Pub Date : 2024-09-11DOI: 10.1134/s1990793124700416
A. M. Tereza, G. L. Agafonov, E. K. Anderzhanov, A. S. Betev, S. P. Medvedev, V. N. Mikhalkin, S. V. Khomik, T. T. Cherepanova
Abstract
Numerical simulations of autoignition of lean (6% H2), stoichiometric, and rich (90% H2) hydrogen–air mixtures have been performed to examine the influence of third-body efficiency (chaperon efficiency, CE) on the value of ignition delay, τ. The temperature ranges explored in the computations are 850–1000 K for P0 = 1 bar and 1000–1200 K for P0 = 6 bar. By using a detailed kinetic mechanism, it has been found that the sensitivity of ignition delay to CE is the highest for the reaction step H + O2 + M = HO2 + M, which can lead to a variation in τ by a factor of 2 to 3. A pressure increase or deviation from stoichiometry reduces the sensitivity. The influence of CE is qualitatively different and weaker for the reaction step OH + OH + M = H2O2 + M.
摘要 对贫氢（6% H2）、化学计量和富氢（90% H2）氢气-空气混合物的自燃进行了数值模拟，以研究第三体效率（合子效率，CE）对点火延迟值τ的影响。计算中探讨的温度范围为：P0 = 1 巴时为 850-1000 K，P0 = 6 巴时为 1000-1200 K。通过使用详细的动力学机制，我们发现在 H + O2 + M = HO2 + M 的反应步骤中，点火延迟对 CE 的敏感性最高，可导致 τ 变化 2 到 3 倍。对于反应步骤 OH + OH + M = H2O2 + M，CE 的影响在性质上有所不同，而且较弱。
{"title":"The Role of Third-Body Collision Efficiency in Autoignition of Hydrogen–Air Mixtures","authors":"A. M. Tereza, G. L. Agafonov, E. K. Anderzhanov, A. S. Betev, S. P. Medvedev, V. N. Mikhalkin, S. V. Khomik, T. T. Cherepanova","doi":"10.1134/s1990793124700416","DOIUrl":"https://doi.org/10.1134/s1990793124700416","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Numerical simulations of autoignition of lean (6% H<sub>2</sub>), stoichiometric, and rich (90% H<sub>2</sub>) hydrogen–air mixtures have been performed to examine the influence of third-body efficiency (chaperon efficiency, CE) on the value of ignition delay, τ. The temperature ranges explored in the computations are 850–1000 K for <i>P</i><sub>0</sub> = 1 bar and 1000–1200 K for <i>P</i><sub>0</sub> = 6 bar. By using a detailed kinetic mechanism, it has been found that the sensitivity of ignition delay to CE is the highest for the reaction step H + O<sub>2</sub> + M = HO<sub>2</sub> + M, which can lead to a variation in τ by a factor of 2 to 3. A pressure increase or deviation from stoichiometry reduces the sensitivity. The influence of CE is qualitatively different and weaker for the reaction step OH + OH + M = H<sub>2</sub>O<sub>2</sub> + M.</p>","PeriodicalId":768,"journal":{"name":"Russian Journal of Physical Chemistry B","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-11DOI: 10.1134/s1990793124700398
A. L. Kusov, N. G. Bykova, G. Ya. Gerasimov, P. V. Kozlov, I. E. Zabelinsky, V. Yu. Levashov
Abstract
The results of modeling the radiation characteristics of the air behind the front of a strong shock wave, performed using the direct simulation Monte Carlo method, are presented. The model used takes into account various physical and chemical processes occurring in shock-heated air, including the translational-rotational and translational-vibrational energy exchange, kinetics of chemical reactions, and excitation of electronic levels of atoms and molecules, as well as the emission and absorption processes for a discrete spectrum. As a result of the calculations, time-integrated spectrograms of the volumetric radiation power of shock-heated air are obtained in absolute units in the range of shock wave velocities from 7.4 to 10.7 km/s at a gas pressure in front of the shock wave front of 0.25 Torr. The calculation data are compared with the experimental data obtained on a DDST-M double-diaphragm shock tube of the Institute of Mechanics of Moscow State University.
