Bubble coalescence in electrolytes: effect of bubble approach velocity-

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985858%3A_____%2F21%3A00525219" target="_blank" >RIV/67985858:_____/21:00525219 - isvavai.cz</a>

Výsledek na webu

<a href="http://hdl.handle.net/11104/0311268" target="_blank" >http://hdl.handle.net/11104/0311268</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.cej.2020.125926" target="_blank" >10.1016/j.cej.2020.125926</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Bubble coalescence in electrolytes: effect of bubble approach velocity-

Popis výsledku v původním jazyce

The coalescence of air bubbles in aqueous solutions of electrolytes was studied experimentally. The bubbles were produced from two vertical parallel capillaries in a still liquid and video recorded. Several quantities were evaluated: bubble shape and size, bubble distance, bubble expansion rate, time of the first touch, time of bubble merger, time of bubble detachment. The three state variables were: bubble coalescence efficiency E, transition electrolyte concentration Ct, bubble contact time - coalescence time T. The effect of four control parameters was investigated: electrolyte type (3 inorganic salts: NaCl, Na2SO4, CaCl2), electrolyte concentration C (5 values sparsely covering a broad interval, 0.001 - 2 mol/L), bubble approach velocity V (9 values, from 0.03 to 40 mm/s), bubble diameter D (2 values, 1 and 1.5 mm). The following results were obtained. Coalescence efficiency E decreases with both C and V. Transition concentration Ct is not a material property but depends on the hydrodynamic conditions, Ct decreases with V. Contact time T decreases with V, as T ∼ V-1, and increases with C, roughly as T ∼ C1.9. Bubble approach velocity V plays a dual role: it reduces the coalescence region but accelerates the coalescence process. The transition from coalescence to noncoalescence proceeds via a minimum in the T(V) graphs. Bubble size D reduces the value of Ct, whence the extent of the coalescence region. The three electrolytes behave in a similar way. A scale-estimates model was developed to describe the results. The effect of electrolytes on the coalescence is similar to the effect of liquid viscosity.

Název v anglickém jazyce

Bubble coalescence in electrolytes: effect of bubble approach velocity-

Popis výsledku anglicky

The coalescence of air bubbles in aqueous solutions of electrolytes was studied experimentally. The bubbles were produced from two vertical parallel capillaries in a still liquid and video recorded. Several quantities were evaluated: bubble shape and size, bubble distance, bubble expansion rate, time of the first touch, time of bubble merger, time of bubble detachment. The three state variables were: bubble coalescence efficiency E, transition electrolyte concentration Ct, bubble contact time - coalescence time T. The effect of four control parameters was investigated: electrolyte type (3 inorganic salts: NaCl, Na2SO4, CaCl2), electrolyte concentration C (5 values sparsely covering a broad interval, 0.001 - 2 mol/L), bubble approach velocity V (9 values, from 0.03 to 40 mm/s), bubble diameter D (2 values, 1 and 1.5 mm). The following results were obtained. Coalescence efficiency E decreases with both C and V. Transition concentration Ct is not a material property but depends on the hydrodynamic conditions, Ct decreases with V. Contact time T decreases with V, as T ∼ V-1, and increases with C, roughly as T ∼ C1.9. Bubble approach velocity V plays a dual role: it reduces the coalescence region but accelerates the coalescence process. The transition from coalescence to noncoalescence proceeds via a minimum in the T(V) graphs. Bubble size D reduces the value of Ct, whence the extent of the coalescence region. The three electrolytes behave in a similar way. A scale-estimates model was developed to describe the results. The effect of electrolytes on the coalescence is similar to the effect of liquid viscosity.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

20402 - Chemical process engineering

Projekt

<a href="/cs/project/GA19-09518S" target="_blank" >GA19-09518S: Dynamika nestacionárních dějů v plyno-kapalinových soustavách</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2021

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Chemical Engineering Journal

ISSN

1385-8947

e-ISSN

1873-3212

Svazek periodika

460

Číslo periodika v rámci svazku

FEB 2021

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

18

Strana od-do

125926

Kód UT WoS článku

000603567400002

EID výsledku v databázi Scopus

2-s2.0-85090584841