Abstract: A centrifugal compressor assembly includes two centrifugal compressor stages, a diffuser duct, a plurality of collection chambers, inlet and outlet tubing, and a built-in electrical motor between the stages. The centrifugal compressor assembly is used in a refrigerating system. The electrical motor includes a rotor positioned with the compressor stage rotors on one shaft mounted on gasodynamic bearings, with the stator fixed inside the motor housing, forming a cooling skirt. The cooling skirt for the stator is formed by lengthwise slots on the surface of the stator in contact with the housing, with the ends of the slots being connected to annular grooves on the internal surface of the motor housing. Each of the annular grooves is connected to coolant feed and discharge ducts.

Abstract: The present invention provides a two-stage centrifugal compressor. The compressor of this invention has a simplified refrigerant passage structure and effectively cools its electric motor in addition to bearing parts using an existing refrigeration cycle without having another external cooling unit. This compressor thus reduces a consumption of electric power, and improves the operational performance and operational efficiency of a refrigeration system. In the two-stage centrifugal compressor of this invention, a plurality of internal fluid passages is regularly formed on the internal surface of the upper and lower end portions of an external housing so as to allow first and second compression parts to communicate with each other through the interior space of the external housing.

Abstract: A refrigerating system has a condenser, an evaporator, and a two-stage centrifugal compressor assembly with an electric motor provided with a cooling system. A condenser inlet is connected to a compressor assembly outlet, while a condenser outlet is connected via first and second choke elements to an inlet of the evaporator and to the cooling system. The evaporator outlet communicates with the compressor assembly inlet, and the cooling system outlet communicates with the inlet of the second stage of the assembly. The cooling system is provide with a cooling skirt having a cavity of the cooling system lying between a stator and a housing. The refrigerating system has a separator vessel, a recuperative heat exchanger, and a heat-regulating valve controlled by the coolant pressure and temperature at the cooling skirt inlet, and also fitted in series with the separator vessel in the line connecting the condenser inlet to the evaporator. The separator vessel is connected by a gas phase to the coolant feed duct.