Total Burning Time Research Articles

Experimental and Numerical Studies on the Fire Performance of Thin Sustainable Wood-Based Laminated Veneers

Wood and wood-based products are abundantly used, especially in structural applications, due to the impetus for sustainable development. The present work helps highlight the fire performance of plywood, one of the most used wood-based laminated structural components, under three different heat fluxes of 35 kW/m2, 50 kW/m2, and 65 kW/m2. The effects on the various fire reaction properties, namely, time to ignition, heat release rate, peak heat release rate, time to peak heat release rate, time to flameout, total burn time, and mass loss, were observed and reported. The times to ignition (42.2% and 35.4%), peak heat release rate (27.7% and 18.9%), flameout (22.2% and 28.6%), burn time (10.6% and 16.1%), and residual mass (25% and 53.3%) were reduced with the increase in heat flux from 35 kW/m2 to 65 kW/m2, respectively, whereas the peak heat release (21.7% and 2.4%) and ignition temperature (6.5% and 6.6%) were observed to increase. The vertical burning test (UL-94) illustrated the plywood samples to have a V-1 rating, with self-extinguishing capabilities. A numerical predictive model has also been developed based on the Fire Dynamics Simulator to predict the time to ignition, time to flameout, and heat release rate trend along with the peak heat release rate—it is shown to have good agreement with the experimental results, with an average correlation coefficient of 0.87.

Ignition and combustion characteristics of micro/nano-Al and Al@Ni alloy powders at elevated pressures

Nanosizing and alloying of aluminum (Al) promisingly improve ignition and combustion performance of Al-based propellants. To aim this, lased-induced ignition and combustion characteristics of micro/nano-Al and aluminum@nickel (Al@Ni) alloy powders at elevated pressures (0.1–3.0 MPa) were investigated and the pressure effect on these characteristics was correspondingly evaluated. Comparative results demonstrate that nanosizing and alloying significantly shorten ignition delay and total burn time at elevated pressures, with ignition delay reduction of 98.04% and 52.28% at 1.0 MPa for nano-Al and Al@Ni alloy compared to micro-Al counterpart. Nanosizing and alloying can decrease crucial pressure values (‘mid-pressure extinction domains’) influencing ignition delay, and promote the transfer from the surface to gaseous combustion mode. Maximum combustion temperatures of nano-Al are higher than micro-Al and Al@Ni alloy. During combustion, the combustion of Al@Ni alloy is further intensified due to the microexplosion, while possibly inhibited at higher pressures.

Characterization and property evaluation of low-cost electrically conductive bamboo charcoal from Dendrocalamus sericeus Munro.

Bamboo (Dendrocalamus sericeus Munro) is fast-growth plant with abundant biomass for conversion to fuel and various uses, including insulation and electronic applications. Bamboo charcoal produced in a low-cost furnace was separated into bamboo coal with electrical conductivity (bamboo coal 1) and without electrical con-ductivity (bamboo coal 2), subjected to proximate analysis and evaluation of adsorption and fuel properties. In addition, structural properties were studied based on surface area analysis using the Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) methods, Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Of the two bamboo coal types, bamboo coal 1 with electrical conductivity had better adsorptive properties, such as a greater iodine number value (240 mg g-1), while the BET and the BJH methods showed that the surface area was 36.653 m² g-1 with a pore volume of 0.052 cm3 g-1 and a pore size of 15.292 Å. In addition, it was better for use as a deodorant and as a solid fuel for cooking with a longer total burning time (81 min). Bamboo coal 2 had lower moisture (5.75%), and ash (6.56%) contents, with a higher heating value (6913 kcal kg-1), indicating that bamboo coal 2 was good for deodorant usage and could have potential for development as an insulator with a hydrophobic and fire-retardant coating material. Bamboo coal 1 had a graphite crystalline structure and could have potential with additional further graphene development for electronic uses.

