Visualization of explosion characteristics of methane-air mixtures with different ignition positions and vent areas in a large-scale venting chamber

Xing, Huadao; Qiu, Yanyu; Sun, Shicai; Wang, Mingyang; Li, Bin; Xie, Lifeng

doi:10.1016/j.fuel.2020.118380

Cited by 53 publications

(20 citation statements)

References 60 publications

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“…Through experiments and simulations of methane‐air mixing explosions in large pipes, Li et al 11 found that the existence of vents greatly reduced the peak pressure. Xing et al 12 studied and analyzed the relationship between flame behavior and internal pressure under different experimental conditions by using 4.5 m 3 stainless steel equipment to conduct gas and air explosion tests. Wang et al 13 found that as the intensity of turbulence increases, the combustion propagation rate increases, as well as the maximum combustion pressure and pressure rise rate.…”

Section: Introductionmentioning

confidence: 99%

Study on characteristics of methane explosion flame and pressure wave propagation to the non‐methane area in a connected chamber

Liu

Wang

et al. 2021

Fire and Materials

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This study is aimed at investigating the characteristics of CH 4 explosion diffusion and propagation to the non-methane area. The CH 4 explosion pressure and flame were tested with the aid of a self-built horizontal pipeline system. On this basis, the flame images, photoelectric signals, and pressure propagation laws during explosions of methane with different volume fractions in the pipeline were obtained. The experimental research results indicate that an obvious secondary explosion pressure occurs at L/D = 3.5. After the explosion pressures at different positions along the entire pipeline reach the peak values, they experience varying degrees of oscillations. The maximum explosion pressure in the non-methane zone may occur at different length-to-diameter ratios. When the volume fraction of CH 4 is larger, the maximum explosion pressure occurs farther. However, the explosion pressure at the end of the pipeline is lower than that at the explosion source. The flame intensity and flame duration of methane explosion are remarkably enhanced at L/D = 17.5 and then become gradually weakened in the non-methane area. The variations of explosion pressure are always prior to those of flame signal. CO and CO 2 are the main toxic and harmful gases produced by methane explosions, and high-concentration (13% in this experiment) methane explosions produce a small amount of hydrocarbon gases such as C 2 H 4 and C 2 H 6 . The volume fractions of the gases produced decrease with the increase in the distance from the explosion source. The research results boast great significance for suppressing methane explosions and their propagation in the pipeline.

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Section: Introductionmentioning

confidence: 99%

Study on characteristics of methane explosion flame and pressure wave propagation to the non‐methane area in a connected chamber

Liu

Wang

et al. 2021

Fire and Materials

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“…The experimental system consists of an ignition system, an intake system, an explosion chamber, a high-speed camera, an infrared camera, and a data acquisition system (Figure ), which is similar to those used in existing research of the authors , and will be briefly described in the context of the current trial. A square stainless chamber with a volume of 1.5 m × 1.5 m × 2.0 m and a vent area of 0.8 m × 0.8 m was constructed (Figure (a)).…”

Section: Methodsmentioning

confidence: 99%

“…Third, after charging methane in V1 to V2 based on the gas state equation, methane at a concentration of 9.5 vol % was employed, corresponding to 1069 kPa in V2 in each test, and then the outlet valve on the wall of the chamber was opened; meanwhile, the menthane in V2 was completely charged into the V3 in the chamber. The V3 was pulled out from the chamber via the inlet, then all outlet and inlet valves were closed, the methane and air in the chamber were mixed by the explosion-proof fan to allow work for 3 min, and the chamber was allowed to remain static for 3 min before ignition to maintain the methane–air mixture at a low and consistent level in the chamber. , The turbulence level was measured by a hot wire anemometer with a measuring range of 0–20 m/s (405i, Testo SE & Co. KGaA, China), which is based on our previous study, and then the methane concentration was further determined by the equation CH 4 % = 1 – O 2 %/21%, where O 2 % was obtained by the oxygen sensors with the accuracy of 0.1 vol % (AO2PTB-18.10, City, UK) and 21% refers to the oxygen concentration in the air. Finally, a synchronous control unit was adopted to trigger the data acquisition system, ignition system, infrared camera, and high-speed camera.…”

Section: Methodsmentioning

confidence: 99%

Experimental Study of External Flame Evolution and Temperature Characteristics after a Methane Explosion in a Rectangular Chamber

Xing

et al. 2023

ACS Omega

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A series of methane-vented explosions were experimentally investigated in a 4.5 m3 rectangular chamber at P 0 = 100 kPa and T 0 = 298 K, and the effects of ignition positions and vent areas on the external flame and temperature characteristics were studied. The results indicate that the vent area and ignition position significantly affect external flame and temperature changes. The external flame is portioned into three stages: an external explosion, a violent flame jet with a blue flame, and a yellow flame venting. The temperature peak first rises and then reduces with increasing distance. Rear ignition produces the largest flame lengths and highest temperature, while front ignition leads to the shortest flame and smallest temperature peak. The maximum flame diameter occurs at central ignition. As vent areas increase, the coupling effect of the pressure wave and the internal flame front weakens and the diameter and peak of the high-temperature peak increase. These results can offer scientific guidance for designing disaster prevention measures and evaluating explosion accidents in buildings.

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“…Explosion venting depends strongly on various boundary conditions and on the physical environment. The influence of the size of an explosion venting surface and the ignition position on the characteristics of natural gas explosion venting was investigated by Xing et al (2020). Bao et al (2016) studied the effects of gas concentration and opening pressure on the transient state of vent pressure during a natural gas explosion.…”

Section: Introductionmentioning

confidence: 99%

Numerical study of external explosion characteristics induced by indoor natural gas vented explosion

Pang

Yang

2021

HFF

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Purpose The purpose of this paper is to ascertain the harm to personnel and equipment caused by an external explosion during natural gas explosion venting. The external explosion characteristics induced by the indoor natural gas explosion are the focal points of the investigation. Design/methodology/approach Computational fluid dynamics technology was used to investigate the large-scale explosion venting process of natural gas in a 6 × 3 × 2.5 m room, and the characteristics of external explosion under different scaled vent size (Kv = Av/V2/3, 0.05, 0.08, 0.13, 0.18) were numerically analyzed. Findings When Kv = 0.08, the length and duration of the explosion fireball are 13.39 and 450 ms, respectively, which significantly expands the degree and range of high-temperature hazards. The suitable flow-field structure causes the external explosion overpressure to be more than twice that indoors, i.e. the natural gas explosion venting overpressure may be considerably more hazardous in an outdoor environment than inside a room. A specific range for the Kv can promote the superposition of outdoor rupture waves and explosion shock waves, thereby creating a new overpressure hazard. Originality/value Little attention has been devoted to investigating systematically the external explosion hazards. Based on the numerical simulation and the analysis, the external explosion characteristics induced by the indoor large-scale gas explosion were obtained. The research results are theoretically significant for mitigating the effects of external gas explosions on personnel and equipment.

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Visualization of explosion characteristics of methane-air mixtures with different ignition positions and vent areas in a large-scale venting chamber

Cited by 53 publications

References 60 publications

Study on characteristics of methane explosion flame and pressure wave propagation to the non‐methane area in a connected chamber

Study on characteristics of methane explosion flame and pressure wave propagation to the non‐methane area in a connected chamber

Experimental Study of External Flame Evolution and Temperature Characteristics after a Methane Explosion in a Rectangular Chamber

Numerical study of external explosion characteristics induced by indoor natural gas vented explosion

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