A positive displacement expander with an operating fluid chamber of expansive volume regulated by a shifting head. The shifting head may enhance rotation of a housing utilized to rotate a shaft for providing work to any of a variety of power retrieval devices. Additional efficiencies may also be realized through unique hydraulic layouts for circulating of the operating fluid from a heat exchanger, through the rotary device and to a cold exchanger for continuous operating of the rotary device.

A multistage compression system uses refrigerant and oil. The multistage compression system includes a low-stage compressor that compresses the refrigerant, a high-stage compressor that further compresses the refrigerant compressed by the low-stage compressor, and an oil return pipe that returns the oil discharged by the high-stage compressor or the oil in the high-stage compressor to the low-stage compressor. The low-stage compressor has a rotary compression part that compresses the refrigerant, a motor that drives the compression part, and a container housing the compression part and the motor. The motor is disposed above the compression part. The oil return pipe is connected to a space below the motor inside the container.

A positive displacement expander with an operating fluid chamber of expansive volume regulated by a shifting head. The shifting head may enhance rotation of a housing utilized to rotate a shaft for providing work to any of a variety of power retrieval devices. Additional efficiencies may also be realized through unique hydraulic layouts for circulating of the operating fluid from a heat exchanger, through the rotary device and to a cold exchanger for continuous operating of the rotary device.

A multistage compression system uses refrigerant and oil. The multistage compression system includes a low-stage compressor that compresses the refrigerant, a high-stage compressor that further compresses the refrigerant compressed by the low-stage compressor, and an oil return pipe that returns the oil discharged by the high-stage compressor or the oil in the high-stage compressor to the low-stage compressor. The low-stage compressor has a rotary compression part that compresses the refrigerant, a motor that drives the compression part, and a container housing the compression part and the motor. The motor is disposed above the compression part. The oil return pipe is connected to a space below the motor inside the container.

A rotary piston compressor for compressing gas, in particular carbon dioxide, in which a side wall face of a housing side wall and a respective planar sealing face of a respective housing cover enclose a working chamber and a rotary piston is rotatably mounted in the working chamber on an eccentric. A respective planar-seal receiving channel is formed in the piston bases of the rotary piston and a planar seal is arranged in each of the planar-seal receiving channels. To press the seal surface of the respective planar seal against the respective planar sealing face, lateral-surface openings in the piston lateral surface of the rotary piston have a pressure-transmitting connection to the respective planar-seal receiving channel via pressure leadthrough lines, formed inside the rotary piston and each open into the respective planar-seal receiving channel on a side of the respective planar seal facing away from the seal surface.

A rotary piston compressor for compressing gas, in particular carbon dioxide, in which a side wall face of a housing side wall and a respective planar sealing face of a respective housing cover enclose a working chamber and a rotary piston is rotatably mounted in the working chamber on an eccentric. A respective planar-seal receiving channel is formed in the piston bases of the rotary piston and a planar seal is arranged in each of the planar-seal receiving channels. To press the seal surface of the respective planar seal against the respective planar sealing face, lateral-surface openings in the piston lateral surface of the rotary piston have a pressure-transmitting connection to the respective planar-seal receiving channel via pressure leadthrough lines, formed inside the rotary piston and each open into the respective planar-seal receiving channel on a side of the respective planar seal facing away from the seal surface.