A novel hydrogen turbo-expander with active magnetic bearings and an eddy current brake

Abstract

A cryogenic expander for hydrogen liquefier with active magnetic bearings (AMB) has been designed and will be made and tested. The shaft design and strength review are significant factors for the turbine since it affects the performance and safety of the expander significantly. In order to produce lower temperature hydrogen, the liquefier needs a very small and high-speed turbo-expander. However, there are few studies on expander with both active magnetic bearings and eddy current brakes. In this study, the speed of the turbine is up to 100000 rpm. Its cooling power is about 4kW. The inlet pressure is 1MPa, and the outlet pressure is 0.7MPa. Under this condition, the turbine is designed, and the simulation is done. An eddy current brake which can govern the rotational speed quickly is designed and studied as well.