Experimental and numerical investigations of fluid flow and heat transfer in a cryogenic tank at loss of vacuum

The transient process of thermal stratification in liquid nitrogen (LN₂) induced by lose of vacuum in a multi-layer insulated cryogenic tank is investigated both experimentally and numerically. In the experiments, distribution and evolution of the liquid temperature is obtained using thermocouples. Then, two-dimensional numerical computations are performed, using the two-fluid model together with nucleate boiling model as the closure correlations. Comparison of the numerical results against the experimental data illustrates that the process of thermal stratification forming and weakening, as well as the liquid temperature field are satisfactorily simulated. The computed results of liquid flow field contribute to the understanding of this transient process. It is also demonstrated that the two-phase flow in the tank plays an important role on thermal stratification.