Search Results (136)

Historical seismic events have repeatedly highlighted the susceptibility of above-ground liquid storage steel tanks, underscoring the critical need for their proper design to minimize potential damage due to seismic forces. A significant failure mechanism in these structures, which play essential roles in the extraction and distribution of various raw or refined materials—many of which are flammable or environmentally hazardous—is the dynamic buckling of the tank walls. This study introduces a numerical framework designed to assess the earthquake-induced hydrodynamic pressures exerted on the walls of cylindrical steel tanks. These pressures result from the inertial forces generated during seismic activity. The computational framework incorporates material and geometric nonlinearities and models the tanks using four-node shell elements with two-point integration, specifically Belytschko shell elements. The Arbitrary Lagrangian–Eulerian (ALE) method is employed to accommodate substantial structural and fluid deformations, enabling a full simulation of fluid–structure interaction through highly nonlinear algorithms. Experimental test data are utilized to validate the proposed modeling approach, particularly in replicating sloshing phenomena and identifying stress concentrations that may lead to wall buckling. The study further presents results from a parametric analysis that varies the height-to-radius and radius-to-thickness ratios of a typical anchored flat-bottomed tank, examining the seismic performance of this common storage system. These results provide insights into the relationship between tank properties and mechanical behavior under dynamic loading conditions. Full article

Due to the flammable and explosive nature of explosives, there are significant potential hazards and risks during transportation. During the operation of explosive transport vehicles, there are often situations where the vehicles around them approach or change lanes abnormally, resulting in insufficient avoidance and collision, leading to serious consequences such as explosions and fires. Therefore, in response to the above issues, this article has developed an explosive transport vehicle driving warning system based on object detection algorithms. Consumer-level cameras are flexibly arranged around the vehicle body to monitor surrounding vehicles. Using the YOLOv4 object detection algorithm to identify and distance surrounding vehicles, using a game theory-based cellular automaton model to simulate the actual operation of vehicles, simulating the driver’s decision-making behavior when encountering other vehicles approaching or changing lanes abnormally during actual driving. The cellular automaton model was used to simulate two scenarios of explosive transport vehicles equipped with and without warning systems. The results show that when explosive transport vehicles encounter the above-mentioned dangerous situations, the warning system can timely issue warnings, remind drivers to make decisions, avoid risks, ensure the safety of vehicle operation, and verify the effectiveness of the warning system. Full article

A faulty voltage measurement can lead to the overcharging of a Li-Ion cell, resulting in gas formation and heating inside the cell, which can trigger thermal runaway. To mitigate this risk, cylindrical cells are equipped with a Current Interrupt Device (CID), which functions as a pressure relief valve, disconnecting the electrical circuit within the cell when internal pressure rises. However, this disconnection causes the cell to suddenly become highly resistant, posing a significant issue in series-connected cells. In such configurations, a portion or even the entire system voltage may drop across the disconnected cell, substantially increasing the likelihood of an electric arc. This arc could ignite any escaping flammable gases, leading to catastrophic failures. In a series of tests conducted on three different cell chemistries—NMC (Nickel Manganese Cobalt), NCA (Nickel Cobalt Aluminum), and LFP (Lithium Iron Phosphate)—it was found that the safe operation of the CID cannot be guaranteed for system voltages exceeding 120 V. Although comparative tests at double the nominal cell voltage did not exhibit the same behavior, these findings suggest that current safety standards, which recommend testing at double the nominal voltage, may not adequately address the risks involved. The tests further revealed that series connections of cells with CIDs are inherently dangerous, as, in the worst-case scenario, the entire system voltage can be concentrated across a single cell, leading to potential system failure. Full article

