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In gas turbines, confined highly turbulent flames unavoidably propagate in the vicinity of a relatively cool combustor liner, affecting both the local flame structure and global operation of the combustion system. In our recent work, we demonstrated, using simultaneous [OH] × [CH2O] planar laser-induced fluorescence (PLIF) and stereo-particle image velocimetry (stereo-PIV), that lean CH4/H2 flames at a high Karlovitz number can present a highly broken structure near wall, highlighted by a diffuse CH2O cloud, which suggests local quenching and incomplete oxidation. Such high Karlovitz numbers were achieved using an inclined plate, which substantially extended the lean flammability of the low swirl flames. Yet, how a cooled wall acting as a heat sink played a conducive role in stabilizing high Ka flames remains unanswered. In addition, the origin of the CH2O cloud is also unclear. Hence, in this work, we look to better understand the stabilization mechanisms for lean and ultralean flames on the same configuration, and how they may change with a parametric variation of plate incident angle, plate-nozzle distance, and bulk velocity up to the critical values that lead to flame blow off. The results show that the impinging swirling flow creates a low speed region that helps hold the flame, while the wall prevents mixing with ambient cold air. The production of diffuse CH2O, which indicates the occurrence of local quenching, is associated with a mean strain rate K beyond the extinction strain rate (ESR) Ke. For CH4 flames, most of the reaction zones reside within |K|Ke<; for 70% H2 flames at ϕ, the reaction zones are highly broken and scattered in a large area, where |K|Ke <8, the interspace of which is fully filled by CH2O. In other words, high H2 fraction flames appear to be more robust to persistent strain rate, thus extending their stability envelope. However, these flames can subsist as highly broken flames featuring strong incomplete combustion. [ABSTRACT FROM AUTHOR]

Experimental analyses and numerical simulations are carried out on a test case involving an heptane pool fire within a large under-ventilated environment. During the experiments, the temperature history at several locations within the room is monitored by means of thermocouples, and the fire radiative heat transfer estimated through a plate thermocouple. The experimental layout is then replicated numerically and tested using OpenFOAM CFD code. The study is a preliminary analysis performed for code validation purposes on a full-scale fire scenario. The results of the simulations are compared to the experimental results and critically analysed, finding a reasonable agreement overall. Critical issues in fire modelling are also highlighted. In fact, due to the problem complexity and the limitations of the numerical models available some important aspect that can significantly influence the outcome of the simulations must be calibrated a posteriori, somewhat limiting the general predictive applicability of the fire models. Primarily, these are the heat release rate history, the combustion efficiency, and, to a lesser extent, the convective heat transfer boundary condition at the wall. [ABSTRACT FROM AUTHOR]

A series of trials were conducted to investigate the repeatability of furniture-scale calorimetry experiments. Twenty-five identical upholstered chairs were ignited under the same experimental conditions. Experimental results of heat release rate (HRR), mass loss rate (MLR), and emission yields (CO, CO2, N2O, NO, CH4, HCN) are presented. Discrepancies were observed between the time resolved evolution of the various recorded data. However the development of each fire was observed to be tied to common events. By accounting for these events, a more consistent representation of the burning behaviour can be expressed. Each experiment displayed distinct burning regimes (i.e., pyrolysis, flaming, and smouldering) which were identified through visual observation and through analysing the emission data. Some species yields were found to be approximately constant over some burning regimes (e.g., CO2 yield over the flaming regime) while others displayed highly transient behaviour (e.g., CO yield was found to be burning regime dependent). Results from upholstered furniture scale experiments, including HRR and emission yields, are commonly used in various engineering applications; this study lends insight into the variability that can be observed for such data and the implications in applying this data in further analysis. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of the unsteady heat release rate response of industrially relevant axisymmetric premixed flames to harmonic velocity perturbations. The heat release rate response, quantified using the flame transfer function (FTF) definition, is measured from an acoustically forced swirl burner under perfectly premixed conditions. To understand the features of the measured FTF, a physics-based analytical model is developed in this study. To describe the heat release rate dynamics, a model for the flame spatiotemporal response is derived in the linear limit using the G-equation formulation. Inputs to the flame response model are selected to be consistent with values observed in the corresponding industrial burner, based on experimental and numerical studies. The relative contributions of acoustic and convecting vortical disturbances on specific features of the FTF are explored in this study. The results highlight the importance of capturing the appropriate disturbance velocity field as an input to the flame response model for accurate FTF predictions. [ABSTRACT FROM AUTHOR]

AbstractContributing to the confinement safety evaluation of glove boxes (GBs) connected to high-efficiency particle air filters for radioactive materials under fire accidents, combustion tests of a flammable polymer, i.e., polymethyl methacrylate (PMMA), and a flame retardant polymer, i.e., polycarbonate (PC), as typical GB panel resins have been conducted with an engineering-scale combustion apparatus. Combustion properties such as the mass loss rate (MLR) and the heat release rate (HRR) of PMMA and PC were investigated in the combustion tests. From our results, the relationships of MLR and HRR to the surface area of the plate type of PMMA and PC were deduced. [ABSTRACT FROM AUTHOR]

In this work, an experimental investigation is performed to study the flame height and air entrainment of 0.2 m n-heptane double pool fires (DPF) with various separation distances (S). The results show an inverse relationship between the flame height and air entrainment with S. The increase in the flame height of DPF with a decrease in the air entrainment is more than half of the standalone fire. A correlation is developed to predict the flame height of DPF considering the nondimensional air entrainment and heat release rate. Also, a correlation is developed between the nondimensional air entrainment and S. [ABSTRACT FROM AUTHOR]

Ammonia is a carbon-free, promising fuel for hydrogen carriers. It is a liquid fuel under low-pressure conditions (8.62 bars) and can be easily stored. Many researchers have tried to apply it in engines because there are no carbon dioxide emissions when combusting it. However, ammonia is a low cetane number fuel and is difficult to ignite. It can be used in a dual fuel mode in compression ignition (CI) engines, i.e., a fuel such as diesel, n-heptane, dimethyl ether, hydrogen etc., is used as a pilot fuel to ignite the ammonia. In this work, n-heptane was used as the pilot fuel and ammonia was used as the primary fuel in a light-duty CI engine. The engine's heat release rate (HRR), cylinder pressure, ignition delay and indicated efficiency were investigated experimentally at 80 %, 89 %, 95 % and 98 % ammonia fuel energy proportion. In order to investigate the ignition and combustion characteristics of the dual fuel engine, a multi-zone combustion model for n-heptane and a flame propagation model for the ammonia fuel were developed. In this work, it is found that the combustion process of n-heptane/ammonia can be simulated in most cases by a multi-zone evaporative combustion model combined with a flame propagation model. This work also found that the ignition performance of n-heptane is more affected by the long chemical ignition delay. Eventually, it was found that the more minor the discrepancy between the simulated and experimental ignition delays, the more insignificant the discrepancy between the simulated heat release rates and cylinder pressures and the experimental ones. The HRR, cylinder pressure, physical and chemical ignition delays and indicated efficiency of the engine were then simulated. The simulation showed good agreement with experimental results for the 89 %, 95 % and 98 % ammonia fuel energy proportion cases. The simulated physical ignition delay was 1.45–2.37 CA deg, the chemical ignition delay was 7.21–8.88 CA deg, and the indicated efficiency was 39.84%–42.80 % (for the three cases with 89 %, 95 % and 98 % ammonia fuel energy proportions). A detailed analysis of each parameter was conducted. • The n-heptane multi-zone model and flame propagation model for ammonia were jointly developed. • Combined theoretical and experimental analysis of combustion processes. • Analysis of the heat release rate and cylinder pressure of ammonia fuels with different energy proportions. • Prediction deviation in ignition delay largely determines prediction deviation in HHR and cylinder pressure. • Chemical ignition delay dominates the ignition performance. [ABSTRACT FROM AUTHOR]

