Energy and exergy conditioning of graphene nanoplatelet/water nanofluid circulatory cooled photovoltaic thermal collector

Abstract This test studies were conducted to examine the energy, exergy, and environmental-economic performance improvement of photovoltaic thermal collectors using a graphene nanoplatelet/water nanofluid, which has excellent heat transfer properties, low viscosity increases at low concentrations, nontoxicity, and long-term stability and compatibility. The study aims to contribute to the field by building a brick in the road of linking basic research in nanofluids and photovoltaics. Moreover, although studies of circulatory cooling systems draw on the grid, this research addresses this demand by using renewable energy sources, thereby reducing the grid dependency and increasing energy efficiency. Tests were carried out on photovoltaic thermal collectors (PV/T A and PV/T B ) at concentrations of 0.05 mass% and 0.1 mass% nanofluids, respectively, at a flow rate of 0.4 L min −1 . By circulating nanofluids, PV/T A and PV/T B collectors cooled 9% and 14% under 146 W mean solar power, respectively, while electrical outputs increased 38.31% and 48.74%. PV/T A and PV/T B yielded 37.20 W and 57.91 W of thermal power through removing heat from cells, respectively. The PV-R module, PV/T A and PV/T B had first and second law efficiency values of 7.67%, 35.86%, 50.89%, and 8.24%, 11.9%, 13.6%, respectively. The additional gain from cooling in the form of heat load and increased electricity output of the PV/T A and PV/T B increased the rate of solar energy utilization by 28.5% and 43.5%, respectively. This improvement can be considered as an environmental benefit, considering the equivalent reduction in CO 2 emissions from the grid emission factor of 84.88 kg year −1 for PV/T A and 139.64 kg year −1 for PV/T B .