1. Blast wave from hydrogen storage rupture in a fire
ICHS 2015
October 19-21, Yokohama, Japan
Blast wave from hydrogen storage rupture in a fire
V. Molkov, S. Kashkarov

2. Experiments Pressure measurement Debris locations (under-vehicle test)
V, L
pg, MPa
Ti, K
m, kg
ag, m/s
Stand-alone tank
72.4
34.3
300.15
1.654
1591
Under-vehicle tank 88
31.8
306.15*
1.856
1581

3. Energy of a physical explosion
Ideal and real gases
Original approach
(ideal gas)
64%
44%
New approach
(real gas)
23%
35 MPa
70 MPa
100 MPa
The real gas SHORTENS THE SEPARATION DISTANCE

4. Blast wave parameters
Physical explosion
P̅=ΔP/ps

5. Fire test – stand-alone hydrogen tank
The model omitting combustion effect
28 %
Even with the real gas, the methodology may be further improved, if combustion effects are included

6. Fire test –hydrogen tank under the vehicle
The model omitting combustion effect
“infinity”
2.6 times
52%
Experiment not predicted

7. Turbulent combustion of hydrogen
New model (1/3)
Inclusion of combustion
Shock front
Contact surface
Turbulent combustion of hydrogen

8. New model (2/3) Inclusion of combustion
The new model assumes that the chemical energy (energy of combusted H2 released into air) is dynamically added to the mechanical energy of stored hydrogen.
The new scaled non-dimensional distance, r̅P, is proposed to be used for calculation of the overpressure:

9. New model (3/3) Inclusion of combustion
The empirical coefficient for mechanical energy, a, is constant following previous studies;
The empirical coefficient for chemical energy, b, changes from 0 (at the moment of tank rupture) to 1 (maximum value of b) following the “volume” function: b ×(rsh/rb)3;
A fraction of chemical energy is feeding the shock whilst the latter is propagating;
The rest is combusted within the fireball (after the shock wave decayed far from the tank).

10. Fire test – stand-alone hydrogen tank
The new model with combustion effect
Even with the real gas, the methodology may be further improved, if combustion effects are included

11. Fire test –hydrogen tank under the vehicle
The new model with combustion effect
Experiment predicted; “plateau” is reproduced

12. Separation distances (1/2)
Harm to humans

13. Separation distances (2/2)
Damage to buildings

14. Concluding remarks
An application of a real gas equation shortens the separation from tank explosion;
Physical explosion (without combustion) techniques cannot be applied to calculate the separation from a tank rupture in a fire as the combustion of hydrogen essentially affects the blast wave overpressure;
Blast wave decay from stand-alone and under-vehicle tank cannot be calculated in the same way (different coefficients for mechanical and chemical energy applied);
On-board hydrogen storage system should be designed in a way that the released energy is absorbed in case when the tank ruptures;
The engineering solutions should exclude the fire subjected to large stand-alone tanks at refuelling stations (e.g. by means of specific design).

15. Thank you for your attention.

16. (free download eBook, bookboon.com,
Acknowledgements
The authors are grateful to:
Fuel Cell and Hydrogen Joint Undertaking for funding through HyResponse project (
Engineering and Physical Sciences Research Council (UK) for funding through Hydrogen and Fuel Cells Supergen Hub project (
Dr Simon Jallais for the valuable comments.
Learn more!
Fundamentals of Hydrogen Safety Engineering
(free download eBook, bookboon.com,
October 2012)