In diesel engines, emission formation inside the combustion chamber is a complex phenomenon. The combustion events inside the chamber occur in microseconds, affecting the overall engine performance and emissions characteristics. This study opted for using computational fluid dynamics (CFD) to investigate the combustion patterns and how these events affect nitrogen oxide (NOx) emissions. In this study, a diesel engine model with a flat combustion chamber (FCC) was developed for the simulation. The simulation result of the heat release rate (HRR) and cylinder pressure was validated with the experimental test data (the engine test was conducted at 1500 rpm at full load conditions). The validated model and its respective boundary conditions were used to investigate the effect of modified combustion chamber profiles on NOx emissions. Modified chambers, such as a bathtub combustion chamber (BTCC) and a shallow depth chamber (SCC), were developed, and their combustion events were analysed with respect to the FCC. This study revealed that combustion events such as fuel distribution, unburnt mass fractions, temperature and turbulent zones directly impact NOx emissions. The modified chambers controlled the spread of combustion and provided better fuel distribution, improving engine performance and combustion rates. The SCC (63.2 bar) showed peak pressure rates compared to the FCC (63.02 bar) and BTCC (62.72 bar). This study concluded that the SCC showed better results than other chambers. This study further recommends conducting lean fuel mixture combustion with chamber modifications and optimising fuel spray, such as by adjusting the fuel injection profile, spray angle and injection timing, which has a better tendency to create complete combustion. [ABSTRACT FROM AUTHOR]

This research comprises a thorough examination of the transesterification of discarded and non-edible Acacia seed oil (ABD) in order to fuel the diesel engine. The research also looks at the emission configurations of a four-stroke diesel examination engine. ABD (10% and 20% vol. respectively referred as ABD10 and ABD20) blended with diesel fuels were used to calculate the emission patterns under varying conditions. All ABD blends exhibited lower smoke opacity, HC and CO emissions than diesel, though a minor escalation in NOx emissions. [ABSTRACT FROM AUTHOR]

This study delved into the combustion properties of combined glulam bonded using polyurethane (PUR) and resorcinol-phenol-formaldehyde (RPF) adhesives. The experiment involved three distinct wood species, namely, spruce, alder, and beech, which were combined in homogeneous, non-homogeneous symmetrical, and non-homogeneous asymmetrical arrangements. These species were selected to represent a spectrum, namely, softwood (spruce), low-density hardwood (alder), and high-density hardwood (beech). The varying combinations of wood species illustrate potential compositions within structural elements, aiming to optimize mechanical bending resistance. Various parameters were measured during combustion, namely, the heat release rate (HRR), peak heat release rate (pHRR), mass loss rate (MLR), average rate of heat emission (ARHE), peak average rate of heat emission (MARHE), time to ignition (TTI), and effective heat of combustion (EHC). The findings indicate that incorporating beech wood into the composite glulam resulted in an increase in heat release, significantly altering the burning characteristics, which was particularly evident at the second peak. Conversely, the use of spruce wood exhibited the lowest heat release rate. Alder wood, when subjected to heat flux at the glued joint, displayed the highest heat emission, aligning with the results for EHC and MARHE. This observation suggests that wood species prone to early thermal decomposition emit more heat within a shorter duration. The time to ignition (TTI) was consistent, occurring between the first and second minute across all tested wood species and combinations. Notably, when subjected to heat flux, the glulam samples bonded with PUR adhesive experienced complete delamination of the initial two glued joints, whereas those bonded with RPF adhesive exhibited only partial delamination. [ABSTRACT FROM AUTHOR]

Electrical cables are one of the main fire hazards in nuclear power plants (NPPs) and in many other industrial sectors. To assess the potential damages of the cable fires, models are required to forecast the fire spread over multiple cable trays and the resulting heat release rate. A new test device, called CISCCO, was developed to conduct flame spread experiments on a preheated horizontal cable layer to support the development and validation of the models. The characteristics of the CISCCO device are first presented before the description of four series of experiments that first investigated the temperature dependence of the flame spread velocity. The series involved a cable layer composed of either a polyvinyl chloride (PVC)-based cable, named PVC cable or a halogen free flame retardant (HFFR) poly(ethylene–vinyl acetate)/polyethylene-based cable, labelled HFFR cable. Temperature measurements performed in the solid phase (cable outer sheath) and in the gas phase (above the cable layer) allowed to assess the preheated cable layer temperature and the flame spread velocity. A first attempt of flame heat flux measurements was also conducted in this work. All series highlighted a temperature dependence of the flame spread velocity according to experimental power laws. The flame spread velocities were measured higher for the PVC cable (0 to 5.5 mm/s) than for the HFFR cable (0 to 1.5 mm/s) while the related preheated cable temperatures suitable for spreading were measured lower for the former (170 to 250°C) than for the latter (280 to 370°C). Finally, one of the four test series that used the PVC cable and implemented heat release rate measurements, revealed that the cable fire growth rate is also temperature dependent according to a power law and is linearly correlated to the flame spread velocity. [ABSTRACT FROM AUTHOR]

This paper considers the fire risk associated with luggage in trains from an experimental point of view. After a review of existing data, it was decided to test medium isolated suitcases, large isolated suitcases, two medium and one large suitcases in a rack, and two medium and one large suitcases in a confined rack, representative of luggage stacked next to the entrance doors of coaches in high-speed trains. Heat release rates were estimated by three methods: mass loss measurement, dilution calorimetry and oxygen consumption calorimetry. Measured peak heat release rates are of order 250 kW for medium size suitcases and 400 kW for large suitcase. The sum of two medium and one large suitcase would therefore be in the order of 900 kW. However, rack tests with two medium and one large suitcase gave values in the order of 1300 kW for an open rack and 2100 kW for a confined rack. This shows a strong effect of rack geometry and confinement. The concentrations of carbon monoxide and carbon dioxide are also measured, as is the total amount of hydrogen cyanide released in each test. An empirical fire curve is proposed taking into account the effect of confinement. [ABSTRACT FROM AUTHOR]

Fire related to household items poses a threat to life safety and residential property. In this study, the fire characteristics of single household items are established as a fundamental of risk assessment for performance-based design. Information on peak heat release rate, time to peak heat release rate and total heat released are collected from full-scale fire experiments in the literature. The household items are individually classified by their dimension: Television, Chair, Table, Armchair, Cabinet and Bed for statistical and probability distribution analyses. The analysis generally exhibits an increasing trend in the fire characteristics against the item dimension increment. A linear fit with a strong correlation value is achieved for the peak heat release rate and total heat released, while a weak correlation is observed to linearly fit the time to peak heat release rate. The ranked order of fitting statistics suggests Gamma, Log-Normal and Logistic distribution as the best-fit distribution respectively for the peak heat release rate, time to peak heat release rate and total heat released. The distribution parameters are provided and can be used for probabilistic fire assessment related to household items. [ABSTRACT FROM AUTHOR]

