Multiscale analysis of gas absorption in liquids

Wylock, Dehaeck, Mikaelian, Larcy, Talbot, Colinet, HautTransfers, Interfaces and Processes (TIPs)

Université Libre de Bruxelles

TIPs department

Main objective of the research :

• Development of methods for the analysis of multiphase

systems, with the focus on transport phenomena

Scientific topics :

• Gas absorption in liquids, drying, evaporation, small scale

fluid physics (thin liquid film, contact line dynamics, …)

Outline of this presentationPresentation of 3 new theoretical, numerical and experimental

methods for the characterization of gas absorption in liquids

Characterization of the CO2 absorption in aqueous aminesolutions, in the frame of the development of capture processes

Our experimental tool : interferometry

CO2CO2

CO2

CO2CO2

HEP aqueoussolution

CO2

CO2

CO2CO2

CO2

Absorption of CO2 in HEP aqueous solution in a Hele-Shaw cell

CO2

Hele Shaw cell

Various HEP initial concentration

and Various inital amount of

CO2 absorbed

5

Gas

Liquid

Interface

LaserLaser

Polarizer

Polarizer

Spatial filter

Spatial filter

LensLens

Beam splitter

Beam splitter

Beam splitter

Beam splitter

Miror 2

Miror 2

Miror 1Miror 1

CameraCamera

Hele Shaw cell

Hele Shaw cell

6

LaserLaser CameraCamera

6

CO2

Time evolution of the refractive index

variation field in the Hele-Shaw cell

Contours of the refractive index variation field in the cell (n x 104)

CO2

HEP Solution

CO2

CO2

CO2

CO2

CO2

CO2

CO2

CO2

CO2

Refractive index variations can be related to loading variations

Loading (): (local) total amount of carbon moles (whathever the molecule it belongs

to) per unit volume of the solution

0

is identified by refractometry

Proposed model for the time evolution of the loading variation

field in the Hele Shaw cell

CO2 transfer rate between the gas and the liquid

max: max loading variation at the interfacek : interface saturation kinetic constant

D : pseudo diffusion coefficient describing the ability of the amine to move towards the interface

Model parameters identification by comparison with experiments

[HEP]0 = 1000 mol/m3

No initial loading

Outline of this presentationPresentation of 4 new theoretical, numerical and experimental

methods for the characterization of gas absorption in liquids

Characterization of the CO2 absorption in aqueous aminesolutions, in the frame of the development of capture processes

Development of a new experimental set up for the analysis ofthe dynamics and the morphology of bubbles rising in liquids

The experimental set up

de=2.5mm80 % water

– 20 % glycerol

No perspective effect !

Data obtained :

Precise mesure of the bubble volume

Field of view : 14 cm150 Hz

1024-1024 pixels2

Ellipsoidal bubbles with helical motion : frequency of the motion

f

A period of the helical motion is achieved when the bubble rise a

distance of approximately 10 times its diameter

Outline of this presentationPresentation of 4 new theoretical, numerical and experimental

methods for the characterization of gas absorption in liquids

Characterization of the CO2 absorption in aqueous aminesolutions, in the frame of the development of capture processes

Development of a new experimental set up for the analysis ofthe dynamics and the morphology of bubbles rising in liquids

Characterization of gas absorption into a spherical liquid droplet, in the frame of the development of flue gas cleaning processes

Transfer of a component A from a gas phase to a liquid droplet in free fall in this gas

Finite element resolution of dimensionless transport equations with COMSOL Multiphysics 3.4, in a reference frame attached

to the mass center of the droplet (Re < 250, low solubility)

Post processing :

Results

Results : low Re

Pure diffusion in a sphere :

Re = 0,1

Results : high Re

Re = 200

• Instantaneous saturation of a toroidal vortex periphery

• Diffusion inside this vortex

0.97 2.4

Conclusion

Presentation of 3 new methods for the characterization of gas absorption in liquids, at different scale

Focus given on the understanding of transport phenomena and their coupling

Based on analytical, numerical and experimental approaches

Many thanks for your attention!