Fire Extinguishing Research Articles

Study on multi-field coupling characteristics of underground coal combustion and nitrogen injection parameter optimization

Underground coal fires, which are widely distributed and cause serious resource waste and environmental hazards, have become a common concern of the international community. This paper aims to reveal the mechanism of coal spontaneous combustion and the expansion law of underground coal fires. A void rate model from the goaf to the ground surface and a multi-field coupling model for underground coal fires were established. Based on which, the combustion process from the beginning of oxidation to the formation of large-scale fire of the remaining coal in goaf was analyzed. Furthermore, the evolution law of underground coal fire after nitrogen injection and the influence of different nitrogen injection parameters were analyzed. The results show that the coal spontaneous combustion can be divided into three stages: slow reaction stage (stage Ⅰ), violent combustion stage (stage Ⅱ), and stable combustion stage (stage Ⅲ), and the transformation of different stages is mainly controlled by the oxidation reaction rate of coal. To obtain the optimal parameters for nitrogen injection for fire suppression, the fire extinguishing efficiency concerning nitrogen injection time, nitrogen injection amount and nitrogen injection position, as well as the distribution law of nitrogen in rock strata were analyzed. Through range analysis, it is determined that the most effective fire extinguishing occurs with the injection rate of 0.15 m3/s in stage I, and the injection position has little influence on the fire extinguishing effect. This understanding contributes to a deeper understanding of the multi-field coupling mechanism of underground coal fires and provides a guidance for extinguishing and preventing underground coal fires.

Rational design of the temperature-responsive nonflammable electrolyte for safe lithium-ion batteries

The development of nonflammable electrolytes is critical for breaking the trade-off between the safety and energy density in Li-ion batteries (LIBs). Here, a rational design strategy of temperature-responsive nonflammable electrolytes (TRNEs) is proposed which are capable to prevent the heat accumulation and extinguish the fire efficiently during thermal runaway. Compared to the conventional phosphate- or halogen-based flame retardants, the TRNE based on low-cost and multifunctional methylurea (MU) was demonstrated with the lowest volatility (11.6 % weight loss) below 250 °C, and the highest efficacy to extinguish the fire at >210.4 °C through heat absorption, inert gases generation and char layer formation. In addition, the developed MU-based TRNEs enable higher stability and rate capability of LIBs compared to various nonflammable electrolytes. A Li||LiFePO4 (LFP) cell employing MU-based TRNE achieved higher stability (94.9 % capacity retention for 1500 cycles) than commercial electrolyte. A Ni-rich Li||LiNi0.8Mn0.1Co0.1O2 (NMC811) system was demonstrated with superior rate capability and high stability for 700 cycles (2.72 months) with the capacity retention of 89.9 %. Combining low cost and volatility, as well as high stability, rate capability and fire extinguishing efficacy, we demonstrate a promising design strategy to improve the battery safety for high-energy-density LIBs.

FIRE DETECTION USING AI

Fires are one of the biggest challenges in the world right now, due to the global warming that the planet is currently suffering from. We all know what fires are and what they are capable of causing great damage, whether to humans, animals, or other forms of life. Fires spreading increasingly around the world due to increasing global warming, it has become imperative to develop an intelligent system that detects fires early, using modern technology. Therefore, we used one of the artificial intelligence techniques, which is machine learning, which is one of the popular methods now. Professionals have done a lot of research, experiments, and coding software to detect fires using machine learning. Image processing is a type of processing in which the input image is transformed into another image as output with certain techniques applied to it. In this concept, we will create a fire detecting device using a USB or system camera and a application and apply the concepts of IoT and Image Processing to get real time fire detection results. When the device is switched on, it continuously monitors the area Infront of camera for fires. This is done by using HAAR Cascade Classifier Algorithm. Once detected the system could be hooked up with either fire extinguishers to make them work independently or it could just set an alarm or send a notification to the users mobile device via GSM. The after processing possibilities are endless.

