Mesr - transition de phase et phénomènes de transports dans des composites à base de mcp organiques pour le stockage thermique de l'énergie // mesr - phase change behavior and transport phenomena in organic pcm-based composites for thermal energy storage

Topic description

Atteindre la neutralité carbone nécessite des solutions efficaces de stockage d'énergie, notamment pour les procédés thermiques (>50 % de la consommation mondiale). Parmi les solutions, les systèmes de stockage thermique par chaleur latente (LHTES) sont prometteurs grâce aux matériaux à changement de phase (MCP), capables de stocker/restituer de l'énergie via leur transition solide-liquide. Applicables à la gestion thermique des batteries ou à la récupération de chaleur industrielle, les MCP organiques biosourcés (alcools de sucre, esters) sont attractifs pour les basses/moyennes températures ( 50% of global energy use). Among options, Latent Heat Thermal Energy Storage (LHTES) systems are promising, using Phase Change Materials (PCMs) to store/release thermal energy via solid-liquid transitions. These systems suit applications like battery thermal management, waste heat recovery, and industrial heat recycling. Bio-based organic PCMs (e.g., sugar alcohols, esters) are attractive for low-to-medium temperatures (< °C) due to high latent heat, suitable phase-change ranges, and eco-friendliness. However, their practical use is limited by low thermal conductivity and complex phase-change behavior (e.g., supercooling, polymorphism, mushy zones), which significantly affect thermophysical properties and system performance.

A solution is embedding PCMs in solid porous structures, forming composites that enhance heat transfer, influence natural convection, and promote nucleation. Yet, the physical mechanisms behind phase change in PCM-saturated porous media remain understudied. The impact of porous geometry on melting dynamics, liquid flow, temperature distribution, and solid-liquid interface evolution is hard to quantify experimentally due to limited optical access in opaque systems.

This PhD project aims to experimentally investigate how porous medium geometry and properties affect PCM melting behavior. The work includes two main steps:

- Detailed thermophysical characterization of selected PCMs, focusing on thermal/rheological behavior near phase transition and over repeated cycles. Reliable reference data are crucial, as existing studies are scarce and inconsistent.
- Experimental study of heat transfer and fluid flow during melting in PCM-porous composites under controlled thermal conditions, using Magnetic Resonance Imaging (MRI). This non-invasive technique provides phase identification, local velocity, and temperature mapping in liquid PCMs. Experiments will first use model PCMs (e.g., paraffins) to establish baseline dynamics, then bio-based PCMs with complex behavior.

Expected outcomes include descriptions of liquid flow structures, the role of heat transfer mechanisms, solid-liquid interface evolution, and the influence of porous geometry. The project will advance understanding of phase change, heat transfer, and fluid flow coupling in porous media, contributing to more efficient composite PCMs for LHTES.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Début de la thèse : 01/11/

Funding category

Funding further details

Enseignement supérieur