NUMERICAL INVESTIGATION ON LAMINAR FORCED CONVECTION IN TRIANGULAR CROSS SECTION MINI DUCTS WITH NANOFLUIDS AND METAL FOAM

In this study a numerical investigation on laminar forced convection flow of a nanofluid, water–alumina (Al2O3) nanoparticles, in a mini duct with triangular cross section, filled with aluminum foam, is accomplished with the lower heated surface. The duct is related to a heat sink with parallel ducts with triangular cross section and a length of 100 mm. The hydraulic diameter of the single triangular duct is equal to 2.0 mm. A constant and uniform heat flux on the bottom surface of the heat sink is applied and a mixture model approach is employed to simulate the nanofluid flow. The analysis is performed for a three-dimensional combined conductive-convective heat transfer in a square section with triangular duct, at steady state regime. The CFD commercial code Fluent is employed to solve the three-dimensional numerical model by means of a finite volume technique. The investigation covers Reynolds numbers ranging from 200 to 2000 and volumetric concentrations of nanoparticles from 0% to 6%. Results are presented in terms of temperature, average Nusselt number, and required pumping power profiles for various nanoparticle volume fractions. A maximum increase in the average Nusselt number of approximately 35% is observed for a volumetric concentration of 6%. However, a trade-off is evident, as it is associated with an increase in pressure drop.