Rapid Micromixing by the Impingement of Free, Paper-Thin Sheets of Liquids

 

Video is a front view of the impingement of two, equal paper-thin sheets of water impinging at a 45o angle to produce a mixed or combined sheet.  Single sheet thickness is about 80 microns at impingement and the impingement zone can clearly be seen as a thin arc segment line stretching across the fan shaped sheets.  Pressure drop is only 0.25 bar (3.6 psig) for a single sheet flow rate of about 1.1 liters/minute.

Impinging-Sheet Injectors

 

Impinging-sheet injectors provide millisecond mixing of liquids. The following photographs compare impinging-sheet injectors with impinging-jet injectors. The quality of the liquid-phase mixing is demonstrated by impinging sodium hydroxide containing phenol red indicator with a 20% stoichiometric excess of hydrochloric acid with no indicator. In base the phenol red is red in color while at an acidic pH (less than pH 7), the phenol red is yellow in color.

This photograph of an impinging-sheet injector shows that the droplets formed at the end of the mixed sheet are all  yellow in color.  In the mixed sheet the excess acid has neutralized the base causing the phenol red to convert to it’s yellow form.  Time from impingement to mixed sheet breakup is ~ 5 ms.  Operating conditions are single sheet flowrate of 1.9 liters/minute, sheet thickness at impingement of 80 microns, impingement distance of 2 cm, impingement angle of 45o and pressure drop of 0.69 bar (10 psig).

This photograph of an impinging-jet injector shows a central core of liquid in the formed sheet that is still red and has not been neutralized (despite the 20% excess acid).  Operating conditions are single jet flowrate of 1.9 liters/minute, jet diameter of 2 mm, impingement distance of 2 cm, impingement angle of 60o and pressure drop of 0.69 bar (10 psig). At impingement the thickness of the equivalent single sheets is only 80 microns (a factor of 25 times less).

This photograph shows two jets impinging upon one another where the impingement is very slightly off axis.  The liquid sheet formed by the slightly off-axis impingement is not visually affected.  However, the acid and base are now segregated in the liquid sheet resulting in poor liquid-phase mixing. Note that slight off-axis jet impingement is difficult to observe visually without the aid of an indicator (in this case a color indicator). Operating conditions are single jet flowrate of 1.9 liters/minute, jet diameter of 2 mm, impingement distance of 2 cm, impingement angle of 60o and pressure drop of 0.69 bar (10 psig).

Publications

Demyanovich, R.J., 2024, Experimental study and turbulence dissipative scale modelling of the rapid micromixing of impinging, paper-thin sheets of liquids. Chemical Engineering Research and Design 206, pp. 347-366. https://doi.org/10.1016/j.cherd.2024.04.060

Demyanovich, R.J., 2024, High energy dissipation rates from the impingement of free paper-thin sheets of liquids: Determination of the volume of the energy dissipation zone. Chemical Engineering Science 294,  120128. https://doi.org/10.1016/j.ces.2024.120128 https://doi.org/10.48550/arXiv.2403.08122

Demyanovich, R.J., 2021, High energy dissipation rates from the impingement of free paper-thin sheets of liquids: A study of the coefficient of restitution of the collision. Chemical Engineering Science: X  12:100113. https://doi.org/10.1016/j.cesx.2021.100113

Demyanovich, R.J., 2021, On the impingement of free, thin sheets of liquids – A photographic study of the impingement zone. AIP Adv. 11. https://doi.org/10.1063/5.0040336

Demyanovich, R.J., Bourne, J.R., 1992, Secondary mixing of Impinging Sheets. Chem. Eng. Commun. 113, pp. 133-146. https://doi.org/10.1080/00986449208936008

Demyanovich, R.J., Bourne, J.R., 1992, Impingement-sheet mixing of liquids at unequal flow rates. Chem. Eng. Process. 31, pp. 229-239. https://doi.org/10.1016/0255-2701(92)87015-9

Demyanovich, R.J., 1991, Production of commercial dyes via impingement-sheet mixing. Part II. Results of laboratory experiments. Chem. Eng. Process. 29, pp. 179-183. https://doi.org/10.1016/0255-2701(91)85018-J

Demyanovich, R.J., 1991, Production of commercial dyes via impingement-sheet mixing. Part I. Testing of a device suitable for industrial application. Chem. Eng. Process. 29, pp. 173-177. https://doi.org/10.1016/0255-2701(91)85017-I

Demyanovich, R.J., 1991, Absorption of carbon dioxide by impinging, thin liquid sheets. Chem. Eng. Commun. 103, pp. 151-166. https://doi.org/10.1080/00986449108910868

Demyanovich, R.J., Bourne, J.R., 1989, Rapid micromixing by the impingement of thin liquid sheets. 2. Mixing study. Ind. Eng. Chem. Res. 28, pp. 830-839. https://doi.org/10.1021/ie00090a027

Demyanovich, R.J., Bourne, J.R., 1989, Rapid micromixing by the impingement of thin liquid sheets. 1. A photographic study of the flow pattern. Ind. Eng. Chem. Res. 28, pp. 825-830. https://doi.org/10.1021/ie00090a026

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