Multiphysical Environments and Systems

Multiphysical Environments and Systems Theme

Energy and climate constraints have only increased from year to year. In recent years there has been an increasing emphasis on reducing energy consumption and CO2 emissions by developing low-carbon and more energy-efficient solutions. The Multiphysical Environments and Systems Thematic Group (GT MPS) aims to respond to these economic and societal challenges by improving the efficiency of energy systems and processes. Our scientific approach is based on the identification, understanding and modelling of the multiphysical phenomena involved in thermal components, processes and energy systems with the aim of optimising, monitoring or even controlling them in a dynamic systemic environment. The research conducted on this theme covers two fields of expertise/science:

• “Multiphysical” phenomena: in particular, multiphase phenomena involving gas to liquid or liquid to solid phase changes. This thematic group integrates other multiphysical phenomena such as particle transport, reactive phenomena, coupling with solids mechanics and materials, and manufacturing processes into certain problems/applications.
• Multi-scale and systemic approaches: the group develops methods and digital models that integrate various scales ranging from the millimetric to the systemic scale. The phenomena specified in point 1) associated with the thermal components and processes studied are highly time-dependent and often occur in the absence of a so-called “established” regime. The development of reduced models often becomes a goal for the purpose of reducing computational costs while maintaining accurate physical predictions.

The target applications are sensitive or latent heat (involving phase-changes) storage systems and energy systems powered by renewable energies and waste heat recovery for industry or construction, with industrial processes that can integrate complex and multi-scale physics. Multiphase phenomena occur within heat exchangers or industrial processes such as liquid-vapour phase changes and the transport of particles which results in their fouling. Applications also involve the simulation of indoor air quality coupled with thermal comfort and the development of sensors taking into account fluid-surface interactions. These last themes are developed jointly with the Indoor Air Quality thematic group from the Atmospheric Sciences and Environmental Engineering (SAGE) team.

The scientific issues covered by the thematic group are primarily related to applications linked to all the techniques involved in increasing the energy efficiency of the system or component: Which storage or intensification technique could improve the control thermal inertia in the system or waste heat recovery unit? How can the overall performance of a process be improved along with its energy efficiency? What should the behaviour of the thermal component (locally optimised/intensified or otherwise) be like when integrated into an energy system to optimise the system’s operations and efficiency? How can active or passive-active intensification techniques (developed in the Fluidic Environments and Components – MFC – group) be optimised and controlled more intelligently based on the variable operating conditions of the system and its environment? Methodological issues are also studied. In order to propose multi-scale modelling strategies, it is necessary to develop appropriate modelling methods: With which approach should the modelling process start? Should we start with CFD approaches which require significant computational costs before transitioning to reduced models at a systemic scale and obtaining an optimised or intensified configuration? Or, conversely, is it better to start with global simulations and finish with intensification or optimisation on the premises? How can we optimise a system, component or process which operates dynamically? Which optimisation technique should be chosen for optimal results while maintaining reasonable computational costs? How can we develop a reduced model of the dynamic behaviour of a component or process and what representativeness/limitations should be used? How can we experimentally identify the physical determinants required for modelling?

The Multiphysical Environments and Systems (GT MPS) Group’s scientific strategy

To answer these questions, the research conducted by GT MPS relies on its dual digital and experimental skills, with the modelling process frequently incorporating experimental validation that can be spread over several TRL scales (from 3 to 7). The purchase of equipment is therefore particularly emphasised to develop the themes of the GPT MPS in order to validate the models, or through academic collaboration. The GT MPS is equipped with state-of-the-art experimental investigation equipment and scientific instrumentation. This instrumentation meets the dual objective of identifying the physical determinants of the models developed and validating these models. Its main objective is to develop a “building of the future” platform using an experimental house on a 1:1 scale. The group’s strategy also includes strengthening existing industrial partnerships and developing new collaboration with industrial partners of various sizes (ranging from SMEs to large companies) from the Hauts-de-France region or elsewhere in France. Academic collaborations are being developed regionally (JUNIA), nationally (IMT Atlantique) and internationally (UMONS, Belgium; ETS, Canada). The research is co-funded through responses to calls for thesis proposals for the region and ADEME in particular, as well as through the CIFRE thesis programme with industrial partners.