Analysis of Wet CO Oxidation under Turbulent Non-premixed Conditions Using a PDF Method and Detailed Chemical Kinetics

摘要

The oxidation of carbon monoxide in the presence of water under turbulent flow conditions is studied systematically for a detailed and global chemical mechanism. For this investigation, the PDF transport equation is employed to model the interaction of turbulent mixing and chemical reaction in a turbulent flow reactor. A 1100-K fuel stream and 900-K air oxidizer stream are mixed at different turbulent mixing times. Homogeneous and isotropic turbulence in an adiabatic reactor at constant pressure is assumed. Carbon monoxide conversion is modeled via a detailed mechanism containing 15 species and a global reaction. The PDF equation is solved using a Monte Carlo technique. From the numerical approximation of the PDF, equation is solved using a Monte Carlo technique. From the numerical approximation of the PDF, statical estimators of conversion for each reaction are calculated. From these, the influence of turbulent mixing on reaction paths is relvealed. The unclosed molecular diffusion term in the PDF transport equation is closed by a standard particle interaction modle and the binomial Langevin model extended to several scalars. The numerical results of both mixing models are compared and discussed. Both models predict a strong influence of turbulent mixing on the CO oxidation. The analysis of the reaction paths reveals that the production channels of the important intermediate species OH are shifted for varying mixing times. Furthermore, it is shown that the global mechanism can be applied for a limited range of initial ocnditions and characteristic turbulent times to model the CO conversion under turbulent conditions.