Experimental investigation into the convective heat transfer and system-level effects of Al2O3-propanol nanofluid

It has been speculated that the application of nanofluids in real systems could lead to smaller, more compact heat exchangers and reductions in material cost. However, few studies have been conducted which have carefully measured the thermo-physical properties and thermal performance of these fluids as well as examine the system-level effects of using these fluids in traditional cooling systems. In this study, dilute suspensions of 10 nm aluminum oxide nanoparticles in propanol (0.5, 1, and 3 wt%) were investigated. Changes in density, specific heat, and thermal conductivity with particle concentration were measured and found to be linear, whereas changes in viscosity were nonlinear and increased sharply with particle loading. Nanofluid heat transfer performance data were generally commensurate with that measured for the baseline. For the 1 wt% concentration, a small but significant enhancement in the heat transfer coefficient was recorded for 1800 < Re < 2800, which is attributed to an earlier transition to turbulent flow. In the case of high particle loading (i.e. 3 wt%), the thermal performance was observed to deteriorate with respect to the baseline case. Discoloration of the fluid was also observed after being cycled at high flow rates and increased temperature.