Experimental analysis of W/EG based Al2O3-MWCNT non-Newtonian hybrid nanofluid by employing helical tape inserts inside a corrugated tube

Abstract

Experimental analyses have been undertaken on friction factors and convective heat transfer using a helically corrugated tube (HCT) equipped with inserts, under laminar flow conditions. Water-ethylene glycol mixture with Al2O3-MWCNT hybrid nanofluids has been employed. The investigation focused on examining the synergistic effects of hybrid nanofluids, triangularly helical tape (THT) inserts and helical corrugation within the tubes on the friction factor, Nusselt number, and thermal performance factor (TPF). The fluid displayed non-Newtonian behaviour at volume fractions greater than 0.1 %. The study indicated that augmenting the concentration of Al2O3-MWCNT in the hybrid nanofluid and decreasing the helix ratio of the THT inserts led to increased heat transfer rates and TPF. The peak TPF of 2.31 was recorded when using the W/EG based Al2O3-MWCNT hybrid nanofluid with a 1 % volume fraction in an HCT equipped with THT inserts with a helix ratio of 2 at a Reynolds number of 2000. Moreover, Al2O3-MWCNT exhibits an average Nusselt number of 42.5 %, 49.47 %, and 56.2 % higher than the base fluid at φ = 0.1 %, 0.5 %, and 1 %, respectively.