Shoot flammability differences between forest and savanna trees are driven by leaf dry matter content

Climate change has led to increased fire risk in many tropical regions, with concerning implications for fire-sensitive forests. Understanding the comparative fire ecology of co-occurring fire-prone and fire sensitive habitats and the drivers of canopy fires is paramount for recognizing fire risk and for selecting plants that may be planted in green firebreaks that could mitigate wildfire damage to these habitats. However, baseline plant flammability data is needed from both habitats. To accomplish this, we compared three flammability measures (maximum temperature, total burn time and burnt biomass) by burning branches of 35 species in a fire-protected forest and fire-prone savanna in tropical northeast Australia. We also measured a set of leaf functional traits (leaf area, leaf mass per unit area and leaf dry matter content) on these species and examined their relationship with shoot flammability. We found that maximum temperature, burnt biomass, and burn time were significantly higher in savanna compared to forest species. Leaf area and leaf mass per unit area did not influence flammability measures, but species with higher leaf dry matter content had a higher percentage of biomass burnt, burnt for longer and hotter. Underpinning these observations, savanna species had significantly higher leaf dry matter content than forest species. Our results enable us to recommend species with low flammability that could be used in the green firebreaks in the study area to mitigate fire risk in sensitive forest habitats. Future studies should look experimentally at the effectiveness of green firebreaks using low flammability species, and examine their post fire recovery.

A simple and economical fire test setup for examining the fire retardancy/extinguishing ability of water additive fire‐retardant materials on class A fires

AbstractA portable lab scale test setup (1 × 1 × 0.72 m3) with apparatus and procedure has been illustrated to test the fire extinguishability of fire retardant materials (FRMs) as water additives on class A fires. The main objective was to use selected commercial, eco‐friendly FRM powders such as hydroxides, carbonates, and clays as water additive‐based fire extinguishing agents for suppressing solid fires. FRM powders, namely, Mg(OH)2, Ca(OH)2, CaCO3, and MMT‐Clay were added to water and were mist sprayed on a wooden fire (class A) to test their fire‐suppressing ability. A comparison involving tests with only water (without any additives) was also recorded. The solutions made with FRM additives in water showed promising results in suppressing the fire in comparison to systems with only water as an extinguishing agent. Heat sink materials, such as hydroxides and clays depicted commendable performances in retarding the burning process and almost doubled the capability of fire suppression with low loading. Their heat‐absorbing nature resisted the increase in temperature and slowed down the burning process causing an increase in the total burning time of the crib and avoiding reignition. Whereas, carbonates (CaCO3) showed a faster flame out by the release of CO2 gas, which diluted the oxygen content in the surroundings. The article concludes with a discussion of the requirements for the ideal water mist additive‐based fire extinguishing agent and a recommendation that future work include validation of the laboratory‐scale method based on a comparison with full‐scale suppression data for the same additives.

Evaluating the combustion and flame extension characteristics of cable fire in utility tunnels with spontaneous combustion scenarios: An experimental study

A cable fire in a utility tunnel can cause severe damage to the electric power supply in cities. This study aims to understand the combustion and flame spread characteristics of cable fires, which are mainly caused by overheating from the excessive current at the interconnections of the cables under spontaneous combustion. Fire experiments were conducted in a 1:6 scale model of a utility tunnel to analyse the flame spread characteristics under different heat release rates (HRRs), vertical distances, and transverse distances. The findings of this study show that the total burning time of the cable fire increases as the cable diameter increases, and the HRR also shows an increasing trend. Additionally, the spatial location of the cable fire has a significant impact on the flame spread. The terms Hc* and Dc* are defined to characterize the flame height and a general prediction model of the dimensionless flame height influenced by cable spontaneous combustion is proposed. A dimensionless model is also established to describe the flame spread rate. This research provides valuable guidance to aid in the development of fire safety measures in utility tunnels.

Combustion characteristics of biocoke with added Al powder in oxygen-enriched atmosphere

In this paper, we propose the application of biocoke, which is a high-density solid biofuel, as a solid fuel for hybrid rockets. In this study, we aim to investigate the effect of added aluminum powder on the combustion behavior of biocoke to improve the combustion rate. The average flaming combustion rate, total combustion time, and Al powder reaction ratio are calculated from the mass change during combustion. The results show that the increase in Al powder content accelerates the rate of flaming combustion. The flaming combustion rate is determined by the Al content and oxygen concentration. The combustion rate improvement effect of Al powder blending is approximately 1.15 times higher at 30 mass% Al content. The combustion time does not decrease because the Al powder particles inhibit oxygen diffusion at 30 mass% Al content. The results of this study indicate that another method is needed to increase the combustion rate while maintaining high density.

