Stability, Thermophysical, Optical and Photothermal Properties of ZnO Nanofluids with Added Anionic/Cationic Mixed Surfactants

Metal oxide nanofluid is a new type of heat transfer medium with good thermal performance, which can be used to improve the heat collection and photothermal conversion performance of the collector. The development of new nanofluids with excellent stability, thermophysical and photothermal properties is very important for solar thermal utilization. In this paper, the ZnO nanofluids with SDS/CTAB mixed surfactants were prepared by two-step method. Their stability, thermophysical, optical and photothermal properties were studied based on experimental data. Then, the optimum concentration and preparation conditions of the proposed ZnO nanofluids adding SDS/CTAB with good photothermal performance were obtained. The results showed that the ZnO nanofluids with the addition of SDS/CTAB hybrid surfactant has good dispersion stability and its thermal conductivity can reach 0.772 W/(m·K). The transmittance was as low as 19.0.10% and the extinction coefficient was as high as 7.25 cm−1. In addition, the addition of the SDS/CTAB hybrid surfactant caused the ZnO nanofluids to exhibit better photothermal conversion efficiency up to 87%, which was superior to that of the control group with the addition of other surfactants. Therefore, ZnO nanofluids with the addition of SDS/CTAB have great potential as DASC working fluids. Highlights ZnO nanofluids with SDS/CTAB mixed surfactants were prepared. The thermal properties, stability, optical properties and photothermal properties of the prepared ZnO nanofluids were analyzed. The results show that the prepared nanofluids have great potential as the working medium of DASC.