Fire, Volume 7, Issue 7 (July 2024) – 53 articles

This paper aimed to provide technical support for fuel management by exploring different strengths of fuel removal on the physical and chemical properties and flammability of Betula platyphylla forests in the wildland–urban interface. After investigating the northeastern region during the forest fire prevention period in May 2023, a typical WUI area was selected, and three different treatment strengths, combined with a control, were set up to carry out indoor and outdoor experiments for 27 weeks. Compared with previous studies, this study mainly investigated and analyzed the dynamic changes in the physical and chemical properties and fuel flammability after different intensities of treatments on a time scale. By processing and analyzing the data, the following results were obtained. Significant differences existed in the fuel loading of different time-lag fuels over time (p < 0.05). The ash and ignition point of 1 h time-lag fuel after different treatment intensities generally increased first and then decreased, and the higher heat value and ash-free calorific value generally decreased first and then increased. The physical and chemical properties of 10 h and 100 h time-lag fuel fluctuated with time, but the overall change was insignificant. The indicator that had the greatest impact on the combustion comprehensive score for different time-lag fuels was fuel loading. The change in the flammability of dead surface fuel with time varied significantly, and different treatment intensities effectively reduced the fuel’s flammability. The reduction effects, presented in descending order, were as follows: medium-strength treatment > low-strength treatment > high-strength treatment > control check. In conclusion, different treatment intensities have significant effects on the flammability of the fuel, and the medium-strength treatment has the best effect. Considering the ecological and economic benefits, adopting the medium-strength treatment for the WUI to regulate the fuel is recommended. Full article

In small and medium-sized chemical plants, explosions constantly occur owing to runaway reactions because of equipment defects or human errors and so on. Accordingly, in this study, based on a case study of an explosion accident in a polystyrene reactor in South Korea, the dis-charge capacity of hazardous substances during a runaway reaction is reviewed and a method for safely disposing of hazardous substances is proposed. Using an acceleration rate calorimeter, the maximum temperature rise rate during the polystyrene reaction was determined, and it was determined that 355,643 kg/h can flow during a runaway reaction. A 30-inch header size was then selected to consider maximum flow rate, and two 81.4 ${\mathrm{m}}^2$ heat exchangers were selected to completely condense the hazardous substances. As a result, the facilities at the workplace were configured to condense all hazardous substances and discharge them into the atmosphere. If this method is used, it is believed that the lives of workers can be protected by preventing fires and explosions in small and medium-sized chemical plants in which runaway reactions may occur. Full article

Soils are a valuable renewable resource on human timescales, and they interact with distinctive grassland ecosystems characterized by unique biodiversity and essential provision of ecosystem services, such as water supply and carbon sequestration. However, knowledge of the effects of wildfires on soil properties and nutrient availability in the Andes remains limited. Andean grasslands are currently one of the ecosystems of the Peruvian Andes most affected by wildfires. Our objective is to analyze the effect of fire activity on the physicochemical properties of soil and analyze its social context in Cusco, in the southern Andes of Peru. Soil samples were collected during five periods, spanning both the dry and rainy seasons, to characterize changes in soil properties and monitor vegetation recovery post-fire in two local communities dedicated to livestock activities. The vegetation restored after the wildfire was measured by the “step transect” method. Post-fire changes in soil properties indicate slight increases in pH, electrical conductivity, organic matter, nitrogen, phosphorus, and potassium during the onset of the rainy season; thereafter, a gradual reduction in these values was observed. This reduction can be attributed to leaching associated with the seasonal rainfall and runoff regime. Our findings indicate that one-year post-fire, the biomass in burned areas is reduced to 30–46% of the biomass in unburned areas. A complete regeneration is likely to occur in up to 4 years; this assertion is supported by the perceptions of the affected population, as expressed in interviews conducted in the two farming communities. These results are significant for decision-makers formulation of policies and regulations regarding grasslands and their seasonal restoration. Full article

