Multi-scale Multi-phase Phenomena in Complex Fluids for Energy Industries – MUSCOFI

At the molecular level, the explicit description of electronic structures will be introduced using an approximated DFT model to retreive the structural, energetic, and thermodynamic data. We aim at developing a computational procedure to predict the impact of thermodynamic and physico-chemical parameters on the formation and structuration of water/solvent interfaces (asphaltenes and hydrates).
At the meso scale, the dynamic and structuration of water/oil interfacial films and their relation with the stability of emulsions will be studied. Our objective is to determine how the kinetics of nucleation and the hydrate crystal morphology are affected by physico-chemical parameters, and specifically, by the presence of surfactantsat the droplet interface. Then, by coupling micro fluidic chips with scattering techniques the structure of the solution before the nucleation and the structure of crystals after the nucleation will be characterized. The extrapolation from molecular, micro- and meso-scopic to the macroscopic scale will be validated by studying the influence of the global composition of systems and the presence of selected additives on the flow behavior, the dynamic of phase changes and mass and heat transfers. Macroscopic models will then be developed in an integrative approach which will include scalking laws for the smaller scales.

Contact angles have been measured between a CP hydrate crystal and various liquids, and the resulting surface energies have been published. A complete phase diagram has been published for the systems H2O – CP – CO2 between 0 and 4.3 MPa, as well as the composition, dissociation enthalpy and heat capacity of mixed hydrates. The high latent heat presented by this phase change material has promising application potential in the refrigeration sector.
The CP and CP + CO2 hydrate slurries have been characterized in a flow loop. The rheological properties of the slurry have been measured for CP fractions between 3 and 15 wt%. The fluids has a newtonian behavior at low CP fraction and shear thinning at 15 wt%. The apparent viscosity of CP hydrate slurries is greater than that of CP + CO2 hydrate slurries, showing a positive effect of CO2 on the reduction of viscosity.
In order to observe the crystallization of CP hydrates at nm to µm scales, a microscopic visualization tool has been fitted on a calorimetric cell. The hydrate crystallization has been followed in situ as a function of the scanning rate and the the number of cooling/heating cycles. It has been demonstrated that the hydrate forms close to the ice melting point, immediately after the release of free water, contrary to other model hydrates.
Concerning the molecular modeling, methodologic developments have been performed in order to improve the description of the water potential at the SCC-DFTB level.

The applicative potential of mixed hydrates has to be confirmed by the study of flow behavior, and by experimental and modeling results on the
crystallization/melting mechanisms and phase interactions at the molecular and mesoscopic scales. A study of the rheology of mixed CP + CO2 hydrate slurries in a rotating rheometer has just started. Measurements at different hydrate fractions will be undertaken in order to understand the relationship between the CP concentration and the quantity of produced crystals. Finally, the thermal properties of the flowing and steady slurries will also be investigated.
A microfluidic setup is currently being constructed for the observation of the formation of hydrates from a structural point of view by Raman/X-ray/neutron scattering techniques.
Simulations will be realized to validate the established potential of water on hydrates (CO2 and CP), for which radial distribution calculations have already been realized using a SCC-DFTB potential.

F. Thomas, D. Dalmazzone, J.F. Morris. Chem. Eng. Sci. 229 (2021) 116022. /10.1016/j.ces.2020.116022

N. Chami, S. Bendjenni, P. Clain, V. Osswald, A. Delahaye, L. Fournaison, D. Dalmazzone. Chem. Eng. Sci. 244 (2021) 116790. /10.1016/j.ces.2021.116790

J. Cuny, J. C. Calatayud, N. Ansari, A. A. Assanali, M. Rapacioli, A. Simon. J. Phys. Chem. B, 124 (2020) 34, 7421-7432. /10.1021/acs.jpcb.0c04167, hal-02959734t

R. Ramamoorthy, “ISIC 21 - 21st International Symposium on Industrial Crystallization” – Online event (Germany)

The behavior of complex multiphase fluids involved in various industrial fields is in large part governed by multi-scale phenomena, coupling interactions at the molecular, meso- and macroscopic scales. Those couplings are still poorly understood and require substantial development in experimental and theoretical knowledge, in order to achieve scientific discoveries that will be transferable to technological applications. Several applications related to energy industries are expected to benefit improvements from molecular and interfacial control of transport phenomena. More generally, any process concerned by the management of complex multiphase fluids and where the mass and heat transfers hindrance causes efficiency loss, will take advantage of extended understanding of multi-scale coupling phenomena.
The MUSCOFI project aims at interpreting macroscopic data and predicting macroscopic behaviour by using modelling and experimental tools to elucidate molecular-level phenomena that 1) govern the formation, aggregation, and stability of interfacial and network structures in multi-phase fluids, 2) control their development and effects on macroscopic rheology and transport processes, 3) and finally impact the efficiency of processes in energy technologies. It is a unique opportunity to federate complementary research teams in a new collaborative scheme that will cover the whole scale range, from the molecule to the industrial process.
The MUSCOFI project gathers the French partners of an international PIRE project (US NFS program "Partnerships for International Research and Education"), leaded by the City College of New York and that includes 12 research teams from the USA, Germany, Norway, and France. This program includes scientific collaborations, researchers and students exchanges, and symposia organization, on multi-scale investigation of complex fluids of interest to the energy sector. MUSCOFI will thus benefit from synergies at an international level in terms of cooperation, networking and international visibility. The students (2 PhD) and research fellows (2 x 18 months PostDoc) who will be hired during the project will benefit opportunities to spend internships in the partner laboratories abroad, while foreign students will be hosted in the French labs involved.
Two systems of particular interest in the field of energy will be investigated within this project: asphaltenes at water/oil interface, and clathrate hydrates in water/oil emulsion. These systems appear in diverse energy applications in oil & gas, heat storage, and environmentally friendly refrigeration.
The Tasks of the project are described bellow:
1 The model systems that will be investigated at the different scale levels, as well as the required operating conditions will be validated at the early stage of the project.
2 At the molecular level, the explicit description of the electronic structure will be introduced using an approximate Density Functional based Tight Binding method to retrieve structural, energetic and thermodynamic data.
3 Interactions at the liquid/liquid interfaces in the conditions of solid phase formation will be investigated using microfluidic experiments.
4 The extrapolation of molecular, micro- and meso-scopic results to the macroscopic level will be validated by measuring the influence of the global composition of the systems and the presence of selected additives on flow behaviors, phase change dynamics, and heat and mass transfers.
5 Models will then be developed in an integration and extrapolation approach that will include the local-scale findings to provide macroscopic predictive tools.
The project should produce abundent experimental and theoretical new results, promote the development of original methodologies, and offer opportunities for new national and international cooperations. In addition to academic publications, possible patent filling and future industrial partnerships could be valuable outpus of the project.