Oleg V. KozyukScientific archive

Research archive

Publication library

A searchable record of research, technical chapters, and process studies. Search titles and summaries, or follow the subject sequence through the archive.

Publication results

11 publications

  1. Flow constriction A conceptual fixed-geometry flow path with a focused low-pressure zone.

    Published

    Reactors & equipment

    Chapter 5. Hydrodynamic Cavitation Technological Equipment

    Hydrodynamic cavitation equipment is intentionally designed to create and then terminate low pressure regions in a liquid stream. This objective distinguishes process cavitators from pumps, valves, propellers, and hydraulic machinery in which cavitation is normally an unwanted cause of erosion, noise, vibration, and performance loss. In a process reactor, the pressure time history is selected so that bubble collapse, microjets, shock waves, interfacial renewal, and high local strain rates can be used for mixing, emulsification, cell disruption, extraction, oxidation, crystallization, heating, and other transformations [3-6,36].

  2. Flow constriction A conceptual fixed-geometry flow path with a focused low-pressure zone.

    Published

    Reactors & equipment

    Chapter 4. Cavitation in Hydraulic Machinery, Valves, Piping, and Marine Systems

    A centrifugal pump converts shaft work into fluid head through a rotating impeller and stationary casing or diffuser. The most familiar cavitation location is the impeller eye and blade leading edge, where relative velocity is high and pressure is low. Other forms occur in tip leakage vortices, balance passages, wear ring clearances, inlet recirculation, discharge recirculation, blade wake interactions, and diffuser or volute regions. These mechanisms have different operating point dependencies and therefore require different remedies [1], [2].

  3. Cavity cycle A conceptual sequence of pressure reduction, cavity growth, and pressure recovery.

    Published

    Fundamentals

    Chapter 3. Single Bubble Collapse Phenomena, Models, and Thermodynamic Effects

    Cavitation is the formation and subsequent dynamics of vapor filled or gas vapor cavities in a liquid when the local pressure becomes sufficiently low. A single cavitation bubble is the simplest experimentally accessible unit of this process. It can be produced by a focused laser pulse, an electric discharge, a rapid pressure reduction, a tensile acoustic pulse, or localized heating. Once the pressure recovers, the surrounding liquid accelerates inward and the bubble collapses. The bubble is called a cavitation bubble rather than an ordinary gas bubble because a substantial part of its volume is normally created by vaporization of the liquid, even though permanent gas and products of the generation process may also be present.

  4. Flow constriction A conceptual fixed-geometry flow path with a focused low-pressure zone.

    Published

    Reactors & equipment

    Anti-Cavitation Control Valves

    Control valves convert fluid pressure into irreversible losses so that a process variable can be regulated. In liquid service, the same energy conversion that makes control possible can produce a local pressure below the liquid vapor pressure. Vapor cavities then appear in the high velocity region and may collapse after the pressure recovers. The resulting microjets, shock waves, fluctuating forces, noise, and vibration can destroy trim, damage the pressure boundary, loosen instrumentation, and reduce usable valve capacity. Cavitation is therefore both a fluid mechanics problem and a reliability problem. [1-3, 13-15, 21]

  5. Process transfer A conceptual process route from feed through treatment to measured output.

    Published

    Industrial applications

    9. Hydrodynamic Cavitation in Pharmaceutical Particle Engineering, Crystallization, and Drug Delivery

    Pharmaceutical particle engineering does not simply aim to minimize particle size. Its practical objective is to produce a reproducible particle or vesicle population that is physically stable, manufacturable, compatible with the intended route of administration, and capable of delivering the required dose and release profile.

  6. Process transfer A conceptual process route from feed through treatment to measured output.

    Published

    Industrial applications

    13. Hydrodynamic Cavitation for Wastewater Processing

    Water processing now has to address contaminant classes that are not reliably removed by conventional clarification and biological treatment. These include refractory organics, pharmaceuticals, pesticides, dyes, solvents, pathogens, algal cells, viruses, and complex solids contained in waste activated sludge. Hydrodynamic cavitation (HC) is relevant because it can impose mechanical, thermal, and chemical effects in the same flow through device, commonly at near ambient bulk temperature and without requiring an optical path through the liquid [1-8].

