Experimental studies on pressure dynamics of C^sub 2^H^sub 4^/N^sub 2^O mixtures explosion with dilution

• Published in: Applied thermal engineering Vol. 147; p. 74
• Main Authors: Shen, Xiaobo, Zhang, Ningning, Shi, Xuemei, Cheng, Xianghua
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier BV 25.01.2019
• Subjects: Adiabatic conditions; Carbon dioxide; Chemical reactions; Decomposition; Decomposition reactions; Detonation; Dilution; Experiments; Explosions; Initial pressure; Nitrous oxide; Nuclear engineering; Nuclear safety; Organic chemistry; Pressure; Pressure sensors; Radioactive wastes
• ISSN: 1359-4311; 1873-5606
• DOI: 10.1016/j.applthermaleng.2018.10.053

Safety concerns of N2O has arisen due to its extensive existence in nuclear waste and aerospace applications. In present study, the stoichiometric mixtures of C2H4/N2O with N2 or CO2 dilution were examined to know the explosion mechanism and hazard. The experiments were carried out in a standard 20-L spherical explosion vessel with pressure sensor at initial pressures of 0.2 bar, 0.35 bar and 0.5 bar. The results show that, with less than 30% dilution (N2 or CO2, in mass fraction), there exists a flame acceleration mechanism or transition to detonation with measured maximum explosion pressure approaching Chapman-Jouguet (CJ) detonation pressure. Furthermore, at initial pressure of 0.2 bar, the explosion process presents three distinct stages, while at 0.35 bar or 0.5 bar, the third stage is hard to be distinguished, which indicates less accomplished transition to detonation due to the shorter combustion duration in the vessel. Besides, both N2 and CO2 dilutions can inhibit the explosion through constraint to N2O decomposition via enhanced trimolecular reaction, O + N2 + M → N2O + M (R4). But compared to CO2, N2 is more effective in R4, which results in better inhibition effect. By contrast, with 30% or more dilution, the explosion agrees well with the prediction by chemical equilibrium method at adiabatic condition. Sharp peak (SP) and broad peak (BP) were observed and interpreted.