Lubricant management in an HVACR system
A heating, ventilation, air conditioning, and refrigeration (HVACR) system is disclosed. The HVACR system includes a compressor, a condenser, and an evaporator fluidly connected to form a refrigerant circuit. A lubricant return line is fluidly connected to the compressor and to the evaporator. A pressure difference between the compressor and the evaporator induces a fluid flow of lubricant from the evaporator to the compressor.
1 . A lubricant management method for a screw compressor in a heating, ventilation, air conditioning, and refrigeration (HVACR) system, comprising:
forming a lubricant inlet port in a location of the screw compressor of the HVACR system, and
fluidly connecting the lubricant inlet port to be in fluid communication with a lubricant supplying component of the HVACR system by connecting an outlet end of a lubricant return line to the screw compressor and connecting an inlet end of the lubricant return line to the lubricant supplying component of the HVACR system,
wherein the lubricant inlet port is disposed in a sealed bearing cavity of the screw compressor, wherein the sealed bearing cavity is at least partially housed by a bearing housing, a lubricant pool is formed in the sealed bearing cavity,
wherein a lubricant outlet port of the sealed bearing cavity is fluidly connected to a component of the HVACR system having a lower pressure than a first pressure at the lubricant inlet port such that a second pressure in the sealed bearing cavity is lower than the first pressure at the lubricant inlet port.
2 . The method of claim 1 , further comprising flashing refrigerant in the lubricant by having the second pressure in the sealed bearing cavity being lower than the first pressure at the lubricant inlet port to increase viscosity of the lubricant.
3 . The method of claim 1 , wherein the sealed bearing cavity is configured such that the lubricant outlet port is positioned at a height to create a volume of lubricant to lubricate radial and thrust bearings of the screw compressor.
4 . A heating, ventilation, air conditioning, and refrigeration (HVACR) system, comprising:
a screw compressor including a lubricant inlet port;
a condenser;
an evaporator fluidly connected to form a refrigerant circuit; and
a lubricant return line connected at an outlet end to the lubricant inlet port of the screw compressor and connected at an inlet end to a liquid level in a lubricant supplying component of the HVACR system,
wherein the lubricant inlet port is disposed in a sealed bearing cavity of the screw compressor, wherein the sealed bearing cavity is at least partially housed by a bearing housing, the sealed bearing cavity includes a lubricant pool, wherein a lubricant outlet port of the sealed bearing cavity is fluidly connected to a component of the HVACR system having a lower pressure than a first pressure at the lubricant inlet port such that a second pressure in the sealed bearing cavity is lower than the first pressure at the lubricant inlet port.
5 . The HVACR system of claim 4 , wherein the second pressure in the sealed bearing cavity is lower than the first pressure at the lubricant inlet port such that refrigerant in the lubricant is flashed to increase viscosity of the lubricant.
6 . The HVACR system of claim 4 , wherein the sealed bearing cavity is configured such that the lubricant outlet port is positioned at a height to create a volume of lubricant to lubricate radial and thrust bearings of the screw compressor.
7 . The HVACR system of claim 4 , wherein the lubricant inlet port includes a line that extends through the bearing housing.
8 . The HVACR system of claim 4 , wherein an end of a shaft, at least one radial bearing, a thrust bearing, and the lubricant pool are included within the sealed bearing cavity,
the at least one radial bearing and the thrust bearing are housed at least partially in the bearing housing.
9 . The HVACR system of claim 8 , wherein the thrust bearing, when compared to the at least one radial bearing, is relatively closer to a compression chamber of the screw compressor.
10 . The HVACR system of claim 8 , wherein the lubricant outlet port is positioned at a height to create the lubricant pool to lubricate the at least one radial bearing and the thrust bearing,
the lubricant outlet port is disposed higher than the lubricant pool.
11 . The HVACR system of claim 10 , wherein a lubricant outlet line extends from the lubricant outlet port to an outlet of the lubricant outlet line.