Fire Technology最新文献

In the past decade, communities have detected volatile organic compounds (VOCs) in their water distribution systems following wildfire impacts (e.g. system damage and depressurization). This study outlines a comprehensive experimental framework developed to quantify the effects of localized water system depressurization (e.g. loss of pressure at a house) as a mechanism for VOC contamination in water systems following wildfire events. The methodology employs a modular, instrumented vacuum test setup connected to a compartment with a consistent, well-characterized fuel load. The modular design facilitates targeted experimentation, enabling researchers to assess specific parameters influencing VOC contamination during local depressurization. The integration of sensors and video imagery enables researchers to quantify results within specific fire exposures and depressurization conditions. The integrated sensors and imagery allows for conditions—such as temperature, airflow rate, and material deformations—to be continuously monitored. Proposed sampling protocols provide methods for post-test sampling to quantify total system exposure to VOCs from the burning compartment and the response of the system components to that exposure, such as the levels of VOCs leached from pipes post-exposure and how system recovery techniques may influence concentrations of VOCs leached. Though these methods are presented in the context of VOC contamination from localized depressurization, the framework can be adapted to investigate other water system concerns following pressure loss, such as pathogens, turbidity, and heavy metals. The presented methodology provides a preliminary framework for assessing depressurization-induced contamination and the effectiveness of recovery strategies in fire-affected water systems.

This work investigates the evolution of gas temperature and flow field characteristics inside the tunnel due to an on-fire moving train at varying speeds and fuel pan sizes. A 1:15 model scale experimental series using methanol liquid has been carried out with a train speed range from 0.0 m/s to 2.0 m/s. The results show that the piston wind and return wind generated due to the moving train had a significant influence on the maximum gas temperature rise of the tunnel. Different from the stationary fire source scenario, the ceiling gas temperature evolution shows a sudden peak followed by a decrease in temperature due to the increased return wind and flame tilt angle. The vertical gas temperature decreases with an increased vertical distance from the tunnel ceiling due to the formation of a smoke layer near the ceiling. At increasing train speed, the increased piston wind disrupts the smoke stratification phenomenon, causing the relative decay rate of vertical temperature to differ. This study helps to understand the gas temperature evolution and flow field characteristics due to a moving train fire in naturally ventilated tunnels.

Retrieving precise fire safety regulations is essential for the relevant staff in smart city development and building safety management. Requesting information via large language models (LLMs) is popular nowadays. However, the LLMs present limitations in handling fire safety regulations queries due to the complex and strict numerical requirements in fire safety regulations. We introduce a triple-phase precision control strategy as a novel approach to ensure accurate and reliable regulation queries. First, we convert fire safety regulations into a standardized JSON format to ensure data consistency and accessibility, as well as friendly to computer programming language. Second, we develop a deterministic matching algorithm to accurately align user queries with relevant regulation clauses. Finally, LLMs generate summaries according to the matching clauses and a preset prompt, preventing hallucination risks. Experimental results demonstrate that our proposed framework outperforms general approaches, including commercial LLM clients with Retrieval-Augmented Generation capabilities (which use text chunking techniques, either integrating web-based retrieval or allowing local file uploads), as well as pure LLM methods, in reducing errors and improving precision. The proposed scheme not only enhances the accuracy of fire safety regulations retrieval but also provides solutions for other domains with precision-critical requirements, advancing the application of AI in regulatory compliance.

Matrix interference remains a key issue in gasoline identification. Our previous research has demonstrated that styrene-butadiene rubbers (SBrs) can cause remarkable interference with gasoline identification, with the extent of this interference being highly dependent on the chemical structure of the SBrs. To trace the origins of the interference, the pyrolysis mechanism of SBrs with varying butadiene concentration was inferred based on results concerning pyrolysis products and thermal stability, and factors of the pyrolysis mechanism and chemical structure of the SBrs were involved together to explain the chemical-structure-dependent matrix interference extent reported previously. The results indicated that the total amount of butadiene in SBrs was a key point for causing interference with gasoline identification. The pyrolysis products of SBr 1205 with the highest butadiene concentration were long-chain straight alkenes of varying lengths. Meanwhile, SBr 1205 exclusively possessed cis-structure, resulting in the majority of its pyrolysis products being cis-structures, which were speculated to be precursors to form aromatic compounds by cyclization during combustion. The study revealed that the chain-structured cis-alkenes with varying lengths generated during pyrolysis played an important role in causing remarkable interference with gasoline identification, which provided valuable insights for understanding and predicting the matrix interference for fire debris analysis.

Graphical Abstract

A fire door is a critical building component installed within compartments to prevent the spread of fire to adjacent areas. During a fire event, these doors experience bending deformation due to temperature differences between exposed and unexposed surfaces. The maximum deflection typically occurs at the top corner on the lock side, causing the door leaf to bend away from the supporting frame. Such out-of-plane deformation compromises the integrity of the door, reducing its fire-resistance performance. While previous research, including a simplified thermomechanical model proposed by Italian researchers in 2017, investigated the thermomechanical behavior of fire doors, this study advances the understanding further. Specifically, (1) an enhanced thermomechanical model is developed by incorporating three previously neglected factors: door width, temperature-dependent elastic modulus, and the gap size between the door leaf and the frame; (2) the developed model demonstrates high accuracy, correlating strongly ((r^{2} = 0.9)) with deformations measured in fire-resistance tests; and (3) a robust design approach for fire doors is presented, ensuring sustained fire-resistance irrespective of gap variations. Experimental validation confirmed that the robustly designed fire doors exhibited approximately 5 mm less deformation compared to standard fire doors.

