Understanding hydrodynamic instabilities in coflow diffusion flames is essential for enhancing operational stability and safety. This study presents the first experimental investigation into the effects of pressure, flow rates, coflow/central jet velocity ratio, and O2 concentration on hydrodynamic instabilities in laminar normal and inverse diffusion flames (NDFs and IDFs). Methane (CH4) diluted with carbon dioxide (CO2) was used as fuel, whereas oxygen (O2) diluted with nitrogen (N2) was the oxidant. The spatial-temporal features of these flames were captured with a high-speed camera, luminous flame height was characterized for flame dynamics, and oscillation frequency was quantified using the Fast Fourier Transform (FFT) method. Results demonstrate that flame configuration significantly influenced instability modes. Unstable NDFs consistently exhibited the sinuous mode, while unstable IDFs were predominantly under the varicose mode. This distinct trend could be attributed to the density difference between the central jet and the coflow stream. Instability modes are found to be highly sensitive to the gas velocity and O2 concentration since these parameters could displace the point of toroidal vortices formation (upward displacement with higher coflow velocity and lower jet velocity) and affect the flame height (reduction at lower jet velocity or higher O2 concentration). Pressure had a minimal effect on the instability modes, although stable flames were mostly observed at higher pressures with high Recoflow. Instead, oscillation frequency increased with pressure in buoyancy-driven flames (Fr<1) but was more influenced by jet flow rate in momentum-driven flames (Fr>1). A power-law relationship between the non-dimensional numbers St and Fr was observed with two different slopes for momentum-driven flames (n<0.5) and for buoyancy-driven flames (n>0.5). A single correlation with Re described frequency behavior at each pressure level. These findings offer practical conditions for optimizing ATR burner stability.

Inverse co-flow diffusion flames (IDF) are the fundamental flame configuration in which autothermal reforming (ATR) of natural gas is based, a technology for clean hydrogen production. However, soot formation is unavoidable for IDFs because of fuel-rich conditions. This study assessed the effects of various diluents, including carbon dioxide (CO2), nitrogen (N-2), argon (Ar), and helium (He), introduced into the fuel stream on the properties of oxy-fuel laminar IDFs, with the aim of improving the understanding of soot formation in IDFs at atmospheric pressure. The flame structure, temperature, syngas (H-2+CO), polycyclic aromatic hydrocarbons (PAHs), and soot formation in methane IDFs were investigated using laser-based diagnostic techniques and numerical simulations. Pure oxygen (O-2) was used as an oxidizer to mimic the ATR process. Results show that diluent addition reduces the peak flame temperature and shifts the flame structure axially downstream, increasing the flame height due to buoyancy-induced acceleration and slower diffusion. OH-PLIF measurements reveal that CO2-diluted flames exhibit the longest flame lengths, linked to Peclet number (Pe) trends and suppressed buoyancy-driven radial convection. PAH formation follows the order: He > Ar > N-2 > CO2, with CO2 reducing PAH levels by promoting oxidation of key intermediates via increased OH production. Soot spatial distribution is shifted downstream, with the peak soot volume fraction (SVF) following Ar > N-2 > He > CO2, correlating with flame temperature and residence time. CO2 had the strongest soot suppression effect, acting through both thermal and chemical mechanisms. Numerical results indicate that temperature and OH mole fraction govern the syngas composition. CO2 dilution resulted in higher CO and lower H-2 production, as reaction pathway analysis showed that CO2 enhances OH and CO formation while reducing H radicals, limiting H-2 generation. These findings provide insights into the role of diluents in controlling soot and syngas formation in IDFs.

Autothermal reforming (ATR), which uses the inverse diffusion flame (IDF) configuration, is a promising technology to economically mass-produce hydrogen, which is seen as a key energy source in the future decarbonized society, from methane. Flame length is an important characteristic of IDFs, as it is used to validate theoretical, numerical and phenomenological models. In this work, the flame lengths of carbon dioxide-diluted methane IDFs were determined by OH* chemiluminescene. The effects of the fuel mole fraction, the oxidizer flowrate, and the oxygen mole fraction in the oxidizer stream on the flame length at the atmospheric pressure were assessed. Like normal diffusion flames (NDFs), the flame length of IDFs was primarily governed by the central jet flowrate but was moderately affected by the fuel mole fraction. Nonlinear relationships between the flame length and the oxygen mole fraction were found. The flame length peaked at a certain oxygen mole fraction, and then decreased at higher oxygen mole fractions. The flame lengths were also analytically predicted by Roper's correlation. It was found that the nonlinear trend could be due to a competition between the effect of stoichiometry and the effects of elevated flame temperature and promoted gas diffusivity. However, modified Roper's correlations proposed by previous studies failed to predict this nonlinear behavior. An empirical formula was proposed to estimate a term that is a function of characteristic flame temperature and diffusivity. A better first order prediction of the flame length was achieved.