Brominated flame retardants (BFRs) are synthetic chemicals widely used to reduce the flammability of consumer products, including electronics, textiles, and furniture. Despite their effectiveness in fire prevention, BFRs pose significant environmental and health risks due to their persistence, bioaccumulation, and potential toxicity. This review provides a comprehensive examination of BFRs, focusing on recent advancements in analytical methods for their detection and quantification in environmental and biological samples. The study explored the physicochemical properties that influence BFR distribution and transport in various matrices, including soil, water, air, sediments, and biota. The review also summarizes current knowledge on the occurrence and environmental fate of BFRs, highlighting their mobility and long-range transport. Furthermore, the study discusses the health risks associated with BFR exposure, emphasizing their endocrine-disrupting effects and impact on reproductive and neurological functions. By integrating findings from recent studies, this review aims to enhance the understanding of BFR behavior and inform regulatory strategies to mitigate their adverse effects on human health and the environment. Full article

With the widespread application of lithium-ion batteries (LIBs) energy storage stations in high-altitude areas, the impact of ambient pressure on battery thermal runaway (TR) behavior and venting flow characteristics have aroused wide research attention. This paper conducts a lateral heating experiment on 280 Ah lithium iron phosphate batteries (LFPs) and proposes a method for testing battery internal pressure using an embedded pressure sensor. This paper analyzes the battery characteristic temperature, internal pressure, chamber pressure, and gas components under different chamber pressures. The experiment is carried out in a N₂ atmosphere using a 1000 L insulated chamber. At 40 kPa, the battery experiences two instances of venting, with a corresponding peak in temperature on the battery’s side of 136.3 °C and 302.8 °C, and gas generation rates of 0.14 mol/s and 0.09 mol/s, respectively. The research results indicate that changes in chamber pressure significantly affect the center temperature of the battery side (T_s), the center temperature of the chamber (T_c), the opening time of the safety valve (t_open), the triggering time of TR (t_TR), the time difference (Δt), venting velocity, gas composition, and flammable limits. However, the internal pressure and gas content of the battery are apparently unaffected. Considering the TR characteristics mentioned above, a safety assessment method is proposed to evaluate the TR behavior and gas hazard of the battery. The results indicate that the risk at 40 kPa is much higher than the other three chamber pressures. This study provides theoretical references for the safe use and early warning of energy storage LIBs in high-altitude areas. Full article

The growing requirements regarding the safety of using polymers and their composites are related to the emergence of more effective, sustainable, and hazardous-limited fire retardants (FRs). Significant amounts of FRs are usually required to effectively affect a polymer’s burning behavior, while the knowledge of their recycling potential is still insufficient. At the same time, concerns are related not only to the reduced effectiveness of flame retardancy but also, above all, to the potential deterioration of mechanical properties caused by the degradation of temperature-affected additives under processing conditions. This study describes the impact of the four-time reprocessing of bio-based polyamide 11 (PA11) modified with an intumescent flame-retardant (IFR) system composed of ammonium polyphosphate (APP), melamine cyanurate (MC), and pentaerythritol (PER) and its composites containing additional short basalt fibers (BFs). Composites manufactured via twin-screw extrusion were subjected to four reprocessing cycles using injection molding. A comprehensive analysis of their structural, mechanical, and fire behavior changes in each cycle was conducted. The obtained results confirmed the safety of using the proposed fire-retarded polyamide and its composites while reprocessing under the recommended process parameters without the risk of significant changes in the structure. The partial increase in flammability of reprocessed PA-based materials caused mainly by polymer degradation has been described. Full article

After the period of halogenated compounds, the period of nano-structured systems, and that of phosphorus (and nitrogen)-based additives (still in progress), following the increasingly demanding circular economy concept, about ten years ago the textile flame retardant world started experiencing the design and exploitation of bio-sourced products. Indeed, since the demonstration of the potential of such bio(macro)molecules as whey proteins, milk proteins (i.e., caseins), and nucleic acids as effective flame retardants, both natural and synthetic fibers and fabrics can take advantage of the availability of several low-environmental impact/“green” compounds, often recovered from wastes or by-products, which contain all the elements that typically compose standard flame-retardant recipes. The so-treated textiles often exhibit flame-retardant features that are similar to those provided by conventional fireproof treatments. Further, the possibility of using the same deposition techniques already available in the textile industry makes these products very appealing, considering that the application methods usually do not require hazardous or toxic chemicals. This review aims to present an overview of the development of bio-sourced flame retardants, focusing attention on the latest research outcomes, and finally discussing some current challenging issues related to their efficient application, paving the way toward further future implementations. Full article

