A Generic Pump/Compressor Design for Circulation of Cryogenic Fluids

This paper describes the development of a second-generation centrifugal circulator for cryogenic fluids. The circulator is designed to operate over a wide range of flow rate and pressure rise and can be used for the pumping of liquid and compression of vapor at temperatures down to liquid helium (4 K). The machine incorporates self-acting gas journal bearings, a permanent magnet axial thrust bearing, and a variable speed induction motor drive to provide for reliable, maintenance-free operation. The paper will describe design details of the pump. Calculated performance characteristics for a liquid helium pumping application will be presented along with a general discussion regarding limitations of the present system.