The fire behaviour and smoke behaviour of a fire in an underground mine will be largely dictated by the heat release rate of the fire. The heat release rate per unit area is generally the output from small-scale fire experiments and can be applied for larger objects with varying surface area. This paper studies the impact of varying heat release rate per unit area for fires in materials and substances typically found underground. Data from earlier fire experiments were analysed and discussed, and several different heat release rate curves and flame spread velocities for various fuel components were developed and discussed. It was found that the hydraulic hose presented the highest peak heat release rate per unit area of the solid fuel items, followed by the low-voltage cable, cab interior, and tyre in descending order. The increase in the peak heat release rate was highest for the highest incident heat flux levels, representative for scenarios underneath a mining vehicle. The heat release rate per unit area of pool fires underneath a vehicle is significantly higher than a corresponding free burning case - attributed to the higher incident heat flux – but a gravel surface underneath a pool fire will reduce the heat release rate considerably. Line fires in larger bundles of electrical cables were modelled and found to attain the peak flame spread velocity more rapidly compared with a fire in hydraulic hoses. This was caused by the higher heat release rate of the initial fire and ignited segments in the electrical cable case. [ABSTRACT FROM AUTHOR]

In the unfortunate event of a fire, within the context of the evolution of façade fires, with a specific focus on the utilization of polystyrene thermal insulation (external thermal insulation composite system façades—ETICS façades), this study delves into the investigation of fires ignited by containers containing plastic bottles. Through an examination of the fluctuating temperatures within the affected room and its adjacent areas, as well as an assessment of the fire's impact on polystyrene thermal insulation, this paper underscores the significance of incorporating non-combustible barriers into the building's thermal insulation system. The tests conducted revealed that the temperature inside the room reached a maximum of 1100 °C, subsequently decreasing to 800 °C at a height of 2.5 m and approximately 400 °C at a height of 5 m. For this research, two 1100-L containers of household waste were employed, each weighing 45.5 kg and possessing a gross calorific value of 46.97 MJ/kg, with 10.7 kg of PET bottles inside, characterized by a higher calorific value of 23.90 MJ/kg as the source of the fire. Heat release rate highest values were obtained between 11 and 17 min, with a maximum value of 4919 kW. Thus, even in the absence of specific legislation, this study emphasizes the imperative need to establish safety distances for the storage of household waste away from the building's façade to mitigate the risk of fire propagation, particularly in relation to materials such as polystyrene thermal insulation. Furthermore, in certain situations, extensive fire experiments on a grand scale, like the one undertaken in this research, hold a crucial position in confirming numerical findings for global researchers. This process assures the reliability and real-world usefulness of fire safety studies through the experimental outcomes presented in this investigation. [ABSTRACT FROM AUTHOR]

Thermal runaway (TR) is one of the main concerns in battery application due to their hazard level for the people and environment. In this work, the thermal runaway behaviors of lithium-ion batteries (LIBs) are investigated in ambient nitrogen (N2) concentration from 78 to 100%. Several parameters are measured to assess the fire hazards of LIBs, including battery surface temperature (Tsurf), ignition time (tig), total mass loss, heat release rate, and total heat release. The experimental results show that the risk of TR increases with the increase in state of charge. For different N2 concentrations, the addition of N2 will reduce oxygen (O2) concentration and weaken internal reactions, while excessive N2 will react with lithium-ion inside the LIBs. 82% N2 concentration shows the greatest inhibition effect on TR, where the values of battery surface temperature, total mass loss, heat release rate, and the total heat release reach the minimum ones. [ABSTRACT FROM AUTHOR]

Once fires occur unexpectedly at the oil-hydrogen integrated refueling stations, there is a high likelihood that they will escalate into a coupled fire, resulting in unpredictable casualties and property losses. In this work, experiments on coupled fire induced by hydrogen jet flame and a heptane pool flame were conducted with different nozzle diameters and release pressures. It has been found that there is a critical diameter above which the hydrogen jet can be ignited instantly. This critical diameter is determined by the release pressure and the location of the pool flame. The heat release rate is greater than that of the single pool flame, and it reaches its highest point at 0.2 MPa. Compared to a single fire, the height of the flame decreases while the length of the flame increases, a prediction model is proposed for the dimensionless flame length and width, taking into account the ratio of the heat release rate of the hydrogen jet flame to the heat release rate of the pool flame. The temperature of the coupled fire reaches its highest point at 0.2 MPa and increases as the nozzle diameter. And it decreases with the increase in the distance when Y= 0 m. However, it increases with the increase of the distance when Y= 0.05 m due to the inclination of the flame. [ABSTRACT FROM AUTHOR]

Measuring flame lengths and areas from turbulent flame flares developing from lithium-ion battery failures is complex due to the varying directions of the flares, the thin flame zone, the spatially and temporally rapid changes of the thermal runaway event, as well as the hazardous nature of the event. This paper reports a novel methodology for measuring heat release rate from flame flares resulting from thermal runaway of electric vehicle lithium-ion modules comprising eight 56.3Ah lithium nickel manganese cobalt (NMC) pouch cells using digital cameras and a newly developed numerical code to process the distortion of the flame size based on distance, direction, and shape. The model is tested with a set of experiments using lithium-ion battery packs and validated with a reference set of measurements using calibration boxes, a method commonly used in the reconstruction of flame areas. The experiments showed that the effect of calibration is large, and thus digital imaging without the appropriate calibration can give very large errors in measurement of flames. The combined imaging and processing method proposed in this work allows the determination of heat release rates from lithium-ion battery packs, one of the most challenging variables to quantify during the failure of a battery pack outside the laboratory. In the example experiment that this method was applied to, almost double the heat released was accounted for, meaning 50% of the total heat released would not have been accounted for without this image processing method. [ABSTRACT FROM AUTHOR]

Polymers are widely employed in many areas, e.g. transport, packaging, electronic devices, etcetera. Among them, acrylonitrile–butadiene–styrene (ABS) is one of the most employed polymers due to its mechanical properties, its ease to mechanize and recyclability. Nevertheless, according to the fire properties, ABS behaviour is usually worse than other polymers, therefore, they have to be upgraded with flame retardant additives. To characterize the fire behaviour of a certain material is necessary to address several typology of tests, providing relevant properties such as thermal conductivity, flammability and heat released. However, researchers may not always be able to run all tests due to the lack of apparatus or samples. Therefore, it is necessary to seek bibliographic sources. As one might expect, for a given material, the property values should be similar, regardless of who performs the test. However, sometimes slightly different results are obtained, which may be due to different causes, such as differences in test set-up and in material composition/manufacture. These differences in properties may lead researcher to doubt which data to use. This paper presents the results of different types of tests using neat ABS polymer. Additionally, these results are compared with the data from literature, discussing the similarities/differences and offering a more comprehensive characterization of ABS. The laboratory techniques included in this work are: thermogravimetric analysis, differential scanning calorimetry, laser flash analysis, smoke density, cone calorimeter, fire propagation and flammability. [ABSTRACT FROM AUTHOR]

The current study presents research investigations and developments related to the homogeneous charge compression ignition (HCCI) engine. Research investigations and recent advances, including the role of various operating conditions on HCCI engine combustion phenomena, emissions, and performance, are discussed. There is growing research interest in investigating HCCI engines with diesel fuel to study combustion, emissions, and performance characteristics due to their association with low NOx emissions. In the published literature, research investigations are also conducted with different fuels ranging from biomass to diesel to gasoline in the HCCI engine showing its capability for utilizing various fuels in coming years. The challenges associated with HCCI combustion are reviewed, and the details of excessive carbon monoxide and unburnt hydrocarbon emissions are discussed. The major parameters affecting the hydrogen addition in HCCI diesel engines are also discussed. Overall, adding hydrogen to a diesel‐fueled HCCI engine improves combustion phasing and can potentially increase thermal efficiency while lowering emissions. In addition, the strength, weaknesses, opportunities, and threat analysis is provided and discussed thoroughly. [ABSTRACT FROM AUTHOR]