A compression ignition engine generates power by using the auto-ignition characteristics of fuel injected into the cylinder. Although it has high fuel efficiency, it discharges a lot of exhaust emissions such as NO_X and PM. Therefore, there is much ongoing research aiming to reduce the exhaust emissions by using the technologies applied in this regard, such as PCCI, HCCI, etc. However, these methods still discharge large exhaust emissions. The RCCI method, which combines the spark ignition method and compression ignition method, is attracting attention. So, in this work, the objective of this study is to numerically investigate the effect of combustion phase according to the premixed ethanol ratio based on the same total heating value in-cylinder by changing the initial air composition on the formation and oxidation of exhaust emissions in the RCCI engine. The heating value of the premixed ethanol ratio varied from 0% to 40% based on the same total lower heating value in-cylinder in steps of 10%. It was assumed that the ethanol introduced into the cylinder through the premixing chamber was evaporated, and the initial air composition in the cylinder was changed and set. It was revealed that when the premixed ratio based on the same total lower heating value was increased, the introduced fuel amount into the crevice volume with advancing the start of energizing timing was decreased, which increased the peak cylinder pressure. In addition, the ignition delay was also longer due to the low cylinder temperature by the evaporation latent heat of the ethanol, which reduced the compression loss, so the IMEP value was increased. The rich equivalence ratio had a narrow distribution in the cylinder, which caused a reduction in cylinder temperature, so the NO formation amount was reduced. The ISCO value increased the increase in premixed ethanol ratio based on the same total lower heating value in-cylinder because the flame propagation of ethanol by combustion of diesel did not work well, and the CO formed by combustion was slowly oxidized due to the cylinder’s low temperature as a result of the evaporation latent heat of ethanol. From these results, the optimal operating conditions for simultaneously reducing the exhaust emissions and improving the combustion performance were judged such that the start of energizing timing was BTDC 23 deg, and the premixed ethanol ratio based on the same total lower heating value in-cylinder was 40%. Full article

Given the increasingly severe global fires, the accurate detection of small and fragmented cropland fires has been a significant challenge. The use of medium-resolution satellite data can enhance detection accuracy; however, key challenges in this approach include accurately capturing the annual and interannual variations of burning characteristics and identifying outliers within the time series of these changes. In this study, we focus on a typical crop-straw burning area in Henan Province, located on the North China Plain. We develop an automated burned-area detection algorithm based on near-infrared and short-wave infrared data from Landsat 5 imagery. Our method integrates time-series outlier analysis using filtering and automatic iterative algorithms to determine the optimal threshold for detecting burned areas. Our results demonstrate the effectiveness of using preceding time-series and seasonal time-series analysis to differentiate fire-related changes from seasonal and non-seasonal influences on vegetation. Optimal threshold validation results reveal that the automatic threshold method is efficient and feasible with an overall accuracy exceeding 93%. The resulting burned-area map achieves a total accuracy of 93.25%, far surpassing the 76.5% detection accuracy of the MCD64A1 fire product, thereby highlighting the efficacy of our algorithm. In conclusion, our algorithm is suitable for detecting burned areas in large-scale farmland settings and provides valuable information for the development of future detection algorithms. Full article

Functionally Graded Concrete (FGC) allows for a significant reduction in the mass of concrete components while maintaining their structural and functional requirements and improving recycling capacity. This is achieved by inserting spherical mineral hollow bodies into the structure where no material is required. Within the scope of this work, the behavior of FGC slabs exposed to fire is investigated both experimentally and numerically and compared to a corresponding solid cross-section. Therefore, FGC specimens are placed in a test furnace and subjected to fire exposure for 90 min. The temperature distribution, bending load-bearing capacity, and spalling behavior are investigated. The results of the numerical simulation of the solid cross-section are in good agreement with the values provided in the building code. However, for the FGC cross-section, differences in temperature at characteristic measurement points between the experimental and numerical results are observed, presumably due to convection. The experimental results suggest that the bending load-bearing capacity of the investigated FGC cross-section could be potentially greater than that of a corresponding solid cross-section. Furthermore, as expected through analytical analysis, the fire tests confirm that no spalling of the FGC specimens occurred. Full article

This study investigates the applicability of eco-friendly silicone materials with improved flame retardancy as interior materials for Korean urban railway vehicles, focusing on developing nonslip pads for seats made of non-combustible materials. Fire safety standards vary worldwide, necessitating country-specific testing and analysis. For application to the interior of railway vehicles in Korea, technical standards for the flame-retardant performance of railway vehicles were evaluated, and nonslip pads for seats were tested by comparing two types of flame-retardant silicone. In addition to fire property testing on a specimen basis, experimental verification was performed on a full chair assembly including silicone pads. Passenger comfort testing through pressure measurements was also conducted alongside fire safety performance testing The actual fire test showed that the maximum average heat release rate value was about 20% lower than the standard’s upper limit. Using flame-retardant silicone pads enhances fire safety and passenger comfort, satisfactorily meeting the required performance standards for Korean railway vehicles. Full article

