The Determination of Kinetic Parameters of Transformer Oil and its Blends by Thermal Analysis

2012 ◽  
Vol 13 (4) ◽  
Author(s):  
Veresha Dukhi ◽  
Ajay Bissessur ◽  
Catherine Jane Ngila ◽  
Nelson Mutatina Ijumba
Keyword(s):  
Activation Energy ◽  
Weight Loss ◽  
Kinetic Parameters ◽  
Breakdown Voltage ◽  
Activation Energies ◽  
Transformer Oil ◽  
Dielectric Fluid ◽  
Differential Scanning Calorimetric ◽  
Significant Difference

Abstract The insulation of transformer oil comprise of two practices: paper and dielectric fluid (such as mineral transformer oil). Ageing of these oils occur mainly by thermal, electrical and oxidative stresses. This paper describes the determination of kinetic parameters of a naphthenic based transformer oil and its blends based on the Ozawa, Flynn and Wall (OFW) and Kissinger models using data obtained from thermogravimetric analysis (TGA) and differential scanning calorimetric (DSC), plots. Virgin oil and its blends were analysed from an initial temperature range of 20-25 ºC to 300 ºC at temperature ramps of 1, 2, 4, 6, 8 and 10 ºC min-1. The OFW method in conjunction with TGA data was used to calculate the apparent decomposition activation energies at each of the selected weight loss (% conversion or α) values. The activation energies at 10% weight loss were found to be 57.0, 63.7 and 69.3 kJ mol-1 for BHT-B (virgin oil-2,6-di-tert-butyl-4-methylphenol blends), DBP-B (virgin oil-2,6-di-tert-butylphenol blends) and VO (virgin transformer oil), respectively. However using this method the activation energy (Ea) of the oils showed no significant difference between virgin oil and its blends. DSC curves revealed that the decomposition reaction was exothermic in nature. From DSC data the activation energy was determined using two separate models: OFW and Kissinger models. Decomposition activation energy obtained from DSC data showed no significant difference when applied to these two models. Dissipation factor tests showed superior results for the blends when compared to those of virgin transformer oil. However, the blends showed substantial reductions in their dielectric breakdown voltage. The implication of the reduced breakdown voltage is that the blends show poorer dielectric strength in comparison to virgin transformer oil.

The Determination of Kinetic Parameters of Transformer Oil and its Blends by Thermal Analysis

ENERGYO ◽  
2018 ◽  
Author(s):  
Veresha Dukhi ◽  
Ajay Bissessur ◽  
Catherine Jane Ngila ◽  
Nelson Mutatina Ijumba
Keyword(s):  
Thermal Analysis ◽  
Kinetic Parameters ◽  
Transformer Oil

Thermal Cure and Ceramization Kinetics of Perhydropolysilazane

2013 ◽  
Vol 575-576 ◽  
pp. 81-86 ◽  
Author(s):  
Feng Ling Ma ◽  
Hui Min Qi ◽  
Ya Ping Zhu ◽  
Xiao Wen Ren ◽  
Fan Wang
Keyword(s):  
Activation Energy ◽  
Weight Loss ◽  
Thermogravimetric Analysis ◽  
Kinetic Parameters ◽  
Nitrogen Atmosphere ◽  
Thermal Cure ◽  
Exponential Factor ◽  
Kinetics Of

The kinetics of the thermal cure and ceramization of preceramic prehydropolysilazane (PHPS) was investigated by thermogravimetric analysis (TGA) under nitrogen atmosphere. The results indicated that the gases captured during the thermal cure and ceramization process of PHPS, which had three main weight loss events. The corresponding kinetic parameters including activation energy, pre-exponential factor and empirical order of the thermal cure and ceramization stages were evaluated by using Ozawa and Kissinger metnods, respectively.

