Numerical Multiphase assessment of geometric key parameters in Venturi-type reactor for process intensification

Hydrodynamics cavitation has the potential to significantly improve the efficiency and effectiveness of a wide range of industrial processes, including water treatment, chemical reactions, food processing, and biomass pretreatment. Cavitation can be used to replace traditional processing methods that are more energy-intensive or use harmful chemicals, which can help to increase the sustainability of industrial processes. Overall, using cavitation for process intensification can help improve efficiency, sustainability, and circularity in industry. One of the most used device that is easy to integrate with the production line is the cavitating Venturi reactor. In the present work, influence of the key geometric parameters such as the height and length of Venturi throat are evaluated to find the optimum reaction conditions enhancing cavitating treatment intensity and minimizing the pressure drop. The analysis has been conducted by varying the ratio of the throat section to the inlet section, keeping constant the cavitation number, to have cavitation dependent only on the geometry. A series of multiphase simulations have been performed using an open-source solver (OpenFOAM) that implements the Zwart-Gerber-Belamri cavitation model. The adopted modelling approach was the VOF (volume of fluid) mixture type coupled with the URANS (Unsteady Reynolds Averaged Navier Stokes) method, in which a komegaSST turbulence model has been applied. An FFT analysis was conducted to evaluate the cavitation regime. It was observed that by increasing the throat diameter, the frequency of the re-entrant jet mechanism decreases while the cavitation region extends. Finally the impact of pressure drop in various geometries was evaluated and compared with the CEP (cavitation efficiency parameter), a term developed to properly evaluate the efficiency of the cavitation phenomenon.