{"title":"Calculation of Radiation Characteristics of Shock-Heated Air by the Direct Simulation Monte Carlo Method","authors":"A. L. Kusov, N. G. Bykova, G. Ya. Gerasimov, P. V. Kozlov, I. E. Zabelinsky, V. Yu. Levashov","doi":"10.1134/s1990793124700398","DOIUrl":"https://doi.org/10.1134/s1990793124700398","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The results of modeling the radiation characteristics of the air behind the front of a strong shock wave, performed using the direct simulation Monte Carlo method, are presented. The model used takes into account various physical and chemical processes occurring in shock-heated air, including the translational-rotational and translational-vibrational energy exchange, kinetics of chemical reactions, and excitation of electronic levels of atoms and molecules, as well as the emission and absorption processes for a discrete spectrum. As a result of the calculations, time-integrated spectrograms of the volumetric radiation power of shock-heated air are obtained in absolute units in the range of shock wave velocities from 7.4 to 10.7 km/s at a gas pressure in front of the shock wave front of 0.25 Torr. The calculation data are compared with the experimental data obtained on a DDST-M double-diaphragm shock tube of the Institute of Mechanics of Moscow State University.</p>","PeriodicalId":768,"journal":{"name":"Russian Journal of Physical Chemistry B","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-11DOI: 10.1134/s1990793124700519
F. Mollaamin, M. Monajjemi
Abstract
Adsorption of toxic gas of carbon monoxide (CO) molecules by using transition metals (TM) of titanium (Ti), vanadium (V) or chromium (Cr)-doped boron nitride (B5N10) nanocage have been investigated using density functional theory. The partial density of states can evaluate a determined charge assembly between gas molecules and TM–B4N10 which indicates the competition among dominant complexes of Ti, V, Cr. Based on nuclear quadrupole resonance analysis, TM-doped on B5N10 has shown the lowest fluctuation in electric potential and the highest negative atomic charge including 0.5883 (chromium), 0.6893 (vanadium) and 0.7499 coulomb (titanium), respectively, have presented the most tendency for being the electron acceptors. Furthermore, the reported results of nuclear magnetic resonance spectroscopy have exhibited that the yield of electron accepting for doping atoms on the TM–B4N10 through gas molecules adsorption can be ordered as: Cr > V > Ti that exhibits the strength of covalent bond between titanium, vanadium, chromium, and CO towards toxic gas removal from air. In fact, the adsorption of CO gas molecules can introduce spin polarization on the TM–B4N10 which specifies that these surfaces may be employed as magnetic scavenging surface as a gas detector. Regarding IR spectroscopy, doped nanocages of Ti–B4N10, V–B4N10, and Cr–B4N10, respectively, have the most fluctuations and the highest adsorption tendency for gas molecules which can address specific questions on the individual effect of charge carriers (gas molecule-nanocage), as well as doping atoms on the overall structure. Based on the results of (Delta G_{{{text{ads}}}}^{{text{o}}}) amounts in this research, the maximum efficiency of Ti, V, Cr atoms doping of B5N10 for gas molecules adsorption depends on the covalent bond between CO molecules and TM–B4N10 as a potent sensor for air pollution removal. Therefore, for a given number of carbon donor sites in CO, the stabilities of complexes owing to doping atoms of Ti, V, Cr can be considered as: CO@Cr–B4N10 > CO@V–B4N10> CO@Ti–B4N10.
