Experimental study of convective heat transfer and pressure loss of SiO<inf>2</inf>/water nanofluids Part 1: Nanofluid characterization - Imposed wall temperature

Abstract

This paper describes an experimental study on the convective heat transfer of SiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> /water nanofluids inside a circular tube with imposed wall temperature. To our knowledge, very few papers have been published with temperature boundary conditions and none in cooling conditions. The experimental apparatus is described which allows us to measure local wall temperatures as well as fluid inlet/outlet temperatures. The flow regimes range from laminar to turbulent. The Reynolds and Nusselt numbers are deduced by using thermal conductivity and viscosity values measured with the same temperature conditions as those in the tests. The shear rate influence is also taken into account in the viscosity determination.The results indicate that the general trend of standard correlations is respected. However, the heat transfer coefficient values are higher than observed with pure water. An explanation is proposed.