Liquid hydrogen storage is an important way of hydrogen storage and transportation, which greatly improves the storage and transportation efficiency due to the high energy density but at the same time brings new safety hazards. In this study, the liquid hydrogen leakage in the storage area of a hydrogen production station is numerically simulated. The effects of ambient wind direction, wind speed, leakage mass flow rate, and the mass fraction of gas phase at the leakage port on the diffusion behavior of the liquid hydrogen leakage were investigated. The results show that the ambient wind direction directly determines the direction of liquid hydrogen leakage diffusion. The wind speed significantly affects the diffusion distance. When the wind speed is 6 m/s, the diffusion distance of the flammable hydrogen cloud reaches 40.08 m, which is 2.63 times that under windless conditions. The liquid hydrogen leakage mass flow rate and the mass fraction of the gas phase have a greater effect on the volume of the flammable hydrogen cloud. As the leakage mass flow rate increased from 5.15 kg/s to 10 kg/s, the flammable hydrogen cloud volume increased from 5734.31 m³ to 10,305.5 m³. The installation of a barrier wall in front of the leakage port can limit the horizontal diffusion of the flammable hydrogen cloud, elevate the diffusion height, and effectively reduce the volume of the flammable hydrogen cloud. This study can provide theoretical support for the construction and operation of hydrogen production stations. Full article

Over the past few decades, polymer composites have received significant interest and become protagonists due to their enhanced properties and wide range of applications. Herein, we examined the impact of filler and flame retardants in hemp seed oil-based rigid polyurethane foam (RPUF) composites’ performance. Firstly, the hemp seed oil (HSO) was converted to a corresponding epoxy analog, followed by a ring-opening reaction to synthesize hemp bio-polyols. The hemp polyol was then reacted with diisocyanate in the presence of commercial polyols and other foaming components to produce RPUF in a single step. In addition, different fillers like microcrystalline cellulose, alkaline lignin, titanium dioxide, and melamine (as a flame retardant) were used in different wt.% ratios to fabricate composite foam. The mechanical characteristics, thermal degradation behavior, cellular morphology, apparent density, flammability, and closed-cell contents of the generated composite foams were examined. An initial screening of different fillers revealed that microcrystalline cellulose significantly improves the mechanical strength up to 318 kPa. The effect of melamine as a flame retardant in composite foam was also examined, which shows the highest compression strength of 447 kPa. Significantly better anti-flaming qualities than those of neat foam based on HSO have been reflected using 22.15 wt.% of melamine, with the lowest burning time of 4.1 s and weight loss of 1.88 wt.%. All the composite foams showed about 90% closed-cell content. The present work illustrates the assembly of a filler-based polyurethane foam composite with anti-flaming properties from bio-based feedstocks with high-performance applications. Full article

Nowadays, nanotechnology represents a well-established approach, suitable for designing, producing, and applying materials to a broad range of advanced sectors. In this context, the use of well-suited “nano” approaches accounted for a big step forward in conferring optimized flame-retardant features to such a cellulosic textile material as cotton, considering its high ease of flammability, yearly production, and extended use. Being a surface-localized phenomenon, the flammability of cotton can be quite simply and effectively controlled by tailoring its surface through the deposition of nano-objects, capable of slowing down the heat and mass transfer from and to the textile surroundings, which accounts for flame fueling and possibly interacting with the propagating radicals in the gas phase. In this context, the layer-by-layer (LbL) approach has definitively demonstrated its reliability and effectiveness in providing cotton with enhanced flame-retardant features, through the formation of fully inorganic or hybrid organic/inorganic nanostructured assemblies on the fabric surface. Therefore, the present work aims to summarize the current state of the art related to the use of nanostructured LbL architectures for cotton flame retardancy, offering an overview of the latest research outcomes that often highlight the multifunctional character of the deposited assemblies and discussing the current limitations and some perspectives. Full article

