| Summary: | 碩士 === 國立高雄第一科技大學 === 環境與安全衛生工程研究所 === 101 === Hydrogen is commonly used in the petrochemical, semiconductor and optoelectronic plants as a reducing agent. It is also the cleanest fuel which produces only water upon combustion and no other greenhouse gases.
Hydrogen is not a pyrophoric gas. However, Wolanski and Wojcicki''s [1972] used a shock tube to release hydrogen into and observed autoignition in the contact surface of hydrogen and air. It is suspected that adiabatic compression leading to temperature rise caused the ignition. Kim et al. [2013] studied the shock and flow structure inside the flow channel with the aids of double glass window and two high speed cameras, and confirmed that shock compression was the cause of ignition. Chen et al.[2013] used a similar system as those of Kim et al. [2013] but with a rectangular channel that similar to real cracks to record the shock wave and shock structure. Different shock structure was observed in the rectangular channels. Thus, it is intended to measure the pressure inside the channel and to compare with the shock structure.
The results can be classified into no ignition; ignition but without jet flame outside the channel, and ignition with jet flame outside the channel. The condition of ignition inside the channel cannot be resolved properly owing to the limitation from the channel. Comparing the two cases with ignition, it is found that the pressure inside the channel will reach a peak and then decay for the case of sustained jet flame outside channel. For the cases without jet flame outside the channel, the pressure spike was absent. The pressure spike is also found to relate to the maximum pressure rise rate. Thus, it is suspected that the pressure spike is related to the flame intensity which provides an indirect evidence for proving that the ignition and jet flame outside the channel is decided by the flame intensity inside the channel. The results will help to better understand the ignition behavior of hydrogen release.
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