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Cabin fires and emergency evacuation of personnel are hot topics in aviation safety. To obtain the characteristics of cabin fires and personnel evacuation, a study is conducted on the Boeing 737, and the results show that after the fire occurs, smoke first spreads towards the top and then rapidly spreads towards both ends of the cabin. The propagation speed of smoke is greater than that of flame, as the spread of flame is limited by the oxygen concentration in the cabin. Although the partition between business class and economy class has a significant obstructive effect on the spread of smoke, the effectiveness of the partition in blocking heat and high temperature transfer is limited. When a fire occurs in the cabin and emergency evacuation is required, it takes 80.5 s to evacuate all personnel when all eight cabin doors are open. But when emergency hatches fail to open, it is not until 164.8 s that all personnel in the cabin are evacuated, mainly because people in the economy class can only be evacuated through the front and rear cabin doors, which reduces the evacuation rate. The research on cabin fire and emergency evacuation of personnel can provide reference for fire monitoring and firefighting rescue.

To discuss the ignition energy, explosion flame propagation, and particle movement process of coal dust in vertical glass tube, experimental analysis and numerical simulation methods are used to carry out research. The experimental research results show that the optimal ignition delay time is 1 s, under this condition, the dust cloud near the ignition electrode has the highest turbulence, making it easier to ignite. When the dust cloud mass concentration is 2500 g/m3, the ignition energy is the smallest, resulting in the highest risk of explosion. The simulation results show that the propagation speed of flame is 4 m/s, due to the small amount of suspended dust used, the intensity of the explosion is not significant. The further away from the explosion source, the more energy is lost, the lower the temperature of the flame. Within 30∼50 ms after the ignition, the temperature near the explosion source rapidly increases, from 900 K to 1300 K. During the period of 0.2–0.5 s after dust injection, most particles move upwards along the tube. At 1 s after the dust injection, most particles move downwards and gather near the ignition electrode, forming a suspended dust cloud that is easily ignited, which is consistent with the optimal ignition delay time of 1 s obtained from the experiment.

The propulsion research lab at Utah State University has developed a minimally-intrusive optical sensing system for high-temperature/high-velocity gas-generator exhaust plumes. For this application glass fiber-optic cables, acting as radiation conduits, are inserted through the combustion chamber or nozzle wall and look directly into the flow core. The cable transmits data from the flame zone to externally-mounted spectrometers. In order to capture the full-optical spectrum, a blended dual-spectrum system was employed, with one spectrometer system tuned for best-response across the visible-light and near-infrared spectrum, and one spectrometer tuned for best-response in the near- and mid-infrared spectrum. The dual-band sensors are radiometrically-calibrated and the sensed-spectra are spliced together using an optimal Wiener filtering algorithm to perform the deconvolution. The merged spectrum is subsequently curve-fit to Planck's black-body radiation law, and flame temperature is calculated from associated curve maxima (Wien's law). The presented fiber-optic sensing systems performs a function that is analogous to Raman spectroscopy. The system non-contact, high-temperature measurement, and does not interfere with the heat transfer processes. In this report data collected from a lab-scale (200 N) hybrid rocket system are analyzed using the described method. Optically-sensed flame-temperatures are correlated to analytical predictions, and shown to generally agree within a few degrees. Additionally, local maxima in the optical spectra are shown to correspond to emission frequencies of atomic and molecular oxygen, water vapor, and molecular nitrogen; all species known to exist in the hybrid combustion plume. Presented data demonstrate that selected fiber-optics can survive temperature greater than 3000 ℃, for durations of up to 25 seconds.

This work explains the optimized synthesis process and preparation of a novel environmental friend and commercial biodiesel from Salicornia persica Akhani (SpA) as a low-water, drought-resistant, and saltwater tolerant plant and presents the comparative results on thermal and emission characteristics due to the application of this biodiesel in a combustion system. The effects of extraction method, kind of extraction solvent (polar and non-polar solvent), extraction time (10–25 min) and ratio of Salicornia grounded seeds to solvent (0.11–0.33 g/ml) on the yield of the extraction process were studied. The ultrasonic probe method with hexane solvent at 25 min of extraction time and 0.33 g/ml solute to solvent ratio gave the maximum oil yield of 33 wt% during the experiment. Conversion of Salicornia seeds oil into biodiesel was done with methanol in the presence of the Zn0.4Ni0.6Fe2O4@SO3H magnetic nanocomposites during transesterification reaction. Also, Fourier Transform Infrared technique (FT-IR) was done to show the oil conversion into biodiesel. Having a high amount of unsaturated fatty acids (USFA) and a low amount of saturated fatty acids (SFA) resulting from Gas Chromatography analysis (GC) and high oxidative stability of Salicornia seeds oil leads to the Salicornia persica Akhani biodiesel having the lowest dynamic viscosity (3.32 mPa.s at 40 °C) compared to other conventional biodiesels including palm, sunflower and soybean. Low viscosity has an essential role in the enhancement of fuel atomization, mixing, combustion and CO emission such that compared with B20 palm oil biodiesel fuel, the use of a B20 blend of Salicornia persica Akhani in an oil burner increases the maximum flame temperature by 3.7 % and decreases the CO emission by 46.5 %.