Cooling processes are responsible for a significant portion (20%) of global energy consumption and raise environmental concerns such as ozone depletion, the greenhouse effect, and high energy use. This study investigates the potential of R152a, a refrigerant with low global warming potential (GWP), as a more sustainable alternative. The performance, safety, and operational efficiency of R152a were evaluated under various conditions. Although R152a offers high performance and low GWP, its flammability necessitates caution, especially in certain mixtures. A 12-pass tube-type heat exchanger model was simulated using computational fluid dynamics (CFD) to analyze the fluid behavior within the exchanger. The pressure, density, dynamic pressure, Prandtl number, total pressure, and temperature distributions for both R152a and H₂O (water) were visualized using contour plots. The simulations comprehensively examined the fluid behavior inside and outside the heat exchanger. The results revealed the influence of the temperature on the internal dynamic pressure and density of R152a. Compared with R134a, R152a demonstrated superior performance but a lower coefficient of performance (COP) than R32. Studies also suggest that R152a exhibits lower irreversibility in Organic Rankine Cycle (ORC) systems than R245fa. These findings suggest that R152a holds promise for future refrigeration systems, as supported by existing research on its performance and compatibility. One study focused on optimizing the heat exchanger performance by maximizing the heat capacity and minimizing the pressure drop. This study employed a parallel-flow heat exchanger with R152a as the coolant for the hot process water. The temperature changes, pressure drops, and resulting energy efficiency and thermal performance of both fluids were analyzed. The results highlight the distinct energy efficiencies and thermal performance of the employed fluids. Full article

This research study focused on the effect of adding boric acid to epoxy resin in order to obtain a composite material with improved properties and performance. To this end, a fine powder of boric acid (H₃BO₃) was introduced into epoxy resin in different amounts, i.e., 0.5 g, 1.0 g, and 1.5 g. As the matrix of the epoxy composites, styrene-modified epoxy resin based on bisphenol A (BPA) (Epidian 53) was used. It was cross-linked with two types of curing agents, i.e., an amine (ET) and a polyamide (PAC). The mechanical properties of the obtained epoxy composites (in terms of compressive strength, compressive modulus, and compressive strain) were determined at room temperature in order to assess the effect of the addition of boron acid and of the type of curing agent employed to cure the epoxy on these characteristics. Calorimetric measurements were made to highlight any changes in the glass transition temperature (Tg) as a result of the addition of boric acid to epoxy resin. Finally, flammability tests were performed on both Epidian 53/PAC and Epidian 53/ET epoxy composites to analyze their fire behavior and consequently establish the effectiveness of the selected additive as a flame retardant. Full article

This study explores the fire behavior of wood–glass and jute–glass hybrid laminates, with a focus on the influence of jute and wood veneers as new materials for composite production. Five-layer hybrid laminates were manufactured using the vacuum infusion process (VIP). Combustion and carbonization performances were assessed using a cone calorimeter based on the ISO 5660 method. This study evaluates flammability through key parameters including ignition time, heat release rate, and smoke production. The results indicated that the ignition time was significantly longer (ca. 64 s) for the glass–jute laminate (GJGJG), compared to the wood–glass laminate (WGWGW) (ca. 53 s). The heat release rate of laminates containing organic components was higher than the sample composed only of glass mat (G5) but their rates were all lower than the polyester reference resin. WGWGW, compared to the GJGJG sample, was able to produce a good-quality protective shield and, therefore, postpone the occurrence of the heat release peak. In this way, the fire growth rate index (FIGRA) best performance was accomplished by the WGWGW sample (2.7 ± 0.3 kW/m² × s), which was even better than that of the G5 sample. The total-smoke-released value was highest for polyester, 7361 ± 839 m²/m², followed by WGWGW, 2873 ± 188 m²/m², and J5, 2484 ± 216 m²/m². Among the hybrid laminates, the best performance was obtained by GJGJG, 1860 ± 49 m²/m², but compared to the G5 laminates, it was only ~36% higher. The specific extinction area (SEA) is a smoke parameter related to the mass of the samples; the best result was obtained by WGWGW with 697 ± 31 m²/kg. Finally, the neat polyester and all laminates achieved UL 94HB classification, with firing rates below 40 mm/min. Full article

