Research On Ternary Systems Containing1-ethyl-3-methylimidazolium Dimethylphosphate As New Working Fluids

The technology of absorption refrigeration by employing solar energy and industrial waste heat is developing rapidly in today’s society, which is confronted with great energy strain. However, the development of technology of absorption refrigeration is held back due to the inherent weaknesses of widely used working pairs, LiBr-H2O and NH3-H2O for absorption refrigeration at present, with the features of strong corrosion to equipment, easy crystallization, toxicity etc, to name just a few. Therefore, it leads the direction of development to seek new working pairs with wider application and higher efficiency. Many unique properties of Ionic Liquid (IL), such as a nearly zero vapor pressure, ability to be designed (by changing the anion or cation), lower corrosion, strong solubility, thermal stability, consistency in existence under200℃, make it probable to be used as working pairs for absorption refrigeration. The author of this paper put forward ternary systems, with ionic liquid1-ethyl-3-methylimidazolium dimethylphosphate ([EMIM][DMP]), methanol/ethanol and water in it, as the new working pairs for absorption refrigeration, and conducted the experimental study on its thermodynamic properties.The ebulliometer was used to measure the experimental data of gas-liquid equilibrium of the two ternary systems, which contain [EMIM][DMP] and methanol/ethanol and water with different concentrations and under different temperatures. The results reveal that the two systems show negative deviation in terms of Raoult’s law. NRTL model was used to predict the data of the gas-liquid equilibrium of these two ternary systems. The average relative errors of the experimental and predicted values are3.09%and3.89%, respectively,the excess molar enthalpies (HE) of three ternary mixtures for [EMIM][DMP]+methanol/ethanol/water were measured with an isothermal calorimeter made by the author at298.15K and under the normal atmospheric pressure, which show that all the three mixed processes are exothermic. The experimental results have been correlated with the polynomial proposed by Nagata and Tamura (NT) and Cibulka. Meanwhile, NRTL and UNIQUAC equations were employed to predict the ternary systems, and found the relation between HE and the components.The specific heat capacity of ternary mixtures for [EMIM][DMP]+methanol/ethanol+water were measured by the isothermal calorimeter at the temperature ranging from298.15K to323.15K, under the constant atmospheric pressure, and with different concentrations. The data were correlated to find that the relationship between the heat capacity and the temperature.