Fire Technology最新文献

The paper compares the performance at elevated temperatures of three water based intumescent coatings (IC) exposed to constant heat flux in a cone calorimeter with the performance of a water-based IC which has been heated in a gas furnace according to the standard and the smouldering nominal heating curves, during a previous experimental program. The tests herein presented were carried out on steel plates, with different thickness to vary their section factors, protected with IC layer characterized by different dry film thickness. Despite the IC activated at about 120 °C regardless the heating conditions (i.e., under the cone or in the gas furnace), the type of heating affected the structure of the IC char that formed during the heat exposures: both the expansion of the IC and its equivalent thermal conductivity seems to be dependent on the fire exposure scenarios.

When developing a research roadmap for human behaviour in fires, it is necessary to identify areas that require additional research. A general overview – from a multidisciplinary perspective – of gaps in human behaviour in fires research across multiple contexts is missing. The goal of this paper was to perform a scoping review to identify research gaps and themes in all aspects of human behaviour in fires across contexts. This scoping review included 17 articles. In total, 37 research gaps and 11 research themes for the built environment and community context were identified. The main research gaps are related to cognitive factors, behavioural responses, environmental factors and physical/physiological factors. Also, for all research themes, additional research involving heterogenous populations is required. Furthermore, there is an imbalance in human behaviour in fires studies: most articles were focused on the built environment rather than the community context. Finally, the topic of intoxication has received limited research attention, and data collection methods lack diversity. Future research should not only be done from a multidisciplinary perspective but also interdisciplinary research efforts are required. The availability of more data and knowledge on human behaviour and responses in fires could be beneficial to simulation model developers/users, the general public and fire safety managers.

Wildfire risk and the extent of burned areas have been increasing in the Mediterranean region over recent decades, driven by high temperatures, low humidity, and extreme weather conditions intensified by climate change. Especially Greece, due to the country's diverse natural environment, has recently faced increasingly intense wildfires which have challenged firefighting efforts. The prediction of smoke dispersion can provide crucial information for enhancing fire management operations. In this study, an integrated Air Quality and Fire Modeling System based on WRF-SFIRE-Chem model has been developed to predict the wildfire spread, smoke dispersion and the distribution of PM₁₀ and CO under specific weather conditions that significantly affect the fire by performing simulation scenarios on selected days—based on the Fire Weather Index (FWI) estimation—and specified fire ignition points. Two areas with specific interest were selected: i) the Samaria Gorge in Crete and ii) the cross-border forest area of Skopos in Western Macedonia. Results showed that the large-scale weather conditions and the local weather created by the fire, play a significant role in the pollutants’ dispersion and ground level concentrations. In the case of Samaria gorge, PM₁₀ can reach up 11,238 μg/m³ at Ksiloskalo and 4629 μg/m³ at Agia Roumeli, and the ignition locations of the fire, even if in close distances, can result in different fire behavior and further to dissimilar smoke dispersion in the wider area. In the case of cross border area of Western Macedonia, PM₁₀ can reach up to 2500μg/m³ at Skopos village and 3000μg/m³ at Agios Athanasios in the case of a wildfire event in the attached forest area. The developed fire and air quality modeling system, provides specialised understanding on the prevailing dispersion patterns of PM₁₀ and CO in the regions surrounding the areas of interest, for planning future fire risk management systems, designing efficiency cooperative prevention and evacuation strategies.

Graphical Abstract

Several technologies such as forced ventilation, active fire-fighting systems, and passive fire protection systems are used in current practice to mitigate fire-induced structural damage to concrete liners in roadway tunnels. This paper outlines a new decision-making approach to optimize these strategies by weighing their initial investment and life cycle costs against their relative impact for enhancing the tunnel’s resilience to fire (quantified in terms of post-fire downtime and cost as a function of the severity of fire-induced damage). First, a concrete liner damage assessment tool is developed to account for the presence or lack of active and passive fire protection, as well as realistic uncertainties in the thermal properties of the materials used. Second, both the cost of protection and the potential economic loss due to stochastic vehicle fire hazards are quantified for a single mitigation strategy or a combination of strategies. The economic losses include the direct repair cost and the functionality loss and detour distance due to the duration of tunnel closure, which is determined as a function of concrete liner damage severity and the corresponding repair procedures. Third, a genetic algorithm is used to perform a multi-objective optimization, resulting in a Pareto front as the reference for the decision-making process. The objectives and constraints of the algorithm can be readily modified based on practical engineering requirements. The proposed approach is then used to evaluate the sensitivity of fire protection selection to tunnel geometry, traffic volume and composition, and detour distance during closure.

Lithium-ion batteries (LIBs) overheating caused by fast charging extremely enhances the risk of battery thermal runaway and the resulting fire and explosion accidents, severely threating electric vehicle safety. To relief the temperature rise of batteries during fast charging, forced convection cooling is expected but improper cooling strategy may lead to lithium plating and thermal inhomogeneity. For investigating the LIB electrochemical and thermal characteristics under forced convection condition, a multi-dimensional electrochemical–thermal coupled model of 2.6Ah 18650 LIB is developed in this work, with which effects of charging rate and convection heat transfer coefficient are clarified. From the results, the critical charging rate of lithium plating is 4 C, and with further increased charging rate, nonlinear growth of abnormal electrochemical characteristics related to lithium plating indicating shorten lifetime and enhanced possibility of internal short circuit. At high charging rate, irreversible heat showing difference in different LIB components dominates the total heat generation, causing large temperature rise and uneven temperature distribution inside the LIB, extremely enhancing the risk of over-aging and thermal runaway. Adopting high convection heat transfer coefficient is proved to effectively alleviate the temperature rise at large charging rate, but the augmented levels of heat generation with large difference of thermal conductivity inside and outside the LIB induce a large temperature gradient, causing inhomogeneity in electrochemical characteristics and an enhancement of lithium plating. These findings will provide effective guidance for developing appropriate cooling strategy to achieve reliable fire protection while minimizing the adverse effects of cooling.

