Greenʹs functions theory combined with the FVM–BEM method for more accuracy in the storage energy domain

This note presents the study of laminar flow under forced convection in buried co-axial exchanger. No usual boundary condition at the exchanger wall is imposed. The wall temperature as well as the wall heat flux and the Nusselt number will be calculated. A hybrid model consisting of a finite element method at the boundary (BEM) for the heat transfer problem on the boundary and a finite volume method (FVM) to solve the laminar flow inside solves this problem. The development of the BEM method is based on the Greenʹs functions theory (GFT). This conjugate method allows to have fast results and to foresee the thermal behavior of the exchanger. The temperature field, the heat flux density and the Nusselt number are investigated. The results is compared to those obtained using the commercial CFD package Fluent. The results can be used to improve the heat transfer rate of exchangers. In addition, they can be of great interest in industrial processes requiring the estimation of the heating time necessary to obtain steady states in other similar cases.