Experimental investigation of the thermal and disinfection performances of a novel hydrodynamic cavitation reactor

Abstract

In the present study, we proposed an effective, efficient, and economical approach to disinfect water using a novel, advanced, rotational hydrodynamic cavitation reactor (HCR). First, analyses of the flow field and cavitation generation mechanism in the HCR were conducted through visualization of the reactor flow field using a high-speed camera. Second, the thermal performance was tested in 20 experiments with various rotational speeds of the rotor (2700, 3000, 3300, and 3600 rpm) and pump pressure settings (0.0, 0.5, 0.7, 1.0, and 1.5 bar gauge pressure). The HCR maximally achieved a heat generation rate of 48.15 MJ/h and thermal efficiency of 82.18%. Then, the disinfection effect was evaluated using water that simulated an effluent containing Escherichia coli (E. coli) for various flow rates (8, 11, and 14 L/min), a pump pressure setting fixed at 0.5 bar, and a rotational speed of 3600 rpm. In addition, an economical assessment of the disinfection processes was performed by considering the measured electric consumption. The thermal effect generated by the HCR was the dominant factor affecting the concentration of E. coli. The HCR achieved a 100% disinfection rate with a 4.3 L/min treatment rate and a cost of US $ 3.019/m at the optimal flow rate. The effects of the pressure setting and rotational speed on the performance were discussed in detail. Finally, compared to the recent studies, the treatment rate of the HCR is several hundred times greater than that obtained by the HCRs utilized in those studies, and also has a reasonable cost.

Plant and Biomass Extraction and Valorisation under Hydrodynamic Cavitation

“…The microorganisms rupture under shear forces with the powerful turbulence flow [57]. The treatment rate using this RSD is extremely higher and the cost is relatively reasonable compared with previous HCRs studies [51].…”

“…Moreover, they run into frequent clogging problems, resulting in profit loss, when treating solid-liquid mixtures. Rotary equipment and dynamic cavitational elements were developed with the aim of overcoming these problems and generating HC with less energy input [25,43,44,[50][51][52][53][54][55][56][57]. An example of this can be found in the rotor-stator device (RSD), which was developed by the University of Ljubljana.…”

“…Numerous cavitation bubbles and cavitation cloud separation (shedding) were clearly observed during the interaction between the rotor and stator. In such high-intensity separation regions, cavitation bubbles were produced as the pressures decreased under the saturated vapour pressure [51]. The microorganisms rupture under shear forces with the powerful turbulence flow [57].…”

Hydrodynamic Cavitation: A Promising Technology for Industrial-Scale Synthesis of Nanomaterials

“…When the bubble collapses, a huge amount of energy, on the order of 1-10 18 kW/m 3 , can be released into surrounding liquids (Gogate et al, 2006). The released energy can be divided into three forms (Sun et al, 2018b).…”

Novel Affordable, Reliable and Efficient Technologies to Help Addressing the Water-Energy-Food Nexus

“…In applications requiring working temperatures above the room level, such as in water disinfection and food pasteurization and sterilization, the heating efficiency can affect remarkably the process yields. HC processes showed excellent heating efficiency with a rotor-stator setup of the reactor (Sun et al, 2018). As well, all else being equal, the thermal efficiency was surprisingly higher when a closed loop pumping system comprised a Venturi-shaped HC reactor (Bermejo, Escaler, & Dular, 2018).…”