At present, there is a lack of fire risk assessment models and effective fire prevention measures for wooden components in historical buildings that are susceptible to fires. This paper combines the physical principles of fire spread and the basic principles of directed graphs to propose the directed graphical combined breadth-first search (DG-BFS) model, which can infer the real-time fire spread situation accurately and quickly. With the assistance of the DG-BFS model, historical building fire risk assessments are conducted using generated spread matrices, taking into account static metrics related to building parameters and dynamic factors associated with environmental conditions. Additionally, it employs node importance metrics, such as in-degree and out-degree, to evaluate the fire risk level of building nodes. In order to prevent and control the spread of the fire under the existing building, the directed graphical model employs a node deletion measure to assess the feasibility of reducing fire risk through the insulation of individual buildings. Through simulations of fire spread in actual villages in Guizhou province, the results demonstrate that the application of the aforementioned methods, combined with fire safety reinforcement of a small number of high-risk buildings, can significantly reduce the number of buildings ignited after a fire. These findings provide a method for improving fire risk assessment in historical wooden building clusters, particularly in cases with limited data, offering valuable guidance for research and practice in related fields.

Occupant evacuation is a critical aspect of fire safety in buildings. Most evacuation strategies and design principles are based on data from adults, leaving gaps in understanding the unique evacuation behaviours of children. This study examines the movement characteristics of kindergarten children (ages 4–7) during evacuation drills in a primary school. Speed and flow were analysed in corridors and through exit doors of varying widths using video recordings. The findings reveal distinct behaviours, such as the absence of personal space and group-based movement, which differ significantly from adults. Correlations were observed between exit door width, density, and flow rates, highlighting that density alone does not fully explain evacuation dynamics. These insights emphasize the need for evacuation models tailored to children, addressing their unique behaviours and the effects of escape route design.

Smoldering fire of forest duff releases substantial amounts of gases, with emissions significantly influenced by fuel properties and combustion conditions. This study investigates the transient emissions of four main gas species (CO₂, CO, CH₄, and NH₃) from smoldering forest duff with four distinct particle size ranges (2 < d₁ ≤ 4 mm, 1 < d₂ ≤ 2 mm, 0.425 < d₃ ≤ 1 mm, and d₄ ≤ 0.425 mm) under controlled laboratory conditions. Based on the real-time mass loss rate (MLR), the combustion process was categorized into three stages: ignition, spread (decline and growth), and burn out. During the relatively steady spread (growth) stage, the geometric mean mass flux of CO₂ and CO for the largest particle size (d₁) was relatively higher than that for the smallest particle size (d₄), while NH₃ and CH₄ from d₁ remained lower. Within the spread (growth) stage, the geometric mean emission factor (EF) calculated by MLR (EF_m) was higher than the EF calculated by the carbon balance approach (EF_b) across all particle sizes, with the discrepancy more pronounced in low carbon content particles (d₁ and d₄). The EF(CO₂)/EF(CH₄) ratios can differentiate the various smoldering stages. For the first time, the transient carbon emission factor (CEF) was calculated using two methods, with CEF_m being found to provide more detailed insights into smoldering combustion dynamics. This study enhances the understanding of the gaseous emissions of forest duff across different particle sizes and examines the discrepancies between EF calculation methods.

Tunnel fires and smoke spread can pose significant risks to individuals trapped within. Traditional tunnel ventilation systems often demand high energy consumption, posing challenges for sustainable carbon reduction. This paper develops a 1:15 scale tunnel model to assess how shaft distance with unpowered ventilation caps influences back-layering length and downstream smoke stratification during a fire. The smoke back-layering length gradually increases with the distance between the double shafts. A theoretical model is derived to determine the distance of smoke spread upstream and the critical wind speed required to control the smoke. The smaller the distance between the double shafts, the more intense the mixing of air and smoke at the smoke thermal stratification interface downstream in a tunnel. This study provides a valuable reference for the use of unpowered ventilation caps to improve building ventilation structures and achieve tunnel smoke control.

Shading shacks are commonly installed in highway tunnels to alleviate sudden lighting variations at portal connections and decrease illumination energy demands. Nevertheless, their effects on longitudinal smoke propagation in adjacent tunnel networks during fire incidents remain poorly understood. This study investigates how shading shacks influence inter-tunnel pollutant transfer and develops a novel Shading Shack Smoke Control System (SSSCS) combining overhead smoke barriers with coordinated exhaust ventilation. Experimental-numerical analyses of 100 m spaced twin tunnels reveal that conventional shading shacks restrict smoke diffusion in tunnel connectors while intensifying cross-tunnel contamination, with CO transfer ratios reaching 48%. The SSSCS demonstrates operational efficacy by improving visual clarity, suppressing CO transfer to 17%, and elevating evacuation safety indices. This systematic solution advances fire smoke management protocols for clustered tunnels equipped with shading infrastructure.