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Characterizing forest fuel properties in terms of their distribution and flammability behaviour offers useful information for effective fire management. Satellite images provide synoptic images capturing the vegetation state and their change including burn area loss, enabling stratification, and narrowing down the search for further investigation on ground or laboratory. The study investigated the flammability of various forest fuels including sal, teak, bamboo and grass species, by analysing different fuel variables such as moisture content (MC), volatile matter (VM), ash content (AC), fixed carbon (FC), higher heating value (HHV) and minimum ignition temperature (MIT), and exploring the intrinsic relationships between and among them. The teak wood showed low MC (5.08%), high VM (81.91%), low AC (1.1%), high HHV (19.93 MJ/kg), high CF (93.82) indicating high sustainability, combustibility and consumability characteristics. Teak indicated higher flammability characteristics compared to sal, while grass indicated higher sustainability and combustibility characteristics compared to bamboo. Overall woody species (sal and teak) indicated high ignitability and sustainability characteristics over grass and bamboo. Among the plant components, leaves indicated high ignitability, wood indicated high sustainability, combustibility and consumability, and barks indicated low flammability characteristics. This study registers a maiden and early attempt using satellite and laboratory-based analysis to characterize the flammability properties of dominant species of tropical dry forests in eastern India. [ABSTRACT FROM AUTHOR]

Fire safety of food grains in storage, transport and processing facilities requires knowledge of their ignition properties some of which have been determined in this study. Cowpea, lentils, millet, soybean, unshelled peanut, flax (linseed), sunflower, shelled peanut and sesame, at 10% moisture content were studied. A cone calorimeter heater was used to impose radiative heat fluxes of 25, 35 and 47.5 kW/m2 on the food grains to determine the time to piloted ignition concurrently with the surface temperature at ignition (Ts,ig). Ignition temperatures (Tig) were calculated from experimentally determined critical heat fluxes. The thermal response parameter and thermal inertia (k ρ c) essential for the characterization of the ignition of the food grains were also calculated. Thermal response parameter appears to be best suited for distinguishing the ignitability of the food grains. Ignition temperatures range between 239°C and 305°C, while thermal response parameter varies between 261 and 565 kWs0.5/m2. Small particle-sized grains showed higher ignitability. [ABSTRACT FROM AUTHOR]

Motivation: The propensity of plant tissues to burn (i.e. their flammability) is a key trait to understand fire regimes in many ecosystems across the globe. Measuring plant flammability under laboratory conditions allows us to improve both our understanding of plant evolutionary processes and modelling tools for simulating fire hazard and behaviour. Plant flammability has been studied from different but complementary disciplines (e.g. physics, chemistry, ecology, evolution, forestry). However, information is scattered and standardized terminology is lacking, which slows down the progress of research on plant flammability. Here we provide an open access global database on plant flammability traits measured under laboratory conditions aiming to: (a) identify the diversity of methodologies to measure plant flammability under laboratory conditions; (b) standardize the associated terminology; and (c) find geographical, ecological, and taxonomic gaps in our knowledge on plant flammability. We hope this database will stimulate transdisciplinary research and provide useful information to better cope with an increasingly flammable planet. Main Types of Variables Contained: The FLAMITS database contains 19,972 records of 40 flammability variables (classified according to the measured component of flammability). For each record, relevant details of the flammability experiment are given, such as the burning device, the ignition source, and the burnt plant part. In addition, FLAMITS compiles taxonomic and functional data of the studied species and information on the study site (i.e. locality, geographic coordinates, biome, biogeographic realm, and fire activity). Spatial Location and Grain: We compiled data from 295 studies in 39 countries and distributed across 12 biomes worldwide. Time Period and Grain: The last 62.5 years (1961 to 15th May 2023). Major Taxa and Level of Measurement: 1790 plant taxa from 186 families, 883 genera, and 1784 species. Software Format: Five text files (.csv), relationally linked. [ABSTRACT FROM AUTHOR]

Water-blown biopolyurethane (bioPUR) foams are flammable and emit toxic gases during combustion. Herein, a novel approach suggested by the current study is to use different amounts of lignin waste (LigW), which increases the thermal stability and delays the flame spread and sodium silicate (LG), which has foaming ability at high temperatures and acts as a protective layer during a fire. However, there have been no studies carried out to investigate the synergy between these two materials. Therefore, two different ratios, namely 1/1 and 1/2 of LigW/LG, were used to prepare bioPUR foam composites. The obtained bioPUR foam composites with a 1/2 ratio of LigW/LG exhibited inhibition of flame propagation during the ignitability test by 7 s, increased thermal stability at higher temperatures by 40 °C, reduced total smoke production by 17%, reduced carbon monoxide release by 22%, and increased compressive strength by a maximum of 123% and 36% and tensile strength by a maximum of 49% and 30% at 100 °C and 200 °C, respectively, compared to bioPUR foam composites with unmodified LigW. Additionally, thanks to the sufficient compatibility between the polymeric matrix and LigW/LG particles, bioPUR foam composites were characterised by unchanged or even improved physical and mechanical properties, as well as increased glass transition temperature by 16% compared to bioPUR foam composites with unmodified LigW particles, making them suitable for application as a thermal insulating layer in building envelopes. [ABSTRACT FROM AUTHOR]

