Iranian Journal of Chemical Engineering (IJChE)

Abstract  This study investigates the two-phase flow simulation in a Y-type  micromixer with a circular pit at the junction with a 1.7 MHz ultrasonic (US) transducer. A CFD simulation is conducted on the micromixer under varying fluid flow rates. Initially, the simulation is performed without US waves, and subsequently, the US waves are applied. The influence of US waves on flow behavior, mass transfer coefficient (KLa), and extraction efficiency (E) is assessed and contrasts with the same in the scenario where no ultrasound is applied. The simulation outcomes exhibit strong agreement with the experimental findings of a reliable reference. The findings indicate that the flow pattern for both aqueous and organic phases is parallel within the micromixer when ultrasound is absent.   However, applying the US waves alters the flow pattern and enhances the mixing. Under the US field, the interface between the two phases is completely disrupted and the contact between them increases. It is concluded that applying US waves into the liquid medium enhances turbulence, mixing, and the mass transfer rate inside the micromixer.  The influence of the flow rate of the aqueous phase at different US powers on KLa and E was investigated. The decreasing trend of KLa is observed. The effect of the power of ultrasound (P=3.5, 5.25, and 7W) on KLa and E is investigated and results show that P= 7 W has the more ability to enhance the mass transfer rate. The maximum error that is obtained for KLa is 5.43 %, which shows the high accuracy of the CFD model.

Abstract The Micromixing plays a key role in the most of industrial processes; enhancing its efficiency is a very important issue. In this study, a typical rotating packed bed (RPB) reactor equipped with the blade packing and high frequency ultrasonic transducers were designed to study the micromixing efficiency using the iodide/iodate reaction. The utilized ultrasonic transducers were ultrasonic atomizer humidifiers with the frequency of 1.7 MHz. Taking advantage of both the controllable high gravitational force and induced effects of the high frequency ultrasound, simultaneously, in a small volume reactor is the novelty of the present work. The effects of different parameters like the rotational speed, volumetric ratio, concentration of acid, ultrasonic power and number of activ transducers were investigated with and without the ultrasonic field. By increasing the rotational speed and volumetric flow, the segregation index decreased and by increasing the concentration of acid and volumetric ratio, the segregation index increased. In all of experiments, the segregation index decreased significantly under the ultrasonic field. Moreover, by increasing the ultrasonic power and number of active transducers the segregation index decreased. The obtained results indicated that the relative segregation index increased up to 41.1 % under the 1.7 MHz ultrasonic field. Therefore, the high frequency ultrasonic waves can intensify micromixing, even in a high efficiency equipment like RPB