Physical Explosion Research Articles

Inhibition effect of inert gas jet on gas and hybrid explosions caused by thermal runaway of lithium-ion battery

When lithium-ion batteries undergo thermal runaway in a confined space, the released gases and/or vapors or dust particles can lead to an explosion. An 8L cylindrical experimental vessel was constructed to study the inert effect of inert gases on battery-vented gas (BVG) in a confined vessel. Firstly, the inhibition effect and inert mechanism of CO2 and N2 on BVG explosion were analyzed by experiments and simulation software. The results show that the inert effect of CO2 on the BVG is significantly better than that of N2. This is because CO2 is not only better than N2 in physical explosion inhibition, but also participates in the chemical reaction. Secondly, the effect of the release of high-pressure CO2 gas on the explosion of the BVG in a closed container was simulated, showing that when the BVG is near the lower explosive limit, the CO2 jet will significantly increase the rate of explosion pressure rise of the BVG. This suggests that the inhibition effect of the CO2 jet is not as good as in premixed conditions. Finally, it is found that the inhibition effect of CO2 on the hybrid explosion is better than that of CO2 jet on the BVG. Since CO2 makes oxygen insufficient, leading to a reduction in the amount of graphite dust burned. The graphite dust and CO2 have a synergistic inhibition effect on the hybrid explosion. The above findings can provide a reference for the lithium-ion battery explosion inhibition method in the process industry.

Evaluating the moderating role of management inspection between safety hazards in hospital working conditions: A study of hospitals in Islamabad

The study identifies the relationship between safety hazards and hospitals working conditions. The management inspection role supported by the management in hospitals is identified to bring safety measures precautions and effectiveness for the healthcare staff and make the hospital working conditions better. The hospital management inspection role helps to accomplish occupational safety and better working conditions. The objective of this study is to identify the relationship of management inspection role in tackling with the safety hazards to find out working conditions in Al-Shifa International hospital and Pakistan Institute of Medical Sciences hospital. The study used various statistical tests like Pearson’s correlation and KMOs Bartlet’s test to evaluate the predictors of safety barriers, working conditions and management inspection role. Data was gathered using research questionnaire and the response rate was 73%. Among the 500 respondents, 75% were males while 25%were females. The age range was 40 or above years with a mean of 2.5. The reliability analysis for the constructs is in the acceptable range. The management lacking in providing the safety information rated as 0.61 correlation matrix. The medical doctors’ responded noise as the most detrimental factor resulted with 0.70 communality and lack of health facility comes as 0.61. The structure matrix shows biological hazards rated as 0.66 and physical explosion hazards rated as 0.70 which is analyzed through KMO Bartlet’s test. The safety hazards existence in the hospitals calls upon the attention on conducting research on inspection, detection and reporting of the hazards.

Cloud Formation by Supernova Implosion

The deposition of energy and momentum by supernova explosions has been subject to numerous studies in the past few decades. However, while there has been some work that focused on the transition from the adiabatic to the radiative stage of a supernova remnant (SNR), the late radiative stage and merging with the interstellar medium (ISM) have received little attention. Here, we use three-dimensional, hydrodynamic simulations, focusing on the evolution of SNRs during the radiative phase, considering a wide range of physical explosion parameters ( nH,ISM∈0.1,100cm−3 and ESN∈1,14×1051erg ). We find that the radiative phase can be subdivided in four stages: A pressure-driven snowplow phase, during which the hot overpressurized bubble gas is evacuated and pushed into the cold shell; a momentum-conserving snowplow phase that is accompanied by a broadening of the shell; an implosion phase where cold material from the back of the shell is flooding the central vacuum; and a final cloud phase, during which the imploding gas is settling as a central, compact overdensity. The launching timescale for the implosion ranges from a few 100 kyr to a few Myr, while the cloud formation timescale ranges from a few to about 10 Myr. The highly chemically enriched clouds can become massive (M cl ∼ 103–104 M ⊙) and self-gravitating within a few Myr after their formation, providing an attractive, novel pathway for supernova-induced star and planet formation in the ISM.

