Physical Chemistry

Energy, momentum and mass transfer IIB

Introduction

In many biological and chemical processes, multiphase operation units are important parts of the process chain. Depending on the application, the aims are energy, momentum and/or mass transfer in the according unit. As in real processes, often a non-Newtonian continuous phase is apparent, the description of such systems is even more complicated. Nevertheless, even for Newtonian continuous phases, e.g., the deformation of fluidic particles (bubbles or drops) still leads to a demand in fundamental research.

Experimental investigations

At the Department, diverse research projects deal especially with the momentum and mass transfer in multiphase systems. This includes numerical and experimental investigations of the fluid dynamics of fluidic particles (bubbles and drops, in the following only called drops) with, i.a., questions regarding the the influence of the rheology on transport phenomena und the investigations of coalescence and breakage of drops within single drop or droplet swarm systems for the description with the help of population balance equations. In the field of mass transfer, diverse projects investigate, i.a., the influence of surfactants (tenside, salt, also nano particles) and rheology of the continuous phase.

These topics are investigated in the following projects while this list is not complete:

SPP1740 - Reactive Bubbly Flows

SPP1934 - DiSPBiotech - Dispersitäts-, Struktur- und Phasenänderungen von Proteinen und biologischen Agglomeraten in biotechnologischen Prozessen

SFB/TR63 - inPROMPT - Integrated Chemical Processes in Liquid Multiphase Systems

BMWi ERICAA - Energy and resource saving by innovative and CFD-based design of liquid/liquid-gravity-separators

AiF ZIM - SPI- Smart Process Inspection

and more

The used measurement techniques are, i.a., laser-based particle image velocimetey, high speed cameras und electrodiffusion method (EDM). The information gained with these techniques can be compared with CFD simulations. In the frame of the projects a close collaboration is established with, e.g., the Department of Civil Engineering of the University of British Columbia, Vancouver, Canada, and the Institute of Chemical Process Fundamentals of the Academy of Sciences of the Czech Republic.

Numerical investigations

Numerical investigations of multiphase systems are performed with the help of the software OpenFOAM. The fluid dynamics and the mass transfer of bubbles in non-Newtonian continuous phases are of particular interest.

In the past, the Computational Fluid Dynamic (CFD) Tool “Fluent” was used, as well, in combination with User Defined Functions (UDF). UDFs are subroutines written in “C++” which are implemented to reduce the calculation duration while improving the quality of the results at the same time.

Specific focus was, e.g., on the shear stress, the terminal rise velocity and the flow conditions.