A review of studies using nanofluids in flat-plate and direct absorption solar collectors

With increasing energy demands worldwide, the consumption of fossil fuels has increased unprecedently which are scarce in nature. This has led to environmental degradation and global warming which is a matter of concern. These factors lead to the rise in renewable energy sector in last decade. Among various renewable energy sources, solar energy is most exclusively used because of its ease of availability and least impact on the environment. Flat plate solar collector is most widely used solar collector but is less efficient (low capability to convert solar energy to thermal energy). The use of nanofluid (fluid obtained by mixing nanoparticle in base fluid) in place of base fluid has improved effect on thermophysical properties such as thermal conductivity. The use of nanofluid on flat plate solar collector (FPSC) & direct absorption solar collector (DASC) can be identified as an effective way to enhance the performance of solar collector. With the advancement in nanotechnology and growing thrust over increasing the performance of solar devices a lot of work has been done in this regard. The purpose of this literature review is to summarize the various research work done on the application of nanofluid in solar thermal devices. This review paper identifies the effect of various parameters and the optimum working condition. This paper also identifies the probable challenges we ought to face while developing thermal collector using nanofluids thus identifying the opportunities for future research.