Mixed convection phenomenon in packed beds: a comprehensive review

This review summarises first the studies that have been performed to date for establishing a suitable model for mixed convection phenomenon in packed beds with working fluids include some simplifying assumptions such as local thermal equilibrium (LTE) condition, neglect of channelling effect, and neglect of thermal dispersion effect. It was found that most of these studies are based on Darcy's model for the flow and on an averaged single equation model (LTE) for the energy equation with using the Boussinesq approximation to represent the variation in fluid density. Theoretical, numerical, or experimental studies, or studies which combine these approaches, are reviewed and for various 2- or 3-dimensional geometries such as horizontal, vertical or inclined parallel plate channels, ducts, cylinders, annuli, etc. In addition, the literature showed that there has been resealable efforts exerted to report works on the non-Darcian mixed convection, in which the effects of boundary, inertia, porosity variation, and inclusion of thermal dispersion under local thermal equilibrium condition (LTE) or under thermal non-equilibrium condition (LTNE).