The determination of the characteristics and main combustion properties of fuels is necessary for post-implementation in different applications. Among the most important combustion properties of a fuel are the combustion products, flame temperature and laminar burning velocity. Therefore, this paper describes the step-by-step development and coding of a MATLAB application that can determine 12 combustion products, flame temperature and laminar burning velocity in order to understand the logic of calculus procedure, so any user would be able to make improvements of new functionalities (add more fuels, add more combustion products, etc.). The numerical procedure and methods (Gaussian elimination, Taylor Series and Newton–Raphson) parallel with their implementation as code lines for the development of the application are carried out using flow charts. In addition, simulations in Ansys Chemkin were performed and included in the application as part of the results comparison. It was found that: (1) The MATLAB Application codification and development were successfully explained in detail, (2) the functions and execution sequence are described by using flow charts and code extract, (3) the application is available to everyone for modifications, (4) the application can only be used for hydrocarbons fuels, (5) the application execution time registered was less than 8 s.

We conducted a numerical study of the effects of a vortex generator (VG) on the combustion characteristics and physical fluid flow of LPG on a porous bluff-body slot burner (PBSB) model, validating the numerical and experimental results of the temperature distribution and mixture flow velocity. The VG position (fuel (F) and air (A) slots), direction (clockwise, CW, and counterclockwise, CCW), aspect ratio (AR), and distance (S) were investigated parametrically in our porous vortex generator slot burner (PVGSB) model. According to our results, the VGSB model with a VG angle of 60°, CW direction, aspect ratio of 0.4, and VG distance of 0 mm enhanced the flame temperature by 24.4% due to a greater vortex influence. Moreover, applying a reverse triangular bluff body to the VGSB model had a stronger effect on the vortices and swirl flow of the mixture compared to the cylindrical bluff body, achieving 34.9% higher combustion temperatures compared to the referenced PBSB model. This numerical study of using LPG combustion on a slot burner with VGs and a reverse triangular bluff body, which we refer to as the VGSB model, could be applied to enhancing physical air–fuel flow and the flame temperature as characteristics of combustion.

Formic acid is a promising candidate fuel that can be produced by reacting renewable hydrogen with carbon dioxide. However, the burning safety characteristics of formic acid–air mixtures have not been fully studied. This paper presents an extensive theoretical study of the adiabatic explosion pressure of formic acid–air premixed laminar flames at various initial conditions (composition of formic acid: 17–38% volume; initial pressure: 0.1–1.5 bar; initial temperature: 333–500 K), using the GASEQ software package. GASEQ software calculates chemical equilibria based on ideal gas behavior and is based on the hypothesis of adiabatic expansion inside a closed containment that allows ideal expansion. The influence of the initial conditions (pressure, temperature, and concentration) of formic acid–air mixtures on the adiabatic explosion pressures, maximum flame temperature, and peak concentrations of the main reaction intermediates is investigated and discussed. It is found that the adiabatic peak explosion pressure (calculated equilibrium pressure) of the studied concentrations decreases with increasing initial temperature and increases linearly with increasing initial pressure.

The microstructures play a crucial role in the combustion of aluminum/polytetrafluoroethylene (Al/PTFE) materials. Mechanically activated Al/PTFE typically demonstrates higher reactivity but a lower combustion rate compared to physically mixed Al/PTFE. Recently, the combustion performance of fuel-rich Al/PTFE has been well explained by the microexplosion mechanism. In this study, the combustion characteristics of stoichiometric Al/PTFE (26.5:73.5 wt%) materials with varying microstructures were investigated to further the understanding of their combustion mechanism and offer insights for their potential applications in metal cutting. The Al/PTFE materials with different microstructures were prepared using sonication and ball milling methods. The results of scanning electron microscope (SEM) analysis suggest that the sonicated Al/PTFE (s-Al/PTFE) containing spherical Al particles displayed a loosely dispersed structure, while the milled Al/PTFE (m-Al/PTFE) exhibited a densely layered structure with flake-like Al particles coated by the PTFE matrix. The milled Al/PTFE was found to be mechanically activated. Combustion in quartz tubes was recorded using a high-speed camera and a video. Combustion of s-Al/PTFE demonstrated a high-temperature flame (∼2346 K) and obvious microexplosions featuring hot particles ejection, while combustion of m-Al/PTFE showed a weak flame (∼2037 K) and slow-burning, featuring dense carbon smoke. Increasing the powder density was observed to slightly decrease (∼100 K) flame temperature. Microstructure and phase analysis of combustion products were systematically conducted to elucidate the combustion behaviors. The results suggest that the residue of s-Al/PTFE contained high AlF _3 and low carbon content, whereas the residue of m-Al/PTFE exhibited the opposite condition. The results of the combustion tests suggest that microexplosions promoted the oxidation of hot Al particles and carbon products, consequently leading to a fast reaction, high flame temperature, and enhanced heat transfer capability.

Large-bore marine diesel engines have the characteristics of poor ignition performance and insufficient combustion in the cylinder. This work revealed the combustion and emission performance of large-bore marine diesel engines based on endoscopic visualization technology. The flame temperature and soot distribution were analyzed in radial and axial directions. Results show that the large-bore diesel engine has a poor combustion effect because of the large fuel injection quantity and insufficient fuel-air mixing effect in the cylinder. The temperature in the cylinder rises twice in the late stage of combustion. The average temperature rises by 3.8%, caused by the secondary ignition of part of the unburned diesel. In addition, the large-bore engine produces a large amount of soot due to an insufficient mixing effect. It can be observed from the radial flame visualization images that the propagation speed of the flame is slow. The time required for the flame to propagate to the wall at 50% load is reduced by 31% compared with 25% load. The downward movement of the piston causes the flame tumble flow in the cylinder, resulting in an apparent asymmetric structure of the flame development.