The current literature reports a few papers regarding the prediction of heat release rate of a diesel engine fuelled with n-octanol blends using numerical methods. To address this gap, the main objective of the presented study is to derive correlations for estimating the variation in heat release rate of a diesel engine fuelled with diesel fuel and diesel fuelbiodiesel- n-octanol blends. For this purpose, three different ternary blends were prepared by varying the n-octanol concentration to 6% (OCT6), 8% (OCT8), and 10% (OCT10) by volume. The estimation of heat release rate was accomplished using the least-squares regression (sine, piecewise, and rational equations) and the function approximation (Padé approximation) methods. The ignition delay and peak heat release rate increased by 3.8462%, 5.9501% for OCT6; 7.6923%, 3.7125% for OCT8; and 8.9744%, 3.0755% for OCT10, respectively, compared to diesel fuel. The peak cylinder pressure of OCT6 and OCT8 was observed to be higher by 2.4378% and 1.3982%, respectively, whereas that of OCT10 was found to be lower by 1.9458%, compared to diesel fuel. Compared to the others, the suggested rational equation qualitatively and quantitatively achieved the best correlation with all experimental heat release rate data measured by both the author and some other authors. [ABSTRACT FROM AUTHOR]

Transparent wood is a modern bio-renewable material with great potential for both science and industrial applications. However, the fire hazard of transparent wood is still almost unexplored. This study aims to investigate the impact of pristine basswood modification to epoxy-based transparent wood on the fire hazard and to train neural networks for the prediction of heat release rate from mass loss rate of pristine basswood, epoxy-based transparent wood, and epoxy resin. Transparent wood was prepared by lignin modification in pristine small-leaved basswood (Tilia cordata Mill.) and subsequent vacuum infiltration by epoxy resin. The fire hazard of the samples was determined by the cone calorimeter at four heat fluxes of 20–50 kW m−2. The fire hazard of investigated materials was compared based on the critical heat flux, ignition temperature, heat release rate, effective heat of combustion and time to flashover. Transparent wood showed higher resistance to ignition (higher critical heat flux and ignition temperature) than pristine wood. However, other parameters (heat release rate and effective heat of combustion) were higher (worse) and the time to flashover was lower (worse) for transparent wood than for pristine wood. Trained neural networks for predicting heat release rate from the mass loss rate of wood (both pristine and transparent) and epoxy resin showed coefficients of determination from 0.70 to 0.92. Trained neural networks with a coefficient of determinations above 0.90 are usable for low-cost heat release rate measurements in both science and industrial applications. [ABSTRACT FROM AUTHOR]

Cables are one of the most important fire loads in nuclear power plants. It is therefore important to understand their fire behaviour and to predict their heat release rate curve. Electricité de France carried out a series of full-scale vertical cable tray fire experiments. Relevant measurement systems were used. The aim of this article is to give an overview of these experiments and their main results. Important aspects of the fire behaviour are discussed and compared with the literature. In addition, two models, namely the FLASH-CAT model and the ISO 18195 vertical cable tray model, are compared to the experiments and their ability to predict the heat release rate profile is discussed. The models are also compared with other real-scale experiments available in the literature. The ISO 18195 model shows good agreement with the different experiments for the heat release rate profile. The FLASH-CAT model obtains reasonable conservative results for the maximum heat release rate. However, the model significantly overestimates the growth rate in all the tests. [ABSTRACT FROM AUTHOR]

In response to the growing demand for higher energy density in various applications, large-format batteries have gained popularity. However, the larger size of these batteries also increases their exposed area, which may lead to more severe thermal events. This study aims to understand the influence of incident heat flux on the occurrence and progression patterns of fires in large-format lithium-ion batteries. Two representative large-format lithium-ion batteries, 38 Ah LiNi 0.3 Co 0.3 Mn 0.3 O 2 prismatic cell and 78 Ah LiNi 0.8 Co 0.1 Mn 0.1 O 2 pouch cell, were investigated. To evaluate the thermal hazard to the environment, the heat release rates (HRR) of the lithium-ion battery fire were measured under incident heat fluxes ranging from 10 to 50 kW∙m−2, using the oxygen consumption principle. The results highlight significant differences in thermal runaway and fire development between the 38 Ah and 78 Ah cells, attributable to variations in structure and materials, and scale effect. The 38 Ah cell exhibited an evident venting stage, characterized by an unignited jet on the verge of ignition, followed by a transition from momentum-driven jet fire to buoyancy-driven jet fire. In contrast, the 78 Ah cell experienced direct ignition, accompanied by strong air entrainment, overflow flame, and flame sinking phenomena as the fire progressed. Notably, unlike the 38 Ah cell, the peak HRR, THR, and burning time of the 78 Ah cell were minimally sensitivity to the incident heat flux. Furthermore, a generalized relationship model between the incident heat flux and the ignition time was established and validated based on the energy conservation equation during the ignition stage of the cell. This model enhances our understanding of the interplay between incident heat flux and ignition time, contributing to the development of strategies for fire prevention and mitigation in large-format lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Physical experiments and computer simulations are commonly employed to characterize and understand fire behaviour under different conditions. Many medium- to large-scale physical experiments utilize standardized wood cribs as the fire load, while corresponding computer simulations require physical and combustion properties of such fire loads. The design of physical experiments and accuracy of computational models depend heavily on the underlying combustion models. The current study proposes an improved two-step combustion model for soft and hard wood based on physical characterization of different wood samples. Two different types of wood, i.e. softwood and hardwood were characterized using cone calorimeter. Total of six cone tests were performed under irradiation levels of 30, 50 and 75 kW m−2 for each wood sample. Thermogravimetry analysis (TGA) of wood samples was carried out to estimate the combustion kinetic parameters (through different estimation methods) like activation energy, pre-exponential factor, and reaction order for numerical simulation of cone calorimeter tests. The kinetic parameters estimated through the Kissinger–Akahira–Sunose integral method were utilized to perform computer simulation of TGA and cone calorimeter in fire dynamic simulator (FDS) using one-step and two-step combustion models. Thermal degradation temperatures of both the types of wood were observed to be between of 200 and 500 ℃. During whole pyrolysis process, softwood was observed to possess larger activation energy than that of hardwood. The reaction models for softwood and hardwood were found to be diffusion type with reaction order of 2–3. TGA simulation results obtained by the two-step simulation approach were found to be better than that of one-step simulation approach. In case of cone calorimeter simulations, the two-step simulation approach yielded better prediction of heat release rate and time to ignition as compared to that of the one-step simulation approach. It is expected that the present study would be helpful in large-scale FDS fire simulation involving softwood and hardwood. [ABSTRACT FROM AUTHOR]

A fire whirl, a unique fire behavior, occurs when a vertical vortex of flames skyrockets due to specific surrounding temperatures and thermal gradient conditions during a fire. Compared with conventional fire plumes, fire whirls exhibit a higher air entrainment rate, tangential velocity, and axial velocity, thus presenting greater risks and destructive capabilities. Thus, studying the combustion characteristics of fire whirls becomes necessary. This experiment employed a small-scale, fixed-frame fire whirl generator. We investigated how varying air-inlet widths and fuel pan diameters influence the fire whirl's combustion characteristics. Experimental images indicated a negative correlation between the fire whirl's flame height and the air-inlet width, and a positive correlation with the fuel pan diameter. Our findings showed that the burning rate of the fire whirl during the quasi-steady-state combustion phase initially increased and then decreased as the air-inlet width expanded, peaking at a width of 7 cm. The data demonstrated a corresponding power-law relationship between the fire whirl's dimensionless flame height and excess temperature. Ultimately, our results indicated a positive correlation between the 2/5 power of the fire whirl's dimensionless heat release rate and the dimensionless flame height. The ratios of maximum to mean flame height and mean to continuous flame height are 1.35 and 1.5, respectively. Significantly, these ratios remain unaffected by the air-inlet width, fuel pan diameter, environmental temperature, and heat release rate. [ABSTRACT FROM AUTHOR]