703 Extubation Success in Pediatric Burn Patients: A 10-Year Review

Abstract Introduction Pediatric burn care presents two unique population subsets that require distinctive care from adult and non-burn patients, respectively. While prior research has led to the creation of best practices for burned adults and non-burn pediatric patients, the standard of care regarding long-term pediatric burn intubation varies widely and deviates from accepted standards in the non-burn pediatric world. In this retrospective review, we analyze one burn center’s experience managing ventilation and extubation of pediatric patients. Methods We reviewed all pediatric patients admitted to the burn and wound care ICU who were intubated for more than 24 hours. Patient data was collected from 2012 through 2022. 442 patients were initially identified and 142 remained after removing screen failures. We analyzed 3 groups which included total burn surface area (TBSA), inhalation injury, and time on the ventilator. Results The first group broken down by TBSA yielded the most significant results in our 7 of 10 metrics. All significant metrics including mortality, length of stay (LOS), and pulmonary hypertension (HTN) were directly correlated to burn TBSA. Patients with higher TBSA were also significantly more likely to require reintubation after coming off the ventilator. Inhalation injury presented on admission was also a significant indicator for developing acute respiratory distress syndrome (ARDS). Patients who remained on the ventilator for >7 days were significantly more likely to develop pulmonary HTN, however mortality and reintubation rates notably did not increase in this group. Conclusions There is much debate in the burn world as to whether standard practices should carry over from other specialties when treating severely burned patients. Much of our data confirms, in pediatric patients, findings of adult patients found in the literature. Mortality, LOS, and time on the ventilator expectedly increased with burn TBSA. Inhalation injury was a significant indicator for ARDS which implies that proper screening for this type of injury is a key to predicting long-term treatment. What is perhaps most notable in this data is the fact that, unlike in the adult burn population, there was no significant difference in mortality between short and long-term intubations. Additionally, patients who required reintubation (n=7) were significantly more likely to have a TBSA >40%, but those who remained on the ventilator >7 days were not more likely to require intubation after extubation. This implies that patients should be left on the ventilator, if necessary, without resorting to aggressive challenge breathing trials for early extubation as is common in adult population. With this data we will also identify our rare cases of pediatric tracheostomy placement and indications for its use. Applicability of Research to Practice This projects shows how intubation of pediatric burn patients can be maintained safely and effectively in the critical care setting.

Fire behaviour of EPDM/NBR panels with paraffin for thermal energy storage applications. Part 1: Fire behaviour

In this work the fire behaviour of elastomeric panels made of an Ethylene-Propylene Diene Monomer (EPDM) rubber filled with a shape-stabilized paraffin with a melting point of 28 °C and covered with a nitrile-butadiene rubber (NBR) envelope, developed for thermal energy storage applications, was investigated for the first time. The panels were prepared using four different flame retardants (FR) and in order to test their efficacy they were dispersed selectively only in the core material, or in the envelope or in both of them. Cone calorimeter and epiradiateur tests pointed out the efficacy of the clay used for the shape stabilization of paraffin and of the external NBR envelope. Moreover, it was possible to demonstrate that a flame retardant based on ammonium polyphosphate and aluminium diethyl phosphinate could achieve the best fire performances. It was also verified that the combination of the FR both in the core and in the envelope led to the best results thanks to the physico-chemical and chemical interactions between clay, talc, kaolin and silicon with ammonium polyphosphate. The best composition allowed to decrease the peak of the heat release rate (HRR) from 318 kW/m2 to 209 kW/m2 and the MARHE (parameter describing the intensity of the combustion over the whole process of thermal degradation) from 239 kW/m2 to 175 kW/m2. Moreover, regarding the ability to self-extinguish, the number of ignitions at epiradiateur test was increased from 4 to 8 within 5 min and the total combustion time from 391 to 288 s. The improvement of the fire behaviour of EPDM/NBR panels with paraffin makes possible future applications in the field of thermal energy storage of buildings.

