Kinetics of crystallization in amorphous Se73.2Te21.1Sb5.7 under isochronal conditions: Effect of heating rate on the activation energy

2007 ◽  
Vol 390 (1-2) ◽  
pp. 196-202 ◽  
Author(s):  
A.A. Abu-Sehly ◽  
A.A. Elabbar
Keyword(s):  
Activation Energy ◽  
Heating Rate ◽  
Kinetics Of Crystallization ◽  
Kinetics Of

Research on Pyrolysis Kinetics of Shenhua Coal and Direct Liquefaction Residue

2012 ◽  
Vol 550-553 ◽  
pp. 2758-2762 ◽  
Author(s):  
Xi Jie Chu ◽  
Yong Gang Wang ◽  
Li Hong Zhao
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Kinetic Parameters ◽  
Heating Rate ◽  
Coal Pyrolysis ◽  
Pyrolysis Kinetics ◽  
Differential Heating ◽  
Pyrolysis Behavior ◽  
Direct Liquefaction ◽  
Kinetics Of

The pyrolysis tests of Shenhua coal and Shenhua direct liquefaction residue have been carried out using thermogravimetric at the differential heating rate. The kinetic parameters k and E were calculated using DAEM method. Results show DAME model can describe the pyrolysis behavior of Shenhua coal within the range of 20% to 95%, the activation energy of coal pyrolysis ranges from 53.98 to 279.38 kJ/mol, and DAME model can describe the behavior of Shenhua direct liquefaction residue within the range of 10% to 80%, the activation energy of residue pyrolysis is about 170 kJ/mol. The results of which are basically consistent with the experimental data.

Microcalorimetry and Kinetics of Biodiesel

2014 ◽  
Vol 592-594 ◽  
pp. 1647-1651
Author(s):  
S.P. Sivapirakasham ◽  
A. Afsal Khan ◽  
Mane G. Yogesh ◽  
R. Anand
Keyword(s):  
Activation Energy ◽  
Kinetic Model ◽  
Heating Rate ◽  
Diesel Fuel ◽  
Fossil Fuel ◽  
Uniform Heating ◽  
Nitrogen Gas ◽  
Gas Atmosphere ◽  
Great Acceptance ◽  
Kinetics Of

Now a day biodiesel becomes best alternative for diesel fuel. Thermogravimetry technique has great acceptance in the field of fossil fuel. The thermal and kinetics properties of diesel and Jatropha biodiesel are analyzed by using popular technique of thermogravimetry. The aim is to study the behavior of diesel, biodiesel and their blends in Nitrogen gas atmosphere at the heating rate of 5K/min, 10K/min and 15K/min from 30°C to 600°C. From study it is found that as heating rate increases peak is shifting toward higher value which shows that there is less uniform heating. The study clearly shows biodiesel is more stable than diesel indicating that transesterification make sample less stable. The Arrehenius Kinetic model is applied to study the activation energy. As percentage of biodiesel increases, stability of sample increases and hence increases in activation energy

scholarly journals Kinetics of crystallization of Ge30-xSe70Sbx (x=15, 20, 25) chalcogenide glasses

2014 ◽  
Vol 8 (1) ◽  
pp. 25-30 ◽  
Author(s):  
Anusaiya Kaswan ◽  
Vandana Kumari ◽  
Dinesh Patidar ◽  
Narendra Saxena ◽  
Kananbala Sharma
Keyword(s):  
Activation Energy ◽  
Energy Barrier ◽  
Chalcogenide Glasses ◽  
Frequency Factor ◽  
Heating Rates ◽  
Kinetics Of Crystallization ◽  
Theoretical Approaches ◽  
Activation Energy Of Crystallization ◽  
Ozawa Model ◽  
Kinetics Of

The kinetics of crystallization of Ge30-xSe70Sbx (x=15, 20, 25) chalcogenide glasses has been investigated using differential scanning calorimetery at different heating rates under non-isothermal conditions. The kinetic analysis of crystallization has been discussed using different theoretical approaches such as Ozawa model, Augis and Bennet model, Matusita model and Gao-Wang model. It is evident from this study that the activation energy of crystallization Ec is composition dependent. The activation energy decreases with increasing Sb content due to the increasing of rate of crystallization. The minimum value of the frequency factor Ko, which is defined as the number of attempts made by the nuclei per second to overcome the energy barrier, confirms the fact that glass is more stable. It has been found that Ge15Se70Sb15 glass is more stable compared to the other compositions.

