CFD simulation of industrial flares with reduced mechanism and nitrogen oxides dispersion from vehicular exhaust pipe.

摘要

The present study applies Computational Fluid Dynamics (CFD) techniques to predict the fate of pollutants released from the two main sources of air pollution---industrial flares and vehicular exhausts. In Part I of the thesis, the combustion of industrial flares was simulated using the commercial CFD code FLUENT 6.3. The effect of varying the fuel inlet velocity and crosswinds on the fuel combustion efficiency, which is overestimated in the practical world, is analyzed. The discrepancy in the report of actual pollutant emissions and emission inventory from industrial flares is studied using the numerical method. CFD simulation is used to aid the analysis of speciation of industrial flares, which is difficult and expensive to measure in real-world conditions. CFD simulation of a detailed chemical kinetic mechanism containing numerous species and reactions is computationally very expensive. The detailed mechanisms are reduced in this work using the commercial software, CARM. A new technique, CARMex, is developed to tailor the reduction of reaction mechanism with particular focus on the specie of interest. In Part II, a three-dimensional numerical model based on the Reynolds-Averaged Navier-Stokes equation with k-epsilon turbulence model is used to predict the fate and dispersion of the NOx plume from the vehicular exhaust pipe at different traffic conditions. This numerical model was developed as a preliminary step to study the effect of laying photocatalyst-coated roads on NOx removal; thus, reducing the ground-level ozone. The developed model successfully predicted the concentration of NO and NO2, and temperature along the downstream position from the exit source. The analytical model presented in this work will act as a guideline for future numerical modeling and experimental work to study the interaction between photocatalytic coated roads and NOx.