High-impact mega-fires in many temperate forests and shrublands of the world have called for pre-emptive approaches to mitigate fire risk. Comparative appraisals of the characteristics and flammability of plant fuels can inform fire risk predictions and vegetation management efforts in the wildland–urban interface of such fire-prone regions. Prompted by recent extreme fires in the Cape Floristic Region of South Africa, we assessed the flammability and fuel traits of excised terminal branches of 30 woody species (many of which have never been studied before) that commonly occur as native, alien or invasive species in this region and some other temperate regions of the world. We furthermore assessed changes in flammability and fuel moisture in these species after partial drying of excised branches under ambient conditions for 2–4 weeks to simulate extreme drought conditions. Several prominent alien invasive taxa in the study region and elsewhere showed high flammability, namely Pinus radiata (median flammability index score of 2.5), Eucalyptus camaldulensis (2.3), Acacia mearnsii (2.2), Acacia melanoxylon (2.2), Pinus pinaster (2.2), Acacia cyclops (2.0) and Cestrum laevigatum (2.0). The high fire risk posed by these species needs to be considered in potential further plantings and in invasive plant clearing efforts. Conversely, Osteospermum moniliferum (median flammability index score 0.9) and Acacia saligna (1.3) are species with large invasive ranges that showed low flammability, which may suppress fire regimes in fire-prone ecosystems but present suitable options for fire mitigation in their native ranges. Fynbos and thicket species native to the study region mostly displayed high and low flammability, respectively. Species of which the flammability is likely to increase disproportionately under extreme drought conditions include select fynbos and thicket species, and among the alien invasives, all four Acacia species, Leptospermum laevigatum, Callistemon viminalis, Pinus pinaster and Osteospermum moniliferum. Management of these species should be a secondary priority (after high flammability species) in the wildland–urban interface and other high fire risk areas.

Under high temperatures, fiber-reinforced polymers are destroyed, releasing heat, smoke, and harmful volatile substances. Therefore, composite structural elements must have sufficient fire resistance to meet the requirements established by building codes and regulations. Fire resistance of composite materials can be improved by using mineral fillers as flame-retardant additives in resin compositions. This article analyzes the effect of fire-retardant additives on mechanical properties and fire behavior of pultruded composite profiles. Five resin mixtures based on vinyl ester epoxy and on brominated vinyl ester epoxy modified with alumina trihydrate and triphenyl phosphate were prepared for pultrusion of strip profiles of 150 mm × 3.5 mm. A series of tests have been conducted to determine mechanical properties (tensile, flexural, compression, and interlaminar shear) and fire behavior (ignitability, flammability, combustibility, toxicity, smoke generation, and flame spread) of composites. It was found that additives impair mechanical properties of materials, as they the take place of reinforcing fibers and reduce the volume fraction of reinforcing fibers. Profiles based on non-brominated vinyl ester epoxy have higher tensile, compressive, and flexural properties than those based on brominated vinyl ester epoxy by 7%, 30%, and 36%, respectively. Profiles based on non-brominated epoxy resin emit less smoke compared to those based on brominated epoxy resin. Brominated epoxy-based profiles have a flue gas temperature which is seven times lower compared to those based on the non-brominated epoxy. Mineral fillers retard the spread of flame over the composite material surface by as much as 4 times and reduce smoke generation by 30%. [ABSTRACT FROM AUTHOR]

The ignition of hydrogen in compression ignition (CI) engines by adding noble gas as a working gas can yield excellent thermal efficiency due to its high specific heat ratio. This paper emphasizes the potential of helium–oxygen atmosphere for hydrogen combustion in CI engines and provides data on the engine configuration. A simulation was conducted using Converge CFD software based on the Yanmar NF19SK engine parameters. Helium–oxygen atmosphere compression show promising hydrogen autoignition results with the in-cylinder temperature was significantly higher than that of air during the compression stroke. In a compression ignition engine with a low compression ratio (CR) and intake temperature, helium–oxygen atmosphere is recognized as the best working gas for hydrogen combustion. The ambient intake temperature was sufficient for hydrogen ignition in low CR with minimal heat flux effect. The best intake temperature for optimum engine efficiency in a low CR engine is 340 K and the engine compression ratio for optimum engine efficiency at ambient intake temperature is CR12 with an acceptable cylinder wall heat flux value. The helium–oxygen atmosphere as a working gas for hydrogen combustion in CI engines should be consider based on the parameter provided for clean energy transition with higher thermal efficiency.

IntroductionA variety of plant traits, from architectural to the cellular level, have been connected to flammability, but intraspecific variability of plant traits (ITV) and components of flammability is poorly studied. The lack of knowledge about ITV of plant traits related to flammability appears to be a major shortcoming in further interpreting species flammability and fire behavior and incorporating the data into models.MethodsMorpho-ecophysiological traits (width, length, thickness, weight, area, volume, moisture content, flatness, specific leaf area, density of leaf tissue, ratio of area to volume) and time-to-ignition of fresh foliage were measured in seven populations of Picea omorika.ResultsAll leaf traits are presented along with their correlations to the flammability trait. The seven populations differed in terms of fresh leaves’ time-to-ignition. Differences among populations in morpho-ecophysiological traits were also significant but not consistent among populations. PCA classified 49 elements into three different groups, where three populations were clustered by higher leaf area-related traits, other three populations were clustered by higher leaf length, volume, thickness, time-to-ignition, density index, moisture content, width, weight, and one population was classified between the two main groups. The first two principal components accounted for 87% of the total variance: variability in leaf area- and leaf weight-derived parameters (specific leaf area and density index) and time-to-ignition primarily defined the formation of the first axis, while variability in leaf flatness (based on leaf weight and thickness) primarily contributed to the formation of the second axis.DiscussionResults suggest high ITV in natural populations of P. omorika regardless of site fire history.

