Fractal Kinetic Analysis of Biomass Hydrothermal Carbonization

This paper introduces fractal analysis to study the kinetics of biomass hydrothermal carbonization. The reacting water-biomass slurry is a complex system leading to hydrochar by microscale reactions constrained into fractal topological boundaries. Literature and purpose experimental data check equations adapted from the fractal-like repertoire. More general models are derived from a shortcut, stochastic-based formalism, avoiding the mathematical sophistication of fractal calculus. Fractal equations explain observed data better and with fewer parameters than traditional mass-action network models (0.91202 < R (2) < 0.99998, average 0.97957) over a wide range of biomass and operational conditions. Exploratory experiments highlight the surface fractal dimension of hydrocars and their variation concerning that of parent biomasses (from 2.00 to 2.84). The confluence of fitting success and evidence of HC fractality encourages prosecuting research for making fractal kinetics a fully fledged tool of hydrothermal carbonization studies.