低温液氮贮箱增压性能及热分层研究

Investigation on pressurization performance and thermal stratification in cryogenic nitrogen tank

对以液氮为工质的低温贮箱进行了增压实验,气枕压力分别从常压增压至1.93bar、1.53bar、1.21bar,由于实验过程中液位的变化影响,增压速率依次略有下降。建立了贮箱增压数值模型,对1.93bar增压过程进行了模拟分析并与实验值进行了对比。对三组增压实验过程中液氮表面的温度分层情况进行了研究,结果表明液相温度分层主要存在于液氮表面,并且温度分层情况受气枕压力的影响明显,液相主流温度区几乎不随气枕压力变化。

The pressurization experiment was carried out on the cryogenic tank which used liquid nitrogen as the working medium. When the ullage pressure rised to 1.93bar, 1.53bar and 1.21bar respectively, the pressurization rate decreased slightly as the liquid level changed gradually during the experiment. The numerical pressurization model of the cryogenic tank was build up, the process of the 1.93 pressurization was analyzed numerically and the result was compared with that of the experiment. The thermal stratification of the surface of the liquid nitrogen was investigated. It shows that the thermal stratification mainly occurs near the surface of the liquid nitrogen and is influenced distinctly by the ullage pressure, however the temperature of main stream liquid nitrogen changes hardly with the ullage pressure.