Improving the Quantitative Description of Reacting Porous Solids: Critical Analysis of the Shrinking Core Model by Comparison to the Generalized Grain Model

2013 ◽  
Vol 53 (22) ◽  
pp. 8980-8995 ◽  
Author(s):  
Tommaso Melchiori ◽  
Paolo Canu
Keyword(s):  
Critical Analysis ◽  
Quantitative Description ◽  
Core Model ◽  
Porous Solids ◽  
Shrinking Core Model ◽  
Shrinking Core ◽  
Grain Model

CFD Simulation of Entrained Flow Gasification With Improved Devolatilization and Char Consumption Submodels

2009 ◽  
Author(s):  
Mayank Kumar ◽  
Cheng Zhang ◽  
Rory F. D. Monaghan ◽  
Simcha L. Singer ◽  
Ahmed F. Ghoniem
Keyword(s):  
Cfd Simulation ◽  
Quantitative Description ◽  
Core Model ◽  
Diffusion Control ◽  
Shrinking Core Model ◽  
Carbon Conversion ◽  
Pore Model ◽  
Shrinking Core ◽  
The Impact ◽  
Random Pore Model

In this work, we use a CFD package to model the operation of a coal gasifier with the objective of assessing the impact of devolatilization and char consumption models on the accuracy of the results. Devolatilization is modeled using the Chemical Percolation Devolitilization (CPD) model. The traditional CPD models predict the rate and the amount of volatiles released but not their species composition. We show that the knowledge of devolatilization rates is not sufficient for the accurate prediction of char consumption and a quantitative description of the devolatilization products, including the chemical composition of the tar, is needed. We incorporate experimental data on devolatilization products combined with modeling of the tar composition and reactions to improve the prediction of syngas compositions and carbon conversion. We also apply the shrinking core model and the random pore model to describe char consumption in the CFD simulations. Analysis of the results indicates distinct regimes of kinetic and diffusion control depending on the particle radius and injection conditions for both char oxidation and gasification reactions. The random pore model with Langmuir-Hinshelwood reaction kinetics are found to be better at predicting carbon conversion and exit syngas composition than the shrinking core model with Arrhenius kinetics. In addition, we gain qualitative and quantitative insights into the impact of the ash layer surrounding the char particle on the reaction rate.

scholarly journals Correction to An Unreacted Shrinking Core Model Serves for Predicting Combustion Rates of Organic Additives in Clay Bricks

2021 ◽  
Vol 35 (5) ◽  
pp. 4616-4616
Author(s):  
Florian Wesenauer ◽  
Christian Jordan ◽  
Mario Pichler ◽  
Aron Frei ◽  
Mudassar Azam ◽  
...  
Keyword(s):  
Core Model ◽  
Shrinking Core Model ◽  
Organic Additives ◽  
Clay Bricks ◽  
Shrinking Core

Mesopores inside electrode particles can change the Li-ion transport mechanism and diffusion-induced stress

2010 ◽  
Vol 25 (8) ◽  
pp. 1433-1440 ◽  
Author(s):  
Stephen J. Harris ◽  
Rutooj D. Deshpande ◽  
Yue Qi ◽  
Indrajit Dutta ◽  
Yang-Tse Cheng
Keyword(s):  
Core Model ◽  
Published Data ◽  
Shrinking Core Model ◽  
Stress Distributions ◽  
Active Electrode ◽  
Free Surfaces ◽  
Surface Cracking ◽  
Active Particles ◽  
Shrinking Core ◽  
And Diffusion

Following earlier work of Huggins and Nix [Ionics6, 57 (2000)], several recent theoretical studies have used the shrinking core model to predict intraparticle Li concentration profiles and associated stress fields. A goal of such efforts is to understand and predict particle fracture, which is sometimes observed in degraded electrodes. In this paper we present experimental data on LiCoO2 and graphite active particles, consistent with previously published data, showing the presence of numerous internal pores or cracks in both positive and negative active electrode particles. New calculations presented here show that the presence of free surfaces, from even small internal cracks or pores, both quantitatively and qualitatively alters the internal stress distributions such that particles are prone to internal cracking rather than to the surface cracking that had been predicted previously. Thus, the fracture strength of particles depends largely on the internal microstructure of particles, about which little is known, rather than on the intrinsic mechanical properties of the particle materials. The validity of the shrinking core model for explaining either stress maps or transport is questioned for particles with internal structure, which includes most, if not all, secondary electrode particles.

