Applications of hybrid nanofluids in solar energy, practical limitations and challenges: A critical review

Solar energy is the ultimate perceived solution of incessantly proliferating energy crisis. Diverse range of solar energy conversion systems has been employed to convert solar energy into desired useful form. Performance of solar energy systems is subject to the type of the working fluid that they use for solar energy conversion and transportation. Application of hybrid nanofluids in solar energy systems as working fluid has turned out to be very gainful in terms of performance, owing to distinct thermal transportation characteristics of hybrid nanofluids. Current article has briefly reviewed the studies discoursing the performance of hybrid nanofluid based solar energy systems. Moreover, the performance of solar energy systems based on mono nanofluids has also been overviewed. Considering the importance, fabrication methods and characteristics of hybrid nanofluids as well as their implications on performance parameters of solar systems have been discussed. Reviewed studies have reported remarkable enhancement in power output and efficiency of these systems. However, there are several issues associated with hybrid nanofluids that have abstained the commercialization of binary nanofluid based systems. These issues include instability, increased friction factor, rheological issues, and increased pumping power. Subsequently, economic and ecologic gains of using binary nanofluids in solar energy systems are presented.