Science topic

# Chemical Kinetics - Science topic

Prediction, assessments and studies on the composition of reaction mixtures as a function of time, to understand the processes that occur during a reaction, and to identify what controls its rate.
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Publications related to Chemical Kinetics (10,000)
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Article
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Progressively stricter pollutant emission targets in international agreements have shifted the focus of combustion research to low carbon fuels. Ammonia is recognized as one of the promising energy vectors for next-generation power production. Due to the low flame speed and high auto-ignition temperature, ammonia is often burned with a high reactiv...
Article
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A numerical and experimental investigation about the chemical kinetic interactions between 2-ethylhexylnitrate (EHN) and PRF91 was performed in this study. Rapid compression machine experiments were conducted to investigate the effect of EHN on the autoignition reactivity of the fuel, and a reduced chemical kinetic mechanism was developed including...
Article
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In this study, the effects of doping a regular E10 gasoline with 2-ethlyhexyl nitrate (EHN) are investigated under homogeneous charge compression ignition conditions. Experiments are performed in a 1-liter single-cylinder engine fueled with both straight and EHN-doped E10 gasoline. Numerical studies are performed with an internal combustion engine...
Article
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This study investigates soot inception limits of laminar coflow diffusion flames in the carbon-to-oxygen atom (C/O) ratio space, as well as the mechanism of flame structure affecting soot inception. And chemiluminescence characteristics in flames are evaluated. Oxy-ethylene flames with the same adiabatic flame temperature (2500 K) and different sto...
Article
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The notions of regularity and characteristic width of detonation cells are revisited based on crossed analyses of experimental front-view and longitudinal recordings obtained with the soot-plate technique. Tubes with cross-sections of different shapes, namely round, triangular and square, but the same surface area of 16 cm2, are used to detonate th...
Article
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Laminar burning velocities (LBV) and Markstein lengths of spherical flames of n-heptane (H), iso-octane (O), and ethanol (E) and their binary and ternary mixtures (in equal volume fractions) at elevated pressures and temperatures are experimentally investigated. Measurements are performed in a constant volume combustion vessel using two distinct te...
Article
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Machine learning has long been considered a black box for predicting combustion chemical kinetics due to the extremely large number of parameters and the lack of evaluation standards and reproducibility. The current work aims to understand two basic questions regarding the deep neural network (DNN) method: what data the DNN needs and how general th...
Article
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A concise kinetic model catering for the antioxidant reaction of thermally aged cross‐linked polyethylene (XLPE) cable insulation before its abrupt performance deterioration is proposed for life prediction and condition assessment. The alternating current breakdown strength, elongation at break, carbonyl index, and pyrolysis activation energy of XL...
Book
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Chemical Kinetics, an important branch of Physical Chemistry is the study of chemical reactions and is well researched all over the world. A course in Chemical Kinetics is an essential part of Chemistry curricula worldwide. Chemical Kinetics finds important applications in diverse fields. The aim of this book is to introduce the basic concepts of C...
Article
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The combustion phenomena are always complex in nature due to the involvement of complex series and parallel reactions. There are various methods that are involved in analyzing combustion phenomena. Viscosity is the first and foremost factor that acts as the DNA of fuel. By evaluating the viscosity, it is possible initially to understand the combust...
Article
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The total reduction of Cr(VI) by microsecond pin-to-pin electric discharge generated in aqueous solution has been reported. [Cr(VI)] and [H2O2] were measured simultaneously by UV–Vis absorption spectroscopy during the process. The kinetics of the Cr(VI) reduction resulting from the discharges is found to be pseudo zero order rate. The influence of...
Preprint
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Chemical kinetics mechanisms are essential for understanding, analyzing, and simulating complex combustion phenomena. In this study, a Neural Ordinary Differential Equation (Neural ODE) framework is employed to optimize kinetics parameters of reaction mechanisms. Given experimental or high-cost simulated observations as training data, the proposed...
Article
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Modelling atmospheric composition and climate change on the global scale remains a great scientific challenge. Earth system models spend up to 85% of their total required computational resources on the integration of atmospheric chemical kinetics. We refactored a general atmospheric chemical kinetics solver system to maintain accuracy in single pre...
