Investigation of the combination of TiO₂ nanoparticles and drag reducer polymer effects on the heat transfer and drag characteristics of nanofluids

Abstract

To compensate for drag increment due to the addition of nanoparticles to heat‐transfer fluids, it seems that one could add drag reducer polymeric agents to these fluids. So, in this work, experiments were carried out for solutions of two types of polyacrylamide (FLOPAAM 3330S and FLOPAAM 3630S) at three distinct concentrations (25, 40, and 55 ppm), and TiO2‐water nanofluid at concentrations of 0.015, 0.02, 0.025, and 0.03 L/L. The steady state turbulent convective heat transfer and the friction factor of the suspension of TiO2 in a dilute solution of very high molecular weight, polyacrylamide (hybrid fluid), in a coiled tube were analyzed. Experimental measurements were carried out from a Reynolds number of 11 000 to 21 000 and a constant temperature (24 °C) of the cool bath. The obtained results have shown that for the suspension of nanoparticles, the Nusselt number and drag coefficient increase, whereas for dilute solutions containing only the drag reducer agent, both the Nusselt number and the drag coefficient decrease. However, the combination of the nanoparticle and polymeric drag reducer agent increased the heat transfer coefficient, but decreased the drag coefficient, especially at the highest measured Reynolds number (Re = 21 000).