The accidental release of cryogenic liquids can cause several hazards to humans, assets, and the environment. Therefore, this phenomenon has drawn significant attention and has been investigated as part of quantitative risk assessment associated with the use of cryogenic liquids. However, the effects of release conditions on pool spread have not been thoroughly studied, and the mechanism of pool retraction has not been discussed. In this study, an attempt was made to address these gaps by both experimental and numerical analyses. Firstly, large-scale-outdoor release tests with a systematic measurement system were performed using liquid nitrogen to compare with large-scale release tests of liquid hydrogen. The release height and orientation were varied. It was observed that the pool shape was affected by the release orientation. However, the maximum pool size and average vaporization rate were insensitive to both the release height and orientation. The conductive heat from the ground was confirmed to be the major heat source for pool vaporization, accounting for over 90 % of the total heat transferred into the liquid pool. Subsequently, release scenarios were simulated using integral source models. Especially, several hypotheses were thoroughly discussed, implemented in the source models, and validated against experimental results to determine the most appropriate mechanism for pool retraction. The findings of this study are expected to be beneficial for the consequence estimation of cryogenic release scenarios and for the validation and improvement of source models.

中文翻译：

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大规模户外低温液体连续释放到地面上


低温液体的意外释放会对人类、资产和环境造成多种危害。因此，这种现象引起了极大的关注，并已作为与使用低温液体相关的定量风险评估的一部分进行了调查。然而，释放条件对矿池扩散的影响尚未得到深入研究，矿池回缩的机制也尚未得到讨论。在这项研究中，试图通过实验和数值分析来解决这些差距。首先，使用液氮进行系统测量系统的大规模户外释放试验，与液氢的大规模释放试验进行比较。释放高度和方向各不相同。据观察，池形状受释放方向的影响。然而，最大池大小和平均汽化速率对释放高度和方向不敏感。来自地面的传导热被证实是池蒸发的主要热源，占传递到液池的总热量的 90% 以上。随后，使用积分源模型模拟释放场景。特别是，对几个假设进行了彻底的讨论，在源模型中实施，并根据实验结果进行了验证，以确定最合适的矿池回撤机制。本研究的结果有望有利于低温释放情景的后果估计以及源模型的验证和改进。