Research On Basic Physical Properties Of Ionic Liquid Absorption Refrigerants

Ionic liquids have good physical and chemical properties,non-corrosive,non-volatile,and miscible with refrigerants.They can overcome the shortcomings of traditional absorption systems such as crystallization,corrosion,and distillation efficiency reduction,and have great application research value.In this paper,the basic physical properties and cycle characteristics of ionic liquid refrigerant working pairs are studied through experimental measurements and numerical simulations.The laser diffusion method was used to measure the diffusion coefficients of[mmim]DMP/H₂O and[mmim]DMP/CH₃OH binary solutions under different magnetic field intensities.The correlation and error analysis of experimental data were carried out,and the effects of magnetic field strength and refrigerant mass fraction on the diffusion coefficient were discussed.The experimental results show that the diffusion rate of the[mmim]DMP/H₂O and[mmim]DMP/CH₃OH solution accelerates significantly in a magnetic field environment.As the mass fraction increases,it decreases.A vapor-liquid equilibrium experiment platform for[Na?TX-7?]SCN/NH₃ binary solution was set up.The saturated vapor pressure of the solution in the temperature range of 293.15 K-373.15 K was measured by the static method.The pressure temperature mole fraction?P-T-x?diagram was drawn.The experimental data were correlated using the NRTL model and compared with the saturated vapor pressures of other ionic liquid working medium pairs.The comparison shows that although the solubility of NH₃ in[Na?TX-7?]SCN is lower than that in NaSCN,it is much higher than that in other conventional ionic liquids.A differential scanning calorimeter?DSC?was used to measure the specific heat capacity of the ionic liquid[Na?TX-7?]SCN in the 293.15 K-473.15 K temperature range,and a linear empirical correlation was established.Wilson model was used to predict the excess enthalpy of[Na?TX-7?]SCN/NH₃solution and calculate the specific enthalpy of the solution.Based on the basic physical properties of the ionic liquid[Na?TX-7?]SCN and[Na?TX-7?]SCN/NH₃ binary solution,and the relationship between mass and energy conservation of each component of the system,the steady-state mathematical model of single effect absorption refrigeration?heat pump?system is established and simulated.The simulation results are compared with the literature data.The results show that the performance of the[Na?TX-7?]SCN/NH₃ absorption refrigeration system is better than that of the H₂O/NH₃ system,and it is particularly suitable for operation at higher generation and evaporation temperatures.The performance of[Na?TX-7?]SCN/NH₃absorption heat transformer system is similar to that of NaSCN/NH₃ system,but its GTL is higher and it can provide greater system temperature rise.