  7. Process transfer A conceptual process route from feed through treatment to measured output.

    Published

    Industrial applications

    12. Food and Fermentation Processing

    Food and fermentation processing must satisfy several competing objectives at the same time. A successful operation controls microorganisms and enzymes while retaining flavor, color, nutrients, protein functionality, emulsion stability, and the required rheology. Conventional plants therefore combine mixers, mills, homogenizers, heat exchangers, deaerators, fermenters, separators, and holding tubes. Hydrodynamic cavitation provides a process intensification option because one compact flow device can generate pressure oscillation, cavity growth and collapse, localized shear, microjets, turbulence, interfacial renewal, gas dispersion, particle disruption, and viscous heating within the same circulation loop [1 to 8].

  8. Process transfer A conceptual process route from feed through treatment to measured output.

    Published

    Industrial applications

    11. Vegetable Oil Refining, Biodiesel, and Oleochemical Conversion

    Vegetable oils and fats are valuable mixtures whose dominant components are triacylglycerols, but whose processing behavior is governed by much smaller concentrations of phospholipids, free fatty acids, soaps, water, metals, pigments, oxidation products, waxes, partial glycerides, and suspended solids. Refining must remove selected impurities while retaining neutral oil, tocopherols, sterols, and other desirable minor components. Biodiesel production has a related objective: convert acyl groups to fatty acid alkyl esters while controlling glycerol, alcohol, catalyst, soap, metals, water, oxidation stability, and cold flow behavior. Oleochemical conversion expands the same chemistry to hydrolysis, esterification, interesterification, structured lipids, fatty acids, soaps, and glycerol based coproducts [6,7,8,9].

  9. Process transfer A conceptual process route from feed through treatment to measured output.

    Published

    Industrial applications

    Effect of Sodium Hydroxide Solution Droplet Size on Mass Transfer and Free Fatty Acid Neutralization in Vegetable Oil

    Chemical refining converts free fatty acids in vegetable oil into sodium soaps by contacting the oil with an aqueous sodium hydroxide solution. The acid base reaction is fast after the reactants meet. The observable rate is therefore governed mainly by interfacial area, oil film transfer, internal droplet transport, soap accumulation, and reactor hydraulics. Smaller droplets increase interfacial area and shorten the calculated residence time, but they also create a finer soap rich dispersion that is harder to separate. Industrial systems consequently benefit from staged hydrodynamics: intense dispersion for contact, controlled retention for completion, and gentle conditioning before centrifugal separation. [1, 2, 3, 16]

  10. Cavity cycle A conceptual sequence of pressure reduction, cavity growth, and pressure recovery.

    Published

    Fundamentals

    2. Physical Basis and Hydrodynamic Generation

    Cavitation is possible when the local pressure approaches the effective inception pressure. For a pure liquid with an ideal surface, this pressure could be below the equilibrium vapor pressure. Real process liquids contain microscopic nuclei, dissolved gas, particles, rough surfaces, and surfactants, so inception often occurs before the ideal tensile limit is reached. The vapor pressure pv(T) is therefore necessary but not sufficient for predicting inception. Temperature increases pv, while higher dissolved gas content generally increases the number of available nuclei.

  11. Cavity cycle A conceptual sequence of pressure reduction, cavity growth, and pressure recovery.

    Published

    Fundamentals

    1. Foundations, Definitions, Historical Development, and Generation Modes

    Cavitation is the creation of cavities in a liquid when local pressure becomes sufficiently low for vaporization or for preexisting gas nuclei to expand. A complete cavitation event includes nucleation, growth, convection, deformation, breakup, condensation, and collapse. The lowest pressure can occur at the eye or leading edge of a pump impeller, at a valve vena contracta, behind an orifice, in a leakage vortex, within a marine propeller tip vortex, or on the suction surface of a hydrofoil. The cavities may be isolated bubbles, an attached sheet, a coherent vortex core, or a shed cloud [1–3].