Experimental Study on Laminar Forced Convection of Al2O3/Water and Multiwall Carbon Nanotubes/Water Nanofluid of Varied Particle Concentration with Helical Twisted Tape Inserts in Pipe Flow

Abstract

In this study an experimental investigation has been carried out to analyze the laminar forced convection of Al2O3/water and multiwall carbon nanotubes (MWCNT)/water nanofluids through uniformly heated horizontal circular pipe with helical twisted tape inserts. Tests were conducted for varied range of nanoparticle volume concentration (0.15%, 0.45%, 0.60%, and 1%) and helical tape inserts of twist ratios of 1.5, 2.5, and 3. The heat transfer enhancement and the increase of friction factor of nanofluids with helical inserts are compared with that of pure water results with plain tube without inserts. The Nusselt number is found to increase with the increase in Peclet number and nanofluid concentration. The MWCNT/water nanofluids with helical screw tape inserts exhibits higher thermal performance compared to Al2O3/water nanofluid. The maximum thermal performance factor was found to be 1.79 and 1.99 for Al2O3/water and MWCNT/water nanofluids with helical twisted tape inserts, respectively. The pressure drop for Al2O3nanofluid is found to be higher compared to the MWCNT nanofluid for all the twist ratio of helical screw tape inserts. © 2018 Taylor & Francis Group, LLC.