Fire Area Research Articles

Guldborgsund Arson House Fire Experiment and Numerical Investigation

AbstractThis paper describes the Guldborgsund arson house fire experiment performed in Denmark and the subsequent numerical investigation. Gas temperatures were measured with four thermocouple trees, and smoke detector activation times were recorded in all rooms. A two-step approach was used to perform the numerical modelling for reproduction of the fire scene. The measured temperatures in the room of fire origin were used as an input for back calculating the Heat Release Rate (HRR) with the two-zone model Argos. As a next step, this HRR was used in the Fire Dynamic Simulator (FDS) to predict the temperatures and the smoke detectors’ activation times in other rooms. The FDS model was partly build using output files from the laser scanning. A sensitivity analysis is presented, where the effect of nine input parameters was investigated, including HRR, the material properties, the height of the fuel bed, the fire area, level of geometrical detail of the first item ignited etc. This study showed that the measured soot deposition heights on the walls differed from the heights of measured sharp temperature gradients used to indicate the hot smoke layer. The numerical simulations resulted in less than 50% error for most of the temperature measurement points during the fuel-controlled stage of the fire and results were the most sensitive to the input HRR. Material properties in FDS had a significant influence on the computed upper-layer gas temperatures at late stages of the fire.

Fire behavior simulation of Xintian forest fire in 2022 using WRF-fire model

IntroductionThe behavior of forest fire is a complex phenomenon, and accurate simulation of forest fire is conducive to emergency response management after ignition. In order to further understand the characteristics of forest fire spread and the applicability of WRF-Fire in China, which is a coupled fire-atmospheric wildfire model, this study simulated a high-intensity forest fire event that occurred on October 17, 2022 in Xintian County, southern Hunan Province.MethodsBased on the fire-atmosphere coupled WRF-Fire model, we used high-resolution geographic information, meteorological observation and fuel classification data to analyze the forest fire behavior. At the same time, the simulation results are compared with the fire burned area observed by satellite remote sensing forest fire monitoring data.ResultsThe study found that, the simulated wind speed, direction and temperature trends are similar to the observation results, but the simulated wind speed is overestimated, the dominant wind direction is N, and the temperature is slightly underestimated. The simulated wind field is close to the actual wind field, and the simulation results can show the spatial and temporal variation characteristics of the local wind field under complex terrain while obtaining the high-resolution wind field. The simulated fire burned area is generally overestimated, spreading to the north and southwest compared with the observed fires, but it can also capture the overall shape and spread trend of the fire well.DiscussionThe results show that the model can accurately reproduce the real spread of fire, and it is more helpful to forest fire management.

Landcover-categorized fires respond distinctly to precipitation anomalies in the South-Central United States

Satellite detection of active fires has contributed to advance our understanding of fire ecology, fire and climate dynamics, fire emissions, and how to better manage the use of fires as a tool. In this study, we use active fire data of 12 years (2012–2023) combined with landcover information in the South-Central United States to derive a monthly, open-access dataset of categorized fires. This is done by calculating a fire predominance index used to rank fire-prone landcovers, which are then grouped into four main landscapes: grassland, forest, wildland, and crop fires. County-level aggregated analyses reveal spatial distributions, climatologies, and peak fire months that are particular to each fire type. Using the Standardized Precipitation Index (SPI), it was found that during the climatological fire peak-month, the SPI and fires exhibit an inverse relationship in forests and crops, whereas grassland and wildland fires show less consistent inverse or even direct relationship with the SPI. This varied behavior is discussed in the context of landscapes’ responses to anomalies in precipitation and fire management practices, such as prescribed fires and crop residue burning. In a case study of Osage County (OK), we find that large wildfires, known to be closely related to climate anomalies, occur where forest fires are located in the county and absent in areas of grassland fires. Weaker grassland fire response to precipitation anomalies can be attributed to the use of prescribed burning, which is normally planned under environmental conditions that facilitate control and thus avoided during droughts. Crop fires, on the other hand, are set to efficiently burn residue and are practiced more intensely in drier years than in wetter years, explaining the consistently strong inverse correlation between fires and precipitation anomalies. In our increasingly volatile climate, understanding how fires, vegetation, and precipitation interact has become imperative to prevent hazardous fire conflagrations and to better manage ecosystems.

