Investigation into cavitational intensity and COD reduction performance of the pinned disc reactor with various rotor-stator arrangements

Gostiša, Jurij; Zupanc, Mojca; Dular, Matevž; Širok, Brane; Levstek, Marjetka; Bizjan, Benjamin

doi:10.1016/j.ultsonch.2021.105669

Cited by 16 publications

(21 citation statements)

References 36 publications

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“…Advanced rotational HCRs (ARHCRs) that appeared recently (Figure 1C), where cavitation is induced by a high-speed rotating rotor, have demonstrated more superior performance in many applications, especially in food processing (1,15), compared with conventional devices. Several researchers have been devoted to demonstrating their mechanisms by experimental [flow visualization (19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29) and vibration (20,21,26,27) and thermal characteristics (19,23,28)] and numerical methods (30,31). Nevertheless, the research on this emerging type of device is relatively limited even though it has been commercialized nowadays.…”

Section: Principle Of Hydrodynamic Cavitationmentioning

confidence: 99%

RETRACTED: Hydrodynamic Cavitation: A Novel Non-Thermal Liquid Food Processing Technology

Sun

You

et al. 2022

Front. Nutr.

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Hydrodynamic cavitation (HC), as a novel non-thermal processing technology, has recently shown unique effects on the properties of various liquid foods. The extreme conditions of pressure at ~500 bar, local hotspots with ~5,000 K, and oxidation created by HC can help obtain characteristic products with high quality and special taste. Moreover, compared with other emerging non-thermal approaches, the feature of the HC phenomenon and its generation mechanism helps determine that HC is more suitable for industrial-scale processing. This mini-review summarizes the current knowledge of the recent advances in HC-based liquid food processing. The principle of HC is briefly introduced. The effectiveness of HC on the various physical (e.g., particle size, viscosity, temperature, and stability), chemical (nutrition loss), and biological characteristics (microorganism inactivation) of various liquid foods are evaluated. Finally, several recommendations for future research on the HC technique are provided.

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Section: Principle Of Hydrodynamic Cavitationmentioning

confidence: 99%

RETRACTED: Hydrodynamic Cavitation: A Novel Non-Thermal Liquid Food Processing Technology

Sun

You

et al. 2022

Front. Nutr.

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“…Based on the qualitative cavitation cloud dynamics comparison, similarities to the calculated results can be observed. Cavitation cloud dynamics was experimentally evaluated as shown in the work by Gostiša et al [ 10 ] The image was first rotated around the disc centre of rotation, and the cloud area was extracted from the image with an algorithm that includes mean background subtraction, pin masking, greyscale thresholding, and morphological closing. The overall trend of vapour fraction was found to be higher in the cases of 0.25 gap, 8 pin, and 12 pin compared to lower vapour fractions in the other two cases.…”

Section: Resultsmentioning

confidence: 99%

“…Based on the experimental observations on a pilot‐scale device [ 10 ] we focused our numerical study on the investigation of the dynamics of the interaction between the rotor and the stator (the gap between them) and the interaction among the rotor pins (the spacing between them)—the goal was to determine the details of the influences of the beforementioned parameters on the development of the cavitation cloud and the conditions in the cavitating zone. Since the focus of the interaction covers only a very small part of the device, a simplified 2D geometry was used for the simulations.…”

Section: Numerical Proceduresmentioning

confidence: 99%

“…This type of device was initially investigated on a pilot scale by Gostiša et al [ 9 , 10 ] where mechanisms of cavitation generation were experimentally determined by high‐speed visualization and pressure fluctuation measurements. Principally, cavitation was found to occur behind the element, presumably in the low‐pressure wake behind, and fluctuating vapour cloud dynamics was attributed to the passing rotor‐stator interaction.…”

Section: Rotating Generator Of Hydrodynamic Cavitationmentioning

confidence: 99%

“…We can generally divide them into (i) pumping and constriction reactors, [ 3 , 4 ] (ii) blow‐through reactors, [ 5 , 6 ] and (iii) rotor‐stator reactors. [ 7 , 8 , 9 , 10 ] Most of the advanced laboratory‐scale reactors are of the pump and constriction type, where the contaminated water (containing bacteria, viruses, algae, etc.) is forced by the pump through an orifice or venturi constriction where the sample cavitates.…”

Section: Introductionmentioning

confidence: 99%

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Computational analysis of flow conditions in hydrodynamic cavitation generator for water treatment processes

et al. 2022

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The research on the potential of cavitation exploitation is currently an extremely interesting topic. To reduce the costs and time of the cavitation reactor optimization, nowadays, experimental optimization is supplemented and even replaced using computational fluid dynamics (CFD). One of the approaches towards sustainable water treatment is the use of the cavitation reactor with bluff elements mounted on its stator and rotor. The experimental results show that, besides the rotational speed, the spacing of the rotor pins has the most significant effect on the cavitation intensity and effectiveness, while the pin diameter and the surface roughness are less significant design parameters. The present paper uses a simplified CFD approach to investigate the conditions in the reactor and to select the optimal among a number of geometry variations.

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Study on the characteristics of cavitation and COD removal of an addendum rotational hydrodynamic cavitation reactors

Zhou,

Luo,

et al. 2024

Asia-Pacific J Chem Eng

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This paper presented an addendum rotational hydrodynamic cavitation reactors (ARHCR) that enabled circumferential shear cavitation, axial cavitation, and the Venturi effect, thus increasing cavitation efficiency. The experiments on hydroxyl (·OH) release and chemical oxygen demand (COD) removal demonstrate the feasibility of cavitation performance characterization and COD removal rate. The findings indicate that the COD removal rate can reach a maximum value of 28% or 30% with an increase in flow rate or rotating speed, respectively. Specifically, the maximum values were achieved at a rotation speed of 2,500 rpm or a flow rate of 1.0 m3·h−1. Based on the mechanism of the addendum cavitation, the wedge angles, and the crucial structural parameters, were examined for optimizing cavitation performance. The results revealed that the cavitation number and cavitation bubble were significantly influenced by wedge angles, as well as the efficiency of cavitation energy. The mechanical shear of fluid was enhanced by wedge angles, resulting in constant compression and release of fluid with increased kinetic energy. This led to stronger effects on bulge blocks, and the formation of vortexes that rebounded constantly, resulting in lower pressure areas and expanded regions of cavitation. Among the wedge angles tested, the wedge angle of 15° exhibited the highest cavitation bubbles with a maximum value of 46%. This was 31% higher than the grooves‐type cavitator reported. Furthermore, the cavitation performance was extremely improved with a wedge angle of 15°, as corresponding with the maximum efficiency of cavitation energy. These explorations provide references for the removal of COD in industrial and agricultural wastewater, as well as the development of novel reactors for wastewater treatment.

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Investigation into cavitational intensity and COD reduction performance of the pinned disc reactor with various rotor-stator arrangements

Abstract: Graphical abstract

Cited by 16 publications

References 36 publications

RETRACTED: Hydrodynamic Cavitation: A Novel Non-Thermal Liquid Food Processing Technology

RETRACTED: Hydrodynamic Cavitation: A Novel Non-Thermal Liquid Food Processing Technology

Computational analysis of flow conditions in hydrodynamic cavitation generator for water treatment processes

Study on the characteristics of cavitation and COD removal of an addendum rotational hydrodynamic cavitation reactors

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