Modelling and simulation of a
microfluidic solvent extraction
process using a CFD software
M1 MASTER NUCLEAR ENERGY
29TH JUNE 2015
Student: Vera De la Cruz Gerardo
Supervisors: Siméon Cavadias, Clarisse Mariet and Gérard Cote
Referee: Eric Royer
PRESENTATION DISPLAY
I.
Global Objective
VI. Procedure
II. Extraction Process and
Microfluidics
VII. Difficulties and constraints
III. CFD Software
VIII.Flow Patterns tried
IV. Previous works
IX. Results
V. Assumptions-Modelling
X. Conclusions
| PAGE 2
GENERAL OBJECTIVE
Simulation of a solvent extraction process in a Y-Y shaped microfluidic device, using the COMSOL
Multiphysics software.
| PAGE 3
EXTRACTION PROCESS
• Industry
• Laboratories
Figure 1: Solvent extraction procedure with an additional Stripping step in the end.
Source: Solvent Extraction Cours notes, Pr. D. Pareau, Ecole Centrale Paris fall 2014.
| PAGE 4
WHY A MICROCHIP?
Microfluidics
 Small amounts of fluids (10−18 − 10−09 litres)
 Dimensions of tens to hundreds of micrometers.
Work with small volume
Better performance
with lower power
Ease of disposing of device
and fluids
Precise mixing/dosage
Can be integrated with
other devices – lab on a
chip
Minimize dead space,
void
volume
and
sample carryover
Reduce cost of reagents and
power consumption
High surface to volume ratio /
Low Reynolds number
| PAGE 5
CFD SOFTWARE
Worldwide
well-known
software in
the science
field
Constant
improvement
Features
Specific
websites
and blogs
Dynamic
interface
| PAGE 6
PREVIOUS RESEARCH WORKS
Research Cooperation Project
HDR
Clarisse Mariet
M1 Student
Sean Robertson
| PAGE 7
GEOMETRY AND ASSUMPTIONS USED
Constant all along
the microchannel
𝜌𝑎,𝑜 → 𝐷𝑒𝑛𝑠𝑖𝑡𝑦
𝜇𝑎,𝑜 → 𝐷𝑦𝑛𝑎𝑚𝑖𝑐 𝑣𝑖𝑠𝑐𝑜𝑠𝑖𝑡𝑦
𝜎 → 𝑆𝑢𝑟𝑓𝑎𝑐𝑒 𝑡𝑒𝑛𝑠𝑖𝑜𝑛
Defined for each one
of the phases
𝐷𝑈𝑟𝑎𝑛𝑖𝑢𝑚 →
Uranium diffusion
coefficient
𝐷𝐶𝑜𝑚𝑝𝑙𝑒𝑥 →
Complex diffusion
coefficient
| PAGE 8
COMPLEX FORMATION REACTION
𝑈𝑂2 𝐶𝑙
2−𝑛
𝑛
+ 𝑛 − 2 𝑅4 𝑁 + , 𝐶𝑙 − → 𝑅4 𝑁 +
for 𝑛 ≥ 3
𝑛−2 𝑈𝑂2
𝐶𝑙
2−𝑛
𝑛
+ 𝑛 − 2 𝐶𝑙 −
Simplification
𝜕𝐶
= 𝑘1 𝐴 − 0.1709𝐶
𝜕𝑡
A  Uranium concentration
C  Complex concentration
𝑘1  Mass transfer global
coefficient
Relation
𝑹𝑼𝒓𝒂𝒏𝒊𝒖𝒎 = −𝒌𝟏 𝑨 − 𝟎. 𝟏𝟕𝟎𝟗𝑪
Uranium reaction rate
𝑹𝑪𝒐𝒎𝒑𝒍𝒆𝒙 = 𝒌𝟏 𝑨 − 𝟎. 𝟏𝟕𝟎𝟗𝑪
Complex reaction rate |
PAGE 9
APPLICATION MODES
Fluid Flow
Laminar Two-Phase
Flow Level Set
Chemical Species
Transport
Transport of Diluted
Species
Physics
• Laminar Two-Phase Flow Level Set  Laminar flow
Moving interface
Immiscibility.
• Transport of diluted Species  Diluted species diffusion phenomena
Complexation reaction
| PAGE 10
STUDY STEPS
Steady state
| PAGE 11
HOW THE SOFTWARE WORKS?
The solutions obtained from the software are based on three pillars
1° Model
Equations
2° Treatment
of the
Interface
3° Boundary
conditions
setting
| PAGE 12
FIRST DIFFICULTIES
No convergence
Physical settings
Numerical stabilization
parameters
Table 1. Numerical stabilization parameters to be considered
Parameter
Symbol
Definition
𝛾
Reinitialization parameter
𝜖𝑙𝑠
Parameter controlling interface
thickness
Memory and time
Mesh optimization
| PAGE 13
MESH OPTIMIZATION
Conditions to take
into account
•
•
Immiscibility between the organic and the
aqueous phases
Strong kinetics present in the interface region
Sequence type: Physics-controlled mesh
Element size: Extremely coarse
Sequence type: Physics-controlled mesh
Element size: Fine
User-controlled mesh
| PAGE 14
SIMULATION MODELS – FLOW PATTERNS
Two basic flow patterns can be defined for all fluid systems
COUNTER CURRENT FLOW
CO-CURRENT FLOW
Dispersed Flow
Flow
rates
Continuous Co-current
Flow
Initial
fluid
Continuous
Counter-current Flow
Internal
Surface
and Fluids
properties
| PAGE 15
1) CO-CURRENT FLOW WITH MOVING
INTERFACE, LAMINAR FLOW
In a first trial the objective was to observe how the interface changed its appearance and to
obtain the required time for its stabilization.
| PAGE 16
1) CO-CURRENT FLOW WITH MOVING INTERFACE,
LAMINAR FLOW + CHEMICAL SPECIES
TRANSPORT
Stationary study after the flow stabilization and a time dependent study in parallel with the laminar flow
study.
| PAGE 17
2) COUNTER CURRENT FLOW
Interface instability
| PAGE 18
2) WETTABILITY AND CONTACT-ANGLE
This surface characteristic is defined by the surface wettability, characterized by the contact angle.
Figure 2: Contact angle, graphic definition.
| PAGE 19
3) CO-CURRENT DROPLET FORMATION
Phase initialization  Droplet Formation  Kinetics reaction in the interface
| PAGE 20
3) CO-CURRENT DROPLET FORMATION
The variations of the Uranium and the Complex concentrations can be observed in next
figures.
| PAGE 21
CONCLUSIONS
•
The software utilized in the simulations executed in this report is a very useful tool that allows the
users and researchers to obtain faster and cheaper results as compared to traditional
experiments.
•
The several scientific fields in which microfluidics are used allow the radiochemists to take advantage of
the innovations and the constant research carried out with regards to this kind of technology.
•
In previous works the phases interface had been considered fixed and the formation of droplets had not
been studied. The results obtained for this last case in this report permit analyzing the essential
characteristics of the extraction process in a microdevice for this flow pattern and are suitable to
be modified for different parameters values.
•
One of the next objectives in order to improve the yields of the microdevices is to calculate and
verify the relation between the inlet uranium concentration and the length necessary to extract it.
•
Although the surface hydrophobicity has been one of the topics more studied during the last years
because of its relevance concerning the microfluidics the software available to date is not able to consider
this aspect.
| PAGE 22
Thank you for your attention!
| PAGE 23