The enhanced heat transfer of diathermic oil-based alumina-doped zinc oxide nanofluids for domestic solar heating systems

Abstract

Doped material-based nanofluids, as an extension of single-phase nanofluids, expand the performance of heat transfer fluids. In this study, a new type of diathermic oil (DO)-based alumina-doped zinc oxide (AZO) nanofluids was prepared, and the thermophysical characteristics of nanofluids were analyzed. It could be found that the addition of new doped nanoparticles made up for the deficiency in the performance of DO as heat transfer fluid (HTF). Compared with the pure DO, the thermal conductivity of the AZO nanofluids (0.08 mass%) was increased by 8.125%. And the viscosity of nanofluids was decreased by 70% as the temperature increased. So as to further determine the application of nanofluids in the domestic heating system, the parameters of forced convection heat transfer in the tube were analyzed in this article. The convective heat transfer coefficient of AZO nanofluids increased with the increase in temperature. At 50 ℃, the convective heat transfer coefficient of 0.08 mass% AZO nanofluid reached the maximum of 5.49% compared with pure DO. More importantly, this research investigated the heat transfer benefits of using nanofluids in domestic solar heating systems. These promising results indicated that AZO nanofluids showed excellent properties at higher temperatures. It shows DO-based AZO nanofluids application potential in domestic solar heating systems.