5.1安全工程科技英语

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1. Introduction
However, a few investigations have been conducted into the effect of burst pressure or the size and shape of a discharge aperture孔 and piping on the possibility of self-ignition. Furthermore, it is not mentioned whether the self-ignition in a tube propagates outside of the tube to initiate a hydrogen-jet flame. From a safety standpoint立场，观点, it is important to be able to predict whether a sudden release of hydrogen into the atmosphere would create conditions for spontaneous ignition and formation of hydrogen-jet flame. We previously reported the self-ignition of a hydrogen jet by rapid discharge (Mogi, Kim, Shiina, & Horiguchi, 2006). In this study, sudden discharge of pressurized hydrogen gas into the atmosphere was investigated experimentally, and the influence of storage pressure, the size of the discharge aperture, nozzle length and other discharge conditions on self-ignition were examined. Further, flame propagation in the hydrogen jet in the event of self-ignition was observed.
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1. Introduction
Tanaka, Urano, Iwasaka, and Hashiguchi (1978)reported selfignition of hydrogen released abruptly into the atmosphere by a diaphragm. They used detonationtubes with a diameter of 50 mm. Lui, Sato, Tsuboi, Higashino, and Hayashi (2006) investigated, by numerical simulation, the possibility of self-ignition of a jet of hydrogen from a 70-MPa compressed hydrogen tank. Dryer, Chaos, Zhao, Stein, Alpert, and Homer (2007) demonstrates the self-ignition from sudden compressed hydrogen releases. They pointed out that the flow geometry downstream of the burst disk holder has strong effects on whether and at what minimum burst disk failure pressure selfignition would occur. Golub, Baklanov, Bazhenova, Bragin, Golovastov, Ivanov, and Voldin (2007) investigated the structure of impulse jet experimentally and numerically. They reported that selfignition was observed at a pressure less than 5MPa in the tube (5mm in diameter and 185mm in length).
INFORMATIONS FOR THE PAPERBiblioteka -2-Abstract
The phenomenon of self-ignition and explosion during discharge of high-pressure hydrogen was investigated. To clarify the ignition conditions of high-pressure hydrogen jets, rapid discharge of the high-pressure hydrogen was examined experimentally. A diaphragm隔膜 was used to allow rapid discharge of the high-pressure hydrogen. The burst pressure was varied from 4 to 30 MPa. The downstream geometry of the diaphragm was a flange and extension pipes, with the pipe length varying from 3 to 300 mm. The diameter of the nozzle喷嘴 was 5 or 10 mm. When short pipes were used, the hydrogen jet did not ignite. However, the hydrogen jet showed an increasing tendency to ignite in the pipe as the length of the pipe became longer. At higher burst pressures, a diffusion jet flame was formed from the pipe. The blast wave from the fireball formed on self-ignition of the hydrogen jet resulted in an extremely rapid pressure rise.
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1. Introduction
Hydrogen is clean energy carrier, and the development of hydrogenfueled vehicles is advancing rapidly. However, for energy-efficient use of fuel-cell vehicles, safe handling of high-pressure hydrogen storage vessels and piping is required. Hydrogen has an ignition energy as low as 0.019 mJ(mili-joule), and a wide flammability range in air (4–75% by volume of hydrogen). Early implementation of safety measures for handling compressed hydrogen is crucial至关重 要的. It is therefore necessary to collect data on safety in a range of possible accident scenarios情景, assess hazards and risks and develop mitigation measures. One of the postulated假定的 scenarios is damage to high pressure hydrogen storage facilities and consequent discharge of hydrogen. When high-pressure hydrogen is suddenly discharged into air, a shock wave compresses the air, which mixes with hydrogen at the contact surface, and this result in a temperature rise of hydrogen–air mixture, with the possibility of ignition. Wolanski and Wojcicki (1973) experimentally demonstrated selfignition of hydrogen at the boundary with oxygen when hydrogen was released into an atmosphere of oxygen by driving a piston活塞.
Self-ignition and explosion during discharge of high-pressure hydrogen ---BY Toshio Mogi, ET AL
Chen Dongliang (陈东梁) Email：chendl@ College of Mechanical and Electrical Engineering Beijing University of Chemical Technology (BUCT)