Research on physical explosion crater model of high-pressure natural gas pipeline

In this study, Hypermesh and LS-DYNA numerical simulation software are used to build a multi domain coupling model of natural gas pipeline, including soil, pipeline, TNT explosive and air domain, and the non-reflection boundary conditions are set for the model. The TNT equivalent method is used to convert the physical explosion amount of natural gas pipeline into 1387.38 kg TNT explosive amount. The simulation results show that the physical explosion of pipeline forms an approximate elliptical crater with a width of 12.68 m and a depth of 4.12 m; the TNT equivalent of the model is corrected by comparing the crater simulation value and the size value of the crater calculated by the PRCI empirical formula under the same laying condition, and the correction coefficient is selected as 0.9, and the corrected TNT equivalent is 1248.64 kg; the modified model crater size is 3.72 m deep and 12.66 m wide, compared with the crater size obtained from the field test, the error of crater depth and width calculated by the modified model simulation is 5.7% and 15.5% respectively.

Surrogate Model for the Effect of Charge State in Lithium-ion Battery Fires

Recently, the demand for eco-friendly energy sources, including batteries, has increased rapidly owing to growing climate and environmental problems. However, battery fire accidents are also increasing, and many researchers are focusing on the safe use of batteries and their flammability characteristics. Owing to the multiple battery types, conducting experiments is difficult in all cases, so various methods to model battery fires are being attempted. This study focuses on the effect of charge states and models surrogate fuels for battery thermal runaway. Three surrogate fuels were selected based on the battery components, and a method of increasing the oxygen concentration was adapted to model the effect that occurs when the charge states of a battery fire increases. As a result, the temperature and pressure increased in all cases, and it appears that the explosion caused by the battery thermal runaway can be simulated by the model. One of the results of this study is that ethane exposed to a high temperature not only contributes to the physical explosion of the battery but also increases the risk of chemical explosion as it decomposes in to H<sub>2</sub> and CH<sub>4</sub> .

Study on the inhibition effect and mechanism of N2 twin-fluid water mist with modified chloride compounds on LPG explosion

In order to develop environmontal friendly and high efficient LPG explosion inhibitors, experiments were carried out to investigate the impact of AeO9 (fatty alcohol polyoxyethylene ether) and Sicare2235 (silicone surfactant) surfactants on the suppression effect of N2 twin-fluid water mist containing modified chloride compounds on 6 % LPG/air explosion. Results showed that: The addition of a single surfactant can significantly reduce the surface tension of the droplets and improve the explosion suppression efficiency of N2 twin-fluid water mist containing chloride additives. However, chloride additives have selectivity towards surfactants. There are obvious differences in the synergistic inhibition effect of different chlorides and surfactants. Under the combination of 0.6 % AeO9, 0.06 % Sicare2235 surfactants and chloride additives, the increase in surface tension will weaken the physical explosion suppression effect and lead to the phenomenon of explosion enhancement. The results of chemical kinetics simulations indicate that, in comparison to a single explosion suppressant, the chlorine-containing compound N2 twin-fluid water mist effectively lowers the adiabatic flame temperature and the concentration of key free radicals H, OH and O. The reaction CH3 + H + M = CH3OH + M plays a pivotal role in reducing the adiabatic flame temperature during LPG explosion.

Study on physical explosion equivalent of large diameter and high pressure natural gas pipeline

