Validation of hydrogen gas stratification and mixing models

Abstract

a b s t r a c tTwo validation benchmarks confirm that the BMIX++ code is capable of simulating unintended hydrogen release scenarios efficiently. The BMIX++ (UC Berkeley mechanistic MIXing code in C++) code has been developed to accurately and efficiently predict the fluid mixture distribution and heat transfer in large stratified enclosures for accident analyses and design optimizations. The BMIX++ code uses a scaling based one-dimensional method to achieve large reduction in computational effort compared to a 3-D computational fluid dynamics (CFD) simulation. Two BMIX++ benchmark models have been developed. One is for a single buoyant jet in an open space and another is for a large sealed enclosure with both a jet source and a vent near the floor. Both of them have been validated by comparisons with experimental data. Excellent agreements are observed. The entrainment coefficients of 0.09 and 0.08 are found to fit the experimental data for hydrogen leaks with the Froude number of 99 and 268 best, respectively. In addition, the BIX++ simulation results of the average helium concentration for a enclosure with a vent and a single jet agree with the experimental data within a margin of about 10% for jet flow rates ranging from 1.21 Â 10 À4 to 3.29 Â 10 À4 m 3 /s. Computing time for each BMIX++ model with a normal desktop computer is less than 5 min.Published by Elsevier Ltd.

Personnel safety with pressurized gas systems

“…This jet model is a generic free jet model and is capable of simulating any non‐condensable gas with or without buoyancy. The Schatzmann's jet model and the BMIX++ code have been validated with hot air jet experiments and hydrogen jet experiments . The energy density only includes kinetic energy flux and ignores the enthalpy flux ( ).…”

Analytical investigation of hydrogen distribution with steam condensation in confined vessel

“…El-Amin et al 20 proposed an integral model to describe pure hydrogen buoyant jet resulting from a small-scale leakage into air, but the effects of steam in ambient and condensation were not considered. Wu et al 21 developed 1D models for hydrogen behaviors mixing with air and applied them to safety analysis code BMIX++. Tong et al 22 developed a semi-empirical model to predict hydrogen distribution in pure air, still with the condensation not considered in the model.…”