(357d) Thermal Conductivity of Imidazolium Ionic Liquids Saturated with Compressed Gases

The low volatility of ionic liquids (ILs) allows for their potential usage in many engineering applications. Such applications often include systems of gases compressed in ionic liquids. To properly design and characterize such systems, transport property data is needed. Here, the thermal conductivity of several imidazolium based ionic liquids saturated with various compressed gases is measured. Systems reported and analyzed in this study include imidazolium ionic liquids saturated with several hydrofluorocarbon (HFC) gases as well as carbon dioxide at temperatures ranging up to 125 ⁰C and pressures ranging up to 200 bar. For the various IL/HFC systems investigated herein, a slight decrease in thermal conductivity is observed with increasing gas composition. For CO₂/IL systems, a slight decrease in thermal conductivity is observed with increasing gas compositions followed by a gradual increase at higher compositions. The increase in thermal conductivity is attributed to hydrostatic effects as the CO₂ is soluble in the ILs over a broad pressure range. Nevertheless, in all systems investigated here, the thermal conductivity of the mixture remains dominated by that of the pure IL even at large compositions of dissolved gas. This implies that simple composition-based mixing rules for mixture properties based upon pure component properties would not be appropriate.