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January 1991 - December 2012
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- Soot formation
Publications
Publications (207)
The present work expands previous studies on the kinetics of the n-C 3 H 7 I unimolecular decomposition and the thermodynamic properties of n-C 3 H 7 I and i-C 3 H 7 I molecules, by providing combined experimental and theoretical data on the rate constant for reaction of n-C 3 H 7 I + Ar ⇌ n-C 3 H 7 + I + Ar, as well as thermodynamic data for iodop...
This work presents new information on the interaction of a promising biofuel - furan and the products of its decomposition with molecular oxygen under conditions simulating combustion processes. The investigations were carried out using the precision method of atomic resonance absorption spectroscopy on a high-purity shock tube behind reflected sho...
The ignition and combustion of three-component methane–hydrogen biofuel mixtures, considered as prospective fuels, were experimentally and numerically studied. Ignition delays in argon-diluted methane–hydrogen mixtures partially substituted with methanol or dimethyl ether were measured behind reflected shock waves in a temperature range of 1050–190...
Currently, substances are being actively sought that could serve as the alternative fuel or fuel additive reducing formation and emission of the carbon nanoparticles. Here, processes of the polyaromatic hydrocarbons (precursors of the carbon condensed phase formation) and carbon black nanoparticles formation during the ethylene pyrolysis with addit...
The formation of atomic oxygen in high-temperature gas flows affects both the thermodynamic state of the gas and the kinetics of proceeding chemical processes. During hypersonic and space flights, there is still a significant lack of understanding of the phenomena of flow around high-speed vehicles. One of the main reactions occurring in the bow sh...
The problems of improving the safety of various industrial facilities dealing with combustible mixtures are constantly in the center of increased attention. The introduction of chemically active additives into the gas mixture is considered as one of the most effective ways to prevent ignition and explosion. One of the most promising highly effectiv...
In this article, we experimentally studied the effect of acetone impurities on the induction time and soot yield during the self-decomposition of acetylene behind shock waves. The results of the experiments showed that variation of the acetone impurity in the range 0.5–3.0%, characteristic of technical acetylene, does not have a significant effect...
This paper presents the experimental and calculated results of the investigation of soot formation in a standard premixed ethylene/air flame with the addition of 15–100% dimethyl ether. The soot volume fraction was measured using the laser light extinction method at a wavelength of 520 nm. The flame temperature versus height above the burner was me...
The influence of various oxygenated co-reactants on soot formation was addressed by studying the pyrolysis of gas mixtures using ethylene as a base fuel in the absence of molecular oxygen. Alcohols (methanol, ethanol, and n-butanol) and ethers (diethyl ether, dimethoxymethane, furan, and tetrahydrofuran) were selected as oxygenated co-reactants. Th...
High-temperature oxidation of acetylene (C2H2) is studied behind reflected shock waves and in laminar flames. Atomic resonance absorption spectroscopy (ARAS) is employed to record oxygen atom concentration profiles for the mixture of 10 ppm C2H2 + 10 ppm N2O + argon and temperatures from 1688 K to 3179 K, extending the range of such data available...
In this work, the kinetics of pyrolysis and subsequent soot yield in undiluted mixtures of acetylene with chemically active additives, namely acetone, hydrogen, oxygen, methane and propane–butane mixture, were investigated numerically over a wide range of pressures and temperatures using the modern kinetics mechanisms. It was shown that with differ...
In this paper, the dependence of the sublimation temperature of soot particles synthesized during the combustion of various hydrocarbons, depending on their size and structure, is obtained. The experimental approach is based on the analysis of the thermal radiation of particles heated to the sublimation temperature by a nanosecond laser pulse. The...
In this work the laser-induced fluorescence (LIF) method was used to study the formation of polyaromatic hydrocarbons (PAHs) in the pyrolysis of benzene C6H6 and dimethyl ether C2H6O (DME) mixtures diluted with argon behind reflected shock waves within a temperature range of 1300–2000 K and pressures of 3.5–5.7 bar. To monitor the volume fraction o...
The effect of various hydrocarbon additives, dissociating with methyl radical formation, on acetylene decomposition over the wide range of temperatures was studied. Methane, ethane, propane/butane mixture, dimethyl ether (DME), and diacetyl were considered. The experiments with acetylene doped with methane, DME, and diacetyl and diluted with argon...
The time profiles of nonequilibrium radiation of electronically excited state of carbon monoxide CO (a3Πr) formed in the oxidation of methane behind shock waves at high temperatures were registered for the first time. The experiments were carried out in mixtures of CH4 with N2O and O2 in argon at temperatures of 2200—4200~K and pressures of 240±40~...
