Soot Measurements Research Articles

Online Raman spectroscopy for quantitative detection and characterization of aerosolized soot

Ex-situ Raman spectroscopy is a well-established method for the structural characterization of soot but necessitates a sampling step before analysis is made. This work studied the potential to perform Raman spectroscopic measurements of soot directly in the combustion exhaust gases, i.e., online Raman measurements. Two types of soot were produced from a Mini-CAST soot generator, one immature with high organic content and one mature with low organic content. Also, two different measurement configurations were used, a 90-degree and a backscattering configuration, as well as different polarization combinations of the laser radiation and the detected photons. Spectrally resolved Raman signals were successfully recorded and analyzed for the two soot types showing differences between the characteristic D and G peaks as well as the photoluminescence signal. Additionally, the Raman cross section was determined for both soot types and found to be higher for the immature soot. It was also found that a horizontally polarized laser excitation and a 90-degree collection angle had the best potential to reduce the interference from ambient gases. This study can be seen as a first step towards remote sensing of soot.

Effect of 2-butanone addition to ethylene fuel on soot formation in counterflow diffusion flames using newly proposed soot model

An improved consistent soot model is proposed and applied to evaluate the effect of 2-butanone addition (10 % to 50 % on a volume basis represented as case 1 to case 5) to ethylene fuel on soot formation using a counterflow burner configuration. The predictive capability of the suggested soot model is verified by assessing its performance against existing experimental data on soot formation (SF) configuration-type ethylene counterflow flames at diverse strain rates and various fuel additives. The proposed soot model comprises 55 inception reactions with temperature-dependent collision efficiency and 10 condensation reactions from 10 PAH species (from naphthalene to larger PAHs up to coronene), including modified HACA surface growth and oxidation reactions. 2-butanone is produced as a byproduct during the pyrolysis of biomass and the microbiological fermentation of agricultural waste. It holds various benefits as a prospective biofuel for spark ignition (SI) engines. Limited information exists regarding its sooting characteristics due to a lack of available soot measurements. The simulations are conducted for the soot formation (SF) type counterflow flames with a fixed fuel and oxidizer jet velocity. The proposed soot model can effectively replicate both the qualitative and quantitative aspects of the experimental trends and shows a better agreement than the existing models available in the literature. The soot volume fraction (SVF) and the particle number density (PND) decrease with increasing the 2-butanone concentration in the binary fuel mixture. The PAH concentration decreases with increasing 2-butanone addition in the fuel mixture. The peak SVF and the maximum temperature are reduced by ∼22.7 % and ∼3.6 %, with a 40 % increase in the 2-butanone portion in the fuel mixture from case 1 to case 5. Increasing the 2-butanone content in the fuel mixture decreases the inception rate, HACA rate, and condensation rate while it increases the oxidation rate.

Oxidation dynamics of soot or carbon black accounting for its core-shell structure and pore network

Internal oxidation is most important for removal of soot in diesel particulate filters. Furthermore, it enhances the porosity of carbon blacks (CBs), increases their specific surface area, SSA, determining their performance in batteries, inks and tires, as well as their environmental and health impact. Current models for oxidation of soot or CB neglect its fractal-like pore network during internal oxidation and underestimate its SSA by 60 % on average! Here, a lattice Monte Carlo (LMC) model elucidates both external and internal oxidation dynamics of soot (or CB) accounting for its fractal-like pore structure, for the first time to the best of our knowledge. Random internal oxidation takes place at the bulk soot (or CB), expanding its pore network and increasing the pore fractal dimension, Dfp, up to 3, in good agreement with data. This increases the SSA up to a factor of ten at 75 % conversion. In the presence of a less reactive shell though, internal oxidation stops after the reactive core is consumed. Thus the SSA levels off at large conversions (>50 %). Hence, accounting for the realistic core-shell, fractal-like pore structure during simultaneous external and internal oxidation nicely explains several measurements of soot and CB Dfp, SSA and particle diameter. So the LMC-derived oxidation dynamics of soot or CB presented here can be used to assist the design of highly porous CB grades from first principles, as well as the mitigation of soot emissions by enhancing their oxidation.

