Technical Report 25, c4e-Preprint Series, Cambridge

Modelling soot particle size distribution: Dynamics of pressure regimes

ref: Technical Report 25, c4e-Preprint Series, Cambridge

Associated Theme: Nanoparticles

Abstract

In this paper we present a stochastic algorithm designed for all relevant pressures to model the formation, growth and oxidation of soot particles. The stochastic method is used to solve the population balance equation that describes the various processes of soot formation, e.g., nucleation, coagulation, and surface reactions. We introduce a new generalized majorant kernel to exploit the method of fictitious jumps reducing the computational expense for the direct simulation algorithm. The implementation of the stochastic algorithm is validated against LSODE(Livermore Solver for Ordinary Differential Equation). We investigate laminar premixed flames to obtain the temporal evolution of the soot particle size distribution. The moments of these distributions are compared to the experimental measurements and existing numerical methods. A good agreement is observed. The effect of change in the C/O molar ratio on soot particle size distributions is discussed in the light of surface reactions contributing to the soot growth and oxidation. Also, it is demonstrated that the soot particle size distributions conform to the recent experimental observations, which link the nature of the distribution, i.e. bimodal, unimodal, to the peak temperature of the flame. A further study was done to show the importance of considering the different pressure regimes. A detailed description of the algorithm is given to facilitate its implementation by the reader.

Material from this preprint has been published in: Combustion and Flame 145 (3), 638-642, (2006)

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