Optimization of natural convection heat transfer of Newtonian nanofluids in a cylindrical enclosure

doi:10.1016/j.cjche.2015.04.002

Abstract

Abstract: This study characterizes and optimizes natural convection heat transfer of two Newtonian Al₂O₃ and TiO₂/water nanofluids in a cylindrical enclosure. Nusselt number (Nu) of nanofluids in relation to Rayleigh number (Ra) for different concentrations of nanofluids is investigated at different configurations and orientations of the enclosure. Results show that adding nanoparticles towater has a negligible or even adverse influence upon natural convection heat transfer of water: only a slight increase in natural convection heat transfer of Al₂O₃/water is observed, while natural convection heat transfer for TiO₂/water nanofluid is inferior to that for the base fluid. Results also reveal that at low Ra, the likelihood of enhancement in natural convection heat transfer ismore than at high Ra: at low Ra, inclination angle, aspect ratio of the enclosure and nanoparticle concentration influence natural convection heat transfer more pronouncedly than that in high Ra.

Key words: Natural convection heat transfer, Nanofluid, Optimization, Cylinder orientation

摘要： This study characterizes and optimizes natural convection heat transfer of two Newtonian Al₂O₃ and TiO₂/water nanofluids in a cylindrical enclosure. Nusselt number (Nu) of nanofluids in relation to Rayleigh number (Ra) for different concentrations of nanofluids is investigated at different configurations and orientations of the enclosure. Results show that adding nanoparticles towater has a negligible or even adverse influence upon natural convection heat transfer of water: only a slight increase in natural convection heat transfer of Al₂O₃/water is observed, while natural convection heat transfer for TiO₂/water nanofluid is inferior to that for the base fluid. Results also reveal that at low Ra, the likelihood of enhancement in natural convection heat transfer ismore than at high Ra: at low Ra, inclination angle, aspect ratio of the enclosure and nanoparticle concentration influence natural convection heat transfer more pronouncedly than that in high Ra.

关键词: Natural convection heat transfer, Nanofluid, Optimization, Cylinder orientation

Hamid Moradi, Bahamin Bazooyar, Ahmad Moheb, Seyed Gholamreza Etemad. Optimization of natural convection heat transfer of Newtonian nanofluids in a cylindrical enclosure[J]. Chin.J.Chem.Eng., 2015, 23(8): 1266-1274.

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