Occurrence Of Spontaneous Ignition Research Articles

Experiment study on the pressure and flame characteristics induced by high-pressure hydrogen spontaneous ignition

A series of experiments were conducted to study the pressure and combustion characteristics of the high-pressure hydrogen during the occurrence of spontaneous ignition and the conversion from spontaneous ignition to a jet fire and explosion. Different initial conditions including release pressure (4–10 MPa), tube diameter (10/15 mm), and tube length (0.3/0.7/1.2/1.7/2.2/3 m) were tested. The variation of the pressure and flame signal inside and outside of the tube and the development of the jet flame were recorded. The experimental results revealed that the minimum ignition pressure required for self-ignition of hydrogen at different tube diameters decreased first and then increased with the extension of tubes. The minimum ignition pressure for tubes diameters of 10 mm and 15 mm is no more than 4 MPa and the length of the tubes is L = 1.7 m. The minimum release pressure required for spontaneous ignition of a tube D = 15 mm is always lower than that of a tube D = 10 mm at the same tube length. When the spontaneous ignition occurred, it did not absolutely trigger the jet fire. The transition from spontaneous ignition to a jet fire must go through the specific stages.

Experimental study on shock wave propagation and spontaneous ignition induced by high-pressure hydrogen suddenly released into T-shaped tubes

To investigate the influence of bifurcation structure in tubes on the spontaneous ignition of high-pressure hydrogen, a series of experiments were conducted. The tubes including T-shaped and straight tubes with the length of 0.7/1.2/1.7 m were tested. The burst pressure ranged from 4–10 MPa. The pressure and light signals in the tube and the external flame images were recorded. The results show that the T-shaped structure has a significant influence on the occurrence of spontaneous ignition. The critical release pressure required for self-ignition in short T-shaped tube was lower than that in straight tube, because the strong reflect shock wave near the bifurcation point heated the combustible mixtures near the contact surface. However, with the extension of the tube length, the critical pressure increased, because the distance between the leading shock and contact surface increased when the leading shock reached the bifurcation point. Consequently, the reflect shock cannot heat the combustible mixture near the contact surface, but the air instead. Besides, comparing with the straight tube, the formation of jet fire was inhibited in the T-shaped long tube (1.2/1.7 m) and the shock wave attenuated rapidly after pass through the bifurcation point.

A Numerical Study of Low Temperature Silane Combustion

A mechanism of low temperature silane combustion has been proposed in the present work based on the assumption that a trace amount of water vapor helps the occurrence of spontaneous ignition at room temperature. This assumption has been made based upon the fact that the combustion product of silane influences positively the occurrence of spontaneous ignition. Energetic calculation of the reaction path way for low temperature silane combustion also supports this assumption [Kondo et al., 1999]. A numerical model has been constructed which can interpret the spontaneous ignition limit at room temperature, the ignition delay times, and the second explosion limit of silane mixtures simultaneously.

Chain-Reaction Chemical Laser Using H2–F2–He Mixtures

Laser action was observed from HF produced in a chain reaction between H2 and F2 initiated by flash photolysis of H2–F2–He mixtures. Conditions were found for mixing the reagents at room temperature without the occurrence of spontaneous ignition.