Direct drive refrigerant screw compressor with refrigerant lubricated bearings

A refrigerant system comprising:

• a condenser;
• and
• a direct-drive refrigerant screw compressor, comprising:
• a housing;
• a compression chamber in the housing;
• a pair of rotors including first and second rotors, each of the first and second rotors of the pair of rotors being rotationally disposed in the compression chamber and including an outer surface with a screw-geared profile;
• wherein, for each of the first and second rotors, the compressor includes:
• a plurality of bearing packs disposed within a respective plurality of bearing chambers;
• a working fluid disposed within each of the plurality of bearing chambers for providing oil-free lubrication to the plurality of bearing packs;
• a plurality of bearing lubrication ports extending through the housing and into each of the plurality of bearing chambers, and configured for injecting the working fluid into each of the plurality of bearing chambers when the compressor is running;
• and
• a condenser conduit fluidly connecting condenser to the plurality of bearing lubrication ports,
• wherein the plurality of bearing chambers includes a forward bearing chamber and an aft bearing chamber;
• and
• the plurality of bearing lubrication ports includes, for directing the working fluid into the respective plurality of bearing chambers:
• for the first rotor, a first forward bearing lubrication port and a first aft bearing lubrication port;
• and
• for the second rotor, a second forward bearing lubrication port and a second aft bearing lubrication port, and
• wherein the plurality of bearing lubrication ports includes a respective plurality flow control orifices to reduce a flow volume or rate from a condenser, wherein the respective plurality flow control orifices are defined in the compressor housing.

A method of directing working fluid in a direct-drive refrigerant screw compressor, wherein for each of first and second rotors of a pair of rotors in the compressor, the method comprises:

• receiving working fluid at a plurality of bearing lubrication ports in a housing of the compressor, wherein the working fluid is oil-free;
• and
• directing the working fluid from the plurality of bearing lubrication ports to a plurality of bearing chambers;
• and
• when the compressor is running, lubricating a plurality of bearing packs in the respective plurality of bearing chambers with the working fluid,
• wherein the plurality of bearing chambers includes a forward bearing chamber and an aft bearing chamber;
• and
• the plurality of bearing lubrication ports includes, for directing the working fluid into the respective plurality of bearing chambers:
• for the first rotor, a first forward bearing lubrication port and a first aft bearing lubrication port;
• and
• for the second rotor, a second forward bearing lubrication port and a second aft bearing lubrication port, and
• wherein the plurality of bearing lubrication ports includes a respective plurality flow control orifices to reduce a flow volume or rate from a condenser, wherein the respective plurality flow control orifices are defined in the compressor housing, and
• the method further comprises injecting the working fluid into a forward bearing chamber from the first and second forward bearing lubrication ports and an aft bearing chamber from the first and second aft bearing lubrication ports.