Water-blown biopolyurethane (bioPUR) foams are flammable and emit toxic gases during combustion. Herein, a novel approach suggested by the current study is to use different amounts of lignin waste (LigW), which increases the thermal stability and delays the flame spread and sodium silicate (LG), which has foaming ability at high temperatures and acts as a protective layer during a fire. However, there have been no studies carried out to investigate the synergy between these two materials. Therefore, two different ratios, namely 1/1 and 1/2 of LigW/LG, were used to prepare bioPUR foam composites. The obtained bioPUR foam composites with a 1/2 ratio of LigW/LG exhibited inhibition of flame propagation during the ignitability test by 7 s, increased thermal stability at higher temperatures by 40 °C, reduced total smoke production by 17%, reduced carbon monoxide release by 22%, and increased compressive strength by a maximum of 123% and 36% and tensile strength by a maximum of 49% and 30% at 100 °C and 200 °C, respectively, compared to bioPUR foam composites with unmodified LigW. Additionally, thanks to the sufficient compatibility between the polymeric matrix and LigW/LG particles, bioPUR foam composites were characterised by unchanged or even improved physical and mechanical properties, as well as increased glass transition temperature by 16% compared to bioPUR foam composites with unmodified LigW particles, making them suitable for application as a thermal insulating layer in building envelopes.

Industrial wastes are considered a major cause of environmental pollution, and studies on valorizing these wastes and converting them into value-added products have gained importance. This study investigated the potential use of buffing dust (BD) waste from chromium-tanned leather as a filler for polyurethane (PU) matrix. PU + BD composites containing different concentrations of filler, ranging from 1 to 4%, were produced. Compressive strength, thermal stability, thermal conductivity, and flammability of PU + BD composites were analyzed. Regarding the compression module, PU with 2% filler performed similarly to neat PU, while 1% and 3% provided comparable results. The addition of 3% leather waste is feasible and preferable as it enables the incorporation of a higher amount of waste without compromising the compressive strength properties of the PU. PU + BD composites had similar heat isolation properties to neat PU and reduced the flammability of the polyurethane composites. Incorporating leather waste particles into PU + BD composites could be a sustainable promising alternative approach for reducing the flammability of PU, where lower flammability is required. [ABSTRACT FROM AUTHOR]

The results of development of a next-generation Mg–REM–Zr fireproof cast magnesium alloy are presented. Commercially available magnesium alloys do not have a high strength at room temperature and a sufficient level of heat resistance. A unique Russian cast magnesium alloy with simultaneously stable high specified properties is developed. In addition, the ignition temperature achieved allows the developed alloy to be attributed to fireproof magnesium alloys. The optimum regime ensuring its high strength properties is chosen based on the research of its heat-treatment parameters. [ABSTRACT FROM AUTHOR]

Polyurethane (PUR) foams are some of the most promising thermal insulating materials because of their high flammability, but further applications are limited. Therefore, the development of flame-retardant materials with sufficient strength characteristics, water resistance, and low thermal insulating properties is of great importance to the modern building industry. This study evaluates the possibility of a vacuum-based liquid glass (LG) infusion into bio-based fillers, in this case, sunflower press cake (SFP) particles, to improve the mechanical performance, water absorption, thermal insulation, ignitability, thermal stability, and flame retardancy of the resulting polyurethane (PUR) foam composites. The main findings show that LG slightly improves the thermal stability and highly contributes to the ignitability and flame retardancy of the resulting products. Most importantly, from 10 wt.% to 30 wt.%, the SFP/LG filler reduces the thermal conductivity and water absorption values by up to 20% and 50%, respectively, and increases the compressive strength by up to 110%. The results obtained indicate that the proposed SFP/LG filler-modified PUR foam composites are suitable for applications as thermal insulation materials in building structures. [ABSTRACT FROM AUTHOR]

Hydrogen eliminates carbon emissions from compression ignition (CI) engines, while noble gases eliminate nitrogen oxide (NOx) emissions by replacing nitrogen. Noble gases can increase the in-cylinder temperature during the compression stroke due to their high specific heat ratio. This paper aims to find the optimum parameters for hydrogen combustion in an argon–oxygen atmosphere and to study hydrogen combustion in all noble gases, providing hydrogen combustion data with suitable engine parameters to predict hydrogen ignitability under different conditions. Simulations are performed with Converge CFD software based on the Yanmar NF19SK direct injection CI (DICI) engine parameters. The results are validated with the experimental results of hydrogen combustion in an argon–oxygen atmosphere with a rapid compression expansion machine (RCEM), and modifications of the hydrogen injection timing and initial temperature are proposed. Hydrogen ignition in an argon atmosphere is dependent on a minimum initial temperature of 340 K, but the combustion is slightly unstable. Helium and neon are found to be suitable for hydrogen combustion in low compression ratio (CR) engines. However, krypton and xenon require temperature modification and a high CR for stable ignition. Detailed parameter recommendations are needed to improve hydrogen ignitability in conventional diesel engines with the least engine modification.

In June 2017, extreme fires along the southern Cape coast of South Africa burnt native fynbos and thicket vegetation and caused extensive damage to plantations and residential properties. Invasive alien plants (IAPs) occur commonly in the area and were thought to have changed the behaviour of these fires through their modification of fuel properties relative to that of native vegetation. This study experimentally compared various measures of flammability across groups of native and alien invasive shrub species in relation to their fuel traits. Live plant shoots of 30 species (10 species each of native fynbos, native thicket, and IAPs) were sampled to measure live fuel moisture, dry biomass, fuel bed porosity and the proportions of fine-, coarseand dead fuels. These shoots were burnt experimentally, and flammability measured in terms of maximum temperature (combustibility), completeness of burn (consumability), and time-to-ignition (ignitability). Multiple regression models were used to assess the relationships between flammability responses and fuel traits, while the Kruskal-Wallis H test was used to establish if differences existed in flammability measures and fuel traits among the vegetation groups. Dry biomass significantly enhanced, while live fuel moisture significantly reduced, maximum temperature, whereas the proportion of fine fuels significantly increased completeness of burn. Unlike other similar studies, the proportion of dead fuels and fuel bed porosity were not retained by any of the models to account for variation in flammability. Species of fynbos and IAPs generally exhibited greater flammability in the form of higher completeness of burn and more rapid ignition than species of thicket. Little distinction in flammability and fuel traits could be made between species of fynbos and IAPs, except that fynbos species had a greater proportion of fine fuels. Thicket species had higher proportions of coarse fuels and greater dry biomass (~fuel loading) than species of fynbos and IAPs. Live fuel moisture did not differ among the vegetation groups, contrary to the literature often ascribing variation in flammability to fuel moisture differences. The fuel traits investigated only explained 21-53% of the variation in flammability and large variation was evident among species within vegetation groups suggesting that species-specific and in situ community-level investigations are warranted, particularly in regard fuel moisture and chemical contents. [ABSTRACT FROM AUTHOR]

