Thermal and hydraulic characteristics of turbulent nanofluids flow in a rib-groove channel

Thermal and hydraulic characteristics of turbulent nanofluids flow in a rib-groove channel are numerically investigated. The continuity, momentum and energy equations were solved by means of a finite volume method (FVM). The top and bottom walls of the channel are heated at a constant temperature. Nine different rib-groove shapes are considered in this study, which are three different rib shapes with three different groove shapes including rectangular, triangular and trapezoidal and they are interchanged with each other. Four different types of nanoparticles Al2O3, CuO, SiO2, and ZnO with different volume fractions in the range of 1% to 4% and different nanoparticle diameters in the range of 25 nm to 80 nm, are dispersed in different base fluids (water, glycerin, engine oil) are used. In this study, several parameters such as different Reynolds numbers in the range of 5000<20000, and different rib-groove aspect ratios in the range of 0.5 <= AR <= 4 are also examined to identify their effeets on the heat transfer and fluid flow characteristics. The results indicate that the rectangular rib-triangular groove has the highest Nusselt number among other rib-groove shapes. The SiO2 nanofluid has the highest Nusselt number compared with other nanofluid types. The Nusselt number increased as the nanoparticle volume fraction, Reynolds number and aspect ratio increased; however, it decreased as the nanoparticle diameter increased. It is found that the glycerin-SiO2 shows the best heat transfer enhancement compared with other tested base fluids. (C) 2012 Elsevier Ltd. All rights reserved.