Interfacial rheology is key to control the stability of multiphasic assemblies like foams or emulsions as it governs the local interfacial flows between the plateau borders and the thin films. The stability and the foam behavior under drainage for example depend on both elastic and surface viscous moduli. Interfacial rheology also plays a major role in the rheology of suspensions of deformable particles of living fluids like blood. Indeed, the interactions between Red Blood Cells are governed by the mechanical response to the hydrodynamic flow which results from many-body interactions. The shear membrane viscosity has an essential contribution. In many applications in painting or in bioengineering such as encapsulation, self-healing is a sought property to ensure a sufficient life-time of interfaces, much like macromolecular re-assembly, which has its signature in the viscoelastic moduli and the constitutive law governing interfacial rheology. Unfortunately, intrinsic difficulties to measure these properties is blocking progress. This difficulty comes from the quasi-impossibility to quantify independently each parameter as shear and dilatational strains are often concomitant. A good agreement between the different techniques available is only found for scarce cases of surfactants. In the case of microcapsules and their thin biopolymer membranes, the dilatational viscosity and elasticity are nearly always ignored. Gathering a multidisciplinary consortium of three laboratories in physical-chemistry / soft matter (LPS), rheology / fluid mechanics (LRP) and High Performance Computing / mechanics (M2P2), 2DVISC will develop a versatile toolbox to measure the viscoelastic moduli characterizing the interfacial rheology of bubbles, droplets and microcapsules. It means the surface tension, the Marangoni modulus and both shear and dilatational surface viscosities in the case of bubbles and droplets and the shear and dilatational surface elastic moduli and both surface viscosities in the case of microcapsules. The principle is not to control purely shear or dilatational strains (or deformations) but to apply different simple linear flows, each one being characterized by two known components of shear and elongation rates to deform bubbles, droplets and microcapsules using (milli-)microfluidic tools. The overall deformation, orientation and the associated characteristic times depend on the viscoelastic moduli. A careful comparison of the dynamics of deformation and orientation with theoretical expressions determined in the limit of quasi-spherical shapes and advanced numerical models in the linear and nonlinear regimes allow to extract the interfacial surface moduli by inverse analysis. Several flow configurations will be investigated to demonstrate the self-consistency of the method. These parameters will be compared to standard independent measurements to validate the method. Finally, in the case of droplets and microcapsules, the method will be integrated in the microfluidic Four-Roll Mill to provide a unique toolbox. Full interfacial characterization will become possible using a single device.

ECOSAFE project is focused on the control and safety issues raised by massive implementation of alternative fuel like hydrogen, especially in confined systems such as internal geometry of fuel cell stack. Understanding the conditions for propagation of a flame in such slender geometries requires the systematic study of the coupling processes between the flame shape, the flow, the thermal dissipation at the walls and the acoustics. For that purpose, laboratory experiments will be performed but pose a tremendous challenge in terms of visualizations. Complementary numerical simulations using an novel Reactive Lattice-Boltzmann Model will be a determining step for the project.

The D2LIFE project aims to understand the interactions between organic matter and phosphates during the hydrothermal liquefaction of residual biomass (e.g. digestate, sewage sludge, manure, agro-waste). This knowledge will contribute to the development of a hydrothermal treatment process that integrates the recovery of phosphorus (P) with the production of bio-fuels, by concentrating P in a solid phase mainly composed of Ca phosphates which will be used as fertilizer. The objective of the project is to identify and describe the effect of the main operating parameters of the hydrothermal process (e.g. temperature, pressure, reaction time, addition of reagents) on the kinetics and pathways of P conversion, and on the partition of P among the aqueous, oily and solid phases resulting from biomass liquefaction. The methodological approach of the project is based on hydrothermal liquefaction experiments carried out in a batch reactor using a real substrate (digestate from anaerobic digestion of sewage sludge), followed by modeling of the experimental results. The aqueous, oily and solid phases resulting from digestate liquefaction will be separated and characterized in order to quantify the main forms of P (organic and inorganic). The results will allow to identify the effect of the main operating parameters of the hydrothermal process on the conversion pathways and on the partition of P among the different phases, and finally to develop a model that describes P conversion during hydrothermal liquefaction of digestate. Finally, a techno-economic analysis of the process will be carried out to identify the optimal operating parameters based on exergetic criteria, conversion yields, and by-products (Ca phosphates and bio-fuels) recovery performance. The results of the D2LIFE project will have an impact in the field of bio-waste and residual biomass management, and will contribute to the development of a sustainable process chain for the valorization of digestate.

