A Novel hybrid kinetic–equilibrium model for predicting syngas composition in coal char gasification: Coupling thin reaction zone kinetic with Gibbs free energy minimization

This study develops and applies new approach regarding an integrated modeling framework that combines the Thin Reaction Zone (TRZ) kinetic model with the Gibbs free energy minimization (GFEM) thermodynamic model to predict the gas composition during the gasification of coal char. The TRZ model describes the kinetics of heterogeneous gas–solid reactions by considering the variation of the unreacted core region and mass transfer phenomena, while the GFEM model determines the equilibrium gas composition based on thermodynamic constraints. The coupling of these two models enables a more comprehensive representation of both reaction dynamics and equilibrium behavior in the gasification process. Simulations were conducted at operating temperatures of 600 °C, 700 °C, and 800 °C, and the results were validated against experimental data. The predicted gas compositions showed good agreement with the measured values, with mean relative errors of 7.46%, 19.17%, and 11.05% for 600 °C, 700 °C, and 800 °C, respectively. These relatively low error values demonstrate that the hybrid TRZ–Gibbs approach can effectively capture the complex physicochemical mechanisms occurring in coal char gasification. The integrated model thus provides a valuable tool for process analysis, performance evaluation, and optimization of operating parameters, offering strong potential for improving gasifier design and operation in future clean energy systems.