Framing a novel approach for pseudo continuous modeling using Direct Numerical Simulations (DNS): Fluid dynamics in a packed bed reactor

This research frames a novel approach to develop a pseudo-continuous model for describing the dynamics of a Newtonian fluid in an industrial-scale packed-bed reactor presenting a low tube to particle diameter ratio (dt/dp = 3.048) at particle Reynolds numbers ranging from 750 to 1750. The model accounts for the effect of compressional work on the pressure drop and the velocity field. The development of the pseudo-continuous model uses pseudo-steady-state local information obtained from Direct Numerical Simulations (DNS) to determine the so-called fluid dynamic descriptors. The suitability of the geometry configuration, determined from rigid body dynamic calculations, and particle-resolved simulations (PRS) is assessed by describing pressure drop observations and analyzing void fraction and velocity predictions. Local information related to the apparent permeability allows the development of a modified correlation to quantify solid-fluid frictional mechanisms. The pseudo-continuous model, developed by quantifying solid-fluid interactions with the use of either local information or the modified correlation, is able to describe properly velocity profiles obtained out of PRS. Velocity profiles predicted by the pseudo-continuous model are in agreement with those simulated by the Navier-StokesDarcy-Forchheimer equations. The density field and the divergence of the velocity field elucidate how fluid dynamics, along with the pressure drop, is affected by the fluid compressibility. The approach described here can be extended to complex pellet shapes, including the development of pseudo-continuous models for heat and mass transport, paving the way for the design of more efficient industrial-scale packed-bed reactors.

Automated summary

This study introduces a novel approach to developing a pseudo-continuous model for describing the dynamics of a Newtonian fluid in an industrial-scale packed-bed reactor with a low tube to particle diameter ratio. By incorporating compressional work into the pressure drop and velocity field, the model shows promise in accurately representing the behavior of the fluid. The research opens up possibilities for extending the approach to complex pellet shapes and developing pseudo-continuous models for heat and mass transport, thus paving the way for more efficient industrial-scale packed-bed reactors.