Acetylene black is a special type of carbon black, obtained from the thermal decomposition of acetylene. Acetylene flames enable the investigation of the soot optical properties. A reliable knowledge of the optical properties of acetylene soot is necessary for interpreting the optical measurements in flames and the development of acetylene black ap...
McKenna burner providing premixed, laminar, steady flat flame is widely used in the combustion community. The ethylene/air flame with equivalent ratio of 2.34 is considered as one of the target flames for the development and calibration of optical diagnostics of soot particles. In this work, the accurate soot particle sizing in dependence on the he...
It is well known that the propagation of traditional combustion and detonation waves was determined by the branched chain reactions discovered by Academician N.N. Semenov. This article discusses a new type of detonation waves initiated by chemical condensation processes. Chemical condensation waves arise as a result of the heat released during the...
In a number of recent studies by the authors, a new physical phenomenon has been discovered and investigated in detail — the formation of a detonation wave during the condensation of highly supersaturated carbon vapor. The essence of the phenomenon is that an initiating shock wave propagating through an exothermic carbon compound (for example, carb...
This work provides, for the first time, new information regarding the kinetics interaction between N2O and propyl alcohol isomers. To this end, the formation and consumption of atomic oxygen were measured behind the reflected shock waves using Atomic Resonance Absorption Spectroscopy (ARAS) technique for 1–10 ppm n- i-propanol + 10 ppm N2O + Ar mix...
Acetylene is an exothermic hydrocarbon capable of self-decomposition and detonation without an oxidizing agent.
Modern comprehensive kinetic mechanisms for modeling the oxidation of hydrocarbon mixtures in the high-temperature range do not consider possible excited states of radicals and molecules that can affect combustion processes at certain time intervals.
Data on the optical properties of soot are necessary to calculate the amount of sunlight absorbed by nanoparticles in the atmosphere and on the surface of the ice. Such information is used for calculating the radiation heat exchange in combustion processes, assessing the quality of carbon black, and other applications. To date, a large amount of da...
An experimental study of the kinetics of oxidation of dimethyl ether, n-butanol, and methane was carried out using emission and atomic resonance absorption spectroscopy. All experiments were performed in a shock tube behind reflected shock wave in a wide temperature range from 1890 to 3250 K at a pressure of 2.4 ± 0.4 bar. In all investigated condi...
![The heat capacity of bulk graphite [50]](publication/342726879/figure/fig3/AS:960078718971938@1605912012933/The-heat-capacity-of-bulk-graphite-50_Q320.jpg)
It is crucial to understand the behavior of the optical properties of soot in the visible and near-IR spectral range to calculate the magnitude of their emission and absorption. Such information also helps in the development of diagnostic methods for soot. We measured the absolute value of the refractive index functions of soot nanoparticles E(m,10...
![Figure 2. The measured [1,27,28] (symbols) and calculated (curves)...](publication/342740887/figure/fig1/AS:910648821174272@1594127006024/The-measured-1-27-28-symbols-and-calculated-curves-temperature-dependences-of-the_Q320.jpg)
For the first time, the rate constant of the thermal monomolecular decomposition of n-C 3 F 7 I in Ar was measured directly using the technique of atomic resonance absorption spectroscopy on a resonant line of iodine atom. Experiments were conducted behind the incident and reflected shock waves in a broad range of thermodynamic parameters ( T = 800...
The kinetics of reaction of C2H5OH with N2O behind shock waves is studied. The quantitative measurements of the time profiles of concentration of O atoms were carried out by the method of atomic resonance absorption spectroscopy (ARAS) using resonance vacuum-ultraviolet line of O-atom at 130.5 nm. For the calibration of absorption intensity of oxyg...
Evaporation of iron nanoparticles in carbon shells under pulsed laser irradiation is analyzed. Iron–carbon nanoparticles are synthesized in a shock tube reactor with the aid of pyrolysis of the 0.25% Fe(CO)5 + 0.25% C6H6 mixture in argon. Laser radiation is used for additional heating to temperatures that exceed the evaporation threshold of the iro...
A strong difference in the character of admixture effect on ignition by shock wave and spark initiation has been revealed using the haloalkane effect on the ignition of methane–oxygen mixtures as an example. It has been shown that the difference is determined by the presence of considerable concentrations of reactive intermediate species in an init...
A strong difference in the character of admixture effect on ignition by shock wave and spark initiation has been revealed using the haloalkane effect on the ignition of methane–oxygen mixtures as an example. It has been shown that the difference is determined by the presence of considerable concentrations of reactive intermediate species in an init...
