Development of High-capacity Single-stage GM Cryocoolers at SHI

Applications including HTS superconducting motor, power transmission line and power generator are usually considered to consume 102 W to 104 W cooling power. Most of those applications are currently using direct liquid nitrogen cooling or Turbo-Brayton cryocoolers. Though having the potential to significantly reduce the cost and space requirement, current commercial GM cryocoolers lack the suitable cooling power which is crucial in HTS applications. Since 2013, Sumitomo Heavy Industries, Ltd. (SHI) has been developing high capacity single stage GM cryocoolers for HTS applications around 80 K. With a conventional scotch-yoke-driven single-displacer GM cryocooler, a cooling capacity of 650 W was achieved with an input power of about 13 kW. To further improve the efficiency, a novel concept, called dual-displacer GM cryocooler has been developed since 2015. In a dual-displacer GM cryocooler, displacers are connected to both ends of the Scotch yoke. Two expansion spaces are constructed by the displacers and cylinders. Helium gas is supplied to and discharged from the upper and the lower expansion spaces with a phase shift of about 180°. In principle, the pressure oscillation amplitude at the compressor side is reduced and thus the overall efficiency of the cryocooler is improved. ... mehrWith a dual-displacer concept, a cooling capacity of 725 W at 80 K was achieved with an input power of 13.8 kW. In a Scotch yoke type GM cryocooler, the driving mechanism becomes heavier and more complicated as the required cooling capacity increases. Recently, SHI has been developing pneumatic GM cryocoolers. As preliminary results, a cooling capacity of 700 W at 80 K was achieved with an input power of 18.0 kW. A summary of the development status of such cryocoolers will be reported in this presentation.