The heat transfer from the refrigerant and oil mixture in oil separator to the environment.

Gaseous refrigerant and liquid lubricant oil mixture circulates inside an oil separator of refrigeration or heat pump systems. Lubricant oil in this mixture sometimes hits the wall, thus oil is separated from the refrigerant flow in the oil separator. Because of the high temperature of the mixture, heat is transferred to the environment, and this heat loss affects separation phenomena and the total system efficiency. In this study, the circulation phenomenon of oil separator and the heat transfer rate from vertical and horizontal pipes to the environment are analyzed numerically through CFD, and through these data, the relation of charge level of lubricant oil in compressor and heat loss are investigated. R410A and polyvinylether (PVE) are used as refrigerant and lubricant oil, respectively. The key components of cyclone are body diameter, body height, circulation speed, and other dimensions of the cyclone. The circulation speed of cyclone is affected by mass flow rate (MFR) and inlet diameter. The performance of the cyclone is affected by liquid circulation ratio (LCR). In this study, therefore, we analyzed heat transfer of vertical and horizontal pipes with various MFR and LCR to apply to real phenomena of oil separators. These analyzing is very fundamental to measure heat loss of oil separator with respect to the ratio of refrigerant and oil. As the body diameter and height become greater, the heat transfer amount grows bigger. As LCR increases, the same phenomena are expected. These results are useful to design an optimal oil separator and improve the heat transfer performance of refrigeration or heat pump systems.