High pressure natural gas pipelines are prone to material failure and explosion due to various reasons. Over the years, scholars have done in-depth research on the process of chemical explosion. In this paper, the energy components of high-pressure trunk natural gas pipeline under normal operation state were derived. Based on the assumption of adiabatic non isentropic, the pressure distribution in the pipeline within a period of time after the pipeline cracks was derived, and the energy released by the physical explosion of the pipeline was further derived. To verify the theoretical results, an original size pipe explosion experiment was organized, and the pressure distribution obtained from the experiment was found to be in good agreement with the theoretical calculation results. Through the crack propagation time and the duration of ground motion obtained from the experiment, the range of the duration of the pipeline burst crack impact was obtained, and the equivalent range of the pipeline explosion was further calculated. At the same time, through the regression analysis of ground motion, the equivalent of the pipe explosion in this experiment was about 177 kg TNT, which was consistent with the theoretical results. Further, the theoretical model and experimental results were verified by numerical simulation, and deeply studied the influence factors of buried depth on the explosion equivalent, as well as the relationship between the environment of the pipeline and the explosion damage mode and hazard range of the pipeline. The research results of this paper give the calculation method and magnitude range of physical explosion equivalent of high-pressure trunk natural gas pipeline. It provides a reference for the formulation of safety standards for high-pressure trunk natural gas pipelines and inert gas pressure vessels.

Coupling effect of multiple factors on the crater size of physical explosion in high-pressure natural pipelines

he physical explosion of high-pressure natural gas pipelines causes craters and shock waves, which pose a serious threat to the people and buildings in the surrounding area. This study utilized HyperMesh and LS-DYNA software to establish a physical explosion model for high-pressure natural gas pipelines. The physical explosion processes for pipe diameters of 813, 1016, 1219, and 1422 mm under six burial depths and three soil conditions were calculated. Based on the simulation results, the equations for the variation in crater size were fitted, and the curves of the relationships between crater size and influencing factors were fitted to analyze the coupling effect of multiple factors on the crater size variation. The results showed that the crater size was positively correlated with the pipe diameter. As the diameter of the pipe increased, the length, width, and depth of the crater increased by 64.2, 53.8, and 32.1 %, respectively. The larger the burial depth was, the smaller the crater length and width were. However, the crater depth first increased and then decreased as the burial depth increased. The crater depth was the highest at a burial depth of 3 m. These findings can provide a reference for the design and safety evaluation of high-pressure natural-gas pipelines in high-consequence areas.

Актуализация руководств по безопасности в области оценки риска аварий на производственных объектах

Changes in the legislation in the field of industrial safety, as well as the experience of declaring industrial safety, developing safety cases for hazardous production facilities and other work related to risk analysis (assessment), required introduction of changes to the set of Rostechnadzor safety guidelines, most of which were developed in the period of 2013–2018. For this purpose, in agreement with Rosteсhnadzor, the specialists from the Group of Companies «Industrial Safety» (STC IS), STC «Industrial Safety» CJSC, ANO «Industrial Risk Research Agency», Fund of James Bruce) on a voluntary basis in the period of 2020–2022 prepared and sent to Rostechnadzor the drafts of amendments of 13 safety guides, which are currently approved. The article presents a classification of the above safety guides by content and considers a set of methods for accident risk analyses. The changes are presented in these guides related to the legal requirements for terminology, the need to make the set of safety guides more systematic. The algorithms for calculating risk indicators and affected areas were refined, the most significant of which can be distinguished: taking into account the variable clutter at the location of the fuel-air mixtures cloud, proceeding from the modern ideas about the assessment of the explosion consequences; including in the calculation of explosion parameters a model of computational gas dynamics, as well as the model designed for numerical simulation in the ejection of the jet section of the flow; actualization of the parametric models for calculating the effects of shock wave propagation in a physical explosion. The main directions are proposed concerning further improvement of the methodological support of risk analysis at the hazardous production facilities.

Оценка изменения безопасных расстояний при нарушениях регламента испытаний газопроводов