A 3D computational study of the formation, growth and oxidation of soot particles in an optically accessible direct-injection spark-ignition engine using quadrature-based methods of moments

The accurate prediction and assessment of soot emissions in internal combustion engines play a central role in the development of modern, sustainable powertrains. The modeling of soot requires high-fidelity models capturing both the gaseous soot precursors with suitable mechanisms and an accurate description of all physico-chemical processes related to the solid particulate. Semi-empirical models based on acetylene are frequently used but are limited in covering complex fuel compositions.For this reason, we present the coupling of a detailed quadrature-based method of moments (QMOM) soot model to a state-of-the-art flow solver for the simulation of gasoline engines. A close coupling with the underlying gas phase and the additional consideration of polycyclic aromatic hydrocarbons (PAHs) as precursors allow an accurate description of the entire cause-and-effect chain. The fully coupled model is then applied in a 3D-CFD simulation of an optically accessible research engine to investigate the formation, growth and oxidation of soot particles. Experimental high-speed measurements of soot- luminescence and extinction were used for validation purposes. Together with all preceding models along the engine cycle, the newly implemented model is used to identify the root cause of the observed soot formation hotspots. Particular emphasis is placed on the effects of soot oxidation.

Study on the application of laser diagnosis technology in the rapid real time measurement of soot

Based on previous soot studies, this paper proposes a new method to quantify the evolution of the soot generation mechanism in flames. The soot distribution in inverse diffusion flame at different fuel gas velocities was quantitatively measured by laser-induced incandescent (LII) technique, and the soot structure evolution was analyzed by Raman spectroscopy and field emission transmission electron microscopy (FETEM). Laser-induced breakdown spectroscopy (LIBS) and numerical simulation were used to investigate the association between the intensity ratio of hydrocarbon atoms of at different positions of the flame and soot formation. Meanwhile, a detailed chemical kinetic simulation of the formation process of soot was carried out, and the flame structure was divided in more detail. The flame state in different regions and the key reactions of soot formation were analyzed. The results presented that the volume fraction of soot measured by LII is consistent with the height-dependent graphitization of the flame and is identical to the yellow definition of the flame. The variation of the C/H atomic intensity ratio reflected the soot formation in flame. The CH intensity ratio in the flame axial direction showed a bimodal distribution, corresponding to the blue phase of soot precursor formation and the yellow phase of soot formation, respectively. In addition, the CH atomic intensity ratio and the CH atomic molar ratio showed a parabolic transition from incipient to mature soot in the soot production region. The CH intensity ratios at different heights are linear in the radial direction, and the main core region of soot production can be obtained when the CH intensity ratio is 0.10 ∼ –0.13. With radial distance increases, it is clear results that the most sensitive reaction of (precursor) A1 changes from C6H5OH + H = A1 + OH to C2H3 + HCO=C3H3 + OH. It reveals that with the increase of yellow light, the soot structure along the flame center line is gradually graphitized, and the graphitization degree is the highest at the axial height of 18.0De ∼ 22.4De. This is consistent with the distribution of CH atomic intensity ratio. The present results demonstrate that LIBS can quickly achieve the initial measurement of soot and provide a new method for the study of flame soot during its evolution.

Measurement of Soot Generated by Biodiesels Using Laser-Induced Incandescence Method

Measurement of Soot Generated by Biodiesels Using Laser-Induced Incandescence Method

Temperature, soot, and OH*/CH* chemiluminescence measurements of partially-premixed CO2-diluted propane flames on a linear Hencken burner

