scholarly journals Modélisation mathématique du séchage dans un four (air chaud) de tranches de mangue (Mangiféra indica L.)

2020 ◽  
Vol 14 (7) ◽  
pp. 2476-2490
Author(s):  
N’guessan Verdier Abouo ◽  
Alhassane Fofana ◽  
Yevi Delphine N’guessan ◽  
Nogbou Emmanuel Assidjo
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Mangifera Indica ◽  
Gravimetric Method ◽  
Empirical Models ◽  
Factor Matrix ◽  
Hot Air ◽  
Modélisation Mathématique ◽  
Experimental Values ◽  
Statistical Criteria

Ce travail vise à étudier le séchage de la mangue à différentes épaisseurs et températures en vue de valorisation. Les expériences ont été menées à partir d’une matrice factorielle par la méthode gravimétrique statique. Les valeurs expérimentales ont été ajustées à huit modèles empiriques par la méthode du gradient afin d’estimer les paramètres et coefficients des modèles. Les critères statistiques que sont le R², l’erreur quadratique moyenne (EQM) et le χ² ont servi à justifier le choix du modèle de séchage. Le séchage a duré 16-18 ; 23-27 et 29-33 minutes respectivement aux températures 60, 50 et 40°C pour les épaisseurs 1,5 et 1 cm. Le modèle logarithmique est retenu et présente les valeurs du R² (0,9984 ; 0,9984 ; 0,9981 ; 0,9987 ; 0,9988 ; 0,9985) les plus élevées et les plus faibles valeurs de χ² (2,43 e-07 ; 1,58 e-07 ; 1,25 e-06 ; 2,02 e-07 ; 4,56 e-06 et 1,37 e-06) et EQM (2,42 e-04 ; 1,95 e-07 ; 5,47 e-04 ; 2,20 e-04 ; 0,0010 et 5,69 e-04). Le coefficient de diffusion varie de 8,615 e-09 à 9,155 e-09 m² / s et dépend fortement de la température de séchage. L’énergie d’activation est estimée entre 22,430 – 25,358 KJ / mol.Mots clés : Séchage, mangue, modèle, coefficient de diffusion, énergie d’activation.   English Title: Mathematical modeling of the drying in an oven (hot air) of slices of mango (Mangifera indica L.)This work aims to study the drying of mango at different thicknesses and temperatures a view to valorization. The experiments were carried out from a factor matrix by the static gravimetric method. The experimental values were fitted to eight empirical models by the gradient method in order to estimate the parameters and coefficients of the models. The statistical criteria of R², mean square error (MSE) and χ² were used to justify the choice of the drying model. Drying lasted 16-18; 23-27 and 29-33 minutes respectively at temperatures 60, 50 and 40 °C for thicknesses 1.5 and 1 cm. The logarithmic model is retained and presents the highest values of R² (0.9984; 0.9984; 0.9981; 0.9987; 0.9988; 0.9985) and the lowest values of χ² (2.43 e-07; 1.58 e-07; 1.25 e-06; 2.02 e-07; 4.56 e-06 and 1.37 e-06) and MSE (2.42 e-04; 1.95 e-07; 5.47 e-04; 2.20 e-04; 0.0010 and 5.69 e-04). The diffusion coefficient varies from 8.615 e-09 to 9.155 e-09 m² / s and strongly depends on the drying temperature. The activation energy is estimated to be 22.430 - 25.358 KJ / mol.Keywords : Drying, mango, models, diffusion coefficient, activation energy.

scholarly journals Insights into the interactions and dynamics of a DES formed by phenyl propionic acid and choline chloride

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Parisa Jahanbakhsh Bonab ◽  
Alireza Rastkar Ebrahimzadeh ◽  
Jaber Jahanbin Sardroodi
Keyword(s):  
Diffusion Coefficient ◽  
Liquid Phase ◽  
Propionic Acid ◽  
Structural Parameters ◽  
Choline Chloride ◽  
Self Diffusion ◽  
Phenyl Propionic Acid ◽  
Donor And Acceptor ◽  
Experimental Values ◽  
Self Diffusion Coefficient