The co-firing of ammonia (NH3) with hydrocarbon fuels is an effective strategy for reducing CO2 emissions and addressing the inherent low reactivity of NH3. However, soot formation presents a potential challenge in this context. In this study, experimental and numerical investigations are conducted to understand the chemical effect of NH3 on soot formation. Measurements of polycyclic aromatic hydrocarbons (PAHs) and soot volume fraction are performed in coflow diffusion flames with varying NH3 blending ratios (0-25 %), and this data was compared against numerical simulations. To improve the prediction of reduced PAH with NH3 substitution, an additional reaction of C3H3 and HCN is incorporated into the gas-phase mechanism. Moreover, a recently proposed reactive soot inception model is employed and the soot surface growth model is improved to account for the blocking of active sites on the soot surface by NH3 decomposition products (such as NH2). Simulations were conducted for counterflow and coflow diffusion flames. The results demonstrate that NH3 substitution leads to a decrease in H radical and an increase in H2. The improved models, which include the action of the H radical and nitrogen-containing species, provide better predictions of how soot volume fraction and mean particle diameter change with NH3 substitution, demonstrating the importance of C-N chemistry in both gas-phase and solid-gas reactions on PAHs and soot formation. Future work is needed to develop a more comprehensive C-N chemical pathways for predictions of co-firing of ammonia with hydrocarbon fuels.

Autothermal reforming (ATR) of methane is a promising technology for low-carbon H2 production due to its high CO2 capture efficiency (>95 %) and cost advantage. Especially, reforming CO2+CH4 greenhouse gases to valuable CO+H2 gases is a feasible solution for carbon-neutral energy systems. Flame temperature, reforming gas composition and concentration, and soot loading are major factors determining the efficiency of H2 production in the subsequent catalyst region. In this study, the effects of CO2/CH4 ratio on the profiles of temperature, OH radical, light gas products, large polycyclic aromatic hydrocarbons (PAHs), and soot were investigated for CH4-CO2-O2 laminar inverse diffusion flames near ATR conditions, using the combined non-intrusive and intrusive diagnostic methods. Pure O2 as oxidizer was fed through the central nozzle of the burner surrounded by CH4 fuel diluted with CO2. The experimental results revealed that the formation of soot and PAHs was greatly suppressed with a higher CO2/CH4 ratio. The PAHs and soot loading followed exponential function as CO2/CH4 mole ratio, regardless of pressure, O2 mole fraction, and burner size. The flame height was found to increase linearly with CO2 dilution, and the high temperature region (> 1000 K) shifts downstream. The H2 production decreased with CO2/CH4 ratio, while CO production is less sensitive to CO2 dilution. The importance of radical species during soot formation is confirmed based on the comprehensive data set. Moreover, five well-known chemical-kinetic mechanisms were evaluated against experimental datasets. The comparisons indicate that the flame temperature and concentration trends of investigated species are well predicted, but future work is needed to improve the prediction accuracy of amplitude and spatial distribution, especially for C2H2, PAHs and soot. The reported experiment and simulation results can provide valuable guidance for ATR model validation, development, reduction, and application.

The global extinction limits of non-premixed nitrogen/ammonia-substituted methane- and ethylene-air counterflow flames were experimentally evaluated. In comparison to nitrogen substitution, ammonia substitution reduced the extinction strain rates more. Measurements of OH* chemiluminescence, of which the intensity correlates with extinction limits, suggest that ammonia substitution reduces OH* production. The effects of transport, thermal and chemical properties on flame extinction of the ammonia-substituted flames were assessed, and it was found that their lower extinction limits were due to reactions that consume radicals, which hinder the chain-branching reactions. To mimic the effect of exhaust gas recirculation on the extinction limits of ammonia-substituted flames, carbon dioxide was added to the oxidizer stream. Lower extinction limits were observed with carbon dioxide addition as a result of thermal and chemical effects. Carbon dioxide addition lowered flame temperatures and, like ammonia substitution, introduced reactions that consume radicals. Nitric oxide (NO) production was quantitatively analyzed by simulations. It was found that, for ammonia flames, NO production was promoted by ammonia oxidation with OH, whereas for carbon dioxide addition, NO production was suppressed by the reduction of OH production.