A preliminary study of combustion flame by digital image processing and residue for fireworks flash powder

Fireworks play a vital role in festive celebrations and entertainment. These fireworks industries are administered by the Petroleum and Explosives Safety Organisation (PESO), Nagpur, Government of India. Even though PESO prescribed the standard composition for various fireworks products, concerns persist regarding the potential deviation from these standards, particularly in the pursuit of increased noise levels to attract consumers. This change in the burning and reactive properties of chemicals could potentially lead to accidents and environmental pollution. The current work investigated the combustion characteristics of two unknown market flash powder samples and a PESO standard sample. The samples were openly ignited in a controlled atmosphere, and video recordings of the resulting chemical flames were analyzed to determine fire area, flame intensity, and motion magnitude. The residues were also collected for EDAX and SEM analysis. Fire pixels from video frames are segmented to create a comprehensive database detailing flame area and motion magnitude under different circumstances. From the flame area profile, motion magnitude and SEM/EDAX analysis, it is found that PESO standard sample combustion is better than the unknown flash powder combustion.

Development of an Algorithm for Assessing the Scope of Large Forest Fire Using VIIRS-Based Data and Machine Learning

Forest fires pose a multifaceted threat, encompassing human lives and property loss, forest resource destruction, and toxic gas release. This crucial disaster’s global occurrence and impact have risen in recent years, primarily driven by climate change. Hence, the scope and frequency of forest fires must be collected to establish disaster prevention policies and conduct relevant research projects. However, some countries do not share details, including the location of forest fires, which can make research problematic when it is necessary to know the exact location or shape of a forest fire. This non-disclosure warrants remote surveys of forest fire sites using satellites, which sidestep national information disclosure policies. Meanwhile, original data from satellites have a great advantage in terms of data acquisition in that they are independent of national information disclosure policies, making them the most effective method that can be used for environmental monitoring and disaster monitoring. The Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the Suomi National Polar-Orbiting Partnership (NPP) satellite has worldwide coverage at a daily temporal resolution and spatial resolution of 375 m. It is widely used for detecting hotspots worldwide, enabling the recognition of forest fires and affected areas. However, information collection on affected regions and durations based on raw data necessitates identifying and filtering hotspots caused by industrial activities. Therefore, this study used VIIRS hotspot data collected over long periods and the Spatio-Temporal Density-Based Spatial Clustering of Applications with Noise (ST-DBSCAN) algorithm to develop ST-MASK, which masks said hotspots. By targeting the concentrated and fixed nature of these hotspots, ST-MASK is developed and used to distinguish forest fires from other hotspots, even in mountainous areas, and through an outlier detection algorithm, it generates identified forest fire areas, which will ultimately allow for the creation of a global forest fire watch system.

Применение методов пространственного анализа при оценке степени горимости лесов Хабаровского края

