In this study, hydrogen liquefaction equipment by direct cooling using the Gifford-McMahon (GM) refrigerator was designed and setup. Numerical analysis using the commercial software, FLUENT 6.1 was carried out to design an effective insulation system for the liquefaction vessel. From the calculated heat transfer rate of designed insulation system and the predicted vaporizing behavior of liquefied hydrogen, the propriety of heat-resistant efficiency was estimated. Cooling test without load, hydrogen liquefaction experiments were conducted to investigate the performance of the developed equipment. In the case of the cooling without load, temperature of GM refrigerator was lowered to 24 K at the 1ststage and 7 K at the 2ndstage, in the steady state. The Cooling test results indicated that cooling performance was excellent. It was found that the hydrogen started to be liquefied at 217.9 kPa and 23 K by observing the liquid level meter and temperature distribution in the liquefaction vessel. The liquefaction rate was measured at an average of 0.5 L/hr.

본 연구에서는 Gifford-McMahon (GM) 냉동기를 이용하여 직접냉각에 의한 수소액화장치를 개발하였다. 액화용기의 효율적인 단열시스템 설계를 위해 상업용 열유체유동 소프트웨어인 FLUENT 6.1을 이용하여 단열시스템의 열차폐 효율에 대한 전산해석을 수행하였으며 이를 통해 설계된 단열시스템의 열전달률을 도출하고 액체수소의 기화거동을 예측함으로써 열차폐효율의 적정성을 검증하였다. 개발된 수소액화장치의성능실험을 위해 무부하 상태에서의 냉각시험을 거쳐 수소액화실험을 수행하였다. 무부하 냉각의 경우 정상상태 도달시 냉동기 1단의 온도는 24 K, 2단은 7 K까지 하강됨으로써 우수한 냉각성능을 나타내었다. 또한 수소주입시 냉동기 작동 후 액화용기의 액위계 및 온도변화 거동을 관찰함으로써 액화조건 217.9 kPa, 23 K에서 정상적인 수소액화가 이루어졌음을 확인하였으며, 이때의 수소액화량은 평균 0.5 L/hr로 측정되었다.