Generalised kinetics of overall phase transition useful for glass crystallisation when assuming non-isothermal conditions

2020 ◽  
Vol 61 (6) ◽  
pp. 209-212 ◽  
Author(s):  
Isak Avramov ◽  
◽  
Jaroslav Šesták ◽  
Keyword(s):  
Experimental Data ◽  
Phase Transition ◽  
Activation Energy ◽  
Heating Rate ◽  
Characteristic Temperature ◽  
Isothermal Conditions ◽  
Constant Rate ◽  
Avrami Parameter ◽  
Kinetics Of ◽  
Glass Crystallisation

The modelling of reaction kinetics is a fashionable subject of publications. We developed an analogue of the KJMA equation under non-isothermal conditions α(T)=1−exp(−(T/θ)N) that describes the dependence of degree of transformation α(T) at a constant rate, q, of heating with characteristic temperature θ(q) and power N, proportional to the Avrami parameter, n. This equation is valid even when the activation energy of the process is not constant. We demonstrate that reliable information about the activation energy is obtained when the experimental data are plotted in coordinates: logq (heating rate) against logTp (peak temperature).

Thermo-Gravimetric Analysis and Kinetic Study of Biomass Pyrolysis

2013 ◽  
Vol 800 ◽  
pp. 509-516 ◽  
Author(s):  
Yong Sheng Fan ◽  
Xiao Hua Li ◽  
Yi Xi Cai ◽  
Wei Dong Zhao ◽  
Hai Yun Yin
Keyword(s):  
Activation Energy ◽  
Heating Rate ◽  
Thermo Gravimetric Analysis ◽  
Evaluation Methodology ◽  
Gravimetric Analysis ◽  
Pyrolysis Process ◽  
Biomass Pyrolysis ◽  
Thermo Gravimetric ◽  
Exponential Factor ◽  
Kinetics Of

In order to realize the optimization of pyrolysis process, the pyrolysis characteristics and kinetics of common agriculture and forestry biomass were studied. Four kinds of biomass were chosen as experiment materials for thermo-gravimetric experiment. The Characteristics of biomass pyrolysis was studied by defining a new evaluation methodology. The method of Coats-Redfern was used to analyze pyrolysis kinetics of biomass pyrolysis process. The results of research show that the pyrolysis process of biomass can be divided into three stages, including drying and preheating, fast pyrolysis and slow decomposition of residue. The activation energy of pyrolysis reaction of biomass during the low temperature stage is higher than that of the high temperature stage. The values of the activation energy and pre-exponential factor are increasing with the increase of heating rate. The pyrolysis of biomass in the main pyrolysis zone can be effectively described by using the kinetic model n=2. The heating rate of 15K/min and temperature of 500°C can improve the reaction rate, and it helps to reduce energy consumption of the reaction.

Layer by Layer Amorphization in Si: Temperature, Ion Mass and Flux Effects

1993 ◽  
Vol 321 ◽  
Author(s):  
A. Battaglia ◽  
G. Romano ◽  
S. U. Campisano
Keyword(s):  
Activation Energy ◽  
Substrate Temperature ◽  
Apparent Activation Energy ◽  
Phenomenological Model ◽  
Ion Flux ◽  
Experimental Results ◽  
Layer By Layer ◽  
Kinetics Of Crystallization ◽  
Temperature Range ◽  
Kinetics Of

ABSTRACTThe layer-by-layer amorphization process is explored in a temperature range in which the kinetics of crystallization can be neglected. It has been found that the pure amorphization rate increases exponentially as the substrate temperature is decreased with an apparent activation energy of 0.48 eV. Moreover the rate increases with both the ion flux and the energy deposited into elastic collisions. A phenomenological model is proposed to explain the experimental results.

