Heat transfer performance of nano-suspension of Al2O3 in ([C4mim][NT f2]) ionic liquid around a circular cylinder

Abstract

IoNanofluids are a new category of heat transfer fluids synthesized by suspending fine nanoparticles in ionic liquids. These IoNanofluids show superior heat transfer characteristics than conventional nanofluids and are more suitable for medium to high temperature applications. In this study, a numerical analysis of heat transfer performance of nano-suspension of Al2O3 in ([C4mim][NT f2]) ionic fluid around a circular cylinder has been presented. A 2 − D, laminar, steady and forced convective flow around a hot circular cylinder at a constant temperature has been taken into account at 10 ≤ Re ≤ 40 and 0 % ≤ φ ≤ 2.5 %. Governing equations of flow and heat transfer are solved using SIMPLE algorithm based Finite Volume Method (FVM). An unique aspect of this study is the consideration of the influence of temperature on the thermo-physical properties of the IoNanofluids. Heat transfer characteristics are quantified in terms of mean Nusselt numbers and the thermal field around the circular cylinder has been visualized using isotherms. Influence of flow Reynolds number, particle volume fraction and inlet temperature over the local and mean Nusselt numbers has been discussed in detail. Evidently, increase in flow velocity and addition of nanoparticles resulted in heat transfer augmentation. Additionally, heat transfer performance of Al2O3 − ([C4mim][NT f2]) IoNanofluid is compared with the conventional Al2O3 − H2O nanofluid. Comparatively, IoNanofluids outperformed conventional water based nanofluids with 59 % higher heat transfer enhancement ratios. Also, the heat transfer enhancement ratios were noted to be higher at high temperatures. Thus, the new class of cooling liquids (IoNanofluids) are promising working fluids for advanced real time high temperature engineering applications.