Fire and Materials最新文献

This paper investigated a slag composite high-efficiency fire extinguishing material to recycle power plant slag waste and apply it to prevent and control spontaneous coal combustion fires. The composite uses power plant slag as a base material, sodium carboxymethyl cellulose (CMC) as a polymer, and AlCit solution formulated with polyaluminum chloride and citric acid as a cross-linking agent. X-ray diffractometer (XRD) and scanning electron microscope (SEM) were used to analyze slag composition and morphology. Experiments investigated the effects of composites on coal microactive groups, rheological properties, and inhibition characteristics against coal spontaneous combustion. Analyses showed composites could effectively reduce activities of aromatic hydrocarbons, OH groups, aliphatic hydrocarbons, and oxygenated functional groups in coal samples, with prominent inhibition of oxygenated functional groups and OH reactive groups. Experimental results showed composite samples exhibited a shear thinning phenomenon of yield-pseudoplastic fluid, and viscosity gradually increased with time. Viscosity increase rates of samples were 9.20%, 17.35%, and 30.75% for each 5-min interval. Composites could delay the time when coal samples enter the rapid oxidation stage, and the crossing point temperature of coal samples increased from 152°C to 180°C. Composites had an inhibitory effect on coal oxygen reaction, and in programmed warming experiments, the temperature at which the residual mass of coal samples began to increase increased from 179°C to 202°C. The slag composite high-efficiency fire extinguishing material provides reference value for the combination of slag waste and mine fire extinguishing technology.

The need for flame-retardant materials with good mechanical properties is rapidly growing across numerous sectors, such as construction, automobile, and aerospace industries. In this research, a comprehensive study has been conducted focusing on flame retardant and mechanical characteristics of distinct resin-based fiber-reinforced composites. Glass and sisal fiber-based woven fabrics have been used as reinforcements in four different types of resin matrices, such as epoxy, vinyl ester, unsaturated polyester, and phenolic resins. The developed composites were systematically evaluated for their flame-retardant properties using limiting oxygen index (LOI), vertical flammability, and cone calorimetry tests, with a focus on assessing the inherent flame resistance of the resins without the incorporation of flame-retardant additives. In parallel, the mechanical behavior of the composites was examined through tensile and flexural testing to determine the combined effects of fiber type and resin matrix. The findings demonstrate that different resin-based composites provide an optimal balance between flame retardancy and mechanical strength, making them suitable for applications requiring both fire safety and structural reliability. The insights gained from this research contribute to the development of new composite materials with enhanced fire performance without compromising mechanical performance.

The complexity of urban tunnel structure increases the risk of tunnel fire, and the air curtain system plays an important role in controlling the spread of fire smoke and ensuring the safety of personnel. Based on theoretical analysis and tunnel model experiments, the isolation effect of different air curtain jet conditions on high-temperature fire smoke in bifurcated tunnel was studied. The results show that the air curtain system can effectively isolate the high-temperature smoke. For different firepower, compared to angle and thickness, wind speed has the best control effect on high-temperature smoke. The control effect of air curtain thickness takes second place. The effect of angle change is the least obvious. Meanwhile, based on the analysis of experimental results, it was found that when the air curtain parameters are selected as wind speed of 2.5 m/s, angle of 15°, and thickness of 0.16 m, the air curtain system has better smoke prevention efficiency. Finally, dimensionless analysis yielded a power law equation relating upstream temperature rise, firepower, and wind speed. This supports theoretically analyzing the air curtain's smoke prevention effect.

Understanding fire behavior during critical stages such as flashover and fully developed fire is crucial for firefighter training and safety. This empirical research investigates the influence of fuel–air ratio variations on the occurrence of flashover, the formation of fully developed fire stages, and the temperature dynamics of the upper gas layer. Wooden pallets are utilized as the fuel source in experiments conducted under controlled ventilation conditions. Five different fuel–air ratios ranging from 0.2 to 1.2 are examined, revealing significant insights. The findings of this study highlight the importance of fuel–air ratio adjustments in shaping fire behavior within controlled environments, such as firefighter training compartments. As a result, increasing the fuel-air ratio substantially extends the fully developed fire stage's duration. Moreover, the experimental findings indicate that a minimum fuel-to-air ratio of 0.545 is necessary to initiate a flashover, and fuel-air ratio escalation accelerates the flashover onset. Fuel–air ratios of 0.73 and higher caused the upper layer of gas in the chamber to reach a temperature exceeding 800°C for more than 180 s. These insights are instrumental in enhancing our understanding of fire dynamics and devising more effective firefighting strategies and safety protocols.

A series of numerical simulations and small-scale experiments have been conducted to study the smoke diffusion and maximum ceiling gas temperature in an inclined tunnel with the upper or lower portal sealed. A total of 60 simulation cases and 4 experimental tests were conducted, and different sealing conditions, heat release rates, and tunnel slopes were taken as the main variables. The results show that the sealing condition and tunnel slope have a significant impact on the smoke diffusion and flame shape. When the lower portal is sealed, smoke moves to the opening along the tunnel ceiling, and there is an obvious shear phenomenon between the smoke layer and the cold air layer. When the upper portal is sealed, the smoke layer interface in the downhill direction is almost parallel to the horizontal line, and a larger slope means a longer time taken to spill out of the tunnel. In horizontal tunnels, the maximum ceiling temperature in the tunnel with two portals opened is larger than that in the one-portal-sealed tunnel. Tunnel slope has little effect on the maximum temperature rise for the inclined tunnel with the lower portal sealed. However, in the tunnel with the upper portal sealed, the maximum temperature rise increases with the tunnel slope, and the growth is relatively linear. For inclined tunnels, a comprehensive empirical formula is finally established to estimate the maximum ceiling temperature, taking sealing condition, heat release rate, and tunnel slope into consideration.

Ship fires pose significant threats to maritime safety. This study employs advanced text mining techniques alongside the K-means algorithm to develop a risk structure for ship fires, aiming to identify key risks and fire scenarios. We collected detailed fire investigation reports from authoritative sources, creating a database of 160 incidents over the past 20 years to analyze accident patterns. To enhance traditional text mining, we extracted 260 risk descriptors using specialized dictionaries, calculating their correlations. The improved K-means algorithm, utilizing cosine distance, clustered over 1000 related word combinations, revealing 13 key risks and 42 fire scenarios. From these findings, a risk structure was established through critical importance calculations. Results indicate that damage to flammable liquid tanks or pipes and improper storage of flammable solids are critical risks, elevating fire probability by over 15%. Risks like insulation failure and electrical short circuits showed critical importance values between 0.06 and 0.07. Notably, fire scenarios involving flammable oil leaks and electrical failures are interconnected, with the combination of flammable liquid leaks and insulation failure representing the most hazardous scenario, increasing fire probability by about 30%. This study introduces a data-driven approach to identify potential risks and fire scenarios, contributing practically to risk prevention and management in maritime accidents.