(571f) Development of a Micro Kinetic Model of Soot for Ethylene Flames | AIChE

(571f) Development of a Micro Kinetic Model of Soot for Ethylene Flames


Sundar, S., Indian Institute of Technology, Madras
Chakravarthy, S. R., Indian Institute of Technology, Madras

Srivathsan PS1 ,Preeti Aghalayam1 and S. R. Chakravarthy2

1Dept. of Chemical Engineering, Indian Institute of Technology, Madras

2Dept. of Aerospace Engineering, Indian Institute of Technology, Madras

Corresponding author: preeti@iitm.ac.in

Soot, a carbonaceous material formed from the thermal decomposition of the hydrocarbons is considered to be one of the most important pollutants to be assessed. The major contributor of the pollutant is the heavy duty diesel engine. The impact of the carbonaceous material on the atmosphere is very alarming. Soot contains particles in which 75% of its content is less than 2.5micrometer. The particles less than the above-mentioned size can easily get adsorbed onto the human lungs during respiration and can cause cancerous growth. So there is a need for the soot concentration to be controlled, particularly from automobiles.

Various reaction pathways are proposed in the literature for the conversion from fuel to soot. The fuel undergoes pyrolysis and further addition reactions to end up in polyaromatic hydrocarbons. These formed PAH starts nucleate and undergo mass growth to finally end up in what is called mature soot. As there are many proposed pathways for soot formation, there is a great demand for detailed microkinetic modelling and analysis.

In this work, a gas phase reaction mechanism containing the flame and precursor chemistry for ethylene/air systems has been implemented in order to obtain the gas-phase soot precursor concentrations at different operating conditions. A surface mechanism has also been implemented in order to capture the particle nucleation and particle growth processes. A premixed laminar burner stabilised stagnation flame with an equivalence ratio of 2.07 is simulated, based on availability of experimental data in literature. The numerical simulation was performed under the stagnation flame conditions using the one-dimensional commercial code, CHEMKIN.

A sectional approach was implemented to generate particle size distribution function. We have incorporated around 1300 gas phase reactions and 8 surface reactions to obtain the soot precursor concentration and to generate PSDF. The simulated flame temperature and precursor concentration were in good agreement with the data in the literature. The simulated PSDF was found to reproduce the trend available in experimental for various heights above the burner surface. In this work, we propose to develop and analyze the detailed reaction kinetic model for soot formation process incorporating all the above processes, for fuel-rich ethylene/air flames.