GASFLOW-MPI analysis on deflagration in full-scale hydrogen refueling station experiments: H_2-air premixed cloud and high-pressure H_2 jet

摘要

Safety of the hydrogen refueling station under a postulated accident (e.g. leakage) is of great importance in hydrogen energy. The predictive CFD tool GASFLOW-MPI is utilized to simulate the full-scale hydrogen refueling station deflagration experiments with premixed H-2-air cloud and high-pressure H-2 jet. The overpressures are predicted for an ignition between two dispensers in the premixed trial and a spark in the engine bay in the jet trial, which agree with the experimental data and validate the GASFLOW-MPI as well. Five turbulent burning velocity models are involved to investigate the explosion of the premixed H-2-air cloud. The Zimont correlation is recommended for the combustion simulation of engineering full-scale H-2 & nbsp; refueling station. The turbulent flame speed is predicted after an ignition resulting in 50-200 m/s, and the flame acceleration happens due to the turbulence effect by obstacles. The developments of the pressure, temperature and H-2 concentration of premixed H-2-air deflagration, indicate the pressure wave propagates with the reflections on obstacles, and the flammable H-2 cloud is enlarged by the push of combustion product.& nbsp;& nbsp;Moreover, the standard k - epsilon and DES model are adopted on the jet dispersion analysis. The local flow variables show some differences, but the global properties of average hydrogen concentration, the shape and size of the burnable cloud are similar, which indicates the hydrogen dispersion transient computed by k - epsilon turbulence model provides a reliable basis for estimating the combustion process. The evolutions of the jet resulting burnable H-2-air mixture in the domain in terms of H-2 velocity field, concentration and mass are evaluated. The velocity field in jet trial explains that the momentum dominates hydrogen dispersion and result in a corresponding hydrogen concentration, however a large zone with high turbulence forms after combustion. The analysis of H-2 dispersed in the engine bay shows the growth and decay of the hydrogen concentration above some specified value of interest (4 and 10 vol% H-2). Most dispersed H-2 cloud is burnable, and half of the mass distributed in the cloud above 10 vol% may accelerate the flame to sonic. The comparison of the overpressure in k - epsilon and DES turbulence models with real and ideal gas release sources, shows in general no significant difference. The hydrogen release jet with higher turbulence generates the hydrogen cloud that can result in a large overpressure. (C)& nbsp;2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.& nbsp;& nbsp;