scholarly journals Modeling of Isocyanate Synthesis by the Thermal Decomposition of Carbamates

Computation ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 89
Author(s):  
Ratmir Dashkin ◽  
Georgii Kolesnikov ◽  
Pavel Tsygankov ◽  
Igor Lebedev ◽  
Artem Lebedev ◽  
...  
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Mathematical Model ◽  
Thermal Decomposition ◽  
Computer Models ◽  
Computational Experiments ◽  
Comsol Multiphysics ◽  
Suggested Model ◽  
Exponential Factor ◽  
Calculation Results

The presented work is devoted to isocyanate synthesis by the thermal decomposition of carbamates model. The work describes the existing isocyanate-obtaining processes and the main problems in the study of isocyanate synthesis by the thermal decomposition of carbamates, which can be solved using mathematical and computer models. Experiments with carbamates of various structures were carried out. After processing the experimental data, the activation energy and the pre-exponential factor for isocyanate synthesis by the thermal decomposition of carbamates were determined. Then, a mathematical model of the reactor for the thermal decomposition of carbamates using the COMSOL Multiphysics software was developed. For this model, computational experiments under different conditions were carried out. It was shown that the calculation results correspond to the experimental ones, so the suggested model can be used in the design of the equipment for isocyanate synthesis by the thermal decomposition of carbamates.

scholarly journals Kinetic Parameters for the Thermal Decomposition of Forest Waste Using Distributed Activation Energy Model (DAEM)

2017 ◽  
Vol 19 (1) ◽  
pp. 15-32 ◽  
Author(s):  
Alok Dhaundiyal ◽  
Pramod Tewari
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Thermal Decomposition ◽  
Asymptotic Expansion ◽  
Nitrogen Atmosphere ◽  
Energy Model ◽  
Pine Needle ◽  
Distributed Activation Energy Model ◽  
Exponential Factor ◽  
Forest Waste

Abstract The purview of paper pivoted around the pyrolysis decomposition of forest waste (pine needle litter) by thermogravimetric analysis (TGA). Experiments were carried out in the presence of Nitrogen atmosphere. The experimental data was compared with those obtained by numerical solution of distributed activation energy model (DAEM). Asymptotic expansion is adopted to evaluate the pre-exponential factor, mean activation energy and variance. The correction factor Bi has been invoked to describe accurately the differential thermogravitmeric curves of thermal decomposition of pine needles.

Studies on the Thermal Decomposition Kinetic of an Nitrate Ester

2012 ◽  
Vol 182-183 ◽  
pp. 1575-1580 ◽  
Author(s):  
Juan Wang ◽  
Da Bin Liu ◽  
Xin Li Zhou
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Decomposition Mechanism ◽  
Thermal Decomposition Mechanism ◽  
Decomposition Kinetic ◽  
Heating Rates ◽  
Exponential Factor ◽  
Nitrate Ester ◽  
Dynamic Function ◽  
Thermal Decomposition Kinetic

The certain nitrate ester explosive has been tested by TG at the heating rates of 10, 15, 20, 25K•min-1. Basing on the TG experiment results the thermal decomposition activation energy has been calculated by the methods of Ozawa, KAS and iteration. And the thermal decomposition mechanism function of the explosive with 38 kinds of dynamic function was deduced by the method of integration. The results show that the thermal decomposition mechanism of the nitrate ester is chemical reaction mechanism. The thermal decomposition kinetic parameters such as average activation energy Ea and pre-exponential factor A are 133.23×103 J•mol-1 and 3.191×107 s-1 respectively.

scholarly journals Thermal decomposition characteristics of foundry sand for cast iron in nitrogen atmosphere

2018 ◽  
Vol 5 (12) ◽  
pp. 181091 ◽  
Author(s):  
Qingwei Xu ◽  
Kaili Xu ◽  
Xiwen Yao ◽  
Jishuo Li ◽  
Li Li
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Cast Iron ◽  
Low Cost ◽  
Temperature Stability ◽  
Nitrogen Atmosphere ◽  
High Temperature Stability ◽  
Kinetics Parameters ◽  
Foundry Sand ◽  
Exponential Factor

