HySafe SBEP-V20 - Numerical Predictions of Release Experiments Inside a Residential Garage with Passive Ventilation

This work presents the results of the Standard Benchmark Exercise Problem (SBEP) V20 of WP6 of HySAFE Network of Excellence (NoE), co-funded by E.C., in the framework of evaluating the quality and suitability of codes, models and user practices by comparative assessments of code results. The benchmark problem SBEP-V20 is based on release scenarios that were experimentally investigated in the past using helium as a substitute to hydrogen. The aim of the investigations was to determine the ventilation requirements for parking hydrogen fuelled vehicles in residential garages. Helium is released under the vehicle for 2 hours with 7.200 L/hr flow rate. The leak rate corresponds to a 20%2drop of the peak power of a 50kW fuel cell vehicle. Three double vent garage door geometries are considered. In each case the vents are located at the top and bottom of the garage door. The vents vary only in height. In the first case, the height of the vents is 2.5 inches, in the second 9.5 inches and in the third 19.5 inches. Five HySAFE partners participated in this benchmark. The following CFD packages with the respective models have been applied to simulate the experiments: ADREA-HF using k-e model by partner NCSRD, FLACS using k-e model by partner DNV, FLUENT using k-e model by partners UPM and UU and CFX using laminar and the low-Re number SST model by partner JRC. This study compares the results predicted by the partners to the experimental measurements at four sensor locations inside the garage with an attempt to assess and validate the performance of the different codes and models. Furthermore, the effect of passive ventilation on the formation of flammable cloud is investigated.