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Wyszukujesz frazę "micro-cavitation" wg kryterium: Temat


Wyświetlanie 1-2 z 2
Tytuł:
Application of ultrasonic cleaning for shipborne heat exchangers: Construction, numerical simulation, and verification
Autorzy:
Buse, Hauke
Spangemacher, Lars
Fröhlich, Siegmund
Powiązania:
https://bibliotekanauki.pl/articles/24202542.pdf
Data publikacji:
2022
Wydawca:
Akademia Morska w Szczecinie. Wydawnictwo AMSz
Tematy:
ultrasonic
cleaning
heat exchanger
pipe bundle
micro-cavitation
simulation
Opis:
The current article describes the basics and prospects of the ultrasound-assisted cleaning of shell and tube heat exchangers that are used, e.g., on ships. A main issue of seawater heat exchangers is their clogging. After a certain operating time, the fouling process (barnacles, algae, etc.) starts, which results in a decreased performance that produces a noticeably reduced flow rate and a declining transmission of heat energy. Based on the current state of the art, heat exchangers are cleaned by mechanical or chemical (CIP, cleaning in place) methods. Especially on ship-based systems, a mechanical cleaning in very narrow spaces can be difficult and the usage of chemicals for CIP may generally be prohibited. An ultrasound-assisted cleaning would significantly save time and manning. Based on previous experiments, a test reactor represented by a shell and tube heat exchanger with ultrasound-assisted cleaning has been designed. A FEM (finite element method) simulation is performed to provide information about the ultrasound power distribution inside the reactor. Further, the assembly and commissioning of the test reactor with associated comparative measurements were carried out, which are also reported here.
Źródło:
Zeszyty Naukowe Akademii Morskiej w Szczecinie; 2022, 71 (143); 41--47
1733-8670
2392-0378
Pojawia się w:
Zeszyty Naukowe Akademii Morskiej w Szczecinie
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The non-unicity of the film thickness in the hydrodynamic lubrication: novel approach generating equivalent micro-grooves and roughness
Autorzy:
El Gadari, M.
Hajjam, M.
Powiązania:
https://bibliotekanauki.pl/articles/2106447.pdf
Data publikacji:
2021
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
równanie Reynoldsa
mikrotekstura
siła tarcia
siła nośna
Reynolds equation
inverse theory
micro-texture
cavitation
lifting force
friction force
flow rate
Opis:
Since the 1960s, all studies have assumed that a film thickness “h” provides a unique pressure field “p” by resolving the Reynolds equation. However, it is relevant to investigate the film thickness unicity under a given hydrodynamic pressure within the inverse theory. This paper presents a new approach to deduce from an initial film thickness a widespread number of thicknesses providing the same hydrodynamic pressure under a specific condition of gradient pressure. For this purpose, three steps were presented: 1) computing the hydrodynamic pressure from an initial film thickness by resolving the Reynolds equation with Gümbel’s cavitation model, 2) using a new algorithm to generate a second film thickness, 3) comparing and validating the hydrodynamic pressure produced by both thicknesses with the modified Reynolds equation. Throughout three surface finishes: the macro-shaped, micro-textured, and rough surfaces, it has been demonstrated that under a specific hydrodynamic pressure gradient, several film thicknesses could generate the same pressure field with a slight difference by considering cavitation. Besides, this paper confirms also that with different ratios of the averaged film thickness to the root mean square (RMS) similar hydrodynamic pressure could be generated, thereby the deficiency of this ratio to define the lubrication regime as commonly known from Patir and Cheng theory.
Źródło:
International Journal of Applied Mechanics and Engineering; 2021, 26, 3; 44--61
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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