Molecular simulation on the interaction between polypropylene glycol dimethyl ether and trans-1233zd

Abstract

• Developed the ab initio and MD model for refrigerant-lubricant oil system. • Obtained intermolecular interactions from atomic and electronic level. • Characterized solubility properties, solvation mechanism and structure. Hydrofluoroolefins (HFO) are considered as substitute to HFC refrigerant in the Organic Rankine cycle, however, the lack of studies on HFO refrigerant-lubricant mixtures hampers their further applications. This reported computational work aims to provide guidance for the development of suitable lubricants for new refrigerants. We use ab initio and large scale molecular dynamics (MD) modeling to gain insight into the molecular mechanism of interaction between polypropylene glycol dimethyl ether (PPGDE) and R1233zd(E). The ab initio calculated stable structures, interaction energies and charge distribution analysis indicate that the oxygen atoms in PPGDE and chlorine atom in R1233zd(E) play a major role in the solubility, the calculated interaction energy is -13.97 kJ mol −1 for the most stable configuration; The MD simulated density of R1233zd(E) agrees well with experimental data over a wide range of temperatures and pressures, the obtained cohesive energy density, solubility parameter, Flory−Huggins parameter and radial distribution functions (RDF) allow a characterization of the solubility properties and reveal the solvation mechanism and structure as well, PPGDE molecules begin to be attached to the Cl atoms in R1233zd(E) from the first neighbor shell of radius 2.925 Å.