Title : Advanced Lattice Boltzmann simulation of melting/solidifying processes of a composite metal foam/paraffin through a rectangular channel
This work performs a numerical investigation of time-dependent forced convection heat transfer in a rectangular openended channel fully filled with a porous structure (metal foam) and saturated with a phase change material (PCM) which is the paraffin. The unsteady two-dimensional governing equations, based on the Darcy- Brinkmann-Forchheimer (DBF) model for the dynamic field and the local thermal non-equilibrium (LTNE) condition for the thermal field at the representative elementary volume (REV) scale in their dimensionless forms, have been simulated using the thermal Single Relaxation Time (T-SRT) Lattice Boltzmann Method (LBM). Three distribution functions are used to handle the fluid, and temperature of both fluid and solid phases. A comparison with previous results in literature is done to valid the in-house code and proves its reliability. Effects of Reynolds number, Eckert number, porosity and pore density on dynamic and thermal fields, entropy generation, bejan number and energy and exergy efficiencies of the system deemed are analyzed. The relevance of these parameters is highlighted and discussed during the charging (melting) and discharging (solidifying) cycles. Based on the results obtained, it can be stated that low porosity values (0.4 and 0.6) promptly speed up these two processes owing to high thermal conductivity of the metal foam and then, enhance energy and exergy efficiencies of the device, whatever Re. Besides, streamlines, isotherms and melt front (phase field) are presented. In addition, it can be concluded that there is a critical Reynolds number (around 400) for which the quantity of the storage energy is optimal and whose quality is large depending on both the porosity and the viscous dissipation effects.