Forest fire is a significant global natural disaster, and unmanned aerial vehicles (UAVs) have gained attention in wildfire prevention for their efficient and flexible monitoring capabilities. Proper UAV patrol path planning can enhance fire-monitoring accuracy and response speed. This paper proposes a probabilistic path planning (PPP) module that plans UAV patrol paths by combining real-time fire occurrence probabilities at different points. Initially, a forest fire risk logistic regression model is established to compute the fire probabilities at different patrol points. Subsequently, a patrol point filter is applied to remove points with low fire probabilities. Finally, combining fire probabilities with distances between patrol points, a dynamic programming (DP) algorithm is employed to generate an optimal UAV patrol route. Compared with conventional approaches, the experimental results demonstrate that the PPP module effectively improves the timeliness of fire monitoring and containment, and the introduction of DP, considering that the fire probabilities and the patrol point filter both contribute positively to the experimental outcomes. Different combinations of patrol point coordinates and their fire probabilities are further studied to summarize the applicability of this method, contributing to UAV applications in forest fire monitoring and prevention. Full article

This paper investigates the impact of window partition walls on the spread of fire on building facades under the impact of environmental wind through Fire Dynamics Simulator simulation experiments. A four-story building model was constructed using a Fire Dynamics Simulator incorporating six different wind speed conditions and six different partition wall widths. The fire-blocking performance of window partition walls of varying widths was systematically compared and analyzed, and the data indicated: (1) Under calm wind conditions, the installation of window partition walls is observed to facilitate the vertical spread of facade fires. Moreover, as the width of these partition walls increases, this facilitative effect becomes increasingly prominent; (2) Under wind speeds of 0 to 5 m/s, the temperature on the leeward side is lower when window partition walls are present than when they are absent. This indicates that window partition walls inhibit the horizontal spread of building facade fires, and wider window partition walls have better horizontal fire resistance performance. Full article

Whether noncombustible or combustible construction is used, the presence of combustible materials is likely to be used for various reasons, such as interior finishes, flooring, and insulation. Consequently, how regulations consider the degree of combustibility in their fire classifications will influence the level of fire safety provided in these buildings and the exchanges between all actors in the construction sector. In North America, the regulation of combustibility is primarily governed by surface flame spread assessed through the Steiner tunnel test. While there is a growing prevalence of calorimetric methods globally, their incorporation into North American building codes remains notably limited. Based on ISO 5660-1 cone calorimeter test results of twenty commercially available North American building materials, a comparative study was conducted between the Canadian flame spread classification and the classifications in Japan, New Zealand and the European Union (Euroclass). The tests and their limitations are described herein, as well as the conceptual frameworks. The results suggest that as materials’ combustibility levels increase, the level of agreement between classifications decreases and remains binary. The choice between the material and system scales is crucial for determining the effective development and implementation of regulations. Full article

Research on wildfires and social vulnerability has gained significant importance due to the increasing frequency and severity of wildfires around the world. This study investigates the dynamic changes in social vulnerability to wildfires over a decade in Idaho, USA, utilizing GIS-based tools and a quasi-experimental design. We assess the evolving nature of social vulnerability at a local scale, emphasizing both spatial and temporal dynamics. Initially, we identified social vulnerability trends in relation to varying levels of wildfire risk. The research then employs propensity score matching to contrast areas affected by wildfires in 2012 with similar non-affected regions, thereby quantifying the short-term shifts in social vulnerability post-wildfires. The results indicate that regions with a high wildfire risk may display elevated vulnerability, characterized by an increase in unemployment rates and a reduction in high-income households. These findings tentatively demonstrate the compounded effect of wildfires on already vulnerable populations, highlighting the critical need for targeted interventions. Ultimately, this study underscores the importance of integrating dynamic social vulnerability assessments into wildfire management and planning, aiming to enhance community resilience and equitable resource distribution in the face of escalating wildfire threats. Full article

Wildfires have a significant influence on ecosystems globally, shaping vegetation, biodiversity, landscapes, soil properties, and other ecosystem processes. Despite extensive research on different aspects of wildfires, the edges of burned areas remain understudied, even though they involve complex dynamics. In this study, we analyzed the post-fire vegetation recovery across the edges of a large wildfire in a Mediterranean area. The investigations were focused on patches of woodlands that, in a previous study, showed a normalized burn ratio (NBR) decline one year after the fire. Field vegetation surveys were carried out in areas characterized by different NBR recovery rates and in areas outside the burned area as controls. Five hypotheses were tested, identifying delayed tree mortality as a key factor linked to NBR decline, particularly in low-severity fire zones in proximity to the fire edges. Delayed mortality, observed predominantly near the edges, may also affect unburned or less severely burned patches within the main fire perimeter, highlighting the need for ongoing monitoring. As these areas play a crucial role in the post-fire succession and vegetation dynamics, understanding the second-order effects of a fire is imperative for effective ecosystem management. This study underscores the importance of the long-term assessment of fire impacts, emphasizing the necessity of field surveys alongside remote sensing. Continued observation is essential to elucidate the enduring impacts of wildfires and to facilitate informed restoration strategies. Full article

