Experimental study of water-based CuO nanofluid flow in heat pipe solar collector

The main goal of this study is the experimental evaluation of the thermal performance of heat pipe solar collector (HPSC) at different high flow rates of water and CuO–water nanofluid with various volume fractions. In this regard, a test bench of the HPSC was manufactured and tested in the laboratory of Vali-e-Asr University, while the co-precipitation method was used to prepare CuO nanoparticles. The structural and optical properties of the nanostructure were characterized by means of X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and UV–visible analysis. The collector efficiency and pumping power were calculated for nanofluids, and the results were compared with ones of water working fluid; based on the experimental results, copper oxide nanofluid and deionized water at a volume fraction of 0.017 and a flow rate of 14 L min⁻¹ yields the greatest improvement in the efficiency of the solar collector. The results also showed that the efficiency of solar collector increases with the flow rate and the volume fraction of the nanofluid.