Discharge Modeling of Large Scale LH2 Experiments with an Engineering Tool

Accurate estimation of mass flow rate and release conditions is important for the design of dispersion and combustion experiments, for the subsequent validation of CFD codes/models, for consequence assessment analysis within related risk assessment studies and for associated Regulation Codes and Standards development. This work focuses on the modelling of the discharge phase of the recent large scale LH2 release and dispersion experiments performed by HSE within the framework of PRESLHY project. The experimental conditions covered sub-cooled liquid stagnation conditions at two pressures (2 and 6 bara) and 3 release nozzle diameters (1, ½ and ¼ inches). The simulations were performed using a 1d engineering tool, which accounts for discharge line effects due to friction, extra resistance due to fittings and area change. The engineering tool uses the Possible Impossible Flow (PIF) algorithm for choked flow calculations and the Helmholtz Free Energy (HFE) EoS formulation. Three different phase distribution models were applied. The predictions are compared against measured and derived data from the experiments and recommendations are given both regarding engineering tool applicability and future experimental design.