Validation of hydrogen gas stratification and mixing models

Journal Article · Tue May 26 00:00:00 EDT 2015 · Annals of Nuclear Energy (Oxford)

DOI:https://doi.org/10.1016/j.anucene.2015.05.003· OSTI ID:1184714

Wu, Hsingtzu ^[1]; Zhao, Haihua ^[2]

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1. Japan Atomic Energy Agency (JAEA), Tokai (Japan)
2. Idaho National Lab. (INL), Idaho Falls, ID (United States)

Two 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 an 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 × 10⁻⁴ to 3.29 × 10⁻⁴ m³/s. In conclusion, computing time for each BMIX++ model with a normal desktop computer is less than 5 min.

• Research Organization: Idaho National Laboratory (INL), Idaho Falls, ID (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC07-05ID14517
• OSTI ID: 1184714
• Alternate ID(s): OSTI ID: 1247872
• Report Number(s): INL/JOU-14-32658; TRN: US1500199
• Journal Information: Annals of Nuclear Energy (Oxford), Vol. 85, Issue C; ISSN 0306-4549
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
97 MATHEMATICS AND COMPUTING
HELIUM
COMPUTERIZED SIMULATION
HYDROGEN
VALIDATION
COMPARATIVE EVALUATIONS
JETS
URANIUM CARBIDES
MIXING
B CODES
FLUID MECHANICS
HEAT TRANSFER
BENCHMARKS
MIXTURES
VENTS
FLOW RATE
ONE-DIMENSIONAL CALCULATIONS
ABUNDANCE
REACTOR ACCIDENTS
DESIGN
OPTIMIZATION
DISTRIBUTION
ENTRAINMENT
LEAKS
buoyant jets
enclosure mixing
hydrogen stratification
hydrogen leaks