Article
Energy & Fuels
Xianzhao Song, Jing Zhang, Quan Liu, Qiming Xu, Jiu Chen, Dan Zhang, Lifeng Xie, Bin Li
Summary: The study showed that hydrogen concentrations and vent areas have significant effects on vented hydrogen-air explosions. Increasing hydrogen concentration led to higher pressure oscillation frequency and gradual disappearance of Helmholtz oscillation. Higher hydrogen concentrations resulted in higher dynamic loading, and there is a relationship between external field hydrogen concentration and Kv, affecting explosion patterns and flame velocities.
Article
Energy & Fuels
Xianzhao Song, Jing Zhang, Quan Liu, Qiming Xu, Jiu Chen, Dan Zhang, Lifeng Xie, Bin Li
Summary: Experiments were conducted to study the effects of hydrogen concentrations and vent areas on vented hydrogen-air explosion. The results showed that the pressure oscillation frequency increased with hydrogen concentration and the Helmholtz oscillation disappeared with the increase of K-v. Higher dynamic loading was experienced at positions farther away from the vent cover. In addition, the external field had lower hydrogen concentration, and the external flame velocity was greater for rich fuel. Deflagration to detonation was easier to achieve for concentrations near 50 vol% and lower K-v.
Article
Chemistry, Physical
Lei Pang, Guoyi Li, Kai Yang, Qianran Hu
Summary: The influence of opening pressure, opening time, and scaled vent size on external explosion characteristics was studied using computational fluid dynamics technology. It was found that higher opening pressure and longer opening time result in significantly higher external explosion over-pressure intensity and shorter explosion duration. The location of the external explosion is closer to the vent with the expansion of the scaled vent size. Overall, the opening time has the most significant impact on external explosion characteristics.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Energy & Fuels
Shengchao Rui, Changjian Wang, Xinjiao Luo, Rulin Jing, Quan Li
Summary: The study investigated the effects of hydrogen concentration and ignition location on external explosions during vented hydrogen-air deflagrations in a cubic vessel. Different ignition locations resulted in variations in the maximum overpressure peaks and the impact of external explosions on flame evolution outside the vessel.
Article
Thermodynamics
Lei Pang, Qianran Hu, Kai Yang
Summary: This paper investigates the harm caused by external explosions during natural gas explosion venting. Results show that external explosions are more hazardous outdoors than indoors, and can create new overpressure hazards.
INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW
(2022)
Article
Engineering, Environmental
Yong Cao, Kanghua Gao, Bin Li, Lifeng Xie, Xuhai Pan
Summary: This paper investigates the influence of concentration, vent size, and vent burst pressure on the vented ethylene-air explosion through numerical simulation and experiments. The different phases of external flame propagation are concluded by comparing experimental photos and simulation results. The mechanism of external flame propagation is analyzed using flow velocity, velocity vector, and turbulence kinetic energy.
PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
(2023)
Article
Engineering, Environmental
Qiao Wang, Xinjiao Luo, Changjian Wang, Yi Liu, Penggan Zhou, Bing Li
Summary: Experiments on hydrogen-air vented deflagration in a smooth rectangular tube were conducted with various vent areas for different hydrogen concentrations. The effects of vent area for different hydrogen concentrations were discussed on the build-up of internal/external overpressures and the evolution of external flow field. The increase of hydrogen concentration promotes external mixture reactivity and the external overpressure.
PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
(2022)
Article
Chemistry, Physical
Wei Liu, Jin Guo, Jiaqing Zhang, Su Zhang
Summary: The study investigated the effect of vent area on the deflagration of hydrogen-methane-air mixtures in a vertical duct, finding that the nondimensional vent coefficient had varying impacts on flame evolution and pressure buildup. Different K-v values led to differences in pressure distribution inside and outside the duct, with external explosions affecting internal deflagrations to a lesser extent at higher K-v values.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2021)
Article
Chemistry, Physical
Jin Guo, Xuebiao Wang, Kai Zhang, Hao Chen, Saifeng Du, Fuqiang Yang
Summary: The experiments in this paper investigated the coupling effects of venting and nitrogen addition ratio on flame behavior and pressure evolution during hydrogen-air deflagration in a vertical duct. It was found that the nitrogen addition ratio significantly influenced the pressure-time histories in the duct, and for a certain ratio, the maximum overpressure increased with distance to the vent. Additionally, differences in overpressure between measuring points decreased with an increase in the nitrogen addition ratio.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2021)
Article
Engineering, Environmental
Jintao Xu, Xiangfeng Chen, Haipeng Jiang, Wei Gao
Summary: The flame behaviors and pressure characteristics of vented hydrogen-air explosions at elevated static activation pressures were investigated in this study. It was found that the maximum flame lengths and widths increased with the increase in venting diameters and equivalent ratios by controlling the concentration of vented unburned gas. Non-dimensional formulas were established to predict the maximum flame length and width with a relative error within 50%. The pressure curves exhibited notable oscillations, and an empirical formula was proposed to predict the internal pressure with a relative error within 25%. The mechanism of external explosions was revealed using BOS images, and it was found that the intensity of external explosions depended on the external flow field intensity and the concentration of unburned gas.
PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
(2022)
Article
Engineering, Environmental
Kai Zhang, Saifeng Du, Hao Chen, Jingui Wang, Jiaqing Zhang, Yi Guo, Jin Guo
Summary: A series of experiments were conducted to study the effect of hydrogen concentrations on flame evolution and maximum overpressure in a vented rectangular tube. The results showed that the flame behavior and pressure curves varied with hydrogen concentration. As hydrogen concentration increased, the maximum internal overpressure initially increased and then decreased, while the maximum external overpressure continued to increase.
PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
(2022)
Article
Engineering, Environmental
Shengchao Rui, Quan Li, Jin Guo, Xuxu Sun
Summary: This study experimentally investigated the effect of low vent burst pressure on methane-air deflagrations in a rectangular vessel, observing four different overpressure peaks and monitoring flame behaviors at each peak. The results showed that vent burst pressure affects P-open and P-acc, while P-out and P-ext are independent of vent burst pressure. Double flame accelerations were observed due to vent rupture and flame venting. Predictions reasonably agreed with experimental data, with discrepancies decreasing as vent burst pressure increased. Predicted maximum peak overpressure and external flame length were slightly larger than experimental values, providing better guidance for safe design and risk assessment in explosion venting.
PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
(2021)
Article
Chemistry, Physical
Quan Li, Shengchao Rui, Xinjiao Luo, Changjian Wang
Summary: This study investigated the effects of hydrogen concentration, ignition location, and obstacles on vented hydrogen-air explosions. Results showed that obstacles changed the flame propagation inside the container and increased the flame area, promoting the reaction. Existing engineering models over-predicted the maximum reduced explosion pressure for high-reactivity mixtures.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2021)
Article
Energy & Fuels
Qiuju Ma, Ya He, Yuhao Guo, Mingyu Zhong, Juncheng Shao, Zhaokun Zhang, Jianhua Chen, Jingfeng You
Summary: Explosion-vent area has a significant impact on the intensity of external explosions, with larger vent areas resulting in more powerful explosions and smaller vent areas leading to weaker external explosion intensity but higher internal pressure values.
Article
Energy & Fuels
Chunhua Wang, Jin Guo, Haozhe Wang, Hanwen Zhang, Jiahan Wu
Summary: This study investigated the effects of hydrogen ratio (x) on the vented deflagration of hydrogen/methane/air mixtures. Experimental results showed that the secondary explosion in the relief duct significantly affected the venting process, and the pressure peak in the relief duct was higher than the maximum explosion overpressure in the vessel when x > 0.8. Various pressure peaks could be distinguished in the vessel when x <= 0.8, and only one pressure peak formed when x > 0.8. The average maximum explosion overpressure in the vessel increased monotonically with increasing x, while the maximum rate of pressure rise in the vessel was much lower than that in the duct for higher x values.