ANALYSIS AND CORRELATIONS OF DIMENSIONLESS NUMBERS RELEVANT TO ORIFICES’ CAVITATING FLOW

The aim of this work was to establish a general design basis for pilot-scale units to treat textile dyeing wastewater containing recalcitrant organic chemicals by hydrodynamic cavitation (HC) using orifices of various geometries. Relevant tabulated data available in the literature were analyzed and correlated to obtain universal relationships to this end. In spite of extensive effort, most of the obtained correlations were system-specific, which still can be used for design using their respective orifice geometries as demonstrated. However, one salient general relationship links the pipe’s dimensionless loss coefficient (KLP) to the pipe’s Reynolds number (ReP), encompassing all data under consideration, which may serve as an additional design option to optimize such units. The implication of this relationship is a lower upstream pressure (P1) value with an increase in pipe diameter while using the same specified orifice and achieving the same desired cavitation number (Cv). The ratio of P1 value in the larger pipe to its value in the smaller pipe is a function of the smaller pipe diameter (DS) to the larger pipe diameter (DL) ratio: (P1 in DL) / (P1 in DS) = (DS /DL)2.33. A lower P1 value will increase the cavitation yield by decreasing the expended energy, especially if the required number of passes is large. Additionally, the variation of the orifices’ hole loss coefficient (KLh) with the ratio of the holes area to the pipe cross-sectional area (Ah/Ap) for cavitating flow is compared with that for non-cavitating/incipient cavitation flow reported in the literature. ABSTRAK: Tujuan kajian ini diadakan bagi mereka bentuk dasar umum unit skala-pandu bagi merawat pewarnaan air buangan tekstil yang mengandungi kimia organik rekalsitran daripada peronggaan hidrodinamik (HC) menggunakan orifis pelbagai geometri. Data berjadual berkaitan yang ada dalam kajian lepas dianalisa dan dikaitkan bagi mendapatkan kaitan universal hingga akhir. Walaupun pelbagai usaha telah dijalankan, banyak kaitan didapati mengguna pakai sistem-tertentu, di mana boleh digunakan bagi mereka cipta menggunakan geometri orifis yang ditunjukkan. Walau bagaimanapun, bagi menghubung kait pekali langsung tanpa dimensi (KLP) kepada paip nombor Reynolds (ReP), meliputi semua data di bawah pertimbangan, di mana membantu pilihan rekaan tambahan bagi mengoptimum unit tersebut. Implikasi hubungan ini adalah nilai tekanan hulu sungai bawah (P1) dengan penambahan diameter paip dengan menggunakan orifis sama yang sebenar dan mendapati nombor peronggaan yang sama diingini (Cv). Nisbah nilai P1 dalam paip besar kepada nilai paip kecil adalah berkadaran pada nisbah diameter paip kecil (DS) kepada diameter paip besar (DL): (P1 dalam DL) / (P1 in DS) = (DS /DL)2.33.

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Assessment of Tandem Venturi on Enhancement of Cavitational Chemical Reaction

Journal of Fluids Engineering ◽

10.1115/1.3026731 ◽

2008 ◽

Vol 131 (1) ◽

Cited By ~ 5

Author(s):

Hoseyn Sayyaadi

Keyword(s):

Chemical Reaction ◽

Oxidation Process ◽

Flow Characteristics ◽

Chemical Oxidation ◽

Cavitation Number ◽

Cavitating Flow ◽

Hydrodynamic Cavitation ◽

Operating Pressure ◽

Local Pressures ◽

Second Category

The collapsing phenomenon of cavitation bubbles generates extremely high local pressures and temperatures that can be utilized for the chemical oxidation process. This process is carried out in cavitation reactors. A Venturi tube is one of the most common forms of hydrodynamic cavitation reactors, which is suitable for industrial scale applications. In this work, the hydraulic performance and efficiency in chemical reaction of a new form of hydrodynamic cavitation reactors, which is called “tandem Venturi,” were studied and compared with the conventional type of the single Venturi. The tandem Venturi is used for enhancement of the chemical reaction of hydrodynamic cavitating flow. The reaction enhancement is useful especially for the reaction of aqueous solutions not containing volatile organic compounds (VOCs). The operating pressure, inlet pressure, flow rate, and consequently the cavitation number were controlled and systematically varied for both single and tandem Venturis. Moreover, a specified amount of H2O2 was injected into the flow as required. The effects of operating pressure and the cavitation number on cavitating flow characteristics for single and tandem Venturis were experimentally observed and the results were compared. In addition, the performance of the tandem-Venturi reactor for degradation of non-VOC contaminants (2-chlorophenol) was studied. Its performance was compared with the performance of a conventional Venturi reactor. Two different categories were conducted for the experiments. In the first category, the effect of the net cavitating flow on degradation of non-VOC for the single and tandem Venturis was compared. In the second category, the effect of H2O2 injection into the cavitating flow on degradation of non-VOC (“cavitation-oxidation” process) was studied. The performance of the single and tandem Venturis for the cavitation-oxidation process was compared. Further investigation was performed to assess the advantage of utilizing the tandem Venturi from the viewpoint of efficiency of the oxidation process. The results of the energy efficiency were compared with the corresponding efficiency of the single Venturi. Finally, the relationship between the main parameters of cavitation reaction flow with the chemical performance was discussed.