Recent studies highlight the need for further examination of partially-premixed diffusion flames with applications in modern burner configurations that increasingly rely on technologies such as flue gas recirculation and oxy-fuel combustion, which increase the CO 2 content in the combustion environment. The partially-premixed nature of the linear Hencken burner (LHB) offers a unique platform with many advantages over comparable slot-type or radially-symmetric burner configurations. In this work, partially-premixed laminar propane flames were examined under increasing CO 2 percentages (0 to 50% v ). Prosumer grade digital CMOS cameras were calibrated and used to determine two-dimensional, quantitative measurements of soot, temperature, and OH* and CH* chemiluminescence. Soot values were additionally supported via laser extinction measurements using a 532 nm continuous wavelength laser. The peak soot volume fraction was found to decrease from 318 ppbv for the pure propane case down to 37 ppbv for the 50% v CO 2 case, while the corresponding temperature decreased from 1876 K down to 1742 K. The data also suggested that soot maturity decreased in conjunction with overall concentration. The regions of peak OH* and CH* concentrations maintained their transverse positions as well as their relative positions with respect to one another for all flame conditions, though moved axial further away from the flame base with increasing CO 2 . Additionally, the peak OH* region remained closer to the central flame axis across all conditions, a result that is counter to other studies that examined CO 2 dilution in purely non-premixed flames. • 2D quantitative soot and temperature measurements of CO2 diluted partially-premixed propane flames. • Laser extinction measurements bolster 2D soot values. • Fuel dilution over 40%v CO2 starts to significantly lower soot maturity. • 2D quantitative chemiluminescence measurements of OH* and CH* in CO2 diluted partially-premixed propane flame. • Movement of peak chemiluminescent regions show significant differences versus premixed and dilution flames.

Transported JPDF modelling and measurements of soot at elevated pressures

Accurate measurements and modelling of soot formation in turbulent flames at elevated pressures form a crucial step towards design methods that can support the development of practical combustion devices. A mass and number density preserving sectional model is here combined with a transported joint-scalar probability density function (JDPF) method that enables a fully coupled scalar space of soot, gas-phase species and enthalpy. The approach is extended to the KAUST turbulent non-premixed ethylene-nitrogen flames at pressures from 1 to 5 bar via an updated global bimolecular (second order) nucleation step from acetylene to pyrene. The latter accounts for pressure-induced density effects with the rate fitted using comparisons with full detailed chemistry up to 20 bar pressure and with experimental data from a WSR/PFR configuration and laminar premixed flames. Soot surface growth is treated via a PAH analogy and soot oxidation is considered via O, OH and O2 using a Hertz-Knudsen approach. The impact of differential diffusion between soot and gas-phase particles is included by a gradual decline of diffusivity among soot sections. Comparisons with normalised experimental OH-PLIF and PAH-PLIF signals suggest good predictions of the evolution of the flame structure. Good agreement was also found for predicted soot volume statistics at all pressures. The importance of differential diffusion between soot and gas-phase species intensifies with pressure with the impact on PSDs more evident for larger particles which tend to be transported towards the fuel rich centreline leading to reduced soot oxidation.

Assessment of physical soot inception model in normal and inverse laminar diffusion flames

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.

Soot-free and low-NO combustion of Jet A-1 in a lean azimuthal flame (LEAF) combustor with hydrogen injection

The quest for aeroengine technologies capable of reducing soot and NOx emissions motivates the development of novel burner concepts. The present work contributes to this line of research by presenting and characterizing a low emissions LEAF combustor fuelled with Jet A-1 and hydrogen at atmospheric condition. The inclined air injection from the top manifold creates an azimuthal flow entraining the Jet A-1 sprays from the bottom manifold and produces, under favorable conditions, a toroidal distributed reaction zone which we call LEAF. In this LEAF, the combustion of the fuel from one atomizer provides a vitiated environment to the spray of the next atomizer. The flame topology and spray characteristics are analysed by means of OH* and CH* chemiluminescence, Mie scattering and soot luminescence. The burner is operated at a constant equivalence ratio with varying thermal power and air-to-liquid massflow ratio (ALR) of the air-blast atomizers. The flame topology is significantly influenced by the atomization air, through its simultaneous effect on the spray characteristics and the flow field. At low atomization air mass flow rates, the combination of lower mixing and larger spray Sauter Mean Diameter (SMD) results in localized droplet and non-uniform spray combustion. Consequently, these inhomogeneities in the combustion process prevent the formation of a LEAF and lead to topological transition of the flame to a tubular shape. In this study, we show that by injecting hydrogen into the combustor we can stabilise a LEAF topology at low ALR. At higher ALR, smaller spray SMD and higher mixing results in a spread-out reaction of hot oxidisers and evaporated fuel, which are characteristics of flameless oxidation. Measurements of soot and NO at the combustor exhaust show very low emission of NO and unburnt fuel and no soot emission, even in absence of preheating of the combustor air.

