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Title: Validation of hydrogen gas stratification and mixing models

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 ×more » 10⁻⁴ m³/s. In conclusion, computing time for each BMIX++ model with a normal desktop computer is less than 5 min.« less
Authors:
 [1] ;  [2]
  1. Japan Atomic Energy Agency (JAEA), Tokai (Japan)
  2. Idaho National Lab. (INL), Idaho Falls, ID (United States)
Publication Date:
OSTI Identifier:
1184714
Report Number(s):
INL/JOU--14-32658
Journal ID: ISSN 0306-4549; TRN: US1500199
Grant/Contract Number:
AC07-05ID14517
Type:
Accepted Manuscript
Journal Name:
Annals of Nuclear Energy (Oxford)
Additional Journal Information:
Journal Name: Annals of Nuclear Energy (Oxford); Journal Volume: 85; Journal Issue: C; Journal ID: ISSN 0306-4549
Publisher:
Elsevier
Research Org:
Idaho National Laboratory (INL), Idaho Falls, ID (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
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