Abstract

In latent heat storage, certain non-phase change materials (non-PCMs) with high thermal conductivity are incorporated into the phase change materials (PCMs)  with the aim of enhancing the efficiency of heat/cold storage. We term this type of non-PCMs as “enhancer”, which includes materials like graphite and copper foam, usually with a complex skeleton structure. In this talk, we propose a phase field model to describe the solidification and melting phenomena of PCMs with enhancer from a microscopic point of view. Our model is governed by the energy equation coupled with the Allen-Cahn equation. A penalty technique is applied in the Allen-Cahn equation to describe the complex structure of the non-PCMs. We use the concept of thermal resistance to define the boundary condition on the contact interface of two materials to ensure the temperature jump.  Thanks to the hybrid dual formulation, the temperature can be solved as a monolithic function while satisfying the temperature jump on the material interface. In temporal discretization, a numerical scheme is developed to decouple the phase field from the temperature. In the spatial discretization, the hybrid finite element method, the Raviart-Thomas elements are used to solve the temperature and  to satisfy the temperature jump on the interface.   2D and 3D simulations are carried out for both melting and solidification processes of a fossil based organic PCM, RODATHERM60 in the graphite skeleton on different porous structures to validate our model.

Biography

Professor Majdi Azaiez is a full professor at the Polytechnic Institute of Bordeaux and a senior researcher at the Institute of Mechanics and Engineering of Bordeaux, based at the University of Bordeaux, France. Since joining the institute in 2002, he has made significant contributions to the fields of applied mathematics and computational fluid mechanics. 

Professor Azaiez earned his Ph.D. in Applied Mathematics from Orsay Paris XI University in 1990, under the guidance of leading experts in the field. Early in his career, he was a researcher at CRS4 in Italy, collaborating with renowned mathematician Professor Alfio Quarteroni. From 1992 to 2002, he served as an assistant professor at Paul Sabatier University in Toulouse, where he further honed his teaching and research expertise. 

Throughout his career, Professor Azaiez has been invited as a visiting professor at prestigious institutions worldwide, including École Polytechnique Fédérale de Lausanne (EPFL), the University of Seville, Nanyang Technological University (NTU), and Xiamen University, among others. 

His research interests span a broad spectrum of topics, including the development of high-order numerical methods for partial differential equations (PDEs), inverse problems, constrained eigenvalue computations, and advanced techniques in model and data reduction.