{"title":"Effect of Implanted Titanium, Vanadium or Chromium on Boron Nitride Surface for Increasing Carbon Monoxide Adsorption: Designing Gas Sensor for Green Chemistry Future","authors":"F. Mollaamin, M. Monajjemi","doi":"10.1134/s1990793124700519","DOIUrl":"https://doi.org/10.1134/s1990793124700519","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Adsorption of toxic gas of carbon monoxide (CO) molecules by using transition metals (TM) of titanium (Ti), vanadium (V) or chromium (Cr)-doped boron nitride (B<sub>5</sub>N<sub>10</sub>) nanocage have been investigated using density functional theory. The partial density of states can evaluate a determined charge assembly between gas molecules and TM–B<sub>4</sub>N<sub>10</sub> which indicates the competition among dominant complexes of Ti, V, Cr. Based on nuclear quadrupole resonance analysis, TM-doped on B<sub>5</sub>N<sub>10</sub> has shown the lowest fluctuation in electric potential and the highest negative atomic charge including 0.5883 (chromium), 0.6893 (vanadium) and 0.7499 coulomb (titanium), respectively, have presented the most tendency for being the electron acceptors. Furthermore, the reported results of nuclear magnetic resonance spectroscopy have exhibited that the yield of electron accepting for doping atoms on the TM–B<sub>4</sub>N<sub>10</sub> through gas molecules adsorption can be ordered as: Cr > V > Ti that exhibits the strength of covalent bond between titanium, vanadium, chromium, and CO towards toxic gas removal from air. In fact, the adsorption of CO gas molecules can introduce spin polarization on the TM–B<sub>4</sub>N<sub>10</sub> which specifies that these surfaces may be employed as magnetic scavenging surface as a gas detector. Regarding IR spectroscopy, doped nanocages of Ti–B<sub>4</sub>N<sub>10</sub>, V–B<sub>4</sub>N<sub>10</sub>, and Cr–B<sub>4</sub>N<sub>10</sub>, respectively, have the most fluctuations and the highest adsorption tendency for gas molecules which can address specific questions on the individual effect of charge carriers (gas molecule-nanocage), as well as doping atoms on the overall structure. Based on the results of <span>(Delta G_{{{text{ads}}}}^{{text{o}}})</span> amounts in this research, the maximum efficiency of Ti, V, Cr atoms doping of B<sub>5</sub>N<sub>10</sub> for gas molecules adsorption depends on the covalent bond between CO molecules and TM–B<sub>4</sub>N<sub>10</sub> as a potent sensor for air pollution removal. Therefore, for a given number of carbon donor sites in CO, the stabilities of complexes owing to doping atoms of Ti, V, Cr can be considered as: CO@Cr–B<sub>4</sub>N<sub>10</sub> > CO@V–B<sub>4</sub>N<sub>10</sub>> CO@Ti–B<sub>4</sub>N<sub>10</sub>.</p>","PeriodicalId":768,"journal":{"name":"Russian Journal of Physical Chemistry B","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214489","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-11DOI: 10.1134/s1990793124700568
P. V. Kozlov, M. A. Kotov, G. Ya. Gerasimov, V. Yu. Levashov, N. G. Bykova, I. E. Zabelinskii
Abstract
The self-ignition of a propylene–oxygen–argon stoichiometric mixture with a volumetric argon content of 95% is studied. The experiments are performed on a shock tube, which is part of the Shock Tube Experimental Complex of the Institute of Mechanics of Moscow State University, in conditions behind the reflected shock wave. The time dependencies of signals from a piezoelectric pressure sensor, a thermoelectric detector, and an optical section configured to record the radiation of electronically excited radicals OH• (λ = 302 nm), CH• (λ = 427 nm, and molecular carbon ({text{C}}_{2}^{centerdot }) (λ = 553 nm) are analyzed. The ignition delay times τign are measured in the temperature range T = 1200–2460 K and pressures p = 4.5–25 atm. The data obtained are compared with the results of other authors.