The temperature of the flame of copper concentrates was determined through spectral measurements by using an optical and infrared spectrometer, where the experimental data were adequately processed by the two-colour pyrometer method. Experiments were carried out in a drop-tube, and the furnace temperature was 773 K ensuring the ignition of concentrates. This technique allowed an in-situ evaluation to be made of the effect of the oxygen content in the feed gas and the sulphur in the concentrate. Two intense peaks at 750 nm wavelength from spectral measurements may be explained by the oxidation of labile sulphur in concentrates. The flame temperature was between 1600 and 2100 K and this increased with both oxygen concentration and S/Cu ratio. The direct study of emission spectra through unique measurement probes can help to have a more profound vision of what is happening with the concentrated particles subjected to flash combustion conditions. This work has special interests in the pyrometallurgical industry, presenting a critical lack of non-invasive techniques for monitoring and controlling the process.

This research aimed to the characteristics and influence factor of methane and coal dust gas/solid two-phase mixture explosions by experiment. Through comparative analysis of flame propagation characteristics, pressure, flame temperature and products, the characteristics of gas/solid explosions and its influence factor were analyzed. And the influence mechanism was also revealed. Results indicate that the coal dust parameter and methane concentration were the important influence factor on mixture explosions. Explosion intensity could be indirectly affected by influencing the flame propagation. Under the determined coal dust parameter, the explosion parameter showed a change trend of increase firstly and then decrease as the methane concentration increased. And it was the greatest at 6% methane concentration. However, the concentration of coal dust corresponding to the maximum pressure was variable and was decreased successively as the methane concentration increased. The corresponding dust concentrations were 500 g/m3 and 200 g/m3 under 2% and 10% methane concentrations, respectively. Meanwhile, the pressure all presented an increasing trend with the reduction of coal dust diameter under five coal dust concentrations, and the explosion intensity was the greatest at 300 g/m3 coal dust concentration. For 2% methane concentration, the explosion would not occur as the dust concentration was less than 400 g/m3. And the same phenomena also appeared as the methane concentration exceeded 10%. The explosion parameter presented the same change trend with the changes of methane concentration and coal dust parameters. Besides, the thermal stability and decomposition oxidation characteristics of burned coal dust were evidently changed compared with unburned coal dust. The weight loss rate and oxidation reaction rate were decreased, and the corresponding temperature was increased. It indicates that coal dust participated in gas/dust two-phase explosion reactions, and the pyrolysis reaction of volatile matter led to an obvious reduction in the weight loss and oxidation reaction rate. And the precipitation of volatile matter also resulted in an obvious pore structure on its surface. The physical parameters and internal components of coal dust were important factors affecting the reaction rates of gas/dust mixture explosions.

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.

The characterization of a specific fuel has always been an important point for developing and designing new components or systems with the maximum efficient possible. Studying the laminar burning velocity can lay a necessary prerequisite for the accurate poststudy of the turbulent range and to understand how the combustion process takes place. The study of the combustion products from a specific reaction is a requisite for any system in order to understand the elements that are taken in the process and if it is possible to improve it. In this study, a new open code methodology was developed for the determination of combustion products, flame temperature and laminar burning velocity using numerical methods (Newton–Raphson, Taylor series and Gaussian elimination) in an application codified in MATLAB. The MATLAB application was applied for the study of Saudi LPG setting parameters such as initial temperature, pressure and equivalence ratio that are meaningful because they have a great effect on the results. In addition, simulation in Ansys Chemkin using San Diego and RedSD mechanisms was carried out. The results from the MATLAB application were compared with other experimental research and Ansys Chemkin simulation. These are presented in different plots and it is shown that: (1) For the laminar burning velocity results, the numerical method agrees with the experimental results for ratios (0.6–1.2) by other authors and the simulation in Ansys Chemkin. (2) For the highest studied equivalence ratios (1.3–1.7) the laminar burning velocity results between all the resources have more difference. (3) The combustion products calculated by the MATLAB application agree with those simulated in Ansys Chemkin except N and NO. (4) The MATLAB application gives a maximum value of 40.35 cm/s, that is greater than 35 ± 0.91, the one determined by Bader A. Alfarraj. (5) The flame temperature calculated by the MATLAB application overestimates that simulated in Ansys Chemkin but has the same behavior for all the calculated ratios. (6) The MATLAB application has also been developed for the study and analysis of other fuels.

Closed coal bunkers emerged as a novel form of coal storage for coal-fired power stations. Nevertheless, heat builds continually in the storage process because of the constant oxidation of coal and combined with the impact of a confined coal bunker environment, it is difficult for heat to dissipate, resulting in frequent coal bunker fires. Consequently, research on coal pile combustion characteristics is crucial to the design of coal bunker safety. The experimental platform was set up in this study to conduct combustion tests of various specifications, and the burning rate, flame height, flame temperature, and heat radiation flux were analyzed to identify the critical parameters impacting coal bunker safety. First, the maximum burning rate of coal heaps during steady burning was calculated, improving coal pile combustion theory and providing guidance for coal bunker design. Second, the maximum flame height was determined, which can provide an important design guide for coal bunker height designs. In addition, it was discovered that high temperatures in flames, smoke, and smoldering coal might cause coal bunker buildings to collapse, so future designs should strengthen coal bunker fire resistance and keep the coal pile away from the load-bearing structures to prevent collapse from excessive temperatures. Moreover, the diameter of coal piles has an influence on the heat flow. For this reason, a coal bunker’s design must consider the coal pile’s fire separation distance from the coal bunker and avoid large coal piles. Consequently, the study gives recommendations and support for planning coal bunker safety and enriches experimental data for coal pile fires.

