A head-mountable flow generator is configured to deliver a flow of breathable gas at a continuously positive pressure with respect to ambient air pressure to a patient interface in communication with an entrance to a patient's airways including at least an entrance of the patient's nares, while the patient is sleeping, to ameliorate sleep disordered breathing. The flow generator includes a motor, an impeller assembly and housing that encases the motor and the impeller assembly. The housing is configured to be mounted on the patient's head and comprises an inlet to receive the flow of breathable gas and a pair of opposing outlets to deliver the flow of breathable gas. In addition, the impeller assembly is configured to pressurize the flow of breathable gas received from the inlet, and the housing is configured to convey the pressurized flow of breathable gas through both outlets.

A head-mountable flow generator is configured to deliver a flow of breathable gas at a continuously positive pressure with respect to ambient air pressure to a patient interface in communication with an entrance to a patient's airways including at least an entrance of the patient's nares, while the patient is sleeping, to ameliorate sleep disordered breathing. The flow generator includes a motor, an impeller assembly and housing that encases the motor and the impeller assembly. The housing is configured to be mounted on the patient's head and comprises an inlet to receive the flow of breathable gas and a pair of opposing outlets to deliver the flow of breathable gas. In addition, the impeller assembly is configured to pressurize the flow of breathable gas received from the inlet, and the housing is configured to convey the pressurized flow of breathable gas through both outlets.

A heating, ventilation, air conditioning, and refrigeration (HVACR) system includes a compressor with a gas bearing supplied with compressed gas and a controller. The controller is configured to determine an inlet pressure and outlet pressure of the gas bearing, determine a maximum speed limit based on the inlet pressure and the outlet pressure, and prevent the compressor from operating at a speed that is greater than the maximum speed limit. A method of controlling a compressor includes calculating a maximum speed limit based on an inlet pressure and an outlet pressure of the gas bearing. The method also includes in response to determining that a speed setting is greater than the maximum speed limit, adjusting operation of the compressor such that a speed of the compressor is at or below the maximum speed limit.

A heat transfer circuit includes a compressor, a condenser, an expander, and an evaporator that are fluidly connected together. The compressor includes a housing and a shaft rotatable relative to the housing to compress a working fluid received at a suction inlet, in which the shaft is supported by a gas bearing, and the gas bearing including a bearing housing having a fluid inlet and an outlet. A high pressure gas source is fluidly connected to the fluid inlet of the bearing housing for supplying high pressure fluid to the fluid inlet of the gas bearing such that the gas bearing supports the shaft when the shaft is rotating. A pressure reducer is connected to the outlet of the gas bearing is provided for reducing a vent pressure of the gas bearing.

A method for operating start-up of a compressor train is disclosed. The train includes a driver machine and at least a centrifugal compressor drivingly coupled to the driver machine. The centrifugal compressor in turn includes a plurality of compressor stages and at least a first set of variable inlet guide vanes at an inlet of one of the compressor stages. The method includes at least partly closing the first set of variable inlet guide vanes; when the first set of variable inlet guide vanes is at least partly closed, starting rotation of the centrifugal compressor and accelerating the centrifugal compressor up to a minimum operating speed; opening the at least one set of variable inlet guide vanes to increase the gas flow through the centrifugal compressor once the minimum operating speed has been achieved.

A compressor system includes: a first compressor including a first casing having a cylindrical shape, and a first bundle capable of being inserted into and pulled out from the first casing in an axial direction of the first casing; and a second compressor including a second casing having a cylindrical shape, and a second bundle capable of being inserted into and pulled out from the second casing in an axial direction of the second casing. The first and second compressors are arranged to face each other to cause pullout directions of the respective bundles to be opposite to each other. A maintenance space shareable for insertion and pullout operations of the first bundle and insertion and pullout operations of the second bundle is interposed between the first bundle and the second bundle, and is available for the bundle under the insertion and pullout operations.

A dual impeller includes: a hub configured to rotate about a rotation axis; a plurality of first blades which are disposed on a first surface of the hub along a circumferential direction of the hub; a first shroud which is mounted on the plurality of first blades to cover the plurality of first blades; and a plurality of second blades which are disposed on a first surface of the first shroud along a circumferential direction of the first shroud.

A dual impeller includes: a hub configured to rotate about a rotation axis; a plurality of first blades which are disposed on a first surface of the hub along a circumferential direction of the hub; a first shroud which is mounted on the plurality of first blades to cover the plurality of first blades; and a plurality of second blades which are disposed on a first surface of the first shroud along a circumferential direction of the first shroud.

A centrifugal compressor, including: a housing; a motor assembly disposed in the housing and a motor cavity and a motor shaft located in the motor cavity, the motor shaft having a first end and a second end extending from the motor cavity; a first impeller assembly located at the first end of the motor shaft and provided with a first labyrinth sealing mechanism; a second impeller assembly located at the second end of the motor shaft and provided with a second labyrinth sealing mechanism; a first gas bearing assembly provided between the motor cavity and the first impeller assembly; and a second gas bearing assembly provided between the motor cavity and the second impeller assembly; wherein the first labyrinth sealing mechanism is kept in gas communication with the first gas bearing assembly, and the second labyrinth sealing mechanism is kept in gas communication with the second gas bearing assembly.

A stable discharge pressure of compressed hydrogen gas generated from the electrolysis of water is achieved and maintained at the outlet of a “hybrid” multistage compression system comprising at least a first section comprising at least one centrifugal compressor powered at least in part by electricity generated from at least one renewable energy source and a further section downstream of the first section, wherein the further section comprises at least one reciprocating compressor.