Forest fires are the dominant factor in the transformation of natural landscapes in the boreal zone. The area of the Khabarovsk Territory, 93.6 % of which belongs to the forest fund lands, currently has a forest cover of only 66.5 %, which is largely due to forest fires. This makes urgent the problem of reducing the forest fire frequency in the region, including in terms of assessing the actual fire frequency for predicting the risks of landscape fires. The article shows the possibilities of using spatial analysis methods of the Spatial Analyst module of the ArcGIS 10.8 software package to assess the degree of actual forest fire frequency based on calculating the number of fires per 1 million and 250 thousand ha and the area of fires per 1000 ha for a sliding window of a given size. Based on the data from the Remote Monitoring Information System of the Federal Forestry Agency for 2000–2020 and the data on the number of fires from the Fire Information for Resource Management System website for 2000–2021, an assessment of the actual fire frequency for the Khabarovsk Territory has been carried out. The analysis of the results reflects the high spatial and seasonal heterogeneity of the spread of landscape fires in the territory and their proximity to transport and residential structures. Areas with high fire frequency often do not coincide with the boundaries of forestry enterprises, and the maximum indicators are typical for non-forest areas that are not covered by forestry statistics. For different seasons of the year, along with quantitative differences, spatial shifts of firing points and areas with their high density are also observed. Most of the lands in the region (88.3 %) in terms of fire danger belong to the “low” and “below medium” fire frequency categories, which is primarily due to the low degree of development of these areas. The assessment of the degree of fire frequency in the territory on the basis of annual and seasonal maps of the density of firing points, calculated using the sliding window method, makes it possible to fairly objectively and in detail reflect the average long-term risk of fire occurence outside of reference to forestry boundaries. In combination with a map of the distribution of forests by natural fire hazard classes based on pyrological characteristics, the results of the reseаrch can become the basis for calculating the background fire risk, reflecting the risk of fire occurrence and development.

Study on Fire Smoke Movement Characteristics and Their Impact on Personal Evacuation in Curved Highway Tunnels

In the existing research on tunnel fires, researchers primarily focus on straight tunnels, neglecting the impact of curved sidewalls in curved tunnels. Based on the theory of smoke diffusion, a series of CFD numerical simulations was conducted using the Fire Dynamics Simulator to investigate the characteristics of smoke distribution in a curved highway tunnel. The results indicated that distinct smoke distribution characteristics were observed when a fire occurred in a curved tunnel compared with those observed in straight tunnels, with significant differences particularly evident for the radius of curvature of the tunnel below 1000 m. By comparing the smoke distribution characteristics from various fire source locations, the most unfavorable fire source locations within a curved tunnel were determined. High-temperature fire smoke bounds between the inner and outer walls of the tunnel, leading to the formation of multiple high-temperature zones in proximity to the fire source, rather than diffusing directly towards the exit in a linear tunnel. Additionally, based on an analysis of temperature, visibility, and CO concentration at characteristic heights, suitable locations for pedestrian crossings within the tunnel were deduced and an evacuation strategy for persons within the core fire area was proposed. The results can provide a reference for personal evacuation strategies in curved highway tunnel fire scenarios and the design of an adit for people passing in such tunnels.

Investigating the Actuation of Sidewall Sprinkler in an Atrium Using CFD Simulation

This study investigates the actuation of sidewall sprinklers in large-scale buildings with high-ceilinged atriums, addressing the challenges of unique architectural configurations. Compliance with NFPA 101 requires automatic sprinkler systems, including atrium areas, in these buildings. To maintain aesthetic considerations, design engineers, particularly in the middle east, often propose sidewall sprinklers as an alternative to traditional ceiling sprinklers. This research assesses whether the sidewall sprinklers would actuate during a fire using Fire Dynamic Simulator (FDS). The findings indicate that sidewall sprinklers will fail to actuate if the fire is located at the centre of the atrium, even if the edge of the fire area is below the sprinklers. Furthermore, the study emphasizes the importance of using an FDS mesh resolution (D*/dx) of 6 or finer resolution when measuring temperatures near the flame or fire plume to ensure accurate evaluations of sprinkler activation. These findings provide valuable insights for design engineers and authorities, assisting in decision-making processes related to fire safety measures, system designs, and regulatory compliance.

Écouter le feu. The aftermath of wildfires and the question of rebuilding in high risk fire areas

Mega-fires have become frequent in areas around the world. They are no longer limited to areas in the Mediterranean climate. Extreme fires are now burning in Canada and Siberia due to more frequent fire weather conditions. Such conditions are strongly linked to the warming of the earth's atmosphere. In the US the term mega-fires came into use after the 1988 fire at Yellowstone Park. Such fires can permanently transform a landscape into a non-forested habitat. Wildfires are uncontrolled fires that burn in the wildland urban interface. No longer are wildfires a topic of interest only to foresters. Those in the practice of urban design and planning need to take notice. Land-use changes made by local governments have permitted urban development within forested areas and they have further exacerbated fire risks.