Article
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This paper presents a joint numerical and experimental study of the ignition process and flame structures in a gasoline partially premixed combustion (PPC) engine. The numerical simulation is based on a five-dimension Flamelet-Generated Manifold (5D-FGM) tabulation approach and large eddy simulation (LES). The spray and combustion process in an opt...
Article
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Chemical kinetics and thermodynamics provide modes and mechanisms for the thermal death of microbial spores. In this study, the effect of thermal inactivation on Geobacillus stearothermophilus, a highly heat-resistant bacterial species, was studied over the temperature range of 95, 100, 105, and 110 °C and holding sterilization periods of 10, 15, 2...
Article
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The CO2(¹B2) - CO2(X¹Σ⁺g) transition is a source of chemiluminescence from CO and hydrocarbon premixed flames and can be used as a diagnostic; however, its chemistry is not well known due to its broadband nature. Although several attempts have been made to model CO2(¹B2) chemiluminescence, none performs well in hydrocarbon flames. We propose a new...
Article
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Accumulation of the amyloid-$$\beta$$ (A$$\beta$$ ) peptide in the brain gives rise to a cascade of key events in the pathogenesis of Alzheimer’s disease (AD). It is verified by different research trials that the sleep-wake cycle directly affects A$$\beta$$ levels in the brain. The catalytic nature of amyloidosis and the protein aggregation can...
Article
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The use of H2O2, CH2O, H2O, CH4, C2H5OH, CHOCHO and CH3CHO as additives in rich methanol/air mixtures is investigated for the control of ignition delay and of the super adiabatic temperature phenomenon (SAT) during autoignition. Since H2O2 acts as an oxidizer, effectively it shifts the process to smaller equivalence ratios, which none of the other...
Article
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The current work aims to examine how the nature of cellular instabilities controls the re-initiation capability and dynamics of a gaseous detonation transmitting across a layer of inert (or non-detonable) gases. This canonical problem is tackled via computational analysis based on the two-dimensional, reactive Euler equations. Two different chemica...
Article
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Chemodynamic therapy (CDT) is a kind of anti-tumor strategy emerging in recent years, but the concentration of hydrogen peroxide (H 2 O 2 ) in the tumor microenvironment is insufficient, and it is difficult for a single CDT to completely inhibit tumor growth. Here, we designed a CuS nanoparticles (NPs) and camptothecin (CPT) co-loaded thermosensiti...
Article
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A CFD model based on the Reynolds Averaged Navier–Stokes (RANS) approach combined with a detailed chemical kinetic mechanism to investigate a turbulent CH4/H2/N2 jet diffusion flame is developed. The CFD governing equations of momentum, mass, and energy in the turbulent field were solved in conjunction with the standard k − ε turbulence model. The...
Article
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The present study is an extension of our prior study on the external group combustion (EGC) of droplet clouds under two-stage autoignition conditions [Zhou and Liu, Combust. Flame 234 (2021) 111689]. Effects of droplet heating and different n-alkane fuel candidates have been further considered. By comparing numerical results from n-heptane and n-do...
Preprint
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Physics-informed neural networks (PINNs) have recently received much attention due to their capabilities in solving both forward and inverse problems. For training a deep neural network associated with a PINN, one typically constructs a total loss function using a weighted sum of different loss terms and then tries to minimize that. This approach o...
Article
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The global atmospheric chemical transport model has become a key technology for air quality forecast and management. However, precise and rapid air quality simulations and forecast are frequently limited by the model’s computational performance. The gas-phase chemistry module is the most time-consuming module in air quality models because its tradi...
Article
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Ammonia-based selective catalytic reduction is one of the most effective NOx reduction technologies for diesel engines, but its low NOx reduction efficiency under low-temperature conditions needs further improvement. Previous studies have broadened our understanding of the NH3 adsorption and desorption that occurs in an SCR catalyst of Cu ion-excha...
Article
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Modeling of the chemistry and thermodynamics is crucial in numerical simulations that attempt to accurately simulate reactive flows such as flame acceleration and detonation phenomena. The current study explores how a four-species, four-step combustion mechanism performs to predict ignition processes in various premixed hydrocarbon fuel mixtures wh...
Article
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Statistical equations are widely used to describe the laws of various chemical technological processes. The values of constants and parameters included in these equations are determined by various methods. Methods that can determine the values of equation parameters using a limited amount of experimental data are of particular practical interest. I...
