DETERMINATION OF TIME RELAXATION COEFFICIENT IN LEE MODEL FOR LIQUID HELIUM RELEASE AND DISPERSION

This study presents the development and comparison of a CFD model to predict dispersion and spills formation of liquid helium (LHe) at cryogenic temperatures. The work is motivated by safety design considerations behind magnetocaloric hydrogen liquefaction system, where LHe is a primary coolant. A contemporary CFD model is essential for assessment of LHe hazards in confined spaces. The CFD
setup replicates a controlled experiment involving a 1 L helium spill in a .0×3.7×2.7 m enclosure, including humidity variation and sensor-based concentration measurements. The model employs a Volume of Fluid (VOF) approach with the Lee phase-change model and accounts for multiphase species transport. Impact of Lee’s model time relaxation parameter on simulation results was studied, the value r=0.1 provided the best agreement with experimental data for lower Dewar vessel elevations during spillage. This value is consistent with the range commonly applied in cryogenic CFD studies, particularly for LH2 simulations, and aligns with previous findings where in range 0.05–0.2. The model supports safety assessments of LHe releases, evaporation and distribution across a range of incident scenarios with cryogenic applications where LHe is used as a cooling agent.