Sand casting, currently the most popular approach to the casting production, has wide adaptability and low cost. The thermal decomposition characteristics of foundry sand for cast iron were determined for the first time in this study. Thermogravimetry was monitored by simultaneous thermal analyser to find that there was no obvious oxidation or combustion reaction in the foundry sand; the thermal decomposition degree increased as the heating rate increased. There was an obvious endothermic peak at about 846 K due to the transition of quartz from β to α phase. A novel technique was established to calculate the starting temperature of volatile emission in determining the volatile release parameter of foundry sand for cast iron. Foundry sand does not readily evaporate because its volatile content is only about 2.68 wt% and its main components have high-temperature stability. The thermal decomposition kinetics parameters of foundry sand, namely activation energy and pre-exponential factor, were obtained under kinetics theory. The activation energy of foundry sand for cast iron was small, mainly due to the wide temperature range of thermal decomposition in the foundry sand.

scholarly journals Study on Spacing Threshold of Nonsubmerged Spur Dikes with Alternate Layout

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Xiaomeng Cao ◽  
Zhenghua Gu ◽  
Hongwu Tang
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Empirical Formula ◽  
Multivariate Regression ◽  
Channel Width ◽  
Impact Scale ◽  
Calculation Results ◽  
Spur Dikes ◽  
Volume Method ◽  
The Impact

This paper investigated the spacing threshold of nonsubmerged spur dikes with alternate layout to classify the impact scale of spur dikes. A mathematical model was built based on standardk-εmodel, finite volume method (FVM), and rigid lid assumption and was verified by experimental data. According to dimensional analysis, three indices, that is,Fr(Froude number),B/b(channel width to dike length), andB/h(channel width to water depth), were identified as the influencing factors on the spacing threshold, based on which fifteen sets of conditions were simulated. The calculation results indicate thatB/his the most influencing parameter onSc/b(spacing threshold to dike length), followed byB/bandFr. A dimensionless empirical formula of spacing threshold is fitted by multivariate regression. The results of four sets of additional conditions illustrate that the generalization of empirical formula is satisfactory and the precision of interpolation is higher than that of extrapolation. Furthermore, the spacing threshold of alternate spur dikes is generally smaller than ipsilateral spur dikes.

Study on Thermal Decomposition Kinetics of Nano-Cr(OH)3 Powder

2014 ◽  
Vol 692 ◽  
pp. 377-380 ◽  
Author(s):  
Feng Pan ◽  
Zai Yuan Li ◽  
Chun Ji Li
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Shape Factor ◽  
Decomposition Analysis ◽  
Decomposition Kinetics ◽  
Peak Shape ◽  
Exponential Factor ◽  
Mechanism Function ◽  
Kinetics Of ◽  
Tga Analysis

Abstract. This paper studies on the thermal decomposition analysis kinetics of nanometer powders. The DTA-TG-DTG curves obtain by SDT 2960 Simultaneous DSC-TGA analysis apparatus. Under the condition of N2atmosphere operation and rise temperature velocity was 10°C·min-1. The mechanism function dα/dt=κ(1-α)nis used to calculate the kinetics factors. Reaction progressionnwas obtained by calculation of the kissinger peak shape factor method. The results showed that the apparent activation energy of nano-Ni(OH)2was 254.027 KJ·mol-1, the pre-exponential factor was 3.062×1036, the reaction progression was obtained as 1.560, the kinetic equation is dα/dt=3.062×1036exp(-30554.166/T)(1-α)1.560

scholarly journals DETERMINATION OF THERMAL DECOMPOSITION REACTION CHARACTERISTICS (A, E) OF WOOD SAMPLES FOR FIRE DYNAMICS SIMULATION

2013 ◽  
Vol 1 (2) ◽  
pp. 13-24 ◽  
Author(s):  
László Beda ◽  
Attila Szabó
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Decomposition Reaction ◽  
Dynamics Simulation ◽  
Fire Dynamics ◽  
Exponential Factor ◽  
Decomposition Reactions ◽  
Reaction Characteristics ◽  
Reaction Activation Energy

Abstract The purpose of this work is to determine the pre-exponential factor (A) and the reaction activation energy (E) of decomposition reactions that are needed for Fire Dynamics Simulation (FDS) using Derivatograph Q 1500D. The materials we investigated: Pine Wood Board (PWB), Multilayered Parquet Board (MPB), Particleboard Core (PBC) and Oriented Standard Board (OSB).

