Possible New Heat Transfer Fluid: The IoNanofluid of 1-Ethyl-3-methylimidazolium Dicyanamide + Nano-Titanium Oxide─Studying Its Thermal Conductivity and Viscosity

Abstract

Ionic liquids with the dicyanamide anion, namely, with 1-alkyl-imidazolium cations, have been receiving attention recently due to their potential applications. The utilization of these liquids as heat transfer fluids, specifically in small heat exchangers and microchannels for microprocessor cooling, is presently deemed highly feasible, as it can be both more efficient and environmentally acceptable. The design of a heat transfer equipment that makes use of fluids requires knowledge of their thermophysical properties. In this regard, dispersions of nanoparticles have been extensively studied in recent years to improve thermal conductivity or obtain desirable optical properties. IoNanofluids is what we have taken to name the result of such dispersions in ionic liquids. In this paper, we report measurements of the thermal conductivity and viscosity of the IoNanofluid of 1-ethyl-3-methylimidazolium dicyanamide, [C 2 mim][N(CN) 2 ], with 0.5% mass fraction of TiO 2 nanoparticles (diameter 20 nm) in the temperature range (293 < T/K < 343), at P = 0.1 MPa. Reasonable enhancements were found for thermal conductivity and viscosity, which were temperature-dependent. The IoNanofluid was found to behave as a non-Newtonian fluid in most of the temperature range studied. A discussion about the possible use of this IoNanofluid as a heat transfer fluid shows that it has very promising properties to be used in heat transfer applications.