In this paper, the combustion properties of ethylene carbonate/propylene carbonate/ethyl methyl carbonate (EC/PC/EMC) with LiPF6 or LiPF4 were studied by cone calorimeter under various environmental pressures in Hefei (100.09 kPa), Lijiang (76.11 kPa) and Lhasa (65.23 kPa), respectively. The impact of lithium salts and pressure on the significant fire parameters of electrolyte such as flame temperature, mass loss rate (MLR) and heat release rate (HRR) were analyzed to evaluate the degree of thermal hazard. The experimental results showed that with the decrease of ambient pressure, the peak HRR (pHRR) and total heat release (THR) declined, and the combustion duration increased significantly. In the steady combustion stage of electrolyte pool fire, the mean value of MLR had an exponential relationship with the external pressure. The error of HRR obtained by oxygen consumption (OC) calorimetry and stoichiometric thermochemistry (TC) theory was about 15%.

This study deals with different machine learning algorithms modeling of small-scale burner to predict the temperature from the top and bottom of the flame from combustion of ethanol-diesel fuel blends. The data used for training and testing of the proposed algorithms was acquired by combusting ethanol-diesel fuel blends at different fuel mixing proportions, inner diameters of quartz tubes, flow rates of air and volume flow rates of blend in small-scale burner. Three models for machine learning algorithm based on back propagation (BP), generalized regression neural network (GRNN) and support vector machine (SVM) for small-scale burner were established employing the experimental data for training and testing. The feasibility of these algorithms in predicting the flame temperature of ethanol-diesel combustion in small scale were contrasted by performance correlation coefficient (R) and mean absolute percentage error (MAPE). The results showed that all three algorithms could well identify the complicated nonlinear relationship between the flame temperature and related variables. In addition, for the top temperature, the R value of the SVM model was the largest, which was 0.98513, and the MAPE value was the smallest, which was 1.60%. And, for the bottom temperature, the R value of the SVM model was the largest, which was 0.98135, and the MAPE value was the smallest, which was 1.84%, similarly. Therefore, the SVM model could predict the flame temperature of small-scale burner well, and its performance was the best among the three machine learning algorithms.

Automobiles with internal combustion engine using diesel fuel have large harmful emissions of nitrogen oxides and soot, which affect the health of the population and especially children and carbon dioxide, which is dangerous for the planet as a whole. Biodiesel is used in Europe as an additive to diesel fuel to reduce soot emissions (including carcinogens), as well as to improve the balance of carbon dioxide on the planet. Using the biodiesel in internal combustion engines tends to show higher nitrogen oxides emissions compared to diesel. In this paper, the impact of flame temperature, ignition delay and density on NOx formation of biodiesel and its component for both stationary engine and automotive engine were analysed. Emissions of nitrogen oxides increase with increasing load. In no-load modes, biodiesel shows lower emissions of nitrogen oxides than diesel.

Using high charge dilution low temperature combustion (LTC) strategies in a diesel engine offers low emissions of nitrogen oxides (NOx). These strategies are limited to part-load conditions and involve high levels of charge dilution, typically achieved through the use of recirculated exhaust gases (EGR). The slow response of the gas handling system, compared to load demand and fuelling, can lead to conditions where dilution levels are higher or lower than expected, impacting emissions and combustion stability. This article reports on the sensitivity of high-dilution LTC to variations in EGR rate and fuel injection timing. Impacts on engine efficiency, combustion stability and emissions are assessed in a single-cylinder engine and compared to in-cylinder flame temperatures measured using a borescope-based two-colour pyrometer. The work focuses on low-load conditions (300 kPa gross indicated mean effective pressure) and includes an EGR sweep from conventional diesel mode to high-dilution LTC, and sensitivity studies investigating the effects of variations in charge dilution and fuel injection timing at the high-dilution LTC condition. Key findings from the study include that the peak flame temperature decreased from ~2580 K in conventional diesel combustion with no EGR to 1800 K in LTC with low-NOx, low-soot operation and an EGR rate of 57%. Increasing the EGR to 64% reduced flame temperatures to 1400 K but increased total hydrocarbon (THC) and carbon monoxide (CO) emissions by 30–50% and increased fuel consumption by 5–7%. Charge dilution was found to have a stronger effect on the combustion process than the diesel injection timing under these LTC conditions. Advancing fuel injection timings at increasing dilution kept combustion instability below 2.5%. Peak in-cylinder temperatures were maintained in the 2000–2100 K range, while THC and CO emissions were controlled by delaying the onset of bulk quenching. Very early injection (earlier than 24 °CA before top-dead-centre) resulted in spray impingement on the piston crown, resulting in degraded efficiency and higher emissions. The results of this study demonstrate the potential of fuel injection timing modification to accommodate variations in charge dilution rates while maintaining low NOx and PM emissions in a diesel engine using low-temperature combustion strategies at part loads.

To reduce exhaust NOx and smoke, it is important to measure flame temperature and soot amount in combustion chamber. In diesel combustion it is effective to use the two-color method for the measurement of the flame temperature and KL factor, which is related with soot concentration. The diesel flame was directly and continuously observed from the combustion chamber at running engine condition by using a bore scope and a high-speed video camera. The experimental single cylinder engine has 2.0-liter displacement and has the ability with up to five times of the boost pressure than the naturally aspirated engine by external super-charger. The devices of High Boost, Wide Range and High EGR rate at keeping a relatively high excess air ratio were installed in this research engine in order to reduce exhaust NOx emission without smoke deterioration from diesel engines. The video camera nac GX-1 was used in this study. From observed data under the changing EGR rates, the flame temperature and KL factor were obtained by the software of two-color method analysis. The diesel combustion processes are understood well by analyzing high-speed movies of the diesel flame motion and its temperature. The NOx and smoke are mutually related to maximum flame temperature and also it is possible to reduce simultaneously both NOx and soot emissions by high EGR rate in a single cylinder diesel engine.

