1. International Conference on Hydrogen Safety
ICHS 2011
September 12-14, 2011
San Francisco, California-USA
Validation of Computational Fluid Dynamics Models for Hydrogen Fast Filling Simulations
M. C. Galassi, E. Papanikolaou, M. Heitsch, D. Baraldi, B. Acosta Iborra, P. Moretto

2. OUTLINE Introduction GasTeF Experiments CFD Simulations Conclusions
Motivation
Fast Filling issues
Why CFD
GasTeF Experiments
CFD Simulations
Model
Results
Conclusions
Experiments
Modeling

3. INTRODUCTION Competitive with current technologies
Three main targets:
short refueling time  3 min
long driving range  MPa
high safety and reliability
Limit of 85°C
High temperature can be reached in the tank during refueling.
Limit of 85 degrees in ISO/TS 15869, 2009

4.  VALIDATION OF NUMERICAL MODELS/CODES
INTRODUCTION
WHY CFD?
CFD can provide 3D detailed and complete flow-field information over a wide range of flow configurations
Relevant information for hazards and risk assessment of hydrogen technologies (e.g. P and T loads)
Valuable contribution to design, optimization, innovative solutions
High level of reliability and accuracy of the numerical models is required in order to apply CFD to real-scale problems
 VALIDATION OF NUMERICAL MODELS/CODES

5. DATA ACQUISITION SYSTEM
GasTeF EXPERIMENTS
Gas tanks Testing Facility
EU reference laboratory on safety and performance assessment of high-pressure hydrogen (and natural gas) storage tanks
Fast filling, cyclic and permeation testing
DATA ACQUISITION SYSTEM

6. Fast filling of type 4 tanks
Experiments
Code Validation (ANSYS CFX 12.1)
Assess code accuracy of high pressure hydrogen tank fast filling
Evaluate internal and external temperature distribution
H2 Pin [MPa]
H2 Pfin [MPa]
tfilling
[s]
Tsleeve
[°C]
H2 Tini
TCs
Test H
0.02
71.7
330 16 21
Pos 2
Test H
71.8
245 18
Pos1, 2
Vol=29 l
Φ 0.28m
0.83m

7. CFD SIMULATIONS Computational model Fluid Domain Solid Domains
Hydrogen
Solid Domains
Liner (High Density Poly Amide Epoxy)
Insulation (Composite CF)
Bosses (steel)
~ 560k nodes, 900k cells
Probes at Thermo Couples position
Pos2
Pos1

8. CFD SIMULATIONS Boundary and Initial Conditions (BIC) Fluid Domain
BCs at inlet:T,p
BCs at walls: Conjugate Heat Transfer, no slip
ICs: Still at T0
Solid Domains
BC: Conjugate Heat Transfer, Heat Transfer Coefficient (with amb. air)
ICs: Tamb
Test H
Test H

9. Temperature distribution
CFD SIMULATIONS
Results
100 s
330 s
200 s
330 s
Temperature distribution

10. CFD SIMULATIONS
Results
Pos2: TC1,2,3,4,5
Test H

11. CFD SIMULATIONS
Results
Pos2: TCext1, TCext2, TCext3
Test H

12. CFD SIMULATIONS
Results
Pos1: T2,T4
Test H
Pos2: T2, T4

13. CFD SIMULATIONS Results: Maximum temperatures at Test H2 25022010
the end of the filling procedure
Test H
Pos1
Pos1
Test H

14. CONCLUSIONS (1/2)
CFD validation against experimental data for hydrogen fast filling prediction up to 72 MPa
Two different tests: similar working conditions but different filling time
The developed model proved to accurately predict internal maximum temperature for both tests (maximum error<7%),
Prediction of external maximum temperature was less accurate (maximum error~15%) and strongly dependent on material properties.

15. CONCLUSIONS (2/2) Further investigation is required on
Material properties
Heat exchange between fluid, tank walls and environment
Different turbulence models
A fully validated CFD model will
Allow reliable predictions of fast filling scenarios
Constitute a valuable complementary tool to experimental campaigns supporting
Design and optimization process
Development of innovative solutions

16. THANK YOU FOR YOUR ATTENTION !