scholarly journals Macerals of Shengli Lignite in Inner Mongolia of China and Their Combustion Reactivity

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Ying Yue Teng ◽  
Yu Zhe Liu ◽  
Quan Sheng Liu ◽  
Chang Qing Li
Keyword(s):  
Activation Energy ◽  
Homogeneous Model ◽  
Optical Microscope ◽  
Core Model ◽  
Shrinking Core Model ◽  
Compact Structure ◽  
Shrinking Core ◽  
Combustion Reactivity ◽  
Combustion Processes ◽  
Kinetics Of

The macerals, including fusinitic coal containing 72.20% inertinite and xyloid coal containing 91.43% huminite, were separated from Shengli lignite using an optical microscope, and their combustion reactivity was examined by thermogravimetric analysis. Several combustion parameters, including ignition and burnout indices, were analyzed, and the combustion kinetics of the samples were calculated by regression. Fusinitic coal presented a porous structure, while xyloid coal presented a compact structure. The specific surface area of fusinitic coal was 2.5 times larger than that of xyloid coal, and the light-off temperature of the former was higher than that of the latter. However, the overall combustion reactivity of fusinitic coal was better than that of xyloid coal. The combustion processes of fusinitic and xyloid coals can be accurately described by both the homogeneous model and the shrinking core model. The features of xyloid coal agree with the shrinking core model when its conversion rate is 10%–90%. The activation energy of fusinitic coal during combustion can be divided into three phases, with the middle phase featuring the highest energy. The activation energy of xyloid coal is lower than that of fusinitic coal in the light-off phase, which may explain the low light-off temperature of this coal.

scholarly journals Kinetic Study in Atmospheric Pressure Organic Acid Leaching: Shrinking Core Model versus Lump Model

Minerals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 613
Author(s):  
Kevin Cleary Wanta ◽  
Widi Astuti ◽  
Indra Perdana ◽  
Himawan Tri Bayu Murti Petrus
Keyword(s):  
Citric Acid ◽  
Acid Solution ◽  
Acid Leaching ◽  
Core Model ◽  
Shrinking Core Model ◽  
Citric Acid Solution ◽  
Lumped Model ◽  
Leaching Process ◽  
Shrinking Core ◽  
Simulation Results

The kinetics study has an essential role in the scale-up process because it illustrates the real phenomena of a process. This study aims to develop a mathematical model that can explain the mechanism of the leaching process of laterite ore using a low concentration of the citric acid solution and evaluate that model using the experimental data. As a raw material, this process used powder-shaped limonite laterite ores with a size of 125–150 µm. The leaching process is carried out using 0.1 M citric acid solution, F:S ratio of 1:20, and a leaching time of 2 h. The temperature parameter was varied at 303, 333, and 358 K. The experimental results showed that the higher the operating temperature, the higher the extracted nickel. The results of this experiment were used to evaluate the shrinking core kinetics model and the lumped model. The simulation results for both models show that the lumped model can provide better simulation results. Quantitatively, the percentage of errors from the shrinking core model is around 3.5 times greater than the percentage of errors from using the lumped model. This result shows that in this leaching process, the process mechanism that occurs involves the reactant diffusion step and the chemical reactions step; those steps run simultaneously.

A hybrid peripheral fragmentation and shrinking-core model for fixed-bed biomass gasification

2020 ◽  
Vol 400 ◽  
pp. 124940
Author(s):  
Zhiyi Yao ◽  
Xin He ◽  
Qiang Hu ◽  
Wei Cheng ◽  
Haiping Yang ◽  
...  
Keyword(s):  
Fixed Bed ◽  
Biomass Gasification ◽  
Core Model ◽  
Shrinking Core Model ◽  
Shrinking Core
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