PM2.5, and soot measurements in Gqeberha municipality, South Africa

Background and aim: Air pollution is a major risk factor in Africa. Air pollution exposure assessment studies are lacking in South Africa and Africa, especially on fine particulate matter (PM2.5) and its chemical composition. The aim of this study was to assess the PM2.5 and soot levels in Gqeberha municipality, Eastern Cape province, South Africa Method: The study was conducted in an urban area located in Gqeberha municipality. Gravimetric analysis was used to determine PM2.5 levels from May 2021 to January 2022. Soot measurements were done using a smoke stain reflectometer. All analysis was done in the air quality laboratory at the School of Health Systems and Public Health (SHSPH) at the University of Pretoria. Results: The average PM2.5 level during the study period was 4.97± 2.99 µg/m3 which was lower than the annual WHO air quality guideline (5 µg/m3) and lower than the annual South African air quality standard (20 µg/m3). The mean soot level was 1.07 10-7m-1. Conclusion: This baseline study shows that background level PM2.5 levels in Gqeberha municipality. Although these levels are relatively low, further studies in the area are still needed. Especially that evidence shows that low levels of PM2.5 can lead to adverse health effects. Keywords: Air pollution, PM2.5, South Africa, black carbon, soot

Measurements of soot and response optimisation of laminar pool and prevaporised jet flames for various oxygenated biofuels

In this study, the generation of soot from the combustion of biodiesels and their blend with fossil diesel are investigated under laminar pool flame and prevaporised diffusion jet flame conditions. Neat biodiesels from eight feedstocks including carotene palm, palm, soy, coconut, rice bran, waste vegetable oil, duck, and goose, alongside two methyl esters of methyl laureate and methyl myristate are blended with fossil diesel at 20% volumetric intervals to form 51 different blends. The soot volume fractions for the combustion of all blends are determined using continuous-wave laser cavity extinction (CW-LCE) calibrated 2D laser-induced incandescence (2D-LII) technique. Results show that biodiesels with higher degree of saturation produce less soot, as reflected in both laminar pool and prevaroprised diffusion jet flames. The experimental data is further analysed using design of experiments (DOE) methodology. The mixture design model (MDM) following the simplex design is used to focus on the soot generating effects arising from the chemical compositions by classifying the chemical components into hydrocarbons and saturated, monounsaturated and polyunsaturated fatty acid methyl esters (FAME). The results from the Cox response trace plot associated with DOE elucidate the effects of the individual chemical group within the fuels. Both laminar flame types for the all 51 biodiesel-diesel blends exhibit the same trends with differing magnitudes. Saturated FAME has the largest singular effect on soot generation followed by hydrocarbons. However, when only neat biodiesels are considered, the laminar pool flame and laminar diffusion jet flames show differing trends for all the chemical groups. Monounsaturated FAME and saturated FAME have the greatest influence on neat biodiesel-generated soot for laminar pool flame and laminar diffusion jet flame, respectively. From the mixture design model, an optimum synthetic biodiesel mixture containing 16.1%, 34.6% and 49.3% of saturated, monounsaturated and polyunsaturated methyl esters is recommended for the lowest soot generation.

A new thermodeactivation model for soot surface reactivity toward O2 in turbulent hydrocarbon diffusion flames

ABSTRACT Accurate soot modeling in flames is one important tool contributing to an understanding of soot behavior in combustion. Soot models reflect the four principal processes that govern soot dynamics: nucleation, coagulation, surface growth, and oxidation. Existing oxidation models reflect both the temperature-dependent surface oxidation chemical kinetics and also the fact that the surfaces become less reactive as they age. This surface deactivation process has been modeled primarily by using in-flame soot measurements as a basis for developing functional forms and parameters to describe the decay of α, the ratio of active oxidation sites divided by total surface sites. These existing models, in general, overpredict oxidation rates in turbulent diffusion flames. This study presents an alternative soot aging factor model that is based on the analogous process of coal char oxidation deactivation, a well-studied problem. The proposed framework provides a basis for application to a wide range of turbulent diffusion flames. This new model is configured to provide the same parameter α that appears in existing approaches. As such it can be easily applied to the existing published models. The approach is implemented in the fixed-pivot sectional soot model, with the performance compared against literature data for ethylene/air turbulent diffusion flames. With only very minor adjustment from the baseline parameters developed for coal char, the model shows good agreement with the literature flame data.

