Muphfince

Repository to store the codes used in research of MUltiPHase Flows IN Chemical Engineering (MuPhFInCE)


Project maintained by MartinIsoz Hosted on GitHub Pages — Theme by mattgraham

MuPhFInCE

Muffins ;-)

Repository to store the codes used by the MUltiPHase Flows IN Chemical Engineering (MuPhFInCE) research group of the University of Chemistry and Technology in Prague (UCT Prague).

The principal aim of the repository is to share the case settings and utilities between the group members. Our main tools are OpenFOAM, Paraview and Python.


Research motivation and background

Research motivation

Multiphase flow is of great importance in many chemical engineering applications. As examples, we may mention a description of hydrodynamics in absorption and distillation columns or bubble column reactors.

In our research, we focus mainly on the first of the listed processes. More specifically, we are aiming at modeling the flows with the utmost importance of the interfacial area size. Hence, the direct application of our work can be found in designing the above mentioned separation columns.

Background

A few notes on a structured packing and on a liquid flow on it.

Liquid flow on a structured packing

Water flow on a structured packing

Structured packing

Overall view of Mellapak 252Y packing Top view of Mellapak 252Y packing
Overall view of Mellapak 252Y packing Top view of Mellapak 252Y packing
Front view of a dismantled packing Top view of a dismantled packing
Front view of a dismantled packing Top view of a dismantled packing

Our approach to the problem

Separation columns, apparatuses used in chemical engineering to perform the mass transfer operations in large scales, host a complex set of physical processes including heat and mass transfer and multiphase flow. Even with the continuous development of computational fluid mechanics (CFD) methodology and the lasting growth of available computing power, the direct modeling of processes in packed columns is still an open issue. To develop a direct numerical simulation of a packed column, one would have to simultaneously solve the balance equations for momentum, mass, energy and the present species, all of which completed by a reliable model of mass and heat transfer across the interface. From a mathematics point of view, such a model would have to consist of (at least) six partial differential equations and several algebraic equations defined on a complex domain forced by the packing geometry.

Because of the aforementioned complexity, it is a common practice to study the processes occurring in packed columns on simplified surrogate models. One of the currently most common approaches is to reduce the geometrical complexity of the column packing and to approximate a small part of it by an inclined plate. Thus, the properties of interest (hydrodynamics, heat and mass transfer) are studied in a simple cuboid geometry.

Cooperations

As the nature of our work would suggest, we closely cooperate with the Mass transfer group of UCT Prague as well as with the CFD Laboratory of UCT Prague (cs).


General description of the studied problem

Droplet spreading

Motivation

The quality of the solution for spreading flows depends heavily on the accuracy of the description of the spreading. Hence a simple case of a liquid drop spreading on a horizontal substrate was taken as a benchmark situation and several different discretization schemes were thoroughly compared.

Results

Unphysical behavior of some discretization schemes

Droplet spreading

Parasitic currents in the solution

Droplet spreading

Relevant repository directories

Liquid flow down an inclined plate

As it was mentioned before, the most widely employed approximation of packing geometry is by an inclined plate. Such an approximation enables a study of the hydrodynamics of fluid flows in both macro- and microscopic regimes.

The presented codes are divided in three sections corresponding to the surface treatment of the inclined plate. The initial and benchmark simulations were performed for the case of a smooth plate. Later on, extensions for the cases of a plate equipped with a longitudinal, transversal or pyramidal texture were added.

Smooth plate

Mesh size optimization

Smooth plate - mesh size optimization

Resuls for different liquid flow rates

Different flow regimes on a smooth plate

Textured plate

Flow on different texture types

Flow on different texture types

Longitudinal texture

Transversal texture

Pyramidal texture

Wetted to total area ratios in dependence on the flow Weber number

Relevant repository directories

Liquid flow between two perforated plates

The column packings usually consist of perforated metal sheets. To examine the liquid behavior between such sheets a simulation of a flow between two perforated plates was performed.

Usually, it is assumed, that the liquid is flowing in a film flow regime both on the bottom and under the top plates. Hence, an emphasis was made to distinguish between the different flow regimes.

Overall transient simulation of a flow between two plates with uniform perforation

Uniform perforation - overview

Flow regimes distinction for a flow between two plates with zig-zag perforation

Zig-zag perforation - flow types distinction

Relevant repository directories