Experimental study of steady state laminar forced heat transfer of horizontal annulus tube with non-Newtonian nanofluid

The forced convection steady heat transfer under laminar flow regime in a horizontal annular tube was experimentally investigated in this paper using a non-newtonian, pseudo-plastic nanofluid with an aqueous carboxymethyl cellulose (CMC-0.2 % wt) as the base fluid, and copper oxide (CuO) nanoparticles in 0.5 % wt, 1.0 % wt and 1.5 % volume fractions and Reynolds number from 460 to 1280 and different range of heat flux. The mean and local heat transfer coefficients of the nanofluid were recorded higher than the base fluid at all the applied Reynolds numbers. For instance, at Re = 460, for the nanofluid of 0.5 % vol. concentration, heat transfer coefficient was improved by 14.7 % compared to the base fluid, and by increasing nanofluid concentration to two/three times, heat transfer was improved by 4.4 % and 5.2 %, respectively. The maximum mean heat transfer coefficient was observed for the 1.5 % nanofluid at Re = 1280.