Thermodynamic properties and evaluation of the lithium nitrate-imidazole IL-water ternary systems as new working fluids for a double-effect AHP cycle

In this work, LiNO3-[EMIM]Cl-H2O and LiNO3-[BMIM]Br-H2O were investigated for a double-effect AHP cycle. The vapor pressure, crystallization temperature, specific heat capacity and specific enthalpy of LiNO3-[EMIM]Cl-H2O were measured systematically and fitted by a least squares method. The vapor pressure of LiNO3-[BMIM]Br-H2O was extended to higher pressures in this study, and other thermodynamic properties were studied in our previous study. The corrosion rates of carbon steel and copper in the two ternary working fluids were measured with a weight loss method at 435.15 K. Based on the measured data, LiNO3-[EMIM]Cl-H2O and LiNO3-[BMIM]Br-H2O were evaluated for the crystallization issue, corrosion issue, as well as the COP in a double-effect AHP cycle for hot water. The COP of the LiNO3-[EMIM]Cl-H2O and LiNO3-[BMIM]Br-H2O system was close to that of the LiNO3H2O and LiBr-H2O system. However, the crystallization temperatures of the new working fluids were at least 20 K lower than that of LiNO3H2O. The corrosiveness of LiNO3-[BMIM]Br-H2O was much less than that of LiBr-H2O and LiNO3-[EMIM]Cl-H2O. The disadvantage whereby LiBr-H2O caused corrosion was relieved by using LiNO3-[BMIM]Br-H2O. LiNO3-[BMIM]Br-H2O can be used as an alternative working fluid in a double-effect AHP cycle and other absorption systems at a high temperature.