Article
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C5F10O-insulated environmental-friendly power equipment has great potential to be used in the near future to reduce greenhouse effect. During maintenance, C5F10O should be supplemented or replaced, and the released gas is promisingly to be removed by advanced oxidation processes, but chemical kinetics of C5F10O with the most reactive and dominant s...
Preprint
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Background: In May 2022, monkeypox started to spread in non-endemic countries. After the number of confirmed cases reached more than 16,000 in July, the World Health Organization declared the highest alert over the outbreak. Methods: To investigate the effects of contact tracing and self-reporting of primary cases in the local community, a stochas...
Article
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Solid‐state electrolytes (SSEs) formed inside an electrochemical cell by polymerization of a liquid precursor provide a promising strategy for overcoming problems with electrolyte wetting in solid‐state batteries. Hybrid solid‐state polymer electrolytes (HSPEs) created by in situ polymerization of a conventional liquid precursor containing electroc...
Preprint
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Volcanism is a major and long-term source of volatile elements such as C and H to Earth's atmosphere, likely has been to Venus's atmosphere, and may be for exoplanets. Models simulating volcanic growth of atmospheres often make one of two assumptions: either that atmospheric speciation is set by the high temperature equilibrium of volcanism; or, th...
Article
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Cyclohexene is an important intermediate during the oxidation of cycloalkanes, which comprise a significant portion of real fuels. Thus, experimental data sets and kinetic models of cyclohexene play an important role in the understanding of the combustion of cycloalkanes and real fuels. In this work, an experimental and kinetic modeling study of th...
Preprint
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We introduce Catalyst.jl, a flexible and feature-filled Julia library for modeling and high performance simulation of chemical reaction networks (CRNs). Catalyst acts as both a domain specific language and an intermediate representation for symbolically encoding CRN models as Julia-native objects. This enables a pipeline of symbolically specifying,...
Article
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This study introduces the gradient boosted decision tree (GBDT) as a machine learning approach to circumvent the need for a direct integration of the typically stiff system of ordinary differential equations that govern the temporal evolution of chemically reacting species. Stiffness primarily relates to the chemistry integration and here, hydrogen...
Article
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Understanding the dynamics induced by confined thermo-chemical processes occurring inside a solid medium is a fundamental problem of interest in several applications, such as hotspot formation and micro-explosions in energetic materials and laser-induced cavitation for energy focusing and material characterization. In recent years, advanced experim...
Article
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For artificial photosynthesis, the lower photon conversion efficiencies of the photogenerated charges hinder the practical application in solar energy harvesting. The challenges are commonly ascribed to the sluggish surface redox reactions and significant surface charge recombination. Although there are several transient techniques applied for moni...
Article
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Chemical models and experiments indicate that interstellar dust grains and their ice mantles play an important role in the production of complex organic molecules (COMs). To date, the most complex solid-phase molecule detected with certainty in the interstellar medium is methanol, but the James Webb Space Telescope (JWST) may be able to identify st...
Article
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Succinic acid has attracted much interest as a key platform chemical that can be obtained in high titers from biomass through sustainable fermentation processes, thus boosting the bioeconomy as a critical production strategy for the future. After several years of development of the production of succinic acid, many studies on lab or pilot scale pro...
Article
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Nanomaterials, today, are an integral part of our everyday lives, industrial processes and appliances. Biosynthesis, because of its environmental sustainability, is now becoming a hot topic. The biosynthesis of nanomaterials using plant phytochemicals enhances the nanomaterial’s biocompatibility and its compatibility with the environment too. Hence...
Article
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This study determined the difficulty level of answering Chemistry problems of the STEM students of Libertad National High School. The respondents of the study were seventy-three (73) purposely selected students for the school year 2020-2021. Thereafter, the researcher developed a Learning Package in Chemistry to augment the learning in the new norm...
Preprint
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The RMG-database for chemical property prediction is presented. The RMG-database consists of curated datasets and estimators for accurately predicting parameters necessary for constructing a wide variety of chemical kinetic mechanisms, including thermodynamics, kinetics, solvation effects, and transport properties. For thermochemistry prediction, t...
Article
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Converter gas (BOFG) is a by-product of the steel manufacturing process in steelworks. Its usage as a substitute fuel instead of natural gas for fueling a metallurgical furnace seems to be reasonable due to potential benefits as follows: CO2 emission reduction into the ambient air and savings in purchasing costs of natural gas. Results of theoretic...
