Experimental investigation of graphene nanoplatelets nanofluid-based volumetric solar collector for domestic hot water systems

Today, with growth of population and increasing dependence of industry and technology on fossil energy, all communities and countries will face the challenge of energy in the future. Among all types of renewable energies, solar energy is a proper alternative to fossil fuels. For it is available in most parts of the world. In this study, the experimental investigation of volumetric solar collector's performance which is applied in domestic hot water has been shown for the first time, by making a laboratory sample of a volumetric collector, using innovative application of graphene nanoplatelets/deionized water with weight fractions of 0.0005, 0.001 and 0.005. The experiments were carried based on EN 12975-2 at different inlet temperatures and three mass flow rate of 0.0075, 0.015 and 0.225 kg/s. The results showed that the collector efficiency increases by the nanofluid weight fraction increase. According to the results, the maximum collector efficiency is obtained at 0.015 kg flow rate for both the base fluid and nanofluids. The zero-loss efficiencies using nanofluids with weight fractions of 0.0005, 0.001 and 0.005 were 83.5%, 89.7% and 93.2%, respectively; whereas the zero-loss efficiency was 70% using the base fluid.