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

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

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

Blast wave parameters Physical explosion P̅=ΔP/ps

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

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

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

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:

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).

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

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

Separation distances (1/2) Harm to humans

Separation distances (2/2) Damage to buildings

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).

Thank you for your attention.

(free download eBook, bookboon.com, Acknowledgements The authors are grateful to: Fuel Cell and Hydrogen Joint Undertaking for funding through HyResponse project (www.hyresponse.eu); Engineering and Physical Sciences Research Council (UK) for funding through Hydrogen and Fuel Cells Supergen Hub project (http://h2fcsupergen.com/); Dr Simon Jallais for the valuable comments. Learn more! Fundamentals of Hydrogen Safety Engineering (free download eBook, bookboon.com, October 2012)