Effects of hydrogen–oxygen torch igniter combustion to an ABS-GOx hybrid rocket system

A hydrogen-oxygen torch igniter was developed and utilized to study its effects on a solid acrylonitrile butadiene styrene thermoplastic (ABS)-gaseous oxygen (GOx) hybrid rocket motor. The effects thereof are not presently found in literature. An increase of the hydrogen mass flow rate, at constant GOx mass flow rate, led to an increase in the average linear regression rate and a decrease in characteristic ignition time for fuel-lean and stoichiometric hydrogen-oxygen flames. Additionally, extending the duration of hydrogen flow from 10% to 50% of the total burn time led to an increase in the regression rate. Results suggest that the hydrogen-oxygen torch igniter can be used as a reliable starter with reignition capabilities and also for regression rate and ignition delay enhancement that targets the rate-limiting step, pyrolysis, for hybrid rocket combustion at stoichiometric and fuel-lean operating conditions of the torch igniter.

Impact of ash layer retention on heat transfer in piles of vegetation and structure firebrands

The study of firebrands has been of great interest due to the growing threat of fires along the wildland-urban interface (WUI). In previous studies, piles of smoldering firebrands from dowels were found to produce higher heat fluxes than those from branches of the same wood species and geometry. In this study, the difference in burning behavior and heat transfer between these two types of smoldering firebrands are explored through experiments and models, using dowels to broadly represent structure fuels and branches for vegetation fuels. A distinct ash layer was observed in the vegetation firebrands that was not present in the structure firebrands. The deposited ash reduces the mass transport of oxygen within the pile which reduces the heat flux to the surface. In piles of ten, structure firebrands produced higher heat fluxes than vegetation firebrands. A 2D RANS model and an analytical burning model were used to demonstrate the impacts of the ash layer on the total burn time, the heat flux, and the surface temperature of a single firebrand by replicating results from the experiments.

Growth form and functional traits influence the shoot flammability of tropical rainforest species

Canopy fires are increasing globally with anthropogenic climate and land-use changes, even in fire-sensitive rainforest ecosystems. Identifying the ecological drivers that may be aiding canopy fires, such as species or growth form flammability, is crucial to recognising and mitigating fire risks. To address this, we quantified the shoot-flammability of 124 rainforest plant species using an experimental approach. We compared three flammability measures (burnt biomass, total burn time and maximum temperature reached) with plant functional traits across seven different growth forms (i.e., canopy, pioneer, and understory trees; pioneer, understory and invasive shrubs, and vines) and nine common plant families and other higher-level clades, such as conifers, hereafter abbreviated to families. From burning > 600 sun-exposed shoots, we found trees were higher in flammability than shrubs and vines, and the plant families: Sapindaceae, Proteaceae, Fabaceae, and Lauraceae, had especially high flammability, whereas Moraceae was very low. Of the functional traits examined, leaf dry matter content was consistently and significantly positively associated with species flammability. Invasive shrubs as a group were not particularly flammable, although there were exceptions, e.g., wild tobacco (Solanum mauritianum) was highly flammable. This study has two important implications for the management of fire in rainforests. First, we have demonstrated that many tropical rainforest trees may readily burn under severe fire conditions if fire were to reach the rainforest canopy. Second, a large proportion of the > 1 million rainforest trees planted in the Wet Tropics under restoration planting schemes are from our most flammable rainforest plant families, as these families are often recommended for their carbon sequestration potential. Hence, these plantings may be highly vulnerable to fire and if planted along the borders of primary forest they may carry fire into their canopies. Therefore, where fire risk is high, we recommend planting species with low flammability along borders of plantings and forests to act as ‘green firebreaks’ to reduce the risk of fire incursions.

Ignition and combustion behavior of single micron-sized iron particle in hot gas flow

This work investigated the ignition and combustion process of single micron-sized iron particles in the hot gas flow of burned methane-oxygen-nitrogen mixture. The particle emission intensity was recorded by a high-speed camera in different flame conditions. Particle temperature was derived through two-color pyrometry method employing an ICCD camera equipped with a stereoscope. Based on scanning electron microscopy (SEM) image, the microstructure change of iron particles was investigated. Results showed that the temperature of burning particle rose rapidly and was much higher than the ambient temperature. The fresh iron particles mainly went through several stages in hot gas flow: heating, melting, rapid combustion and cooling. Some of them became bright again after cooling. According to the above combustion process, combustion parameters including ignition delay time, accelerated burning time, total burning time and second stage of combustion time were defined. All the above defined parameters were almost linearly increasing with the increase of particle size under the same oxygen concentration. For iron particles with roughly the same size, the ignition delay time, accelerated burning time and total burning time decreased as the effective oxygen concentration increased especially for particle size larger than 40 µm. The second stage of combustion time for particles with similar size were almost the same under different oxygen concentrations. After combustion, most of the particles change from irregular shape to spherical or ellipsoidal shape, and some of them showed hollow shell structure. A phenomenon of nano-sized particles releasing during the iron particles combustion had been identified. The frequently observed luminous tail was attributed to coming from the thermal radiation of the formed nanoparticles, which was supported by the SEM sampling analysis of the combustion products.