Layer by Layer Amorphization in Si: Temperature, Ion Mass and Flux Effects

1993 ◽  
Vol 316 ◽  
Author(s):  
A. Battaglia ◽  
G. Romano ◽  
S.U. Campisano
Keyword(s):  
Activation Energy ◽  
Substrate Temperature ◽  
Apparent Activation Energy ◽  
Phenomenological Model ◽  
Ion Flux ◽  
Experimental Results ◽  
Layer By Layer ◽  
Kinetics Of Crystallization ◽  
Temperature Range ◽  
Kinetics Of

ABSTRACTThe layer-by-layer amorphization process is explored in a temperature range in which the kinetics of crystallization can be neglected. It has been found that the pure amorphization rate increases exponentially as the substrate temperature is decreased with an apparent activation energy of 0.48 eV. Moreover the rate increases with both the ion flux and the energy deposited into elastic collisions. A phenomenological model is proposed to explain the experimental results.

scholarly journals Study on reaction kinetics of single slime

2021 ◽  
Vol 236 ◽  
pp. 02012
Author(s):  
Kun Zhou ◽  
Wei Fu ◽  
Hongxi Xie ◽  
Jihu Bao ◽  
Yayun Li ◽  
...  
Keyword(s):  
Activation Energy ◽  
Kinetic Parameters ◽  
Heating Rate ◽  
Integration Method ◽  
Ash Content ◽  
Solid Fuels ◽  
Coal Slime ◽  
Reaction Activation Energy ◽  
Kinetics Of ◽  
Combustion Of Solid Fuels

The study of the combustion characteristics of single slime fuels is the basis for achieving clean combustion of solid fuels. This paper uses a combination of experimental and theoretical analysis, combined with the Coats-Redfen integration method, to study the influence of ash content and heating rate on the kinetic parameters of coal slime, and solve the combustion kinetic parameters. The results show that under the same heating rate, the activation energy gradually increases. As the ash content of coal slime increases, the activity of the coal slime sample decreases, and the reaction activation energy gradually increases.

scholarly journals Pyrolysis Reactive Behaviors and Kinetic Characteristics of HSW Vitrinite Coal based on Coats-Redfern and DAEM Models

2021 ◽  
Author(s):  
Ruihan Wang ◽  
Qiang Wang ◽  
Zhuangmei Li ◽  
Zhe Liu ◽  
Yong Wu ◽  
...  
Keyword(s):  
Activation Energy ◽  
Weight Loss ◽  
Heating Rate ◽  
Loss Rate ◽  
Coal Tar ◽  
Coal Pyrolysis ◽  
Heating Rates ◽  
Weight Loss Rate ◽  
Weight Loss Behavior ◽  
Kinetics Of

Abstract In this work, the weight loss behavior of vitrinite in hongshiwan coal at different heating rates was investigated by thermogravimetric mass spectrometry (TG-MS). Then Coats-Redfern and DAEM models were established to analyze the kinetics of coal pyrolysis. The results show that the weight loss rate of pyrolysis decreased with the increase of heating rate. When the pyrolysis temperature reaches 400–500°C, the weight loss rate reaches the maximum, which is 0.1593, 0.1539, 0.1478 and 0.1414%/°C respectively at the heating rates of 5, 10, 15 and 20°C/min, With the increase of heating rate, the corresponding temperature peaks of the five pyrolysis gases are shifted to the high temperature direction, and the amount of gas escaping is increasing. The trend of higher heating rate delayed the release of volatile compounds was consistent with TG-DTG results. Two kinetic models both prove that the activation energy of coal pyrolysis increases with the increase of temperature. The maximum activation energy occurs between 600 ℃ and 900 ℃, because the multi condensation of coal tar and the re solidification of semi coke will occur in this temperature range.

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