Progress, challenges and future prospects of plasmonic nanofluid based direct absorption solar collectors-A state-of-the-art review

The use of nanofluids improves the overall performance of solar thermal collectors and has been studied explicitly in the last decade. More recently, to overcome the limitations of surface based solar collectors, novel nanofluid seeded direct absorption solar collectors (DASCs) have been proposed for effective solar energy conversion. Plasmonic nanofluids, the colloids of plasmonic nanoparticles such as Au, Ag, Cu, Al etc. in base fluids, have emerged as promising thermal media for novel DASCs. Due to the inherent localized surface plasmon resonance effect (LSPR), these novel media show high thermal gain and photo thermal conversion potentials compared to other types of nanofluids. Therefore, this review focuses on recent progress and challenges in the use of plasmonic nanofluids in DASC-based solar thermal applications. The state-of-the-art includes reporting the recent experimental and numerical results in low, medium and high-temperature DASCs as well as hybrid photovoltaic/thermal (PV/T) technology, which utilises nanofluids as beam splitter. We have also tried to provide a review of optical characteristics of plasmonic nanoparticles along with the latest developments in the synthesis of complex nanoparticle morphologies and blends for broadband absorption of solar spectrum. Finally, authors have tried to highlight the challenges, grey areas and possible future research directions for the potential applications of plasmonic nanoparticles in futuristic solar harvesting applications.