Combustion Analysis Research Articles

Phosphorescent Platinum(II) Complexes with a Spiro-fused Xanthene Unit: Synthesis and Photophysical Properties.

Novel platinum(II) complexes, derived from the spiro[fluorene-9,9'-xanthene] (SFX) motif, were synthesized and combined with different auxiliary ligands such as acetylacetonate (acac), bis(2,4,6-trimethylphenyl)propane-1,3-dionate (mesacac) and dihydrobis(3,5-dimethylpyrazole-1-yl) borate. The final products were obtained in yields of up to 36 % and characterized by NMR, X-ray and combustion analysis. These complexes have structured green-blue emission spectra with Commission Internationale de l'Éclairage (CIExy ) coordinates of (0.21;0.46). Excellent photoluminescence quantum yields (PLQYs) ranging from 87 %-91 % were found. The emission lifetimes vary from 33 μs to 43 μs. Calculations on the B3LYP/6-311++G** level of theory reveal, that the nature of the emissive state is dependent on the positional regioisomerism of the SFX motif. The 2-SFX complexes demonstrate ligand-centered (3 LC) emission, while the 2'-SFX regioisomer with the mesacac ligand shows a strong 3 MLCT character.

Numerical analysis of flow and combustion of Coal-Ammonia blend in coal-fired furnace

Co-firing ammonia (NH3) in coal-fired power plants presents an attractive method to expedite the global decarbonization process. Nevertheless, the challenge lies in reconciling the need for higher temperatures within the furnace with the imperative of maintaining low nitrogen oxides (NOx) emissions, which limits the widespread use of NH3 as a fuel. In this article, the flow and combustion of coal-NH3 blends in a 3 × 700 MW tangentially-fired utility coal boiler furnace are investigated using Computational Fluid Dynamics (CFD). The impact of NH3 blending ratios is examined through numerically simulated combustion involving five co-firing ratios (CRs) of NH3, including 0%, 10%, 20%, 30%, and 50%. Various combustion properties are assessed, including the furnace’s temperature profile, flow distribution, species emissions, pollutant formation, and heat generation. To validate the approach, single coal and coal blend simulations performed depicted reasonable agreement in predicting furnace flame temperatures. The predicted flue gas temperature exhibited a decrease with an increase in NH3 CR, leading to a reduction in the furnace’s heat generation. Regarding flow characteristics, there was a notable increase in velocity as the concentration of NH3 was raised. The elevated NH3 content correlated with an observed rise in oxygen (O2) residue in the rear pass, coupled with a decrease in both carbon dioxide (CO2) and carbon monoxide (CO) concentrations. Pollutant formation, assessed in terms of nitrogen oxide (NO) emissions, revealed an increase in concentration with the rise in NH3 CR. Indeed, these findings suggest a promising strategy for adopting NH3 as a viable alternative to coal, representing an effective carbon-neutral fuel for the future.

Si-N Matrix as an Effective Fire Retardant Source for Cotton Fabric, Prepared through Sol–Gel Process

In this study, process control factors such as dipping time, heat treatment time and curing conditions were optimized to prepare N-Si network sol–gel-based coatings on a cotton fabric. The dipping time was varied from 14 h to 30 min, the heat treatment time at ~90 °C was varied between no heating conditions to 15 h and the curing was performed at 165 °C. The microstructure of the coating was analyzed using low electron scanning microscopy (LV-SEM), while a compositional study of the coated substrate was carried out using FTIR and EDS techniques. From the thermal and combustion analysis of the coated samples using thermogravimetric and vertical flame test techniques, significant resistance to the degradation process was observed, particularly in the initial stages, in addition to the highest char residue for DI-0.5 h-15~32.93%. Similarly, for DI–5 h–RT, the peak degradation temperature was around ~372 °C, accompanied by a notable char residue of approximately 31.12%. The flame spread and burning rate profile further supported the findings; DI-0.5 h-15 and DI-5 h-RT had the lowest flame spread.

