperature T=1800-2100K.