Research was conducted on fuels with additives that selectively affect the rate of kinetic (dQk/dα) and diffusion (dQd/dα) combustion in the diesel engine cylinder. In addition to the base fuel (DFB), DFKA fuel with an additive reducing dQk/dα, DFDA fuel with an additive increasing dQd/dα, and DFS fuel with both additives were tested. The main purpose of such dQ/dα course control in the engine cylinder was to simultaneously reduce the emissions of nitrogen oxides (NOx) and particulate matter (PM), and to increase the efficiency of the combustion process. Similar to the course of the dQ/dα, the course of the combustion temperature (Tc(α)) affects the NOx produced and the number of afterburned solid particles; the influence of the fuel additives on the functional curves was analysed. In addition to analysis of the temperature Tc(α) calculated from the indicator diagrams, Tc(α) analysis was conducted using the two-colour method, which allows the analysis of the isotherm distributions locally and temporarily. The two-colour method required prior endoscopic visualisation of the fast-changing processes inside the engine cylinder. Parameters defined by pressure, temperature, heat release rate, and visualisation and thermovision in the engine cylinder (as a function of the crank angle) allowed for an in-depth cause and effect analysis. It was determined why combustion of DFS fuel with both additives produced a synergy resulting in the simultaneous reduction in NOx and PM emissions in the exhaust gas and an increase in combustion efficiency. This publication relates to the field of Mechanical Engineering.

The exhaust gas temperature of SOFC is as high as 600–1000 °C and contains combustible components that can be reused. In this paper, an experimental system was set up to study the combustion characteristics of SOFC simulated exhaust gas in a porous medium burner, the combustion of SOFC exhaust gas under different equivalence ratio, the effects of hydrogen concentration and water vapor fraction in the anode exhaust gas and the stable combustion limits of the burners had been analyzed. Results showed that: equivalence ratio and adiabatic flame temperature had a significant effect on the combustion, when the adiabatic flame temperature of mixed gas below 440 °C, or the water vapor content in the anode gas was greater than 85%, the flame couldn’t be stably burned; On the condition of the fuel utilization rate of 60% and the equivalence ratio of 0.40, the burner could burn stably with the inlet airflow velocity from 0.16 to 0.24m/s; The combustion stability limit of the exhaust gas burner varied with the utilization ratio of the stack, with increasing of fuel utilization ratio, the equivalence ratio of lifting and flashback limit was changing, and the adiabatic flame temperature of stable combustion limit had been studied.

In ancient villages, the spread of uninterrupted fires caused great damage to clustered wooden houses. Thus, the spread of fire among wooden houses should be systematically studied to explore its characteristics. Statistical analysis is a feasible way to study the characteristics and underlying mechanisms of fire in full-scale wooden houses. In this study, 4 full-scale wooden buildings were built in an ethnic village in Guizhou Province, and the fire spread test was conducted by igniting a 0.63-MW power wood crib. To investigate the fire spread, the visual characteristics were observed, and the temperatures and heat radiation at special locations were monitored with thermocouples and radiation flowmeters, respectively. The effect of relative slope, heat radiation, and wind direction on fire spread characteristics was established by mathematical statistics, and the measured temperatures were used to verify the statistics’ regularity. The results showed that in wooden houses, fire spread was mainly influenced by the slope, the distance between houses, and wind direction. When the inner wall of a wooden house is protected by a fireproof coating, the thermal radiation spread and fire spread are both slower. The slope and distance had the same influence weight (0.41) on fire spread; however, since they affect the process in different ways, they should be analyzed separately for fire risk evaluation. The findings of this study provide a theoretical foundation for understanding the fire spread process in wooden buildings.

Boron and its alloys have been explored a lot and it is expected that they can replace pure aluminum powder in the energetic formulation of active materials. MgB2 compounds were prepared and characterized by a combination of mechanical alloying and heat treatment. The ignition and combustion of boron–magnesium alloys were studied with the ignition wire method and laser ignition infrared temperature measurement. The results show that MgB2 has good ignition characteristics with maximum ignition temperatures obtained by the two various methods of 1292 K and 1293 K, respectively. Compared with boron, the ignition temperature of MgB2 is greatly reduced after alloying. The ignition reaction of MgB2 mainly occurs on the surface and the ignition process has two stages. In the initial stage of ignition, the large flame morphology and combustion state are close to the combustion with gaseous Mg, whereas the subsequent combustion process is close to the combustion process of B. Compared with boron, the ignition temperature of MgB2 is greatly reduced which suggests that MgB2 may be used in gunpowder, propellant, explosives, and pyrotechnics due to its improved ignition performance.

The article presents the results of experimental research of efficiency of fuel oil combustion in power boilers at TPPs with different layout of burners at different steam loads. Given the values of efficiency of boilers and of emissions of nitrogen oxides when burning fuel oil. The efficiency of using bunk steel counter arrangement of burners.

The article presents the results of investigating the relation between flame chemiionization and the flame temperature and pressure in a variable- volume combustion chamber. Functional dependences of flame temperature and maximum pressure on the electron current caused by flame chemiionization, fundamental characteristics of flame propagation and combustion efficiency are presented. Comparison of the temperature calculated by the proposed method with experimental data shows that with the excess air factor of 0.8 to 1.15, the precision is more than 85%. Comparison of the maximum pressure obtained experimentally and calculated by the refined Vibe model, using the proposed formulas, showed good agreement. The results of the work can be used to predict and monitor maximum flame temperature and pressure in the combustion chamber of an internal combustion engine and other power plants using an ionization probe.