Zero-carbon alternative fuels such as hydrogen and ammonia are gaining popularity. Blending these fuels with hydrocarbons is an intermediate approach to mitigate soot and carbon dioxide production. Recent studies have concentrated their attention to the effects of ammonia and hydrogen on the soot production of hydrocarbon fuels. It is still necessary to completely comprehend how this influence is dependent on the type of fuel and flame configuration. In this work, the effect of hydrogen and ammonia addition on soot production in ethylene laminar inverse diffusion flames (IDF) was numerically examined for the first time. The thermal, chemical, and combined effects of hydrogen and ammonia were assessed by fictitious species. The experimental results from the literature were used to validate the temperature and soot volume fraction profiles. Results indicated that the flame temperature and the production of radicals are promoted chemically by hydrogen addition but inhibited under the thermal effect of ammonia. The principal source of the reduction in OH-represented flame height, soot volume fraction, average diameter, and primary particle number density in the IDF is the thermal effect of additives, and hydrogen addition performs better than ammonia. The major and intermediate species, the aromatic hydrocarbons, and the soot formation or oxidation reaction rates are decreased mainly by the hydrogen and ammonia thermal effect while increased moderately by the chemical effect. Therein, the reduction in soot generation is mainly due to the polycyclic aromatic hydrocarbon condensation rate being slowed down by additives. The inhibition is attributed to the thermal effect of additions, and hydrogen behaves better than ammonia.

The effect of ammonia (NH3) addition on soot growth and inception is investigated in laminar co-flow NH3-ethylene (C2H4) diffusion flames. By comparing C2H4 flames with increasing% of NH3 by volume for the same carbon flow and flame height, the impact of NH3 addition on soot formation is identified. Experimental measurements of flame temperature, soot volume fraction, and primary particle sizes and number densities are compared with a numerical two-dimensional co-flow flame model to evaluate the contribution of NH3 to soot reduction in C2H4 flames. Experimental and numerical results show a significant reduction in the amount of soot formed and the diameter and the number of the primary particles suggesting reduced rates of soot growth and inception due to NH3 addition. The numerical model provides the understanding of how NH3 inhibits soot formation in the flame by analyzing the soot formation pathways and investigating the concentration of relevant gas phase species in the flame. While the impact of NH3 addition on the growth of soot particles is not fully captured by the model, the NH3’s reductive effect on the number of soot particles formed is well predicted. The results suggest that NH3 reduces soot by suppressing the concentration of methyl radicals which are responsible for forming odd numbered carbon species such as propargyl and cyclopentadiene. These species are found to be important contributors to the formation of large polycyclic aromatic compounds which are precursors of soot inception.

Carbon and metal-oxide nanoparticles (NP) are currently synthesized worldwide for various applications in the solar-energy, optical, pharmaceutical, and biomedical industries, among many others. Gas phase methods comprise flame synthesis and flame spray pyrolysis (FSP), which provide high efficiency, low cost, and the possibility of large-scale applications. The variation of combustion operation parameters exerts significant effects on the properties of the NPs. An analysis of the latest research results relevant to NP flame synthesis can provide new insight into the optimization of these methods and the development of these techniques for a large scale. This review offers insight into the current status of flame synthesis for carbon and metal-oxide NPs—specifically containing analysis and comparison of the most common carbon and metal-oxide NP production techniques. The burner configurations used at the laboratory scale and large scale are also discussed, followed by the assessment of the influence of combustion parameters on the properties of NPs. Finally, the features of the measurement techniques applied for determining NP properties were described.