In June 2017, extreme fires along the southern Cape coast of South Africa burnt native fynbos and thicket vegetation and caused extensive damage to plantations and residential properties. Invasive alien plants (IAPs) occur commonly in the area and were thought to have changed the behaviour of these fires through their modification of fuel properties relative to that of native vegetation. This study experimentally compared various measures of flammability across groups of native and alien invasive shrub species in relation to their fuel traits. Live plant shoots of 30 species (10 species each of native fynbos, native thicket, and IAPs) were sampled to measure live fuel moisture, dry biomass, fuel bed porosity and the proportions of fine-, coarse- and dead fuels. These shoots were burnt experimentally, and flammability measured in terms of maximum temperature (combustibility), completeness of burn (consumability), and time-to-ignition (ignitability). Multiple regression models were used to assess the relationships between flammability responses and fuel traits, while the Kruskal-Wallis H test was used to establish if differences existed in flammability measures and fuel traits among the vegetation groups. Dry biomass significantly enhanced, while live fuel moisture significantly reduced, maximum temperature, whereas the proportion of fine fuels significantly increased completeness of burn. Unlike other similar studies, the proportion of dead fuels and fuel bed porosity were not retained by any of the models to account for variation in flammability. Species of fynbos and IAPs generally exhibited greater flammability in the form of higher completeness of burn and more rapid ignition than species of thicket. Little distinction in flammability and fuel traits could be made between species of fynbos and IAPs, except that fynbos species had a greater proportion of fine fuels. Thicket species had higher proportions of coarse fuels and greater dry biomass (~fuel loading) than species of fynbos and IAPs. Live fuel moisture did not differ among the vegetation groups, contrary to the literature often ascribing variation in flammability to fuel moisture differences. The fuel traits investigated only explained 21–53% of the variation in flammability and large variation was evident among species within vegetation groups suggesting that species-specific and in situ community-level investigations are warranted, particularly in regard fuel moisture and chemical contents.

This study numerically investigates the effect of dripping on the ignitability of a vertically-oriented thermoplastic material subjected to localized radiant heating within a 2D domain. Thermoplastic material is modeled as a phase-change material with the prescribed solidification/melting temperature, and its rate of gasification (pyrolysis) process is described by the Arrhenius law. Molten matter can move downward due to the gravitational force, and accordingly, the gasification (pyrolyzed) surface area vary over time. Time-dependent heat and mass transport processes, including global one-step pyrolysis reaction are solved using FLUENT combined with appropriate user-definition functions (UDFs) developed by the authors. In order to simplify the problem, gas-phase kinetics were not considered, instead, the (expected) ignitability was estimated on the basis of the fuel mass flux evolved from the interface. The viscosity of the molten matter was varied as a numerical parameter in order to modify the degree of time-dependent deformation of the molten matter, and the influence of its dripping on ignitability is discussed. The numerical results clearly indicate that dripping occurs quickly when lower viscosity is imposed, although the trajectory of its mass-center yields a similar trend, irrespective of the viscosity (its moving speed greatly differs, though). As the dripping was pronounced, the thickness of the molten matter in the heated zone became thinner causing it to heat up quickly, at such point immediate gasification occurred, resulting in the ignition delay time becoming shorter. Interestingly, as the dripping was further promoted in a very-low viscosity case, the molten matter quickly flows-off prior to substantial gasification is occurring, resulting in the chance of ignition being inhibited. In this respect, dripping exhibited two competing effects on ignitability, implying that there were optimal conditions for the ignition with the shortest delay time. A simple strategy to mimic such a dripping effect in a conventional numerical model (without developing a dripping model) is also discussed. [ABSTRACT FROM AUTHOR]

The thermophysical properties and combustion characteristics of PIB thickened jet fuel are investigated based upon both aims of expanding basic combustion theory (i.e., the coupled gas phase and liquid phase flows and heat transfer involving flame spread over liquid fuel) and potential practical applications (i.e., the oil additive in two-stroke gasoline engine and in-situ burning of leaked oils). The effects of PIB on the thermophysical parameters of jet fuel including density, flashpoint, viscosity and surface tension are experimentally measured. The logarithm of the dynamic viscosity varies linearly with the proportion of PIB, which is in good agreement with predictions. Then, the impact of PIB on fire safety of jet fuel is examined through flame spread and ignition experiments. The temperature evolution, flame spread rate, length and velocity of subsurface flow are quantitated and analyzed. The addition of PIB into jet fuel reduces the flame spread rate, but promotes the ignitability. The viscosity augment plays the principal role in hindering flame spreading over thickened jet fuel. [ABSTRACT FROM AUTHOR]

Biochar is a fairly new material in the research arena with limited information on safety aspects related to transportation, storage, disposal or field application methods. The objective of this research was to assess the flammability characteristics of fast pyrolysis biochars with test methods EPA 1030 and ASTM 4982. Results indicated that biochar is a non-flammable substance when tested with EPA 1030 ignitability of solids. However, when tested with ASTM D4982, a fast screening method, biochars showed potential risks of flammability. However, the addition of 20-50% moisture reduced any flammability concern. Fast pyrolysis biochar was more prone to be flammable than traditional charcoal and slow pyrolysis biochar tested in this study. Still, fast pyrolysis biochars presented lower flammability potential (ASTM 4982) in comparison to its precursor biomass. The flammability propagation measured with EPA 1030, had high correlations with oxygen content and surface area of the fast pyrolysis biochar. The combustion reaction of fast pyrolysis biochar is a flameless combustion process, with a slow burning rate, and most commonly exhibiting a hot ember smoldering propagation front. This paper illustrates the necessity of performing recurring tests due to biochar"™s intrinsic variability stemming from the different modes of production and feedstock used.

