Fire Protection Strategy for Compressed Hydrogen-Powered Vehicles-Paper

Virtually all major automotive companies are currently developing hydrogen-powered vehicles.The vast majority of them employ compressed hydrogen tanks and components as a means ofstoring the fuel onboard. Compressed hydrogen vehicle fuel systems are designed in the sameway as compressed natural gas vehicles (NGV), i.e. the high pressure (up to 70 MPa) fuel isalways contained within the system under all conditions, with the exception of vehicular fire. Inthe event of a vehicle fire the fuel system is protected using a non-reclosing thermally activatedpressure relief device (PRD) which safely vents the contents. Hydrogen fuel system PRDs are presently qualified to the performance requirements specified indraft hydrogen standards such ANSI/CSA HPRD 1 and EIHP Rev. 12b. They are also qualifiedwith individual fuel tank designs in accordance with the engulfing bonfire requirements invarious published/draft tank standards such as CSA B51 Part 2, JARI S001, SAE TIR J2579,ANSI/CSA HGV 2, ISO DIS 15869.2 and EIHP Rev. 12b. Since 2000 there have been over 20documented NGV tank failures in service, 11 of which have been attributed to vehicle fires. This paper will examine whether currently proposed hydrogen performance standards andinstallation requirements offer suitable fuel system protection in the event of vehicular fires. Anumber of alternative fire protection strategies will be discussed including: i. The requirement of an engulfing and/or localized fire test for individual tanks, fuelsystems and complete vehicles;ii. The advantages/disadvantages of point source-, surface area- and/or fuse-based PRDsiii. The use of thermal insulating coatings/blankets for fire protection, resulting in the NON-venting of the fueliv. The specification of appropriate fuel system installation requirements to mitigate the