Effects of pH and Surfactant on the Forced Convection of Al2O3/Water and TiO2/Water Nanofluids

Abstract

The present paper deals with the forced convection of Al2O3/water and TiO2/water nanofluids with the variation of pH and addition of surfactant in nanofluids. The aim of this study is to investigate the effect of suspension stability on the heat transfer and pressure drop characteristics of nanofluids. The present experimental setup is same as used by our earlier paper (Khurana, D., and Subudhi, S., 2019, “Forced Convection of Al2O3/Water Nanofluids With Simple and Modified Spiral Tape Inserts,” Heat Mass Transfer, 55(6), pp. 1–13). The suspension stability of nanofluids is improved by varying pH of nanofluids. The pH in this study is varied from 3.5 ± 0.2 to 12.5 ± 0.2. Addition of surfactants is employed to improve the suspension stability of nanofluids. The sodium dodecyl sulfate (SDS) surfactant of 0.05 wt% is used to increase the stability of nanofluids in the present study. It is observed that by increasing the suspension stability with the variation of pH and addition of surfactant, the heat transfer characteristics have improved appreciably. The maximum enhancement in heat transfer is obtained with TiO2/water nanofluids at a particle concentration of 0.1 vol% and a pH of 3.5 ± 0.2.