CFD SIMULATION OF PRESSURE REDUCTION INSIDE LARGE-SCALE LIQUEFIED HYDROGEN TANK
CFD SIMULATION OF PRESSURE REDUCTION INSIDE LARGE-SCALE LIQUEFIED HYDROGEN TANK
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发表时间：
2021
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通讯作者：
Tani
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作者：
Tani
构建国际氢供应链需要大型液化氢（LH 2）运输船。在使用LH 2运输船运输LH 2期间，由于外部热量进入，罐通过LH 2蒸发加压。在接收终端卸载液氢之前，降低储罐压力对于储罐安全运行至关重要。但压力降低可能引起闪蒸，导致液化氢迅速汽化，液体泄漏。此外，据认为，压力恢复现象，这是不可取的油箱压力管理方面发生在开始减压。因此，我们的研究目的是澄清减压过程中货舱内的现象。采用基于VOF的CFD程序，采用C-CUP格式，结合混合Level Set和MARS方法，对减压现象进行了CFD分析。对30 m3液氢储罐的减压实验进行了模拟，结果表明，压力恢复是由沸腾延迟引起的，在充分搅拌后，储罐压力跟随饱和压力变化。在本文中，根据温度重新评估了结果。当压力降低占主导地位时，汽液界面温度降低。一旦沸腾气泡搅动界面，其温度在压力恢复发生后达到饱和温度。此外，人们发现，在减压过程中的液体温度无法测量，因为沸腾从温度计的壁。对液氢运载船1250 m3贮箱减压过程进行了CFD分析，结果表明在一定条件下1250 m3贮箱可以发生压力恢复。这些结果为LH 2载体的发展提供了新的见解。
Building the international hydrogen supply chain requires the large-scale liquefied hydrogen(LH2) carrier. During shipping LH2 with LH2 Carrier, the tank is pressurized by LH2 evaporation due to heat ingress from outside. Before unloading LH2 at the receiving terminal, reducing the tank pressure is essential for the safe tank operation. However, pressure reduction might cause flashing, leading to rapid vaporization of liquefied hydrogen, liquid leakage. Moreover, it was considered that pressure recovery phenomenon which was not preferred in terms of tank pressure management occurred at the beginning of pressure reduction. Hence, the purpose of our research is to clarify the phenomenon inside the cargo tank during pressure reduction. The CFD analysis of the pressure reduction phenomenon was conducted with the VOF based in-house CFD code, utilizing the C-CUP scheme combined with the hybrid Level Set and MARS method. In our previous research, the pressure reduction experiments with the 30 m 3 LH2 tank were simulated, and the results showed that the pressure recovery was caused by the boiling delay, and the tank pressure followed the saturation pressure after the liquid was fully stirred. In this paper, the results were re-evaluated in terms of temperature. While pressure reduction was dominant, the temperature of vapor-liquid interface decreased. Once the boiling bubble stirred the interface, its temperature reached the saturation temperature after pressure recovery occurred. Moreover, it was found that the liquid temperature during pressure reduction could not be measured because of the boiling from the wall of the thermometer. The CFD analysis on pressure reduction of 1250 m 3 tank for the LH2 Carrier was also carried out, and showed that the pressure recovery could occur in the case of the 1250 m 3 tank in a certain condition. These results provide new insight into the development of the LH2 carrier.