scholarly journals Not Reacted Core Model Applied in Palm Nut Shell Pyrolysis

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Ernesto de la Torre ◽  
Sebastián Gámez
Keyword(s):  
Kinetic Parameters ◽  
Elaeis Guineensis ◽  
Effective Diffusion ◽  
Reaction Rate Constant ◽  
Core Model ◽  
Scanning Calorimetry ◽  
Differential Scanning Calorimetry Study ◽  
Different Temperatures ◽  
Char Conversion ◽  
Pyrolysis Of Biomass

One of the main sources of activated carbon is biomass which can be transformed into char by pyrolysis. Apart from the obtaining coal, the pyrolysis of biomass can be used for the preparation of fuels, and this is why it is very important to determine its kinetic parameters for modelling. In the present research, the pyrolysis enthalpy of palm nut shells (Elaeis guineensis) was determined with the use of a differential scanning calorimetry study (DSC). To determine the kinetic parameters, the Not Reacted Core model was employed. This model considers that there is a heat and mass gradient between the furnace atmosphere and the interface formed during pyrolysis. To obtain the required data for the model, palm nut shells were submitted to pyrolysis in a Nichols furnace under reducing atmosphere. Samples were taken every 10 minutes to calculate char conversion. The experimental pyrolysis enthalpy resulted to be 301.81 J/g and then the monomeric units of cellulose, hemicellulose, and lignin were employed in order to determine the pyrolysis enthalpy per mole. The three biopolymers react with different mechanisms at different temperatures. The molecular weight resulted to be 172.38 g/mole, and the enthalpy for pyrolysis was 52.03 kJ/mol. For the application of the Not Reacted Core model, the amorphous char heat transfer coefficient was selected, and the value is 1.6 J/s·m·K. The reaction rate constant was 6.64 × 10−9 1/s assuming a first-order reaction, whereas the effective diffusion across the char layer was 4.83 × 10−7 m2/s.

Kinetics Analysis of Direct Nitridation of Silicon Powders at Atmospheric Pressure

2012 ◽  
Vol 562-564 ◽  
pp. 167-170 ◽  
Author(s):  
Shao Wu Yin ◽  
Li Wang ◽  
Li Ge Tong ◽  
Fu Ming Yang ◽  
Yan Hui Li
Keyword(s):  
Atmospheric Pressure ◽  
Conversion Rate ◽  
Effective Diffusion ◽  
Silicon Powder ◽  
Reaction Rate Constant ◽  
Kinetics Parameters ◽  
Exponential Factor ◽  
Different Temperatures ◽  
Shrinking Core ◽  
Direct Nitridation

Silicon nitride powders were prepared via direct nitridation of silicon powders diluted with -Si3N4at atmospheric pressure. The nitridation temperature and time were ranged from1623K to 1823K and from 0 minute to 20 minutes respectively. Based on the relations between the conversion rate of silicon and the time at different temperatures, and using shrinking core model, a simple model for the reaction between silicon and nitrogen was derived. The model showed that the relations between the conversion rate of silicon and the time displayed asymptotic exponential conversion trend. Using this model, the kinetics parameters of nitridation of silicon powder at atmospheric pressure were calculated, including pre-exponential factor in Arrhenius equation, activation energy, effective diffusion coefficient, and the formula of the reaction rate constant.

Study on Thermal Degradation Characteristics of Pre-Treated Paraffin

2014 ◽  
Vol 496-500 ◽  
pp. 246-250
Author(s):  
Song Qi Hu ◽  
Guan Jie Wu
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermal Degradation ◽  
Heat Release ◽  
Kinetic Parameters ◽  
Decomposition Temperature ◽  
Exothermic Peak ◽  
Initial Reaction ◽  
Scanning Calorimetry ◽  
Reaction Heat ◽  
Different Temperatures

The paraffin, pre-treated paraffin and hydroxyl-terminated polybutadiene (HTPB) were measured by Differential Scanning Calorimetry (DSC) and Thermogravimetry (TG) in different conditions. Thermal degradation characteristics of the paraffin, pre-treated paraffin and HTPB were studied; Influences of different pressure and different temperatures on thermal degradation characteristics of pre-treated paraffin were analyzed. Experiments show that the decomposition temperature of pre-treated paraffin is higher than that of the untreated paraffin, but lower than that of HTPB; the initial reaction temperature, the reaction exothermic peak temperature and the reaction heat release of pre-treated paraffin were all affected by pressure and heating rate; Kinetic parameters of pre-treated paraffin in oxygen atmosphere were calculated.

