A Study on Stirling Cryocooler for Precooling Hydrogen Liquefier

Korea Institute of Machinery & Materials (KIMM) has developed a high efficient Stirling cryocooler with moving magnet linear compressor for precooling hydrogen liquefier and cooling high temperature superconductor (HTS) devices, such as superconductor cable and superconductor fault current limiters. Hydrogen liquefier and HTS electric devices require cryocooler with cooling capacity of hundred watts to kilowatts at 77 K. The compressor in the Stirling cryocooler uses opposed moving magnet linear motors to drive opposed pistons. High efficient Stirling cryocooler is designed by SAGE-software, manufactured and tested systematically. A cooling capacity of 1 kW at 77 K with an electric input power of 9.6 kW has been analyzed. But prototype test results of the Stirling cryocooler have the cooling capacity of 0.65 kW at 76.8 K with an electric input power of 8.1 kW. And then, 21.5% Carnot COP (Coefficient of performance) of the prototype Stirling cryocooler is achieved. The comparison analysis between SAGE-model and experimental results has shown the direction for further design optimization of the Stirling cryocooler.