Analysis of Innovation Trends in Energy Storage Safety Technology based on Patent Data

Against the backdrop of energy transition and the large-scale development of renewable energy, the significance of energy storage technology has become increasingly prominent. Based on the data of invention patents, this paper analyzes the innovation situation of global energy storage safety technology, providing a reference basis for future patent research and industrial planning in the field of energy storage safety. Through the global and Chinese patent application volumes, the research comparatively analyzes the application situations of the main source countries and main applicants of patents, and analyzes the innovation situation of energy storage safety technology by combining research methods such as technical structure comparison and value degree comparison. The study finds that global energy storage safety innovation is in a relatively active period. China takes the leading position in the total amount of patent applications, but the proportion of patents with high value is low, and it still lags behind South Korea and the United States. Currently, the main research directions in this field worldwide mainly include battery monitoring and status monitoring, battery protection, fire detection and alarm, fire extinguishing systems, and battery pack structure design.

Simulation of a Hazardous Chemical Cascading Accident Using the Graph Neural Network

In the storage of hazardous chemicals, due to space limitations, various hazardous chemicals are usually mixed stored when their chemical properties do not conflict. In a fire or other accidents during storage, the emergency response includes two key steps: first, using fire extinguishers like dry powder and carbon dioxide to extinguish the burning hazardous chemicals. In addition, hazardous chemicals around the accident site are often watered to cool down to prevent the spread of the fire. But both the water and extinguishers may react chemically with hazardous chemicals at the accident site, potentially triggering secondary accidents. However, the existing research about hazardous chemical domino accidents only focuses on the pre-rescue stage and ignores the simulation of rescue-induced accidents that occur after rescue. Aiming at the problem, a quantitative representation algorithm for the spatial correlation of hazardous chemicals is first proposed to enhance the understanding of their spatial relationships. Subsequently, a graph neural network is introduced to simulate the evolution process of hazardous chemical cascade accidents. By aggregating the physical and chemical characteristics, the initial accident information of nodes, and bi-temporal node status information, deep learning models have gained the ability to accurately predict node states, thereby improving the intelligent simulation of hazardous chemical accidents. The experimental results validated the effectiveness of the method.

EFFICIENCY OF USING PORTABLE FIRE EXTINGUISHERS WHEN EXTINGUISHING LITHIUM-ION BATTERIES

The article substantiates the trends in using electric energy storage systems consisting of a battery, an inverter, connecting conductors, safety automation, and, if necessary, solar panels. Such systems typically use lithium-ion batteries because of several technical advantages: high specific energy capacity, high discharge-charging currents, and many charge-discharge cycles, i.e., longevity. The chemical and electrochemical reactions that occur during the charge-discharge cycles of lithium-ion batteries can lead to irreversible electrothermal processes. Such processes cause an uncontrolled increase in temperature, the release of hazardous gases, fires, and explosions, often accompanied by fire. Therefore, the authors conducted a successful full-scale field study of the effect of various extinguishing agents of the most common portable fire extinguishers in Ukraine on the efficiency of extinguishing lithium-ion batteries. Based on the experiment, we found that extinguishing the lithium-ion module using a portable carbon dioxide fire extinguisher is the least effective among the extinguishers studied, with the resumption of flame combustion occurring within 3–4 s after the cessation of carbon dioxide supply to the combustion centre. When using a portable powder fire extinguisher, the flame combustion of the test module resumed after 18–20 s. The desired extinguishing effect was achieved using low-density air-mechanical foam from the VVK-5 fire extinguisher and sprayed water with salt additives from a water extinguisher. Based on the obtained research results, we proposed recommendations for the selection of standards for the availability and use of portable fire extinguishers for the effective extinguishing of lithium-ion batteries at the rate of at least 5 kg of charge of working solution or water with salt additives per 5 kWh of energy capacity of a lithium-ion battery. Further research will identify influence patterns of the intensity of extinguishing agent supply on the efficiency of extinguishing lithium-ion batteries. Keywords: lithium-ion battery, fire, irreversible electrothermal process, fire safety.

