屈曲パイプ内のヘリウム(代替水素)ガス置換中の超音波による濃度変化計測

抄録

It is important to study hydrogen flow in a pipe for safety in the hydrogen society. In this study, the ultrasonic method was used to observe the helium replacement of the nitrogen-filled bent pipe, and the reliable replacement method was investigated. It is found that nitrogen in the pipe near the exit is never replaced with helium 100 % due to the difference in specific weights of nitrogen (or air) and helium. If the exit shape is changed so that the air does not flow backward into a pipe, it is found that it is possible to replace the air with helium 100 %. The ultrasonic gas concentration measurement method does not require drilling holes in the pipe for measurement and is a safe method that can measure concentrations without direct contact with the gas. Helium was used instead of hydrogen for safety reasons. Previous studies confirmed that there is almost no difference in gas replacement behavior even when helium is used as a substitute gas for hydrogen.