Real‐Time Visualization of Internal and External Concentration Fields in Multiphase Systems via Laser‐induced Fluorescence and Rainbow Schlieren Deflectometry During and After Droplet Production

Jens Stefan Heine,Matthias Kraume,Joschka Marco Schulz,Hans‐Jörg Bart,Lutz Böhm,Henning Junne

doi:10.1002/cite.202000135

Abstract

AbstractThe applicability of laser‐induced dye fluorescence (LIF) and rainbow schlieren deflectometry (RSD) for qualitative, non‐invasive real‐time visualization of spatial concentration distributions in two standard reference systems is presented. The combination of LIF and RSD enables measurements inside and outside of droplets and is able to overcome limitations of both measurement techniques. Experimental results in the presence of interfacial phenomena are compared and the connection between inner and outer effects is shown during droplet production at a capillary.

Highlights

In many industrial processes, e.g., in chemical engineering, temperature and concentration gradients significantly affect the mass- and heat transfer rates
Each figure is comprised of rainbow schlieren deflectometry (RSD) results to transfer at both institutes are well established and have been the left and laser-induced dye fluorescence (LIF) results on the right side and shows exemintroduced in Heine and Bart [5] and Villwock et al [24]
The influence of the Marangoni effect on mass transfer at single droplets during and after droplet formation was studied with two independent methods: laser-induced fluorescence (LIF) measurements and Rainbow Schlieren

Summary

Introduction

E.g., in chemical engineering, temperature and concentration gradients significantly affect the mass- and heat transfer rates. Tioning of the dye limits the simultaneous accessibility of Schlieren imaging was used for visualization of different the internal and external concentration field as shown phenomena in the past, see, e.g. Settles [15] for an extensive exemplarily in Fig. 1 for the mass transfer of acetone from a overview of past applications and Settles and Hargather toluene drop into stagnant water as continuous phase. Though the advantage of a direct meacurvature of the surface of the drop, which leads to a strong surement of the transfer component is given there, usually displacement in the filter plane and no colorneither the temporal resolution nor the full-field nature are coded information can be measured inside of the drop as comparable to LIF or RSD [9]. The setup is a slightly modified version of the one introduced in

Laser-induced Fluorescence at TUK

Mass Transfer Test Cells for Optical and Suction

Conclusions