DEVELOPMENT OF A TEST SAMPLE OF A SYSTEM FOR GENERATING AND SUPPLYING COMPRESSED AIR FOAM

An effective fire extinguishing agent for class A fires is the compressed air foam formed in Compressed Air Foam Systems (СAFS). Such systems have become widespread in leading countries such as the USA, Germany, China, and others. It is worth noting that the technical parameters of CAFS (intensity and consumption of an aqueous solution of foaming agent/air), implemented in the practice of fire extinguishing in the form of industrial samples, are designed and manufactured in such a way as to ensure effective extinguishing of developed fires of a significant area. When using existing samples for obtaining compression foam, a problem arises, which lies in the limited possibilities of regulating the supply of compression foam (intensity and consumption of the aqueous solution of the foaming agent/air), under which it is possible to use it with modified additives when extinguishing laboratory fires of solid combustible materials, and the lack of a smooth regulation of its supply. As a result of the research, the authors proposed a compressed air foam system to study its properties with the content of modified additives when changing the composition of the liquid and air that make it up. The manufactured system has the following parameters: multiplicity of 4–20, working pressure of systems of 4–8 bar, smooth adjustment of the consumption of aqueous solution/foaming agent of 2–20 l/min, and smooth adjustment of gas fraction consumption of 8–450 l/min. In particular, it is possible to adjust the consumption of the aqueous solution of the foaming agent and air, to work in dependant and autonomous mode, to regulate the intensity of the foam supply using nozzles of different diameters, and to change the porosity of the porous body in the foam generator. Further, we developed a system for measuring the flow of aqueous solution and air, which is a hardware and software complex. The system allows saving the measurement results to a PC in the form of an Excel spreadsheet for further development of dependencies and simultaneously displaying the flow rate of the aqueous foaming agent solution and air on the display screen and PC in real-time. Keywords: compressed air foam, class A fires, compressed air foam systems, modified additives.

Study on Understanding the Use of Light Fire Extinguishers in Airport Terminals

Emergencies and conditions can occur at any time. Preventive measures are necessary to reduce accidents and emergencies. This research, which measures the level of understanding of tenant employees regarding the use of light fire extinguishers in airport terminals, is of significant importance. The study used a mixed methods research approach with a sample of 77 people and obtained measurable values for tenant employees' understanding of light fire extinguishers. The results included 87% of tenant employees understanding emergencies, 81.8% knowing the meaning of light fire extinguishers, 55.8% knowing how to use light fire extinguishers, 58.4% who have never participated in socialization on light fire extinguishers use, and 83.1% who did not have a certificate/license for using light fire extinguishers, provide a crucial basis for further policy-making. In the form of preventive actions, these policies will be carried out by aircraft rescue and fire fighting in the form of fire prevention outreach/training through educational innovations in using light fire extinguishers via videos accessed by all tenant employees. The success of these actions will be measured through pre/post-test results before and after the material intervention, with certificates issued to participants who meet the assessment scoring. As part of the airport community, active participation in these initiatives is not just crucial but also a responsibility and a testament to the ownership of the safety of all airport users.

Review of Modern Forest Fire Detection Techniques: Innovations in Image Processing and Deep Learning

Fire detection and extinguishing systems are critical for safeguarding lives and minimizing property damage. These systems are especially vital in combating forest fires. In recent years, several forest fires have set records for their size, duration, and level of destruction. Traditional fire detection methods, such as smoke and heat sensors, have limitations, prompting the development of innovative approaches using advanced technologies. Utilizing image processing, computer vision, and deep learning algorithms, we can now detect fires with exceptional accuracy and respond promptly to mitigate their impact. In this article, we conduct a comprehensive review of articles from 2013 to 2023, exploring how these technologies are applied in fire detection and extinguishing. We delve into modern techniques enabling real-time analysis of the visual data captured by cameras or satellites, facilitating the detection of smoke, flames, and other fire-related cues. Furthermore, we explore the utilization of deep learning and machine learning in training intelligent algorithms to recognize fire patterns and features. Through a comprehensive examination of current research and development, this review aims to provide insights into the potential and future directions of fire detection and extinguishing using image processing, computer vision, and deep learning.

