An experimental study of forced convection effectiveness of Al_2O_3-water nanofluid flowing in circular tubes

摘要

In the present study, experimental efforts have been performed to explore the forced convection heat transfer using water-based suspension of Al_2O_3 nanoparticles (nanofluid) to replace the pure water as the working fluids in circular tubes. The nanofluid was prepared as a functional forced convection fluid and the thermal properties including the density, thermal conductivity, and dynamic viscosity were investigated experimentally. Besides, forced convection heat transfer in circular tubes was investigated with water-based nanofluid containing various mass fractions of the Al_2O_3 nanoparticles (2,5, and 10 wt%) under the following operating conditions: the volume flow rate Q_f-= 23.6-183.5 cm~3/min (the Reynolds number Re_(f,0) = 188-2095), the heating power applied at the outer wall of the tube q"(0,eff) = 1908-7362 W/m~2, and the inlet fluid temperature T_(in) = 24.5-25.5 °C or 49.5-50.5 °C. Measured data showed that the dispersion of increasing mass fraction of A1_20_3 nanoparticles can effectively improve the thermal conductivity relative to the pure water. Besides, higher average heat transfer effectiveness ξ_(h.btd )and figure of merit FOM are noted for the cases with higher inlet fluid temperature T_(in).