Experimental investigation on low concentration nanofluids with Fresnel lens and evacuated tubes for solar applications

Abstract

Optical and thermo‐physical properties of the nanofluids play a major role in the absorption of solar energy. In the present study, photo‐thermal energy conversion of low concentration Al2O3/Deionised water (DI) water and CuO/DI water nanofluids in solar thermal collector is experimentally investigated. Properties of 50,100,150, and 200 ppm concentrations of nanofluids are reported. The absorbance results in the visible range indicate that CuO nanofluid of 200 ppm concentration is nearly three times higher compared to Al2O3 nanofluid. The extinction coefficient, optical energy band gap, and photoluminescence obtained from the absorbance data are also reported. Surfactant free nanofluids are used, and the thermal conductivity measurements show a negligible enhancement for both the nanofluids. Maximum receiver temperatures of 89 and 72°C are found with CuO and Al2O3 nanofluids, respectively, for the maximum concentration. A maximum receiver efficiency of 34.89% is obtained for CuO nanofluids.

Investigation of granular natural stone materials as photothermal absorbers for sustainable and environmentally friendly energy harvesting

“…Previous studies have succeeded in creating Fresnel focal point innovations to boost the concentration of light. Pandi et al [16] combined an evacuated tube receiver with a Fresnel lens and 𝐶𝐶𝐶𝐶𝐶𝐶 nanoparticle fluid for a photothermal absorber, achieving a maximum temperature of 89 °C. According to the temperature classification established by Bie et al [1], Fresnel lens collectors can be used for medium temperature applications.…”