A new experimental method to study the flame inhibition performance of low concentration halogenated gas

The minimum fire extinguishing concentration is a key index for the development of next generation chemical clean fire extinguishing gases, which is usually got by the cup-burner. The fire suppression performance of low concentration of chemical gas is hard to be understood by the available methods. In this work, the fundamental acknowledgement of steady flame surface attacking mechanism by halon functional group is newly discussed by conducting a series of bench scale tests with a cylindrical channel under a varied fluorinated gases. The characteristics of flame propagation under differentiated air atmosphere environmental conditions is obtained. The influence of fluorine-containing gas flow rate on flame propagation speed is clarified. A dimensionless relationship including atomic radius, bond length, polarization degree, molar mass and molar volume are proposed to describe the influence of low concentration of fluorine-containing gas on flame propagation speed. It provides an insight for the understanding of the flame inhibition performance of low concentration halogenated gas.

Design Verification and Performance Testing of Container Valves for Offshore 30Mpa IG541 Fire Extinguishing System

Abstract Addressing the challenges of large space occupation, limited transmission distance, and suboptimal fire extinguishing efficiency of the current 15Mpa IG541 gas fire extinguishing system commonly found on offshore oil production platforms and ships, especially in deepwater facilities where stringent requirements exist for both transmission distance and environmental performance. Increasing the storage pressure can enhance space efficiency and extend the transmission range of the extinguishing medium. However, the core component, the container valve of the 30Mpa IG541 system, has faced foreign bottlenecks in terms of availability and technology transfer. To address this situation, a domestically developed and independently intellectual property-protected 30Mpa IG541 container valve has been designed and tested. This design encompasses material selection, flow area calculations, action mechanism design, sampling port design, inlet and outlet thread selection, safety diaphragm design, and thread strength calculations. Subsequent testing confirmed its suitability, including functional testing, sealing tests, hydrostatic pressure testing, blast performance testing, and salt spray testing. The valve passed all tests with flying colors, ensuring reliable opening under 135MPa pressure. The container valve has also been successfully certified by DNV. This achievement lays the foundation for the next phase of certification by a classification society and the broader application of this 30Mpa IG541 system in offshore engineering.

Maltose-based pyrotechnic aerosol forming composites for fire extinguishing application

This study explores the development of environmentally friendly aerosol forming composites (AFCs) for use in condensed aerosol-based fire extinguishing systems (CAFES). Traditional fire suppressants often pose environmental hazards; thus, a novel approach using maltose as a combustible binder combined with potassium nitrate as an oxidant was examined. To modify the burn rate and improve combustion efficiency, calcium carbonate (CaCO3) and iron (III) oxide (Fe2O3) were incorporated as burn rate modifiers. AFCs demonstrated high combustion efficiencies (≥ 95%) and variable burn rates (3.3–13.8 mm/s). The fire extinguishing concentration of AFC was found ≤ 53 g/m3. Comprehensive analyses including thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction, and Fourier transform infrared spectroscopy (FTIR) confirmed the formation of potassium carbonate, potassium bicarbonate, and potassium hydroxide in aerosols. Aerosol distribution within the fire test chamber was homogeneous, as evidenced by pH measurements at various locations. These findings suggest that maltose-based AFCs are promising candidates for the development of eco-friendly fire extinguishing systems.

분전반, 배전반 등에 사용하는 질산칼륨 기반의 소공간 소화장치의 성능에 관한 기초 연구 - 소화메커니즘 및 A급 소화성능을 중심으로

As there was no objective date on the fire extinguishing mechanism and performance of potassium nitrate-based small space fire extinguisher that can automatically extinguish fires in small spaces (less than 0.36 ㎡) such as distribution boards and distribution boards, we attemped to conduct basic research on this. We sought to confirm the importance of fires in switchboards and other devices through fire statistical analysis of electrical factors, and analyzed fire extinguishing mechanisms that react with heat based on potassium nitrate. We also sought to determine the interconnectivity of related variables through Class A fire extinguishing tests. Through analysis of fire statistics, the importance of electrical fires was confirmed and the cause of fire in the switchboard was investigated. By investigating its composition, it was found that it was a safe material that could be used for fire extinguishing, and that in the event of a fire, the thermal decomposition of KNO3 produced condensed aerosol particles, K2CO3, which could extinguish the fire. Through the Class A fire extinguishing test of the switchboard, it was confirmed that the fire could be reliably extinguished. The following conclusions were drawn through this study. 1. Analysis of fire statistics confirmed that electrical factors were the biggest cause of fire and that fires caused among this short circuit and insulation deterioration were the main causes. 2. The fire risk of switchboards, distribution boards, etc. was confirmed, and it was found that it was necessary to install simple fire extinguishers for small spaces that can quickly respond to and extinguish fires. 3. The fire extinguishing mechanism of potassium nitrate was confirmed to extinguish the fire by generating condensed aerosol particles, K2CO3, through thermal decomposition of KNO3 when a fire occurs. 4. Through the Class A fire extinguishing performance test, it was confirmed that there was a relationship between fire extinguishing delay time, weight, and volume, and the relationship could be expressed as , and it was found that a value of 1 or more is required for fire extinguishing.