Biodiesel Blends for Eco-Friendly CRDI-VCR Engines: Enhancing Exhaust Emissions and Engine Performance to Minimize Pollutant Emissions

<p>Energy is essential but associated with global greenhouse emissions. Therefore, clean and renewable energy is important for future development. To meet this demand, kapok oil methyl ester (KOME) was made from the kapok raw oil through the transesterification method. KOME was then combined with diesel in the ratios of 10%, 20%, and 30% (v/v%) to form KOME10, KOME20, and KOME30 mixtures. The combustion and emissions outcomes of KOME blends were studied at a stationary DI engine under different loads and modified common rail direct injection (CRDI) mode at 400 bar injection pressure, partial load, and CR of 19:1, 20:1, and 21:1. The combustion analysis of blends like maximum pressure (Pmax) and net heat release rate (HRRmax) were observe lesser than diesel at stationary mode, whereas they increased by 13–15% and 16–32% in CRDI mode, respectively. Exhaust from engine such as carbon dioxide, hydrocarbons, and smoke were decreased, but nitric oxide increased about 0.7–1.5% and 1.3–8% for stationary and CRDI modes, respectively, as compared to diesel. This concludes that KOME might be a suitable substitute to diesel fuel for non-road DI engine applications.</p>

Predict the characteristics of diesel engine using glycine max oil biofuel

Significant research is devoted to the transformation of Glycine max oil (soybean oil) into biofuel. An exhaustive investigation into the performance, combustion and emission analyses of glycine max oil biofuel (GMOB) in the context of optimization studies involving variable engine factors such as load, injector timing and so forth, has yet to occur. This study endeavors to fill the gap in the academic literature regarding comprehensive engine investigations of GMOB. In this study, five distinct mixtures of GMOBs are combined with diesel: DS1—0% biofuel with 100% diesel, DS2—5% biofuel with 95% diesel, DS3—20% biofuel with 80% diesel, DS4—40% biofuel with 60% diesel and DS5—100% biofuel and 0% diesel. Using standard ASTM limits, the properties of the biodiesel samples were evaluated and confirmed (the kinematic viscosity at 40°C for GMOB is 4.6 mm2/s, whereas that of unadulterated diesel is 3.0 mm2/s). Utilizing the combustion, emission and performance characteristics of a compression ignition engine, the blend, load and injection timing (IT) were optimized. At 100% load, an upward trend in indicated thermal efficiency is observed for both diesel and biofuel blends. Furthermore, the volumetric efficiency of all biofuel blends was enhanced through the implementation of advanced IT (24.5° b TDC). Additionally, smoke emission is observed to increase by 18.5°–24.5° b TDC across all mixtures. Biofuel mixtures exhibit a negligible minimum rate of pressure increase per degree.

Analysis of Calophyllum Inophyllum Biodiesel Combustion with Variations of Magnetic Field Strength

The problems facing the world today are limited fossil fuels and increasing global warming due to fuel emissions. Therefore, there is a need to transition from fossil energy to alternative energy that is environmentally friendly and renewable. Biodiesel is an alternative material that can be used as a substitute for diesel fuel. This research aims to improve the combustion quality of calophyllum inophyllum biodiesel using the magnetic field influence method. The combustion test method uses a Bunsen burner and variations in magnetic strength of 4000 gauss, 8000 gauss and 12000 gauss are given. The equivalent ratios used in combustion analysis are 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1:1.1, and 1:1.2. The fuel and air flowing in the Bunsen pipe are heated to a constant temperature of 250°C for the fuel evaporation process. Then the resulting flame was analyzed for its combustion characteristics with RGB color variables, laminar burning velocity, and flame height. The research results show that the stronger the magnetic field effect, the more optimal the combustion quality will be. This is indicated by the increasingly strong magnetic field effect exerted on the flame, causing the red color intensity to decrease, the laminar burning velocity to increase, and the flame height to decrease. This is because the magnetic field can influence the movement of O2 molecules and cause a change in the orientation of the hydrocarbon from para to ortho. As a result, diffusion combustion becomes minimal and the combustion reaction becomes faster.

