Cavitationally Driven Transformations: A Technique of Process Intensification

Abstract

The process intensification (PI) can significantly improve energy and process efficiency by enhancing mixing, mass, and heat transfer as well as driving forces. There are several benefits of such improvements, which include energy and cost savings, enhanced safety, smaller reactor size, less waste generation, and higher product quality. This review article focuses on the PI, discussion about its dimensions and structure, what it involves, and recent developments in PI which can be achieved using the technique of cavitation. Recommendations for optimum operating parameters needed for process intensification using cavitation phenomena which has been reported in the literature have been presented along with some of our own work in the area. Some experimental case studies have been presented which highlight the degree of intensification achieved when cavitation is used for different physicochemical transformations. These physicochemical transformations include crystallization, emulsification, extraction, wastewater treatment, depolymerization, and water disinfection.

Real-Scale Integral Valorization of Waste Orange Peel via Hydrodynamic Cavitation

“…Hydrodynamic cavitation (HC) is generally achieved via pumping a liquid through one or more constrictions of suitable geometry, such as Venturi tubes and orifice plates. Controlled HC results in the generation, growth, and collapse of microbubbles due to pressure variations in the liquid flow [18]. The increase in kinetic energy at the constriction occurs at the expense of pressure, leading to the generation of microbubbles and nanobubbles, which subsequently collapse under pressure recovery downstream of the constriction [19].…”

“…Again, the HC processing of vegetable raw materials, such as grains and hops for beer-brewing [30,31] or plant leaves [32], and its application to the extraction of bioactive compounds [27], offer distinct advantages, such as shorter process times, higher energy efficiency and yields, and enhanced extraction rates. When compared with both conventional techniques and newer ones, including acoustic cavitation sustained by ultrasound irradiation, the HC-based processes showed superior performance, due to enhanced process yields and straightforward scalability [18,33].…”

Real-Scale Integral Valorization of Waste Orange Peel via Hydrodynamic Cavitation

“…Generally achieved via pumping a liquid through one of more constrictions of suitable geometry, such as Venturi tubes and orifice plates, controlled hydrodynamic cavitation results in the generation, growth and collapse of microbubbles due to pressure variations in the liquid flow [20].…”

“…Again, the HC processing of vegetable raw material, such as grains and hops for beer-brewing [32,33], plant leaves [34], and applied to the extraction of bioactive compounds [29], offers distinctive advantages such as shorter process times, higher energy efficiency, higher yields, and enhanced extraction rates. Quantitatively compared with both conventional techniques and newer ones, including acoustic cavitation sustained by ultrasound irradiation, the performance of HC-based processes was found to be clearly superior due to enhanced process yields and straightforward scalability [20,35]. Such device was used in past studies to carry out innovative beer-brewing [32,33,36,37], for which application an industrial-level plant (2,000 L) was developed [38], the enhancement of biochar properties [39], and the solvent-free extraction of bioactive compounds, namely polyphenols and flavonoids, from the leaves of silver fir plants [34].…”

A novel rotation generator of hydrodynamic cavitation for the fibrillation of long conifer fibers in paper production

“…Ultrasonic cavitation has been proven to be an effective method but only for refining shorter fibers sources such as eucalyptus, wheat straw, bamboo, sugarcane bagasse, rice straw and corn stover [12,25]. Other generally known shortcomings of ultrasonic cavitation are high energy consumption, inability to treat larger volumes of water in a continuous mode and a difficult scaleup to industrial scale which has not yet been achieved [26,27].…”