液体水素タンクの効率改善に関する研究(Study points way to more efficient liquid hydrogen tanks)

2025-08-21 ワシントン州立大学 (WSU)

ワシントン州立大学(WSU)の研究者らは、液体水素の貯蔵効率を高めるための数学モデルと運用上の提案を新たに開発しました。液体水素は非常に低温(約20K)で保存する必要があり、輸送時には蒸発による燃料損失が課題となっています。研究により、特に移送中の冷却配置で約13%の水素が蒸発によって失われていると特定されました。一方、リリーフバルブ(安全弁)の作動圧力を調整するという単純な操作変更により、水素損失を約26%削減できることが明らかになりました。この成果はモデルと現場管理の改善が液体水素の利用性と経済性を大幅に高める可能性を示すものであり、燃料インフラの効率と実用性向上に貢献する実用的なアプローチです。

<関連情報>

液体水素タンクの操作が蒸発損失に与える影響のモデル化 Modeling the effects of liquid hydrogen tank operations on boil-off losses

K.R. Appel, K.I. Matveev, J.W. Leachman
Cryogenics  Available online: 5 August 2025
DOI:https://doi.org/10.1016/j.cryogenics.2025.104161

Highlights:

  • Liquid hydrogen storage tank operations contribute to boil-off losses.
  • A numerical model is developed to account for operational effects on losses.
  • The model is validated with NASA test stand and in-service tank pressure data.
  • Parametric analyses investigate methods for reducing operational boil-off losses.

Abstract

Popular choices for storing bulk hydrogen include 100 bar gas, 200 bar gas (GH2), and liquid (LH2) kept in cryogenic tanks. LH2 achieves a greater volumetric density than GH2 albeit with ambient heat load causing hydrogen boil-off and self-pressurization. Although many models are available in the literature for self-pressurization, few if any studies have applied these models to real-world tank operational scenarios, such as filling or venting, to determine optimal tank settings. To address this need, a non-thermal equilibrium reduced-order model is developed and validated using experimental data from NASA’s Integrated Refrigeration and Storage System (IRAS) and an in-service LH2 storage tank in industry. Five parametric studies are conducted to explore the effects of liquid extraction with initial tank fill level, tank filling conditions, vapor return percentage, temperature of vapor return, and saturated liquid return on boil-off losses. One parametric study estimates a boil-off reduction of 15 % by extracting hydrogen from the tank as a liquid with 30 % vapor return compared to a cyclic venting baseline study. Results indicate that operational modes for LH2 storage tanks have a significant impact on boil-off losses relative to initial tank design considerations and should be considered in the implementation of LH2 storage tanks.

0505化学装置及び設備
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