Transient heat and mass transfer in a wall-cooled packed-tray bioreactor for solid-state fermentation: An engineering framework for parameter estimation

Solid-state fermentation (SSF) of agrifood byproducts (AFBP) offers a sustainable route for producing high-value biomolecules, yet its industrial adoption is constrained by limited understanding of transport phenomena in wall-cooled packed bioreactors. Despite their potential for large-scale SSF, reliable methods for describing heat and mass transfer remain scarce. Building on previous fluid-dynamic studies, this work characterizes intrinsic transport mechanisms in a bench-scale wall-cooled tray packed with AFBP as substrate. An engineering framework not previously applied to these systems, integrating abiotic experiments, fluid dynamics, and transient analysis, was applied to estimate the effective thermal conductivity ( k eff ), wall heat transfer coefficient ( h w ), and axial dispersion coefficient ( D ax ). Experiments under conditions favorable to Yarrowia lipolytica 2.2ab (318.15 K, 60% moisture on a dry-weight basis, and inlet specific airflow rates, VkgM , of 1.875–6.250 L·kg⁻¹·min⁻¹) yielded values of 0.565–4.34 W·m⁻¹·K⁻¹ for k eff , 0.865–25.9 W·m⁻²·K⁻¹ for h w , and 2.60×10⁻³–5.30×10⁻³ m²·s⁻¹ for D ax . These results differ from previous SSF studies employing AFBP, highlighting the influence of reactor configuration, operating conditions, and parameter estimation approach. The proposed methodology provides a reliable framework for evaluating heat and mass transfer in SSF systems using AFBP as a substrate and establishes a foundation for predictive design and scale-up of packed bioreactors in biotechnological applications.