Technical Report 4, c4e-Preprint Series, Cambridge

Authors: Michael Balthasar and Markus Kraft*

Reference: Technical Report 4, c4e-Preprint Series, Cambridge, 2002

Associated Themes:
 

In this paper we introduce an efficient stochastic approach to solve the population balance equation which describes the formation and oxidation of soot particles in a laminar premixed flame. The approach is based on a stochastic particle system representing the ensemble of soot particles. The different processes contributing to the formation and oxidation of soot particles are treated in probabilistic manner. The stochastic algorithm, which makes use of a very efficient majorant kernel and the method of fictitious jumps resolves the entire soot particle distribution (PSDF) without introducing additional closure assumptions. A fuel rich laminar premixed flame of acetylene is computed using a detailed kinetic soot model. Solutions are obtained for both, the stochastic approach and the method of moments combined with a modified version of the code Premix which is part of the CHEMKIN package. In this manner, for the first time, the accuracy of the method of moments in a real flame is investigated. It is found that the accuracy for the first moment is excellent (5% error), and mean error for rest of the moments is within 25%. Also the effect of the oxidation of the smallest particles (burnout) has been quantified but was not prominent in the flame investigated. The time evolution of computed size distributions as well as integral values are compared to experimental measurements and the agreement was found to be satisfactory. The results show that the PSDF of soot particles is bimodal. Finally, the efficiency of the method is studied.

PDF (1.1 MB)