Jury :

• Marie Duquesne HDR Lecturer at Bordeaux INP-ENSCPB Rapporteure
  Jaona Randrianalisoa HDR Lecturer at ESIReims Rapporteur
  Lingai Luo Director of Research CNRS Nantes President
  Michel Quintard Director of Research CNRS Toulouse Examinateur
  Martin Raynaud Thermal expert at Thales Alenia Space Examinateur
  Philippe Pernod Professor at Centrale Lille/IEMN Co-Director
  Philippe Coquet Professor at the University of Lille/CINTRA Co-Director
  Olivier Bou Matar Professor at Centrale Lille/IEMN Co-Encadrant
  Stefano Giordano Research Fellow at the IEMN Invité
  Jerome Foncin Thermal expert at Thales LAS Invité

Summary:

Phase change materials (P C M) are widely used for thermal management applications because of their high latent heat of fusion. Despite this, P C M's suffer from their low thermal conductivity, which limits the propagation of heat around the source, and without a significant improvement in conductivity, melting only takes place around the heat source, greatly limiting the performance of the device. To counter this, a multitude of thermal reinforcements have been developed and studied in recent years. A review of the literature details the study of these different reinforcements and their performance when combined with P C M in the first chapter of this manuscript. The second chapter presents a new reinforcement based on the use of metal lattices and a model for evaluating its thermal properties. The next chapter studies the use of such a reinforcement for the thermal management of a concrete case, both theoretically and experimentally. Finally, the last chapter presents the use of a new type of reinforcement based on the Cas cadedstorage principle, which consists of locally modifying the proportion of reinforcement in order to optimise heat transfer and heat absorption by the P C M.

Abstract:

Phase Change Material (P C M) have been widely used for thermal energy storage due to their highlatent heat of fusion for thermal management applications. However, P C M suffer from their verylow thermal conductivity which limits heat spreading around the heat source. Without properthermal conductivity enhancement, melting would occur mainly around the heat source and heatwould be conducted too slowly for the device to be efficient. To do so, a variety of fillers have beenendeveloped and extensively studied in the past decades. A thorough literature review of the differ-ent fillers as well as their behavior when combined with P C M is presented in the first part of themanuscript. Then, a new kind of architected filler based on metal lattice structure is presentedalongside with a model allowing to evaluate its performances. The following chapter presents acombined theoretical and experimental study on the implementation of such filler on a relevantuse-case. The final chapter of the thesis displays another kind of fillers based on the cascadedstorage principle which consists in adapting locally the filler's volume ratio to enhance heat con-duction and optimize P C M heat absorption