In the current context of extreme wildfires, understanding fire behavior at a territorial level has proven crucial for territory planning. This type of analysis is usually conducted by analyzing past wildfire statistics. In this study, we forego the past information related to wildfires and analyze, instead, the behavior of the entire territory in the face of wildfires. This allows for the distribution of ignition points to be systematized and for typical and atypical weather scenarios to be considered. This analysis relies on the use of wildfire simulation software. Ignition points used for the simulations were distributed using a systematic 1 × 1 km grid throughout the whole study area. Wildfires were simulated for each ignition point using eight different weather scenarios representing both typical and atypical weather conditions. The fire behavior on the territory was analyzed using rate of spread and intensity parameters for each simulated wildfire. It was observed that this territory is extremely prone to large wildfires both in typical and atypical weather conditions and that there is a tendency for extreme behaviors to develop. Some features were identified as prevention issues that ought to be addressed. This study develops a strategy to evaluate, in a systematic manner, the response of the territory to the threat of wildfires. Full article

Until the late 20th century, the idea of identifying wildfires in deep time was not generally accepted. One of the basic problems was the fact that charcoal-like wood fragments, so often found in sedimentary rocks and in coals, were termed fusain and, in addition, many researchers could not envision wildfires in peat-forming systems. The advent of Scanning Electron Microscopy and studies on modern charcoals and fossil fusains demonstrated beyond doubt that wildfire residues may be recognized in rocks dating back to at least 350 million years. Increasing numbers of studies on modern and fossil charcoal assemblages from the 1970s through the 1990s established the potential importance of wildfires in the fossil record, using Carboniferous examples in particular. Since the 1990s, extensive progress has been made in understanding modern wildfires and their byproducts. New techniques to study ancient charcoals have allowed considerable progress to be made to integrate modern and ancient fire studies, both before and after the evolution of mankind. Four important developments have made a reassessment of Carboniferous wildfires necessary: the recognition of the role of atmospheric oxygen in controlling the occurrence of wildfire; the development of new microscopical techniques allowing more detailed anatomical data to be obtained from charcoal; the integration of molecular studies with the evolution of fire traits; and new developments in or understanding of post-fire erosion/deposition systems. Full article

California has experienced a surge in wildfires, prompting research into contributing factors, including weather and climate conditions. This study investigates the complex, multiscale interactions between large-scale climate patterns, such as the Boreal Summer Intraseasonal Oscillation (BSISO), El Niño Southern Oscillation (ENSO), and the Pacific Decadal Oscillation (PDO) and their influence on moisture and temperature fluctuations, and wildfire dynamics in California. The combined impacts of PDO and BSISO on intraseasonal fire weather changes; the interplay between fire weather index (FWI), relative humidity, vapor pressure deficit (VPD), and temperature in assessing wildfire risks; and geographical variations in the relationship between the FWI and climatic factors within California are examined. The study employs a multi-pronged approach, analyzing wildfire frequency and burned areas alongside climate patterns and atmospheric conditions. The findings reveal significant variability in wildfire activity across different climate conditions, with heightened risks during specific BSISO phases, La-Niña, and cool PDO. The influence of BSISO varies depending on its interaction with PDO. Temperature, relative humidity, and VPD show strong predictive significance for wildfire risks, with significant relationships between FWI and temperature in elevated regions (correlation, r > 0.7, p ≤ 0.05) and FWI and relative humidity along the Sierra Nevada Mountains (r ≤ −0.7, p ≤ 0.05). Full article