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Treatment of real industrial-grade dye solutions and printing ink wastewater using a novel pilot-scale hydrodynamic cavitation reactor

Journal of Environmental Management ◽

10.1016/j.jenvman.2021.113301 ◽

2021 ◽

Vol 297 ◽

pp. 113301

Author(s):

Charikleia Zampeta ◽

Kleio Bertaki ◽

Irene-Eva Triantaphyllidou ◽

Zacharias Frontistis ◽

Dimitris V. Vayenas

Keyword(s):

Pilot Scale ◽

Hydrodynamic Cavitation ◽

Industrial Grade ◽

Printing Ink ◽

Dye Solutions

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PIV Analysis of Cavitating Flow Behind Square Multi-Orifice Plates

10.29007/fhdg ◽

2018 ◽

Cited By ~ 1

Author(s):

Zhiyong Dong ◽

Wenqian Zhao

Keyword(s):

Conventional Technique ◽

Disinfection Byproducts ◽

Cavitating Flow ◽

Water Disinfection ◽

Hydrodynamic Cavitation ◽

Pathogenic Microorganisms ◽

Turbulence Structures ◽

Image Velocimetry ◽

Piv Analysis ◽

Mutagenic Effects

Currently, in water supply engineering, the conventional technique of disinfection by chlorination is used to kill pathogenic microorganisms in raw water. However, chlorine reacts with organic compounds in water and generates disinfection byproducts (DBPs) such as trihalomethanes (THMs), haloacetic acids (HAAs) etc. These byproducts are of carcinogenic, teratogenic and mutagenic effects, which seriously threaten human health. Hydrodynamic cavitation is a novel technique of drinking water disinfection without DBPs. Turbulence structures of cavitating flow were observed by the Particle Image Velocimetry (PIV) technique in a self-developed hydrodynamic cavitation device due to square multi- orifice plates, including effects of orifice number and orifice layout on velocity distribution, turbulence intensity and Reynolds stress, which aimed at uncovering mechanism of killing pathogenic microorganisms by hydrodynamic cavitation.

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Effects of Thickened Excess Sludge Pre-Treatment Using Hydrodynamic Cavitation for Anaerobic Digestion

Energies ◽

10.3390/en13102483 ◽

2020 ◽

Vol 13 (10) ◽

pp. 2483 ◽

Cited By ~ 1

Author(s):

Agnieszka Garlicka ◽

Monika Zubrowska-Sudol ◽

Katarzyna Umiejewska ◽

Otton Roubinek ◽

Jacek Palige ◽

...

Keyword(s):

Methane Production ◽

Pilot Scale ◽

Hydrodynamic Cavitation ◽

Excess Sludge ◽

Maximum Increase ◽

Primary Sludge ◽

Sludge Flocs ◽

Pre Treatment ◽

Flocculation Process ◽

Different Levels

The main purpose of this study was the assessment of the possibility of increasing the production of biogas through the pre-treatment of thickened excess sludge (TES) by means of the hydrodynamic cavitation (HC) conducted at different levels of energy density (EL) i.e., 70, 140 and 210 kJ/L. The experiments were performed on a pilot scale, and a mixture of thickened primary sludge (TPS) and TES was used as digester feed. The results documented that an important parameter determining the possibility of obtaining an enhanced methane production is the value of energy input in the HC process. This parameter determines the changes occurring in sludge as a result of disintegration (i.e., sludge floc deagglomeration, lysis of cells, re-flocculation process and the related release of compounds susceptible to biodegradation from sludge flocs). The maximum increase in methane yield (MY) of 152% was obtained for EL = 140 kJ/L. In this case, HC mainly caused sludge floc deagglomeration. An increase in MY was also recorded when TES was subject to the disintegration process at EL = 210 kJ/L. However, it was 4.3 times lower than that observed for EL = 140 kJ/L. Pre-treatment of TES at EL = 70 kJ/L did not contribute to an increase in methane production.

