Taylorbubbles

Investigation of particle separation at a gas-liquid interface

The transport of micropollutants and their transition to a liquid, that is aerosol-to-liquid capture, is a widely used particle separation technique. One example is the cleaning of a gas, in which nano- and micro-pollutants are suspended. A simple and effective solution, called wet scrubbing, consists in injecting the contaminated gas in a dispersed form into a liquid reservoir. As individual gas bubbles rise, the suspended micro-pollutants bind to the liquid and hence separate. The aerosol separation from the gas is however complex because of the subtle dynamics interplay between the aerosol, gas and liquid transport.

Experimental investigation of Taylor bubble in narrow channels

To study particle separation, we propose to use Taylor bubbles as a replacement. In a vertical milli-channel, as is the case here, such bubbles do not need to be stabilized with surfactants, have a highly reproducible bullet shape up to ten centimeters in length and are ideal candidates for CFD validation.

Figure 1: Taylor bubble moving through in narrow channel with constriction for improved microparticle separation

Particle separation in rising Taylor bubbles

While gas flow plays a minor role in the molecular diffusion regime (for particles smaller than 0.1 µm), particle inertia becomes a dominant factor for larger particles, particularly in the 1.0–5.0 µm range. In this particle size range, inertia-driven impaction is the primary separation mechanism, making flow fields in both gas and liquid phases critically important. Particle separation rates in Taylor bubbles are measured in this specific regime. Various parameters are investigated, among other bubble length and channel constriction. This research has potential applications in aerosol filtration, gas-liquid mass transfer processes, and industrial separation technologies, contributing to advancements in environmental engineering, chemical processing, and microfluidic systems.

Funding

Supported by the German Research Foundation (Deutsche Forschungsgemeinschaft) under project number 459505672.

Publications

[1] Maestri, R., Büttner, L., Czarske, J., Hampel, U., Lecrivain, G.; Experimental investigation of aerosol separation in a rising Taylor bubble, Under Review

[2] Bürkle, F., Maestri, R., Hampel, U., Lecrivain, G., Czarske, J., Büttner, L.; Numerical and experimental flow fields on Taylor bubbles in constricted tubes, Experimental and Computational Multiphase Flow. Accepted (2025)

[3] Maestri, R., Radhakrishnakumar, S., Bürkle, F., Ding, W., Büttner, L., Czarske, J., Hampel, U., Lecrivain, G.; Equilibrium Taylor bubble in a narrow vertical tube with constriction, Physics of Fluids 36, 032108 (2024).