Improvement of worsened diesel and waste biodiesel fuelled-engine characteristics with hydrogen enrichment: A deep discussion on combustion, performance, and emission analyses

Due to the strict emission policies, fuel researchers are dedicated to mitigating the tailpipe emissions from internal combustion engines (ICEs). Therefore, researchers have considered biodiesel as the best alternative to conventional diesel fuel (D) for a while. However, many scientific papers experimentally announced that the use of biodiesel significantly worsens engine behaviors. In this framework, hydrogen enrichment has become a very reasonable option in order to minimize the reverse influences of biodiesel-fuelled engine characteristics. In this direction, waste cooking of 25% (B25) was volumetrically blended to D and reference data was collected. Then, 15 and 30 Lpm hydrogen was introduced from the intake manifold by mixing with air along with B25 test fuel to observe the changes from the hydrogen effect. Tests were performed on a three-cylinder, water-cooled diesel engine at constant engine speed (2000 rpm) and variable engine loads (15, 30, 45 and 60 Nm). In the results, it is witnessed that BSFC (brake specific fuel consumption) for B25 fuel increased by 8.23% as compared D fuel. However, along with the introduction of 15 and 30 Lpm hydrogen to B25 fuel, the BSFC value dropped by 17.58%, and 30.75%, respectively. In a similar way, B25 test fuel reduces BTE (brake thermal efficiency) by 7.54% as compared to D fuel. However, the hydrogen introduction of 15 and 30 Lpm (Litre per minute) along with B25 fuel improves the BTE value by 10.19%, and 17%, respectively. On the other hand, the inclusion of 15 Lpm and 30 Lpm H2 to B25 fuel provided a reduction of 23.75% and 45.59% for HC (Hydrocarbon) emissions, and 53.1% and 62.6% for NOx (Nitrogen oxide) emissions, respectively. In conclusion, it is seen that deteriorations in combustion, performance, and emission characteristics resulting from the use of biodiesel can be minimized by using hydrogen for ICEs.

Hydrogen mixing and combustion in an SI internal combustion engine: CFD evaluation of premixed and DI strategies

In this study, the effect of start of injection (SOI) timing is investigated on a single cylinder spark ignited (SI) internal combustion engine (ICE) fueled with hydrogen, using Computational Fluid Dynamics (CFD) simulations. Mixing fields and combustion behaviors at different relative air-fuel ratios (λ) and injection strategies are discussed. Direct injection (DI) cases with three different SOI timings for each λ are compared against port-fuel injection (PFI) cases modeled assuming perfectly premixed charge at the intake plenum. Results for the investigated cases show that PFI cases at λ = 2 and λ = 3 have very high combustion efficiency while at λ = 3.5 partial burn occurs (only 70% of the fuel is oxidized). In DI cases, combustion efficiency decreases compared to corresponding premixed situations, as expected, but significant improvements are obtained by advancing the SOI timing towards the end of the intake stroke. In addition, early SOI timings tend to reduce the duration of initial combustion stage, CA0-10, which correlates with ignition repeatability, therefore suggesting potential benefits on combustion stability under very lean conditions. The method and results of this work can be used as a guideline for developing efficient hydrogen injection strategies.

Effect of methane injection strategy on combustion, exergetic performance, and enviro-economic analyses in a diesel/methane CRDI engine

To assess the applicability of methane gas in the context of a methane injection strategy in dual fuel concept, it is crucial to evaluate not only the engine performance but also the exergetic performance and the enviro-economic analyses. In this experimental study, a comprehensive investigation was performed to explore the impacts of a methane injection strategy, involving the timing and quantity of methane gas injection, on the combustion and emission characteristics of a diesel/methane dual-fuel operation. Also, an assessment of energy, exergy, environmental impact, and cost analyses on methane injection strategy using data obtained from experimental results was performed. In the literature, there is a deficiency regarding the evaluation of methane injection strategy in terms of energy, exergy, and enviro-economic analyses. This study will not only address the current research gaps but also serve as a reference for future investigations. The experiments were conducted on a single-cylinder, air-cooled, diesel engine with a common rail fuel system, operating at a fixed engine speed and load. In the experiments, methane injection timing (MIT) was advanced from 20 CAD aTDC to 60 CAD aTDC in 10 CAD increments. The methane injection duration (MID) was increased from 2 ms to 4 ms in 0.5 ms increments. The results have demonstrated that delaying the MIT increases combustion stability compared to early MIT and shortens ignition delay time. High HC and CO emissions resulting from early MIT have been reduced by up to 26 % and 19 %, respectively, with the delay of MIT. Through the delayed MIT application, the diesel/methane study yielded higher exergetic efficiency, lower exergy destruction, and entropy generation compared to the only-diesel operation. Additionally, lower environmental impact and cost values were obtained due to combustion at lower temperatures compared to diesel.

