A stable heat transfer oil-based copper nanofluid is prepared via one-step chemical synthesis method,within which a certain proportion of silica nanoparticles is added to prepare Cu-SiO2 composite nanofluid.The variations of transmittance of the prepared nanofluid upon wavelength are tested and compared by using spectrophotometer,and the photothermal shift effect of the nanofluid is investigated through smothering experiment.Results indicate that the transmittance of Cu-SiO2 composite nanofluid with the addition of silica decreases dramatically.The photothermal shift effect of Cu-SiO2 composite nanofluid is enhanced with the increase of the total mass fraction and there exists an optimal mass fraction of 0.6％.It can be heated up to 200℃after 30 min of light exposure,showing a remarkable improvement of heat-collecting performance.The optimal photothermal conversion effect can be obtained for the composite nanofluid under m(Cu)∶m(SiO2)=4∶2.
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