Recent studies have shown that the energy release capacity of Polytetrafluoroethylene (PTFE)/Al with Si, and CuO, respectively, is higher than that of PTFE/Al. PTFE/Al/Si/CuO reactive materials with four proportions of PTFE/Si were designed by the molding–sintering process to study the influence of different PTFE/Si mass ratios on energy release. A drop hammer was selected for igniting the specimens, and the high-speed camera and spectrometer systems were used to record the energy release process and the flame spectrum, respectively. The ignition height of the reactive material was obtained by fitting the relationship between the flame duration and the drop height. It was found that the ignition height of PTFE/Al/Si/CuO containing 20% PTFE/Si is 48.27 cm, which is the lowest compared to the ignition height of other Si/PTFE ratios of PTFE/Al/Si/CuO; the flame temperature was calculated from the flame spectrum. It was found that flame temperature changes little for the same reactive material at different drop heights. Compared with the flame temperature of PTFE/Al/Si/CuO with four mass ratios, it was found that the flame temperature of PTFE/Al/Si/CuO with 20% PTFE/Si is the highest, which is 2589 K. The results show that PTFE/Al/Si/CuO containing 20% PTFE/Si is easier to be ignited and has a stronger temperature destruction effect.

The length and pattern of air–fuel mixing plays a significant role in the uniformity, flame temperature, and emission characteristics, which can lead to a superior product quality in a non-oxidizing direct fired burner for a cold-rolled steel plate furnace. In this study, a diffusion-flame-type burner and partially-premixed-type burner were experimentally investigated to understand their effects on flame shape, flame temperature, and exhaust gas characteristics. With this aim, fuel nozzle size, nozzle hole number, fuel injection angle, and mixing distance of fuel and air were varied during the experiments. Computational fluid dynamics simulations were also performed to investigate the air–fuel mixing state for a nozzle-mixed burner and a partially-premixed burner. The results show that the flame temperature of the partially-premixed burner increases by up to 26 °C on average compared to that of the nozzle-mixed burner. It is also shown that the mixing distance plays an important role in the flame temperature of the partially-premixed burner. In addition, the residual oxygen concentration and volume ratio of CO/CO2 in the flue gas of the partially-premixed burner exhibit lower concentrations compared to those of the diffusion flame burner.

This study aimed to analyze the heat release rate from the combustion process of bioethanol from sago waste to determine the viability and feasibility of low-concentration bioethanol as an alternative fuel. The heat release rate, exhaust gas, and flame temperature were measured using a cone calorimeter, and bioethanol combustion was conducted using the pilot ignition method, with an ethanol quality range of 60–70%. The analysis that the heat release rate of 60% bioethanol combustion ranged from 20 to 140 kW/m2, while a lesser range resulted from 70% bioethanol combustion (18–45 kW/m2). The flame temperature for 60% bioethanol was found to be 440°C, while the smoke and orifice temperature was 150°C. The combustion of 70% bioethanol produced a flame temperature of 450°C and a smoke and orifice temperature of 120°C after approximately 6 min of combustion. This study contributes a solution for meeting the energy demand in rural areas, where the access to and availability of major fuel resources are limited. In addition, from the obtained results, this research concluded that bioethanol made from sago waste is suitable as a clean and alternative fuel for household applications in rural areas.

The frequent forest fires become a serious threat to the performance of transmission lines’ external insulation, therefore, researches on the breakdown characteristics under flame conditions is of great significance for the transmission lines' construction and safe operation. In order to study the breakdown characteristics of the gap under forest fire, the discharge tests of conductor-plane gap were carried out by the simulation forest fire experiment platform here, and typical vegetation causing the line tripping out easily were selected to simulate the forest fire. The influences of combustion features such as flame temperature, height, conductivity, and heat release rate were analysed too. The results show that the effect of different types of vegetation flame on breakdown characteristics of gap is obviously different, especially under the fir branches flame, the average breakdown voltage gradient drops to 10% of that of the pure air gap. The flame temperature has a minimal impact on the gap breakdown characteristics, while the conductivity has a significant influence on the insulation strength of the gap.

Research on alternative energy today based on issues of global warming and greenhouse effects. The use of coal briquettes from low-calorie coal derived from mines in the province of South Sumatera originally destined for the food industry is less desirable because it emits black and smelly smoke, is difficult to turn on, and it is difficult to shut down quickly. So the thought arises to use this coal briquettes for the manufacturing industry and metal casting. In a previous study, the manufacture of mixed briquettes between low calorie coal (lignite) and biomass was more environmentally friendly due to low sulfur content. Therefore, in this study, a study was conducted to find the best biomass species to be mixed with lignite to bio-coal with the highest carbon content criteria and lowest sulfur content. The results showed that the mixture type between coconut shell and lignite reached the optimum condition with carbon content of 57.923% and the lowest sulfur was 0.259% in the mixture ratio of 9 : 1. The combustion temperature reaches 1500 K at furnace efficiency of 48%.

Various kinds of pilot burners were experimentally investigated to examine the effects of their geometry and their location relative to the main burner of a real size combustor. In addition, a wide range of fuel equivalence ratios were investigated to analyze the feasibility of the novel pilot burner for the conventional burner application. From the results, it is shown that the novel pilot burner with multi air holes had a thin, straight, long and stable pilot flame, while the conventional pilot burner had a thick, lifted, short and unstable flame. It is also shown that the novel pilot burner with an upper air flow hole had a straight pilot flame which led to less thermal damage to the burner combustor. This study suggests that not only pilot burner flame shape but also the vertical location of the pilot burner from the main burner combustor has a significant effect on combustor durability.

