Fire Safety Journal最新文献

In this article domestic fire response and fire injury was examined using a Bayesian analysis approach. A Bayesian model was developed to estimate the probability of non-fatal fire injury associated with a given fire response (escape, return to fire, fight the fire) under given circumstances of non-fatal fire injury (age band, gender, smoke alarm presence, type of domestic fire). The Bayesian model was developed using non-fatal fire injury data recorded by Merseyside Fire and Rescue Service between 2011 and 2022. Overall, more domestic fire injuries relating to attempting to fight the fire occurred in properties with a smoke detector (82 % of attempting to fight the fire injuries) compared to properties without a smoke detector (18 % of attempting to fight the fire injuries). Similarly, fire injuries sustained returning to the fire mainly occurred in properties with a smoke detector (75 % of returning to fire injuries) as opposed to properties without a smoke detector (25 % of returning to fire injuries).

The aerial drop characteristic of mass firefighting units has a significant influence on the effectiveness of aerial firefighting. In order to accurately describe the aerial drop characteristic of mass firefighting units, a numerical model covering the fundamental stages of the whole operation process was developed in the present study. In the model, mass firefighting units' filling and discharging processes are simulated by the discrete element method; the falling process is simulated by aerodynamic analysis, and the ground pattern characteristics are obtained. The model validation shows that, the numerical result agrees well with the experimental result with a maximum deviation of 14 %. The initial velocity distribution characteristic remains constant with varying filling amounts, and the mass fire firefighting units' initial velocities at different times follow a special normal distribution; the standard deviation of the initial velocities’ distribution primarily determines the width of mass firefighting units' ground pattern, while initial velocity and filling amount primarily determine the length of the ground pattern; the maximum coverage level is about 10 L/m².

The synthesis and characterization of a modified zirconium phosphate (MZrP) nano-inhibitor for spontaneous coal combustion inhibition were explored through isooctylamine intercalation. Using oxidation experiment, FTIR and SEM, the variation rules of the characteristic parameters of the different coal samples were investigated. It was observed that MZrP exhibited enhanced dispersion within the coal matrix post-intercalation modification. As the MZrP concentration increased, there was a notable decrease in oxygen consumption rate, gas production concentration, and active group content in the coal, alongside a significant increase in apparent activation energy and inhibition efficacy. This enhanced inhibition is attributed to two primary mechanisms. Firstly, the hydrophilic nature of MZrP allows for its uniform distribution on the coal surface and within internal pores, creating a dense carbonized layer. This layer effectively retains moisture and isolates oxygen, enhancing physical inhibition. Secondly, MZrP inhibitor is thermally decomposed into phosphoric acid and its phosphoric acid derivatives, which can effectively capture the H- and -OH in the coal, and strengthens the inactivation of its reactive free radicals. The optimal inhibition was observed in coal samples treated with 6 wt% MZrP, exhibiting an average inhibition rate of 62.2 %, coupled with the lowest rates of gas production and oxygen consumption.

There have been efforts to predict the occurrence of flashover. Due to its sudden development and the difficulty in discerning warning signs during the induction phase, the approach to flashover prediction is still under investigation. This research tests a new approach for detecting flashover events within a compartment through single-signal processing of the heat release rate (HRR). A set of ordinary differential equations aligned with a two-zone model are formulated and transformed into stochastic differential equations, subsequently solved through a numerical method. Based on the noisy HRR readings, a dynamical marker is constructed as a product of two quantities: the smoothed HRR and the standard deviation of the noise component. The dynamical marker was found to increase prior to a rise in the HRR signal on its own, confirming its superiority as a sign of flashover detection. To assess the practical applicability of the dynamical marker, we computed it to detect flashover incidents using HRR obtained from an FDS simulation and the fire calorimetry database provided by NIST; the dynamical marker exhibited a significant rise before the transition to flashover, confirming its potential as an early warning signal.