Fuel moisture content is one of the key parameters controlling the flaming ignition of wildland fuel. However, the role of fuel moisture content in assessing the flammability of different fuel curing (dead and live fuel) is still not well understood. This paper presents the results of ignition tests of fuel beds consisting of dead and live Eucalyptus saligna leaves under a wide range of moisture contents. External heat flux and fuel moisture content are shown to significantly influence time to ignition and mass loss rate at the ignition of Eucalyptus saligna leaves, thus illustrating distinctive heating processes in the fuel bed. The thermal behaviour of the leaf bed before ignition is analysed using the analytical solution to the heat conduction equation, as the classical ignition correlations yield inconclusive results. This approach allows identification of thermally thick and thin behaviours for distinct ranges of heating, with the transition (thermally intermediate) region observed at higher external heat fluxes for higher moisture content. Additionally, a flammability assessment based on time to ignition confirms the inadequacy of the common assumption that live fuel can be considered as moist dead fuel. The flammability and thermal behaviour of dead and live Eucalyptus saligna leaves before ignition are studied. The results indicate that the flammability of dead and live leaves cannot be solely assessed by moisture content. The external heat flux and fuel moisture content govern thermal behaviour before ignition. [ABSTRACT FROM AUTHOR]

Polyurethane (PUR) foams are some of the most promising thermal insulating materials because of their high flammability, but further applications are limited. Therefore, the development of flame-retardant materials with sufficient strength characteristics, water resistance, and low thermal insulating properties is of great importance to the modern building industry. This study evaluates the possibility of a vacuum-based liquid glass (LG) infusion into bio-based fillers, in this case, sunflower press cake (SFP) particles, to improve the mechanical performance, water absorption, thermal insulation, ignitability, thermal stability, and flame retardancy of the resulting polyurethane (PUR) foam composites. The main findings show that LG slightly improves the thermal stability and highly contributes to the ignitability and flame retardancy of the resulting products. Most importantly, from 10 wt.% to 30 wt.%, the SFP/LG filler reduces the thermal conductivity and water absorption values by up to 20% and 50%, respectively, and increases the compressive strength by up to 110%. The results obtained indicate that the proposed SFP/LG filler-modified PUR foam composites are suitable for applications as thermal insulation materials in building structures.

Summary: Vegetation–fire feedbacks are important for determining the distribution of forest and savanna. To understand how vegetation structure controls these feedbacks, we quantified flammability across gradients of tree density from grassland to forest in the Brazilian Cerrado.We experimentally burned 102 plots, for which we measured vegetation structure, fuels, microclimate, ignition success and fire behavior.Tree density had strong negative effects on ignition success, rate of spread, fire‐line intensity and flame height. Declining grass biomass was the principal cause of this decline in flammability as tree density increased, but increasing fuel moisture contributed. Although the response of flammability to tree cover often is portrayed as an abrupt, largely invariant threshold, we found the response to be gradual, with considerable variability driven largely by temporal changes in atmospheric humidity. Even when accounting for humidity, flammability at intermediate tree densities cannot be predicted reliably.Fire spread in savanna–forest mosaics is not as deterministic as often assumed, but may appear so where vegetation boundaries are already sharp. Where transitions are diffuse, fire spread is difficult to predict, but should become increasingly predictable over multiple fire cycles, as boundaries are progressively sharpened until flammability appears to respond in a threshold‐like manner. [ABSTRACT FROM AUTHOR]

Smoldering fire exhibits low-velocity combustion rates and is a threat commonly presented in agriculture grain storages. Some physical and chemical properties of the grain, including particle size, porosity, moisture, and the environmental conditions influence the propagation of the smoldering process. Many works evaluate the conditions to develop smoldering combustion based on particulate size and granular materials. However, only a few studies focusing on smoldering propagation in cornflour and granular grains. In this work, different particle diameters (181.6 ​μm, 776.4 ​μm and 1411 ​μm) and moisture contents (0% and 15%) of corn are examined to understand the corresponding impact on the smoldering propagation. To achieve this, samples of corn were placed inside a cylindrical reactor with thermocouples distributed along the apparatus’ central axis and heated by a hot plate, then the smoldering reaction with a rising heating transfer profile was analyzed. Our results demonstrate how changing storage conditions can profoundly influence the smoldering propagation within a pile of corn.

