13. Air-Condition and Refrigeration

The mixing of refrigerant and refrigerant oil usually occurs in refrigeration compressors, which affects the viscosity and foaming of the oil. In particular, zeotropic refrigerants are composed of two or more components whose equilibrium vapor and liquid phases have different compositions. As a result, the mixing behaviors of zeotropic refrigerant and refrigeration oil are expected to be different from those of pure refrigerant. In this study, the zeotropic refrigerant and refrigerant oil used were R454C refrigerant and polyol ester (POE) oil due to their good compatibility. To investigate the mixing behaviors of R454C and POE, a high-pressure-resistant vessel with mounted transparent glass was used to conduct the experiment. The test conditions for the temperature and the refrigerant mass fraction were varied from 30 to 90 °C and 0 to 1.0, respectively. The solubility of the POE/R454C mixture was measured together with the refractive index. Furthermore, the calculation to obtain the mass of liquid-phase refrigerant in oil was proposed in both cases, with temperatures lower and higher than the refrigerant’s critical temperature.