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

2. 2 TONGJI UNIVERSITY Institute for Hydrogen Energy Technologies 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. 3 TONGJI UNIVERSITY Institute for Hydrogen Energy Technologies First HRS developed by IHET 2006, Shanghai Anting HRS, serving for FCVs test for 2008 Olympic Games

4. 4 TONGJI UNIVERSITY Institute for Hydrogen Energy Technologies Hydrogen supply network developed by IHET 2010, Expo station, serving for FCVs for 2010 Expo 6100 EXPO HRS Mobile HRS FC Cars By-product H2 Purification Plant Anting HRS 90 FC Buses FC Sight-seeing Cars

5. 5 TONGJI UNIVERSITY Institute for Hydrogen Energy Technologies 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. 6 TONGJI UNIVERSITY Institute for Hydrogen Energy Technologies 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. 7 TONGJI UNIVERSITY Institute for Hydrogen Energy Technologies 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. 8 TONGJI UNIVERSITY Institute for Hydrogen Energy Technologies 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. 9 TONGJI UNIVERSITY Institute for Hydrogen Energy Technologies 2. Modeling Liquid hydrogen Instantaneous release Continuous release Without ignition With ignition Direct ignition Cold cloud Flash fire Vapor cloud explosion Fireball Delayed ignition Without ignition With ignition Direct ignition Cold cloud Flash fire Vapor cloud explosion Jet fire Delayed ignition Figure 1 Event tree of liquid hydrogen release 2.1 Possible consequences of liquid hydrogen release

10. 10 TONGJI UNIVERSITY Institute for Hydrogen Energy Technologies 2. Modeling 2.2 Harm criteria Table 1 Harm criteria used in modeling ConsequencesHarm effectHarm criteria to people Cold cloudCold effect -40 ℃ [1] Fire ballFlame contact ; heat radiation Fireball radius; 9.5 kW/m 2 [1] or 520 (kW/m 2 ) 3/4 s[2] Jet fireFlame contact; heat radiation Jet fame length; 9.5 kW/m 2 [1] or 520 (kW/m 2 ) 3/4 s[2] Flash fireFlame contactLower flammable limit (4%)[1] Vapor cloud explosion Overpressures0.07 bar[1] [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. 11 TONGJI UNIVERSITY Institute for Hydrogen Energy Technologies 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. 12 TONGJI UNIVERSITY Institute for Hydrogen Energy Technologies 2. Modeling Table 2 Modeling assumptions and parameters ItemCatastrophic ruptureLeak from tank Release inventory (kg)3.5 Release pressure （ bar ） 1 Release direction——Horizontal, downwind Release hole size (mm)——Vary, up to 10mm Release height (m)1 Atmospheric temperature ( ℃ ) 15 Wind velocity (m/s)5 Pasquill stabilityD (neutral) Result output height (m)1 2.3 Model and assumptions

13. 13 TONGJI UNIVERSITY Institute for Hydrogen Energy Technologies 3. Results and discussions Figure 2 harm effect distances of catastrophic rupture of liquid hydrogen tank Cold cloudFire ball Flash fire Vapor cloud explosion -40 ℃ Flame contact 9.5kW/m 2 520 (kW/m 2 ) 3/4 s Not reached 4% concentration 0.07bar 45 40 35 30 25 20 15 10 5 0 Harm effect distances (m) 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

14. 14 TONGJI UNIVERSITY Institute for Hydrogen Energy Technologies 3. Results and discussions Figure 3 harm effect distances of 10mm leak from liquid hydrogen tank Cold cloud Jet fire Flash fireVapor cloud explosion -40 ℃ Flame contact 9.5kW/m 2 520 (kW/m 2 ) 3/4 s 4% concentration 0.07bar 12 10 8 6 4 2 0 Harm effect distances (m) 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

15. 15 TONGJI UNIVERSITY Institute for Hydrogen Energy Technologies 3. Results and discussions Figure 4 harm effect distances for leak from liquid hydrogen tank with different release hole size 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 Cold effect Flame contact of jet fire Thermal radiation intensity from jet fire Thermal dose from jet fire Flame contact of flash fire Overpressure fromvapor cloud explosion 12 10 8 6 4 2 0 Harm effect distances (m) 2 41 38 56791011 Release diameter (mm)

16. 16 TONGJI UNIVERSITY Institute for Hydrogen Energy Technologies 3. Results and discussions Cold cloud Fire ball Flash fire Vapor cloud explosion Physical explosion Liquid hydrogen 70MPa hydrogen storage 45 40 35 30 25 20 15 10 5 0 Harm effect distances (m) Figure 5 harm effect distances of catastrophic rupture under different storages 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

17. 17 TONGJI UNIVERSITY Institute for Hydrogen Energy Technologies 3. Results and discussions Cold cloudJet fireFlash fire Vapor cloud explosion Liquid hydrogen 70MPa storage 60 40 50 30 20 10 0 Harm effect distances (m) Figure 6 harm effect distances of 10mm leak under different storages 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

18. 18 TONGJI UNIVERSITY Institute for Hydrogen Energy Technologies 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. 19 TONGJI UNIVERSITY Institute for Hydrogen Energy Technologies Thanks for Your Kind Attention Welcome Your Comments!