Computational fluid dynamics simulation of pressure drop and macromixing in LL microreactors

Abstract

AbstractA computational fluid dynamics (CFD) model was developed to simulate single‐phase flow in LL microreactors using the open‐source software OpenFOAM. The k‐ω SSTLM turbulence model was implemented to account for the impact of small‐scale temporal and spatial fluctuations that emerge in the base LL mixing module (LLM) on the flow field and transport of a passive scalar. The CFD model was successfully validated based on excellent conformance to experimental pressure loss (R2 > 0.997) and residence time distribution (RTD) data (R2 > 0.97) at flow rates ranging from 10‐100 g/min. Streamlines, velocity, pressure, and turbulent viscosity profiles were mapped across the 3D domain of repeating reactor segments to analyze local fluid dynamics. In a continuous series of LLMs, the flow field becomes fully developed after the second module. A drastic change in flow behaviour in the LLM was identified at 30 g/min (Re = 643) based on the emergence of advective recirculation zones and significant turbulent dispersion. Recirculation zones in the LLM grow larger from 20‐50 g/min and are equal in size from 50‐100 g/min. Four LL reactor plates with differing configurations of spacing between LLMs were compared extensively by analyzing pressure drop and RTD. Plates with continuous or equally‐spaced LLMs demonstrated a near plug‐flow profile with minor dispersion (Pe > 100), albeit at a greater power dissipation. Plates with longer residence‐time channels between LLMs yielded a broader and right‐skewed RTD due to the intermittent attenuation of chaotic flow patterns.