Investigation of the application of nanotechnology to increase the direct absorption of solar radiation

The purpose of this study is to evaluate the potential of solar nanofluids (liquid with dispersed nanoparticles) for direct absorption of solar radiation and steam production. At present, solar thermal energy systems suffer great losses due to heat transfer processes, therefore, the development of nanotechnology and its achievements such as various nanoparticles, has created high hopes to increase the efficiency of solar collectors through direct absorption of sunlight. In order to make optimal use of solar nanofluid systems, it is necessary to identify and study them. In this research, four different nanofluids have been synthesized, identified and evaluated. Two of them were water-based nanofluids and the other two were thermal oil-based nanofluids. Also, the optical properties of nanofluids were measured at room temperature with a spectrophotometer and compared with the base fluid. The optical properties, in addition to being measured at room temperature, have also been evaluated after heat treatment on nanofluids at high temperatures. This temperature increase is intended to recreate operating conditions for those closer to the actual applications. DLS measurements show a similar hydrodynamic average of 138 nm for the sample containing SDS and 135 nm for the sample containing SDS and PVP.