In this work, the iron nanoparticles were formed after the pulse UV laser photolysis of Fe(CO) 5 vapor in argon atmosphere. The second laser pulse was implemented for heating of formed iron nanoparticles at different times from the moment of its formation. The registration of incandescence signals from laser-heated nanoparticles allowed measuring t...
The nonequilibrium radiation occurring during ignition of a 10% stoichiometric hydrogen-oxygen mixture with flame suppressant additives diluted with argon behind shock waves was studied. Instead of the expected reduction in the super-equilibrium radiation of active radicals in the ignition zone, the addition of halogenated flame suppressants led to...
It was noted a significant increase in soot formation with the addition of methane in the pyrolysis of acetylene in shock tubes. Qualitative kinetic analysis revealed an increase of propargyl formation due to methyl/methylene and acetylene recombination. Here, we study the role of methyl radicals in the soot formation process more carefully. Mixtur...
This work presents the first direct experimental study on the thermal unimolecular decomposition of n‐C3F7I. Experiments were performed behind incident and reflected shock waves using the atomic resonance absorption spectroscopy (ARAS) technique on a resonant line of atomic iodine at 183.04 nm. The reaction C3F7I + Ar → C3F7 + I + Ar (1) was studie...
Experiments on the pyrolysis of C2H2/Ar and C6H6/Ar mixtures with addition of H2, O2, and CH4 have been carried out behind reflected shock waves at temperatures ranging from 1400 to 2600 K. Soot formation was measured by laser extinction at 633 nm. Time-resolved temperature measurements were performed via two-color CO absorption on the P(8) and R(2...
Time-resolved laser-induced incandescence for particle sizing and laser light extinction for soot volume fraction was applied simultaneously to study the influence of methane addition on soot formation in acetylene pyrolysis. Three series of the experiments with initial mixtures of 2% C2H2 + Ar, 1% CH4 + Ar and 2% C2H2 + 0.5/1/2% CH4 + Ar in the te...
In this work, the influence of additives of iodinated hydrocarbons trifluoroiodomethane (CF3I) and 1-iodoperfluoropropane (C3F7I) on shock-induced ignition of acetylene and methane was experimentally investigated. The observed temperature dependencies of induction times indicate that both suppressants show noticeable inhibiting activity in acetylen...
The growth of carbon particles was studied in heated flows of a burnt-gas flow reactor containing mixtures of N2/C2H2, and N2/C2H2 with addition of H2 or CH4 surrounded by a rich C2H4/air flame. Soot particle sizes and volume fractions were measured by laser-induced incandescence (LII) between 50 and 130 mm above the nozzle exit. The measurements i...
The kinetics of the dissociation of CF3I behind shock waves was experimentally investigated. The reaction CF3I + Ar → CF3 + I + Ar was studied at temperatures between 900 and 1250 K and pressures of 2-3 bar. For this purpose, the time profiles of the concentration of atomic iodine were measured using a highly sensitive atomic resonance absorption s...
Carbon-encapsulated molybdenum nanoparticles were synthesized by laser-assisted photolysis of gaseous precursors. In the proposed method, gas mixtures containing various hydrocarbons and molybdenum hexacarbonyl vapor diluted in argon were irradiated with a nanosecond pulsed UV laser at room temperature. Particle samples were analyzed by transmissio...
This work is devoted to the investigation of combustion of simple and complex gaseous fuels: methane and hydrogen with admixtures of the most promising alcohols: ethanol and butanol. The process of ignition of investigated blends behind reflected shock waves in the temperature range of 1000–1600 K and pressure range of 4.5–6 bar was studied. The te...
In this study the laser-induced incandescence (LII) diagnostics has been applied for sizing of carbon-encapsulated iron nanoparticles (CEINs). The carbon covered iron nanoparticles were synthesized by shock waves pyrolysis of the mixtures of Fe(CO)5 with C2H2 or C6H6 diluted with argon. Iron nanoparticles were formed in the shock tube behind incide...
In this work an influence of the wide range of various inhibitors, namely CCl4, CF3H, C2F4Br2, (CH3O)3P, CF3I and C3F7I on shock-induced ignition of hydrogen was experimentally investigated. Observed temperature dependencies of induction times indicates that CF3H and (CH3O)3P do not show noticeable inhibiting activity at given conditions, while the...
