Amin Shahsavar Goldanloo

The aim of the present study is an investigation of the impact of nanoparticle shape on the hydrothermal characteristics of boehmite alumina nanofluid flowing through a horizontal double-pipe minichannel heat exchanger. Boehmite alumina (γ- AlOOH) nanoparticles of different shapes (i.e. cylindrical, brick, blade, platelet, and spherical) are dispersed in a mixture of water/ethylene glycol as the nanofluid. The effects of the Reynolds number and nanoparticle concentration on the heat transfer rate, overall heat transfer coefficient, effectiveness, pressure drop, pumping power, and performance index are numerically analyzed for different nanoparticle shapes. The results reveal that the nanofluids containing cylindrical and platelet shaped nanoparticles have the highest and lowest thermal conductivity, respectively. Additionally, it is found that the highest and lowest viscosity belong to the nanofluids with platelet shaped and spherical nanoparticles, respectively. Furthermore, it is depicted that, among the considered nanoparticle shapes, platelet shaped demonstrates better heat transfer characteristics, while performance index of the heat exchanger for nanofluid containing spherical nanoparticles is higher. Finally, it is inferred from the obtained results that the increase of Reynolds number and nanoparticle concentration result in a higher heat transfer rate, overall heat transfer coefficient, pressure drop, and pumping power and a lower performance index.