The risk of flammable dangerous liquids stored on the industrial premises escaping into the environment in the event of major industrial accidents must be minimized. Such a risk reduction result can be achieved by the use of safety barriers, such as a remediation bund area, which can retain, collect and store the released material. The careful determination of design parameters of this installation is of great importance. Therefore, this study–based on the analyses of applicability of existing guidelines (SPCC and HSNOCOP 47)—will propose a new sizing calculation methodology to design optimal and efficient remediation bund parameters, including the remediation bund wall height and distance between the remediation bund and the storage tank walls. The design parameters are defined by applying Toricelli’s theorem and their practical compliance is tested using consequence analysis simulation software ALOHA 5.4.7 covering three possible major accident scenarios. As a result of the newly proposed methodology, the risk of overflow through the remediation bund wall can be excluded and higher effectiveness of the application of firefighting and technical rescue intervention activities can be ensured. The results of present research ultimately serve to prevent major industrial accidents and eliminate their possible harmful environmental impact. Full article

Chemical looping combustion (CLC) has been validated as one of the most promising technologies for fossil fuel combustion, which can produce high-purity CO₂ streams ready for capture and sequestration in power production. The selection of an appropriate oxygen carrier is one of the most important issues for the CLC process, and the reduction kinetics investigation of the oxygen carrier with fuel gas can provide the basis for CLC reactor design and simulation optimization. In this study, copper ore was chosen as an oxygen carrier, and the oxygen release property of copper ore under a nitrogen environment at various temperatures (1073–1193 K) was first investigated in a thermogravimetric analyzer (TGA). Subsequently, the reduction kinetics of copper ore with CO and H₂ were evaluated by the TGA at temperatures ranging from 773 K to 1073 K, using a continuous stream of 5, 10, 15, 20, 25, and 30 vol. % of CO or H₂ balanced by CO₂ or N₂. It was found that the reaction rates of these reactions accelerated with the increase in temperature and fuel gas concentration in inlet gas. Both the oxygen release process of copper ore and the reduction process of copper ore with reducing gases can be described by the unreacted shrinking core model (USCM). The reaction mechanism function for the oxygen-releasing and reduction process of copper ore oxygen carrier was varied. The activation energy of the oxygen-releasing process, reduction process with CO, and reduction process with H₂ were calculated as 99.35, 5.08, and 4.28 kJ/mol, respectively. The pre-exponential factor ranged from 1.96 × 10⁻¹ to 1.84 × 10³. The reaction order depended on the fuel gas, which was 1 and 0.86, respectively, for reaction with CO and H₂. Full article

The increasing concerns about CO₂ emissions and climate change have pointed out the urgency of promoting sustainability in the building sector. One promising solution to enhance the energy efficiency of buildings and diminish environmental impact is the integration of phase-change materials (PCMs) into ventilated façade systems. This review article critically examines the current state of research on this innovative approach, with a particular focus on fire safety considerations. The paper explores the integration of PCM into ventilated façades, highlighting the potential for significant improvements in energy consumption, thermal comfort, and reductions in CO₂ emissions. However, the flammability of PCMs introduces substantial fire safety challenges that must be addressed to ensure the safe application of this solution. The fire safety of both ventilated façades and PCMs is approached, followed by specific fire safety concerns when PCMs are integrated into ventilated façade systems. The conclusion states that while the integration of PCMs into ventilated façades offers substantial environmental benefits, attention to fire safety is essential. This necessitates the implementation of rigorous fire protection measures during the design and construction phases. By addressing both the environmental advantages and fire safety challenges, this review aims to provide a comprehensive understanding of the potential and limitations of PCM-integrated ventilated façades, offering valuable insights for researchers, engineers, and policymakers in the field of sustainable buildings. Full article

Wildfires significantly influence the environmental distribution of various elements through their fire-induced input and mobilization, yet little is known about their effects on the forest floor in Siberian forests. The present study evaluated the effects of spring wildfires of various severities on the levels of major and minor (Ca, Al, Fe, S, Mg, K, Na, Mn, P, Ti, Ba, and Sr) trace and ultra-trace (B, Co, Cr, Cu, Ni, Se, V, Zn, Pb, As, La, Sn, Sc, Sb, Be, Bi, Hg, Li, Mo, and Cd) elements in the forest floors of Siberian forests. The forest floor (Oi layer) samples were collected immediately following wildfires in Scots pine (Pinus sylvestris L.), larch (Larix sibirica Ledeb.), spruce (Picea obovata Ledeb.), and birch (Betula pendula Roth) forests. Total concentrations of elements were determined using inductively coupled plasma–optical emission spectroscopy. All fires resulted in a decrease in organic matter content and an increase in mineral material content and pH values in the forest floor. The concentrations of most elements studied in a burned layer of forest floor were statistically significantly higher than in unburned precursors. Sb and Sn showed no statistically significant changes. The forest floor in the birch forest showed a higher increase in mineral material content after the fire and higher levels of most elements studied than the burned coniferous forest floors. Ca was a predominant element in both unburned and burned samples in all forests studied. Our study highlighted the role of wildfires in Siberia in enhancing the levels of geochemical elements in forest floor and the effect of forest type and fire severity on ash characteristics. The increased concentrations of elements represent a potential source of surface water contamination with toxic and eutrophying elements if wildfire ash is transported with overland flow. Full article

