aluminum oxide nanofluid energy transfer

nanofluid is a new class of heat transfer fluids engineered by dispersing metallic or non-metallic nanoparticles with a typical size of less than 100 nm in the conventional heat transfer fluids.this article aims to investigate the overall and convection heat transfer coefficient and nusselt number of al2o3-water nanofluid flowing in a horizontal double pipe heat exchanger under turbulent flow () conditions. al2o3 nanoparticles with diameter of 20 nm dispersed in deionized water with volume concentrations of  vol. are used as the test fluid. the results show that the overall and convection heat transfer coefficient and nusselt number of nanofluid were approximately 15% -21% greater than that of pure fluid. additionally, the heat transfer coefficient and nusselt number increase with an increase in flow rate,reynolds number, nanoparticle concentration and nanofluid temperature. finally, the new correlations were proposed for predicting the nusselt number of the nanofluids, especially. employing particles of nanometer dimension suspended in solution as nanofluid shows considerable increase in the nanofluid thermal conductivity and heat transfer coefficient which result in increasing heat transfer and decreasing operational cost.