Application of PAH-condensation reversibility in modeling soot growth in laminar premixed and nonpremixed flames

A new model for condensation of polycyclic aromatic hydrocarbons (PAHs) on the surface of soot particles is developed based on the reversibility of the process. Statistical mechanics has been integrated with a novel PAH condensation concept to estimate the PAH evaporation rate. This estimation has been used to develop a condensation efficiency model which is easy to implement, computationally efficient, and relies on physical parameters which can be evaluated. The new condensation model, combined with a reversible nucleation model (Eaves et al., 2015), is validated for predicting soot formation in both premixed and nonpremixed flames. The validations are followed by an extensive sensitivity analysis to evaluate the role of dominant soot processes as well as PAH chemistry on soot formation and particle size distribution (PSD). Simulations include a set of burner stabilized stagnation premixed flames and a coflow ethylene/air diffusion flame. This work is the first study which successfully utilizes a single soot model to quantitatively predict soot formation in both flame configurations.