The formation of soot in ammonia (NH3) combustion with a hydrocarbon such as ethylene (C2H4) is investigated using the analysis of particles' nanostructure and surface chemical composition to identify the mechanisms by which NH3 suppresses soot growth. Young and mature soot particles were extracted from laminar diffusion co-flow flames of NH3C2H4 blends up to 50% NH3. The soot nanostructure is examined using lattice fringe analysis of high-resolution transmission electron microscopy (HRTEM) images, Raman Spectroscopy, and Electron Energy Loss Spectroscopy (EELS). The chemical composition of the soot surface is analyzed using X-ray Photoelectron Spectroscopy (XPS). With increasing NH3 addition, reduced planar growth of the soot graphitic layers is observed through the analysis of the soot nanostructure which indicates the suppression of carbon addition at the edge sites of the layer planes. It is also found that the carbon sp2/sp3 bonding ratio increases which shows a nanostructure with less carbon sp3 bonding at defect sites. By exploring the chemical composition, the nitrogen content of the soot surface increases with NH3 addition which is caused by the bonding of nitrogenated species with carbon at defect and edge sites of the carbon layer, reducing the potential for carbon addition, and thus soot growth. The results also show an increased risk of formation of nitrogenated polyaromatic hydrocarbons (N-PAHs) on the soot surface by NH3 addition. The study presents a novel investigation of the impact of NH3 on the soot surface chemistry and particles nanostructure which explains the role of NH3 in suppressing soot growth and reveals the potential for new toxic characteristics for the soot emissions formed in NH3-hydrocarbon cofired systems.

Despite the extensive studies, accurate and reliable modeling of the soot inception process, especially at high pressure conditions, amenable to multi-dimensional flame simulations remains a challenge. In this study, the physical inception model was comprehensively evaluated in the fully-resolved simulations of laminar normal diffusion flame (NDF) and inverse diffusion flame (IDF) at elevated pressures. The effects of inception models on polycyclic aromatic hydrocarbons (PAHs) and soot predictions were quantitatively analyzed, including the selection of soot precursors and collision efficiency models. The results show that the quantitative PAH predicted by different collision efficiency models can differ by an order of magnitude. Compared to the constant efficiency, the temperature-dependent collision efficiency was found to improve the quantitative PAH predictions and the prediction of the spatial soot distribution in NDF, with an increased level of soot on the flame centerline. The inclusion of small-sized PAH species (such as A2, A2R5, and A3) as soot precursors was also found to improve the quantitative prediction of soot volume fraction. The physical inception model performs well in NDF using the optimal parameters. Moreover, simultaneous measurements of PAH and soot were performed in IDF configuration for the evaluation of the physical inception model. Contrary to NDF, PAHs and soot are formed on the outer side of the flame and cannot be oxidized in IDF. The experiment observed that the PAHs concentration increased in the post-flame region, while the soot concentration remained unchanged. However, the opposite trend was obtained in simulations, that is, the PAHs concentration decreased while the soot concentration increased, because the physical inception model predicts the inception behavior in the post-flame area, resulting in persistent transformation of PAHs into soot particles. To improve the predictions in IDF, the radical effects in the inception process need to be considered in the model.

The incipient sooting tendencies of oxygenated fuels in counterflow diffusion flames were systematically assessed by doping selected oxygenate fuels into the baseline fuel of ethylene with various mixing ratios. Laser light scattering and planar laser-induced fluorescence (PLIF) techniques were adopted. The critical oxygen mole fractions at different mixing ratios were identified with the use of laser scattering. It is found that the critical oxygen mole fraction varies with oxygenates, suggesting that the effect of mixing ethylene with oxygenates is highly sensitive to the types of oxygenate. While the doping of acetone moderately promoted the incipient sooting tendency, the doping of methanol, acetic acid, formic acid, and diethyl carbonate suppressed the formation of incipient soot. On the other hand, the doping of ethanol, dimethyl carbonate, diethyl ether, and dimethoxymethane had weak influences on the incipient sooting tendency. The production of polycyclic aromatic hydrocarbons (PAHs) of different sizes were measured by PLIF. The results show there was a strong correlation between the incipient sooting tendency and the production of large PAHs. One important finding is that, at their sooting limits, the total oxygen-to-carbon ratio of a stoichiometric fuel/oxygen mixture is linearly correlated with the mixing ratio of the ethylene-oxygenate mixture. This slope of these two quantities can be defined as an incipient sooting index (ISI) of oxygenated fuels for ranking their tendency of incipient sooting formation. Having the slopes correlated well with the oxygenates' hydrogen/oxygen ratio, a reasonably accurate prediction of critical oxygen mole fractions from the molecule information of oxygenated fuels can be achieved.