Effects of additives on the cure kinetics of vinyl ester pultrusion resins

2021 ◽  
pp. 002199832110015
Author(s):  
Alexander Vedernikov ◽  
Yaroslav Nasonov ◽  
Roman Korotkov ◽  
Sergey Gusev ◽  
Iskander Akhatov ◽  
...  
Keyword(s):  
Vinyl Ester ◽  
Mean Squared Error ◽  
Cure Kinetics ◽  
Zinc Stearate ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Different Temperatures ◽  
Predicted Values ◽  
Kinetics Of ◽  
Final Degree

Pultrusion is a highly efficient composite manufacturing process. To accurately describe pultrusion, an appropriate model of resin cure kinetics is required. In this study, we investigated cure kinetics modeling of a vinyl ester pultrusion resin (Atlac 430) in the presence of aluminum hydroxide (Al(OH)3) and zinc stearate (Zn(C18H35O2)2) as processing additives. Herein, four different resin compositions were studied: neat resin composition, composition with Al(OH)3, composition comprising Zn(C18H35O2)2, and composition containing both Al(OH)3 and Zn(C18H35O2)2. To analyze each composition, we performed differential scanning calorimetry at the heating rates of 5, 7.5, and 10 K/min. To characterize the cure kinetics of Atlac 430, 16 kinetic models were tested, and their performances were compared. The model based on the [Formula: see text]th-order autocatalytic reaction demonstrated the best results, with a 4.5% mean squared error (MSE) between the experimental and predicted data. This study proposes a method to reduce the MSE resulting from the simultaneous melting of Zn(C18H35O2)2. We were able to reduce the MSE by approximately 34%. Numerical simulations conducted at different temperatures and pulling speeds demonstrated a significant influence of resin composition on the pultrusion of a flat laminate profile. Simulation results obtained for the 600 mm long die block at different die temperatures (115, 120, 125, and 130 °C) showed that for a resin with a final degree of cure exceeding 95% at the die exit, the maximum difference between the predicted values of pulling speed for a specified set of compositions may exceed 1.7 times.

scholarly journals Quantitative Comparison of Binary Mix of Agro-Industrial Pozzolanic Additions for Elaborating Ternary Cements: Kinetic Parameters

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2944
Author(s):  
Ernesto Villar-Cociña ◽  
Moisés Frías ◽  
Holmer Savastano ◽  
Loic Rodier ◽  
María Isabel Sánchez de Rojas ◽  
...  
Keyword(s):  
Kinetic Parameters ◽  
Sugar Cane ◽  
Research Work ◽  
Pozzolanic Reaction ◽  
Reaction Rate Constant ◽  
Pozzolanic Activity ◽  
Binary Blend ◽  
Activation Free Energy ◽  
Pozzolanic Reactivity ◽  
Bamboo Leaf Ash

In this research work, the quantitative characterization of a binary blend comprised of two pozzolans (sugar cane straw (SCSA)–sugar cane bagasse ashes (SCBA), bamboo leaf ash (BLAsh)–SCBA and paper sludge (PS)–fly ash (FA)) taking into account the calculated values of the kinetic parameters of the reaction in the pozzolan/calcium hydroxide system is shown. The paper shows the most significant and important results obtained by the authors in the quantitative assessment (calculation of kinetic parameters) of the pozzolanic reaction of different mixtures of pozzolanic materials that are residues from agriculture or industrial processes. This allows a direct and rigorous comparison of the pozzolanic activity of the binary combinations of materials. The values of the kinetic parameters (reaction rate constant or activation free energy) constitute a very precise quantitative index of the pozzolanic activity of the binary combinations of materials, which is very useful for its employment in the elaboration of ternary cements. This paper shows that the binary blends 1SCBA60Blash40, 1SCBA50Blash50, 1SCBA70Blash30 have a very high pozzolanic reactivity followed by PSLSFA, 2SCBA50SCSA50, PSISFA and SCWI.