CHSE Readiness in the New Normal Era (Case Study: Airbnb Owners in Denpasar City, Bali)

This research examines Airbnb listings’ readiness to fulfils CHSE in Denpasar City. This result shows three priority amenities: a fire extinguisher, a first aid kit, and a smoke detector. However, the readiness of Airbnb to meet CHSE requirements remains limited and only found in certain types of listing. The study provide important insights into the lack of CHSE implementation among Airbnb listings, mainly in private and hotel room listings. This problem is further exacerbated by the difficulty of supervising the implementation of the CHSE, as Airbnb’s legal status remains debatable following hosts’ willingness to register with the Tourism Office.

Numerical Simulation of Evaporative Gas Behavior Inside Fuel Tank During Fire Extinguishing Process

Numerical Simulation of Evaporative Gas Behavior Inside Fuel Tank During Fire Extinguishing Process

Influence of modified additives on the properties of compressed air foam

The object of this study is the properties of compressed air foam with the use of modified additives: its drainage time and expansion ratio. The main properties of compressed air foam that affect the effectiveness of fire extinguishing are its drainage time and expansion ratio. At the same time, a number of authors have confirmed that the introduction of chemically modified additives into the composition of water fire extinguishing substances makes it possible to increase the effectiveness of fire extinguishing. The problem to be solved was to determine the influence of five modified additives (NH4)2HPO4, NH4H2PO4, (NH4)2СO3, K2CO3 and KCl in the concentration range of 1–5 % by mass on the expansion ratio and drainage time of the compressed air foam. The results showed that the content of additives (NH4)2HPO4, NH4H2PO4 and (NH4)2СO3 in the aqueous solution of the foaming agent does not affect its expansion ratio within the given limits. On the other hand, with K2CO3 and KCl additives, it was not possible to obtain compressed air foam with a expansion ratio of 5–20, that is, their inefficiency in compressed air foam was noted. The characteristic dependence of the effect of (NH4)2HPO4, NH4H2PO4 and (NH4)2СO3 additives on drainage time has been determined. The greatest drainage time is characteristic of the K≈20 generation mode. The highest recorded drainage time index was established for NH4H2PO4, namely 5.45 min; for (NH4)2HPO4 the drainage time was lower by 8 %; for (NH4)2СO3 the drainage time was lower by 20 %. At the same time, with the use of (NH4)2HPO4, NH4H2PO4 and (NH4)2СO3, it is characteristic to obtain a foam with lower drainage time compared to foam of a conventional composition. Thus, for foam with a expansion ratio of K≈20, the drainage time of foam with NH4H2PO4 is lower by 17 %, with (NH4)2HPO4 by 23 %, and with (NH4)2СO3 by 33 %. The effect of reducing the drainage time of the foam can have a decisive role in reducing its effectiveness when used for extinguishing flammable liquids due to the extinguishing mechanism but is not decisive for extinguishing solid substances. Therefore, the fire-extinguishing effectiveness of compressed air foam with modified additives during the extinguishing of solid combustible materials in comparison with the conventional CAF composition requires further study

Gas Fire Coupling Control of Goaf Based on Numerical Simulation

ABSTRACT In response to the problem that traditional gas control methods such as water injection and inert gas fire extinguishing are not effective and have a high level of risk in goaf, this study uses COMSOL software to establish a three-dimensional numerical simulation model of goaf, and combines air leakage intensity, oxygen concentration, and floating coal thickness to calculate the gas fire hazard area, in order to achieve effective control. The results show that the deviation between the data obtained from the numerical simulation and the actual measurement value is about 7 m, which proves that the given solution is reliable. The gas concentration of the wind lane and the upper corner is controlled below 1%, which proves that this method ensures the safety of the working environment. The above results show that the design method realizes the effective control of gas fire in the goaf, and provides reference for mine safety management and gas disaster control.

