Viscous dissipative forced convection in thermal non-equilibrium nanofluid-saturated porous media embedded in microchannels

Under local thermal non-equilibrium and isoflux boundary conditions, the two-energy-equation model is employed to investigate the effect of viscous dissipation on the thermal characteristics of nanofluid flow through a porous medium embedded in a microchannel. Analytical closed-form solutions of the two-dimensional temperature distributions are obtained for the models with and without the viscous dissipation terms in the energy equation. The analysis emphasizes on the disparities induced by the viscous dissipation between the two models. The use of porous medium is capable to enhance the thermal performance up to 53%. When the viscous dissipation effect is neglected, the thermal performance of nanofluid is overrated as much as 60%, sufficiently serious to trigger an attention in the performance analysis. The heat transfer coefficient of nanofluid is found to be enhanced in the low-Reynolds-number flow regime but it declines in the high-Reynolds-number flow regime. By reducing the size of nanoparticle, the thermal performance can be enhanced as much as 70%. Furthermore, the thermal performance can be further augmented by increasing the channel aspect ratio as well as by increasing the thermal conductivity of the porous material. This study serves as a useful analytical tool for the design and performance characterization of an integrated system incorporating the use of nanofluid and porous medium into a microchannel.