Dependence of photothermal conversion characteristics on different nanoparticle dispersions

The efficiency of nanoparticle-based direct absorption solar collector (DASC) is strongly dependent on the materials, where a systematic study is still lacking. This work conducts an experimental study of the photothermal conversion characteristics of a number of nanoparticle dispersions including Au, Si, Fe₃O₄ , Al₂O₃ and diamond under the same experimental setup. The results show that comparing with the base fluid, the introduction of nanoparticles can increase the photothermal conversion efficiency significantly, and the efficiency increases in the order of Al₂O₃ , diamond, (Fe₃O₄ and Si) and Au. For a given total mass concentration, the Fe₃O₄ -Au hybrid nanofluid is found to possess a higher efficiency than that of pure Au alone. Three possible mechanisms are proposed for the influence of nanoparticle materials, which can qualitatively explain the experimental results.