Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A centrifugal compressor assembly for compressing refrigerant in a 250-ton capacity or larger chiller system comprising a motor, preferably a compact, high energy density motor or permanent magnet motor, for driving a shaft at a range of sustained operating speeds under the control of a variable speed drive. Another embodiment of the centrifugal compressor assembly comprises a mixed flow impeller and a vaneless diffuser sized such that a final stage compressor operates with an optimal specific speed range for targeted combinations of head and capacity, while a non-final stage compressor operates above the optimum specific speed of the final stage compressor. Another embodiment of the centrifugal compressor assembly comprises an integrated inlet flow conditioning assembly to condition flow of refrigerant into an impeller to achieve a target approximately constant angle swirl distribution with minimal guide vane turning.

Abstract: 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.

Abstract: An improved bearing housing of a rotary screw compressor is described. The bearing housing is generally shorter than a convention bearing housing. The bearing housing can be configured to enclose and support radial bearings of the screw compressor. The bearing housing can be configured not to enclose axial bearings of the screw compressor in an axial direction.

Abstract: A coaxial economizer for use in a chiller system comprising an inner housing and an outer housing having a common longitudinal axis. The outer housing has an inlet for receiving a fluid from a upstream compressor stage of a multistage compressor and an outlet for conveying a fluid to a downstream compressor stage of a multistage compressor. A flow chamber forms a fluid flow path about the inner housing. A flash chamber is coterminous with the flow chamber and flashes fluid in a liquid state to a gas state. A flow passage between said flash chamber and the flow chamber for conveying a flashed gas from the flash chamber to the flow chamber; wherein the flashed gas conveyed from the flash chamber and the fluid received from the inlet of the outer housing mix along the fluid flow path toward the outlet of the outer housing.

Abstract: A centrifugal compressor assembly for compressing refrigerant in a 250-ton capacity or larger chiller system comprising a motor, preferably a compact, high energy density motor or permanent magnet motor, for driving a shaft at a range of sustained operating speeds under the control of a variable speed drive. Another embodiment of the centrifugal compressor assembly comprises a mixed flow impeller and a vaneless diffuser sized such that a final stage compressor operates with an optimal specific speed range for targeted combinations of head and capacity, while a non-final stage compressor operates above the optimum specific speed of the final stage compressor. Another embodiment of the centrifugal compressor assembly comprises an integrated inlet flow conditioning assembly to condition flow of refrigerant into an impeller to achieve a target approximately constant angle swirl distribution with minimal guide vane turning.

Abstract: A centrifugal compressor assembly for compressing refrigerant in a 250-ton capacity or larger chiller system comprising a motor, preferably a compact, high energy density motor or permanent magnet motor, for driving a shaft at a range of sustained operating speeds under the control of a variable speed drive. Another embodiment of the centrifugal compressor assembly comprises a mixed flow impeller and a vaneless diffuser sized such that a final stage compressor operates with an optimal specific speed range for targeted combinations of head and capacity, while a non-final stage compressor operates above the optimum specific speed of the final stage compressor. Another embodiment of the centrifugal compressor assembly comprises an integrated inlet flow conditioning assembly to condition flow of refrigerant into an impeller to achieve a target approximately constant angle swirl distribution with minimal guide vane turning.

Abstract: An assembly includes a composite metal-polymer bushing having an outer metal layer with an inner surface, metal particles sintered to the inner surface, a polymer material between the metal particles, a finished interior surface collectively defined by the polymer material and exposed portions of the metal particles, a plurality of interstices formed between the metal particles and the polymer material, and a plurality of ridges defined by the polymer material that protrude above the metal particles. The ridges occupy at least about 8% of the area of a cylindrical reference surface nominally coinciding with the finished interior surface. The assembly also includes a crankshaft having a journal at least partially received within the bushing and supported by the finished interior surface. The journal is polished to a surface finish of about 0.1 microns or less to reduce a wear rate of the bushing.

Abstract: A system and method of loading and unloading a compressor in a cooling system. The method includes detecting a temperature, determining a compressor should be turned on/off to supply/stop supplying cooling based on the temperature, turning the compressor on/off, and opening/closing a plurality of valves when the compressor is turned on/off.

Abstract: An assembly includes a composite metal-polymer bushing having an outer metal layer with an inner surface, metal particles sintered to the inner surface, a polymer material between the metal particles, a finished interior surface collectively defined by the polymer material and exposed portions of the metal particles, a plurality of interstices formed between the metal particles and the polymer material, and a plurality of ridges defined by the polymer material that protrude above the metal particles. The ridges occupy at least about 8% of the area of a cylindrical reference surface nominally coinciding with the finished interior surface. The assembly also includes a crankshaft having a journal at least partially received within the bushing and supported by the finished interior surface. The journal is polished to a surface finish of about 0.1 microns or less to reduce a wear rate of the bushing.

Abstract: A centrifugal compressor assembly for compressing refrigerant in a 250-ton capacity or larger chiller system comprising a motor, preferably a compact, high energy density motor or permanent magnet motor, for driving a shaft at a range of sustained operating speeds under the control of a variable speed drive. Another embodiment of the centrifugal compressor assembly comprises a mixed flow impeller and a vaneless diffuser sized such that a final stage compressor operates with an optimal specific speed range for targeted combinations of head and capacity, while a non-final stage compressor operates above the optimum specific speed of the final stage compressor. Another embodiment of the centrifugal compressor assembly comprises an integrated inlet flow conditioning assembly to condition flow of refrigerant into an impeller to achieve a target approximately constant angle swirl distribution with minimal guide vane turning.

Abstract: 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.

Abstract: A centrifugal compressor assembly for compressing refrigerant in a 250-ton capacity or larger chiller system comprising a motor, preferably a compact, high energy density motor or permanent magnet motor, for driving a shaft at a range of sustained operating speeds under the control of a variable speed drive. Another embodiment of the centrifugal compressor assembly comprises a mixed flow impeller and a vaneless diffuser sized such that a final stage compressor operates with an optimal specific speed range for targeted combinations of head and capacity, while a non-final stage compressor operates above the optimum specific speed of the final stage compressor.

Abstract: A centrifugal compressor assembly for compressing refrigerant in a 250-ton capacity or larger chiller system comprising a motor, preferably a compact, high energy density motor or permanent magnet motor, for driving a shaft at a range of sustained operating speeds under the control of a variable speed drive. Another embodiment of the centrifugal compressor assembly comprises a mixed flow impeller and a vaneless diffuser sized such that a final stage compressor operates with an optimal specific speed range for targeted combinations of head and capacity, while a non-final stage compressor operates above the optimum specific speed of the final stage compressor.

Abstract: A method of optimizing the design of a chiller involves placing more emphasis on the chiller's performance at part load than at full load and rating the chiller accordingly. In some embodiments, compressor speed and impeller diameter are chosen to optimize the chiller's performance at part load. With the chosen impeller diameter, operation at full load is then achieved by increasing compressor speed, opening inlet guide vanes, and perhaps sacrificing some efficiency. If necessary, an inverter over speeds the compressor by driving it at a speed beyond that which the compressor would normally run if it were driven at the nominal line frequency of the electrical power feeding the inverter.