scholarly journals Thermal Decomposition of 3-Nitro-1,2,4-Triazole-5-One (NTO) and Nanosize NTO Catalyzed by NiFe2O4

2022 ◽  
Author(s):  
Pragnesh N. Dave ◽  
Ruksana Sirach ◽  
Riddhi Thakkar ◽  
Shalini Chaturvedi
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Catalytic Activity ◽  
Nickel Catalyst ◽  
Nickel Ferrite ◽  
Peak Temperature ◽  
Kinetics Parameters ◽  
Exponential Factor ◽  
Nanometer Size ◽  
Co Precipitation

Abstract Nanosize Nickel ferrite (NiF) was synthesized by the co-precipitation methods and its effect as a 5 % by mass additive was studied on the thermal decomposition of micrometer and nanometer size NTO. In the presence of 5 % NiF additive, the thermal decomposition peak temperature of NTO was decreased from 276.36 to 260.18 oC and that of nano NTO was decreased from 261.38 to 258.89 oC (β=10 oC min-1). The kinetics parameters confirms the catalytic activity of NiF for the thermal decomposition of NTO, and nNTO as the parameters such as activation energy (NTO=~25.45 % and nNTO=~45.94 % decrement), and pre-exponential factor (NTO=~21.94 % and nNTO=~43.12 % decrement) were decreased when 5 % NiF additive was added to NTO, and nNTO. The rate of the decomposition process was increased in the presence of 5 % NiF catalyst, indicating the faster thermal decomposition of both NTO, and nNTO in the presence of nickel catalyst.

Analyzing the discrepancies in the activation energies of the backbiting and β-scission reactions in the radical polymerization of n-butyl acrylate

2016 ◽  
Vol 7 (11) ◽  
pp. 2069-2077 ◽  
Author(s):  
S. Hamzehlou ◽  
N. Ballard ◽  
Y. Reyes ◽  
A. Aguirre ◽  
J. M. Asua ◽  
...  
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Mathematical Model ◽  
Radical Polymerization ◽  
Butyl Acrylate ◽  
Activation Energies

Activaton energies for backbiting and β-scission reactions for the polymerization of n-BA were determined by fitting experimental data to a mathematical model. The activation energy for backbiting was higher and that for β-scission lower than those accepted in the literature.

scholarly journals RESEARCH OF RESEARCH OF νt-92 TURBULENCE MODEL FOR CALCULATING AN AXISYMMETRIC SOUND JET

2020 ◽  
Vol 4 (2) ◽  
pp. 82-90
Author(s):  
Murodil Erkinjon oglu Madaliev ◽  
◽  
Dilshod Primkulovich Navruzov
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Comparative Analysis ◽  
Turbulence Model ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Calculation Results ◽  
The One ◽  
Subsonic Jet

A comparative analysis of the use of the turbulence model is carried out: the one-parameter Secundov νt-92 model on the problem of an axisymmetric subsonic jet. The calculation results are compared with experimental results on the propagation of speed, voltage, and temperature. The flow is turbulent, therefore, as a mathematical model, the system of Navier-Stokes equations averaged by Reynolds (RANS) is used. For the posed problem, a generalized stream function ψ is introduced. A comparison was made of the results of the νt-92 model with experimental data from [5] the dimensionless axial velocity from the distance to the nozzle

scholarly journals Developing the operating principle and mathematical model of the downhole device for injecting scCO2 in productive formations

2021 ◽  
Vol 2057 (1) ◽  
pp. 012131
Author(s):  
P L Pavlova ◽  
D V Guzei
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Heat Flux ◽  
Temperature Distribution ◽  
Supercritical Fluids ◽  
Channel Wall ◽  
Heavy Oils ◽  
Calculation Results ◽  
Traditional Technologies ◽  
The Mathematical Model

Abstract Traditional technologies are not economically efficient in term of processing heavy and extra-heavy oils. Technologies based on the use of supercritical fluids (SCF) may become one of the innovative directions in the production and processing of heavy and extra-heavy oils. Therefore, in this paper the operation principle of the downhole device for pumping scCO2 into a productive reservoir is developed. The mathematical model is developed either. Calculations with different heat flux densities on the channel wall are carried out. The dependences of the temperature distribution along the length of the heated section are obtained. The calculation results are compared with experimental data.

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