Forest fires in Irkutsk region as a possible source of benz(a)pyrene in the atmosphere of Bratsk

The aim of the study is to analyze wildfires in Irkutsk region and its districts in 2014-2020 as a possible source of benz(a)pyrene pollution of the atmospheric air in Bratsk. The dynamics of the number, the area of fires and their dependence on each other is explored. A comparative assessment of fires in the Bratsk district, Bratsk and its surrounding districts, and in Irkutsk region was carried out. The dynamics of reducing atmospheric air pollution with benz(a)pyrene in Bratsk during the study and the level of average carcinogen content in the atmosphere of 16 cities of the region was explored. Positive trends and linear dependences of the average annual and maximum monthly concentrations of benz(a)pyrene in the atmospheric air of Bratsk on the indicators of wildfires in the Bratsk district, a group of districts and in the entire region were found. A regular increase in the accuracy of the correlation between the content of benzo(a)pyrene in the atmosphere of Bratsk and the indicators of fires in a number of territories from Irkutsk region to Bratsk district was shown. Higher correlation coefficients were found for indicators of average annual concentrations of benzo(a)pyrene and for the number of fires compared, respectively, with maximum average monthly concentrations and indicators of natural burned areas. The average concentration of benzo(a)pyrene in the atmosphere of 16 cities did not depend on the indicators of fires in Irkutsk region. A conclusion is made about possible consequences of wildfires for air pollution in Bratsk with carcinogenic benzo(a)pyrene.

Research on Resistance Characteristics of Fire Zone of Mine Tunnel Fire and Construction of Calculation Model

To investigate resistance change in the fire area of a roadway caused by roadway fires, a mathematical calculation model for thermal resistance is developed. Theoretical research is conducted to analyze the factors influencing resistance change through theoretical derivation, revealing that temperature is a key factor contributing to the change in thermal resistance. By leveraging the correlation between changes in CO concentration and temperature on the downwind side of the roadway within the fire zone, researchers developed mathematical models to predict temperature increases at various points downwind of the fire source. These models were then used to determine the mathematical relationship governing the change in thermal resistance. The accuracy of the numerical simulation software was validated using Fluent numerical simulation software and scaled-down model experiments. Full-scale numerical simulation experiments were conducted to investigate the fire characteristics of roadway fires and validate the thermal resistance mathematical model. The results indicate that the thermal resistance in the numerical simulation is 7.55 Pa at 20m from the fire source and 5.54 Pa at the end of the roadway. The decrease in resistance is linear. The minimum error between the thermal resistance calculated by the mathematical model and the gradient of the pressure drop in the numerical simulation is 0.03 Pa, approximately 2.3%. Furthermore, the fitting degree of the pressure drop in each section is as high as 97.7%. The calculation model demonstrates high accuracy and offers a theoretical foundation for investigating fire resistance in tunnel fire.

Collapse modes and mechanisms of planar multi-story large-span steel frames under fire

This paper investigates the collapse modes and mechanisms for planar multi-story large-span steel frames exposed to fire. Based on a systematic parametric analysis conducted with a wide range of parameters, including structural topological forms, fire scenarios, component sizes, load cases, fire protection levels, section temperature gradients, and wind loads. Eight potential collapse modes are identified: general inward collapse, rebalancing collapse, partial lateral collapse, heated large-span beam-induced inward collapse, restraint failure-induced collapse, overall downward collapse, unheated large-span beam-induced inward collapse, and overall lateral collapse. Simultaneously, by combining typical fire cases, corresponding structural collapse mechanisms are explored to reveal the differences in the failure sequence of locally heated components and the final structural collapse extent for different collapse modes. Furthermore, this study also analyzes the evolution laws of key horizontal and vertical displacements and velocities within the fire area for various modes, highlighting distinctions resulting from diverse collapse mechanisms. Finally, a detailed summary of various collapse modes is provided, involving reasons for inducing structural local collapse, the final extent of progressive collapse, possible areas of occurrence, and potential mode transitions as parameters change.