scholarly journals Kinetics and thermodynamic properties related to the drying of 'Cabacinha' pepper fruits

2016 ◽  
Vol 20 (2) ◽  
pp. 174-180 ◽  
Author(s):  
Hellismar W. da Silva ◽  
Renato S. Rodovalho ◽  
Marya F. Velasco ◽  
Camila F. Silva ◽  
Luís S. R. Vale
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Free Energy ◽  
Thermodynamic Properties ◽  
Gibbs Free Energy ◽  
Removal Rate ◽  
Effective Diffusion ◽  
Drying Time ◽  
Three Samples ◽  
Different Temperatures

ABSTRACT The objective of this study was to determine and model the drying kinetics of 'Cabacinha' pepper fruits at different temperatures of the drying air, as well as obtain the thermodynamic properties involved in the drying process of the product. Drying was carried out under controlled conductions of temperature (60, 70, 80, 90 and 100 °C) using three samples of 130 g of fruit, which were weighed periodically until constant mass. The experimental data were adjusted to different mathematical models often used in the representation of fruit drying. Effective diffusion coefficients, calculated from the mathematical model of liquid diffusion, were used to obtain activation energy, enthalpy, entropy and Gibbs free energy. The Midilli model showed the best fit to the experimental data of drying of 'Cabacinha' pepper fruits. The increase in drying temperature promoted an increase in water removal rate, effective diffusion coefficient and Gibbs free energy, besides a reduction in fruit drying time and in the values of entropy and enthalpy. The activation energy for the drying of pepper fruits was 36.09 kJ mol-1.

scholarly journals Superior Degradation Performance of Nanoporous Copper Catalysts on Methyl Orange

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 913
Author(s):  
Jinyi Wang ◽  
Sen Yang
Keyword(s):  
Activation Energy ◽  
Methyl Orange ◽  
High Efficiency ◽  
Low Cost ◽  
Degradation Process ◽  
Copper Catalysts ◽  
Reaction Rate Constant ◽  
Nanoporous Structure ◽  
Intra Particle Diffusion ◽  
Different Temperatures

The development of low-cost and high-efficiency catalysts for wastewater treatment is of great significance. Herein, nanoporous Cu/Cu2O catalysts were synthesized from MnCu, MnCuNi, and MnCuAl with similar ligament size through one-step dealloying. Meanwhile, the comparisons of three catalysts in performing methyl orange degradation were investigated. One of the catalysts possessed a degradation efficiency as high as 7.67 mg·g−1·min−1. With good linear fitting by the pseudo-first-order model, the reaction rate constant was evaluated. In order to better understand the degradation process, the adsorption behavior was considered, and it was divided into three stages based on the intra-particle diffusion model. Three different temperatures were applied to explore the activation energy of the degradation. As a photocatalytic agent, the nanoporous structure of Cu/Cu2O possessed a large surface area and it also had low activation energy, which were beneficial to the excellent degradation performance.

Estimation of Firing Temperature and Compositional Variability of Archaeological Pottery by Differential Scanning Calorimetry

2004 ◽  
Vol 852 ◽  
Author(s):  
A. Giordana ◽  
E. Peacock ◽  
M. McCarthy ◽  
K. Guilbeau ◽  
P. Jacobs ◽  
...  
Keyword(s):  
Firing Temperature ◽  
Thermal Characterization ◽  
Small Sample ◽  
Scanning Calorimetry ◽  
Blind Test ◽  
Vitrification Temperature ◽  
Archaeological Pottery ◽  
Digital Scanning ◽  
Different Temperatures ◽  
Upper Estimate

ABSTRACTDigital Scanning Calorimetry (DSC), a thermal characterization technique, can be used to rapidly obtain a rough upper estimate of the firing temperature of archaeological pottery as well as an indication of its composition. The technique involves heating a small sample (10–20 mg) of ground ceramic above the vitrification temperature, cooling and reheating. The curves of the two heating cycles are then compared. The validity of the technique was evaluated by a blind test in which 35 tiles fired at different temperatures were analyzed without knowing their firing point, and by analysis of archaeological pottery samples assumed to be local or imported based upon stylistic criteria.

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