After a fire breaks out, pedestrians simultaneously move towards the exit and quickly form a crowded area near the exit. With the intensification of pedestrians’ tendencies towards unfair competition, there is an increase in pushing and collisions within the crowd. The possibility of stampedes within the crowd also gradually increases. Analyzing the causes and psychological tendencies behind pedestrian pushing and collisions has a positive effect on reducing crowd instability and improving evacuation efficiency. This research proposes a modified social force model considering the unfair competition tendency of pedestrians. The model considers factors such as the gap between pedestrians’ actual and maximum achievable speed, effective radius, and their distance from the exit. In order to overcome the shortage of “deadlock” in the classical social force model in a high-density environment, this research introduces the feature of variable pedestrian effective radius. The effective radius of pedestrians dynamically changes according to the density of the surrounding crowd and queuing time. Through validation, the evacuation efficiency of this model aligns well with the actual situation and effectively reflects pedestrians’ pushing and squeezing behaviors in high-density environments. This research also analyzes how to strategically arrange obstacles to mitigate the exacerbating effect of unfair pedestrian competition on exit congestion. Five experiments were conducted to analyze how the relative position of obstacles and exits, the number of evacuation paths, and the size of the obstacle-free area before the exit affect evacuation efficiency in the presence of unfair pedestrian competition. The results show that evacuation efficiency can be improved when obstacles play a role in guiding or reducing the interaction of pedestrians in different queues. However, when obstacles hinder pedestrians, the evacuation efficiency is reduced to a certain extent. Full article

With the advancement of society and the rapid urbanization process, there is an escalating need for effective fire detection systems. This study endeavors to bolster the efficacy and dependability of fire detection systems in intricate settings by refining the existing You Only Look Once version 5 (YOLOv5) algorithm and introducing algorithms grounded on fire characteristics. Primarily, the Convolutional Block Attention Module (CBAM) attention mechanism is introduced to steer the model towards substantial features, thereby amplifying detection precision. Subsequently, a multi-scale feature fusion network, employing the Adaptive Spatial Feature Fusion Module (ASFF), is embraced to proficiently amalgamate feature information from various scales, thereby enhancing the model’s comprehension of image content and subsequently fortifying detection resilience. Moreover, refining the loss function and integrating a larger detection head further fortify the model’s capability to discern diminutive targets. Experimental findings illustrate that the refined YOLOv5 algorithm attains accuracy advancements of 8% and 8.2% on standard and small target datasets, respectively. To ascertain the practical viability of the refined YOLOv5 algorithm, this study introduces a temperature-based flame detection algorithm. By amalgamating and deploying both algorithms, the ultimate experimental outcomes reveal that the integrated algorithm not only elevates accuracy but also achieves a frame rate of 57 frames, aligning with the prerequisites for practical deployment. Full article

The synthesis and dissociation of methane hydrate and carbon dioxide hydrate were studied. Nonflammable gas hydrates can be used to extinguish flames in confined spaces. To increase the extinguishing efficiency, it is necessary to increase the dissociation rate (gas release rate) by using surfactant. The work investigates gas hydrates synthesized using sodium dodecyl sulfate (SDS). Experimental studies were carried out in wide ranges of surfactant concentration, the number of the stirrer revolutions and the initial water volume. To achieve the maximum rate of synthesis and dissociation, optimization of the specified parameters was performed. The influence of the key parameters on the dissociation rate was investigated experimentally and theoretically. The novelty of the work lies in solving a complex of interrelated tasks on the synthesis and dissociation of gas hydrate. It is shown that in order to achieve the maximum dissociation rate of carbon dioxide hydrate, it is necessary to optimize the following parameters: the diameter of the particles and their porosity, the porosity of the layer and the external heat flux. Full article

