東大理工学研究所の水素液化機

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As a part of the activities of the research committee for cryogenics of Institute of Science and Technology, two hydrogen liquefiers were developed; one with product rate of liquid hydrogen by 1 liter per hour, and the other larger one by 8 liters per hour. The small liquefier which was developed both as a prototype for the larger one and as a convenient portable liquefier operating from commercial hydogen in cylinder is shown in Fig. 2, and Fig. 3. The regenerative heat exchanger was made by one 1.5×2.5mm high pressure tube and one 2.5×3.5mm low pressure tube soft soldered side by side. To reduce thermal conduction along the tubes, 80% Cu-20%. Ni Cupro-Nickel was used for the material, and the total length of the heat exchanger was 230cm. This worked quite well, producing about 1 liter of liquid hydrogen from a commercial cylinder. The larger liquefier which was constructed to satisfy liquid hydrogen demand of the institute is shown in Fig. 4 and Fig. 5. The capacity of the hydrogen compressor was 30 m^3/hour with operating pressure of 150atm. For most tubes, especially those which work in the temperature range below liquid nitrogen, Cupro-Nickel was used for the material. Fig. 6 shows the cross section of the regenerative heat exchanger which was made from one high pressure and six low pressure tubes soft soldered together. One of the low pressure tubes is to purify the feeded hydrogen gas. The total length of the exchanger was 500cm. The tubes were made of the 80-20 Cupro-Nickel. The level of liquid nitrogen and of hydrogen was measured by Hampson type levelers shown in Fig. 7. For liquid hydrogen, differential manometer with water and liquid paraffin was employed. (Fig. 7 (b)). For thermal insulation, vacuum of 10^<-5>mmHg was maintained inside the casing by an Sin. oil diffusion pump and a rotary pump of speed 1200l/min. For purification of hydrogen the feeded gas was first passed through the purification curcuit surrounding the regenerative exchanger and impurities solidified were separated by a small cyclon. And during operation, it was purified by passing through a charcoal purifier cooled by liquid nitrogen under reduced pressure of 300〜400mmHg. For production of liquid hydrogen, the pressure of liquid nitrogen bottle was reduced to 100〜150mmHg., that is, the temperature of 64〜66°K. At the early stage of operation, hydrogen gas, compressed to 150atm was expanded to 0.5atm and by-passed by the by-pass valve in order not to return through the regenerative exchanger till the temperature at the expansion valve reached below 90°K. When this temperature was attained, by-pass valve was shut and regeneration was started. After 20min., liquefaction of hydrogen started. One example of the performance data is shown in Fig. 8. The production rate of liquid hydrogen was about 8 liters per hour, and liquefaction efficiency was about 21%.. The consumption of liquid nitrogen in the bottle was about 1.2 liter per 1 liter of liquid hydrogen produced.
宇宙航空研究開発機構の論文
1958-03-13

東大理工学研究所の水素液化機

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