Hydrogen and CNG Fuel System Safety Research

Transcription

1 Hydrogen and CNG Fuel System Safety Research Barbara C. Hennessey National Highway Traffic Safety Administration Office of Vehicle Crashworthiness Research Government/Industry Meeting January 26,

2 2012 Program update Hydrogen Research Tasks: Task Order 1, Compressed Hydrogen System Fueling Options for Crash Testing generating data on effects of fuel container pressure and orientation on performance in crashes (Completed 2011) Task Order 2, Cumulative Fuel System Life Cycle and Durability Testing of Hydrogen Gas Storage Systems generating data on potential life-cycle safety issues of these fuel systems (Completed 2011) Task Order 3, Post-Crash Hydrogen Leakage Limits generating data on effects of hydrogen leaks and ignition in and around vehicles (Completed 2011) 2

3 2012 Program Update New CNG Research Tasks: In 2009 ODI was involved in several failure (rupture) investigations of certified aged CNG cylinders in real world service ODI worked with DOE/NREL sponsored Clean Vehicle Education Foundation on these investigations DOE/NHTSA management met to discuss sharing lessons learned in H2 and CNG research, demonstration and deployment programs DOE/NHTSA Compressed Natural Gas and Hydrogen Fuels: Lessons Learned for the Safe Deployment of Vehicles Workshop, Washington DC, December 2009 Invited experts from US, China, Brazil DOE International Hydrogen Fuel and Pressure Vessel Forum, Beijing PR, September 2010 Invited experts from China, Europe, US 3

4 2012 Program Update New CNG Research Tasks: Lessons Learned Can Improve Safety of both CNG and Hydrogen Obtain several samples of aged cylinders from the fleets that had failures and conduct failure analysis to determine root cause IAA with NASA/ White Sands Test Facility Experts in composite overwrapped pressure vessel inspection techniques Develop public awareness campaign and cylinder tracking program to insure they are inspected as required and removed and destroyed at end of life IAA with National Renewable Energy Laboratory (DOE Clean Cities Program) to the Clean Vehicle Education Foundation Experts in CNG accident investigation 4

5 Task 1, Compressed Hydrogen System Fueling Options for Crash Testing Three subtasks - Container vulnerability to impact - Helium as a substitute test gas to monitor leakage post-crash - Vehicle crash tests CNG Civics retrofitted w/hydrogen cylinders 5

6 Results of Container Crush Tests Service Pressure Test Condition Type 3 (Dynetek) Type 4 (Lincoln) Test Test End Result Test # Result Pressure # Orientation 350 Horizontal 10% Plug Horizontal 100% Plug Horizontal 10% Plug Vertical 10% Plug 7 No leak or rupture, no visible damage No leak or rupture, no visible damage No leak or rupture, no visible damage Leakage (34.7 to 0.1 bar in 4.25 s) 350 Vertical 100% Plug 8 Rupture Vertical 10% Plug 9 Leakage (73.1 to 0.2 bar in 3.5 s) 700 Vertical 100% Plug Vertical 10% Valve 13 Leakage (36.3 to 0.2 bar in 1.95 s) 350 Vertical 100% Valve 14 Rupture Vertical 10% Valve 15 Leakage (72.4 to 0 bar in 1.8 s) No leak or rupture, fiber breakage on top surface No leak or rupture, fiber breakage on top and bottom surface No leak or rupture, minor fiber breakage on top surface Leakage (35.6 to 0.2 bar in 2.55 s) Rupture, plastic welds failed Leakage, via sheared fitting Leakage, via deformed end plug (700 bar to 0 bar in 14 hours or ~50,000 s) Leakage (35.2 to 0.1 bar in 2 s) Small rupture or big leak 6

7 Leak Characterization using Hydrogen vs. Helium as Test Fill Gas FMVSS 301 and 303 utilize Stoddard and nitrogen as surrogates for gasoline and CNG in fuel system integrity crash tests SAE 2578 provides alternate formulas for testing with high pressure hydrogen and helium, and low pressure hydrogen to monitor post-crash leakage Test matrix included 48 leak tests of hydrogen and helium at high and low pressure (100% and 10% fill) Results: Pressure drop formula tracked mass flow at high pressures Compressibility of gases at low pressure and very slow leaks need adjustment at a range of temps and pressure 7

8 High-Level Results of Vehicle Crashes with Hydrogen Onboard Crash Initial Pressure Peak Acceleration of the Vehicle CG What Happened Pressure Front 48 kph 30 mph 35 bar 500 psi 10% 28 G (x axis) The container rocked in its mount. Held Rear 80 kph 50 mph 35 bar 500 psi 10% 22 G (x axis) Mounting anchors ripped, and the container came partly into the rear seat. Held Side 53 kph 33 mph 350 bar 5000 psi 100% 17 G (y axis) The barrier did not penetrate to the container. (The post-crash vent system malfunctioned.) 8

9 Production Proof Pressure Leak/Permeation > 30 hrs Leak/Permeation Leak/Permeation > 30 hrs Pressure Task 2, Cumulative Fuel System Life Cycle Testing Test matrix evaluates test temperatures, cycling count, parking performance Temp extremes of -40, -25, +55, +65 Duration of static hold for permeation measurement of 30, 100, 500 hours Cycle count of 500, 1000, 1833 cycles Burst Expected-Service Performance Verification test <20% Burst until the system is saturated with hydrogen (steady state permeation 180%NWP or 30 hours whichever is greater) 30 sec 125%NWP Task 2c Task 2b 150% NWP a b,c * ** 500hr 500hr C o C time Task 2a %cy -40C -40 o C a 25 25%cy -40C +50 o C 25%cy 25cy +50C +50 o C b,c 25cy 25%cy +50C -40 o C 125%NWP 200cy ambient 15-25C 200cy 125%NWP 15-25C ambient 125%NWP 125%NWP a System -40 o C 5cy +20 o C fuel; 5cy <-35 o C fuel b System +50 o C 5cy <-35 o C fuel c Service defuel rate >50cy 9