The use of agroforestry biomass provides several advantages, both from an environmental point of view, in terms of the mitigation of global warming, and in terms of a circular economy for agricultural or agroforestry companies that reuse pruning residues as a source of energy. However, even if the use of energy pellets resulting from the pruning residues of various agroforestry species has excellent potential for the valorization of agricultural by-products, the physicochemical characteristics of these pellets have been scarcely studied by the scientific community. In this context, this study aims to assess the valorization potential of various lignocellulosic material residues produced during agroforestry activities. The objectives of the study include evaluating the chemical and physical characteristics of pellets produced with different mixtures of agroforestry biomass (olive, citrus, black locust, poplar, paulownia, etc.) in order to determine the optimal pellet blend from an energy and physicochemical perspective. The results of this study demonstrate that this comprehensive analysis provides valuable information on the optimization of biomass mixtures for better energy valorization, addressing both compositional and combustion-related challenges. In fact, it is observed that the addition of citrus and olive biomass to the various mixtures increases their energy potential. Furthermore, all of the pellets analyzed are found to possess an adequate and useful durability index (PDI) for their handling during storage and transport operations. This study demonstrates that olive and citrus pruning residues can be used to improve biomasses that have poor suitability in energetic, physical, and chemical terms. Further studies could be useful to understand which specific interaction mechanisms have an influence on emissions in order to optimize mixtures using different biomass sources for sustainable energy production. Full article

Forest fires can profoundly impact the hydrological response of river basins, modifying vegetation characteristics and soil infiltration. This results in a significant increase in surface flow and channel runoff. In response to these effects, many researchers from different areas of earth sciences are committed to determining emergency measures to rehabilitate river basins, intending to restore their functions and minimize damage to soil resources. This study aims to analyze the mapping detection capacity of burned areas in a river basin in Brazil based on images acquired by AMAZÔNIA-1/WFI and the AQ1KM product. The effectiveness of the AMAZÔNIA-1 satellite in this regard is evaluated, given the importance of the subject and the relatively recent introduction of the satellite. The AQ1KM data were used to analyze statistical trends and spatial patterns in the area burned from 2003 to 2023. The U-Net architecture was used for training and classification of the burned area in AMAZÔNIA-1 images. An increasing trend in burned area was observed through the Mann–Kendall test map and Sen’s slope, with the months of the second semester showing a greater occurrence of burned areas. The NIR band was found to be the most sensitive spectral resource for detecting burned areas. The AMAZÔNIA-1 satellite demonstrated superior performance in estimating thematic accuracy, with a correlation of above 0.7 achieved in regression analyses using a 10 km grid cell resolution. The findings of this study have significant implications for the application of Brazilian remote sensing products in ecology, water resources, and river basin management and monitoring applications. Full article

In this study, a novel gas burner combining air swirl and an inverse diffusion flame (IDF) is designed for industrial applications. Numerical simulations using the Reynolds-averaged Navier–Stokes (RANS) method and simplified reaction mechanisms are conducted to predict the turbulent flow and combustion performance of the burner. Detailed flow structures, flame structures and effects of burner configurations are examined. The simulation results indicate that the swirl action of the burner creates a central recirculation zone and two external recirculation zones at the burner head, which stabilize combustion. The tangential velocity is minimal at the center of the burner and decreases with increasing distance from the outlet. As the distance from the exit increases, the maximum tangential velocity gradually decreases, and the peak value shifts towards the wall. This decrease in tangential velocity with axial distance signifies the gradual dissipation of the swirl effect, which disappears near the chamber outlet. The comparisons reveal that altering the number of burner fuel nozzles is more effective in reducing NO emissions than changing the inclination angle of the fuel nozzles, in the given conditions. Favorable combustion conditions are achieved when there are 16 fuel nozzles and the nozzle inclination angle is 60°, resulting in a 28.5% reduction in NO emissions at the outlet, compared to the reference condition. Full article

The unprecedented wildfires of 2017 in Portugal, particularly affecting the Centre Region, resulted in more than 100 deaths and numerous other dramatic socioeconomic and environmental impacts. Due to the unparalleled magnitude of these events, the extent of the burned area, and the catastrophic consequences, forest and fire management were placed at the center stage of public and political concerns, receiving wide mass media attention and amplification likely to shape public opinion and influence policy decisions. Through a quasi-qualitative content analysis approach, this article focuses on the media narratives conveyed by the news issued over two years (N = 1056) by eight newspapers of different periodicities and geographical scopes regarding the wildfires of October 2017 in the Matas do Litoral—coastal public-managed forest areas located in the Centre Region of Portugal. The analysis focuses on three main dimensions: the agents and actors mentioned and their power-related positions, the geographical coverage of the newspapers, and the relevance ascribed to emotions and feelings in the media narratives about the wildfires. The results demonstrate the relevance attributed in media narratives to the views of institutional agents and the negligence of local people’s voices. When particularly highlighting the material impacts of the wildfires, media narratives tended to focus less on people’s emotions and other non-tangible issues. The variation in these narratives according to the geographical scope of the newspapers and the publication time of the news strongly points out the need to address the heterogeneous character of the media coverage of wildfires. Full article

