Influence of Particle Shape on Tortuosity of Non-Spherical Particle Packed Beds

Tortuosity in packed beds or porous media is of significant interest in many fields, from geoscience to the chemical industry. Tortuosity plays a significant role in the mass transport in porous media, but also in their residual thermal or electric conductivity when the particles are not conducting. Several predictive models have been proposed to evaluate tortuosity, but there is still a gap when it comes to considering various particle shapes. The preponderance of tortuosity models substantiated in the literature are porosity-dependent while only a few include shape parameters. In this work, we propose a new model with sphericity and porosity to predict the tortuosity based on thermal simulations carried out with non-conducting particles for domains with no wall effect. The beds generated from rigid body simulations are compared and studied for different particle shapes with a sphericity range of 0.65-1. Sphericity showed a significant effect on the tortuosity compared with other 3D shape parameters (numbers of faces, edges, and vertices); therefore, only sphericity has been considered in the new model. The proposed new model is well suited for the porosity range of 0.3 to 0.4. In said ranges, it is an upgrade of the classical Zehner-Bauer-Schlunder (ZBS) model for the effective thermal conductivity of packed beds, with superior performance.

Automated summary

Tortuosity, an important factor in packed beds or porous media, affects mass transport, thermal and electric conductivity. Current tortuosity models lack consideration for various particle shapes. This study proposes a new model that predicts tortuosity based on sphericity and porosity, demonstrating significant effects on thermal conductivity in different particle shapes. The new model shows superior performance in the porosity range of 0.3 to 0.4, making it an upgrade to the classical Zehner-Bauer-Schlunder (ZBS) model.