Coarse-Grained Models for Scale-Up of Structured Reactors

Computational fluid dynamics (CFD) simulations of structured reactors provide insight into the complex interplay between reaction kinetics and momentum, heat, and mass transport and could be used for optimization and scale-up. However, CFD simulations are limited to small computational domains and are too computationally intensive for large systems comprising small geometric features. In this work, we develop a reduced-order model for flow and heat transfer in monoliths using volume averaging by incorporating temperature-dependent thermophysical and transport properties and correlations under periodic and nonperiodic boundary conditions to handle monolith edge effects. The model agrees well with CFD. We apply the model to scale up monolith reactor stacks for natural gas processing. We compare temperature gradients in monoliths made of various materials (SiC, SiO₂, and Cu). Unexpectedly, highly conducting monoliths, such as silicon carbide, could have low energy efficiency when their emissivity is high. We discuss mitigation strategies to improve energy efficiency.