A heating, ventilation, air conditioning, and refrigeration (HVACR) system is disclosed. The HVACR system includes a refrigerant circuit. The refrigerant circuit includes a compressor, a condenser, an expansion device, and an evaporator fluidly connected. A controller is electronically connected to the compressor. The controller is configured to prevent the compressor from operating at a speed that is less than a minimum speed limit. A lubricant separator has an inlet fluidly connected between the compressor and the condenser and a plurality of outlets. A first of the plurality of outlets is fluidly connected to the condenser. A second of the plurality of outlets is fluidly connected to one or more components of the compressor to provide a lubricant to the one or more components.

A variable capacity screw compressor comprises a suction port, at least two screw rotors and a discharge port being configured in relation to a selected rotational speed that operates at least one screw rotor at an optimum peripheral velocity that is independent of a peripheral velocity of the at least one screw rotor at a synchronous motor rotational speed for a rated screw compressor capacity. A motor is configured to drive the at least one screw rotor at a rotational speed at a full-load capacity that is substantially greater than the synchronous motor rotational speed at the rated screw compressor capacity. A variable speed drive receives a command signal from a controller and generates a control signal that drives the motor at the selected rotational speed.

A variable capacity screw compressor comprises a suction port, at least two screw rotors and a discharge port being configured in relation to a selected rotational speed that operates at least one screw rotor at an optimum peripheral velocity that is independent of a peripheral velocity of the at least one screw rotor at a synchronous motor rotational speed for a rated screw compressor capacity. A motor is configured to drive the at least one screw rotor at a rotational speed at a full-load capacity that is substantially greater than the synchronous motor rotational speed at the rated screw compressor capacity. A variable speed drive receives a command signal from a controller and generates a control signal that drives the motor at the selected rotational speed.

A screw compressor includes a compressor housing defining a working chamber, the housing including a plurality of bores; a first rotor having helical threads, the first rotor being housed in a first of the plurality of bores; a second rotor having helical threads intermeshing with the helical threads of the first rotor, the second rotor being housed in a second of the plurality of bores; an inlet port that receives a fluid to be compressed; an outlet port that receives a compressed fluid; and an intermediate discharge port disposed between the compression chamber and the outlet port, the intermediate discharge port including a sealing member and a biasing mechanism, fluid flow being prevented between the compression chamber and the intermediate discharge port when in a flow-blocked state, and fluid flow being enabled from the compression chamber through the intermediate discharge port when in a flow-permitted state.

A screw compressor includes a compressor housing defining a working chamber, the housing including a plurality of bores; a first rotor having helical threads, the first rotor being housed in a first of the plurality of bores; a second rotor having helical threads intermeshing with the helical threads of the first rotor, the second rotor being housed in a second of the plurality of bores; an inlet port that receives a fluid to be compressed; an outlet port that receives a compressed fluid; and an intermediate discharge port disposed between the compression chamber and the outlet port, the intermediate discharge port including a sealing member and a biasing mechanism, fluid flow being prevented between the compression chamber and the intermediate discharge port when in a flow-blocked state, and fluid flow being enabled from the compression chamber through the intermediate discharge port when in a flow-permitted state.

A mechanical device includes a working medium, a hot end, a cold end, and first and second volume regulating units. The hot and cold ends are in thermal contact with the working medium during circulation thereof. The first and second volume regulating units are disposed between the hot and cold ends, and are configured to allow passage of the working medium therethrough to perform compression and expansion of the working medium. The volume of the working medium exiting the first volume regulating unit differs from that of the working medium entering the second volume regulating unit. The volume of the working medium entering the first volume regulating unit differs from that of the working medium exiting the second volume regulating unit.

The present invention provides a composition containing a refrigerant having characteristics equal to or higher than those of R23. Specifically, the present invention provides a composition containing a refrigerant, wherein the refrigerant contains (a) at least one perfluorocarbon (PFC) selected from the group consisting of PFC-14, PFC-116, PFC-c216, FFC-218, PFC-c318, and PFC-31-10, and (b) an unsaturated compound.

The present invention provides a composition containing a refrigerant having characteristics equal to or higher than those of R23. Specifically, the present invention provides a composition containing a refrigerant, wherein the refrigerant contains (a) at least one perfluorocarbon (PFC) selected from the group consisting of PFC-14, PFC-116, PFC-c216, FFC-218, PFC-c318, and PFC-31-10, and (b) an unsaturated compound.

A variable capacity screw compressor comprises a suction port, at least two screw rotors and a discharge port being configured in relation to a selected rotational speed that operates at least one screw rotor at an optimum peripheral velocity that is independent of a peripheral velocity of the at least one screw rotor at a synchronous motor rotational speed for a rated screw compressor capacity. A motor is configured to drive the at least one screw rotor at a rotational speed at a full-load capacity that is substantially greater than the synchronous motor rotational speed at the rated screw compressor capacity. A variable speed drive receives a command signal from a controller and generates a control signal that drives the motor at the selected rotational speed. A method for sizing at least two variable capacity screw compressors and a refrigeration chiller incorporating a variable capacity screw compressor are separately presented.

A variable capacity screw compressor comprises a suction port, at least two screw rotors and a discharge port being configured in relation to a selected rotational speed that operates at least one screw rotor at an optimum peripheral velocity that is independent of a peripheral velocity of the at least one screw rotor at a synchronous motor rotational speed for a rated screw compressor capacity. A motor is configured to drive the at least one screw rotor at a rotational speed at a full-load capacity that is substantially greater than the synchronous motor rotational speed at the rated screw compressor capacity. A variable speed drive receives a command signal from a controller and generates a control signal that drives the motor at the selected rotational speed. A method for sizing at least two variable capacity screw compressors and a refrigeration chiller incorporating a variable capacity screw compressor are separately presented.