Critical review on local thermal equilibrium and local thermal non-equilibrium approaches for the analysis of forced convective flow through porous media

Scientific community from the field of thermo-fluidics have focused extensive attention towards investigating techniques of enhancing the heat transfer in varied thermal systems. One of the most suitable techniques for augmenting the heat transfer is incorporating porous medium into thermal systems. The transport processes through porous media, which consists of a fluid phase and a solid matrix, can be modelled by either considering both to be in thermal equilibrium or in thermal non-equilibrium. Hence, two different modelling strategies viz. local thermal equilibrium (LTE) model and local thermal non-equilibrium (LTNE) model have been employed by different researchers. In this work, a comprehensive review of the published literatures in respect of the modelling approaches used for determining the implications of embedding porous media in different thermal systems from the perspective of heat transfer and entropy generation has been presented. The effects of various key determinants on the fluid flow, heat transfer characteristics and entropy generation in thermal systems are discussed. This discussion is then followed by a critical assessment of the applicability of LTE and LTNE approaches. At the end, conclusions and recommendations about the less explored systems and the areas that needs further investigations are summarized.