Numerical investigation of cooling performance with the use of Al2O3/water nanofluids in a radial flow system

Simulation is conducted to investigate the forced convection flow of Al2O3/water nanofluid in a radial flow cooling system using a single phase approach. Computations are validated with experimental data available in the literature. Results show the same trend as revealed in some of the published works that the Nusselt number increases with the increase of Reynolds number and nanoparticle volume fraction, though the increase in pressure drop is more significant with the increase of particle concentration. Temperature-dependent thermophysical properties of nanofluids are found to have a marked bearing on the simulation. Under a fixed pumping power the nanofluid shows no higher heat transfer rate than water at heat flux q″≤3900q″≤3900 W/m2, while as the heat flux increases the enhancement using a nanofluid becomes more remarkable. Considerable improvements in the average Nusselt number and significant reductions in the thermal resistance under a given pumping power are revealed compared to that of pure water at some supplied heat fluxes. For 4% Al2O3/water mixture at PPrel=0.5PPrel=0.5, the average Nusselt number increases by about 4% and 10% respectively as the heat flux q″=16,000q″=16,000 W/m2 and q″=34,000q″=34,000 W/m2 is applied, while the thermal resistance can be reduced by 2.3% and 7%.