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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 order to determine the usefulness of coconut and palm oil biodiesels as alternative diesel fuel, the fuel properties, the combustion characteristics and the exhaust emissions were investigated. Therefore, the methyl esters of coconut, palm and rapeseed oils (CME, PME and RME) and the ethyl ester of palm and rapeseed oils (PEE and REE) were processed and tested using a DI diesel engine. From the experimental results, the thermal efficiency of CME is almost the same as the other test fuels and CME has the lowest HC, CO, NOx and smoke emissions among the test fuels. Also PEE has the same ignitibility as PME and the exhaust emissions of PEE are almost the same as PME. From this investigation, we can say that CME and PEE are favorable alternative diesel fuels to substitute for petroleum based diesel fuel.

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.

Combustion characteristics of the transient methane jet were investigated using a constant volume bomb. The amount of unburned fuel increased as the ignition timing was delayed. Bulk quenching was found to occur in the trailing part of the jet due to the low fuel concentration. Then the characteristics of the flame propagation into the lean region was investigated. This is accomplished by the injection of methane into the lean methane-air mixture charge, whose equivalence ratio was less than the lower flammability limit of the premixed methane-air mixture. The effects of methane concentration of the charge on the flame propagation was examined. The flame generated in the fuel jet propagated into the lean mixture charge. Though the flame propagated in the lean mixture charge for a longer duration with the increase of its methane concentration, it was quenched in the charge before it reached the chamber wall.

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.