Emissions from diesel engines can be limited and potentially decreased by modifying the fuel chemical composition through additive insertion. One class of additives that have shown to be particularly efficient in the reduction of the particulates from the combustion of diesel fuels are oxygenated compounds. In the present study we investigate the effect of tripropylene glycol methyl ether (TPGME) and two polyoxymethylene dimethyl ethers (POMDME or OMEs) on soot formation in a laminar diesel diffusion flame. From the evaluation of soot volume fraction by laser-induced incandescence (LII) measurements we could observe that OME additives have a substantial capability (higher compared to TPGME) to decrease the particle concentration, which drops by up to 36% with respect to the pure diesel fuel. We also note a reduction in particle aggregate size, determined by wide-angle light scattering (WALS) measurements, which is more pronounced in the case of OME–diesel blends. The effects we observe can be correlated to the higher amount of oxygen content in the OME molecules. Moreover, both additives investigated seem to have almost no impact on the local soot temperature which could in turn play a key role in the production of soot particles.

Premixed combustion of lean methane–air in an artificial porous media burner with staggered alumina cylinders was experimentally and numerically performed. Numerical simulations were conducted at gas mixture velocities of 0.43–0.86 m/s and equivalence ratios of 0.162 and 0.243, respectively. Through comparison with experimental results, temperature distribution, peak temperature and flame propagation velocity are analyzed and discussed in detail. The numerical calculated temperature profile over the axis of the combustor coincided well with test data in the post-flame zone, however a certain deviation was found in the preheated zone. A two-dimensional flame shape was observed and the flame thickness was the size of cylinder diameter. The peak temperature increased with the gas mixture inlet velocity at the certain equivalence ratio, and its peak value was about 1.8–2.16 times higher than the adiabatic combustion temperature under the desired equivalence ratio, which indicates that super-adiabatic combustion was the case for all the numerical simulations. The flame propagating velocity had a positive correlation with the gas mixture inlet velocity.

In this study, the turbulent non-premixed methane-air flame is simulated to determine the effect of air velocity on the length of flame, temperature distribution and mole fraction of species. The computational fluid dynamics (CFD) technique is used to perform this simulation. To solve the turbulence flow, k-ε model is used. In contrast to the previous works, in this study, in each one of simulations the properties of materials are taken variable and then the results are compared. The results show that at a certain flow rate of fuel, by increasing the air velocity, similar to when the properties are constant, the width of the flame becomes thinner and the maximum temperature is higher; the penetration of oxygen into the fuel as well as fuel consumption is also increased. It is noteworthy that most of the pollutants produced are NOx, which are strongly temperature dependent. The amount of these pollutants rises when the temperature is increased. As a solution, decreasing the air velocity can decrease the amount of these pollutants. Finally, comparing the result of this study and the other work, which considers constant properties, shows that the variable properties assumption leads to obtaining more exact solution but the trends of both results are similar.

The effect of simplified chemical kinetic model on the micro-flame structure, central axis and wall temperatures were investigated with different one-step global chemical kinetic mechanisms following Mantel, Duterque and Fernández-Tarrazo models. Numerical investigations of the premixed methane-air flame in the micro-channel and lean conditions were carried out to compare and analyze the effect of the comprehensive chemical kinetic mechanisms. The results indicate that one-step global chemical kinetic mechanism affects both the micro-flame shape and the combustion temperature. Among three simulation models, Mantel model allows a stable micro-flame with a bamboo shoot form, which anchor at the inlet. Duterque model gives a stable elongated micro-flame with a considerable ignition delay, and a dead zone with fluid accumulation is observed at the entrance, which may explain the very high combustion temperature and the fast reaction rate obtained, despite the micro-flame development presents a very hot spot and causes a broadening of the combustion zone. Fernández-Tarrazo model results in a rapid extinction and doesn't seem to take all the kinetic behavior into account for the appropriate micro-combustion simulations.

The aging of explosive charges in pyrotechnic mechanical devices (PMDs) significantly affects the reliability of their performance. Aging decreases the explosive power of explosive charges via pre-oxidation by external sources of oxygen. In this study, the flame temperature was calculated based on the amount of added oxygen source, and the effect of aging was quantified in terms of the performance of explosive charges. Three primary explosive charges (THPP, ZPP, and BKNO3) were selected, and the explosion was assumed to have occurred in a closed adiabatic system. The flame temperature decreased with increasing oxygen addition, suggesting that the aging decreased the pressure exerted by the PMDs. The explosive power decreased in the following order: ZPP >> THPP > BKNO3 (4100 >> 3260 > 3050 K), and it was decreased by aging as follows: ZPP >> BKNO3 > THPP (802 >> 219 > 95 K per mole of added water). As a result, ZPP is appropriate for the generation of the huge thrust of PMDs despite its increased susceptibility to aging, while THPP is superior for reliable PMD performance.

The structure of a counterflow-type cylindrical diffusion flame was studied experimentally to determine the effect of stretch and curvature. The cylindrical flame used in this study had a concave curvature with respect to the fuel stream. The fuels used were propane and methane, diluted with nitrogen, argon or helium. Diluent gases were used to change the Lewis number, Lef, of the fuel. Our results indicated that (1) the fuel was preheated to a high temperature by the concentric inward heat flow from the flame because the flame shape is concave curvature with respect to the fuel flow; (2) at constant flame stretch, flame temperature increased with a decrease in flame radius when Lef > 1, but decreased when Lef < 1; and (3) at constant flame radius, flame temperature decreased with increased flame stretch rate when Lef > 1, but increased when Lef < 1.