Research on early identification of burning status in a fire area in Xinjiang based on data-driven

The early combustion stage in coalfield fire areas (CFA) is the initial phase of coal fire development and spread, making the effective identification of the combustion state crucial. To effectively identify the early combustion state of CFA, this study investigates the CFA in Xinjiang, China. Based on the abnormal characteristics of shallow soil and surface space, a data-driven evaluation method for identifying early combustion states of CFA is proposed. Construct a soil-gas dual-layer early combustion state assessment model of CFA. The evaluation model was applied and validated in the coal fire areas of Xinjiang, China.The results show that there are obvious differences in the spatial distribution of auto-ignition gas, temperature, humidity, surface vegetation coverage and other indicators in the shallow soil and surface space of the coal fire area. The early combustion states of coal fires in areas A, B, and C in the survey area are all in the combustion stage, the combustion state in area D is in the oxidation stage. The accuracy of the evaluation method is bidirectionally verified by the radon measurement method and the infrared thermal imaging detection method. It provides a theoretical basis for controlling the development and spread of coalfield fire areas.

Simulation on the Dispersion of Natural Gas and its Volume Cloud Distribution on an Offshore Fixed Platform

The formation, migration and volume distribution of gas clouds, which are dominated by natural gas after oil and gas leakage, are the material basis of fire and explosion accidents on offshore platforms. Based on an offshore platform as the background, this paper conducts research on the gas cloud using numerical simulation method, the selection of different wind speeds, leak leakage rate of quality, wind direction and the direction angle, the leakage of gas diffusion behaviour simulation studies and its size distribution. There is a “coupling” effect on the volume value of 5% CH4 cloud between different wind speeds, leakage mass rates, and wind direction and leakage direction. When the wind speed is 13 m/s, the leakage mass velocity is 8 kg/s, and the included angle between wind direction and leakage direction is 180°, the “coupling” effect on the volume value of 5% CH4 cloud increases significantly. The above research results can provide a reference for the reasonable division of process risk area, firewall design and quantitative risk assessment of fire and explosion of an offshore platform.

The impacts of inter- and intra-seasonal burns on the terrestrial orchid Pterostylis curta

Prescribed burning is a management tool used for both management of fuel loads and for ecological purposes across fire prone areas. While in temperate areas wildfires usually occur during the hottest summer months, prescribed burns are generally conducted in autumn and spring, when conditions are more suitable for controlling fire. Orchids maintain avoidance mechanisms, such as persisting as dormant tubers during the predominant fire season, and therefore may be at risk from prescribed burns occurring during their active life cycle period. Using a glasshouse experiment, we investigated the impacts of fire season on the Australian orchid species Pterostylis curta. This approach allowed us to i) implement seasonal burns and relate impacts to quantifiable above and belowground life cycle stages of the study species, ii) isolate and assess the role of smoke, and iii) control for fire intensity and life stage of the study species at each of the treatment levels to enable robust comparison focused on fire season effects. We found that late autumn burns caused complete failure of a cohort in our glasshouse study. Heat alone was not the driver of tuber mortality, because soil heating was similar across all burn seasons, and plants burnt in the three other seasons were able to re-emerge strongly in the growing season after fire. Furthermore, a lack of post-fire emergence was due to tuber mortality, not dormancy. Our results highlight that there is likely an interaction between fire-related heat and the life cycle stage at which burning occurs, especially replacement tuber initiation, that drives post-fire demography. We show that orchids like P. curta had the lowest risk of negative impacts when burnt in the later stages of their growing season, and that an understanding of finer-scale phenological cycles can inform more robust fire management of orchid species.