Application of non-linear heating regime for the determination of activation energy and kinetic parameters of solid-state reactions

1998 ◽  
Vol 323 (1-2) ◽  
pp. 101-107 ◽  
Author(s):  
K.V Tomashevitch ◽  
S.V Kalinin ◽  
A.A Vertegel ◽  
N.N Oleinikov ◽  
V.A Ketsko ◽  
...  
Keyword(s):  
Activation Energy ◽  
Solid State ◽  
Kinetic Parameters ◽  
Solid State Reactions ◽  
Heating Regime ◽  
Linear Heating ◽  
Non Linear

Determination of Activation Energy of the Iron Acceptor Pair Association and Dissociation Reaction

2015 ◽  
Vol 242 ◽  
pp. 230-235
Author(s):  
Kevin Lauer ◽  
Christian Möller ◽  
D. Debbih ◽  
Manuel Auge ◽  
Dirk Schulze
Keyword(s):  
Activation Energy ◽  
Iron Content ◽  
Reaction Rates ◽  
Activation Energies ◽  
Illumination Intensity ◽  
Dissociation Reaction ◽  
Acceptor Pair ◽  
Association Reaction

A method to measure the reaction rates of the iron acceptor pair association and dissociation is presented and applied. The activation energies of the dissociation and association reaction are determined for the acceptors boron, aluminum, gallium and indium. Additionally, the activation energies are reported for different illumination intensities. It is found that the activation energy of the association reaction varies for the investigated acceptors and that the activation energy of the dissociation reaction depends strongly on the illumination intensity. It is shown that neglecting of the dissociation reaction in the evaluation of relative interstitial iron content decrease causes a considerable overestimation of the activation energy of the iron acceptor association.

Thermal Decomposition of Phosphate Ore by Using Differential Scanning Calorimetric Method

2014 ◽  
Vol 887-888 ◽  
pp. 1005-1009
Author(s):  
Lin Zhuan Ma ◽  
Chao Huang ◽  
Jun Ming Guo ◽  
Zhi Ying Wang
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Weight Loss ◽  
Loss Rate ◽  
Decomposition Process ◽  
Differential Scanning Calorimetric ◽  
Heating Rates ◽  
Thermal Decomposition Process ◽  
Phosphate Ore ◽  
Dsc Curves

Phosphate ore was decomposed by using thermogravimetric (TG) and differential scanning calorimetric (DSC). The TG-DSC curves contained different sizes and heating rates. The results showed that phosphate ore had four weight loss stages at the range of 40 ~ 1100°C. With the particle size decreasing, the third weight loss stage became more obvious in TG curves and the endothermic peak became sharper in DSC curve ; the starting and ending temperature of thermal decomposition process moved to higher,the weight loss rate also tended to increase; the activation energy of phosphate ore endothermic decomposition process was calculated by Owaza method in 600~800°C, the average activation energy was 202.80 kJ / mol. It provided a basis for the utilizing of phosphate ore.

scholarly journals Kinetics of the oxidation reactions and decomposition of pyrite

Cerâmica ◽  
2017 ◽  
Vol 63 (365) ◽  
pp. 39-43 ◽  
Author(s):  
P. H. Concer ◽  
C. M. de Oliveira ◽  
O. R. K. Montedo ◽  
E. Angioletto ◽  
M. Peterson ◽  
...  
Keyword(s):  
Activation Energy ◽  
Weight Loss ◽  
Mining Industry ◽  
Activation Energies ◽  
Parameter Determination ◽  
Heating Rates ◽  
So2 Emissions ◽  
Exponential Factor ◽  
Decomposition Reactions ◽  
Friedman Method

