Nanofluids are fluids containing suspended nanoparticles, typically with sizes ranging from 1 to 100 nanometers. These nanoparticles can be made from various materials, such as metals, oxides, or carbon nanotubes. In solar thermal systems, nanofluids are used as heat transfer fluids to improve the efficiency of heat transfer processes.
The commercial implementation of nanofluids for solar thermal applications is still in its early stages. However, several pilot projects and demonstration systems have shown promising results.