Thermophysical properties of [EMIm]Ac and its binary and ternary mixtures with water and graphene nanoplatelets for absorption refrigeration

Abstract

The ionic liquid of 1-Ethyl-3-methylimidazolium acetate ([EMIm]Ac) was investigated as a promising absorbent for absorption refrigeration. Water and graphene nanoplatelets (GNP) were added to the pure [EMIm]Ac ionic liquid to lower its viscosity and improve its thermal conductivity, respectively. The thermophysical properties (density, viscosity, specific heat capacity, thermal conductivity and surface tension) of [EMIm]Ac-water binary and GNP-[EMIm]Ac/water ternary mixtures were investigated. The measured data were fitted with appropriate equations. Comparisons of the thermophysical properties between the ternary/binary mixtures and pure ionic liquid were conducted. Compared to the pure [EMIm]Ac ionic liquid, the viscosity of the GNP-[EMIm]Ac/water ternary system was reduced by up to 94.99% for the 0.05% mass fraction of GNP and a temperature of 282.15 K, and the maximum increment in thermal conductivity was 114.61% for the 1% mass fraction of GNP and a temperature of 353.15 K.