Abstract Despite the great abundance of pyrite in nature and its role as one of the main sources of SO2 emissions in industrial processes, there is little definitive information about the kinetics and mechanisms of pyrite oxidation and decomposition reactions. This work aimed to determine the viability of applying the Friedman method for kinetic parameter determination to the oxidation and decomposition reactions of pyrite from the coal mining industry in order to obtain pyrite-based magnetic materials. Such method is based on the use of experimental weight loss data obtained using thermogravimetric analysis (TG) for the determination of the reaction activation energies. Thus, the activation energy, the pre-exponential factor and the reaction order were obtained using TG curves with different heating rates (2.5, 5.0, 7.5 and 10.0 K.min-1). For inert atmosphere, the calculated activation energies of approximately 280 kJ.mol-1 agree with the literature values. The reaction in oxidant atmosphere showed two predominant weight loss regions, suggesting the existence of two different reactions. The 482 kJ.mol-1 value obtained for the activation energy of the second weight loss that occurred at approximately 770 K was similar to the results reported by other authors. For the observed weight loss at approximately 650 K, similar values were not found in the literature to compare to the results of the Friedman method. The theoretical activation energy was therefore determined with empirical equations. A theoretical value of approximately 1000 kJ.mol-1 was obtained for the decomposition of pyrrhotite. The values found for the other kinetic parameters showed inconsistencies.

Activation Energy and NBO Interaction Approaches to the Determination of the Relative Resonance Acceptor Strengths of CN, NO, COMe, CHO and NO2 Groups from the Ring-Opening of 1,2-Benzo-3-Carbomethoxycyclobutenes

2019 ◽  
Author(s):  
Veejendra Yadav ◽  
Arpita Yadav
Keyword(s):  
Activation Energy ◽  
Interaction Energy ◽  
Ring Opening ◽  
Activation Energies ◽  
Interaction Energies ◽  
Differential Activation ◽  
Transition Structures

<p>The relative resonance-acceptor ability based on the activation energies for the outward ring-openings of 1,2-benzo-3-carbomethoxycyclobutenes bearing CN, NO, COMe, CHO and NO<sub>2</sub> as C6 and C7 substituents is different from that based on the s<sub>C3C4</sub>-p*<sub>C1C2</sub> interactions in the inward opening transition structures. The differential activation energy (∆G<sup>‡</sup>) predicts outward ring-opening and, in contrast, the differential s<sub>C3C4</sub>-p*<sub>C1C2</sub> interaction energy predicts inward opening, throughout. The relative resonance-acceptor ability estimated from the s<sub>C3C4</sub>-p*<sub>C1C2</sub> interaction energies is more realistic than that from the activation energies.</p>

scholarly journals Assay of β-N-acetylhexosaminidase isoenzymes in different biological specimens by means of determination of their activation energies

1998 ◽  
Vol 44 (2) ◽  
pp. 226-231 ◽  
Author(s):  
Luis F Pérez ◽  
J Carlos Tutor
Keyword(s):  
Activation Energy ◽  
Cerebrospinal Fluid ◽  
Catalytic Activity ◽  
Seminal Plasma ◽  
Activation Energies ◽  
Thermodynamic Method ◽  
Heat Inactivation ◽  
Specific Substrate ◽  
Isoenzyme Composition

Abstract The activation energy (Ea) of β-N-acetylhexosaminidase (Hex, EC 3.2.1.52) was determined with 3,3′-dichlorophenylsulfonphthaleinyl-N-acetyl-β-d-glucosaminide as substrate, with a much higher value being found for the Hex B isoenzyme (Ea = 75.1 kJ/mol) than for the Hex A isoenzyme (Ea = 41.8 kJ/mol). This fact allowed for the development of a fast and reliable thermodynamic method to determine the isoenzyme composition of Hex in different biological specimens (serum/plasma, saliva, cerebrospinal fluid, seminal plasma, urine, and leukocyte lysates). The results in serum given by the proposed method may be superimposed upon those obtained by the heat inactivation assay of O’Brien et al. (N Engl J Med 1970;273:15–20), and the catalytic activity calculated for Hex A offers a good correlation with that obtained by using the specific substrate 4-methylumbelliferyl-N-acetyl-β-d-glucosaminide-6 sulfate (n = 25, r = 0.953).

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