Filter-type oil separator: When the high-pressure refrigerant gas discharged from the compressor enters the separator, the gas flow rate suddenly decreases and changes direction due to the large flow cross-section. Combined with the filtering effect of several layers of metal wire mesh during intake, the lubricating oil mixed in the refrigerant gas is separated and drips down to collect at the bottom of the container. When the accumulated lubricating oil reaches a certain height, it returns to the compressor crankcase through the automatic oil return valve. During normal operation, the intermittent operation of the float valve causes the oil return pipe to fluctuate in temperature; the pipe is hot when oil is returning and cold when oil is not returning. If the oil return pipe remains consistently cold or hot, it indicates that the float valve has malfunctioned and must be repaired. A manual oil return valve can be used for repair. This type of oil separator has a simple structure, is easy to manufacture, and is widely used, but its oil separation effect is not as good as that of the packing type.
Centrifugal oil separator: Centrifugal oil separators have better oil separation effects and are suitable for large refrigeration systems. The compressor exhaust enters the cylinder tangentially through the oil separator's inlet pipe, then rotates at high speed along the spiral guide vanes and flows from top to bottom. Centrifugal force forces denser oil droplets in the exhaust gas to be separated against the cylinder wall, flowing down and settling at the bottom. Vapor is led out through a perforated plate in the outlet pipe at the center of the cylinder. A float valve is installed on the side of the cylinder; when the oil level rises to the upper limit, the lubricating oil opens the valve core through the float valve, automatically draining oil into the compressor crankcase or oil collector. Some models also have a cooling water jacket outside the oil separator, allowing the mixed gas to be cooled by cooling water and further separated by reducing flow velocity and changing flow direction.
