Influence of solid phase thermal conductivity on species separation rate in packed thermogravitational columns: A direct numerical simulation model

In this work, a direct numerical simulation model has been proposed to study the influence of porous matrix thermal properties on the separation rate in a model of packed thermogravitational column saturated by a binary mixture.The coupled flow, heat and mass dimensionless equations and boundary conditions have been derived in pore-scale and then solved over a vertical column containing fluid and solid phases.The results show that the separation rate is changed significantly by the conductivity ratio of the solid/fluid phases. The classical maximum separation at optimal Rayleigh number increases by decreasing the solid thermal conductivity. We obtained that the influence of the solid thermal conductivity for small Rayleigh number is not considerable but for intermediate Rayleigh number the separation rate initially decreases with increasing the thermal conductivity ratio and then reaches an asymptote. As the Rayleigh number increases, convection dominates and the effect of thermal conductivity ratio on separation rate becomes completely inversed.