Heat transfer enhancement of nanofluids in a four-blade LPD static mixer

Abstract

The heat transfer performance of nanofluids within a four-bladed LPD static mixer was investigated using a combination of experiments and simulations under constant heat flow boundary conditions with Re ranging from 3519 to 16719. Al2O3-H2O nanofluid with volume fraction φ = 0.3 % was prepared experimentally and the stability of the nanofluid was analyzed by settling observation method and Dynamic light scattering (DLS). Numerical simulations were adopted to analyze the effects of nanoparticle types, volume fractions and types of mixing nanofluids on the heat transfer enhancement inside the four-bladed LPD static mixer. The results show that the maximum error of Nusselt number (Nu) between the predicted values of Mixture model and experimental values was 7.39 %. Because of the combined heat transfer performance coefficient PEC more than 1 with the increasing of Re, the mixers with α = 30° and β = 45° instead of KSM could be recommended when Re > 5279. The PEC of Al2O3-H2O nanofluids gradually increases with the increasing φ. At the same Re and φ, the flied synergy number Fc and PEC of the mixed nanofluids are 1.01–1.47 times and 1.15–3.35 times higher than those of the single nanofluids.