SDS SURFACTANT EFFECTS ON STABILITY AND THERMOPHYSICAL PROPERTIES OF Al2O3- WATER BASED NANOFLUIDS

Nanofluids have been considered as new potential heat transfer fluids, but there are controversial results about the stability and thermophysical properties of nanofluids in literature. In this experimental study, nanofluids at different aluminium oxide (Al2O3) volume fractions (0.3-1.1%) and sodium dodecyl sulfate (SDS) surfactant weight fractions (0.2-0.8%) were prepared by utilizing the twostep method. Stability of the obtained nanofluids was determined according to the sedimentation method, zeta potential and average particle size analysis. Density, viscosity and thermal conductivity of the nanofluids were measured experimentally from 298 K to 338 K. According to the results, the nanofluids prepared with 0.2% SDS began to collapse within a few minutes. However, it was observed that the stability of nanofluids prepared with 0.4% SDS, 0.6% SDS, and 0.8% SDS changed with the particle concentration. Besides, relative density values of nanofluids were found to be independent of temperature for each particle concentration. While relative viscosity of nanofluids increased with temperature, the highest relative thermal conductivity values of nanofluids with different weights of SDS were achieved at different temperatures. In general, relative thermal properties tend to increase with an increase in particle concentration. It has been observed that the stability and dispersion of nanofluids have a high effect on thermophysical properties.