In order to study the influence of natural wood thickness on the flammability and fire performance, an experimental studies of fire parameters under external constant heat flux by piloted ignition of wood timber with different thicknesses (8, 10, 13, 15 mm) were conducted using cone calorimeter approach, by testing procedure prescribed in accordance with international organization for standardization. These parameters include: ignitibility, heat release rate, effective heat of combustion, total heat release, mass loss rate, smoke specific extinction area, and the yield of carbon monoxide. Four species of wood timber, namely pine, maple, oak, and walnut, were exposed horizontally under external heat flux 50 kW/m². Thermal degradation effects of various species were observed. The obtainable data will be reported to develop a distinct national building code in Jordan and to select the suitable materials for designing of fire safety in buildings of different uses. A good compatible agreement between calculated and experimented results has been obtained. The results indicated that total heat release rate increase with increase thickness of specimen. It is observed that, the time to ignition is very small (around 12 seconds) for all species whatever the thickness is. Heat release rate for the different types of specimens with different thicknesses have been presented. Results show as the thickness of oak specimen increased: 8 mm, 10 mm, 13 mm and 15 mm, the corresponding mass loss depletions are 43%, 34%, 25%, and 21%, respectively. [ABSTRACT FROM AUTHOR]

Abstract This work studied the piloted ignition of electrical wires in both normal gravity and microgravity using the laser-induced spark. Unique experiments were conducted in the microgravity parabolic flight with laboratory wires under the oxygen concentration of 14–21% and external radiation of up to 15.9 kW/m2. The wire sample consists of a 2.5-mm thick core, using the solid copper (Cu) or the hollow stainless steel (SS) tube, and a 0.75-mm thick black polyethylene (PE) insulation. This is the first piloted-ignition experiment on solid fuel in microgravity with the laser-induced spark as the pilot. Experimental results show that regardless of the oxygen level, the ignition delay time is always smaller in microgravity than in normal gravity, indicating a higher fire risk in the microgravity space environment. As the heat flux and the oxygen concentration increase, auto-ignition is observed. Moreover, if the core is exposed to the external heating source, it can heat the insulation to promote the ignition, different from the heat sink found in past ignition research. This unique research provides valuable information about the fire risk of electrical wire in microgravity and future long-term space travel. [ABSTRACT FROM AUTHOR]

Ignitability is one of the parameters that characterize the behaviour of building materials on flame action. The Ignitability Small Attack Flame fire test is used for the classification of building products by their reaction to fire. On the basis of the Ignitability fire test it can be determined that the tested material will be classified into the class E by reaction to fire. The Ignitability Small Attack Flame fire test precede the Single Burning Item fire test, that is used for classification of building products to class D, C, B, A2. The results of the Ignitability fire test were carried out as part of the research on the properties of gypsum composite with natural fiber reinforcement. As part of the research series of ignitability tests on two types of gypsum composite were carried out. The first type was a gypsum composite reinforced with straw fibres. The second type was composite reinforced with wooden fibres. Developed composite materials could be used in the future as board materials and therefore the determination of their fire parameters is a very important part of research. The results of the fire tests have shown that the developed material has a very good flame resistance. [ABSTRACT FROM AUTHOR]

Thermal modification is a widely used wood protection method. This method has attracted attention because there are no toxic chemicals used in the process. The influence of thermal modification was investigated relative to the ignitability and the mass burning rate of Norway spruce wood (Picea abies). The spruce wood samples were subjected to temperatures of 100 °C, 150 °C, 200 °C, 220 °C, 240 °C, and 260 °C for durations of 1 h, 3 h, and 5 h. The treatment at temperatures higher than 200 °C resulted in a lower mass loss at 600 s and a lower average relative burning rate, but it did not influence ignition time, the flame-died-out time, and maximum relative burning rate. The class of reaction to fire of the spruce wood samples was not changed due to the treatment. Therefore, it can be stated that the thermal treatment at temperatures below 200 °C does not influence the fire safety of an important class of wooden products. [ABSTRACT FROM AUTHOR]

Abstract Hydrogen gas concentrations and jet velocities were measured downstream by a high response speed flame ionization detector and PIV (Particle Image Velocimetry) in order to investigate the characteristics of dispersion and ignitability for 40–82 MPa high-pressurized hydrogen jet discharged from a nozzle with 0.2 mm diameter. The light emitted from both OH radical and water vapor species yielded from hydrogen combustion, ignited by an electric spark, were recorded by two high speed cameras. From the results, the empirical formula concerning the relationships for time-averaged concentrations, concentration fluctuations and ignition probability were obtained to suggest that they would be independent of hydrogen discharge pressure. Highlights • Dispersion and ignitability of hydrogen jets pressurized at 82 MPa were investigated. • Hydrogen gas concentration was measured by a high response flame ionization detector. • The light emitted from OH radicals were recorded by a high speed camera. • The relationships for ignition probability and concentration field were obtained. • The relations would be expected to be independent of hydrogen discharge pressure. [ABSTRACT FROM AUTHOR]

This work presents a study of the fire reaction of two types of decking sections (wood and thermoplastic) exposed to a radiant heat source. The flammability was studied at two scales: a cone calorimeter was used at product scale (36 cm2) and at assembly scale (around 1300 cm2), experiments were performed under a Large Scale Heat Release calorimeter with a radiant burner. Since the wood decking sections have gaps, the influence of the orientation of the sections facing the burner was further investigated. At product scale, the wood sections ignite sooner than the thermoplastic sections whereas the thermoplastic sections have a higher peak of heat release rate. At assembly scale, the thermoplastic decking sections ignite sooner and have a higher peak of heat release rate than wood decking sections, regardless of the orientation adopted. Wood sections with boards oriented perpendicular to the burner ignite sooner and have a higher peak of heat release rate than those oriented parallel. The fire tests at both scales highlighted the influence of the shape of the products on their ability to ignite. Flame retardant should be included in decking assemblies to decrease the fire risk at WUI. [ABSTRACT FROM AUTHOR]

