Ultrafast Liquid Hydrogen Chilldown by Coexistence of Nucleate and Film Boiling

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K04477
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 24010:Aerospace engineering-related
• Research Institution: Shizuoka University
• Principal Investigator: Fukiba Katsuyoshi 静岡大学, 工学部, 准教授 (50435814)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 液体水素 / 予冷 / 沸騰伝熱 / 極低温燃料

Outline of Final Research Achievements

A method was proposed for accelerating the chilldown process in pipes with liquid nitrogen flow. Grooves were machined in the axial direction on the inner surface of the pipe. Subsequently, the grooves were filled with silicone sealant. We have attempted to reduce the chilldown time by simultaneously generating nucleate boiling and film boiling. In a pool boiling experiment using liquid nitrogen, the chilldown time was reduced to 1/3.9 at maximum. In the piping flow experiment using liquid nitrogen, the chilldown time was also reduced to 1/3.6 by applying the proposed surface texture. On the other hand, in the piping flow experiment using liquid hydrogen, the cooling time did not decrease.

Free Research Field

伝熱工学、航空宇宙工学

Academic Significance and Societal Importance of the Research Achievements

ロケットなどで極低温流体を用いる際、常温の配管を極低温にまで冷やす「予冷」と呼ばれる予備冷却作業が必要となり、長い時間を要する。本研究ではこの予冷時間を短縮する表面加工を開発した。液体窒素の場合は平板を用いた場合、配管を用いた場合ともに予冷時間を大幅に低減させることに成功した。液体水素を用いた場合では予冷時間を短縮することができなかった。しかし本研究によりこれまで明らかにされていない液体水素の特異な冷却挙動が観測された。