A numerical analysis of hydrotreated vegetable oil and dimethoxymethane (OME1) blends combustion and pollutant formation through the development of a reduced reaction mechanism

The solution to the dilemma of carbon footprint of internal combustion engines and pollutant emissions is necessary for the survival of this technology. In this context, alternative fuels have shown great potential in terms of achieving cleaner combustion and compliance with ever increasing pollutant emissions regulations. This work is focused on the study of two promising alternative fuels as Hydrotreated vegetable oil (HVO), which is a biofuel and Dimethoxymethane also termed as OME1, which is an e-fuel. A comprehensive numerical approach has been followed to study these fuels. Primarily a compact reaction mechanism having 121 species and 678 reactions has been developed which can be utilized to perform 3D CFD simulations of blends of these fuels. Secondly, a detailed numerical investigation including combustion and emissions analysis has been carried out. Results show that the developed mechanism is able to offer predictions, which match the experimental behavior observed in various combustion parameters and thus can be utilized for compression ignition engine applications involving these promising fuels. In addition, the numerical analysis also highlights that a reduction of 50% and 37% in terms soot and NOx emissions respectively can be achieved by addition of 30% OME1 in the blend containing HVO, suggesting that these blends can be utilized in unmodified CI engines to break the soot-NOx tradeoff without significantly penalizing the energy loss.

Electrochemical Analysis of Metal Stability in Candidate Reference Electrode Fluoride Salts (FLiNaK + 1 wt% AgF, MnF2, or NiF2)

This paper investigates the long-term stability of Ag/AgF, Mn/MnF2, and Ni/NiF2 redox couples for use in reference electrodes (REs) for molten fluoride salt systems such as molten salt reactors. A quasi-RE system was used with FLiNaK + 1 wt% AgF, MnF2, or NiF2, to evaluate the stability of various metals that may be used as the reference electrode body, reference internal element, or membrane for a molten fluoride salt RE design. Cyclic voltammetry was used to measure changes in the electrochemical response of different metal wires in the melts tested. Salt samples were analyzed for dissolved metal concentrations and oxide concentrations via inductively coupled plasma mass spectroscopy and combustion analysis, respectively. To observe the surface morphology of the electrodes used in the Ag/AgF test, cross-sectional imaging of the electrodes was provided via scanning electron microscopy (SEM). The resulting electrochemical measurements show that a RE constructed using a Mn/MnF2 or Ni/NiF2 redox couple should perform with greater potential stability compared to a Ag/AgF redox couple. The instability of the Ag/AgF redox couple is due to the strong oxidizing property of the AgF salt with metals compared to the MnF2 and NiF2 salts. The SEM results from the Ag/AgF test indicate that Ag metal is corrosion resistant, but having AgF in the salt causes it to be corrosive towards other metals (Ni and W) that are considered relatively corrosion resistant in molten salts.

Chemical Kinetic Analysis of High-Pressure Hydrogen Ignition and Combustion toward Green Aviation

In the framework of the “Multidisciplinary Optimization and Regulations for Low-boom and Environmentally Sustainable Supersonic aviation” project, pursued by a consortium of European government and academic institutions, coordinated by Politecnico di Torino under the European Commission Horizon 2020 financial support, the Italian Aerospace Research Centre is computationally investigating the high-pressure hydrogen/air kinetic combustion in the operative conditions typically encountered in supersonic aeronautic ramjet engines. This task is being carried out starting from the zero-dimensional and one-dimensional chemical kinetic assessment of the complex and strongly pressure-sensitive ignition behavior and flame propagation characteristics of hydrogen combustion through the validation against experimental shock tube and laminar flame speed measurements. The 0D results indicate that the kinetic mechanism by Politecnico di Milano and the scheme formulated by Kéromnès et al. provide the best matching with the experimental ignition delay time measurements carried out in high-pressure shock tube strongly argon-diluted reaction conditions. Otherwise, the best behavior in terms of laminar flame propagation is achieved by the Mueller scheme, while the other investigated kinetic mechanisms fail to predict the flame speeds at elevated pressures. This confirms the non-linear and intensive pressure-sensitive behavior of hydrogen combustion especially in the critical high-pressure and low-temperature region which is hard to be described by a single all-encompassing chemical model.

