Application of nanofluid in solar energy harvesting devices: A comprehensive review

The increase in energy demand due to population explosion and the recent global pandemic stressed the need to maximize solar energy harvesting. Nanofluids are used to enhance the performance of solar collectors due to the desirable inherent thermal properties of the fluid. One of the major research trends in solar energy utilization is improving the efficiency of the harvesting devices. Hence, investigating the performance of nanofluid-based solar energy harvesting devices is of great importance. The review presents an overview of the recent advancement in nanofluid-based solar energy harvesting devices and how various parameters such as nanoparticle size, concentration, shapes, and nanofluid flow rates can be manipulated to efficiently harness solar energy from the sun. The type of working fluid used in the collectors significantly influences its performance, and nanofluid performed excellently compared to the conventional fluid. This study investigates the role of nanofluids in various solarpowered desalination systems, parabolic trough solar collectors, flat plate solar collectors, solar dishes, direct absorption solar collectors, evacuated tube solar collectors, solar cookers, and the photovoltaic thermal system. The collector performance was compared for the system with nanofluid and convectional fluid as working fluid based on the heat transfer performance, exergy and energy efficiency improvement, and thermal efficiency enhancement. It is found that maximum collector performance enhancement is obtained using nanofluid. More freshwater was produced with low energy input into a nanofluid-based solar-powered desalination system. The review will update readers on the recent progress made in the field, identify the current challenges and proffer suggestions on how the practical problems can be solved. It is hoped that the review will help young researchers, funding agencies, investors, government, and journal outlets understand the recent advances in this area and what needs to be done for the commercialization of nanofluid as a working fluid in solar collectors.