The synthesis and spectral characterization of copper sulfide nanofluid in a spectral splitting PV/T system

Abstract

The medium utilized in spectral splitting photovoltaic/thermal (PV/T) systems holds immense significance. Previously employed nanofluids, such as polypyrrole, Ag, ZnO, and MgO, exhibited insufficient absorption in the infrared range, hindering the photothermal units from achieving higher temperatures. Copper sulfide (CuS) emerges as a promising alternative nanofluid in PV/T systems due to its superior thermal conductivity and adjustable spectral radiation properties. To assess its suitability, four samples of CuS nanofluid are synthesized under four different oil bathing temperatures, which are 25 ℃, 40 ℃, 60 ℃, and 80 ℃, respectively. What is more, an in-depth examination of CuS nanofluid's optical characteristics and performance is conducted. The U-4100 Spectrophotometer was employed to measure its transmittance, while the Nicolet iS50 was employed to measure its reflectivity. The findings revealed that a 10 mm layer of CuS nanofluid synthesized under 80 ℃ oil bathing temperature possesses distinct selective absorption properties compared to the other three samples of CuS nanofluids. For this CuS nanofluid with the concentration of 100 ug/ml, the transmittance at the wavelength of 600 nm can hit 65 %, while the transmittance in the near-infrared wavelength band is lower than 16 %. These unique optical attributes underscore the potential for CuS nanofluid to be widely adopted in spectral splitting PV/T systems.