Nanocomposite is a promising method to reduce fire hazards of polymers. Specifically due to increased interfacial area between polymer and nanofillers, polymer nanocomposites have an advantage in reducing fire hazards efficiently even when the flame retardant additives are at a concentration of 5 mass% or less. In theory, crosslinking between the polymer chains can create a carbon-dense structure to enhance char formation, which can further promote the flame retardancy. However, little research has been done to explore the flammability of crosslinking polymer nanocomposites with a low concentration of nanosilica particles. In this study, crosslinked and non-crosslinked poly (methyl methacrylate) (PMMA) nanocomposites of a low concentration of nanosilica particles have been prepared via an in situ method. Their fire properties were tested by using the cone calorimeter at the heat flux of 50 kW m. Although silica-containing flame retardants tend to negatively affect the ignitability and soot production especially at a high concentration, through the condensed phase mechanism, the samples of high loading rate of nanosilica particles show better fire retardancy performance in the aspect of flammability, including decreased heat release rate, mass loss rate, and total heat release. Additionally, crosslinking indeed attributes to the less intensive combustion of crosslinked PMMA samples, especially at a low concentration of nanosilica. The combination of nanosilica particles with the modification of the internal structure of the polymer nanocomposites might be a good strategy to improve fire retardancy. [ABSTRACT FROM AUTHOR]

Diffusion methane-air flames in Y-shaped meso-scale combustors of three different diameters (i.e., d = 4, 5 and 6 mm) were experimentally studied. The impact of adding fibrous porous media on mixture ignitability, flame stability and flammable range were systematically investigated. Without porous media, the mixture can only be ignited at positions farther than a certain distance, which was defined as ignition distance in this paper. The ignition distance increases with an increasing inlet velocity and decreases with a decreasing channel diameter. The flame cannot be stabilized and propagates downstream with an inclination angle. The propagation velocity increases with the increase of inlet velocity or with the decrease of channel diameter. With the addition of porous media, the mixture can be ignited near the splitter due to improved methane/air mixing. Moreover, the flames become more stable and stationary flames were observed under lower velocities in the combustors of d = 5 mm and 6 mm with fibrous porous media. Furthermore, the application of porous media can significantly expand the flammable range. In summary, the combustion performances can be notably improved by the application of fibrous porous media. [ABSTRACT FROM AUTHOR]

A novel platform and procedure were developed to characterize the ignitability of Alaska North Slope (ANS) crude oil and its water-in-oil products with water content up to 60% at low temperatures (− 20–0 °C). Time to ignition, critical heat flux, in-depth temperature profiles were investigated. It was observed that a cold boundary and consequent low oil temperature increased the thermal inertia of the oil/mixture and consequently the time to sustained ignition also increased. As the water content in the ANS water-in-oil mixture increased, the critical heat flux for ignition was found to increase. This is mainly because of an increase in the thermal conductivity of the mixture with the addition of saltwater. The results of the study can be used towards design of ignition strategies and technologies for in situ burning of oil spills in cold climates such as the Arctic. [ABSTRACT FROM AUTHOR]

This paper deals with the determination of selected fire properties of spruce wood. It describes the general characteristics of spruce wood, microscopic and macroscopic features. Broad application of this material requires the assessment of its properties regarding the fire aspects, being a cause of fire in forests or due to frequent occurrence of wildland fires in the Slovak territory, and being a flammable material used in building industry, furniture industry, etc. This paper analyses the following fire properties: flash-ignition temperature, spontaneous ignition temperature, mass burning rate, ignitability of material exposed to a small open flame.

A predicted ignitability index for diesel combustion (the predicted diesel ignitability index) has been established with multiple regression analysis of parameters related to the bond structures in hydrocarbons as explanatory variables and the cetane numbers as a response variable. There were 116 hydrocarbons with known cetane numbers and molecular structures used for the calculations. The numbers of carbon atoms for the seven categories—CM (carbon in a main-chain), CSL (carbon in a side-chain longer than five atoms), C1A (carbon in a single-benzene ring), C2A (carbon in a double-benzene ring), CNA (carbon in a naphtheno-benzene ring), C1N (carbon in a single-saturated six-membered ring), and C2N (carbon in a double-saturated six-membered ring)—were included. The predicted diesel ignitability index was expressed with these seven parameters in the following equation PDI index = 3 . 95 C M + 0 . 99 C SL − 3 . 99 C 1 A − 3 . 31 C 2 A − 2 . 56 C NA − 2 . 15 C 1 N − 0 . 96 C 2 N + 25 . 7 The equation of the predicted diesel ignitability index comprises one-dimensional mono-nominal formulas for each molecular structure variable, suggesting the quantitative influence of the variable on the ignitability. There is good correlation between the predicted diesel ignitability index and the cetane number, showing the coefficient of determination with an R2 of 0.82. The simulation was validated with the ignition delays of 31 blends of hydrocarbons and gas to liquid in a diesel engine. The predicted diesel ignitability index showed better correlations with the measured ignition delays than the cetane number at all three intake oxygen concentrations examined here. Especially, at a low intake oxygen concentration, there was significant scattering between the cetane number and the ignition delay for low cetane number fuels, where the predicted diesel ignitability index showed much smaller scattering. [ABSTRACT FROM AUTHOR]

Analysis of postulated sodium fire events in the systems of Sodium cooled Fast Reactors (SFRs) is very important in the safety evaluation. Ejection of primary sodium into the Reactor Containment Building (RCB) and resultant sodium fire thermal consequences under very low probability energetic Core Disruptive Accident (CDA) forms the design basis of RCB, which is the final barrier for radioactivity reaching to the public. Among different possible modes of sodium fires generated by accidental leaks, the spray fire will cause severe thermal consequences due to divided and exposed burning of sodium in droplet form. This paper describes the sodium spray fire analysis code NAFCON-SF developed for the realistic evaluation of thermal consequences in enclosed air containment under postulated sodium leak scenarios. The code simulates two stages of sodium droplet combustion in the air using reaction rate based pre-ignition model and mass transfer based vapour phase combustion model to predict the ignition and combustion of individual sodium droplets. The code uses a distribution system to represent the possible sizes of sodium droplets in spray fire. The burning droplets are tracked from leak location to the floor of chamber by using the model for spherical droplet motion. The burning rate of sodium spray is evaluated as the sum of burning rates of all the droplets constituting the spray. The code employs a transient energy balance on chamber gas to evaluate its time varying temperature and pressure, by considering simultaneous heat addition from spray fire and heat loss to the chamber walls. The NAFCON-SF code has been validated for a wide range of influential parameters with different sodium spray fire test results available in the literature. The code predicted trends are in line with experimental results and the values of peak pressure rise and maximum gas temperature are in fairly good agreement with experimental results for short duration spray fire scenarios. The present code predictions are also compared with NACOM spray fire analysis code predictions and these results show the realistic evaluation of spray fire consequences by NAFCON-SF code compared to the experimental results. The validated code is a valuable tool for the safety analysis of postulated sodium spray fire scenarios in SFR. Further, the code will be validated with in-house large scale sodium spray fire experimental studies. [ABSTRACT FROM AUTHOR]