The work is devoted to application of a high sensitive and precise method of atomic resonance absorption spectroscopy for the measurements of the time profiles of concentration of various halogen atoms (chlorine, bromine, iodine), formed in pyrolysis of relevant inhibitors of combustion (CCl4, C2F4Br2, CF3I). The experiments were performed at tempe...
The influence of laser heated iron and carbon nanoparticles on ignition of 20 vol% stoichiometric methane–oxygen mixture in argon was studied experimentally in shock tube reactor. The concentration of nanoparticles 0.3–2.0 ppm was measured by laser light extinction. The particles were heated by Nd:Yag laser pulse operated at wavelength 1064 nm. The...
Measurements of atomic bromine and CF2 radical concentration profiles, formed at the dissociation of C2F4Br2 molecules behind shock waves, were carried out by means of atomic resonance absorption spectroscopy and molecular resonance absorption spectroscopy. The experiments were performed in mixtures with various concentrations of C2F4Br2 in Ar at t...
The nonequilibrium radiation in the spectral range of 210-415 nm at ignition of a 10% stoichiometric hydrogen-oxygen mixture with additives of combustion inhibitors diluted with argon behind shock waves was registered. The detected chemiluminescence is presumably attributed to electronically excited H2O* and H2O2 *. Instead of the expected quenchin...
In a recent paper (Eremin et al., 2017), the authors investigated the opposing influence of various fire suppressants based on the differences in the effects of halogenated hydrocarbons on the ignition of various combustible mixtures. It was shown that all the additives do not suppress, but some accelerate the ignition of methane/oxygen mixtures. A...
Using atomic resonance absorption spectroscopy, we measure the temporal profiles of Cl atom concentration at interaction with acetylene behind shock waves. We used CCl4 thermal decay as the chlorine atom source. We used a 30 ppm of CCl4 and 300 ppm of C2H2 in argon mixture for the experiments, at 1400–2300 K and pressures of about 2 bar. For experi...
A new experimental approach to the analysis of thermodynamic properties of amorphous carbon nanoparticles synthesized via hydrocarbon pyrolysis behind shock waves is discussed. The proposed approach is based on the analysis of thermal radiation of nanoparticles heated by a laser pulse. The sublimation temperature of the carbon nanoparticles might b...
Investigation of combustion of various mixtures is still a hot topic concerning the increase of application of various fuels as well as searching for replacement of fire suppressants [1] which produce environment pollutions and have a hazard of the climate change. Experimental study of ignition and combustion processes of simple substances such as...
Various halogenated hydrocarbons are widely used for fire extinguishing. Particularly, carbon tetrachloride, known as Halon-104, in spite of its noticeable toxicity and ozone-depleting properties still could be considered to be a perspective flame and detonation suppressant for unmanned facilities due to its quite high pyrolysis endothermicity and...
In the present study the carbon-encapsulated iron nanoparticles were synthesized by shock waves pyrolysis of the Fe(CO)5 vapor in the mixture with C2H2 or C6H6 diluted by argon. The iron nanoparticles were formed behind incident shock waves at the temperatures of 600–1200 K. The pyrolysis of hydrocarbons behind the reflected shock waves at the temp...
Experiments on acetylene and benzene pyrolysis with H 2 , O 2 , and CH 4 additions and following soot particle formation measured by laser extinction have been carried out behind reflected shock waves. Time-resolved temperature measurements during the induction time stated that the observed shifts of temperature dependences of soot formation in the...
The concentration of CF2 produced via trifluoromethane, CF3H, dissociation behind reflected shock waves is measured by molecular resonance absorption spectroscopy method within wide ranges of CF3H concentrations, temperatures, and pressures (38 ≤ n[CF3H] ≤ 27000 ppm, 1180 ≤ T ≤ 2780 K, and P = 1.5–18 bar). The heat release of CF2 radical formation...
The experiments were performed to investigate the influence of the flame suppressants CCl4, CF3H, and C2F4Br2 on the ignition of hydrogen–oxygen, acetylene–oxygen and methane–oxygen mixtures behind shock waves. The temperature dependencies of the ignition delay times and temperature profiles in the induction zone were measured. The experiments show...
The influence of small additions (0.3-2 ppm) of iron or carbon nanoparticles on ignition delay times in stoichiometric mixture of 20% (methane + oxygen) diluted in argon was investigated. The experiments were performed in 50 mm diameter shock tube behind reflected shock waves. The nanoparticles were synthesized in pyrolysis of 0.5-1% Fe(CO)5 and 1-...
The experimental investigation of iron-carbon nanoparticles synthesis by joint laser photolysis of iron pentacarbonyl in the mixture with methane or acetylene has been carried out. The radiation source used for photo-dissociation of precursors was a pulsed Nd:Yag laser operated at a wavelength of 266 nm. Under uv radiation the molecules of Fe(CO)5...
