INVESTIGATION OF FLOW FIELD CHARACTERISTICS USING CFD IN THE AIR-OIL SEPARATOR OF AN OIL-FLOODED ROTARY SCREW COMPRESSOR

Oil-flooded rotary screw compressors are essential components in a wide range of industries, including commercial and industrial sectors involved in gas processing and refrigeration. Improving their energy efficiency is crucial, primarily by reducing energy losses. The overall efficiency of a compressor is determined by the combined efficiencies of its subsystems. The air-oil separator subsystem experiences the highest friction and pressure drop. Two key factors in optimizing the design of the air-oil separator are maximizing air-oil separation efficiency and minimizing the system's pressure drop. This study uses computational fluid dynamics (CFD) simulations to assess the performance of an air-oil separator within a rotary screw compressor system. The separator is modeled as a tangential inlet cyclone, a widely used design for primary separation. Practically, oil management is multidimensional problem and it is crucial to control the oil carryover for better efficiency, environmental impact, and operational and running cost of compressor. This study is important as to reduce the oil carryover oil management in the separator which is depending on oil flow in air-oil separator, scavenge flow, and orifice sizing. To accurately represent the domain flow within the separator, the finite volume discretization method is applied. Given the highly turbulent and swirling nature of the flow, the Reynolds stress model (RSM) is selected as the turbulence model, which enhances the accuracy of predictions for both air-oil separation efficiency and pressured characteristics. The CFD results show a primary separation efficiency (η) of 88.63%.