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Novel pilot scale photocatalytic treatment of textile & dyeing industry wastewater to achieve process water quality and enabling zero liquid discharge

Journal of Water Process Engineering ◽

10.1016/j.jwpe.2019.100934 ◽

2019 ◽

Vol 32 ◽

pp. 100934 ◽

Cited By ~ 9

Author(s):

Nupur Bahadur ◽

Nipun Bhargava

Keyword(s):

Water Quality ◽

Pilot Scale ◽

Process Water ◽

Liquid Discharge ◽

Textile Dyeing ◽

Industry Wastewater

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Contraction/Expansion Effects in 90° Miter Bends in Rectangular Xurographic Microchannels

ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels, Volume 1 ◽

10.1115/icnmm2011-58148 ◽

2011 ◽

Cited By ~ 1

Author(s):

Lam Nguyen ◽

John Elsnab ◽

Tim Ameel

Keyword(s):

Reynolds Number ◽

Critical Reynolds Number ◽

Area Ratio ◽

Loss Coefficient ◽

Sidewall Roughness ◽

Cross Sectional ◽

Loss Coefficients ◽

Minor Losses ◽

High Reynolds ◽

Reported Data

Xurography is an inexpensive rapid prototyping technology for the development of microfluidic systems. Imprecision in the xurographic tape cutting process can result in undesired changes in channel dimensions near features that require a change in cutting direction, such as 90° miter bends. An experimental study of water flow in rectangular xurographic microchannels incorporating 90° miter bends with different channel widths in each leg is reported. A set of twelve microchannels, with channel depth approximately 105 micrometers and aspect ratio ranging from 0.071 to 0.435, were fabricated from double-sided adhesive Kapton® polyimide tape and two rectangular glass plates. The channels were reinforced with a mechanical clamping system, enabling high Reynolds number, Re, flows (up to Re = 3200) where Re was based upon hydraulic diameter and average velocity. Reported data include friction factor and critical Reynolds number for straight microchannels and loss coefficients for flow through 90° miter bends that contain either a contraction or expansion with cross-sectional area ratios of 0.5, 0.333 and 0.2. The critical Reynolds number, Recr, ranged from 1750 to 2300 and was found to be dependent on channel defects such as sidewall roughness, adhesive droplets, and corner imperfections. Loss coefficients through 90° miter bends with expansion decrease rapidly for Re < Recr. At the transition, the loss coefficient suddenly drops and approaches an asymptotic value for Re > Recr. For 90° miter bends with contractions, loss coefficients gradually decrease with increasing Re for 150 < Re < 1400. In addition, the loss coefficient decreases with decreasing area ratio through the contraction or expansion. The minor loss coefficient data were found to be dependent on Reynolds numbers and area ratio of contraction/expansion at the bend. The results suggest that the effect of the contraction/expansion was the dominant mechanism for minor losses in the 90° miter bend.

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Pilot scale intensification of rubber seed ( Hevea brasiliensis ) oil via chemical interesterification using hydrodynamic cavitation technology

Bioresource Technology ◽

10.1016/j.biortech.2017.03.046 ◽

2017 ◽

Vol 242 ◽

pp. 272-282 ◽

Cited By ~ 12

Author(s):

Awais Bokhari ◽

Suzana Yusup ◽

Lai Fatt Chuah ◽

Jiří Jaromír Klemeš ◽

Saira Asif ◽

...

Keyword(s):

Hevea Brasiliensis ◽

Pilot Scale ◽

Hydrodynamic Cavitation ◽

Chemical Interesterification ◽

Rubber Seed

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Influence of Orifice Shape on Reaction Rate by Hydrodynamic Cavitation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.625.718 ◽

2014 ◽

Vol 625 ◽

pp. 718-721 ◽

Cited By ~ 1

Author(s):

Keiji Yasuda ◽

Toa Kaji ◽

Zheng Xu

Keyword(s):

Reaction Rate ◽

Reaction Rates ◽

Hole Diameter ◽

Orifice Plate ◽

Hydrodynamic Cavitation ◽

Hole Area ◽

Upstream Pressure ◽

Shaped Hole

Hydrodynamic cavitation is expected to apply to the decomposition of chemicals and the disinfection in wastewater. In this study, the effects of upstream pressure, hole diameter and shape of orifice plate on the reaction rate of I3- formation were investigated. The reaction rate increases with increasing upstream pressure of orifice plate. The reaction rates have maximum values, when hole diameters of orifice plate are 2.7 mm at the upstream pressure of 0.9 MPa gauge and 3.0 mm at 0.7 MPa gauge. The reaction rate increases in the order of triangle < square < hexagon < circle shaped hole of orifice plate at the same hole area.

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