Drop breakage in a single‐pass through vortex‐based cavitation device: Experiments and modeling

Abstract

Liquid-liquid emulsions are used in many sectors such as personal care, home care, and food products. There is an increasing need for developing compact and modular devices for producing emulsions with desired droplet size distribution (DSD). In this work, we have experimentally and computationally investigated an application of vortex-based hydrodynamic cavitation (HC) device for producing emulsions. The focus is on understanding drop breakage occurring in a single-pass through the considered HC device. The experiments were performed for generating oil-in-water emulsion containing 1%-20% rapeseed oil. The effect of pressure drop across the HC device in the range of 50-250 kPa on drop breakage was examined. DSD of emulsions produced through a single pass was measured using the focussed beam reflectance measurements. Comprehensive computational fluid dynamics (CFD) model based on the Eulerian approach was developed to simulate multiphase cavitating flow. Using the simulated flow, population balance model (PBM) with appropriate breakage kernels was solved to simulate droplet breakage in a vortex-based HC device. The device showed an excellent drop breakage efficiency (nearly 1% which is much higher than other commercial devices such as rotor-stators or sonolators) and was able to reduce mean drop size from 66 to ~15 μm in a single pass. The CFD and PBM models were able to simulate DSD. The presented models and results will be useful for researchers and engineers interested in developing compact devices for producing emulsions of desired DSD.

Emulsions Using a Vortex-Based Cavitation Device: Influence of Number of Passes, Pressure Drop, and Device Scale on Droplet Size Distributions

“…Overall, a proof of concept for employing these vortex-based HC devices for emulsions , was developed. We used focused beam reflectance measurement (FBRM) for determining the drop size distribution . Because of its inherent limitation, FBRM cannot measure droplet sizes smaller than 1 μm.…”

Critical Review on Hydrodynamic Cavitation as an Intensifying Homogenizing Technique for Oil-in-Water Emulsification: Theoretical Insight, Current Status, and Future Perspectives

“…Recently, Ranade and his group have reported using vortex-HC reactors for water disinfection, wastewater treatment, 46,48,49 desulphurization, 50 and emulsification. 30,31 As discussed above, high energy methods usually operate at high pressures (100−1000 bar), whereas low energy methods such as orifice and venturi devices usually require operating pressures in the range of 5−50 bar to achieve the desired cavitational yield and minimum droplet size of a nanoemulsion.…”

“…The desired cavitational intensity and homogenization efficiency can be achieved by varying the rotational velocity and residence time, which depend on the flow rate and operating pressure of the vortex system. Recently, Ranade and his group have reported using vortex-HC reactors for water disinfection, wastewater treatment, ,, desulphurization, and emulsification. , …”

“…Thaker and Ranade , recently used a low pressure vortex-based HC device to prepare emulsions. The main focus of their study was on the development of CFD and population balance models to study the droplet breakage in a single pass through this device.…”

“…To date, only a few studies have reported the use of LEHC for emulsification. − ,,− Although the HC technique has presented several advantages over conventional homogenizers, the impact of chemical effects of cavitation phenomena on emulsion’s physicochemical properties has often been overlooked. Therefore, this review aims to give an overview of hydrodynamic cavitation techniques used for emulsification, including the effects of HC on the physical stability of emulsion and the consequences of chemical effects on physicochemical properties of emulsions.…”