Methodology for mapping the probability of fire occurrence in the Brazilian cerrado biome based on the danger of fire propagation variables

The area covered by the Brazilian cerrado biome has been greatly reduced in recent years due to the expansion of agricultural land and the increased number of fire outbreaks. The objective of this paper is to propose a methodology based on geospatial analysis and logistic regression analysis (LRA) for mapping the probability of fire occurrence in Brazilian cerrado conservation units. This model was applied in the Serra da Canastra National Park (SCNP) in the Southeast of Brazil. The methodology uses the maps of the following environmental variables, which are related to the danger of fire propagation: wind effect (WIN), terrain convexity (CVX), slope (SLO), drainage density (DRD), altitude (ELV), vegetation index (NDVI), and road density (ROD). The results of the LRA showed that the variables SLO, ELV, NDVI, ROD (p<0.0001), DRD (p=0.0005) and WIN (p=0.0007) contributed significantly to the occurrence of fire outbreaks. The model correctly classified 94.26% of cases. We conclude that this methodology can be used to inform the planning of firefighting actions in the Brazilian cerrado biome.

Simulation of Wood Combustion in PATO Using a Detailed Pyrolysis Model Coupled to fireFoam

The numerical simulation of fire propagation requires capturing the coupling between wood pyrolysis, which leads to the production of various gaseous species, and the combustion of these species in the flame, which produces the energy that sustains the pyrolysis process. Experimental and numerical works of the fire community are targeted towards improving the description of the pyrolysis process to better predict the rate of production and the chemical nature of the pyrolysis gases. We know that wood pyrolysis leads to the production of a large variety of chemical species: water, methane, propane, carbon monoxide and dioxide, phenol, cresol, hydrogen, etc. With the idea of being able to capitalize on such developments to study more accurately the physics of fire propagation, we have developed a numerical framework that couples a detailed three-dimensional pyrolysis model and fireFoam. In this article, we illustrate the capability of the simulation tool by treating the combustion of a wood log. Wood is considered to be composed of three phases (cellulose, hemicellulose and lignin), each undergoing parallel degradation processes leading to the production of methane and hydrogen. We chose to simplify the gas mixture for this first proof of concept of the coupling of a multi-species pyrolysis process and a flame. In the flame, we consider two separate finite-rate combustion reactions for methane and hydrogen. The flame evolves during the simulation according to the concentration of the two gaseous species produced from the material. It appears that introducing different pyrolysis species impacts the temperature and behavior of the flame.

Study on Gas-Generating Property of Lithium-Ion Batteries

A main cause of fires and explosions in lithium-ion batteries is the generation of combustible gases by them, and when a large number of batteries are densely packed, like in an Energy Storage System, there is a high risk of thermal runaway and fire propagation. Currently, many studies are being conducted worldwide to predict and prevent the generation of combustible gases, and thermal runaway in lithium-ion batteries, but they are still in progress. Therefore, in this study, we analyzed the gases generated before and after thermal runaway in lithium ion batteries, to prepare a basis for reducing the risk of thermal runaway. We aimed to establish the basis for prevention by early detection in the event of thermal runaway, by understanding the type and characteristics of the generated gases. For the experiment, lithium ion batteries were classified in terms of appearance (cylindrical, prismatic, pouch type), and cathode materials (NCM, NCA, LFP). The gases generated was measured against time. An FT-IR analyzer was used for gas measurement, and a separate hydrogen sensor was installed in the chamber to analyze changes in the types of gas, and measure the mass of the lithium ion battery over time. In the experiment, CO2 and CO were generated the most during thermal runaway in all lithium-ion batteries. Thereafter, CO2 increased, and CO decreased in the prismatic and pouch types, and both CO2 and CO increased in the cylindrical type. HF (a toxic gas), and H2 having a wide explosive range, were also generated, and the concentrations of these gases were inversely proportional to each other.

Battery Train Fire Risk on a Steel Warehouse Structure

Lithium ion battery fire hazard has been well-documented in a variety of applications. Recently, battery train technology has been introduced as a clean energy concept for railway. In the case of heavy locomotives such as trains, the massive collection of battery stacks required to meet energy demands may pose a significant hazard. The objective of this paper is to review the risk evaluation processes for train fires and investigate the propagation of lithium ion battery fire to a neighboring steel warehouse structure at a rail repair shop through a case study. The methodology of the analyses conducted include a Monte Carlo-based dynamic modeling of fire propagation potentials, an expert-based fire impact analysis, and a finite element (FE) nonlinear fire analysis on the structural frame. The case study is presented as a demonstration of a holistic fire risk analysis for the lithium ion battery fire and results indicate that significant battery fire mitigations strategies should be considered.