Understanding fire combustion characteristics and available safe egress time in underground metro trains: A simulation approach

Due to insufficient oxygen supply in the tunnel, incomplete combustion of the underground metro train fire easily produces toxic gases and smoke dust, causing difficulty in breathing for passengers and rescue. The experimental study of the fire combustion characteristics of metro trains in the tunnel is of great significance for designing metro fire extinguishing and fire prevention systems and providing reliable guidance for emergency evacuation in fire scenarios. A train fire model is established to study the effects of various factors on fire combustion characteristics and calculate the available safe egress time (ASET). The smoke spread characteristics under different conditions such as fire source power, fire source location, carriage layout, and train location are simulated. The simulation results show that the fire source power, location, and seat arrangement have a significant impact on the smoke spread characteristics of carriage fires and ASET.

Performance analysis of fire protective clothing: a review

Firefighters in such serious environments (i.e., hazardous flames and radiant heat, high air temperatures, hot chemicals and liquids) must wear fire protective clothing during fire extinguishing and rescue operations. Many studies in the field of fire protective clothing have been conducted to evaluate the protective, mechanical and comfort performance of fire protective clothing. A comprehensive review of the literature has been undertaken to provide a better understanding of single-layer and multilayer fire protective clothing with protective, mechanical and comfort performance. Factors affecting the durability of protective clothing in the light of their expected retirement age and a number of significant standards for laboratory and manikin testing are discussed. The comfort of wearing clothing is another aspect that needs special consideration when designing a multilayered fire protective suit. A number of emerging technologies have been outlined to address the various challenges of the present day.

Preparation of fully physically crosslinked double-network gel and its fire prevention mechanism

It is important to gain an in-depth understanding of the structure of fire prevention and extinguishing materials during self-heating of coal. In this paper, an Al3+-CMC/PAM-MMT fire prevention and extinguishing gel with double-network was prepared using sodium carboxymethyl cellulose (CMC) and polyacrylamide (PAM) as raw materials, and aluminum citrate (AlCit) and sodium montmorillonite (Na-MMT) as auxiliary materials, by introducing the fully physically crosslinking effect. The optimal amounts of CMC, PAM, AlCit and MMT were determined to be 2 %, 3 %, 8 %, and 3 %, respectively, based on gelation time, stability, and resistance of the gel. The micromorphological image of the double-network gel exhibited a laminar structure of parallel-aligned fibrous networks, where the pores and channels exhibited more complex shapes and became smaller in size, highlighting the superiority of the double-network architecture. The rheological tests showed that the double-network gel had superior structural stability and viscosity under varying shear rates, making it more effective in covering the fire source, enhancing extinguishing efficiency. Additionally, its higher storage and loss moduli indicated stronger elasticity and mechanical properties compared to the single-network gel, emphasizing its advantages in energy storage and recovery. The characterization of active functional groups showed that there was an effective suppression of reactions involving hydroxyl, hydrocarbon, and carbonyl functional groups, during the spontaneous combustion process of coal, following treatment with the gel. Additionally, a proposed mechanism for the gel formation was presented. In the sealing performance test, the pressure-bearing capacity of the double-network gel was approximately twice that of the single-network gel. It indicated that the multi-level structure formed by the gel led to higher density of physical cross-linking points, which provided better sealing performance. Thermogravimetric analysis showed significant decrease in total calorific value and increase in activation energy of coal, after treatment with the gel, rendering it more difficult for spontaneous coal combustion. In the small-scale fire extinguishing performance test, the double network of Al3+-CMC/PAM-MMT gel demonstrated effective suppression of spontaneous combustion of coal and reduced the susceptibility to re-ignition. The fire prevention mechanism of the gel was further explored experimentally.