Comparison of thermal performance between a surface and a volumetric absorption solar collector using water and Fe3O4 nanofluid

In this study, the thermal performance of a surface absorption solar collector (SASC) and a volumetric absorption solar collector (VASC) using water and Fe3O4 nanofluid was experimentally investigated. As a result, the heat removal factor (FR) and overall heat loss coefficient (UL) of the SASC were increased with the concentration and mass flow rate of the Fe3O4 nanofluid. The limit-normalized temperature difference (LNTD) of the SASC was reduced compared with that of water because of increased heat loss due to the improved heat transfer performance of the Fe3O4 nanofluid. In addition, the thermal and exergy efficiencies of the SASC using the Fe3O4 nanofluid were lower than those using water. However, in the case of the VASC, FR increased while UL decreased with the increasing mass flow rate of the Fe3O4 nanofluid. When the mass flow rate and concentration of the Fe3O4 nanofluid increase, its LNTD increased beyond water. The thermal and exergy efficiencies of the VASC using the Fe3O4 nanofluid were higher than those using water. Moreover, the maximum thermal and exergy efficiencies was the maximum when the 0.05 wt% Fe3O4 nanofluid was used in the VASC. (C) 2021 Elsevier Ltd. All rights reserved.