Study on the Harm Effect of Liquid Hydrogen Release by Consequence Modeling

1. Presentation for ICHS 2011 Study on the Harm Effect of Liquid Hydrogen Release by Consequence Modeling Presented by: Dr. LI. Zhiyong Instructed by: Prof. MA. Jianxin Dr. PAN. Xiangmin September 14th, 2011 Institute for Hydrogen Energy Technologies

2. Introduction of IHET in Tongji University • IHET (Institute for Hydrogen Energy Technologies)has been focused on • hydrogen infrastructure R&D in China for more than 10 years. • Engineering practice on hydrogen technologies • Four hydrogen refueling stations (HRS); Several mobile HRS; A demo coking gas purification facility • Technical experience in building codes and standards • Technical Code for Hydrogen Fuelling Station (GB50516-2010); • Technical Specification of Hydrogen Refueling Stations for Fuel Cell Vehicles (DGJ08-2055-2009) • Numerical research experience on hydrogen releases • The potential hazards of accidental gaseous hydrogen release; • The harm effect of different consequences such as jet fire, flash fire, physical explosion and vapor cloud explosion.

3. First HRS developed by IHET 2006, Shanghai Anting HRS, serving for FCVs test for 2008 Olympic Games

4. Hydrogen supply network developed by IHET • 2010, Expo station, serving for FCVs for 2010 Expo Anting HRS By-product H2 Purification Plant EXPO HRS Mobile HRS 100 6 90 FC Sight-seeing Cars FC Buses FC Cars

5. Hydrogen filling infrastructure built by IHET recently 2010, Guangzhou HRS, serving for the 2010 Asian Games 2011, Shengzhen HRS, serving for the 2011 World University Games

6. Contents • 1. Introduction • 1.1 Background and objective of this study • 1.2 Potential hazard of liquid hydrogen storage • 2. Modeling • 2.1. Possible consequences of liquid hydrogen release • 2.2 Harm criteria • 2.3 Model and assumptions • 3. Results and discussions • 3.1 Harm effect distance of each consequence • 3.2 Comparison with compressed hydrogen vessel • 4. Summary

7. 1. Introduction • 1.1 Background and objective of this study • Liquid hydrogen can be stored and transported in much larger quantities than compressed hydrogen and may be considered as an alternative storage for hydrogen vehicles. • This paper studies the accidental release of hydrogen from cryogenic liquid storage tank and calculates the subsequent consequences such as hydrogen cold cloud, fire ball, jet fire, flash fire, and vapor cloud explosion. • The purpose is to evaluate the harm distance of the cold effect, thermal effects and overpressure effects from above hydrogen consequences.

8. 1. Introduction • 1.2 Potential hazard of liquid hydrogen storage • The principle hazard associated with cryogenic storage is the accidental released hydrogen related to its low temperature and flammable potential. • For low temperature, the reduction in temperature by the released hydrogen may cause cryogenic burns to people. • For flammable effect, the primary hazard is related to fire and explosions. In a fire event, the radiant heat fluxes or direct contact with hydrogen flames may cause burn to people. In vapor cloud explosion event, the blast wave overpressures are harmful to people.

9. Without ignition Cold cloud Instantaneous release Direct ignition Fireball Flash fire With ignition Liquid hydrogen Delayed ignition Vapor cloud explosion Without ignition Cold cloud Direct ignition Continuous release Jet fire Flash fire With ignition Delayed ignition Vapor cloud explosion Figure 1 Event tree of liquid hydrogen release 2. Modeling 2.1 Possible consequences of liquid hydrogen release

10. 2. Modeling 2.2 Harm criteria Table 1 Harm criteria used in modeling [1] IGC Doc 75/07/E/rev. Determination of Safety Distances. European Industrial Gases Association, 2007 [2]CPR 16E (Green Book). A Model for the determination of possible damage. TNO,1992

