ABSTRACT
This chapter focuses on the application of the nanofluids in direct absorption solar collectors (DASCs) in which the working fluid is immediately exposed to the incident solar radiation. It investigates the influence of various thermophysical properties and optical properties as well as nanofluid properties on the performance of the low-flux and high-flux DASCs. The chapter discusses challenges and future perspectives of nanofluids. The mass and heat flow of nanofluids are affected by their viscosity. In other words, the pumping power and convective heat transfer have a significant relationship with the nanofluid viscosity. The transmittance of nanofluids, like other optical properties, depends on many elements such as nanoparticles type, base fluid type, path depth, particle size, and concentration. Despite of the growing interest with nanofluids applications in solar collectors, there are some weakness and difficulties that need to be addressed when optimising the application of the nanofluids in the DASCs.