The effect of the water addition into the intake air (WAIA) on cylinder pressure, temperature, heat release rate (HRR), combustion duration (CD), and energy balance in an automotive diesel engine have been investigated experimentally. Also, an empirical correlation has been developed for estimating CD using the HRR. This relation has been developed by applying the multiple curve fitting method, taking into account experimental results for different water ratios such as (2, 4, 6, 8, and 10) %, different engine loads, and different engine speeds such as (2000, 2500, 3000, 3500, and 4000) rpms. The test results showed that cylinder pressure values generally increased at (2000, 2500, and 3500) rpm, but they decreased at (3000 and 4000) rpm for all of the selected water ratios. Also, maximum cylinder temperature values have occurred at crank angles farther from TDC for WAIA. Cylinder temperature values mostly decreased at (2000, 2500, and 3000) rpms, but they generally increased at (3500 and 4000) rpms for WAIA. Also, maximum cylinder temperature values were occurred at crank angles farther from TDC for WAIA. HRR values generally decreased at (2000, 2500, 3500, and 4000) rpms, but they generally increased at 3000 rpm. It has been determined that the CDs were generally shortened at all of the engine speeds under full loads with water addition. CD values for NDF and (2.42, 4.22, 5.95, 8.32, 9.46) % water ratios have been determined as (13.10, 12.96, 12.93, 12.68, 12.95, and 13.576) °CA, respectively, at 2000 rpm. The effective power values according to the chemical energy of the fuel generally decrease with WAIA at 2000 rpm. However, the effective power values according to the chemical energy of the fuel increase for high WRs at 4000 rpm. [ABSTRACT FROM AUTHOR]

A large amount of storage may cause large-scale fire or explosion accidents due to the potential fire risk of lithium-ion batteries, which poses a great threat to the safety of personnel and property. In this study, the fire model of an individual cell is established according to the experimental data and the relevant parameters of thermal runaway simulation of large capacity battery are determined. The battery pack model is established according to the real setting of a warehouse. The fire characteristics of the battery pack spreading around in the warehouse environment are studied. The results show that the fire of lithium-ion batteries is preferentially diffused to the upper battery pack in the warehouse environment, and spread to the upper battery pack 19 s after the initial battery thermal runaway. The fire propagation of the horizontal battery pack is greatly affected by the distance. The farther the battery string is from the thermal runaway battery, the later the fire propagation battery string occurs. Furthermore, the role and effect of battery pack spacing, fire warning and automatic sprinkler system in fire are provided, so as to carry out better research on the storage safety of lithium-ion battery warehouses. [ABSTRACT FROM AUTHOR]

Prediction of flammability characteristics of materials is possible via molar group contribution calculations. However, in most industries raw material composition is unknown and micro combustion calorimeter (MCC) is applied for measuring heat release rate (HRR) and calculates flammability characteristics. This work predicts HRR and flammability characteristics for complex formulations based on HRR from a reduced number of the individual constituents, all with unknown chemical composition. Water-based paints (> 15 components) with and without chemical interaction during thermal decomposition were predicted via linear combinations of component HRR and validated against experimental MCC data. Prediction of HRR and flammability characteristics was successful, and the obvious breakdown for reactive mixtures was confirmed. These results can be utilized as screening tool for flammability characteristics and identity component interaction in mixtures—which considerably enhances the strength of MCC in development of new materials. [ABSTRACT FROM AUTHOR]

The influence of iron nanoparticle (INP) addition (75 ppm) and hydrogen enrichment (10 lpm) with waste cooking palm biodiesel blend (WCB) on a CRDI diesel engine is evaluated. A blend of 20% WCB and 80% diesel is used, and the dosing level of INP has been kept at 75 ppm, which has been decided based on the oxygen content of biodiesel. Results indicate that the combination of H 2 enrichment and INP addition improves the BTE and BSFC of biodiesel blends as that of diesel. A maximum improvement of BTE of 7.1% than that of diesel is obtained at 90% loading. The combined impact of better hydrogen combustion characteristics and improved air-fuel mixing with nanoparticles reduces CO and HC emissions by 37.5% and 41.8%, respectively, for the WCB fuel sample. However, NO X emission shows an elevation of 27.4% compared to diesel. Combustion parameters, namely ICP (80.1 bar) and HRR (89.5 J/˚CA) indicate an improvement of 5.3% and 6.7% compared to diesel for WCB + INP + H 2. This is owing to the combination of hydrogen's rapid flame speed and INP-added biodiesel's increased thermal conductivity. • Cumulative impact of hydrogen enrichment and nanoparticle addition is evaluated. • Hydrogen is introduced at 10 lpm with 75 ppm of iron nanoparticle concentration. • An improvement in BTE and BSFC are obtained by 7.05% and 6.45%, respectively. • A significant reduction in HC and CO emissions is obtained. • Higher ICP and HRR are observed with the inclusion of INP. [ABSTRACT FROM AUTHOR]

Semi-solid lithium-ion flow battery (SSLFB) is a promising candidate in the field of large-scale energy storage. However, as a key component of SSLFB, the slurry presents a great fire hazard due to the extremely flammable electrolyte content in the slurry as high as 70 wt%–95 wt%. To evaluate the fire risk of SSFLB, the combustion experiments of electrolyte and slurry were conducted using cone calorimeter, and the critical fire parameters such as heat release rate (HRR), mass loss rate (MLR), and gas production were analyzed. This study firstly compared the combustion characteristics of electrolytes with the addition of different lithium salts (LiPF6 and LiTFSI). The results showed that the peak HRR (pHRR) and peak MLR (pMLR) of LiTFSI-based electrolyte were reduced by 30.3% and 33.2%, respectively, compared with LiPF6-based electrolyte. Also, LiTFSI-based electrolyte possessed a relatively lower toxic hazard. Overall, LiTFSI could reduce the fire hazard of the electrolyte compared with LiPF6. Then, the combustion behaviour of slurries containing different electrode materials (Li4Ti5O12, LiNi0.8Co0.1Mn0.1O2, LiFePO4, and Graphite) was investigated. It was observed that the splashing occurred in the early stage combustion of slurries. The splashing of S-LTO and S-LFP was relatively violent, while only sporadic splashing occurred for S-NCM and S-graphite. Based on the pHRR and pMLR test results, the order of fire risk of the four slurries is determined as S-LTO > S-LFP > S-NCM > S-Graphite. The pHRR and pMLR of slurries other than S-LTO are lower than that of electrolyte, thus their fire risk is lower than electrolyte. The results of this study can provide a reference for the fire hazard evaluation and safety improvement of the SSFLB system. [ABSTRACT FROM AUTHOR]