{"title":"Experimental Study of the Ignition of a Stoichiometric Propylene–Oxygen–Argon Mixture Behind a Reflected Shock Wave","authors":"P. V. Kozlov, M. A. Kotov, G. Ya. Gerasimov, V. Yu. Levashov, N. G. Bykova, I. E. Zabelinskii","doi":"10.1134/s1990793124700568","DOIUrl":"https://doi.org/10.1134/s1990793124700568","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The self-ignition of a propylene–oxygen–argon stoichiometric mixture with a volumetric argon content of 95% is studied. The experiments are performed on a shock tube, which is part of the Shock Tube Experimental Complex of the Institute of Mechanics of Moscow State University, in conditions behind the reflected shock wave. The time dependencies of signals from a piezoelectric pressure sensor, a thermoelectric detector, and an optical section configured to record the radiation of electronically excited radicals OH<sup>•</sup> (λ = 302 nm), CH<sup>•</sup> (λ = 427 nm, and molecular carbon <span>({text{C}}_{2}^{centerdot })</span> (λ = 553 nm) are analyzed. The ignition delay times τ<sub><i>ign</i></sub> are measured in the temperature range <i>T</i> = 1200–2460 K and pressures <i>p</i> = 4.5–25 atm. The data obtained are compared with the results of other authors.</p>","PeriodicalId":768,"journal":{"name":"Russian Journal of Physical Chemistry B","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-11DOI: 10.1134/s1990793124700593
E. A. Salgansky, M. V. Salganskaya, I. V. Sedov
Abstract
A new process is proposed for the pyrolysis of ammonia in a filtration combustion moving bed reactor to produce hydrogen. The process can be implemented in reactors with energy recovery with a separate supply of reagents (including swiss-roll reactors, etc.). The mass-energy balance of the process is calculated. The pyrolysis products are analyzed under a condition of thermodynamic equilibrium with varying temperature and pressure. The system pressure is varied from 1 to 10 bar. The temperature range from 300 to 1100 K iss considered. It is shown that the pyrolysis of ammonia ends at a temperature of 620 K at atmospheric pressure. An increase in pressure in the system leads to a slight increase in the temperature of the pyrolysis of ammonia. The portion of hydrogen that needs to be burned to cover the energy for heating and pyrolysis of the initial ammonia in the case of an adiabatic reactor is 0.13. From one mole of ammonia it is possible to obtain 1.31 moles of hydrogen.
{"title":"Thermodynamic Evaluation of Hydrogen Production Modes During the Pyrolysis of Ammonia in a Filtration Combustion Moving Bed Reactor","authors":"E. A. Salgansky, M. V. Salganskaya, I. V. Sedov","doi":"10.1134/s1990793124700593","DOIUrl":"https://doi.org/10.1134/s1990793124700593","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>A new process is proposed for the pyrolysis of ammonia in a filtration combustion moving bed reactor to produce hydrogen. The process can be implemented in reactors with energy recovery with a separate supply of reagents (including swiss-roll reactors, etc.). The mass-energy balance of the process is calculated. The pyrolysis products are analyzed under a condition of thermodynamic equilibrium with varying temperature and pressure. The system pressure is varied from 1 to 10 bar. The temperature range from 300 to 1100 K iss considered. It is shown that the pyrolysis of ammonia ends at a temperature of 620 K at atmospheric pressure. An increase in pressure in the system leads to a slight increase in the temperature of the pyrolysis of ammonia. The portion of hydrogen that needs to be burned to cover the energy for heating and pyrolysis of the initial ammonia in the case of an adiabatic reactor is 0.13. From one mole of ammonia it is possible to obtain 1.31 moles of hydrogen.</p>","PeriodicalId":768,"journal":{"name":"Russian Journal of Physical Chemistry B","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-11DOI: 10.1134/s1990793124700362
E. A. Salgansky, M. V. Salganskaya, D. O. Glushkov
Abstract
Using thermogravimetric analysis (TGA), the kinetic constants of the thermal decomposition of polymethylmethacrylate (PMMA) in an oxidizing environment are determined over a wide range of sample heating rates. The values of the kinetic constants of polymer decomposition are determined by the Kissinger method. It is shown that as the degree of polymer decomposition increases, the rate constant decreases at a constant temperature.
