An experimental investigation of thermo-physical properties and heat transfer performance of Al2O3-Aviation Turbine Fuel nanofluids

Aviation Turbine Fuel (ATF)-Al2O3 nanofluids are investigated for better heat transfer performance in a potential application of regeneratively cooled semi-cryogenic rocket engine thrust chambers. The volume concentration of Al2O3 nanoparticles is varied between 0 and 1%. To ensure a realistic evaluation, all properties of the nanofluids are experimentally measured rather than resorting to available formulae or empirical correlations. Among the thermo-physical properties, thermal conductivity and specific heat are measured separately using experimental set-ups fabricated in-house whereas the viscosity is determined using a commercial viscometer. The heat transfer coefficient is determined using a horizontal double tube counter-flow heat exchanger under turbulent flow conditions. At 1% particle volume concentration, the enhancement in the thermal conductivity is 40%, whereas the viscosity increases by 38%. The measured specific heats of the nanofluids do not exhibit appreciable difference within the range of the particle volume concentrations investigated. The heat transfer coefficient increases by 30% at 1% particle volume concentration and correspondingly leads to an enhancement of 10% in the Nusselt number. For the same value of pressure drop, the heat transfer performances of nanofluids are compared with those of ATF. The experimental results show that the maximum enhancement in the heat transfer coefficient observed for the same pressure drop is 28% and even the least enhancement obtained is 2%. (C) 2011 Elsevier Ltd. All rights reserved.