An improved lattice Boltzmann method for solid-liquid phase change in porous media under local thermal non-equilibrium conditions

This paper presents an improved lattice Boltzmann (LB) method to simulate solid-liquid phase change with natural convection in porous media under local thermal non-equilibrium (LTNE) conditions. In this method, three distribution functions are respectively adopted for flow field, and temperature field of the PCM and solid matrix. Different from previous models, the present model for temperature field incorporates the total enthalpy and a free parameter in the equilibrium distribution function, and thus could have high computational efficiency by avoiding iteration procedure to deal with phase change. The present model is validated by the melting with natural convection in a square cavity filled with a metal foam. It is found that the numerical results are in good agreement with other numerical results, and the present method could preserve higher accuracy due to numerical diffusion reduction through keeping the relaxation time at around unity as well as tuning the free parameters properly.