Slight asymmetry induces significant distortion of soot volume fraction measurements in counterflow diffusion flames with diffuse back-illumination imaging.

Counterflow diffusion flame is a favorable platform for fundamental investigation of soot kinetics. A diffuse back-illumination imaging technique for measuring soot volume fractions in these flames was rigorously demonstrated here. It was noticed that the technique is extremely sensitive to slight asymmetry of the flame. Misleading conclusions could be drawn due to the surprisingly large distortion of the measured SVF profile caused by flame tilting, even when the tilting is so slight as to be undetectable through the flame images. To address this issue, the effect of the flame tilting on soot measurements were quantitatively analyzed and a novel procedure was proposed to identify and correct the measurement distortions.

Angle Scattering Method for Soot Concentration Measurement under Ultra-Low Emissions Condition

Aiming at the problem of soot concentration measurement under ultra-low emission conditions, a forward small angle soot concentration measurement method is proposed. Taking a typical boiler emission of 0.1 μm–3.0 μm bimodal distribution soot as an object, the particle scatter simulation calculation under different parameters is carried out, and the influence of detection angle and particle size on the angular scattering measurement of ultra-low emission soot is analyzed. The influence of detection angle and particle size on the angular scattering measurement of ultra-low emission soot is analyzed. Preferably, the wavelength of incident light is 650 nm, and the forward detection angle parameter is 15° for the design of forward small angle soot concentration measurement system. An experimental system for measuring soot with standard concentration is built. Experiments of particle concentration measurement of 1.0 μm and 3.0 μm under ultra-low emission conditions are carried out. The results show that the average deviation of soot concentration measurement is less than 0.10 mg/m3 under the condition of ultra-low emission by using 15° of forward detection, which provides an effective way for monitoring ultra-low emission soot concentration in coal-fired power plants.

Experimental Investigation on the Performance and Emission Characteristics of a Compression Ignition Engine Using Waste-Based Tire Pyrolysis Fuel and Diesel Fuel Blends

Due to the world’s growing population, the size of areas intended for food production in many countries of the world can only be achieved through severe environmental damage and deforestation, which has many other detrimental consequences in addition to accelerating global warming. By replacing the bio-content of fuels with other alternative fuels, land that is used for energy crops can also be used to grow food, thus mitigating the damaging effects of deforestation. Waste-based tire pyrolysis oil (TPO) can be a promising solution to replace the bio-proportion of diesel fuel. Since it is made from waste tires, it is also an optimal solution for recycling waste. This research shows the effect of different low-volume-percent tire pyrolyzed oil blended with diesel on the performance, fuel consumption, and emissions on a Mitsubishi S4S-DT industrial diesel engine. Four different premixed ratios of TPO were investigated (2.5%, 5%, 7.5% and 10%) as well as pyrolysis oil and 100% diesel oil; however, the following studies will only include the data from the pure diesel and the 10% TPO measurements. The experimental investigations were in an AVL electric dynamometer, the soot measurements were in an AVL (Anstalt für Verbrennungskraftmaschinen List) Micro soot sensor (MSS), and the emission measurements were in a AVL Furier-transform infrared spectroscopy (FTIR) taken. The scope of research was to investigate the effect of low volume percentage TPO on performance and emissions on a light-duty diesel engine.

Watching soot inception via online Raman spectroscopy

In this work, online spontaneous Raman spectroscopy was applied to study the soot inception and growth zones of a low pressure premixed ethylene/oxygen flame. Firstly, we measured online Raman spectrum of aerosol soot extracted from the flame. The spectrum was compared to ex situ Raman measurements of the same soot after being deposited on a window. In the aerosol soot particles, the presence of an abundant sp hybridized carbon chain component is inferred accompanying a polycyclic aromatic component. Both cumulenic and polyynic chains are affected by the deposition under vacuum and by the pressure as it is raised to atmospheric, revealing that the sp phase is no longer visible in the ex situ characterization of the sampled soot. Secondly, we monitored the Raman spectra of aerosol soot as a function of the height above the burner. Comparing spectral differences of by-products along the blue to orange zone of the flame permitted the soot formation and evolution to be probed. The online spectra, by avoiding structural modifications of the real soot structures by deposition, highlight the role of unsaturated carbon chains in the chemical condensation scenario.