Accidents occurring during the process of gas pipelines testing are characterized by the impossibility of the occurrence of thermal radiation of jet flames and fire in the pit-damaging factors dominating the operation stage of the facility. In addition, what is happening cannot be accompanied by the baric effect of chemical explosions. However, taking into account the significant increase in pressure in the gas pipeline during pneumatic tests, such damaging factors of the accident as the scattering of fragments, the pressure effect of a high-speed jet and the baric effect of the primary shock wave are amplified. The issue of ensuring the safety of personnel present near the test site becomes relevant. As a result, the need occurs to determine precisely the safe distances to the gas pipeline. Protective zones for the population are also established based on the identified safe distances. Within the framework of the risk-oriented approach, the procedure for determining safe distances is reduced to calculating the distances at which damaging factors lose their damaging properties. When assigning protective zones, it is required to consider the possibility of changing the indicator under consideration, due to probable errors of personnel in the preparation and conduct of tests. Even non-critical miscalculations can significantly affect the determination of a safe distance. The article presents an assessment of the relative values of safe distances, taking into account possible violations of the regulations regarding backfilling and filling with water or air, during hydraulic or pneumatic tests of gas pipelines. Relative values of safe distances are also established in terms of the scattering of fragments and the impact of an air shock wave of a physical explosion on people and building objects.

Theoretical analysis and experimental study on physical explosion of stratospheric airship envelope

The shock wave released from physical explosion of a pressurized stratospheric airship can produce serious damage to the environment. Shock wave overpressure can measure the degree of damage that an explosion can cause to such things as buildings and the human body. To obtain the overpressure from an airship envelope explosion, explosion energy must first be conducted. Explosion energy is derived based on Brode’s equation, Brown’s equation, and Crowl’s equation. An equivalent TNT computational model is then applied to calculate the overpressure of the explosion energy. In order to verify the accuracy of the computational model, a ground test must be conducted. The experimental result shows that a computational model based on Crowl’s equation is more accurate than the other two. Finally, the effect of geometric scale ratio, pressure difference, and the gas of the explosion overpressure is discussed. This paper can provide a relatively effective calculation method for shock wave overpressure for an airship envelope explosion.

A Systematic Research on System Recovery Based on Improved Genetic Algorithm and Quotient Resilience Model Under Attack and Damage

The vulnerability of the current network has become an urgent problem to be solved. The focus of network protection should be shifted from traditional network protection to the direction of effective recovery even after being attacked and damaged, and then, the concept of resilience came into being. This paper selects physical explosion attacks to establish damaged network. An improved system resilience recovery strategy is established which considers task importance and time efficiency. Aiming at the initial population is too random, easy to mature and with poor solution, this paper improves genetic algorithm by new greedy model in population initialization and head-to-head mutation operator. Simulation shows that the improved genetic algorithm is better and more stable, the improved quotient model is more effective in system resilience recovery measured by index-E proposed in this paper.

Approval of a computational method for determining thermal loads during accidents accompanied by fireballs

Introduction. Large fires are quite often accompanied by the formation of fireballs (OSH), which create significant thermal loads. As a result of the fire coverage of a container containing an overheated liquid, a physical explosion occurs, which releases a significant amount of fuel forming a fireball. This phenomenon is dangerous because, with a short lifetime, it is capable of causing thermal injuries over considerable distances. The existing methods of predicting the consequences of a fireball, set out in various domestic regulatory documents and foreign literature, do not fully reflect the possible values of thermal loads. In this regard, a computational method for determining thermal loads was developed, taking into account the movement of the fireball.Goals and objectives. The purpose of this study is to test the developed computational methodology for determining thermal loads, which takes into account the kinematic characteristics of the fireball. The following tasks were solved in the study:● check the operability of the fireball lifting model;● to conduct a comparative analysis of thermal loads according to the developed methodology with the results of calculation of domestic and foreign methods;● conduct a computational experiment on the effect of air mobility (wind effect of 7 m/s) on thermal loads.Research methods. To check the operability of the OSH lifting model, footage of the formation of a fireball was used. According to the shooting frames, the position of the fireball in space and its kinematic characteristics were tracked. Using kinematic parameters, thermal loads were determined. To assess the adequacy of calculations of thermal loads, a comparative analysis of the results of calculations of the developed computational methodology with the results of calculations using existing domestic and foreign methods was used. To substantiate the application of the developed computational methodology for determining thermal loads, taking into account the kinematic parameters of the fireball, a computational experiment was conducted using the MATLAB software and computing complex.Results and their discussion.The results of the calculation of kinematic parameters are satisfactorily correlated with the results of mathematical modeling. The obtained values of thermal loads according to the developed computational methodology are in satisfactory agreement with the results of calculations according to existing domestic and foreign methods. Based on the calculations performed in the article, it is shown that a change in gas dynamic flows (wind demolition) leads to a significant change in the damaging factors of fireballs that are formed during fires in emergency situations.Conclusions. The results of the research made it possible to assess the adequacy of the performance of the improved computational methodology for determining thermal loads in accidents accompanied by fireballs, as well as to justify the relevance of the application of the developed method.