Energy demand increases day by day due to the present technological scenario and fossil fuels are also depleting gradually. Therefore, the necessity came into the researchers to identify an alternative renewable resource for compensating the energy demand. The biodiesel appeared to the researchers as an important resource due to its characteristics and ability to compensate for the energy demand. However, some additional improvements are required for the efficient performance of the biodiesel, such improvement is achievable by the blending of an efficient additive with the biodiesel. The present study predominantly focuses to investigate the performance of the biodiesel with two different additives such as cerium oxide nanoparticles and ethanol. The neem (Azadirachta indica) oil has been selected as feed stock. The cerium oxide nanoparticles are prepared using the green synthesis process. Four various fuel samples are prepared to examine the effect of additives, (i) PB (pure biodiesel), (ii) BCe (PB+100 ppm CeO2), (iii) BE (90% biodiesel+10% ethanol) and (iv) BCeE (90% biodiesel+100 ppm CeO2+10% ethanol). From the experimentation, it is observed that the fuel BCeE achieves the better performance due to the oxygen buffering characteristics and improvement in the atomization by the additives. [ABSTRACT FROM AUTHOR]

This study numerically analyses the effects of chamber modifications to investigate the improvement of in-cylinder combustion characteristics of the diesel engine using a computational fluid dynamics (CFD) approach. Five different modified chambers, namely, the double swirl combustion chamber (DSCC), bathtub combustion chamber (BTCC), double toroidal re-entrant combustion chamber (DTRCC), shallow depth combustion chamber (SCC), and stepped bowl combustion chamber (SBCC) were developed and compared with a reference flat combustion chamber (FCC). The effects of chamber modifications on temperature formation, velocity distribution, injection profiles, and in-cylinder turbulent motions (swirl and tumble ratio) were investigated. During the compression stroke, near top dead centre, the SCC showed a peak temperature of 970 K, followed by the FCC (968 K), SBCC (967 K), and DTRCC (748 K to 815 K). The DSCC and the SCC showed a high swirl ratio above 0.6, whereas the DTRCC and the BTCC showed a high tumble ratio of approximately 0.4. This study found that the SCC, BTCC, and DSCC have better combustion rates than the FCC in terms of temperature, heat release rate, and velocity distribution. However, the DTRCC showed poor temperature formation rates and rapid heat release rates (approx. 150 J/°CA), which can lead to rapid combustion and knocking tendencies. In conclusion, the DSCC and the SCC showed better combustion rates than the other chambers. In addition, turbulent motions inside the chambers avoided combustion in crevice regions. This study recommends avoiding chambers with wider bowls in order to prevent uneven combustion across the cylinder. Furthermore, split bowls such as the DSCC, along with adjusted injection rates, can provide better results in terms of combustion. [ABSTRACT FROM AUTHOR]

In order to explore the thermal safety of lithium ion batteries (LIBs), a series of thermal runaway tests for single 32,650 LIB with different state of charges (SOC) and double 32,650 LIBs with different spacings from 0 to 2 D (D is 32 mm) are conducted in this work. It is clearly shown that the increasing SOC decreases the onset and duration time of the jet fire stages, increasing the mass loss and flame area in the jet fire stages. With the spacing decreases, the thermal effect of the flames on the LIBs is enhanced, which decreases the onset and duration time of the jet fire stages, increasing the mass loss and strengthening the combustion in the two second jet fire stages. In addition, according to the flame surface area and mass loss rate (MLR), the heat of combustion of LIB is estimated as Δ H c = 8.21 kJ g - 1 , and a simplified model is derived to predict the heat release rate (HRR) of LIBs. The above results provide a theoretical foundation for quantitative assessment of the fire risk of the LIBs. [ABSTRACT FROM AUTHOR]

In the present study, Reynolds-Averaged Navier-Stokes simulations together with a novel flamelet generated manifold (FGM) hybrid combustion model incorporating preferential diffusion effects is utilised for the investigation of a hydrogen-blended diesel-hydrogen dual-fuel engine combustion process with high hydrogen energy share. The FGM hybrid combustion model was developed by coupling laminar flamelet databases obtained from diffusion flamelets and premixed flamelets. The model employed three control variables, namely, mixture fraction, reaction progress variable and enthalpy. The preferential diffusion effects were included in the laminar flamelet calculations and in the diffusion terms in the transport equations of the control variables. The resulting model is then validated against an experimental diesel-hydrogen dual-fuel combustion engine. The results show that the FGM hybrid combustion model incorporating preferential diffusion effects in the flame chemistry and transport equations yields better predictions with good accuracy for the in-cylinder characteristics. The inclusion of preferential diffusion effects in the flame chemistry and transport equations was found to predict well several characteristics of the diesel-hydrogen dual-fuel combustion process: 1) ignition delay, 2) start and end of combustion, 3) faster flame propagation and quicker burning rate of hydrogen, 4) high temperature combustion due to highly reactive nature of hydrogen radicals, 5) peak values of the heat release rate due to high temperature combustion of the partially premixed pilot fuel spray with entrained hydrogen/air and then background hydrogen-air premixed mixture. The comparison between diesel-hydrogen dual-fuel combustion and diesel only combustion shows early start of combustion, longer ignition delay time, higher flame temperature and NOx emissions for dual-fuel combustion compared to diesel only combustion. • FGM hybrid combustion model for dual-fuel engine combustion modelling. • Preferential diffusion effects on hydrogen blended dual-fuel combustion. • In-cylinder pressure and heat release rate are well predicted. • Auto-ignition delay time and hydrogen radicals are better captured. [ABSTRACT FROM AUTHOR]

This paper presents a novel algorithm, called Visual Fire Power, for measuring the heat release rate of a turbulent flame using video footage taken from two cameras, located at an approximate right angle to each other and at a known distance from the fire. By measuring the time-averaged volume of the fire, Visual Fire Power can measure heat release rate in situations where traditional calorimetry may be impractical (such as experiments outdoors), as well as uniquely providing a method for comparing the heat release rates of different flames in the same experiment, e.g. externally venting flames from different windows of the same compartment. The algorithm was benchmarked against synthetic data and calculated the volume of common solids with approximately 30% uncertainty. The relationship between volume and heat release rate was then calibrated from videos of burners at known heat release rates. These experiments were used to calculate the Orloff-DeRis constant γ , which linearly relates flame volume and heat release rate. The value for γ was found to be 1505 ± 183 kW/m3. The algorithm was demonstrated on recordings of a standard Polish facade fire test. Improving the range of data measured in both fire testing and fire experiments could help to increase our knowledge of fire dynamics and provide better data for researchers and engineers in the future. [ABSTRACT FROM AUTHOR]

The effects of adhesive (layer) on fire performances of structural insulated panel (SIP) have been mostly ignored. This research studied modifications to the epoxy resin adhesive (EA) with expandable graphite (EG), ammonium polyphosphate (APP) and calcium carbonate (CaCO3) to prepare an intumescent flame-retardant epoxy resin adhesive (FREA) which was applied to expanded polystyrene (EPS), a typical core material of SIPs. It was found that the FREA had a char yield of 33% which was 7.6 times of that of EA and a higher viscosity than EA. The limiting oxygen index reached a maximum of 37.7% and UL94 passed the V-0 rating when the EPS was coated with FREA, of which the fire performance was even better than flame-retardant EPS. Additionally, the heat release rate, production rates of CO, CO2 and soot and sample back temperatures were all reduced compared to the EPS coated with EA. Avoiding the sample surface recession in the cone calorimeter, the custom-made spray gun system proves that the FREA can significantly increase the ignition time and lead to self-extinguishment. The degradation products of APP crosslink with CaCO3 to produce phosphates which bond with expanded EG forming the char layer to prevent heat and flame. The use of flame-retardant adhesives can lead to a sufficient fire safety level for the core material without affecting its functions. [ABSTRACT FROM AUTHOR]

