Numerical Analysis of Heat Transfer in a Modular Biomass Reactor: CFD-based Validation and Two-state Feedback Control Modeling

The transition toward sustainable energy relies on efficient biomass conversion technologies. In this context, developing advanced technologies for solid biofuel testing is essential to achieve greater process control and experimental reliability. Addressing this need, this study presents a Computational Fluid Dynamics model, serving as a Digital Twin for a modular bench-scale biomass reactor. Implemented in COMSOL Multiphysics, the model characterizes coupled heat transfer phenomena. A key innovation is the integration of a two-state feedback control logic that accurately replicates dynamic heater power switching. The numerical model was validated against transient thermocouple data. Considering thermal radiation was essential to reproduce experimental behavior, while mesh independence tests confirmed stability of outputs with less than 0.05% deviation. The validated simulation successfully mapped internal thermal dynamics, revealing longitudinal temperature gradients with maximum temperatures concentrated in the lower chamber region. This insight solved the sample placement challenge by pinpointing the optimal heating zone for the crucible. Ultimately, this Digital Twin operates as a reliable, non-intrusive diagnostic tool. The model is already accelerating research and development cycles by serving as the baseline for new experimental setups, demonstrating the value of advanced modeling in the optimization and digitalization of thermochemical systems.