The temperature sensitivity of n-propylbenzene and 1,2,4-trimethylbenzene on soot formation in coflow diffusion flames was assessed. Cases with air temperatures at 300K (LT), 473K (MT), and 673K (HT) were established. Soot volume fractions and primary particle diameters were measured by Laser-induced incandescence. Soot temperatures were measured by rapid thermocouple insertion with correction by backward extrapolation. Soot yield also increased with temperature. Compared to alkanes and alkenes, alkylbenzenes exhibited much lower temperature sensitivity. The model suggested that elevating the reactant temperature did not significantly affect the production of soot precursor PAH in alkylbenzene flames, but altered the buoyancy-induced acceleration, which subsequently determined the time available for soot growth. Soot formation was promoted by extending the available time. To isolate the impact of fuel temperature, a case with heated fuel and unheated air (FHT) was also assessed. It is found that raising the fuel temperature affected soot formation more along the centerline than on the wing. This is suggested to be related to the earlier soot inception for FHT along the centerline.

Catalyst degradation due to soot formation is one of the main issues in the autothermal reforming (ATR) process, which is widely regarded as the future technology for hydrogen production from natural gas. In this work, soot formation under conditions similar to ATR was systematically investigated, focusing specifically on the effects of pressure on soot formation in inverse diffusion flames (IDFs) under oxygen rich conditions. Methane was diluted with carbon dioxide; the oxygen content in the oxidizer stream varied from 55 to 70%-by-mol. Polycyclic aromatic hydrocarbon (PAH) and soot concentrations in the flames were measured by laser-induced fluorescence (LIF) and laser-induced incandescence (LII) respectively. Flame images showed that, as the pressure increased, the luminous region of the IDFs moved downward to mask the blue reaction region, and the flames became narrower. The degree of flame narrowing in the IDFs was milder than normal diffusion flames (NDFs). LIF measurements showed that increasing the pressure promoted PAH formation, which also subsequently promoted soot formation. Both PAH and soot formation increased linearly with pressure. The linear relationship was different from that of the NDFs. Flame simulations suggested that the promotion of soot formation with pressure was largely driven by PAH adsorption. Under the conditions of this study, lowering the oxygen content promotes soot formation in the IDFs. The results of this work contribute to the understanding of soot formation in IDFs at elevated pressures and the optimization of the ATR process.

In the last two decades several mechanisms have been proposed for the growth of PAHs during combustion. Studies have suggested that the growth of PAHs of different structures should be analyzed carefully to improve our understanding of PAH formation during combustion. In this study, a wide of range of PAHs of different structures have been measured along the centreline of a coflow diffusion flame of ethylene using GC/MS, allowing for a previously not possible detailed analysis of potential formation routes. The discussed potential global empirical pathways can help in the development of accurate and detailed chemical mechanisms in the future. The experimental results show that the difference in reactivity of the sites of a PAH where growth takes place limits the formation of benzenoid PAHs at high temperatures. This difference in reactivity also leads to the formation of PAHs with a five-membered ring at high temperatures. The recombination of PAH radicals may not be favoured in this flame which explains the small amounts of alkyl-bridged PAHs at high temperatures. PAHs with an alkyl sidechain are favoured only along the free edge. Alkyl substituted PAHs are formed in low amounts and decrease with an increase in temperature. Methylene-bridged PAHs can lead to faster growth of large PAHs and become significant at intermediate temperatures. The target flame has also been simulated using state-of-the-art models. The simultaneous measurements of both PAHs and soot allowed for a comprehensive assessment of the chemical mechanisms and soot aerosol dynamics. The assessment suggests that both the chemical mechanisms and the soot aerosol dynamics need further improvements. The results confirm the importance of accounting for PAH structure when developing kinetic mechanisms and their coupled soot formation models. A complete database comprising of PAHs, soot and temperature is generated for future model validations.