AbstractDeep eutectic solvents (DESs) have received much attention in modern green chemistry as inexpensive and easy to handle analogous ionic liquids. This work employed molecular dynamics techniques to investigate the structure and dynamics of a DES system composed of choline chloride and phenyl propionic acid as a hydrogen bond donor and acceptor, respectively. Dynamical parameters such as mean square displacement, liquid phase self-diffusion coefficient and viscosity are calculated at the pressure of 0.1 MPa and temperatures 293, 321 and 400 K. The system size effect on the self-diffusion coefficient of DES species was also examined. Structural parameters such as liquid phase densities, hydrogen bonds, molecular dipole moment of species, and radial and spatial distribution functions (RDF and SDF) were investigated. The viscosity of the studied system was compared with the experimental values recently reported in the literature. A good agreement was observed between simulated and experimental values. The electrostatic and van der Waals nonbonding interaction energies between species were also evaluated and interpreted in terms of temperature. These investigations could play a vital role in the future development of these designer solvents.

scholarly journals Surface Thermodynamics, Viscosity, Activation Energy of N-Methyldiethanolamine Aqueous Solutions Promoted by Tetramethylammonium Arginate

Entropy ◽  
2020 ◽  
Vol 22 (12) ◽  
pp. 1337
Author(s):  
Xiangfeng Tian ◽  
Lemeng Wang ◽  
Pan Zhang ◽  
Dong Fu
Keyword(s):  
Activation Energy ◽  
Surface Tension ◽  
Diffusion Coefficient ◽  
Aqueous Solutions ◽  
Quantitative Relationship ◽  
Viscosity Data ◽  
Surface Thermodynamics ◽  
Surface Entropy ◽  
Operation Conditions ◽  
Surface Enthalpy

The surface tension and viscosity values of N-methyldiethanolamine (MDEA) aqueous solutions promoted by tetramethylammonium arginate ([N1111][Arg]) were measured and modeled. The experimental temperatures were 303.2 to 323.2 K. The mass fractions of MDEA (wMDEA) and [N1111][Arg] (w[N1111][Arg]) were 0.300 to 0.500 and 0.025 to 0.075, respectively. The measured surface tension and viscosity values were satisfactorily fitted to thermodynamic models. With the aid of experimentally viscosity data, the activation energy (Ea) and H2S diffusion coefficient (DH2S) of MDEA-[N1111][Arg] aqueous solution were deduced. The surface entropy and surface enthalpy of the solutions were calculated using the fitted model of the surface tension. The quantitative relationship between the calculated values (surface tension, surface entropy, surface enthalpy, viscosity, activation energy, and H2S diffusion coefficient) and the operation conditions (mass fraction and temperature) was demonstrated.

scholarly journals Unexpected Role of Electronic Coupling between Host Redox Centers in Transport Kinetics of Lithium Ions in Olivine Phosphate Materials

2021 ◽  
Author(s):  
Yu Gao ◽  
Jun Huang ◽  
Yuwen Liu ◽  
Shengli Chen
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Lithium Ion ◽  
Transport Kinetics ◽  
Electronic Coupling ◽  
Lithium Ions ◽  
Kinetics Of ◽  
Olivine Phosphate ◽  
Redox Centers

The discrepancy between the trend in the diffusion coefficient of lithium ion (DLi+) and that in the activation energy of ion hopping signals hidden factors determining ion transport kinetics in...

scholarly journals Drying Kinetics of Noni Seeds

2019 ◽  
Vol 11 (5) ◽  
pp. 250 ◽  
Author(s):  
Wellytton Darci Quequeto ◽  
Osvaldo Resende ◽  
Patrícia Cardoso Silva ◽  
Fábio Adriano Santos e Silva ◽  
Lígia Campos de Moura Silva
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Diffusion Coefficient ◽  
Moisture Content ◽  
Mathematical Models ◽  
Effective Diffusion Coefficient ◽  
Effective Diffusion ◽  
Information Criterion ◽  
Drying Kinetics ◽  
Kinetics Of