An experimental study on thermal runaway and fire behavior of large-format LiNi0.8Co0.1Mn0.1O2 pouch power cell

Lithium-ion batteries are widely promoted in contemporary energy storage and electric vehicles, but battery fires frequently occur, so their thermal runaway and fire behaviors need to be deeply understood. This study investigates the thermal runaway and fire behaviors of 78 Ah LiNi0.8Co0.1Mn0.1O2 pouch batteries under 10 - 50 kW∙m-2 incident heat fluxes, including the combustion behaviors, heat release, and flame temperature. Heat release rate (HRR) based on the oxygen consumption principle (OCP) is modified by measuring the oxygen production of the fully charged cathode during continuous heating. Results show that the heat contributed by the oxygen released from the cathode is negligible (accounting for about 5% of the total heat release (THR)). The 100% and 0% SOC cells follow two different kinds of combustion behaviors. The incident heat flux has little influence on the total burning time, HRR, and THR of 100% SOC cells. It is found that there is a correlation between the time to ignition and the incident heat flux, namely tig∼(Tig−T0q˙′′)0.71. Besides, a flame centerline temperature distribution description model based on a line fire source is established, which is helpful to understand the battery flame structure, and provides a reference for thermal protection and evaluation of the thermal hazard of power supply applications.

Development of Flame Retardant Property on Sodium Silicate Treated Paper Based Materials

The preparation of cellulose-based flame retardant paper treated with sodium silicate and silicon dioxide (SiO2) colloidal particle by simple immersion process is reported. Cellulose-based paper was preheated at 90°C for surface preparation. The heat treated paper was immersed in solution of sodium silicate-SiO2 at different immersion time ranging from 15 min to 24 hrs. Treated solution diffused into paper coated on the paper fiber and filled the void in the paper microstructure. Treated paper was heated at 90°C to convert an impregnated sodium silicate-SiO2 precursor into silicate framework. The treated paper showed Vsym Si-O-Si from siloxane bond at 792 cm-1 which confirmed a presence of SiO2 in paper. Treated paper at 1 hr immersion showed the highest weight percent gain (WPG) of 40% and total combustion time was improved to 14 sec.

Intraspecific variation in shoot flammability in Dracophyllum rosmarinifolium is not predicted by habitat environmental conditions

Flammability is a compound plant trait that can vary significantly across natural populations within species. Investigating intraspecific variation in flammability provides insights into the evolution of plant flammability and inform understanding of wildfire risk and behaviour in different habitats. We measured four flammability variables, representing ignitibility (time to ignition), sustainability (total burning time), combustibility (maximum temperature during burning) and consumability (percentage of biomass consumed by fire) to assess the shoot-level flammability of Dracophyllum rosmarinifolium (G. Forst.) (Ericaceae), a polymorphic endemic species distributed throughout New Zealand. We examined the relationship between flammability components and a suite of climatic and geographic variables (elevation, latitude, mean annual temperature (MAT), mean annual rainfall (MAR) of the sample locations, etc.). We measured shoot-level flammability components of 62 individuals across eight populations. Burning time, maximum temperature and burnt biomass were positively correlated with each other, while ignition score was independent of other flammability components. All flammability components varied significantly across the eight populations. The habitat conditions we considered were not related to any of the shoot-level flammability components of D. rosmarinifolium. Intraspecific variation in flammability in D. rosmarinifolium may be a byproduct of selection on other functional traits, such as leaf size, shoot lipid content, indicating that plant flammability is an incidental result, rather than selected for, at least in ecosystems without fire as a selective force.

