Development of cold compressors for a 500 W@2 K superfluid helium refrigeration system

•The first self-designed 500 W@ 2 K superfluid helium system including three cold compressors was operated stably in China.•Measuring the enthalpy difference between inlet and outlet helium gas can obtain the static heat leakages of cold compressors.•Reducing external heat leakages enhanced the isentropic efficiencies of cold compressors obviously.