Experimental analysis of forced convection heat transfer of Hybrid Nanofluids in a vertical annulus with cosine heat flux

Abstract

In this paper, the effect of hybrid Nanofluids on heat transfer of flow around a vertical rod with cosine heat flux is investigated. TiO2 and Al2O3 Nanoparticles are added to deionized water to produce hybrid Nanofluids. Experiments are conducted for both turbulence and laminar flow regimes. The test rig is an annulus in which a pitch-variable helical element applies a cosine heat flux to its inner tube. Results reveal that the increase in concentrations would reduce maximum rod temperature significantly. This is near l20% for 1.5%Al2O3 compared to water. The effect of pressure was also studied. The data obtained at pressures of 1, 2, 5, and 10 bar shows that pressure does not affect heat transfer performance. The thermal enhancement of Nanofluid decreases as the Reynolds number increases.