Buoyancy Driven Heat Transfer of Nanofluids in a Tilted Enclosure

Abstract

Buoyancy driven heat transfer of water-based nanofluids in a differentially heated, tilted enclosure is investigated in this study. The governing equations (obtained with the Boussinesq approximation) are solved using the polynomial differential quadrature method for an inclination angle ranging from 0 deg to 90 deg, two different ratios of the nanolayer thickness to the original particle radius (0.02 and 0.1), a solid volume fraction ranging from 0% to 20%, and a Rayleigh number varying from 10 4 to 10 6 . Five types of nanoparticles, Cu, Ag, CuO, Al 2 O 3 , and TiO 2 are taken into consideration. The results show that the average heat transfer rate from highest to lowest is for Ag, Cu, CuO, Al 2 O 3 , and TiO 2 . The results also show that for the particle radius generally used in practice (␤ ϭ 0.1 or ␤ ϭ 0.02), the average heat transfer rate increases to 44% for Raϭ 10 4 , to 53% for Raϭ 10 5 , and to 54% for Raϭ 10 6 if the special case of ϭ 90 deg, which also produces the minimum heat transfer rates, is not taken into consideration. As for ϭ 90 deg, the heat transfer enhancement reaches 21% for Raϭ 10 4 , 44% for Raϭ 10 5 , and 138% for Raϭ 10 6 . The average heat transfer rate shows an increasing trend with an increasing inclination angle, and a peak value is detected. Beyond the peak point, the foregoing trend reverses and the average heat transfer rate decreases with a further increase in the inclination angle. Maximum heat transfer takes place at ϭ 45 deg for Raϭ 10 4 and at ϭ 30 deg for Raϭ 10 5 and 10 6 .

Mixed Convection Heat Transfer Enhancement in a Vented Cavity Filled with a Nanofluid

“…It was found that the presence of nanoparticles reduces the strength of flow field, enhances the heat transfer depending on both the strength of convection and the volume fraction of the nanofluid and contributes to stabilize the system. Another study related to natural convection of water-based nanofluids in a differentially heated tilted enclosure was numerically conducted by Kahveci (2010). It was concluded from the results that suspended nanoparticles substantially increase the heat transfer rate and the variation in the average Nusselt number is nearly linear with the solid volume fraction.…”

Three-dimensional natural convection of CNT-water nanofluid confined in an inclined enclosure with Ahmed body

“…The effective density of the nanofluid is assumed to be constant and is given by (Kahveci, 2010) as:…”

Free convection enhancement within a nanofluid’ filled enclosure with square heaters

“…A review of the literature indicates that numerous industrial geometries were investigated [5][6][7][8][9] but almost works were done using rectangular configurations [10][11][12].…”