Over the last 50 years, several chemical mechanisms have been proposed to understand the chemistry involved in the formation of Polycyclic Aromatic Hydrocarbons (PAHs) during combustion. These mechanisms range from sequential addition of small hydrocarbon intermediates to recombination of large aromatic radicals. Flames present a multitude of complexities due to high temperature gradients, short residence time and overlapping of several chemical reactions. Detailed chemical mechanisms have been developed to unravel the complex chemical pathways involved in a flame. Although these chemical mechanisms can explain the formation of PAHs from an aliphatic fuel (n-dodecane), it fails in case of an alkylated aromatic (1,2,4-trimethylbenzene). Alkylated aromatics represent a significant portion of practical fuels. An accurate prediction for these fuels is necessary to understand the practical combustion process. This study focuses on addressing how the chemical pathways of PAH formation from 1,2,4-trimethylbenzene differs from n-dodecane. The results show that 1,2,4-trimethylbenzene decomposition involves four dominant pathways of PAH formation: recombination of fuel molecule, PAH radical recombination, Clustering of Hydrocarbons by Radical Chain Reactions (CHRCR) and hydrogenation followed by methylation. The implications of these pathways on soot growth have also been discussed. A complete dataset comprising of PAH, soot and temperature measurements have been generated for 1,2,4-trimethylbenzene and n-dodecane for future model validations.

The effects of elevated reactant temperatures on soot formation in a laminar coflow ethylene flame were experimentally and numerically investigated. Ethylene flames at the reference reactant temperatures (both air and fuel), Tr, of 300K (LT), 473K (MT), 673K (HT), and 713K (UHT) were established. In the experiment, soot volume fractions (fv), primary particle diameters (dp), and soot (flame) temperatures (TF) were measured. The flames were also simulated by the CoFlame code with the Conjugate Heat Transfer (CHT) condition. The experimental results show that elevating Tr positively affects soot formation. The increase in the maximum fv is greater on the wing pathline (∼1.9 times) than on the centerline (∼1.2 times) when the adiabatic flame temperature increases by ∼100K. An analysis of the experimental and numerical data suggests that soot formation is promoted by enhanced soot surface growth. The numerical simulation reveals that PAH (polycyclic aromatic hydrocarbon) adsorption, which is a function of PAH concentration, becomes important at high Tr as its mass contribution increases from ∼50% to ∼70%. This may be attributed to early fuel pyrolysis within the fuel tube.

The relationship between soot surface growth, soot nanostructure and reactant temperature (Tr) in a coflow diffusion ethylene flame was investigated with multiple experimental techniques. The Tr was raised by heating the coflow air. Three cases, with 300K, 473K, and 673K Tr, respectively, were studied. Laser-induced Incandescence revealed that increasing Tr promotes soot formation. Although soot primary particle diameter (dp) also increases with Tr, the increase in dp slows down after 473K Tr, suggesting that there is a deceleration in soot surface growth. Transmission Electron Microscopy (TEM) imaging showed that increased Tr promotes soot aggregation and yields larger and more mature primary particles. The assessment of the Selected Area Electron Diffraction (SAED) patterns indicated that, at 673K Tr, there is a growth of lattice planes. Raman spectroscopy revealed further structural details. By assessing the band intensity ratios, soot for the Tr of 673K has more curved nanostructures. The deceleration of soot surface growth may be explained by surface aging, which is characterized by an increase in curved nanostructures.

Dimethyl ether (DME) is an alternative fuel with significantly reduced particulate (i.e., soot) emissions. The polycyclic aromatic hydrocarbons (PAHs) and soot formation in pure DME flames have not been fully investigated and there is a need to develop a detailed understanding of soot formation from pure DME without the confounding effect of other more sooting hydrocarbons. Therefore, PAH and soot formation in a pure DME /air laminar coflow diffusion flame were explored in this study for two different initial temperatures of the fuel. Gas chromatography /mass spectroscopy (GC/MS), and time-resolved laser-induced incandescence (TiRe-LII) were used to quantitatively measure PAH concentrations, soot volume fractions and primary particle diameters. The experimental results show that, before the appearance of the soot particles, the gas phase reactions are dominated by PAHs smaller than three rings (A3: phenanthrene and anthracene), which decrease along the centerline as the soot volume fractions increase. The primary particle diameters remain relatively constant along the radial profiles at different flame heights, which suggests a moderate surface growth. The numerical predictions of soot and PAHs (smaller than A3) formation are consistent with the measurements (within a factor of 2.4), while the overprediction of the mole fraction of A3 is near an order of magnitude. The model can also capture the effect of increasing the initial fuel temperatures with reasonable accuracy. The experimental results suggest that PAHs are mainly formed by Hydrogen Abstraction Carbon (Acetylene) Addition (HACA), C1 addition is efficient for monoaromatic while the addition of C3 and species containing cyclopentadienyl moiety are not dominant for PAH growth. A database of the PAHs and soot formation has been created for further investigation of this DME flame.