環状流路における垂直上昇気液二相流の流動特性

摘要

地熱あるいは高温廃熱を回収する方法の一つと して，二重管熱交換器が考えられる.これは內管と 外管の間（環状流路）に水を流し，水が熱交換器外 部の熱を吸収して外部の熱を回収するものである. この時，環状流路内で水蒸気と水の二相流が発生す ることから，二重管熱交換器の設計には，環状流路 内気液二相流の流動特性を理解する必要がある.%Flow characteristics of gas-liquid two-phase flows in annular channel was conducted to obtain detail data for heat exchanger design. The test section was a double-tube, and the two-phase flows flowed upward in the gap between them. Inner diameter of the outer tube was 25mm and outer diameters of the inner tubes were 20mm and 15.4mm. Flow pattern was investigated in both flow channels, and it was compared with the flow pattern in circular tubes. The effects of the annular channel on the flow pattern were remarkable in bubbly and annular flows. Liquid lump velocity was also measured, and the velocity of liquid slugs in the annular channel was found to be higher than that in the circular channel. The velocity of a single gas-slug was measured and it was clarified that voia fraction of gas slug in the annular channel was smaller than that in the circular channel, so that it caused the velocity difference between those channels.