Numerical investigation of the effect of water vapor diluent injection on the formation of NO_x pollutants

Abstract

In this paper, the eddy dissipation model was used to predict the exact behavior of reacting flow in a round jet burner. The results were validated and verified with available experimental and numerical data. To this end, the turbulence and combustion equations were solved using the k-ε/EDM model and the PIMPLE algorithm by means of OpenFoam package. In addition, by modifying the reactingFoam solver, the thermal NO_x equations were solved, and the equations of the P-1 radiation model were used to solve the radiation equations. After validating the numerical method, the effects of H₂O diluent injection rate and its location were studied on the temperature distribution and NO_x emission. The results revealed that as the injection rate of water vapor diluent increased, the temperature of the fluid decreased, and a decrease was observed in NO_x emissions in proportion to the temperature reduction. Increasing the diluent injection velocity had a negligible effect on the similarity distribution of temperature and NO_x mass fraction and the location of the maximum temperatures did not change much. The effects of diluent injection on reducing NO_x pollution were also seen upstream. As the diluent injection velocity increased, the effect of the diluent on the NO_x emission gradually were diminished.

Keywords:

• Dilution
• H₂O injection
• Non premixed flame
• NO_x emission
• temperature reduction