Nonmonotonous variation of the optical properties of iron nanoparticles with a temperature increase during heating behind reflected shock waves is discovered. Iron nanoparticles, within 12 nm in size, were formed at 0.5–1% Fe(CO)5 pyrolysis in argon behind the incident shock waves. Using a laser extinction method, a variation of the volume fraction...
In this study the laser photolysis of the mixtures containing vapors of various hydrocarbons and iron pentacarbonyl was implemented to nanoparticle formation. The radiation source used for photodissociation of precursors was a pulsed Nd:Yag laser operated at a wavelength of 266 nm. UnderUV radiation the molecules of Fe(CO)5 decomposed, forming atom...
This paper presents a numerical and experimental study of the effect of flame-retardant additives on the autoignition of methane behind shock waves. It is shown that at a temperature of 1300–1900 K, the compounds CCl4, CF3H, and (CH3O)3PO not only do not suppress ignition but significantly reduce the induction time of methane–oxygen mixtures. A kin...
This study is devoted to the investigation of molybdenum atom formation and consumption after UV laser pulse photolysis of molybdenum hexacarbonyl vapor diluted by various bath gases. The processes of formation and consumption of Mo atoms were observed using atomic resonance absorption spectroscopy (ARAS) technique at the Mo-I resonance line (λ = 3...
An influence of haloalkanes CF3H and CCl4 (known as inflammation and explosion suppressors) on combustion and pyrolysis of acetylene behind shock waves was experimentally studied. While ignition delay times in stoihiometric acetylene-oxygen mixtures were expectedly increased by halogenoalkanes admixtures, the induction times of carbon particle form...
Atomic resonance absorption spectroscopy has been used to study the yield of molybdenum atoms in the process of ultraviolet laser pulse photo-dissociation of Mo(CO)6 vapor. Molybdenum atoms in a ground state were formed by the quenching of the electronically excited Mo atoms generated during photolysis and were detected using the resonance absorpti...
Synthesis of iron-carbon nanoparticles in joint photolysis of iron pentacarbonyl (Fe(CO)5) and carbon tetrachloride (CCl4) has been studied. When mixtures containing iron pentacarbonyl and CCl4 are exposed to UV light, Fe(CO)5 molecules decompose to yield an atomic vapor of iron with well-known and easily controlled parameters, whereas CCl4 molecul...
In this paper we investigated experimentally the formation of a detonation wave as a result of energy release during pyrolysis of acetylene behind the shock wave. The kinetics and thermodynamics of the physical and chemical processes are analyzed; it is shown that the main heat release, which determines a positive integral energy balance of the det...
In this work, the laser-based synthesis and characterization of Mo nanoparticles formed using Kr-F laser pulse photolysis of the vapor of Mo(CO)6 diluted by argon at room temperature were carried out. The time-resolved laser-induced incandescence (Ti-Re LII) technique was applied for the sizing of aerosolized particle inside of the quartz reactor....
The peaks of nonequilibriumUVradiation froma small impurity of iodide molecules at the front of shock waves (SW) propagating in various inert gases (Ar, Ne, and He) and in hydrogen at equilibrium temperatures from 1300 to 2500 K were studied experimentally in [1]
A theoretical analysis that allows one to quantify the quantum corrections to the rate constants of endothermic reactions associated with an increase in the high-energy tails of the momentum distribution functions at high pressures due to a manifestation of the uncertainty principle for the energy of the colliding particles at a high collision freq...
This work is devoted to the experimental and theoretical study of charged carbon nanoparticles formed at the pyrolysis of various carbon-containing substances behind shock waves. The experimental results and the computer simulation of the electrical charging of carbon nanoparticles produced during the pyrolysis of C3O2, CCl4, and C6H6 in shock wave...
The influence of [TEX equation: \text{ CF }_{3}\text{ H }] and [TEX equation: \text{ CCl }_{4}] admixtures (known as detonation suppressors for combustible mixtures) on the development of acetylene detonation was experimentally investigated in a shock tube. The time-resolved images of detonation wave development and propagation were registered usin...
Simultaneous measurements of the temperature dependencies of the size, growth rate and relative yield of soot particles were carried out in the shock wave pyrolysis of various carbon-bearing species (carbon suboxide –C3O2, acetylene –C2H2 and benzene –C6H6). In all substances studied in the temperature ranges from 1800–2000 K to 2500–3000 K, a shar...