Effect of Polymeric Additives on Ignition, Combustion and Flame Characteristics and Soot Deposits of Crude Oil Droplets

ABSTRACT Many oil fires have resulted from the crude oil train derailments in recent years. Given the importance of crude oil shipping by rail to the energy security of the US, it is important to consider various methods that will decrease the likelihood of crude oil catching fire in case of a crude oil derailment. Present study examines the effect of polybutadiene polymer on the combustion properties and soot deposits of Bakken crude. Treating crude oil as multicomponent liquid fuels and polybutadiene as an additive, droplet combustion experiments were conducted with sub-millimeter sized spherical droplets suspended on very fine support fibers. Polybutadiene polymer additive of two different chain lengths has been investigated. Results show that both polymer chain length and origin of crude oil have a significant effect on various combustion properties like combustion rate, ignition delay, and total combustion time. Polymeric additives also change the soot deposit structure and particle size compared to the base fuel. Present research is envisioned to aid in understanding combustion behavior of crude oil as isolated droplets, as well as to generate interest in investigating more polymeric additives for liquid fuels.

Investigation of some factors from the technological processing of leather for upholstery of car seats on their flammability

Natural leather is widely used for car upholstery and has a non-flammability requirement. In the present work, bovine leather intended for upholstery for car seats are studied. Various technological schemes of tanning have been applied, including combined; various finishing methods have been applied and two flame retardants have been used, namely Firex LFS and Flacavon B-45. It was found that the studied methods of combined tanning of investigated leathers do not affect the colour fastness to dry and wet rubbing, but the highest total flame combustion time of the source is given by aluminium-chromium re-tanned leathers and this indicator decreases depending on the type of re-tanning of the tested samples in the following order: chrome, aluminium, vegetable. Flacavon B-45 showed higher efficiency in terms of flame retardancy of the investigated leathers.

The effects of pipe length on gas cloud explosion characteristics in the contraction pipe

ABSTRACT To study the influence of pipe length on premixed gas explosion characteristics in a contraction pipe. A Large Eddy Simulation (LES) and Zimont combustion model was used to simulate the propane/air explosion process at different pipe lengths. The results show that the flame propagation velocity in the contraction pipe increases first and then decreases and reaches its peak at the change of pipe diameter. Compared with the diameter pipe, the flame propagation velocity in the first half of the contraction pipe is reduced by adding the contraction structure. Although the flame propagation velocity increases suddenly after the flame passes through the contraction pipe, the flame propagation process is effectively delayed. Compared with the diameter pipe, the total combustion time of the contraction pipe increases by 44.4%, 30%, and 30%, respectively. Under different pipe lengths, the trend of pressure change is to increase first and then decrease, and the longer the pipe, the greater the maximum explosion pressure in the pipe. The existence of the variable diameter structure leads to a significant increase of the peak pressure in the pipe, and the peak pressure in the contraction pipe is, respectively, 8, 4, and 7 times that in the diameter pipe of the same length. Therefore, in actual industrial production, it is necessary to take safety measures such as pressure relief at the change of pipe diameter to avoid accidents.

Combustion of Laser-Induced Individual Magnesium Microparticles under Natural Convection

Metal magnesium (Mg) fuels have been widely used in rocket propellants. The combustion study on individual Mg microparticles is crucial to the in-depth unveiling of the combustion mechanism of Mg-based propellants. In this paper, a new experimental setup was proposed to directly observe the combustion of individual micron-sized Mg particles, based on laser ignition and microscopic high-speed cinematography. The combustion process of individual Mg microparticles could be directly and clearly observed by the apparatus at high temporal and spatial resolutions. Individual Mg microparticles took gas phase combustion, and mainly underwent four stages: expansion, melting, gasification, ignition, and combustion. The ignition delay time and total combustion time had an exponential decay on the particle diameter, and they had a linear decay on the ignition power density. The melting took a dominant role in the whole burnout time. The gas-phase combustion flame seemed thick, inhomogeneous, and ring-like structure. The combustion model of individual Mg microparticles was built through combining the experimental results with the SEM, XRD, XPS, and EDS analysis of original samples and combustion residues. This study will be beneficial to understand the combustion process and reveal the combustion mechanism of metal microparticles besides Mg.