Explosion behavior investigation and safety assessment of large-format lithium-ion pouch cells

Large-format lithium-ion (Li-ion) batteries with high energy density for electric vehicles are prone to thermal runaway (or even explosion) under abusive conditions. In this study, overcharge induced explosion behaviors of large-format Li-ion pouch cells with Li[Ni0.8Co0.1Mn0.1]O2 cathode at different current rates (C-rates) (0.5C, 1C, 2C) were investigated. The explosion characteristics of the cells were elucidated by discussing the evolution of the cell voltage, the surface temperature and the shock wave pressure. Generally, the whole overcharge process could be divided into four stages according to the evolution of several key parameters and the overcharge behaviors; the overcharge C-rate has a great influence on cells’ thermal behaviors. The experimental results showed that the thermal runaway process of Li-ion cells caused by overcharging consisted of two kinds of explosions, physical explosion and chemical explosion. The existence of observable negative pressure zone in the pressure curves indicated that the Li-ion cells are not a self-supplying oxygen system during the explosion. Further, the explosion dynamics parameters were matched. An explosion TNT-equivalent conversion strategy that depended on the pressure of the shock wave was utilized to evaluate the released energy and its hazards. In addition, with respect to the overcharge of Li-ion pouch cells, a safety assessment method and a safety management method were proposed based on the explosion behaviors. From the perspective of battery safety, this study is of great significance for the safety design of Li-ion cells and can provide guidance for engineers to optimize the safety function of battery packs.

A CFD analysis of liquefied gas vessel explosions

Hydrogen is one of the most suitable candidates in replacing fossil fuels. However, storage issues due to its very low density under ambient conditions are encountered in many applications. The liquefaction process can overcome such issues by increasing hydrogen’s density and thus enhancing its storage capacity. A boiling liquid expanding vapour explosion (BLEVE) is a phenomenon in liquefied gas storage systems. It is a physical explosion that might occur after the catastrophic rupture of a vessel containing a liquid with a temperature above its boiling point at atmospheric pressure. Even though it is an atypical accident scenario (low probability), it should be always considered due to its high yield consequences. For all the above-mentioned reasons, the BLEVE phenomenon for liquid hydrogen (LH2) vessels was studied using the CFD methodology. Firstly, the CFD model was validated against a well-documented CO2 BLEVE experiment. Secondly, hydrogen BLEVE cases were simulated based on tests that were conducted in the 1990s on LH2 tanks designed for automotive purposes. The parametric CFD analysis examined different filling degrees, initial pressures and temperatures of the tank content with the aim of comprehending to what extent the initial conditions influence the blast wave. Good agreement was shown between the simulation outcomes and the LH2 bursting scenario tests results.

ДЕЙСТВИЕ ИСКРОВОГО ИСТОЧНИКА ЗАЖИГАНИЯ НА ВСПЕНЕННЫЕ ТОПЛИВА

Experimental research results on the initiation of foamed oil products by electric-discharge plasma are presented. The experimental research simulates the impact of electrostatic charges on foamed oil products and makes it possible to determine their minimum ignition energy. Foamed diesel fuel was chosen as the object of the research. The article shows that when a foamed fuel mixture is exposed to a high-voltage discharge, a physical explosion of the mixture occurs. In that case, there is no ignition of the mixture. The dielectric strength of the foamed fuel mixture is close to the dielectric strength of air

A combined fluid-dynamic and thermodynamic model to predict the onset of rapid phase transitions in LNG spills

