Abstract: The invention relates to a method of refrigerant level monitoring in a refrigerant circuit of an air-conditioning or heat-pump system having a compressor and a refrigerant which may, depending on the operating point, be operated in the supercritical range. The method includes standstill level monitoring with the compressor switched off and/or in-operation level monitoring with the compressor switched on. In the case of in-operation level monitoring, the refrigerant overheat (dTü) at the evaporator is registered and, in the event of excessive overheat, it is concluded that there is underfilling. At a standstill, the pressure and temperature of the refrigerant are registered, and it is concluded that there is an improper refrigerant filling level if the pressure (pKM) lies below a minimum pressure value (pmin) or the temperature (TKM) lies above a maximum saturation temperature value (TS) with the pressure being outside a predefinable intended pressure range ([pu,po]).

Abstract: The invention relates to a serpentine heat exchanger having a first serpentine tube block (12a) comprising one or more adjacent first serpentine tube sections with parallel through-flow and a second serpentine tube block (12b) disposed behind the first and comprising one or more adjacent second serpentine tube sections with parallel through-flow. According to the invention, at least one of the second serpentine tube sections is connected in series for flow purposes via a diversion section (10, 11) to a first serpentine tube section lying adjacent thereto.

Abstract: A heat-exchanger tube block is disclosed having at least two header tubes (6, 7), which are C-shaped in cross section and each of which has a continuous longitudinal slot (10, 11). Flat tubes (2a, 2b) are inserted into the header-tube longitudinal slots. A cover-plate element (12) is provided which has a plurality of C-shaped openings and is fitted over one end of the at least two header tubes, so that the header tubes respectively fit into one of the openings and are secured in a fluid-tight manner. The tube-block can be used, for example, in an evaporator of CO2 air-conditioning installations for a motor vehicle.

Abstract: A heat-exchanger tube block is disclosed having at least two header tubes (6, 7), which are C-shaped in cross section and each of which has a continuous longitudinal slot (10, 11). Flat tubes (2a, 2b) are inserted into the header-tube longitudinal slots. A cover-plate element (12) is provided which has a plurality of C-shaped openings and is fitted over one end of the at least two header tubes, so that the header tubes respectively fit into one of the openings and are secured in a fluid-tight manner. The tube-block can be used, for example, in an evaporator of CO2 air-conditioning installations for a motor vehicle.

Abstract: The invention relates to a method for forming at least one flat-tube insertion slot in a header tube. A sawcut is introduced into the header tube during a sawing step, and the slot is configured, during a subsequent punching step, by means of a slot punch, which punches into the region of the sawcut. A rimmed opening can be configured during the punching step by using a slot punch with a larger width and/or length relative to the sawcut. The sawcut is preferably introduced to a depth less that the wall thickness of the header tube. The respective web region(s) between chamber of a multi-chamber header tube can be compressed during the punching operation to a level lower than that of a header-tube wall region functioning as a flat-tube insertion stop, in order to form a chamber-connecting duct.

Abstract: The invention relates to a method of refrigerant level monitoring in a refrigerant circuit of an air-conditioning or heat-pump system having a compressor and a refrigerant which may, depending on the operating point, be operated in the supercritical range. The method includes standstill level monitoring with the compressor switched off and/or in-operation level monitoring with the compressor switched on. In the case of in-operation level monitoring, the refrigerant overheat (dTü) at the evaporator is registered and, in the event of excessive overheat, it is concluded that there is underfilling. At a standstill, the pressure and temperature of the refrigerant are registered, and it is concluded that there is an improper refrigerant filling level if the pressure (pKM) lies below a minimum pressure value (pmin) or the temperature (TKM) lies above a maximum saturation temperature value (TS) with the pressure being outside a predefinable intended pressure range ([pu,po]).

Abstract: The invention relates to a serpentine heat exchanger having a first serpentine tube block (12a) comprising one or more adjacent first serpentine tube sections with parallel through-flow and a second serpentine tube block (12b) disposed behind the first and comprising one or more adjacent second serpentine tube sections with parallel through-flow. According to the invention, at least one of the second serpentine tube sections is connected in series for flow purposes via a diversion section (10, 11) to a first serpentine tube section lying adjacent thereto.