NACREE finds origin in the observation that, surprisingly, there are no methodologies that allow the knowledge of the creation of irreversibility to be linked to the design of devices. This project aims to offer one. The methodology developed during the project will be applied to plug flow reactors in laminar regime. A direct exchanger system will be associated with the reactors. We will call hereinafter Reactive Converters (CR) the assembly formed by the reactor and the associated exchangers. NACREE aims to improve the match between sources and uses by proposing a method for designing and integrating CR based on entropy minimization. More exactly, it is a question of reducing the irreversibilities (i.e. the production of entropy) by an adapted writing of the source terms and to ensure the equipartition of these terms along the CR. The project's hypothesis is that this equipartition can be largely achieved by making the geometric design parameters of the reactor and the exchangers variable in space, as for example, for a cylindrical reactor, the evolution of the diameter along the axis. For this project, the potential gains from entropy reduction will be based on the study of the modification of the characteristic lengths of the reactor, local load of the catalyst, injection points of reagents, point of injection and withdrawal of utilities. These modifications aim at a triple reduction: that of the heating (or cooling) means, that of the pumping means and of the reagents used. The formulation of the entropy equipartition applied to a reactive system will first be reformulated in order to take these parameters into account. This formulation will be integrated into the modeling of the reactor. When modeling the reactor, it is necessary to have a detailed knowledge of the local exchange coefficients. As the geometries explored (both in the reactor and in the exchanger) are neither constant nor standard, NACREE requires recourse to computational fluid dynamics to calculate these coefficients in order to take into account the impact of geometric variations on the flows. From the simulations considered as numerical experiments, we wish to establish a set of empirical correlations allowing the rapid calculation of the exchange coefficients. These correlations will be used in the CR model. This optimization will be carried out using a single "objective" function which will be the creation of irreversibility according to the geometric parameters studied. This "objective" function will be the sum not of the results of the irreversibilities of the reactor alone but of all of the irreversibilities of the CR. The response surfaces method will be used as a robust and proven method of optimization because it results in the expression of a function that is easy to optimize. A key point of this project is validation by experience. The use of a model and controlled experience will validate the approach. For this, the choice of the consortium is oriented towards additive manufacturing in order to access precise realization of the calculated dimensions. Finally, in order to validate the approach and verify that the solutions proposed by the optimization are realistic, the energy integration of the utilities will be carried out under the constraint of the geometries studied. The purpose of this integration is twofold. Validate that the equipartition converges the system towards the Minimum Energy Required and establish a number of constraints that can be used in the model to constrain the parameters. Through this project we therefore wish to provide the bases for a general methodology for the design of reactors involving coupled transfers in order to obtain significant savings on primary energies and on reagents

The replacement of fossil fuels by renewable energies is probably one of the biggest challenges of the 21st century. Among the different energies, hydrogen is one of the most promising. The new concepts for the production of "renewable H2" are extremely promising (but still far from economic viability) and require fundamental research to understand and then optimize these processes. Produce and use renewable H2 can lead to innovative processes responding to societal, environmental and scientific interests. To date most of the works on the H2 production, via a biological pathway, focus on pure or genetically modified cultures, and the use of simple substrates. More recently, the use of microbial mixed cultures has emerged with regard to their robustness, the wide panel of usable substrates, their metabolic adaptability and flexibility. A new idea is that, more than their intrinsic properties, there are the interactions between microorganisms that confer a specific behaviour and resistance properties to a bacterial community. To date, very few studies integrate the role and the control of these interactions and none is coupled with a feasibility study of the use of biogas formed. This decoupling is partly the result of a very disciplinary approach. The EPI-H2 project aims to decipher and model the process leading to H2 production by integrating the functioning of individual cells and their interactions in mixed culture during a process, in order to validate the change of scale by integrating the feasibility of using the biogas produced. It is an interdisciplinary and innovative fundamental research project, with a continuum of studies ranging from integrated molecular metabolism to process scale, to propose an effective strategy for the development of a process that can eventually be valued for the production of renewable H2. It therefore requires to take advantage, in an integrated manner, several types of expertise and know-how: microbiology, metabolism, chemistry, modelling, process engineering in order to remove the scientific obstacles that limit the development and use of biotechnology. The project therefore aims to (i) decipher the bacterial communication within a synthetic consortium, (ii) estimate the impact of this one on the metabolism of the consortium's bacteria, in particular on the H2 production through a metabolic modelling approach that integrates experimental data from kinetic, metabolic and transcriptomic monitoring; (iii) evaluate the impact of scaling up on H2 production by a continuous process; and iv) validate the supply of an enzymatic fuel cell with the H2 produced, not purified. By integrating all fundamental knowledge, the ambition is to propose relevant parameters to contribute to the change of scale of the process, an essential step in the development of medium / long term applications.