A tunnel during construction is a typical long-narrow space with one closed end. Due to the cost-effectiveness and convenience, press-in ventilation is the most widely used in tunnels during construction. In the case of fire in tunnels during construction, press-in ventilation needs to simultaneously suppress the smoke back-layering length on the upstream side and maintain the smoke stratification stability on the downstream side. Based on the two-region theoretical model of fire-induced smoke in confined spaces, the relative flow of smoke and air on the downstream side is analyzed under press-in ventilation using the hydrostatic pressure difference and mass conservation. The effects of the heat release rate and press-in ventilation velocity (({u}_{p})) on the smoke stratification characteristics, longitudinal velocity, and mass flow rate are studied using numerical simulation. The results show that the smoke stratification stability on the downstream side is divided into stage I, critical moment A, and stage II. On this basis, the concept of subcritical velocity ((:{u}_{sub})) is proposed. Stage I: ({u}_{p}) < ({u}_{sub}), the flow directions of smoke and induced air are opposite, and the smoke stratification is stable. Critical moment A: (:{u}_{p}) = ({u}_{sub}), the lower airflow slowly flows and approaches stagnation, and the smoke stratification transits from a relatively stable state to an unstable state. Stage II: ({u}_{p}) > ({u}_{sub}), the flow directions of smoke and excess press-in ventilation are consistent, and the smoke stratification is destroyed. The prediction models of the subcritical and critical velocities are established. The critical velocity is twice the subcritical velocity in the same fire scenario. The results can provide a theoretical foundation for the application of press-in ventilation in tunnel fires during construction.                

In developing countries like Bangladesh, fire prevention and mitigation initiatives are limited due to insufficient information about fire risk and related perceptions. However, the perception of fire risk at the municipality household level in coastal Bangladesh has yet to be studied in existing literature. This study aimed thereby to assess the perception of fire risk at the household level and investigate the influence of demographic and economic factors on the perception of fire risk in the Patuakhali municipality of southern Bangladesh. A total of 166 randomly selected households were contacted for an extensive interview. We found a medium level of fire risk perception in the study area based on the combined fire risk perception index score. Spatially, this perception may vary depending on socio-economic characteristics. The ANOVA test results show that out of 14 variables, about 57.1% are significantly associated with the educational status of the respondents, and about 35.7% are associated with family income conditions. The findings indicated that individuals with higher years of education and households with higher monthly income exhibited a higher perception of fire risk, and the perception is significant at 0.01 level. In addition, this perception was moderate to high in most of the wards (7 out of 9) in the Patuakhali municipality. Our findings have important implications for fire hazard education and management in urban areas, especially neighbourhoods with low and medium perceived risk.

This study investigates the combined effects of corrosion and fire on the structural performance of reinforced geopolymer concrete (GPC) columns. Four full-scale specimens were exposed to accelerated corrosion and ISO 834-standard fire conditions for 60–90 min. Key structural parameters—including axial load capacity, stiffness, ductility, toughness, and energy absorption—were evaluated to assess post-fire performance. Results show that both corrosion and fire independently reduce strength and stiffness, but their combined impact leads to severe degradation. The most heavily damaged specimens exhibited up to 79% loss in ultimate load, 64% loss in stiffness and over 90% reduction in energy absorption capacity. While some increases in ductility were observed under combined exposure, they were accompanied by substantial losses in load-bearing capacity. These severe reductions suggest that standard fire resistance assessments, when applied without considering prior corrosion, may significantly overestimate post-fire capacity, underscoring the need for corrosion deterioration models in structural fire design.

Using timber as a structural material in buildings is promising in reducing the carbon footprint of construction, although fire safety has been a long-standing challenge prohibiting its wider use. The current design practice usually complies with Eurocode 5, but it is largely prescribed only for standard fire scenario. While investigating the fire behavior in real compartments containing timber members, the fire action imposed on the surface of timber members can be hardly represented by the standard fire curve. Therefore, modelling the heat transfer of timber sections in these real fire scenarios requires adequate numerical models. In this paper, the heat transfer model equipped with temperature-variant thermal properties of timber as well as a heat generation model addressing timber combustion effect, has been developed and implemented in the open-source simulation platform OpenSees for fire. Advancing from the existing heat transfer models, the present model has been validated against test results of timber sections subjected to the prescribed non-standard fire actions supported by the e-controlled radiant panel system. The modelling results have shown good performance in predicting the temperature evolution at various depths of the timber sections subjected to non-standard heating conditions.

This study presents a systematic evaluation of fire suppression strategies for lithium-ion Battery Energy Storage Systems (BESS), specifically examining thermal runaway propagation in small domestic system (8 kWh). Five distinct suppression methods were evaluated: water mist, encapsulator agent (water mist with proprietary encapsulator), carbonate agent (water mist with ammonium bicarbonate), mixed agent (containing boron compounds and surfactants), and liquid nitrogen. Performed experiments revealed significant differences between suppression methods. Water mist and encapsulator agents demonstrated better performance, extending propagation delay times by 179% and 167%, respectively, compared to control tests without a suppression method. Registered maximum temperatures varied across methods from 780° to 890 °C. However, none of the tested methods prevented thermal runaway propagation entirely and were able to save the system from being destroyed. Critical safety concerns emerged regarding vapour cloud production, which correlated strongly with cooling effectiveness (r = 0.87) but increased explosion risks. Statistical analysis confirmed significant method-dependent differences (p < 0.001), with water mist and encapsulator agents reducing thermal runaway hazard ratios by over 70%. These results indicate that current suppression technologies can delay but not prevent thermal runaway propagation. Findings emphasize the need for integrated approaches combining efficient cooling with vapour management strategies, particularly for residential BESS installations.