A NOVEL MODELLING APPROACH FOR THERMODYNAMIC DATA OF REFRIGERANT-OIL MIXTURES

DOI: 10.18462/iir.compr.2024.0620

Sekcia: Compressors and oils

Stav prijatia: Abstrakt prijatý

Autori

Abstrakt

Modelling all the necessary thermodynamic properties, especially density, phase behavior, specific heat capacity, entropy, enthalpy, viscosity and thermal conductivity of lubricating oils and - in addition to this - the vapor pressure of refrigerant-oil mixtures in chillers and heat pumps is still a challenge today. Here we propose a new modelling approach based on the material data of the pure oil as described in the manufacturer’s data sheet. For the pure oil, the model achieves an accuracy in the range of the measurement uncertainty. The model is now extended with the help of knowledge of the refrigerant, especially its tabulated properties. With already described mathematical relationships and new approaches of the temperature-concentration behavior of the relevant thermodynamic properties of refrigerant-oil mixtures it is possible to predict these properties.
For an example system (R290-PAG oil), the derivation of the coefficients of the equation to represent the temperature-concentration behavior of the density of the refrigerant-oil system is presented. This estimation is initially made without using additional measurement data from the mixture. A similar approach is presented for the specific heat capacity and the thermal conductivity of the mixture. In a second step, the estimates obtained in this way are concretized with a small amount of measurement data and then compared with the complete measurement. The vapor pressure-viscosity behavior as a function of temperature and concentration (pvT) of a R290-PAG oil mixture is also derived in this way and presented.

Kľúčové slová

Refrigerant-Oil Mixtures, Thermodynamic Properties, pvT, Propane, PAG Oil, Density, Vapor Pressure, Viscosity, Heat Capacity, Thermal Conductivity