This paper investigates the combustion characteristics of 12 wood species natural to Brazil. A mass loss cone calorimeter was used to obtain the properties associated with (i) heat release rate (HRR), peak HRR, and total heat released; (ii) total mass loss and mass loss rate; (iii) average effective heat of combustion; and (iv) time to ignition, time of pyrolysis and temperature of ignition. The samples used in this work were as follows: (i) prepared in accordance to ISO 5660-1:2002; (ii) oven dried; (iii) irradiated with a constant heat flux of 50 kW/m2; and (iv) exhibit wood fiber orientation in a plane orthogonal to the flux incidence. Finally, the paper explores the possibility of linking the obtained combustion properties with the density and classes of selected wood species. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Relationships between the flammability properties of a given plant and its chances of survival after a fire still remain unknown. We hypothesize that the bark flammability of a tree reduces the potential for tree survival following surface fires, and that if tree resistance to fire is provided by a thick insulating bark, the latter must be few flammable. We tests, on subalpine tree species, the relationship between the flammability of bark and its insulating ability, identifies the biological traits that determine bark flammability, and assesses their relative susceptibility to surface fires from their bark properties. The experimental set of burning properties was analyzed by Principal Component Analysis to assess the bark flammability. Bark insulating ability was expressed by the critical time to cambium kill computed from bark thickness. Log-linear regressions indicated that bark flammability varies with the bark thickness and the density of wood under bark and that the most flammable barks have poor insulating ability. Susceptibility to surface fires increases from gymnosperm to angiosperm subalpine trees. The co-dominant subalpine species Larix decidua (Mill.) and Pinus cembra (L.) exhibit large differences in both flammability and insulating ability of the bark that should partly explain their contrasted responses to fires in the past.

The effects of fuel properties including ignitability, volatility, and compositions on operational range and combustion characteristics of premixed diesel combustion with various high volatility model fuels and an ordinary diesel fuel were examined in a direct injection diesel engine. The indicated mean effective pressure was limited by knocking with high-intake oxygen concentrations and by unstable combustion or significant increases in CO and total hydrocarbon emissions with low-intake oxygen concentrations regardless of fuels. The fuel volatility has little effect on the combustion characteristics and the stable operational range in premixed diesel combustion. With increasing octane number, the combustion phasing is retarded, and higher intake oxygen concentrations can be employed within the tolerance limits of rapid combustion, expanding the stable premixed diesel combustion indicated mean effective pressure range. The operational range of premixed diesel combustion with normal heptane and toluene blend fuels shifts to higher intake oxygen concentrations when compared with primary reference fuels with the same research octane numbers, showing lower ignition characteristics than primary reference fuel. The silent, low-NOx, and smokeless operation with high thermal efficiency was possible with both primary reference fuel and normal heptane and toluene blend fuel when the intake oxygen concentration is optimized corresponding to indicated mean effective pressure. [ABSTRACT FROM PUBLISHER]

Temperate ecosystems, for example British heathlands and moorlands, are predicted to experience an increase in severe summer drought and wildfire frequency over the next few decades. The development of fire ignition probability models is fundamental for developing fire-danger rating systems and predicting wildfire outbreaks. This work assessed the flammability properties of the fuel complex of British moorlands as a function of their moisture content under laboratory conditions. Specifically, we aimed to develop: (1) models of the probability of fire ignition in peat/litter fuel-beds (litter of four different plant species, Sphagnum moss and peat); (2) flammability properties in terms of ignitability, sustainability, consumability and combustibility of these peat/litter fuel-beds; (3) the probability of ignition in a canopy-layer of Calluna vulgaris (the most dominant heath/moor species in Britain) as a function of its dead-fuel proportion and moisture content; (4) the efficacy of standardized smouldering and flaming ignition sources in developing sustained ignitions. For this, a series of laboratory experiments simulating the fuel structure of moor vegetation were performed. The flammability properties in peat/litter fuel-beds were influenced strongly by the fuel moisture content. There were small differences in moisture thresholds for experiencing initial flaming ignitions (35–59%), however, the threshold for sustained ignitions (i.e. spreading a fixed distance from the ignition point) varied across a much wider range (19–55%). Litter/peat fuel-beds were classified into three groups: fuel-beds with high ignitability and combustibility, fuel-beds with high levels of sustainability, and fuel-beds with low levels in all flammability descriptors. The probability of ignition in the upper Calluna-vegetation layer was influenced by both the proportion of dead fuels and their moisture content, ranging from 19% to 35% of moisture as dead fuel proportion increased. Smouldering sources were more efficient in igniting peat/litter fuel-beds but in the Calluna-vegetation layer flaming sources performed better. This work can assist in improving the predictions of fire-rating systems implemented in British moorlands, by providing better warnings based on critical moisture thresholds for various fuel types. [Copyright &y& Elsevier]