{"title":"Kinetics of Thermal Decomposition of Polymethylmethacrylate in an Oxidizing Environment","authors":"E. A. Salgansky, M. V. Salganskaya, D. O. Glushkov","doi":"10.1134/s1990793124700362","DOIUrl":"https://doi.org/10.1134/s1990793124700362","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Using thermogravimetric analysis (TGA), the kinetic constants of the thermal decomposition of polymethylmethacrylate (PMMA) in an oxidizing environment are determined over a wide range of sample heating rates. The values of the kinetic constants of polymer decomposition are determined by the Kissinger method. It is shown that as the degree of polymer decomposition increases, the rate constant decreases at a constant temperature.</p>","PeriodicalId":768,"journal":{"name":"Russian Journal of Physical Chemistry B","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-11DOI: 10.1134/s1990793124700404
B. S. Seplyarskii, R. A. Kochetkov, T. G. Lisina, N. I. Abzalov
Abstract
The combustion modes of powder and granular mixtures (100 – X)(Ti + C) + XNiCr (X = 0–30%) containing Ti powders of different dispersion with different amounts of impurity gases in them are studied. The experimental setup provided the filtration of impurity gases released during combustion in the cocurrent direction or through the side surface of the sample. The difference between the experimental burning velocities of powder mixtures with titanium of a different fineness is explained using a convective-conductive combustion model. For granular mixtures based on Ti powder with a characteristic size of 120 μm, it is shown that combustion occurs in the conductive mode. Comparison of the combustion velocities of granular mixtures containing Ti powder with particles of a characteristic size of 60 μm in the absence and presence of gas filtration through the sample indicates the transition of combustion to the convective regime. The necessary and sufficient conditions for the transition from conductive to convective combustion are formulated, which makes it possible to determine the composition of the mixture whose combustion occurs in the boundary region. In mixtures based on Ti with a particle size of 60 μm, the conductive combustion regime is observed during the combustion of granules 0.6 mm in size and a mixture with X = 30% of granules 1.7 mm in size. For mixtures with X = 0–20% with granules 1.7 mm in size, burning in the convective regime, the interfacial heat transfer coefficients are evaluated using the experimental data. Their values are more than an order of magnitude higher than the theoretical ones. The XRD results of the combustion products showed that in order to obtain synthesis products without side phases of intermetallic compounds, it is necessary to use finely dispersed titanium powder.
摘要 研究了粉末和颗粒混合物 (100 - X)(Ti + C) + XNiCr (X = 0-30%)的燃烧模式，这些混合物含有不同分散度的 Ti 粉末和不同数量的杂质气体。实验装置可过滤燃烧过程中顺流方向或通过样品侧表面释放的杂质气体。使用对流-传导燃烧模型解释了不同细度钛粉末混合物实验燃烧速度之间的差异。对于基于特征尺寸为 120 μm 的钛粉的颗粒混合物，研究表明燃烧发生在传导模式下。比较了含有特征粒度为 60 μm 的钛粉颗粒的颗粒混合物在没有和有气体过滤通过样品的情况下的燃烧速度，结果表明燃烧过渡到了对流状态。我们提出了从传导燃烧过渡到对流燃烧的必要条件和充分条件，从而可以确定在边界区域发生燃烧的混合物的成分。在以粒径为 60 μm 的钛为基础的混合物中，粒径为 0.6 mm 的颗粒和粒径为 1.7 mm 的颗粒占 X = 30% 的混合物在燃烧过程中会出现传导燃烧。对于 X = 0-20% 的颗粒大小为 1.7 毫米的混合物，在对流状态下燃烧时，利用实验数据评估了界面传热系数。其值比理论值高出一个数量级以上。燃烧产物的 XRD 结果表明，为了获得没有金属间化合物副相的合成产物，必须使用精细分散的钛粉。
{"title":"Conductive and Convective Combustion Modes of Granular Mixtures of Ti–C–NiCr","authors":"B. S. Seplyarskii, R. A. Kochetkov, T. G. Lisina, N. I. Abzalov","doi":"10.1134/s1990793124700404","DOIUrl":"https://doi.org/10.1134/s1990793124700404","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The combustion modes of powder and granular mixtures (100 – <i>X</i>)(Ti + C) + <i>X</i>NiCr (<i>X</i> = 0–30%) containing Ti powders of different dispersion with different amounts of impurity gases in them are studied. The experimental setup provided the filtration of impurity gases released during combustion in the cocurrent direction or through the side surface of the sample. The difference between the experimental burning velocities of powder mixtures with titanium of a different fineness is explained using a convective-conductive combustion model. For granular mixtures based on Ti powder with a characteristic size of 120 μm, it is shown that combustion occurs in the conductive mode. Comparison of the combustion velocities of granular mixtures containing Ti powder with particles of a characteristic size of 60 μm in the absence and presence of gas filtration through the sample indicates the transition of combustion to the convective regime. The necessary and sufficient conditions for the transition from conductive to convective combustion are formulated, which makes it possible to determine the composition of the mixture whose combustion occurs in the boundary region. In mixtures based on Ti with a particle size of 60 μm, the conductive combustion regime is observed during the combustion of granules 0.6 mm in size and a mixture with <i>X</i> = 30% of granules 1.7 mm in size. For mixtures with <i>X</i> = 0–20% with granules 1.7 mm in size, burning in the convective regime, the interfacial heat transfer coefficients are evaluated using the experimental data. Their values are more than an order of magnitude higher than the theoretical ones. The XRD results of the combustion products showed that in order to obtain synthesis products without side phases of intermetallic compounds, it is necessary to use finely dispersed titanium powder.</p>","PeriodicalId":768,"journal":{"name":"Russian Journal of Physical Chemistry B","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-11DOI: 10.1134/s1990793124700532