In order to elucidate the overpressure and fire hazard effects of gas explosion in a congested room, the effects of gas concentration and room layout on a gas explosion in a kitchen were studied by CFD. The results showed that the flow field parameters in a kitchen exhibited an initial increase followed by a decrease as the gas concentration increased. The maximum gas flow rate recorded within the chamber was 390 m/s, while the corresponding maximum flame propagation rate and peak pressure reached 289.86 m/s and 30.95 kPa, respectively. The difference in the flow field induced by the concentration was further enhanced by the presence of congested materials. Additionally, the room layout influenced the gas congestion’s blowout effect due to variations in turbulence intensity and flammable gas volume caused by significant changes in the congestion within the room. Specifically, when the gas concentration was 10%, the order of indoor gas flow rate and flame combustion rate were II > U > L > I, while the turbulent kinetic energy and explosive overpressure followed the order I > II > L > U. The results are of great significance for the disaster assessment and accident prevention of natural gas explosion in civil kitchens. Full article

Although the influence of climate on the fire regime is unanimously recognized, most publications and studies on this influence are on a global scale. Therefore, this study aims to demonstrate the role of climate in wildfire incidence at the country and regional scale using multivariate statistical analysis and machine learning methods (clustering and classification algorithms). Mainland Portugal was chosen as a case study due to its climate and because it is the European region most affected by wildfires. The results demonstrate the climate signature in the spatial and temporal distribution of the wildfire incidence. The conclusions of the study include (i) the existence of two pyro-regions, with different types of climate (Csb and Csa) composed of NUTS II regions: the northern region composed of the Norte and Centro regions and the southern region composed of Alentejo and Algarve; (ii) the intra-annual variability in the wildfire incidence, characterized by two peaks, one in the spring and the other in the summer, are a consequence of the country’s type of climate; and (iii) how the annual cycle of wildfire incidence varies over the years depends on the weather conditions throughout each year. These results are of fundamental importance for wildfire managers, especially in the context of climate change. Full article

Hydrogen (H₂) is considered a suitable substitute for conventional energy sources because it is abundant and environmentally friendly. However, the widespread adoption of H₂ as an energy source poses several challenges in H₂ production, storage, safety, and transportation. Recent efforts to address these challenges have focused on improving the efficiency and cost-effectiveness of H₂ production methods, developing advanced storage technologies to ensure safe handling and transportation of H₂, and implementing comprehensive safety protocols. Furthermore, efforts are being made to integrate H₂ into the existing energy infrastructure and explore new opportunities for its application in various sectors such as transportation, industry, and residential applications. Overall, recent developments in H₂ production, storage, safety, and transportation have opened new avenues for the widespread adoption of H₂ as a clean and sustainable energy source. This review highlights potential solutions to overcome the challenges associated with H₂ production, storage, safety, and transportation. Additionally, it discusses opportunities to achieve a carbon-neutral society and reduce the dependence on fossil fuels. Full article

Although current EU regulations, such as EU Directive 2015/1189 on the eco-design of solid fuel boilers and Directive 2015/1188, in accordance with the Machinery Directive 2006/42/EC, require manufacturers to meet specific emission requirements for CE marking, the routine and regular onsite testing of household heating appliances is still not mandatory in many EU countries. This research endeavour addressed this gap by evaluating the effectiveness of the Bacharach method as a rapid and cost-effective tool for assessing flue gas quality, particularly in terms of particulate matter mass concentration. This study also compared the results of the Bacharach method with those obtained from two commercially available portable analysers. The research outcomes demonstrate that the Bacharach method, in combination with an innovative evaluation approach, offers a viable solution, enabling the swift and economical assessment of flue gas quality with the primary objective of determining the boiler class according to the limits specified by standard EN 303-5 under operating conditions. The modified Bacharach method for measuring TSP in solid fuel-fired boilers provides qualitatively similar results to the commercially used SM500 and STM225 instruments. The modified Bacharach methodology was primarily developed for comparison to the boiler class 3 limit (i.e., 125 and 150 mg/m³). The study revealed that the modified Bacharach method, when applied to biomass-based boilers, exhibited higher accuracies in the case of classification into classes 3 and 4, whereas fossil fuel-based boilers demonstrated higher accuracy in the case of class 5 limits. Full article