10 Task 3, Post-crash Fuel Leakage and Fire Safety Experiments for Hydrogen Vehicles Assess the fire safety of proposed leakage limit of 118 NL/min, which is based on the thermal energy equivalent to gasoline in FMVSS 301 Task A: Conduct leak rate vs. H2 accumulation tests on intact automobiles Task B: Conduct ignition and combustion tests on simulated automobile compartments (engine, passenger, trunk) Task B: Conduct full-scale leak, ignition, and fire test on intact and crashed automobiles 10

11 Hydrogen Sensor Setup Sensors placed at 10%, 50% and 90% height of each compartment U.S. DOT National Highway Traffic Safety Administration 11

12 A. Intact Vehicle 118 lpm Trunk Leak 12

13 Task C, Leak and Ignition Tests on Vehicles Intact and crashed vehicles obtained from compliance and NCAP programs for hydrogen accumulation and ignition tests 13

14 Ignition Test Matrix Vehicle Task C Vehicle Ignition Tests Leak Rate (lpm) Leak Duration (min) Test # Ignition? Secondary Fire? Front Impact Intact Rear Impact Yes Yes No No Yes Yes No No No No Yes No Yes No Side Impact Yes Yes 14

15 Summary and Conclusions 88 accumulation, ignition, and sensor response time tests were conducted in intact, simulated and crashed vehicles. Leaks up to double the proposed post-crash limit, when directed outside and under the vehicle did not reach flammable concentrations Leaks as low as 6 lpm could result in flammable concentrations if directed inside the vehicle Hydrogen concentration within the trunk or occupant compartment should not exceed the LFL of 4% 15

16 CNG and Hydrogen Vehicle Stats Population and failures 11,000,000 CNG vehicles worldwide Top ten countries using CNG vehicles are Pakistan, Argentina, Iran, Brazil, India, Italy, China, Columbia, Ukraine, Bangladesh 125K CNG vehicles in the US (ranks 14 th ) Hydrogen vehicles worldwide Cylinder failures Powertech and CVEF maintain databases of failures, with about 100 serious failures recorded for CNG. No serious failures have been reported for hydrogen vehicles. 16

17 2012 Program CNG Research Tasks: IAA NASA WSTF, Testing and Failure Analysis of COPVs Destructive and non-destructive evaluations of new and old Type II, III, and IV cylinders IAA NREL, NGV Cylinder Safety, Education, Tracking, and Failure Research Work with NREL and CVEF to track aged cylinders, remove from service, provide decommissioning guidelines. 17

18 Failure Investigation Agreement with NASA/WSTF Test articles come from two different CNG fleets that experienced rupture subsequent to refueling: Philadelphia Gas Works 1998 Ford van Type-2 Lucas Aerospace Pasadena CA Dydee Diaper step van - Type-4 Brunswick (Lincoln Composites) Cylinders were certified to FMVSS 304 and to the industry standard ANSI/NGV2, and in both cases well into their 15 year certification These failures are significant in that they indicate that compliance to the standards did not ensure safety in use 18

19 NDE Techniques Acoustic Impedance Testing Induce varying acoustic waves in composite structure Differentiates acoustic differences between damaged and undamaged regions X-ray Radiography Identifies defects in metallic components Infrared Thermography Measure hot spots and correlate with other NDE techniques Eddy Current Magnetic fields for crack detection Ultra-sonic Time/Amplitude Scan Laser Shearography Optical method to detect flaws Flash Thermography Highlights details from numerical processing of hundreds of images 19

20 Flash Thermography Laser Shearography IR Thermography Acoustic Emission 20

21 TYPE OF DAMAGE Indentation Chip (Fiber Damage) Crack (Fiber Damage) Scratch (Fiber Damage) Scuff (Fiber Damage) Void (Internal) Delamination Liner Disbond Liner Defects General Diagnostics Local Diagnostics NDE Application Matrix The use of multiple NDE methods improve detection ability Visual Acoustic Impedance TYPE OF NDE INSPECTION Radiograph Ultrasound Heat soak Thermography Eddy Current Flash Thermography Shearography Recommended method Limited Usefulness 21

22 Destructive Testing of Cylinders Post-NDE Review Team review and recommendation for destructive evaluation, For example, Burst Test Pneumatic burst testing shall be performed on selected COPVs that have had characterizing NDE performed to simulate failure of interest. Report of data findings, observations, test procedures, recommendations. 22

23 IAA with NREL/Clean Vehicle Education Foundation Task I End User and Industry Awareness Campaign Develop new CNG Cylinder Safety Educational tools for decommissioning and disposal of cylinders Develop General Guidelines for CNG cylinder safety to be distributed by SVMs, conversion shops and fueling station Operators to the NGV end users Task 2 - CNG Cylinder Tracking 23

24 Public awareness campaigns, installation procedures and cylinder tracking to avoid situations like this Dydee step van Type-4 refueling rupture 24

25 and this Improper decommissioning of cylinders Cylinder in scrap yard is punctured by heavy equipment during separation for salvage. Travels over 600 ft and crashes through house solar panels. 25

26 Summary of Hydrogen and CNG Research Results H2 program generated a lot of useful data on Composite cylinder durability, through impact and simulated life cycle testing of new cylinders Hydrogen leak and ignition behavior in vehicle interior compartments CNG program Developing state-of-the-art diagnostic tools to monitor cylinder health and understanding of failure modes, and design and manufacturing weaknesses Providing education, best practices, and accountability in-use to prevent service failures. 26

27 Thank you! Questions? 27