Façade fires in tall buildings are currently occurring more than once a month globally that are responsible for many casualties and billions of dollars in losses. In particular, the tragic Grenfell Tower fire in London with more than 70 fatalities raised the profile of façade fire hazard. This work used well-controlled irradiation up to 60 kW/m2 to re-assess the fire hazard of typical flame-retardant aluminum composite panels (ACPs) with a dimension of 10 cm × 10 cm × 0.5 cm. We found that the vertically oriented ACPs with the "non-combustible" A2-grade and "limited-combustible" B-grade cores could still be ignited above 35 kW/m2 and 25 kW/m2, after the front aluminum layer peeled off. The peak heat release rate per unit area of these ACPs could be higher than common materials like timber and PVC. Moreover, compared to the B-core panel, the A2-core panel showed a greater fire hazard in terms of a shorter ignition delay time, a higher possibility of the core peel-off, and a longer flaming duration under current test size and fixing condition. Because the ACP is a complex system, its fire hazard is not simply controlled by the core material. The structural failure of ACP in fire, including peel-off, bending, softening and cracking, may further increase the fire hazard depending on the scale effect, boundary and fixing conditions. This research improves our understanding of the systematic fire behaviors of façade panels and helps rethink the fire risk and test methods of the building façade. [ABSTRACT FROM AUTHOR]

A numerical model of the high-speed train carriage fire is established in this study. The influence of ceilings, sidewalls, luggage racks, seats, and floors on the heat release rate (HRR) of the high-speed train is studied by numerical methods. The results indicate that the heat release rate per unit area (HRRPUA) of ceiling and seat material dramatically influences the peak HRR and the time to peak HRR of train carriage fire. When the peak HRRPUA of interior ceiling material 1 decreases from 326 to 110 kW/m2, the peak HRR of the high-speed train fire decreases from 36.4 to 16.5 MW, with a reduction ratio of 54.7%. When seat materials with low HRRPUA are used, the peak HRR reduction ratio is 44.8%. The HRRPUA of the sidewall, luggage rack, and floor materials has little effect on the peak HRR of the carriage fire. However, the non-combustible luggage rack can delay the time when the HRR reaches its peak. [ABSTRACT FROM AUTHOR]

Cables are the most common combustibles in nuclear power plants (NPPs) and cable fires are the one of main threaten to the safety of NPPs. Fire characteristics and fire hazards for two typical cables used in NPPs were comparatively studied based on cone calorimeter and cable tray fire tests. The heat release rate (HRR) curves show different patterns, two-peaks and three-peaks for NPP and conventional flame retardant cables, respectively. This difference is attributed to the fire barrier, which distinguishes the burning of sheath and insulation. Moreover, the maximum value of HRR for conventional flame retardant cable is much higher than NPP flame-retardant cable, and the difference is 108 kW m−2. The time from first peak to second peak for NPP flame-retardant cable is approximately four times as conventional flame retardant cable. Based on cable tray fire, the burning time after burner off is much longer for conventional flame retardant cable and its total mass loss is 0.52 kg, which are three times and five times as much as NPP flame-retardant cable, respectively, and it has a self-sustaining stage during cable burning. The above indicates that the NPP flame-retardant cable has less sustained damage, fire development rate and overall fire hazard. In addition, spacing has little effect on the burning time of sheath, but the burning of insulation layer is promoted, the time from first peak to second peak decreases with the increase in spacing. However, the influence of spacing is non-monotonous in cable tray fire, and the burning of cables with 10 mm spacing has higher fire hazard with a maximum mass loss rate. [ABSTRACT FROM AUTHOR]

The combined impact of the MFC and EGR methods on the performance of the C.I. engine is investigated experimentally in this study. The work focused on biodiesel fuel under the effect of different EGR rates 10-30% with the optimal value of fuel polarization. At first, the magnetic intensity optimization was done with other engine design parameters by using diesel fuel alone. The study covered a wide range of engine parameters to select the optimal valves. Using the Taguchi approach and orthogonal array L16 to solve the five factors, such as: CR (15,16,17, and 18), IP (175,200,225, and 250 bar), MFC (4000,6000,8000, and 12000 Gauss), load (25,50,75, and 100%), and TI (19, 21, 23, and 27 degree b TDC). The results showed that the diesel engine's optimum parameters were CR=18, IP=200bar, MFC=8000 Gauss, load 100%, and TI=23°b TDC. The results indicated that the coefficient of determination has an excellent level (i.e.), R2 =97.05% Peak fisher valve F=8.37, with normally distributed and significant coefficients in the model, was utilized to test the model capability. The outcome shows that the 10WCO+10% EGR+8000G has higher cylinder pressure and the BTE increased by 12.5% if compared with DF, and lower brake specific fuel consumption. [ABSTRACT FROM AUTHOR]

It is commonly assumed in fire modelling that suppression systems can control the heat release rate of a fire. However, many performance-based assumptions are derived from experimental data for sprinklers, and uncertainty remains for their application to water mist systems. In the UK, residential water mist systems are usually tested to the BS 8458:2015 standard, but the heat release rate in these tests is not quantified and focus is instead placed on thermocouple temperatures. This paper details a series of fire tests to the BS 8458:2015 standard for an electronically controlled water mist system. The paper also includes B-RISK zone modelling of these tests to estimate the suppression performance of the system, comparing model outputs to thermocouple test data. Three traditional suppression assumptions, historically derived from experimental data for sprinklers, have been adopted in the zone modelling to examine whether their application following system activation can be extended to the tested water mist system. The work indicates that applying these suppression assumptions remains reasonable in the context of the performance of the tested water mist system, noting the constraints of the test methods in representing a limited number of fire scenarios. [ABSTRACT FROM AUTHOR]

Probabilistic fire simulation has been gaining interest in performance-based design approach. Very few evaluations on modelling performance can lead to unnecessary simulations which limit the understanding of fire engineering practitioners to select suitable model for a specific fire phenomenon. This study presents comparison of models' capabilities to recreate kitchen fire experiment through probabilistic assessments when there are various possibilities of fire spread can occur within the compartment. Such situation must consider the possible heat release rate curve from previously burning kitchen item, as this will effect on the possibility that other item igniting, and so enhance the intensity of fire. Determination of accumulated heat release rate data is assessed through the use of B-RISK and simplified model. Simulation input employs design fire for single furniture that was characterized through combination of peak growth and exponential decay functions using statistical analysis of fire severity characteristics from collated experimental data. Probabilistic correlation discloses that both models are able to produce results within an acceptable range of fire practice (> 20%), but B-RISK has better representation of possible cumulative heat release rate region than simplified model when more than 58% similarity of fire spread predictions among multiple items is achieved over different boundary ranges. [ABSTRACT FROM AUTHOR]

Estimation of design fires and thermal exposure conditions is an important step in structural fire engineering procedures. Mass timber, as a combustible material, may contribute to the fire intensity, yet there lacks methods to estimate design fires in compartments with exposed timber. This paper summarizes available experimental data on the contribution of exposed timber to heat release rate, describes a simple analytical method to evaluate this contribution, and discusses the effects on time–temperature curves and required firefighting resources based on a case study. Results show that the total heat release rate in compartments increases with the surface of exposed timber. This total heat release rate can be conservatively estimated using empirical relationships for ventilation-controlled burning rate and charring depth. In estimating gas temperature–time curves, both external flaming and extended fire duration combustion models can be applied to obtain an envelope of fire severity inside the compartment and for external spread. The proposed assessment approach provides a method to evaluate realistic design fires in timber buildings and to estimate the water supply required to put out these fires. Accurate modeling of the contribution of timber to fire severity is important for the design of mass timber construction as well as for the safety of firefighters. [ABSTRACT FROM AUTHOR]