This paper reports a CFD modeling study to investigate the hydrogen-air mixture combustion in a micro scale chamber. Nine species with nineteen reversible reactions were considered in the premixed combustion model. The effect of operational and geometrical conditions including; combustor size, wall conductivity, reactant flow rates and hydrogen feed splitting on combustion stability and outlet gas temperature were investigated. The results show that the wall thermal conductivity has a significant effect on the combustion especially at smaller chamber size with high ratio of chamber surface area to its volume. In addition, the results reveal that high heat loss from chamber wall, small chamber and high input rate may cause flame quenching. Moreover, the modeling results indicate that a stable combustion in a micro combustor can be achieved at an optimum operational condition.

Analysis of the recorded image by a digital video camera of the Sm0.95CoO3-δ combustion synthesis is carried out. Intrinsically the combustion method yields nanometric materials (ceramic and metal-ceramic); allowing to produce catalytic powders. In this work, nanocrystalline powders of around 5 nm with 24 m2/g of specific surface area and, consequently, high reactivity powders were obtained. Preliminary studies were done about ignition step of the synthesis, using image analysis from the three primary colours planes decomposition, these experiments show that the generated flame in this ignition step is a thermodynamically random process. The final aim of this work is to establish a protocol of performance to a future correlation among relevant combustion synthesis parameters of materials, i.e. the precursors nature and concentration, and the temperature distribution during the ignition, to optimise and control the process. This investigation opens an important field, the use of image analysis to carry out a thorough study of the temperature evolution and of the flame intensity during the ignition step of a material combustion synthesis.El análisis de la imagen obtenida por una cámara de video digital se utiliza para el estudio de la reacción de síntesis por combustión de Sm0.95CoO3-δ. El método de combustión presenta como característica intrínseca la generación de materiales nanométricos cerámicos y metal-cerámicos; permitiendo la producción de compuestos con actividad catalítica. En este trabajo se obtienen polvos de tamaño de cristalito entorno a 5 nm, con una superficie específica de 24 m2/g y como consecuencia bastante reactivos. Se llevaron cabo estudios preliminares sobre la etapa de ignición de la síntesis usando el análisis de imagen por descomposición de los planos de los tres colores primarios; dichos experimentos muestran que la llama generada en esta etapa de ignición es un proceso termodinámicamente aleatorio. La finalidad de este trabajo es establecer un protocolo de experimentación para la futura correlación entre los parámetros de la síntesis por combustión de un material, naturaleza y concentración de precursores entre otros, y la distribución de temperatura durante la ignición, con objeto de optimizar y controlar el proceso. Se abre una línea de investigación basada en la utilización de la técnica de análisis de imagen para realizar un seguimiento controlado de la evolución de la temperatura e intensidad de la llama durante la etapa de ignición de la síntesis por combustión de un material.

This paper presents experimental investigations of the in situ diagnosis of the alkali metals in the municipal solid waste (MSW) flame of an industrial grade incinerator using flame emission spectroscopy. The spectral radiation intensities of the MSW flame were obtained using a spectrometer. A linear polynomial fitting method is proposed to uncouple the continuous spectrum and the characteristic line. Based on spectra processing and a non-gray emissivity model, the flame temperature, emissivity, and intensities of the emission of alkali metals were calculated by means of measuring the spectral radiation intensities of the MSW flame. Experimental results indicate that the MSW flame contains alkali metals, including Na, K, and even Rb, and it demonstrates non-gray characteristics in a wavelength range from 500 nm to 900 nm. Peak intensities of the emission of the alkali metals were found to increase when the primary air was high, and the measured temperature varied in the same way as the primary air. The temperature and peak intensities of the lines of emission of the alkali metals may be used to adjust the primary airflow and to manage the feeding of the MSW to control the alkali metals in the MSW flame. It was found that the peak intensity of the K emission line had a linear relationship with the peak intensity of the Na emission line; this correlation may be attributed to their similar physicochemical characteristics in the MSW. The variation trend of the emissivity of the MSW flame and the oxygen content in the flue gas were almost opposite because the increased oxygen content suppressed soot formation and decreased soot emissivity. These results prove that the flame emission spectroscopy technique is feasible for monitoring combustion in the MSW incinerator in situ.

Emulsion fuel is regarded as one of the possible fuels for reducing the emissions of pollutants from combustion systems. This study investigated the effect of droplet size on combustion and emission characteristics for both pure diesel and emulsion fuel in preheated ambient air. A burner equipped with a twin fluid atomizer was used to vary Sauter mean droplet diameter (SMD) of spray. Water percentage of 5 and 10 vol% in W/O emulsion fuel was used. Experimental results show that both emulsion fuel had lower EICO2 than diesel fuel. This result shows combustion efficiency of emulsion fuel was lower than that of diesel fuel. As the preheated ambient air temperature TAmbi was increased to 473 K, combustion efficiency of emulsion fuels was improved. In emulsion fuel combustion, NO emission was lower than pure diesel fuel combustion. The vaporization of water in emulsion fuels reduced local flame temperature and thus reduced the NO formation. Smaller fuel droplet SMD had higher NO emission for pure diesel fuel. However, NO emission had no dependence on fuel droplet SMD for emulsion fuel. Emulsion fuels also had lower flame luminance as compared with diesel fuel alone. This is caused by lower soot emission of emulsion fuels.