This article assesses the capability of the PAH-based soot model developed by the authors and validated in ethylene non-premixed flames to predict soot production in flames fueled with gasoline surrogates. The soot model was coupled to a flamelet model and the Rank-Correlated Full-Spectrum k model to simulate laminar coflow nitrogen-diluted methane/air diffusion flames doped with n-heptane/toluene and iso-octane/toluene mixtures. Consistent with our previous studies, the simulation was conducted using the Kaust Mechanism 1, pyrene as soot precursor, and the same set of model parameters. The model reproduced reasonably-well the peak soot volume fraction. However, the soot production onset was predicted much earlier than measurements owing to the early formation of pyrene induced by the presence of toluene. These discrepancies can be partially corrected by selecting a larger PAH than pyrene with a similar level of concentrations as soot precursor. For the present mechanism, anthanthrene was found to be the best candidate. Model results show that different mechanisms dominate the soot mass growth in ethylene and gasoline surrogate flames. While the HACA is more important in the former, PAH condensation largely prevails in the latter. This suggests that ethylene may be not the most relevant reference fuel for developing semi-empirical soot models for fires. Further investigations are required to confirm this conjecture.

To enhance intelligent prevention and control of methane/coal dust explosions in coal mines, the active explosion suppressor was developed. Methane/coal dust explosion suppression experiments were carried out in an 896-m mining tunnel. The suppression mechanism of NH₄H₂PO₄ powder during methane/coal dust explosions was elucidated. The results indicated that the device effectively prevented flame propagation within a 40 m radius by propelling NH₄H₂PO₄ powder using high-pressure nitrogen. There was a significant reduction in the intensity and destructiveness of the overpressure, with a maximum decrease of 61.43 %. The phosphorus-containing material produced by NH₄H₂PO₄ consumed free radicals through catalytic cycles of HOPO ⇔ PO₂ and HOPO ⇔ HPO₃⇔PO(OH)₂, weakening and interrupting the reactions, and suppressing flame development. NH₄H₂PO₄ reduced peak concentrations of CO and NO₂. Guidelines for explosion suppression of CH₄/coal dust explosions in large mining tunnel were presented. The findings provide technical and theoretical support for the prevention and control of methane/coal dust explosions in coal mines.

This study explored the effects of oil phase n-alkane on the emulsion properties and fire suppression ability of n-alkane/water microemulsions containing ferrocene. We used n-pentane, n-heptane, and n-decane as the oil-phase n-alkanes; the microemulsions were prepared according to the agent-in-water technique using Noigen TDS-80 as a surfactant. Emulsion stability testing and dynamic light scattering measurements demonstrated that the n-decane/water systems were thermodynamically unstable macroemulsions, whereas the n-pentane/water and n-heptane/water systems were thermodynamically stable microemulsions. Fire suppression trials proved that (i) most of the n-pentane/water and n-heptane/water microemulsions had an extinguishing probability of 1.0, (ii) their suppression ability was ranked as follows: the n-pentane/water microemulsions > the n-heptane/water microemulsions ≫ the decane/water macroemulsions; and (iii) the optimum concentration of ferrocene was 100 ppm. The suppression ability of the microemulsions is attributed to the radical scavenging efficiency in flames and the ease with which ferrocene in the microemulsions is released. The findings of this research suggest that the use of an n-alkane with a low boiling point significantly increases the suppression ability of a microemulsion. An outstanding advantage of microemulsions is that even highly lipophilic substances can be employed as additives to water mists, suggesting that the microemulsificaiton approach widens water mist additive options.

Spotting ignition involves dynamic interaction between fuel bed and hot particles, but the scientific understanding of the ignition by a fast-moving hot particle is still limited. Herein, a hot steel particle with various horizontal velocities, temperatures, and sizes is shot to ignite vertically oriented low-density expandable polystyrene foam. A high-speed particle can directly get embedded into the foam to achieve flash-point, fire-point, or no ignition, while a low-speed particle bounces away from the foam without ignition. Results show that for a particle of 1150 °C, its minimum velocity for embedding is 12.00 m/s. Such a critical velocity for hot-particle embedded or ignition slightly decreases as particle temperature increases. Minimum ignition temperature of these high-speed particles is 200 °C higher than that of near-static or with a low free-fall velocity, due to the shorter residence time and insufficient to produce a flammable mixture. Moreover, when the particle is neither too slow to bounce away nor too fast to get embedded, it will be partially embedded on the sample surface to burnout the fuel, posing the biggest fire hazard. It deepens our knowledge of the complex interaction between hot moving particles and insulation foam to reduce spotting fire risk for building façade.