A new Outdoor Gas Emission Sampling (OGES) system was developed to serve as a low-cost alternative to expensive industrial gas sampling equipment. This research showed its effectiveness in sampling a smoke plume from multiple points simultaneously, obtaining gas concentration curves for common products of combustion such as CO2 and CO in meso-scale experiments. The optimal height for combustion product sampling was determined based on a variety of factors, most notably CO/CO2 ratio, which showed to be most consistent when located in the intermittent and plume regime of the McCaffrey plume. Large-scale field tests at U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) in collaboration with the Environmental Protection Agency (EPA) demonstrated the potential of using OGES to evaluate the completeness of combustion for various fuels in a variety of settings. Oxygen Consumption (OC) and Carbon Dioxide Generation (CDG) methods in combination with plume theory results show the potential of using point sampling within a smoke plume to estimate HRR for fires that exceed the capabilities of conventional hood-based calorimeters. [ABSTRACT FROM AUTHOR]

• BR and SBR have two HRR peaks at heat fluxes lower than 20 kWm−2. • At the ignition time, the crosslink degree of surface layer reaches 84.23–100 %. • The model considering the crosslink reaction can predict the two-peak HRR curve. • At low heat flux the crosslink reaction has a long residence time before ignition. • The first HRR peak results from the crosslink reaction. Understanding the combustion behavior of rubbers is crucial for predicting their fire hazards. The cone calorimeter experimental results in this study confirm that the combustion behavior of raw rubbers depends on the rubber type and the heat flux. Natural rubber and ethylene-propylene-diene monomer rubber exhibit heat release rate (HRR) curves with only one peak at the end of the burning stage under all tested heat fluxes. At higher heat fluxes, the HRR curves of polybutadiene rubber (BR) and styrene butadiene rubber (SBR) exhibit a single peak; at heat fluxes lower than 20 kWm−2, two HRR peaks were observed. The proposed mechanism model with the crosslink reaction as the key factor can explain the emergence of two-peak HRR curve and has been proved through experiments and simulations. For BR and SBR at 15 kWm−2, the specimens exhibit two upper layers at ignition time. The surface pyrolysis layer seems to be covered by black film or char, with the crosslink degree as high as 84.23–100 %. The second crosslink reaction layer exhibits a higher decomposition temperature T d, 5 % than the original rubber. Based on reaction kinetics and thermodynamics data derived from TG/DSC experiments, the novel pyrolysis model taking crosslink reaction and thermal decomposition of crosslinked intermediate into account well predicts the HRR curves obtained at varied heat fluxes. The conversion of raw rubber to the crosslinked intermediate plays an important role in the reduction of HRR immediately after ignition, resulting in the first HRR peak. [ABSTRACT FROM AUTHOR]

In the backdrop of the modernization of intelligent mining in the China, the stability of mining cables directly affects the operational stability of the entire underground electrical system in the mine, and studying the fire risk of mining cables is crucial. A cone calorimeter was used to conduct a comprehensive analysis of the ignition time, mass loss rate, heat release rate, smoke generation rate, total smoke production, and the production rates of CO2 and CO for two types of mining cables (MYP and MYJV). Five indicators (FPI, FGI, THRI6min, TSPI6min, and ToxPI6min) were used to investigate their fire risks. The results showed that the ignition time of MYP mining cables was longer than that of MYJV mining cables; the peak mass loss rate of MYP mining cables was lower than that of MYJV mining cables, with MYP cables having a larger latent heat of vaporization and more prominent thermal lag; MYJV mining cables release more heat during combustion; the smoke generation rate and total smoke production of MYP mining cables were lower than those of MYJV mining cables; the production rates of CO2 and CO for MYJV mining cables were higher than for MYP mining cables; thus, MYJV mining cables pose higher fire risk compared to MYP mining cables. This study better evaluates the fire hazards of two commonly used mining cables and provides a theoretical basis for the prevention and control of cable fires in mines. [ABSTRACT FROM AUTHOR]

The combustion and ignition characteristics of three fuels with different reactivities have been investigated by a reduced chemical kinetic model. In the present work, the chemical kinetics of conventional single fuel and binary fuel, relevant to gas-turbine engines, are extended and attempted to explore in the tri-fuel (TF) context, with the help of TF blends of LPG + CH 4 +H 2 at the pressure and temperature range of 1–20 atm and 900–2000 K, respectively. The blending of hydrogen with hydrocarbon fuels improves flame propagation, reduces emissions, and increases the combustion performance of the engine. A detailed study is conducted to explore the characteristics of TF mixture over a wide range of operating conditions by considering eight different test mixtures (M1-M8). The test mixtures (M2 to M4) contain higher hydrogen content and thus hydrogen kinetics will tend to dominate, while test mixtures (M6 to M8) contain a higher concentration of hydrocarbons, thus the methyl radical chemistry plays a prominent role in the oxidation process. Such contrasting trends were further explored by extensive chemical kinetic modeling with the help of the reduced USC Mech_50 species model from our previous work [1] to analyze the ignition delay time, laminar flame speed, flame temperature, and heat release rate characteristics. In addition, the reaction pathway analysis through sensitivity analysis of OH and CO radical, and flow rate sensitivity analysis has also been conducted to highlight the essential chemical reactions which play a crucial role in auto-ignition, combustion, and emissions characteristics of TF blends. • Tri-fuel (TF) ignition characteristics using a reduced skeletal mechanism. • TF composition affecting flame propagation speed and burning fluxes. • Heat release rate enhancement through H, O and OH radicals. • Reaction pathway and sensitivity analysis for important species and reactions. [ABSTRACT FROM AUTHOR]

This work presents experimental results of combustion characteristics of low volatile Indian coal. Coal of different average relative density (ARD) varying from 1.35 to 2.0 was generated by density fractionation of the coal. Coal samples were characterized by proximate analysis, Fourier-transform infrared spectroscopy (FTIR), ultimate analysis, and gross calorific value (GCV). Combustion experiments were conducted to identify the effects of ARD and functional groups on combustion characteristics. It was observed that with the rise in ARD of coal from 1.45 to 2.0, the ignition temperature increased from 357°C to 417°C. Highest coal combustion rate was observed for 1.525 ARD coal, due to the presence of all types of hydrocarbons, alcoholic, aldehyde, and trisubstituted alkene (except primary amines) as seen from FTIR analysis. Analyses of coal combustion rate and GCV indicate that 1.45 ARD coal has the highest GCV, heat release rate, and lowest ash generation rate, properties that are best suitable for thermal utilities. [ABSTRACT FROM AUTHOR]

Thermal safety is important for the process of storage and utilization of lithium-ion battery. Once battery thermal runaway (TR) happens, accidents are difficult to avoid. As a cooling medium for battery thermal management, phase change material (PCM) can effectively maintain the temperature under normal operations. However, the flammability of PCM makes it doubtful to work safely under extreme conditions like TR. Herein, several sets of TR experiments have been conducted on 18650 batteries covered without and with different PCMs. Paraffin PCM (PPCM) and composite PCM (CPCM) are considered to explore their effects on TR. Results demonstrate that PPCM delays the onset of TR by 277 s and lowers the battery temperature utilizing its heat absorption while CPCM has little effect. However, flammable PPCM increases the heat release significantly which brings great fire risk. Based on the foregoing, a flame-retarded PPCM mixed with hydroxide flame-retardant proved to relieve the adverse effects of PPCM as well as maintain the performance for inhibiting TR. Results show that the addition of flame retardants reduces the peak heat release rate from 29 kW to 15.5 kW, which gives guidance in the process safety assurance and fire protection design in a real engineering application of battery thermal management. [ABSTRACT FROM AUTHOR]