Insights into Carbon Black Nanoparticle Formation within Flame Spray Pyrolysis Reactors by Numerical Modeling and Simulation

The Flame Spray Pyrolysis (FSP) process is a versatile and scalable method for controlled nanoparticle synthesis, with applications across various industrial sectors. FSP enables precise manipulation of nanoparticle properties, crucial for diverse applications. Carbon black (CB), important in emerging energy technologies like batteries and fuel cells, can be efficiently synthesized via FSP due to its controlled environment. Understanding CB formation is essential, given its impact on material properties. Computational Fluid Dynamics (CFD) simulations provide insights into nanoparticle formation and growth dynamics within FSP reactors, aiding in understanding process variables' influence. This study models and analyzes CB nanoparticle formation within a specific enclosed FSP reactor with controlled coflow. The modeling approach is validated through a benchmarking ethylene sooting flame, and results are compared with existing experiments and previous models. The model accurately describes soot formation in the benchmarking case, providing reliable predictions of temperature, soot, and mean particle size. After validation, the model is extended to the FSP case. Two- and three-equation models describe soot and CB formation, with particle dynamics thoroughly discussed. The semi-empirical models assume spherical primary particles, and in the three-equation model, a population balance transport equation is solved for primary particle number density. Our investigation includes parametric sensitivity analysis, highlighting the significance of reliable model parameters, including the radiative effects of carbon particles. This work advances the understanding and predictive modeling of CB synthesis via FSP, promoting simpler alternative models compared to intricate quadrature-solved population balance approaches in the literature.