Transport of liquefied natural gas (LNG) by ship occurs globally on a massive scale. The large temperature difference between LNG and water means LNG will boil violently if spilled onto water. This may cause a physical explosion known as rapid phase transition (RPT). Since RPT results from a complex interplay between physical phenomena on several scales, the risk of its occurrence is difficult to estimate. In this work, we present a combined fluid-dynamic and thermodynamic model to predict the onset of delayed RPT. On the basis of the full coupled model, we derive analytical solutions for the location and time of delayed RPT in an axisymmetric steady-state spill of LNG onto water. These equations are shown to be accurate when compared to simulation results for a range of relevant parameters. The relative discrepancy between the analytic solutions and predictions from the full coupled model is within 2% for the RPT position and within 8% for the time of RPT. This provides a simple procedure to quantify the risk of occurrence for delayed RPT for LNG on water. Due to its modular formulation, the full coupled model can straightforwardly be extended to study RPT in other systems.

Analysis of ‘5.29’ blast furnace burst accident of Fangda special steel

On May 29, 2019, a blast furnace explosion occurred in the iron making plant of Fangda Special Steel Technology Co., Ltd. in Qingshanhu District, Nanchang City, Jiangxi Province. The corrugated compensator of No.2 blast furnace gas riser burst, resulting in 6 deaths, 4 injuries and direct economic losses of more than 27.24 million yuan. Through the analysis of the amount of water drawn from the top of blast furnace, this paper concludes that this is a physical explosion caused by overheating, rapid boiling expansion and over-pressure of liquefied water. Through the qualitative evaluation of the accident by Bow-tie model, the specific causes and consequences are analyzed, and the physical model is used to carry out a further quantitative analysis of the consequences, the hazard area is determined, and the countermeasures to prevent the burst accident of corrugated compensator are put forward, which is helpful to prevent the recurrence of such accidents.

An enhanced weighted essentially non-oscillatory high order scheme for explosion modelling

Physical explosion causes large damages in the process industry and quite often escalates to chemical explosions. The shock waves generated by such events are challenging to model and they must be numerically captured without spurious oscillations in order to make an accurate estimative of the accidental effects. In this context, this paper investigates how a new high order numerical scheme models the physical explosion. We have considered a confined explosion in a spherical vessel and blast load throughout pipelines as the framework to investigate the performance of the numerical scheme. The developed numerical approach considers the effect of less smooth substencils when there is a discontinuity inside the stencil based on the local Mach number what avoids oscillations and instability. The numerical solution of the fundamental equations is coupled with the Modified Colebrook-White formulation in order to consider the blast load through the pipeline. Shock waves from experimental data and analytical model are used to validate the proposed model. The research provides an efficient method for prediction of blast loads from spherical vessels rupture to an open atmosphere and in pipelines.

An experimental study of water BLEVE

A boiling liquid expanding vapour explosion (BLEVE) is a physical explosion caused by a sudden rupture of a vessel containing superheated liquid. A BLEVE can occur with many types of fluids and is not an exclusive phenomenon for flammable liquefied gases such as propane or butane. Other superheated liquids suffering a fast depressurization at high temperature may entail a BLEVE, such as water in steam generation systems. Several pieces in literature suggest that superheated water may produce a BLEVE, but little experimental data can be found on that topic.The aim of this work was to perform water BLEVE tests with a 14 L pressure vessel designed on purpose to produce high superheated liquid water (290 °C; 75 bar) and to trigger a BLEVE through calibrated rupture disks. Pressure sensors were set in the vessel to measure the internal phase change pressure dynamics and other aerial overpressure sensors were put around the relief rupture disk to capture the blast wave. Temperature of water was also recorded, and a fast camera (Phantom V2512) was used to see the phenomenon.Data show clearly the pressure recovery due to rapid boiling in the vessel. Explosive boiling did not add additional internal pressure force on the containment. Two main blast waves were observed, they were strongly related with outlet orifice area but little dependant on filling ratio. The two phase jet reached a 20 m range.