11. 2. Modeling • 2.3 Model and assumptions • The thermal effects including both direct flame contact and heat radiation from immediate ignition consequences are calculated with fireball model by Martinsen, et al [3] and jet fire model by Cook, et al [4], respectively. • The explosion overpressure of a vapor cloud explosion is calculated with a Baker-Strehlow method [5]. [3] Martinsen, et al.，An improved model for the prediction of radiant heat from fireballs. International conference and workshop on modelling the consequences of accidental release of hazardous materials, San Francisco California, 1999 [4] Cook J, et al. A comprehensive program for calculation of flame radiation levels. Journal of Loss Prevention in Process Industries, 1990 [5] Baker, Q. A. et al, Recent Developments in the Baker-Strehlow VCE Analysis Methodology, the 31st Loss Prevention Symposium, 1997

12. 2. Modeling • 2.3 Model and assumptions Table 2 Modeling assumptions and parameters

13. 45 0.07bar 40 4% concentration 35 30 25 -40℃ 20 9.5kW/m2 15 10 520 (kW/m2)3/4s Flame contact 5 Not reached 0 Cold cloud Fire ball Flash fire Vapor cloud explosion 3. Results and discussions 3.1 Harm effect distance of each consequence Vapor cloud explosion>flash fire>cold cloud>fireball Harm effect from the heat radiation of the fireball may be neglected Harm effect distances (m) Figure 2 harm effect distances of catastrophic rupture of liquid hydrogen tank

14. Harm effect distances (m) 12 0.07bar 10 8 9.5kW/m2 520 (kW/m2)3/4s 6 Flame contact 4% concentration 4 -40℃ 2 0 Cold cloud Flash fire Vapor cloud explosion Jet fire 3. Results and discussions 3.1 Harm effect distance of each consequence Vapor cloud explosion>jet fire>flash fire>cold cloud Thermal dose of Jet fire> fireball for the reason of duration Catastrophic rupture is the dominate event rather than leak scenarios Figure 3 harm effect distances of 10mm leak from liquid hydrogen tank

15. Harm effect distances (m) 12 Cold effect Flame contact of jet fire Thermal radiation intensity from jet fire 10 Thermal dose from jet fire Flame contact of flash fire 8 Overpressure from vapor cloud explosion 6 4 2 0 1 4 5 6 7 9 10 11 2 3 8 Release diameter (mm) 3. Results and discussions 3.1 Harm effect distance of each consequence Harm effect distances increases with the growth of leak diameter Harm sequence do not change with leak diameters Figure 4 harm effect distances for leak from liquid hydrogen tank with different release hole size

16. Harm effect distances (m) 45 40 Liquid hydrogen 35 70MPa hydrogen storage 30 25 20 15 10 5 0 Cold cloud Physical explosion Fire ball Flash fire Vapor cloud explosion 3. Results and discussions 3.2 Comparison with 70MPa storage With ignition, liquid hydrogen storage may be more dangerous Without ignition, liquid hydrogen storage may be safer In total, liquid hydrogen storage may be more dangerous than 70MPa storage in case of catastrophic rupture Figure 5 harm effect distances of catastrophic rupture under different storages

17. Harm effect distances (m) 60 Liquid hydrogen 50 70MPa storage 40 30 20 10 0 Cold cloud Jet fire Flash fire Vapor cloud explosion 3. Results and discussions 3.2 Comparison with 70MPa storage With ignition, liquid hydrogen storage may be safer Without ignition, liquid hydrogen storage may be a little more dangerous In total, liquid hydrogen storage may be safer than 70MPa storage in case of leak scenario Figure 6 harm effect distances of 10mm leak under different storages

18. 4. Summary • For instantaneous releases of liquid hydrogen, the sequence of harm effect distances is that vapor cloud explosion>flash fire>cold cloud> fireball. • For continuous releases of liquid hydrogen, the sequence of harm effect distances is that vapor cloud explosion>jet fire>flash fire>cold cloud. • The liquid hydrogen storage may be safer than 70MPa gaseous storage in case of leak scenario but may be more dangerous than 70MPa storage in case of catastrophic rupture. It is difficult to tell which storage is safer from a consequence perspective. Further investigation need to be made from a standpoint of risk, which will combine both consequences and the likelihood of scenarios.

19. Thanks for Your Kind Attention • Welcome Your Comments!