Advanced Numerical Analysis of In-Cylinder Combustion and NOx Formation Using Different Chamber Geometries

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.

Laminar flame stability analysis of ammonia-methane and ammonia-hydrogen dual-fuel combustion

In recent years, dual-fuel combustion of ammonia blended with reactive fuels like methane or hydrogen has gained attention for reduced carbon emissions. This study investigates the stability of NH3-CH4 and NH3-H2 laminar propagating flames, utilizing experimental and numerical methods. It covers an extensive span of equivalence ratios (0.7–1.6), fuel compositions, and a variety of initial temperatures (300–600 K), as well as pressures ranging from 1 to 5 bar·NH3-CH4 blends exhibit stability across all equivalence ratios, with Markstein lengths of 0.02–2.49. In contrast, NH3-H2 flames display significant variations in Markstein lengths, ranging from 3.73 to −3.36 at an equivalence ratio of 0.7, particularly destabilizing fuel-lean flames due to heightened preferential-diffusional instabilities. Increasing ammonia content stabilizes fuel-rich flames but destabilizes fuel-lean ones. As ammonia content rises, both NH3-CH4 and NH3-H2 flames become more hydrodynamically stable due to flame thickening, although this can exacerbate flame instabilities when preferential-diffusional instabilities dominate. Additionally, preheating destabilizes both ammonia-methane and ammonia-hydrogen flames hydrodynamically, while pressure affects NH3-CH4 and NH3-H2 mixtures oppositely, destabilizing the former and stabilizing the latter due to reduced flame thickness. The addition of diluents stabilizes NH3-CH4 flames but destabilizes NH3-H2 flames, influencing Le and Ze numbers. Diluent addition significantly reduces the flame temperature gradient (up to 64 %), resulting in thicker flames and enhanced hydrodynamic stabilities. This research provides insights into the complexities of ammonia-blended dual-fuel combustion and its impact on flame stability under various conditions.

OpenFOAM mechanical simulations for confronting structural challenges and attaining high-fidelity results

Multi-dimensional models are now a unified collection of tools for simulating the combustion process in internal combustion engines. To address key challenges in combustion technology and to advance our ability to predict, control, and optimize combustion processes through a novel and integrated approach. In this direction, the present study emphasizes the integration of advanced computational fluid dynamics (CFD) techniques with OpenFOAM to conduct a comprehensive analysis of laminar combustion inside the intake manifold. This integrated approach offers a unique and holistic perspective on combustion processes, a perspective that has not been extensively explored in prior research. Furthermore, FVM is introduced as a novel methodology for the efficient and accurate simulation of these multi-physical phenomena, thereby contributing to the advancement of combustion modeling. The analysis focuses on the flammable energy, energy deposition, and combustion inside the intake manifold of an engine. The goal is to create a comprehensive model that accounts for the intricate interactions between thermal energy, velocity, and species concentration, ultimately leading to a deeper insight into combustion phenomena. The maximum flammable energy is observed near the outlet of the considered intake manifold.

Modeling the co-combustion of bi-fuel blends in a drop tube furnace: A numerical approach

The present study focuses on the numerical modeling of the co-combustion of reject coal (RC) and sal leaves (SL) in a drop tube furnace (DTF) under different conditions, including air-fuel and oxy-fuel environments. The numerical results highlight the significant influence of replacing the N2 atmosphere with CO2 on the temperature profiles of individual fuels and their blends. For instance, when exposed to a 21%O2/79%CO2 atmosphere, Blend SL3 and Blend SL5 experience a decrease in temperature from 1372 K to 1559 K to 1327 K and 1395 K, respectively. Conversely, increasing the O2 concentration to 35% leads to a temperature rise. Furthermore, the combustion analysis reveals that the addition of 10% SL to RC in a 21%O2/79%N2 environment enhances the devolatilization rate from 1.41 × 10−12 kg/s to 1.77 × 10−12 kg/s. Additionally, the char combustion process for all blends is completed closer to the DTF inlet at 0.28 m, compared to 0.32 m for RC alone. These findings indicate that blending SL with RC promotes a favorable combustion process. Moreover, increasing the O2 concentration to 35% in oxy-fuel conditions enhances the temperature profiles. The numerical analysis demonstrates good agreement with experimental data within a range of ±5%–11%. This suggests that the developed model can be effectively utilized for optimizing and designing biomass co-firing systems in industrial applications, considering both air-fuel and oxy-fuel conditions.

