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Rubber O-rings installed in hydrogen tanks for fuel cell electric vehicles are repeatedly exposed to high pressure hydrogen gas. Exposure to high pressure gas sometimes causes cracks as a result of blistering after decompression. The degree of blister damage is influenced by material, environmental conditions such as decompression rate, and sealing shape such as squeeze ratio. Focusing on environmental conditions out of these influential factors, in this study, a high pressure hydrogen durability tester which exposes rubber O-rings repeatedly to high pressure hydrogen gas at arbitrary test conditions was developed. Using this tester, the influence of hydrogen pressure and temperature on blister damage and permeability was investigated for sealing materials used conventionally for high pressure equipment.

In this study, in order to relax the pre-cooling regulations at hydrogen fueling stations, we develop a software algorithm to simulate an actual hydrogen fueling process to Fuel Cell Vehicle (FCV) tanks. The simulation model in the software consists of the same filling equipment found at an actual hydrogen fueling station. Additionally, the same supply conditions (pre-cooling temperature, pressure and mass flow rate) as at a hydrogen fueling station were set to the simulation model. Based on the supply conditions, the software simulates the temperature and pressure of hydrogen in each part of filling equipment. In order to verify the accuracy of the software, we compare the temperature and pressure simulated at each stage of the filling process with experimental data. We show that by using the software it is possible to accurately calculate the hydrogen temperature and pressure at each point during the fueling process.

Outwardly propagating stoichiometric flames of H2/CH4/air were studied in a constant volume fan-stirred combustion chamber in order to investigate the effects of hydrogen concentration on the turbulent burning velocities. The experiments were conducted at mixture temperature of 350 K and mixture pressure of 0.10 MPa. The mole fraction of hydrogen in the binary fuel was varied from 0 to 1.0 for turbulence intensities equal to 1.23, 1.64 and 2.46 m/s. Laminar flames of the mixtures were first investigated to obtain the unstretched laminar burning velocities and the associated Markstein numbers. The unstretched laminar burning velocity increased non-linearly with increase in hydrogen fraction. The Markstein number and the effective Lewis number of the mixtures varied non-monotonically with hydrogen mole fraction. The Markstein number was used to investigate the influence of thermo-diffusive effects on the turbulent burning velocity.

Compressed hydrogen gas is currently the most popular choice for a fuel storage mode for fuel cell vehicles (FCVs). For the practical design of suitable vessels and hydrogen filling stations, it is necessary to be able to accurately predict the temperatures of the vessel wall and gas during filling. Recently, Monde et al.[ 1 ] proposed a thermodynamic model for the gas in the vessel during filling. In this paper, on the basis of the Monde et al. model, the temperature of the precooled hydrogen and the filling time are analyzed for a practical vessel and hydrogen filled range. Equations predicting them are derived using the calculated values.

The present study is performed to examine experimentally the turbulent burning velocity characteristics of lean hydrogen mixtures with attention to the local burning velocity. The special mixtures, having nearly the same laminar burning velocity with different equivalence ratios Ф=0.3~0.9, are prepared. The measured turbulent burning velocities at the same turbulence intensity show to large increase as Ф decreases until about 0.5. Those, however, do not show such large increase when Ф becomes lower than about 0.5. This phenomenon is discussed by the estimated mean local burning velocity taking account of preferential diffusion, tomograms of turbulent flames and estimated Markstein number.

For safe and fast refueling hydrogen to fuel cell vehicles (FCVs) at hydrogen refueling stations (HRSs), a refueling protocol is under discussion at SAE J2601 to be a global standard. In order to realize such a standard, we have to estimate the relation between gas temperature and pressure during a refueling and for an accurate estimation we have to correctly understand the thermal characteristics of hydrogen tank. Fast refueling test data has been offered by BMW-Powertech, some test cases have been analyzed by a simulation model developed by Monde et al. It reveals that the hydrogen temperature at the end of refueling does not exceed 85°C for these analyzed cases. The effect of the pressure drop between storage bank and hydrogen tank was negligible on the gas temperature at the end of refueling, although the gas temperature shows different profile depending on the pressure drop.