Abstract: A high-pressure fan comprising a blade wheel (3, 4), a fan housing (5, 6) surrounding the blade wheel and an electric motor (1) to operate the blade wheel. To eliminate the problems related to the mounting of the blade wheel, the blade wheel (3, 4) at least mainly consists of light carbon fiber based composite material and is directly mounted on the shaft (2) of the electric motor.

Abstract: A mechanical vapor recompression fan comprises a blade wheel and an electric motor to operate the blade wheel. The blade wheel at least mainly consists of carbon-fibre-based composite material and is mounted directly on the shaft of the blade wheel, and the tips of the blades of the blade wheel are provided with an erosion shield.

Abstract: Mixing section for outdoor air and return air in an air-conditioning apparatus, the mixing section being positioned between a supply duct supplying outdoor air into a room and a return duct removing exhaust air from the room for mixing outdoor air and return air. The supply and return ducts comprise adjusting devices for adjusting the air flows. To control the air flows at different mixing ratios and to make the mixing more efficient, guides are provided after the adjusting devices of both the supply device and the return device in a mixing space so as to divide the air flows passing through the adjusting devices into a plurality of separate interlapping air jets crossing each other.

Abstract: A ventilation system for a multi-storey building, which system comprises a ventilation apparatus mounted on a roof and provided with fans for generating an inlet air flow and a distributing channel for supplying the inlet air flow to various intermediate levels of the building. A service shaft of the building serves as an inlet air flow channel, which shaft forms a flow path for the inlet-air flow directed from the fans downwards, whereby the service shaft has deflecting means for passing a part of the air flow to each intermediate level of the building.