Microcellulose materials are increasingly considered multifunctional candidates for emerging energy applications. Microcellulose fibers (MCF) are a kind of bio-based reinforcement in composites, and their hydrophilic character hinders their wide application in industry. Thus, in the present work, MCF was hybrid-modified by amino silicone oil-phosphorylated to fabricate hydrophobic, thermal stability, and flame-retardant microcellulose fibers for potential application in vehicle engineering. The results showed that the amino silicone oil-phosphorylated (ASOP) hybrid modification could transform the surface property of microcellulose from hydrophilic to hydrophobic and improve the compatibility between MCF and resin matrix. Meanwhile, the ASOP treatment led to the formation of an amino silicone oil film layer on the surface of the microcellulose, which improved the thermal stability of the MCF. Furthermore, the ASOP hybrid modification microcellulose fibers paper (100% microcellulose fibers paper) was transformed from flammable to flame-retardant and showed self-extinguishing behavior after burning under flame for 2 s. The flame-retardant mechanism was attributed to the formation of the char layer in the condensed phase and the production of non-combustible gases in the gaseous phase. Full article

The present work proposes to investigate the effect of an ultrahigh molecular weight silicone rubber (UHMW-SR) and two ethylene methyl acrylate copolymers (EMA) with different methyl acrylate (MA) content on the mechanical and fire performance of a fireproof acrylonitrile butadiene styrene copolymer (ABS) composite, with an optimum amount of ammonium polyphosphate (APP) and aluminum diethyl phosphinate (AlPi). ABS formulations with a global flame retardant weight content of 20 wt.% (ABS P) were melt-compounded, with and without EMA and UHMW-SR, in a Brabender mixer. During this batch process, ABS P formulations with UHMW-SR and/or EMA registered lower torque values than those of ABS P. By means of scanning electron microscopy (SEM), it was possible to observe that all ABS composites exhibited a homogenous structure without phase separation or particle agglomeration. Slightly improved interfacial interaction between the well-dispersed flame-retardant particles in the presence of EMA and/or UHMW-SR was also noticed. Furthermore, synergies in mechanical properties by adding both EMA and UHMW-SR into ABS P were ascertained. An enhancement of molecular mobility that contributed to the softening of ABS P was observed under dynamic mechanical thermal analysis (DMTA). An improvement of its flexibility, ductility and toughness were also registered under three-point-bending trials, and even more remarkable synergies were noticed in Charpy notched impact strength. Particularly, a 212% increase was achieved when 5 wt.% of EMA with 29 wt.% of MA and 2 wt.% of UHMW-SR in ABS P (ABS E29 S P) were added. Thermogravimetric analysis (TGA) showed that the presence of EMA copolymers in ABS P formulations did not interfere with its thermal decomposition, whereas UHMW-SR presence decreased its thermal stability at the beginning of the decomposition. Although the addition of EMA or UHMW-SR, as well as the combination of both in ABS P increased the pHRR in cone calorimetry, UL 94 V-0 classification was maintained for all flame-retarded ABS composites. In addition, through SEM analysis of cone calorimetry sample residue, a more cohesive surface char layer, with Si-O-C network formation confirmed by Fourier transform infrared (FTIR), was shown in ABS P formulations with UHMW-SR. Full article