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INTERNATIONAL CONFERENCE ON HYDROGEN SAFETY September, 11-13 2017 - Hamburg (Germany). ID 104. The residual strength of automotive hydrogen cylinders after exposure to flame s. Yohsuke Tamura, Koji Yamazaki, Kiyotaka Maeda and Kenji Sato ( JARI , Toho Univ.). Contents.
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INTERNATIONAL CONFERENCE ON HYDROGEN SAFETY September, 11-13 2017 - Hamburg (Germany) ID 104 The residual strength of automotive hydrogen cylinders after exposure to flames Yohsuke Tamura, Koji Yamazaki, Kiyotaka Maedaand Kenji Sato (JARI,Toho Univ.)
Contents • Back groundand purpose • Structure of cylinder • Safety requirement for the handing of cylinder exposed to fire • Test method and test condition • Results • Temperature and Internal pressureduring fire • Appearance of cylinders after exposure to flames • The residual strength of cylinders after exposure to flames • Consideration • Summary
Structure and type of automotive CFRP cylinders CFRP cylinder TPRD Type Ⅲ: aluminum alloy Type Ⅳ:plastic Liner CFRP Carbon fiber Matrix resin
About TPRD(Thermal Pressure Relief Device) TPRD Gas CFRPcylinder To prevent the rupture of the cylinder, TPRD attached on the CFRP composite cylinder, was activated by the heat of fire.
Safety requirement for the handing of cylinder exposed to fire TPRD CFRPcylinder When the fire is extinguished before TPRD is activated, the high-pressure gas is left inside the cylinder damaged by fire. For the safe handling of such a cylinder, it is necessary that despite damage by fire the cylinder retain sufficient strength for withstanding the internal gas pressure.
In this study Using the cylinder without the TPRD in order to assuming the worst condition that the TPRD did not activate, residual strengths of the cylinders after burning that overheated to just before rupture or leakage were examined.
Test method Pressure Pressure Temp. Temp. Rupture conditions at a constant buring fire (temperature, pressure, time, etc.) Water Natural cooling Hydraulic burst test Sample cylinders cut off the fire source and cooling (water or natural cooling) just before rupture. These cylinders examine the bursting pressure by the hydraulic burst test.
Test condition Test cylinder: Total of five types (20~70MPaType Ⅲ, Type Ⅳ) Filling pressure : Workling pressure、 Half of the working pressure
Fire exposure conditions Burner Measure point of temp. Firepower is controlled to 600~800 °Cat 25mm from the cylinder bottom Engulfing fire、Localized fireexposured a half of the cylinder
Internal pressure during fire expose and cooling Burst pressure during fire Case: 70MPa TypeⅣ cylinder, Filling 70MPa, Engulfing fire • Supply of heat per unit time was the same condition. • These had provided the cylinders with the maximum possible exposure to flames.
Situation of flame expose test 35MPa TypeⅢNatural cooling
The appearance of a cylinderafter exposure to flames Case: 35MPa TypeⅢ cylinder, Filling 35MPa, Engulfing fire Water cooling Naturalcooling
Extinguished after the CFRP layer after extinguishment of a fire Layer of outside side were damaged by heat decomposition of matrix resin.
Heat characteristics of CFRP • Strength during heating (fire) is reduced more than the glass transition temperature Tg. • Strength after cooling (extinguished) is restored less than the heating resin loss start temperature Te. • Tg<Te Reference : A. P. Mouritz(2006), Atsushi Sumida(2008)
Image diagram of temperature and stress change in the cylinder after fire during flame exposure Restore strength of CFRP Reduction of load accompanying decrease of internal pressure The strength of the CFRP cylinder after extinguished is higher than that during fire, has the strength to withstand the filling pressure
Summary To examine the handling of the CFRP cylinder after extinguished, CFRP cylinders without pressure relief device were exposed to a fire to the verge of bursting; then after the fire was extinguished the residual burst strengths was examined. The results indicated that these cylinders had a residual strength at least twice their internal gas pressures. Therefore, we consider that the burnout of cylinder will has the strength to withstand the pressure of the filling gas.
Thank you for your attention. This study introduces one of the achievements of the “technology development project for hydrogen production, transport and storage systems” commissioned by New Energy and Industrial Technology Development Organization (NEDO) in Japan.