A Machine Learning Approach to Predict the Occurrence of Forest Fires with Meteorological Parameters

Forest fires have emerged as a considerable challenge in the United States, posing substantial societal, economic, and environmental risks. As a result, the early and accurate prediction of these fires is imperative for management efforts. In this study, we used two Kaggle datasets: the “Algerian Forest Fires Dataset” with fire readings from 2012 and the “Forest Fires Data Set” with readings from 2007. However, because the second data set was originally intended for a regression task, providing approximate area values representing the predicted burned area of the forest fire, we phased the data set out while developing our final model. Ultimately, we used the Algerian Forest Fires Dataset, containing 13 attributes and 244 instances of forest fires in two regions of Algeria. To streamline the analysis, we reduced the number of features to 5, namely, month, temperature, humidity, wind, and rain. Moreover, we developed a Random Forest Classifier model to predict the occurrence of a forest fire, using the data set for training and testing. Performance was compared against Decision Tree, Logistic Regression, and Artificial Neural Network models, using cross-validation. The experiment showed a slight superiority to the Random Forest Classifier approach, achieving an accuracy score of 86.486% and an F1 score of 88.889%. Our approach provides a decimal value representing the probability for fire likelihood. Overarchingly, this research contributes to the advancement of forest fire prediction technologies by leveraging meteorological data.

Reignition characteristics of lignite affected by pre-oxidation and liquid nitrogen cold soaking

The propensity of residual oxidized coal to be reignited within enclosed fire areas in coal mines under liquid nitrogen (LN2) cold soaking remains unclear. Therefore, scanning electron microscopy (SEM), low-temperature nitrogen adsorption (LTNA), and thermogravimetric (TG) experiments were conducted to characterize the pore structure and secondary oxidation of oxidized cold-soaked coal. The results indicate that pre-oxidation or cold soaking alone can promote the generation and merging of pores and make the pore structure more complex, especially when pre-oxidized. However, pore evolution is suppressed and then improves when lignite is simultaneously subjected to pre-oxidation and cold soaking. In particular, the macropore volume and specific surface area decrease and then increase. The cryogenic shrinking of the LN2 results in the collapse of the loose coal matrix, which subsequently blocks the macropores. In contrast, vaporization expansion enhances pore connectivity with continuous LN2 injections, transforming mesopores into macropores, especially in the pore ranges of 2–5 nm and >50 nm. Additionally, pre-oxidation or cold soaking alone improves the oxidizing activity and combustion performance of raw coal. However, continuous cold soaking initially increases and subsequently decreases the characteristic temperatures and activation energy of oxidized coal. Oxidization at 200 °C with one cold soaking can further lower reignition propensity. The average activation energy of oxidized coal decreases by 22.9%–29 % when soaked more than three times. The improvement in combustion property is closely related to the increasing number of macropores because a larger pore volume and specific surface area are conducive to oxygen diffusion and adsorption. Therefore, pre-oxidation and cold soaking promote and inhibit the reignition of coal when performed simultaneously. These results provide theoretical guidance for rational liquid-nitrogen injection to control coal fires.

Exploring the Tar Component Characteristics of Coalfield Fire Residual Coal Under Different Constant Temperature Oxidation

ABSTRACT Due to incomplete combustion of coal, a large amount of tar will be produced in coal fire area, which will cause serious pollution to the environment. In this paper, we dissolve the tar components in the residual coal by solvent extraction technique, analyze the organic components in the residual coal tar at different temperatures by GC-MS, study the characteristics of the residual coal tar components at different temperatures, and analyze the influence of the residual coal tar on the combustion and rekindling characteristics of the fire zone of the coalfield. The results show that: the components of coal combustion residual tar are mainly alkane organics which are easy to be oxidized and volatilized, and the content is more than 55%. At 300°C, the color of residual tar extract is light yellow or yellowish brown, and becomes colorless with the increase of temperature. At 300–500°C, the lower the temperature in the fire zone, the more residual tar in the coal, and the greater the risk of reignition in the extinguishing fire zone. The types of organic compounds in the tar residue from combustion have obvious characteristics at different temperature stages. Organic species have obvious characteristics at different temperature stages. By identifying the temperature stage of the coalfield fire area development, the organic structure characteristics and change trend of the residual coal tar can be deduced, and mastering the organic structure characteristics of the residual tar in the coalfield fire area can also reflect the temperature stage of coal fire area to a certain extent.