Noni seeds have been used for years as an important medicinal source, with wide use in the pharmaceutical and food industry. Drying is a fundamental process in the post-harvest stages, where it enables the safe storage of the product. Therefore, the present study aimed to fit different mathematical models to experimental data of drying kinetics of noni seeds, determine the effective diffusion coefficient and obtain the activation energy for the process during drying under different conditions of air temperature. The experiment used noni seeds with initial moisture content of 0.46 (decimal, d.b.) and dehydrated up to equilibrium moisture content. Drying was conducted under different controlled conditions of temperature, 40; 50; 60; 70 and 80 ºC and relative humidity, 24.4; 16.0; 9.9; 5.7 and 3.3%, respectively. Eleven mathematical models were fitted to the experimental data. The parameters to evaluate the fitting of the mathematical models were mean relative error (P), mean estimated error (SE), coefficient of determination (R2), Chi-square test (c2), Akaike Information Criterion (AIC) and Schwarz’s Bayesian Information Criterion (BIC). Considering the fitting criteria, the model Two Terms was selected to describe the drying kinetics of noni seeds. Effective diffusion coefficient ranged from 8.70 to 23.71 × 10-10 m2 s-1 and its relationship with drying temperature can be described by the Arrhenius equation. The activation energy for noni seeds drying was 24.20 kJ mol-1 for the studied temperature range.

Te Induced AlAs/GaAs Superlattice Mixing

1988 ◽  
Vol 126 ◽  
Author(s):  
P. Mel ◽  
S. A. Schwarz ◽  
T. Venkatesan ◽  
C. L. Schwartz ◽  
E. Colas
Keyword(s):  
Mass Spectrometry ◽  
Activation Energy ◽  
Diffusion Coefficient ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Secondary Ion Mass Spectrometry ◽  
Chemical Vapor ◽  
Temperature Range ◽  
The Relationship ◽  
Secondary Ion

ABSTRACTTe enhanced mixing of AlAs/GaAs superlattice has been observed by secondary ion mass spectrometry. The superlattice sample was grown by organometallic chemical vapor deposition and doped with Te at concentrations of 2×1017 to 5×1018 cm−.3 In the temperature range from 700 to 1000 C, a single activation energy for the Al diffusion of 2.9 eV was observed. Furthermore, it has been found that the relationship between the Al diffusion coefficient and Te concentration is linear. Comparisons have been made between Si and Te induced superlattice mixing.

Investigation of hydrogen diffusion behavior in 12Cr2Mo1R(H) steel by electrochemical tests and first-principles calculation

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xiang Qiu ◽  
Kun Zhang ◽  
Qin Kang ◽  
Yicheng Fan ◽  
Hongyu San ◽  
...  
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Hydrogen Atom ◽  
Hydrogen Embrittlement ◽  
First Principles ◽  
Hydrogen Diffusion ◽  
First Principles Calculations ◽  
Content Type ◽  
Diffusion Behavior ◽  
Hydrogen Diffusion Coefficient

Purpose This paper aims to study the mechanism of hydrogen embrittlement in 12Cr2Mo1R(H) steel, which will help to provide valuable information for the subsequent hydrogen embrittlement research of this kind of steel, so as to optimize the processing technology and take more appropriate measures to prevent hydrogen damage. Design/methodology/approach The hydrogen diffusion coefficient of 12Cr2Mo1R(H) steel was measured by the hydrogen permeation technique of double electrolytic cells. Moreover, the influence of hydrogen traps in the material and experimental temperature on hydrogen diffusion behavior was discussed. The first-principles calculations based on density functional theory were used to study the occupancy of H atoms in the bcc-Fe cell, the diffusion path and the interaction with vacancy defects. Findings The results revealed that the logarithm of the hydrogen diffusion coefficient of the material has a linear relationship with the reciprocal of temperature and the activation energy of hydrogen atom diffusion in 12Cr2Mo1R(H) steel is 23.47 kJ/mol. H atoms stably exist in the nearly octahedral interstices in the crystal cell with vacancies. In addition, the solution of Cr/Mo alloy atom does not change the lowest energy path of H atom, but increases the diffusion activation energy of hydrogen atom, thus hindering the diffusion of hydrogen atom. Cr/Mo and vacancy have a synergistic effect on inhibiting the diffusion of H atoms in α-Fe. Originality/value This article combines experiments with first-principles calculations to explore the diffusion behavior of hydrogen in 12Cr2Mo1R(H) steel from the macroscopic and microscopic perspectives, which will help to establish a calculation model with complex defects in the future.

