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상용 극저온 냉동기를 예냉기로 채택한 수소액화 시스템의 성능해석
김승현(Seung Hyun Kim),장호명(Ho Myung Chang),강병하(Byung Ha Kang) 한국수소및신에너지학회 1998 한국수소 및 신에너지학회논문집 Vol.9 No.2
Thermal analysis on a Linde-Hampson hydrogen liquefaction system using cryogenic refrigerators as precooling has been carried out. Three commercially available models of cryogenic refrigerators, such as CTI 1020CP, CVI CGR009 and CVI CGR011, are considered in the performance analysis. The effect of ortho-para conversion process during hydrogen liquefaction is also studied in detail. The results obtained indicate that the optimal hydrogen mass flow rate and the optimal compressed pressure exist for the maximum hydrogen liquefaction rate. The optimal compressed pressure is increased in the range of 80-120 bar with an increase in the hydrogen mass flow rate. It is also found that better performance could be obtained with a cryogenic refrigerator, which produces high cooling capacity at precooling temperature in the range of 80-100 K.
과냉 액체질소용 저온용기의 증기 공간에서 유리기포의 단열성능
김도헌(Do-heon Kim),김민지(Min-jee Kim),장호명(Ho-Myung Chang) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
An experiment is performedto demonstrate the feasibility of powder insulation in the vapor space above liquid nitrogen for HTS (high temperature superconductor) power applications. Recently, we have proposed this unique insulation technique and tbiswork is the first step to quantify the insulation performance. A liquid-nitrogen container surrounded by vapor spaceis cooled in a cryostat by coldhead of a GM cryocooler, and the heal leak in steady state is measured from the refrigeration capacity of the cryocooler and a precisely controlled heater attached on the coldhead. The same procedure is repeated when the vapor spaced is filled with the proposed powder. The experimental results show that the commercially available glass bubbles in the nitrogen-helium gas mixture for subcooled liquid nitrogen are very effective in reducing the heat leak, mainly because they obstruct the thermal radiation and the natural convection.