RESEARCH OF THE INFLUENCE OF EXTERNAL VERTICAL ENVIRONMENTAL STRUCTURES ON THE SPREAD OF FIRE ON THE SURFACE OF WALLS

Purpose. Using FDS modelling to investigate the influence of external vertical enclosing structures on the spread of fire on the surface of external wall structures with facade insulation with combustible insulation.Methods. Using the software package Pyrosim performed тumerical modelling of the dynamics of development and spread of fire on the surface of the thermal insulation and finishing system, which serves as a user shell for the program Fire Dynamics Simulator (FDS). To visualize the results of calculations, the software module of the PyroSim Smoke view system was used, which allows building appropriate graphical representations of temperature distributions. This system also allows you to monitor the dynamics of temperature fields and reproduce the heating process with animation.Results. With the help of computer modelling of fire test parameters of facade insulation system for fire propagation in FDS environment, numerical and graphical indicators were obtained by computer simulation of the fire test parameters of the facade insulation system for fire propagation in the FDS environment. They characterize the process of occurrence, spread and development of fire by the surface of the facade insulation system. Also, we established the influence of external vertical enclosing designs on a fire surface of outside walls with a warming of a facade by a combustible heater. The obtained results of numerical modelling of the parameters of the fire test of the facade insulation system for the propagation of fire in the FDS environment indicate that the overall standard deviation in the theoretical data was higher than the results of experimental stud-ies. Thus, the presence in the structure of a fragment of the building vertical wall (inner corners of the building) creates a “shielding effect”, i.e. the flame emanating from the window is reflected and the temperature on the surface of external walls with facade insulation rises significantly. Thus, for thermocouples T15-T17 the temperature rises by 140-220 °C; for thermo-couples T19-T21 – by 180-350 °C; for thermocouples T27-T29 – by 110-190 °C, respectively.In addition, the presence of external vertical enclosing structures on the facade of the building contributes to the increase in temperature and inside the structures of external walls with facade insulation, as evidenced by the readings of thermocouples T33 and T35 – an increase of 50-100 °C; thermocouples T36 and T38 – increase by 50-180 °C.Practical value. The results of numerical simulations obtained by the author are aimed at the use of design organizations in the installation of fire belts using noncombustible mineral wool boards in the inner corners of the building as insulation in the presence of window and balcony openings to prevent fire from spreading on facade systems in residential buildings.

Combustibility of fuel material for forest species

The work aimed to characterize the flammability of different forest species. The combustible materials were collected in two places with different phytophysiognomies, both in the state of Paraíba, Brazil. The plant materials used were: Poincianella bracteosa, Aspidosperma pyrifolium, Luetzelburgia auriculata, Croton sonderianus and Pinus sp. acicles and branches were used as a control. The burns were carried out in an open area located in the forest nursery, where approximately 0.5 kg of material was weighed on a precision scale. After the organization of the plots, the thickness of each pile was measured with the aid of a ruler graduated in centimeters. To determine the speed of fire propagation, the average time spent by the fire front (m s-1) to travel pre-established distances during the fires was measured. It is observed that among the studied materials, Pinus was the one that presented the lowest weight after burning the material and was the species that presented the highest temperature after burning, followed by C. sonderianus and A. pyrifolium. Before burning, all species showed behaviors, ranging from 30 to 33 °C. It is extremely important to replicate this type of study in forest areas, since the variations found can influence the results. The effect of burning combustible materials on soil temperature was greater in treatments with Pinus and C. sonderianus.

Fire dynamics in the attics

Произведена экспериментальная оценка развития пожаров в объеме чердачных помещений в зависимости от типа кровельного покрытия. По результатам исследования отмечается, что применение кровли из горючих материалов способствует более быстрому образованию сквозных прогаров и выходу пламени за пределы помещения, в то время как в случае использования сплошных настилов из негорючих материалов горение в течение длительного времени развивается в объеме, а после появления общей вспышки быстро распространяется от очага в объеме. Представлены рекомендации по осуществлению мероприятий в области обеспечения требований Федерального закона в части ограничений последствий пожара. The article presents the results of an experimental assessment of fire development dynamics in the volume of attics, depending on the type of roofing. According to the results of the study, it is noted that the use of a roof made of combustible materials contributes to the faster formation of through burnouts and the exit of the flame outside the room, when solid decking made of non-combustible materials is used, fire develops for a long time in the volume, and after the formation of a general flash it quickly spreads from the hearth all over the volume. Open fire time over a roof made of combustible materials is more than twice less than when testing a roof with a solid flooring made of non-combustible materials and makes 5.5 minutes, compared to 13.5 minutes. In a real fire with a large amount of fire load in the volume of the attic the temporary gap may be sufficient to ensure that the fire, in the absence or failure of the fire detection system, covers the entire construction volume before it is detected by random witnesses and information about it is received by the fire department. When using a roof system made of combustible materials, it is noted that despite the high rate of initial fire development, the dynamics of subsequent fire propagation in the roof volume is lower, even in the absence of fire-resistant treatment of wooden structures. Based on the results of the study there are presented recommendations for the implementation of measures to meet the requirements of the Federal Law No. 123-FZ dated 22.07.2008 “Technical Regulations on Fire safety requirements” in terms of limiting the fire consequences.