Development of Smart Fire Safety System for Vehicles Using IOT

Today, fire accidents often occur in homes and industrial environments, where climate change and human negligence can be predicted. The proposed prototype is designed to detect such fire accidents and remotely extinguish the fire from the user, thus reducing the risk to firefighters. The main idea of ​​this concept is to propose a model that focuses on the cost-effective design and implementation of an automatic fire protection system for electric vehicles. In this system, the fire extinguisher is activated when it detects flame/smoke in the vehicle fire area and extinguishes the fire automatically. There are many reasons for an electric vehicle that can cause fire accidents. The main cause of electric car fires is the battery used in them. There have been many cases of cars catching fire for the reasons mentioned above and ending with the entire vehicle reduced to ashes. The installation of an automatic extinguishing system allows to minimize the financial losses that can arise from a fire and to increase the safety level of the vehicle, passengers and other road users. Keywords : Fire Situation, Controller, Emergency Alert, Accident Prevention, IOT Technology etc.

Fire zone forefront residual tar combustion characteristics and functional group transformation mechanism: Appling the based on thermogravimetric and in-situ high-temperature FTIR

When preventing spontaneous combustion disasters in extinguished coal fire zones, the influence of the tar re-ignition phenomenon is often overlooked. Therefore, in this study, using thermogravimetric analysis and high-temperature (630 °C) in-situ infrared technology, the combustion reactivity and real-time evolution mechanism of key functional groups for tar were deeply discussed under oxygen-lean conditions. Additionally, a novel two-step baseline drift correction method for spectral graphs at high temperatures is proposed. The results showed that tar combustion could be divided into two stages: pyrolysis-volatilization mass loss and crosslinked structure oxidation combustion. Reduced oxygen concentration limits the violent and stable rapid combustion of tar-crosslinked structures and reduces the re-ignition tendency of tar. Among, with a decrease in oxygen concentration, H (burnout performance), Cb (the reaction ability in the early stage of ignition) and S (overall combustion performance) decreased, while Ti (mass loss endpoint temperature), Th(burnout temperature), and HF (combustion stability) increased. This provides information for the selection of a reasonable process to prevent tar re-ignition. The contents of methylidene and aldehyde carbonyl in tar increased by approximately 2 and 3.7 times, respectively, compared to those of raw coal. In the first thermal decomposition stage of tar, the aromatic hydrocarbons were relatively stable under the action of the structural framework, whereas aliphatic hydrocarbons continued to decrease. Before burnout, a decrease in oxygen concentration increased the crosslinking ability of tar and delayed the tar burnout process. The contents of aromatic hydrocarbons and aldehyde groups are highly sensitive to the evolution of the oxygen concentration. Specifically, the Kubelka–Munk value of the aromatic hydrocarbons increased from 0.015 to 0.10, while that of aldehyde carbonyl groups increased from 0 to 0.23. Additionally, in the early stage of tar combustion, the volatile mass loss was basically not affected by the time-scale effect, and mass loss endpoint residual mass was approximately 48.11 %. In the later stage of tar combustion, owing to the cumulative of time-scale effect, the tar re-ignition tendency increased, H, Cb, and S increased, and HF decreased from 1.388 to 1.098. This research is helpful guiding disaster prevention and control of tar re-ignition in a fire area, which leads to reburning in the surrounding area.