液氮、液氢加注系统数值仿真与试验研究

以低温液氮加注系统为研究对象,通过FLUENT仿真与试验研究,结果表明：数值仿真与试验结果吻合良好,小流量预冷液氮温度升高约5 K,一定过冷度与低漏热率对单相加注具有重要作用。以低温储液瓶为研究对象,对“加注过程”进行仿真与试验,结果表明：加注初期液位高度低于临界液位,加注对整个流场扰动较大,加剧了储液瓶内部对流换热,液相区有气泡形成,部分气相二次液化,瓶内暂无温度分层;加注中后期,气液交界面趋于稳定,液相区无明显气泡,气相区无明显二次液化且温度逐渐形成分层;数值仿真与试验的液氮蒸发率分别约为1.7%和1.5%,具有较好一致性。基于液氮分析经验,对液氢“加注过程”进行仿真预测,结果表明：液氮、液氢加注过程储液瓶内部液相率与温度具有相似变化规律,液氮加注分析对液氢加注具有一定参考意义。

NUMERICAL SIMULATION AND EXPERIMENTAL STUDY OF LIQUID NITROGEN AND LIQUID HYDROGEN FILLING SYSTEM

The low-temperature liquid nitrogen filling system is taken as the research object. Through FLUENT simulation and experimental study, the results show that the numerical simulation match well with the experimental results. The temperature of the small flow pre-cooling liquid nitrogen increases by about 5 K, a certain degree of subcooling and a low heat leakage rate play an important role in single-phase filling.Taking the cryogenic liquid storage bottle as the research object, the filling process is simulated and tested. The results show that the liquid level in the initial stage of filling is lower than the critical liquid level. Internal convection heat exchange, bubbles are formed in the liquid phase, part of the gas phase is liquefied for the second time, and there is no temperature stratification in the bottle. In the middle and later stages of filling, the gas-liquid interface tends to be stable, there are no obvious bubbles in the liquid phase, and no obvious bubbles in the gas phase. The secondary liquefaction and the temperature gradually formed stratification. The liquid nitrogen evaporation rates of the numerical simulation and experiment were about 1.7% and 1.5%, respectively, with good consistency. Based on the experience of liquid nitrogen analysis, the simulation prediction of the “filling process” of liquid hydrogen is carried out. The results show that the liquid phase rate and temperature in the liquid storage bottle during liquid nitrogen and liquid hydrogen filling process have similar variation laws. Hydrogen refueling has certain reference significance.