Simulation of Heat Transfer of High-Concentration Al2O3/Water NanofluidEffect of Reynolds Number

Nanofluids are suspensions of metal or metal oxide nano particles in base fluids (e.g. water, oil, etc.) The thermal advantage of nanofluids is that they provide higher thermal conductivity over base fluids. The overall effect is better heat transfer in engineering applications. The literature has a considerable number of disagreements with regard to the properties and performance of nanofluids as heat transfer fluids. This paper is part of a series of systematic studies to address this issue. In this paper, simulation of heat transfer of nanofluid made from aluminum oxide Al2O3 suspended in deionized water are presented. The solid particle volume concentration was 1.5%. Key properties of nanofluid were obtained from correlations available in the literature. The nanofluid flowed in a circular pipe having an internal diameter 5.25 cm and a length 16.51 cm. The pipe was subjected to constant heat flux of 74,948 W/m(2). At the inlet, the fluid's temperature was constant at 295 degrees K, and the entrance velocity ranged between 0.029 and 0.038 m/s (uniform profile). All data was in the laminar flow regime. The single-phase model for each nanofluid was utilized. All simulations were conducted utilizing ANSYS Fluent. The mesh-independent results showed that the local surface temperature decreased and local Nusselt number increased with increasing velocity. A similar simulation was run for water under the same conditions. The heat transfer performance of the nanofluid was found to be superior to that of clear water.