抄録
In recent years there arises growing demand of helium liquefaction refrigerators for the magnetic resonance imaging systems, magnetically levitated vehicles and other systems using superconducting magnet. From this background, a small size, scroll type of hermetic helium compressor capable of compressing helium gas to the pressure ratio of 20 in a single stage is developed. Main features of this compressor are as follows.
1) Discharge capacity can be varied from 7 to 20 Nm3/h by changing driving motor frequency from 30 to 80 Hz.
2) The overall adiabatic efficiency showed 72%∼79% under the pressure ratio range of 11∼20 at 60 Hz using oil injection cooling device.
