An overview of the applications of ionic fluids and deep eutectic solvents enhanced by nanoparticles

Ionic liquids and their family known as deep eutectic solvents are non-flammable, nonvolatile, recyclable and environmentally friendly working fluids, making them suitable for use in various thermal systems. By adding nanoparticles to these fluids (through special physical and chemical approaches), one can augment their specifications (especially thermal conductivity). The current review presents, first, some of the latest studies on the thermophysical properties and electrical conductivity of ionanofluids (the mixture of nanoparticles and ionic liquids) and deep eutectic solvents-based nanofluids. Next, their applications in various fields such as solar energy, energy storage systems, and lubricants are reviewed. Finally, the current challenges for the development of these working fluids are listed and some recommendations have been presented for future works.