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Through Euler/Euler large eddy simulation (LES) modeling, it is demonstrated that turbulent dispersion of bubbles can effectively indicate the impact of turbulent eddies on the bubble dynamics, i.e., the bubble oscillation behavior. This finding builds on previous work using the Euler/Lagrange LES modeling approach and leads to a significant improvement in predicting bubble lateral dispersion. Spatially filtered terms were proposed for the subgrid‐scale (SGS) turbulent dispersion and added mass stress force models, with a modification made to the SGS eddy viscosity to reflect bubble turbulent dispersion and oscillations. The proposed model substantially improves the prediction of bubble volume fraction distribution, bubble and liquid phase velocity profiles, the turbulent kinetic energy spectrum, and mass transfer. [ABSTRACT FROM AUTHOR]

• E-E LES modelling on three CO 2 chemisorption cases in bubble columns was conducted. • Modified SGS turbulent dispersion (TDF) and added mass stress (AMS) models proposed. • Impacts of the SGS-TDF and SGS-AMS terms on the interfacial mass transfer were assessed. • Scaling laws of turbulent kinetic energy and species concentration spectra were discussed. It has been generally recognised that the turbulent dispersion force plays an important role in interphase momentum transfer. However, the effect of the added mass stress on the momentum and mass transfer in bubble column bubbly flow has not been addressed appropriately. As the turbulent eddies in the surroundings of bubbles interact strongly with the rising bubbles in bubble column bubbly flow, such interactions will bring out the change of interfacial areas between the bubbles and carrier fluid, consequently leading to changes in the interfacial mass transfer. When employing large eddy simulation for modelling bubbly flow coupled with the chemisorption process, the SGS filtered velocity fluctuations of liquid phase can be interpreted as the turbulent eddies that continuously hit the surfaces of bubbles, causing bubble deformation and the variation of bubble interfacial areas, which give rise to the turbulent dispersion and added mass stress forces. The present study will demonstrate through Euler/Euler large-eddy simulations (LES) modelling that by considering the turbulent dispersion force (SGS-TDF) and added mass stress (SGS-AMS), the bubble dynamics and mass transfer under the chemisorption conditions can be better indicated, which leads to remarkable improvements in the prediction of bubble lateral dispersion and the interfacial mass transfer. The turbulent dispersion and added mass stress related to the spatially filtering were proposed with a modification on SGS eddy viscosity to reflect turbulent dispersion due to bubble-induced turbulence. A comprehensive assessment of the effects of these additional filtered stress terms on the time-averaged velocity and bubble volume fraction profiles, flow patterns, mass transfer and the pH variation during CO 2 chemisorption and the turbulent kinetic energy and species concentration spectra was conducted. [ABSTRACT FROM AUTHOR]

FePO 4 (FP) particles with a mesoporous structure amalgamated by nanoscale primary crystals were controllably prepared using an ultrasound-intensified turbulence T-junction microreactor (UTISR). The use of this type of reaction system can effectively enhance the micro-mixing and remarkably improve the mass transfer and chemical reaction rates. Consequently, the synergistic effects of the impinging streams and ultrasonic irradiation on the formation of mesoporous structure of FP nanoparticles have been systematically investigated through experimental validation and CFD simulation. The results revealed that the FP particles with a mesoporous structure can be well synthesised by precisely controlling the operation parameters by applying ultrasound irradiation with the input power in the range of 0–900 W and the impinging stream volumetric flow rate in the range of 17.15–257.22 mL·min−1. The findings obtained from the experimental observation and CFD modelling has clearly indicated that there exists a strong correlation between the particle size, morphology, and the local turbulence shear. The application of ultrasonic irradiation can effectively intensify the local turbulence shear in the reactor even at low Reynolds number based on the impinging stream diameter (Re < 2000), leading to an effective reduction in the particle size (from 273.48 to 56.1 nm) and an increase in the specific surface area (from 21.97 to 114.97 m2·g−1) of FP samples. The FP irregularly-shaped particles prepared by UTISR exhibited a mesoporous structure with a particle size of 56.10 nm, a specific surface area of 114.97 m2·g−1 and a total pore adsorption volume of 0.570 cm3·g−1 when the volumetric flow rate and ultrasound power are 85.74 mL·min−1 and 600 W, respectively. [ABSTRACT FROM AUTHOR]

• Twin-liquid film flow has been observed on a spoked rotating disk reactor. • Interplay between the confined free film and wall-bounded film leads to mass transfer intensification. • The circumferential length of the opening window should be accommodated to fluid viscosity. Spoked rotating disk reactor is a common gas–liquid mass transfer equipment for highly viscous fluids. The hydrodynamics of the twin-liquid film on the disk is numerically investigated. The simulated film thickness, which agrees well with the experimental results, shows that film flow patterns shift at different rotational speeds. The alternation between the windows and spokes brings diverse film flow pattern, i.e. , twin-liquid film, where a confined free film and a wall-bounded film coexist and interplay. The twin-liquid film results in 70% thinning of the film thickness and 30% increase in the surface renewal frequency compared to the wall-bounded film. Based on the trajectory of the tracking particles, intense velocity fluctuations within the twin-liquid film can be observed. Given the pressure gradient within the opening window increasing exponentially with fluid viscosity, we suggest that the circumferential length of the open window be proportional to fluid viscosity. The results demonstrate good adaptability of the optimization strategy, which can guide the scaling-up of the spoked rotating disk reactors for highly viscous fluids. [ABSTRACT FROM AUTHOR]