The heat transfer performances and entropy generation analysis of hybrid nanofluids in a flattened tube

摘要

Highlights•The simulations were performed in laminar flow using hybrid nanofluids.•Nusselt number correlations used in flat tube geometry were discussed.•Thermal conductivity and viscosity correlations of hybrid nanofluids were presented.•Convective heat transfer performances of two hybrid nanofluids were studied.•Entropy generation analysis was performed.AbstractThis article aims to study the heat transfer performances and the degree of thermodynamic irreversibility of two types of hybrid nanofluids, namely MWCNT + Fe3O4/water and ND + Fe3O4/water used in a flattened tube. The three-dimensional numerical analysis was performed for different working conditions as: Reynolds number (within the range 250–2000), volume concentration of hybrid nanoparticles (0–0.3%) and inlet temperatures (from 313 K to 333 K). The numerical results show that the use of hybrid nanofluids in flattened tubes enhances the heat transfer at all studied Reynolds numbers. The MWCNT + Fe3O4/water hybrid nanofluids exhibited higher enhancement in heat transfer compared to ND + Fe3O4/water hybrid nanofluids. In additions, the results indicate that the increase in volume concentration of hybrid nanoparticles leads to the decrease of the total entropy generation of MWCNT + Fe3O4/water and ND + Fe3O4/water hybrid nanofluids compared to base fluid. A reduction of entropy generation of 26.483% compared to the base fluid was obtained for 0.3 vol% MWCNT + Fe3O4hybrid nanoparticles.