Recent Developments in Hydrodynamic Cavitation Reactors: Cavitation Mechanism, Reactor Design, and Applications

Hydrodynamic cavitation is considered to be a promising technology for process intensification, due to its high energy efficiency, cost-effective operation, ability to induce chemical reactions, and scale-up possibilities. In the past decade, advancements have been made in the fundamental understanding of hydrodynamic cavitation and its main variables, which provide a basis for applications of hydrodynamic cavitation in radical-induced chemical reaction processes. Here, we provide an extensive review of these research efforts, including the fundamentals of hydrodynamic cavitation, the design of cavitation reactors, cavitation-induced reaction enhancement, and relevant industrial applications. Two types of hydrodynamic cavitation reactors—namely, stationary and rotational—are compared. The design parameters of a hydrodynamic cavitation reactor and reactor performance at the laboratory and pilot scales are discussed, and recommendations are made regarding optimal operation and geometric conditions. The commercial cavitation reactors that are currently on the market are reviewed here for the first time. The unique features of hydrodynamic cavitation have been widely applied to various chemical reactions, such as oxidization reactions and wastewater treatment, and to physical processes, such as emulsion generation and component extraction. The roles of radicals and gas bubble implosion are also thoroughly discussed.