A. A. Belyaev, B. S. Ermolaev
Abstract
Small additions of hydrocarbons, such as propylene, which are widely studied as combustion and explosion inhibitors of hydrogen-air mixtures, sometimes exhibit specific properties. The known mechanism of the inhibitory effect of these additives is associated with the intensification of the termination of branching chains due to the addition of hydrogen atoms; however, conditions also exist in which these compounds, instead of inhibiting, have a neutral and even promoting effect. Such conditions and the reasons leading to the fact that inhibition is practically absent have not yet been studied. This article shows the results of numerical modeling, which make it possible to more fully outline the range of conditions where the addition of propylene practically does not inhibit hydrogen-air mixtures and outline possible reasons for this effect. The solution to three model problems is presented: self-ignition in a constant-volume reactor, laminar flame propagation, and gas ignition with a heated wire. The calculations are carried out with the detailed kinetic mechanism of chemical reactions NUIGMech 1.1 (2020). The objects of the study are three air mixtures containing hydrogen in amounts of 15, 29.6, and 50 vol % (lean, stoichiometric, and rich mixtures, respectively) without additives and with the addition of 1% propylene.
{"title":"Features of the Inhibition of Hydrogen-Air Mixtures by Propylene Additive","authors":"A. A. Belyaev, B. S. Ermolaev","doi":"10.1134/s1990793124700532","DOIUrl":"https://doi.org/10.1134/s1990793124700532","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Small additions of hydrocarbons, such as propylene, which are widely studied as combustion and explosion inhibitors of hydrogen-air mixtures, sometimes exhibit specific properties. The known mechanism of the inhibitory effect of these additives is associated with the intensification of the termination of branching chains due to the addition of hydrogen atoms; however, conditions also exist in which these compounds, instead of inhibiting, have a neutral and even promoting effect. Such conditions and the reasons leading to the fact that inhibition is practically absent have not yet been studied. This article shows the results of numerical modeling, which make it possible to more fully outline the range of conditions where the addition of propylene practically does not inhibit hydrogen-air mixtures and outline possible reasons for this effect. The solution to three model problems is presented: self-ignition in a constant-volume reactor, laminar flame propagation, and gas ignition with a heated wire. The calculations are carried out with the detailed kinetic mechanism of chemical reactions NUIGMech 1.1 (2020). The objects of the study are three air mixtures containing hydrogen in amounts of 15, 29.6, and 50 vol % (lean, stoichiometric, and rich mixtures, respectively) without additives and with the addition of 1% propylene.</p>","PeriodicalId":768,"journal":{"name":"Russian Journal of Physical Chemistry B","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-11DOI: 10.1134/s1990793124700611
V. E. Khrapovskii, V. G. Khudaverdiev, A. A. Sulimov, P. V. Komissarov, S. S. Basakina
Abstract
The ignition of the normal layer-by-layer burning (LB) and its transition to the convective burning (CB) regime in mixtures of ammonium nitrate (AN) with bulk density aluminum are studied. Experiments in a constant-volume bomb with pressure registration are carried out. The porosity of the samples is 0.55–0.59, the particle size of the AN varies from 20–40 to 250–630 µm, and the aluminum content varies from 8 to 47 wt %. Two brands of aluminum were used: ASD-4 and PAP-2. It is shown that the mixtures are capable of being ignited when the igniter pressure is close to or above the critical (minimum) value. The values of the critical pressure of the igniter, the pressure, and the time at which LB and CB occurs for mixtures with different particle sizes of AN and aluminum and different concentrations are measured. The replacement of aluminum ASD-4 with PAP‑2 leads to a significant (by an order of magnitude or even more) decrease in the values of critical pressure and pressures at which LB and CB begins.