Analysis of combustion and heat transfer performance in a slit-type fully premixed burner

Since most gas water heaters on the market still use diffusion or partially premixed combustion. Fully premixed combustion, with its advantages of complete combustion and low CO and NOx emissions, offers a promising alternative. In response to this, a slit-type fully premixed gas water heater with a rated power of 20 kW was designed. The combustion and heat transfer performance, as well as the combustion temperature and burnout characteristics, were analyzed under ten different load conditions ranging from 100% to 8% using theoretical modelling. The study identified the variations in physical parameters and used numerical simulations to partially validate the theoretical results. Subsequently, by individually modifying structural variables, the optimal structure under single-variable conditions was determined. This optimal structure was then combined in various configurations to form a multi-variable structural design. Further theoretical analysis was conducted to assess whether the changes in the multi-variable structure, as well as the original design, met economic efficiency requirements. The results showed that the slit-type fully premixed burner achieved optimal performance when the number of burner plates was 120, with a length of 99 mm and a height of 10 mm.

Removal of carbon monoxide from an ambient environment using chicken eggshell

Adsorbents from chicken eggshells were synthesized by a simple method and used as a novel and effective adsorbent for the removal of carbon monoxide (CO) from an ambient environment. The synthesized adsorbents were characterized by X-ray fluorescence (XRF), Atomic absorption spectroscopy (AAS), Fourier transform infrared spectroscopy (FTIR), Proximate, ultimate analysis and adsorption isotherms. The characterization results showed that the presence of Ca, CaO, SiO2, CO, O-H, and O-Si-O stretching vibration bonding contributed to the adsorption capacity of the synthesized adsorbents. Chicken eggshells were collected, washed, and dried before being pulverized and sieved to yield 36 µm mesh particles. The eggshells were then separated into parts and treated to various calcination temperatures (700 °C, 800 °C, and 900 °C) with and without phosphoric acid impregnation. Therefore, seven different adsorbents were synthesized. An environmental chamber with a portable generator as the CO source was used to evaluate the performance of the adsorbent. For different residence times (2 to 10 min), different amounts of the synthesized adsorbents (varying from 5 g to 25 g) were introduced into the chamber. A combustion analyzer was used to measure the initial and final CO concentrations. All the synthesized adsorbents are effective in removing CO, but ordinary chicken eggshell has the highest (59.32%) CO capacity removal, the adsorption kinetics followed a Lagergren pseudo-first-order model, and the adsorption isotherms conformed to Langmuir equation.

System-level feasibility analysis of a novel chemical looping combustion integrated with electrochemical CO2 reduction

A schematic of an integrated polygeneration process combining chemical looping combustion with electrochemical CO2 reduction to produce electric power and ethylene.

Analyzing the ignition capabilities of glowing firebrand accumulations

Firebrand spotting is a significant mechanism for structure losses in wildland–urban interface (WUI) fires. In this work, the ability of firebrand accumulations to cause flaming ignition of an engineered wood material, Oriented Strand Board (OSB), under different flow conditions was experimentally studied. The firebrands were emulated by burning wooden dowels of two sizes, 6.35 & 12.7 mm. Firebrands were dropped onto on the fuel to form accumulations, with the coverage densities of 0.06 to 0.16g/cm2 on the fuel surface. The surface temperature of glowing combustion on the firebrands was measured with color ratio pyrometry. The ignition outcome results show a similar hyperbolic relationship between air flow and coverage density for both firebrand sizes although accumulations of small firebrands can cause the ignition faster. A firebrand combustion model was adopted to predict the surface temperature of accumulated firebrands considering re-radiation between nearby firebrands. A correlation between the ignition time and characteristics of accumulations was also established based on a theoretical combustion and heat transfer analysis.