| Absorption refrigeration system is widely concerned because of its effective utilization of low-grade heat energy in providing refrigeration capacity.Traditional absorption refrigeration systems are limited in industrial applications due to refrigeration medium faults such as low-temperature crystallization,high-temperature corrosion,and efficiency degradation via distillation.Ionic liquid is a kind of room temperature molten salt that has the potential to become a refrigerant absorber because of its very low vapor pressure,strong thermal stability,non-corrosive properties,and other benefits.To build a new absorption refrigeration working pair with H2O,a hydrophilic dual amino-functionalized ionic liquid[aP4443][Gly]（3-aminopropyl tributyl phosphonium glycinate）was used in this investigation.The physical parameters of the H2O-[aP4443][Gly]binary mixture and it’s potential as an absorption refrigeration working pair were investigated as follows:（1）Two kinds of dual amino-functionalized ionic liquid[aP4443][Gly]and[aP4443][Ala]（3-aminopropyl tributyl phosphonium L-α-aminopropionic acid salt）were selected.At normal temperature,the density of[aP4443][Gly]aqueous solution was determined experimentally.Molecular dynamics was used to model the density and viscosity of two types of ionic liquids and their aqueous solutions.The simulation findings reveal that diamino functionalized ionic liquids have a larger viscosity than unfunctionalized ionic liquids,however,H2O may significantly lower the viscosity of the solution.It was found that there was a strong interaction between anions（[Gly]-and[Ala]-）and water molecules in the two kinds of ionic liquids,and the interaction was stronger when the concentration of water in the system was lower.Comparing the simulation results of two aqueous solutions of ionic liquids,it is found that the interaction between glycine ion（[Gly]-）and water is stronger than that of alanine ion（[Ala]-）.（2）The eNRTL model was developed based on the vapor and liquid equilibrium data of the H2O-[aP4443][Gly]binary mixture to forecast the vapor pressure parameters of the H2O-[aP4443][Gly]binary mixture over the entire concentration range.The polynomial of specific heat capacity of the binary mixture was fitted using the specific heat capacity data of H2O-[aP4443][Gly].The thermodynamic excess property of the binary mixture was simulated.The results demonstrate that theγ1has strong negative deviations from Raoult’s law,which becomes stronger as the temperature drops,indicating that[aP4443][Gly]has strong hydrophilicity and its aqueous solution has the potential to be employed as the ARS working pair.（3）Based on the thermodynamic properties models of H2O-[aP4443][Gly]binary mixture and the first laws of thermodynamics,the single-effect ARS simulation of the new working pair was carried out.The simulation results reveal that under the conditions of Tg=373.15 K,Ta=303.15 K,Tc=313.15 K,Te=288.15 K,the COP of the refrigeration system with the new working pair（0.736）is higher than that of the NH3-H2O system（0.646）but slightly lower than that of the H2O-Li Br system（0.780）.The influence of each component’s temperature on the system’s refrigeration performance was investigated.By continuously increasing Tgit can be found that COP decreases gently with the increase of temperature,which leads to the system still maintaining a higher COP in the area with higher temperature（when Te=288.15 K and Tg=483.15 K,COP=0.6154）due to the high-temperature stability and specific heat capacity of H2O-[aP4443][Gly],indicating that the novel working pair has the potential to be used in multi-effect absorption refrigeration cycles and refrigeration cycles driven by the high-temperature heat source. |
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