Determination of transport constants of isolated Nitella cell walls

1968 ◽  
Vol 46 (4) ◽  
pp. 317-327 ◽  
Author(s):  
M. T. Tyree
Keyword(s):  
Activation Energy ◽  
Cell Wall ◽  
Diffusion Coefficient ◽  
Cell Walls ◽  
Transport Coefficients ◽  
Irreversible Thermodynamics ◽  
Kcal Mole ◽  
Limiting Value ◽  
Nitella Flexilis

Transport coefficients LPP, LPE, LEP, and LEE for electrokinetic equations according to irreversible thermodynamics, the Onsager coefficients, were measured for isolated Nitella flexilis cell walls in KCl solutions ranging from 10−4 to 100 normal. LPP and LPE (= LEP) were found to be independent of KCl concentration and equal to 1.4 × 10−6 cm3 sec−1 cm−2 (joule cm−3)−1 cm and 6 × 10−5 cm3 sec−1 cm−2 volt−1 cm respectively. LEE was a function of the salt concentration, reaching a limiting value of about 1.2 × 10−3 mho cm−1 in 10−4 N KCl. The activation energy for movement of KCl in cell walls was found to be 4.33 Kcal mole−1; the diffusion coefficient for KCl in cell walls was calculated by two methods to be 8 × 10−6 cm2 sec−1; and the concentration of the fixed ions in Nitella cell walls from the above data was estimated at greater than 0.04 equivalent per liter of cell wall. Electroosmosis in Nitella membranes is re-examined in the light of the measured transport coefficients and it is concluded that under proper conditions the cell wall of Nitella can contribute significantly (~20% or more) to the observed electroosmosis of living Nitella cells.

Empirical Models for a Screw Expander Based on Experimental Data From Organic Rankine Cycle System Testing

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Vamshi Krishna Avadhanula ◽  
Chuen-Sen Lin
Keyword(s):  
Experimental Data ◽  
Power Output ◽  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Volume Ratio ◽  
Rankine Cycle ◽  
Empirical Models ◽  
Working Fluid ◽  
Work Output ◽  
Experimental Values

The screw expander discussed in this work was part of a 50 kW organic Rankine cycle (ORC) system. The ORC was tested under different conditions in heat source and heat sink. In conjunction with collecting data for the ORC system, experimental data were also collected for the individual components of the ORC, viz. evaporator, preheater, screw expander, working fluid pump, and condenser. Experimental data for the screw expander were used to develop the two empirical models discussed in this paper for estimating screw expander performance. As the physical parameters of the screw expander discussed in this article are not known, a “black-box” approach was followed to estimate screw expander power output, based on expander inlet and outlet pressure and temperature data. Refrigerant R245fa was used as the working fluid in the ORC. The experimental data showed that the screw expander had ranges of pressure ratio (2.70 to 6.54), volume ratio (2.54 to 6.20), and power output (10 to 51.5 kW). Of the two empirical models, the first model is based on the polytropic expansion process, in which an expression for the polytropic exponent is found by applying regression curve-fitting analysis as a function of the expander pressure ratio and volume ratio. In the second model, an expression for screw expander work output is found by applying regression curve-fitting analysis as a function of the expander isentropic work output. The predicted screw expander power output using the polytropic exponent model was within ±10% of experimental values; the predicted screw expander power output using the isentropic work output model was within ±7.5% of experimental values.

The Contribution of Diffusion Coefficient to the Eutectic Instability and Amorphous Phase Formation

2010 ◽  
Vol 654-656 ◽  
pp. 1355-1358 ◽  
Author(s):  
Nan Wang ◽  
Xiao Wang ◽  
Wen Jing Yao
Keyword(s):  
Diffusion Coefficient ◽  
Amorphous Phase ◽  
Growth Velocity ◽  
Diffusion Length ◽  
Eutectic Growth ◽  
Maximum Growth ◽  
Interface Growth ◽  
Maximum Undercooling ◽  
Experimental Values ◽  
Amorphous Phase Formation

The diffusion coefficient D decides the diffusion length of solute boundary and plays a key role in the microstructure selection. This paper examines quantitatively the contribution of diffusion coefficient to the eutectic instability and amorphorization ability. The maximum growth velocity Vmax and the maximum undercooling Tmax as functions of activation energy Q in strong liquids are deduced theoretically based on eutectic growth model by separating Q from D. It reveals that the larger the Q, the smaller the Tmax and Vmax, which shows the same tendency as experimental values in some Al-based alloys and glass formers. This indicates that it is the sluggish movement of atoms that makes the transition from eutectic to others structural morphologies, even to amorphous phase, occur at smaller interface growth velocity or undercooling, which is the main contribution of the diffusion coefficient to the amorphorization ability.

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