{"title":"The Effect of Aluminum in Its Mixtures With Ammonium Nitrate on the Ignition of Burning and Its Transition to the Convective Burning Regime","authors":"V. E. Khrapovskii, V. G. Khudaverdiev, A. A. Sulimov, P. V. Komissarov, S. S. Basakina","doi":"10.1134/s1990793124700611","DOIUrl":"https://doi.org/10.1134/s1990793124700611","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The ignition of the normal layer-by-layer burning (LB) and its transition to the convective burning (CB) regime in mixtures of ammonium nitrate (AN) with bulk density aluminum are studied. Experiments in a constant-volume bomb with pressure registration are carried out. The porosity of the samples is 0.55–0.59, the particle size of the AN varies from 20–40 to 250–630 µm, and the aluminum content varies from 8 to 47 wt %. Two brands of aluminum were used: ASD-4 and PAP-2. It is shown that the mixtures are capable of being ignited when the igniter pressure is close to or above the critical (minimum) value. The values of the critical pressure of the igniter, the pressure, and the time at which LB and CB occurs for mixtures with different particle sizes of AN and aluminum and different concentrations are measured. The replacement of aluminum ASD-4 with PAP‑2 leads to a significant (by an order of magnitude or even more) decrease in the values of critical pressure and pressures at which LB and CB begins.</p>","PeriodicalId":768,"journal":{"name":"Russian Journal of Physical Chemistry B","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-11DOI: 10.1134/s199079312470057x
S. S. Kostenko, A. N. Ivanova, A. A. Karnaukh, E. V. Polianczyk
Abstract
A numerical model for the POX steam-oxygen conversion of methane to synthesis gas in a reversed flow nonpremixed filtration combustion reactor with a reversed flow of a steam-methane mixture and a continuous supply of oxygen to the center of the reactor is carried out. The calculations were performed for the oxygen/methane molar ratio of 0.47 and steam/methane molar ratio of 0.5, in the parametric region close to the limit for the feasibility of the scheme. Various modes of initiation and control of flow reversal are considered, and dependences of the combustion temperature and the composition of products on the characteristics of the process are obtained. A comparison of the established cyclic mode of conversion with the predictions of the equilibrium model shows that the kinetic constraints lead to a higher combustion temperature and incomplete conversion of methane. At high temperatures, the conversion proceeds via the initial soot formation during the pyrolysis of methane and the subsequent reaction of soot with steam.
{"title":"Numerical Simulation of Oxidative Conversion of Methane to Synthesis Gas in a Reversed Flow Reactor","authors":"S. S. Kostenko, A. N. Ivanova, A. A. Karnaukh, E. V. Polianczyk","doi":"10.1134/s199079312470057x","DOIUrl":"https://doi.org/10.1134/s199079312470057x","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>A numerical model for the POX steam-oxygen conversion of methane to synthesis gas in a reversed flow nonpremixed filtration combustion reactor with a reversed flow of a steam-methane mixture and a continuous supply of oxygen to the center of the reactor is carried out. The calculations were performed for the oxygen/methane molar ratio of 0.47 and steam/methane molar ratio of 0.5, in the parametric region close to the limit for the feasibility of the scheme. Various modes of initiation and control of flow reversal are considered, and dependences of the combustion temperature and the composition of products on the characteristics of the process are obtained. A comparison of the established cyclic mode of conversion with the predictions of the equilibrium model shows that the kinetic constraints lead to a higher combustion temperature and incomplete conversion of methane. At high temperatures, the conversion proceeds via the initial soot formation during the pyrolysis of methane and the subsequent reaction of soot with steam.</p>","PeriodicalId":768,"journal":{"name":"Russian Journal of Physical Chemistry B","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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