Preprint
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Kinetic integration of large and stiff chemical mechanisms is a computational bottleneck in models of atmospheric chemistry. It requires implicit solution of the coupled system of kinetic differential equations with time-consuming construction and inversion of the Jacobian matrix. We present here a new version of the Kinetic Pre-Processor (KPP 3.0....
Article
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Increase in anthropogenic greenhouse gases such as carbon dioxide has contributed to global warming and climate change. One of the mitigation strategies is to decompose CO2 into useful products, and the dielectric barrier discharge plasma can be utilized for the decomposition process. To study the CO2 decomposition process, a zero-dimensional chemi...
Article
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Cadmium (Cd) is one of the heavy metals with a high level of contaminants that is environmentally harmful and can interfere with human health. This study aims to determine the adsorption capacity and adsorption kinetics of Cd (II) from Matoa fruit peel activated by nitric acid. The adsorption method can be used to treat Cd (II) waste in the water....
Conference Paper
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Flame spread over solid fuels is a canonical problem in fire science, due to its direct implications on material flammability and importance in fire development. Flames in a microgravity environment can behave very differently than on Earth, posing additional risks for spaceflight life safety. Sub-atmospheric pressures in ground-based experiments h...
Article
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The identification of undergraduate chemistry students’ conceptual difficulties and common mistakes with basic concepts and problems in chemical kinetics provided the aim for this study, which involved 2nd-year/4th semester students who had passed the chemical kinetics component of a physical chemistry course. The study involved the analysis, evalu...
Article
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A numerical simulation was used to investigate an approach of reduction of the chemical kinetics coupled with two methods: Computational Singular Perturbation (CSP) and Directed Relation Graph with Propagation Error (DRGEP), in order to simulate the laminar premixed Biogas diluted by the H2-CO2. In this reduction approach, DRGEP allowed the identif...
Article
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The present work aims to evaluate the performance of the constant-volume method by several sets of experiments carried out in three different closed vessels (a sphere and two cylinders) analyzing the obtained results in order to obtain accurate laminar burning velocities. Accurate laminar burning velocities can be used in the development of computa...
Article
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This paper presents the kinetics of methanol synthesis from carbon dioxide and hydrogen over a Cu/Zn/Zr/Ga catalyst. Kinetic studies were carried out in a continuous-flow fixed-bed reactor in a temperature range from 433 to 513 K, pressures from 3 to 8 MPa, and GHSV from 1660 to 10,000 1/h for initial molar fractions of hydrogen from about 0.48 to...
Preprint
Full-text available
Chemical models and experiments indicate that interstellar dust grains and their ice mantles play an important role in the production of complex organic molecules (COMs). To date, the most complex solid-phase molecule detected with certainty in the ISM is methanol, but the James Webb Space Telescope (JWST) may be able to identify still larger organ...
Article
Full-text available
Thermodynamic modeling helps to reveal insights into the basic chemical kinetics of dissolution and precipitation in cementitious materials, but relevant applications to cement-stabilized soils have seldom been reported. Based on the thermodynamic database of Cemdata18 and the pore solution composition of cement-stabilized soils, this study formula...
Article
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Manifold based simplified chemistry is an efficient reduction technique for the chemical kinetics, which aims to reduce the computational effort in numerical simulations. While the concept of reduced chemistry has been used for decades and various models have been developed till now, their coupling with turbulent physical processes (e.g. mixing pro...
Article
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Many researchers believe multi-zone (MZ), chemical kinetics–based models are proven, essential toolchains for development of low-temperature combustion (LTC) engines. However, such models are specific to the research groups that developed them and are not widely available on a commercial nor open-source basis. Consequently, their governing assumpti...
Article
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A numerical study has been carried out to evaluate the influence of ozone addition on the laminar flame speed for both methane/air and isooctane/air mixtures under thermodynamic conditions typical of internal combustion engines. Ozone is a highly oxidising chemical species and modifies the fuel oxidation reaction pathways, mainly in the initial sta...
Article
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Esterases represent a class of hydrolases, and are widely distributed in animals, plants and microorganisms. Depending on whether they hydrolyze small water-soluble esters or ester bonds of long-chain acylglycerols, they are classified as carboxylesterases (EC 3.1.1.1) or lipases (EC 3.1.1.3). A host of novel microbial carboxylesterases from cultur...