1. Lamella Mixer CHEM-E7160- FLUID FLOW IN PROCESS UNITS MOHAMMED REFAAT
JUSRI HASSANEIN
JAMA ALI

2. The context Introduction Modelling lamella mixer Relevant Equations
Results
Discussion/ Conclusion

3. Introduction Lamella mixing at microscale level
better selectivity, yield, process safety
computational fluid dynamics (CFD) can provide information about mixing efficiency and geometrical effects

4. Modelling lamella mixer
3 models where created using Google Sketch up and Autocad
all 3 models consisted of variating shaped chambers(triangular, rectangular and slit-shape) and constant size of microchannels with cross secton of 20 micrometer and 10 micrometer height
Two fluids with different of concentrations upper 100 mol/m^3 and lower 0 mol/m^3 enter the chambers through three and three small microchannels.
Pressure differences of the front end and back end is driving force.
Mixing of the the fluids will occur in the chamber

5. Lamella mixer with triangular chamber
Chamber length 100µm
and height 10 µm.

6. Lamella mixer with rectangular chamber
Chamber length 100 µm and
height 10 µm.

7. Lamella mixer with slit-shape chamber
Chamber length 100 µm and
height 10 µm (geometry
is divided at half of the
length).

8. Model description
The 3 models in comsol analyze the fluid flow in steady-state condition, diffusion and dissolved substance which is examined through concentration profile
Additionally, the effects of geometries , velocity, different mesh options and discretization methods on the concentration profile were examined
After running the models the mixing chambers were divided into 4 different locations to obtain the concentration profiles

9. Equations
The fluid flow in the channels and in the chambers can be solved with Navier-stokes equation(1)
The concentration the dissolved matter can be solved with convection-diffusion equation(2)
The micromixing that occurs in the chambers can be described with energy dissipation rate equation(3)

10. Results Velocity profiles
It can be seen the change in the velocity magnitude across the slices in each geometry and higher velocity occurred in the triangular.

11. Concentration distribution
At the entrance of the mixing chamber the concentration will gradually mix towards the end part of the chamber.
The mixing is more rapid at the edges of the chamber compared to the middle part due to the slow velocity.

12. Diffusion Coefficient
A slight change in the diffusion coefficient from 1E-10 m²/s to 1E-09 m²/s has a direct impact on the mixing efficiency.
Effect of the diffusion Coefficient from 1E-10 m²/s to 1E-09 m²/s.

13. The concentration distribution across chamber
4 cut lines was inserted in the center of the chamber followed by plotting the concentration profiles.
Effect on the concentration distribution by changing the diffusion coefficient from1E-10 m²/s to 1E-09 m²/s.

14. Discussion/ Conclusion
The mixing was achieved by using laminar layered flow in micro level scale.
The mixing chamber geometry was not critical in achieving effective mixing.
The diffusion coefficient value and the velocity range inside the model are the key factors to obtain effective mixing.
In order to enhance the mixing, longer mixing chamber is required, decrease flow velocity, and increase diffusion coefficient.

15. Any Questions?

16. Thank You!