Effect of temperature on the hysteresis phenomenon and dispersion regimes for alumina/water based nanofluids

Abstract

The present paper deals with a comprehensive experimental study of the hysteresis phenomenon of alumina-water based nanofluids taking place during heating-cooling cycles. The emphasis was particularly put on the relationship between this phenomenon and the dispersion state of alumina nanoparticles. Thus, by carrying out simultaneous thermal conductivity and dynamic viscosity measurements, five dispersion regimes were highlighted. The influence of the temperature on these two properties as well as the pH of the solution was then investigated for six characteristic conditions in the well-dispersed and chain-like agglomerated regimes and for temperatures between 20 and 80 °C. The results evidenced that as long as the temperature, and as a consequence the pH, does not exceed a critical value, no hysteresis phenomenon occurs during the heating and cooling processes. Eventually, it was found out that this critical temperature is strongly dependent on the dispersion regime and the initial pH of the nanofluid.

Keywords

• Nanofluid
• Hysteresis
• Thermal conductivity
• Dynamic viscosity
• Alumina nanoparticles