Volume‐of‐fluid‐based model for multiphase flow in high‐pressure trickle‐bed reactor: Optimization of numerical parameters

Abstract

Aiming to understand the effect of various parameters such as liquid velocity, surface tension, and wetting phenomena, a Volume-of-Fluid (VOF) model was developed to simulate the multiphase flow in high-pressure trickle-bed reactor (TBR). As the accuracy of the simulation is largely dependent on mesh density, different mesh sizes were compared for the hydrodynamic validation of the multiphase flow model. Several model solution parameters comprising different time steps, convergence criteria and discretization schemes were examined to establish model parametric independency results. High-order differencing schemes were found to agree better with the experimental data from the literature given that its formulation includes inherently the minimization of artificial numerical dissipation. The optimum values for the numerical solution parameters were then used to evaluate the hydrodynamic predictions at highpressure demonstrating the significant influence of the gas flow rate mainly on liquid holdup rather than on two-phase pressure drop and exhibiting hysteresis in both hydrodynamic parameters. Afterwards, the VOF model was applied to evaluate successive radial planes of liquid volume fraction at different packed bed cross-sections.

Computational Flow Modelling of Multiphase Reacting Flow in Trickle-bed Reactors with Applications to the Catalytic Abatement of Liquid Pollutants

“…An introductory parametric optimization was also accomplished querying the effect of different differencing schemes on the momentum and volume fraction balance equations. High-order differencing schemes based on Compressive Interface Capturing Scheme for Arbitrary Meshes (CICSAM) and High Resolution Interface Capturing (HRIC) schemes were found to agree better with the experimental data from the literature given that its formulation includes inherently the minimization of artificial numerical dissipation as described elsewhere (Lopes & Quinta-Ferreira, 2009). We begin with a base case querying the influence of numerical solution parameters including different mesh apertures.…”

“…This task is sought to be accomplished by the experimental work devoted to investigate the suitability of this methodology as well as by state-of-the-art simulation tools considered by CFD codes. The case study encompasses the application of a trickle-bed reactor to the detoxification of phenolic wastewaters through a series of experimental runs accompanied and validated by a multiphase Volume-of-Fluid (VOF) model formerly reported (Lopes & Quinta-Ferreira, 2009). At a first glance, a brief prospect of literature on trickle-bed reactor modelling and validation is presented at reaction conditions.…”

Numerical simulation of reactive pulsing flow for the catalytic wet oxidation in TBR using a VOF technique

“…In the present work, we have used the polynomial form of the criterion presented by Attou and Ferschneider 10 coupled with the model originally investigated by Lopes and Quinta-Ferreira. 17 Continuity and momentum Eqs. 1 and 2 are functionally equivalent to the set of equations used by Grosser et al, 6 which were implemented in C language in the CFD framework for the trickle-to-pulse transition.…”

“…17 It consists of a cylindrical vessel with 5-cm internal diameter and 1-m bed height packed with catalyst spherical particles 2-mm diameter. The catalytic bed is meshed in tetrahedral cells by means of the FLUENT preprocessor GAMBIT 2.…”

Numerical assessment of diffusion–convection–reaction model for the catalytic abatement of phenolic wastewaters in packed-bed reactors under trickling flow conditions

“…Notwithstanding these values make these meshes inappropriate for using an standard wall 24 function, except for the cases at low Reynolds, FLUENT solver allows the range for wall The multiphase reactor in our trickle bed pilot plant comprises a cylindrical geometry with the 3 following dimensions 50 mm of internal diameter and 1.0 m length and the experimental 4 procedure has been described elsewhere (Lopes & Quinta-Ferreira, 2010 A c c e p t e d M a n u s c r i p t 16 schemes were found to agree better with the experimental data from the literature given that 1 its formulation includes inherently the minimization of artificial numerical dissipation as 2 described elsewhere (Lopes & Quinta-Ferreira, 2009 In order to properly capture the boundary layer now on the temperature profile and regarding 5 also the mesh sensitivity analysis, several computational runs were additionally performed 6 changing the mesh density on the catalyst particle surface. The effect of mesh aperture on the 7 thermal behavior of the trickle-bed reactor is portrayed in Fig.…”