Comparison of Hydrodynamic Cavitation Devices Based on Linear and Swirling Flows: Degradation of Dichloroaniline in Water

Abstract

Hydrodynamic cavitation (HC) is being increasingly used for a wide range of applications including wastewater treatment. No systematic comparison of pollutant degradation performance of different HC devices is available. In this work, for the first time: a basis for comparing performance of HC devices and a systematic comparison of pollutant degradation performance of five different types of HC devices based on linear and swirling flows is presented. 2,4-Dichloroaniline (DCA) was selected as a model pollutant in water as it contains multiple functional groups on an aromatic ring. Experiments were performed at two values of pressure drop across HC devices (100 and 200 kPa) at a constant initial concentration (35 ppm), pH (7), and temperature (18 °C) for five types of HC devices, namely orifice, venturi, orifice with swirl, venturi with swirl, and vortex diode. The pollutant degradation was interpreted by a per-pass degradation factor approach. The study demonstrated that five different types of cavitation devices performed similar to each other when these devices were designed to exhibit a similar pressure drop versus flow rate curve. It was conclusively shown that swirl does not suppress degradation performance while offering advantages on shielding device walls from collapsing cavities. This is an important and new result which will be useful for selecting and designing cavitation devices. Pollutant degradation data for geometrically similar vortex diodes of two smaller scales showed significantly higher degradation performance. The number of passes required for ∼10% degradation for the devices with a nominal capacity of 1, 5, and 20 LPM were 15, 100, and 1200 passes, respectively. The presented experimental data from these seven devices will be useful for evaluating computational models and hopefully stimulate further development of predictive computational models in this challenging area.

Removal of single and dual ring thiophene’s from dodecane using cavitation based processes

“…Additionally increasing the volume of the aqueous phase may hinder interfacial transfer of S and oxidising species. Similar data was reported by Bhasarkar et al [19] who investigated water addition in a H 2 O 2 /CH 3 COOH system for different pollutants and concentrations, reporting a slight decline in oxidation of BT, 3-methyl thiophene and thiophene at 100 ppm, 300 ppm and 500 ppm compared to the system without water. Therefore, only H 2 O 2 and carboxylic acid was utilised hence forth.…”

“…The HC device used in this work was a stainless steel vortex diode with throat diameter, d t = 6 mm purchased from Vivira Technologies. More details on the geometry and flow characteristics of this device may be found in Simpson and Ranade [18] , [19] . Details of experimental set-up and performance of HC device in terms of degradation of organic pollutants may be found in earlier work [19] .…”

“…More details on the geometry and flow characteristics of this device may be found in Simpson and Ranade [18] , [19] . Details of experimental set-up and performance of HC device in terms of degradation of organic pollutants may be found in earlier work [19] . The schematic of HC experimental set-up is shown in Fig.…”

Cavitation based cleaner technologies for biodiesel production and processing of hydrocarbon streams: A perspective on key fundamentals, missing process data and economic feasibility – A review

“…In contrast to linear flow cavitation devices, such as orifice and Venturi, swirling flow cavitating devices (e.g., vortex diode), proved to have early cavitation inception that starts at a pressure drop below 100 kPa [ 52 ]. Throughout the research, it has been found that in the case of linear flow cavitation devices, such as orifice and Venturi, cavitation takes place close to the device walls, causing the erosion of the device and lowering the device’s effectiveness over time, meanwhile in swirling flows devices, the cavitation takes place away from the walls of the device [ 53 ].…”

Valorizing Waste Biomass via Hydrodynamic Cavitation and Anaerobic Digestion

“…However, these are still comprised of small constrictions present in the device that makes a premilling step necessary for handling biomass or solids containing sludge. Linear flow devices have also been converted to swirl flow devices using inline swirlers , to lower cavitation inception pressure and mitigate cavitation erosion. The problem of clogging would however still persist because of the presence of small holes.…”