Experimental and Numerical Study on the Sooting Behaviors of Furanic Biofuels in Laminar Counterflow Diffusion Flames

Furanic biofuels have received increasing research interest over recent years, due to their potential in reducing greenhouse gas emissions and mitigating the production of harmful pollutants. Nevertheless, the heterocyclic structure in furans make them readily to produce soot, which requires an in-depth understanding. In this study, the sooting characteristic of several typical furanic biofuels, i.e., furan, 2-methylfuran (MF), and 2,5-dimethylfuran (DMF), were investigated in laminar counterflow flames. Combined laser-based soot measurements with numerical analysis were performed. Special focus was put on understanding how the fuel structure of furans could affect soot formation. The results show that furan has the lowest soot volume fraction, followed by DMF, while MF has the largest value. Kinetic analyses revealed that the decomposition of MF produces high amounts of C3 species, which are efficient benzene precursors. This may be the reason for the enhanced formation of polycyclic aromatic hydrocarbons (PAHs) and soot in MF flames, as compared to DMF and furan flames. The major objectives of this work are to: (1) understand the sooting behavior of furanic fuels in counterflow flames, (2) elucidate the fuel structure effects of furans on soot formation, and (3) provide database of quantitative soot concentration for model validation and refinements.

Chemical speciation and soot measurements in laminar counterflow diffusion flames of ethylene and ammonia mixtures

Ammonia is considered as one of the most promising alternative fuels due to its carbon neutrality and the existing infrastructure for its mass production and delivery. However, burning neat ammonia has the issue of poor flame stability and high NOx emissions, making co-firing ammonia with conventional fuel a more feasible approach. The present work investigated the sooting characteristics of counterflow diffusion flames of ethylene/ammonia mixtures. Experimentally, soot volume fraction (SVF) and average soot particle diameter in the neat ethylene, ammonia- and nitrogen- doped flames were non-intrusively measured. Both SVF and average soot particles diameter were found to decrease with the addition of ammonia. Flame temperature were measured with tunable diode laser absorption spectroscopy and the results suggested that the inhibiting effect of ammonia on soot formation was chemical instead of thermal. For further kinetic insights, numerical simulation with newly-constructed reaction mechanisms were performed and the results were compared against chemical speciation data from gas chromatography (GC) measurements; the results showed that ammonia doping would lead to more significant reduction of benzene concentration than nitrogen doping. Kinetic pathways of the chemical suppressing effect of ammonia addition on soot and its precursor formation were then explained based on numerical results. The major contribution of the present work can be summarized in the following aspects: 1) New comprehensive experimental data on sooting characteristics, important intermediate species concentrations of diffusion counterflow flames of ethylene/ammonia mixtures were provided for model validation; 2) One coupled mechanism with detailed hydrocarbon-nitrogen interactions was established to predict PAHs formation and soot formation; 3) Detailed chemical kinetics insight of ammonia effect on soot formation was presented in the counterflow flame.

A calibration-free two-dimensional spectral soot emission platform for temperature and soot measurements

A simple and cost-effective temperature and soot volume fraction measurement technique that does not rely on spectral or absolute irradiance calibration is developed. The technique is based on a three-sensor CMOS camera, where the broadband sensitivity of RGB sensors were narrowed down to representative wavelengths using a tri-bandpass filter. A telecentric imaging lens was used to improve the accuracy of the tomographic deconvolution of the axisymmetrical ethylene laminar diffusion flames stabilized on a co-flow burner. Temperature and soot concentration measurements have been compared with results previously reported from the same burner. Good agreement for temperature measurements and excellent agreement for soot concentration measurements have been shown. Additionally, to demonstrate the dynamic range of the system, two-dimensional temperature and soot volume fraction fields were measured for four cases of dilution corresponding to various soot loadings. As the dilution rate was increased, the peak soot volume fraction was drastically reduced and temperatures were increased in accordance with the reduced dissipative heat losses from broadband soot radiation.