Analysis of molecular influence factors on the properties of refrigerant-lubricant mixtures

• Applicant: Professorin Dr.-Ing. Gabriele Raabe
• Subject Area: Technical Chemistry ; Technical Thermodynamics
• Term: from 2019 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 434193542

The aim of this project is a detailed understanding of the molecular mechanism of refrigerant-lubricants interactions, which is of fundament importance and high topicality for the development of efficient HVAC&R systems. For the first time, a systematic analysis of the fundamental interaction mechanisms between different current refrigerants and varying lubricants structures will be performed by molecular simulations.Based on fundamental studies of refrigerant solubility in lubricants, an approach for an adaptive optimization of the alchemical pathwaywill be sytematically extended to allow for efficient and reliable solubility simulations for solvents with higher molecular weight and complex molecular structures. Another subject of the project is a systematic simulation study on the solubilities, viscosities and solvation structures of refrigerant-lubricants mixtures. To allow for an analysis on the impact of different characteristic molecular properties, diverse refrigerants (R-1234yf, HCFO-1233yd(E), R-32, CO2) as well as pentaerythritol ester lubricants with varying molecular structures (PEC4, PEC8, PEB8) will be considered in the study.Based on the simulation results a detailed analysis on the relation of molecular interactions and structures in mixture and the resulting properties such as solubility and viscosity will be performed to identify the relevant molecular interaction pattern in refrigerant-lubricant pairs.The results of the project will provide the scientific basis for the development of future refrigerant-lubricant pairs for sustainable HVAC&R systems. Furthermore, the project will illustrate the use of molecular simulations to evaluate new refrigerant-lubricant-systems, and its potential to be developed towards a method for a computer based screening and knowledge based development of future potential lubricants.

• DFG Programme: Research Grants