Abstract: A gasdynamic arrangement for a multi-stage centrifugal turbomachine, such as a two-stage compressor, comprising two coaxial impellers assembled on a common shaft with axial intake ports and radial peripheral discharge zones, the intake ports of the two impellers preferably pointing away from each other; a cylindrical vessel concentrically housing the impellers and the intake duct; a partition wall between the two impellers having a first and a second group of apertures; a first array of curved ducts conveying the flow from the first impeller discharge zone to the first group of apertures in the partition wall, the flow further passing through a chamber in the vessel to the intake port of the second impeller, and a second array of curved ducts conveying the flow from the second impeller discharge zone to the second group of apertures in the partition wall, the flow further going to the discharge port, the two flows bypassing each other in opposing directions at the partition wall.

Abstract: A method is provided for improving the performance of a heat-pump installation for making ice operating on the principle of mechanical water vapor compression. The installation comprises an evaporator-freezer chamber communicating with a compressor chamber having a centrifugal compressor unit. The method comprises a) providing a first droplet separator of the louver type between the evaporator-freezer chamber and the compressor chamber, for primary separation of the coarser droplets; b) providing a second droplet separator of the knitmesh type downstream of the first droplet separator, for secondary separation of the remaining fine spray, and c) providing a continuous or intermittent spray of a dilute solution of a highly water-soluble inorganic salt in counter-current to the vapor flow from a plurality of spray nozzles located between the first and the second droplet separators and facing the first droplet separator.