Abstract: This disclosure relates to a method for operating a combined heat and power device, wherein carbon dioxide as a refrigerant (17) is compressed in a compressor, wherein the carbon dioxide is carried along a refrigerant circuit and routed back to the compressor via a collecting vessel (5). The method is distinguished by the fact that the compressor is lubricated with a lubricant (15) which has a density of more than 1004 g/l, and that a hot gas temperature in the compressor is held below a predetermined value, above which overheating and/or ageing of the lubricant occurs.

Abstract: An air-conditioning system with a refrigerant medium circulating in a refrigerant loop has a variable-stroke compressor with a high-pressure outlet chamber, a drive chamber and an intake suction chamber. A first valve regulates a first flow of refrigerant medium from the high-pressure outlet chamber to the drive chamber, and a second valve regulates a second flow of refrigerant medium from the drive chamber to the intake suction chamber. The first and second valves operate independently of each other under the control of a control unit, and the variable stroke of the compressor is controlled by the first and/or second flow of refrigerant medium.

Abstract: An air-conditioning system with a refrigerant medium circulating in a refrigerant loop has a variable-stroke compressor with a high-pressure outlet chamber, a drive chamber and an intake suction chamber. A first valve regulates a first flow of refrigerant medium from the high-pressure outlet chamber to the drive chamber, and a second valve regulates a second flow of refrigerant medium from the drive chamber to the intake suction chamber. The first and second valves operate independently of each other under the control of a control unit, and the variable stroke of the compressor is controlled by the first and/or second flow of refrigerant medium.

Abstract: A safety device limits the pressure in an axial-piston compressor with variable piston displacement. The compressor has as wobble plate or swash plate whose tilt angle can be variably controlled by the pressure differential between the high pressure in the discharge pressure zone and the pressure in the piston-drive chamber. The safety device consists of a valve arranged in a connector channel between the discharge pressure zone and the pressure zone of the piston-drive chamber. When the discharge pressure exceeds a given pressure limit, the safety device responds by allowing an increased flow of pressure medium from the discharge pressure zone to the piston-drive chamber. The influx of pressure medium into the piston-drive chamber causes a reduction of the tilt angle of the swash plate or wobble plate.