scholarly journals Mathematical modeling and determination of thermodynamic properties of jabuticaba peel during the drying process

2016 ◽  
Vol 20 (6) ◽  
pp. 576-580 ◽  
Author(s):  
Cristian F. Costa ◽  
Paulo C. Corrêa ◽  
Jaime D. B. Vanegas ◽  
Fernanda M. Baptestini ◽  
Renata C. Campos ◽  
...  
Keyword(s):  
Experimental Data ◽  
Thermodynamic Properties ◽  
Drying Process ◽  
Drying Temperature ◽  
Air Temperatures ◽  
Nutritional Qualities ◽  
Forced Air ◽  
Air Circulation ◽  
Best Fit

ABSTRACT Jabuticaba is a fruit native of Brazil and, besides containing many nutritional qualities, it also has a good field for use in products such as flour for cakes and biscuits, juice, liqueur, jelly and others. This study aimed to model the drying kinetics and determine the thermodynamic properties of jabuticaba peel at different drying air temperatures. Ripe fruits of jabuticaba (Myrciaria jaboticaba) were collected and pulped manually. Drying was carried out in a forced-air circulation oven with a flow of 5.6 m s-1 at temperatures of 40, 50, 60 and 70 °C. Six mathematical models commonly used to represent the drying process of agricultural products were fitted to the experimental data. The Arrhenius model was used to represent the drying constant as a function of temperature. The Midilli model showed the best fit to the experimental data of drying. The drying constant increased with the increment in drying temperature and promoted an activation energy of 37.29 kJ mol-1. Enthalpy and Gibbs free energy decreased with the increase in drying temperature, while entropy decreased and was negative.

scholarly journals Drying kinetics of ‘babassu’ mesocarp

2017 ◽  
Vol 21 (10) ◽  
pp. 709-714 ◽  
Author(s):  
Jhonatas C. Rosa ◽  
Andreza P. Mendonça ◽  
Angélica dos S. Oliveira ◽  
Sylviane B. Ribeiro ◽  
Andréia do R. Batista ◽  
...  
Keyword(s):  
Experimental Data ◽  
Water Content ◽  
Animal Feed ◽  
Coefficient Of Determination ◽  
Residual Distribution ◽  
Solar Dryer ◽  
Error Standard Deviation ◽  
Forced Air ◽  
Final Water Content ◽  
Best Fit

ABSTRACT ‘Babassu’ mesocarp flour has been used by the pharmaceutical, human food and animal feed industries. However, there is lack of standardization in the production, as well as absence of information on the management of the product’s quality. Thus, the objective of this study was to dry the ‘babassu’ mesocarp in forced-air oven and solar dryer, adjust different mathematical models to the experimental data, as well as to quantify the levels of proteins and crude fiber of the produced flour. The criteria for the adjustment were the coefficient of determination, magnitude of the mean relative error, standard deviation of estimate and the residual distribution trend. Drying in the shortest time occurred in oven at 60 °C (370 min), leading to water content of 4.62%, while in the solar dryer the final water content was 8.07% in 6 days. The mathematical model Two Terms showed the best fit to the experimental data for oven drying and the Midilli model showed the best fit in solar dryer. There was an increase in protein content with the drying in solar dryer and oven at 40, 50 and 60 °C (1.36, 1.33, 1.15 and 1.37%, respectively) in relation to fresh mesocarp (0.88%). Drying in both oven and solar dryer promoted increase of protein in the flour.

scholarly journals Determination of the hygroscopic equilibrium and isosteric heat of aji chili pepper

2017 ◽  
Vol 21 (12) ◽  
pp. 865-871 ◽  
Author(s):  
Ednilton T. Andrade ◽  
Vitor G. Figueira ◽  
Luciana P. Teixeira ◽  
José H. da S. Taveira ◽  
Flávio M. Borém
Keyword(s):  
Experimental Data ◽  
Moisture Content ◽  
Isosteric Heat ◽  
Chili Pepper ◽  
Sorption Behavior ◽  
Activity Levels ◽  
Air Humidity ◽  
Relative Air Humidity ◽  
Best Fit

ABSTRACT This study focuses on the determination of the hygroscopic equilibrium and isosteric heat of the aji chili pepper (Capsicum baccatum) under different controlled temperature and relative air humidity conditions. In addition, the objective was to adjust the model among the existing literature models that best represent the isothermal sorption behavior, as well as propose a new model to represent this phenomenon. Having obtained the mathematical models and experimental data, the best model and parameters that represent the hygroscopicity and the isosteric heat satisfactorily was determined. The temperatures used were 30, 55, and 70 °C, with water activity levels from 0.11 to 0.84. The model that best fit the data had a R2 value of 0.97. The integral isosteric heat of sorption for ‘Dedo-de-Moça’ chili pepper within a moisture content from 0.07 to 0.55 (dry basis) ranged from 3641.66 to 2614.38 kJ kg-1.

The use of electron gas modification in the evaluation of the vibration frequencies and the specific heat of lithium

1960 ◽  
Vol 259 (1298) ◽  
pp. 361-369 ◽  
Keyword(s):  
Experimental Data ◽  
Phase Transformation ◽  
Electron Gas ◽  
Vibration Frequencies ◽  
Specific Heats ◽  
Air Temperatures ◽  
Set Up ◽  
Good Agreement ◽  
Secular Determinant

A secular determinant for the determination of vibration frequencies of lithium has been set up by Launay’s method which takes the electron gas into account. Theoretical elastic constants have been used in the calculation of the force constants. Frequencies have been calculated for 47 points of the first Brillouin zone which gives the value of 3 x 1000 = 3000 frequencies by symmetry. Specific heats have been calculated by numerical computation in the range 300 to 6°K and show good agreement with the experimental data. The agreement below liquid-air temperatures is surprising in view of the known phase transformation of lithium.

scholarly journals Determination of Temperature of Components of Cotton-Raw Material in a Drum Dryer with a Constant

2021 ◽  
Vol 939 (1) ◽  
pp. 012052
Author(s):  
A Z Mamatov ◽  
A K Usmankulov ◽  
I Z Abbazov ◽  
U A Norboyev ◽  
E T Mukhametshina
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Comparative Analysis ◽  
Boundary Value Problem ◽  
Parabolic Type ◽  
Raw Material ◽  
Drying Process ◽  
Moisture State ◽  
Type Boundary

Abstract This article solves one parabolic-type boundary value problem for determining the heat-moisture state of raw cotton in drum dryers at a constant air temperature. Numerical results are obtained by the Bubnov – Galerkin method of the problem under consideration, a comparative analysis is carried out with experimental data. It is shown that the proposed mathematical model and its numerical algorithm adequately describe the drying process of raw cotton.

scholarly journals Modeling the crystallization kinetics of polymers displaying high levels of secondary crystallization

2021 ◽  
Author(s):  
Catherine A. Kelly ◽  
Mike J. Jenkins
Keyword(s):  
Experimental Data ◽  
Visual Inspection ◽  
Crystallization Process ◽  
Primary Crystallization ◽  
Parallel Model ◽  
Secondary Crystallization ◽  
Multivariable Regression ◽  
Kinetics Of ◽  
Best Fit

AbstractThe isothermal crystallization of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) was evaluated using a range of models, namely, Avrami, simplified Hillier, Tobin, Malkin, Urbanovici–Segal, Velisaris–Seferis, and Hay. Two methods of model evaluation were used: determination of the parameters through traditional double log plots and curve fitting via nonlinear, multivariable regression. Visual inspection of the cumulative crystallization curves, calculation of the R2 value and standard error of the regression, and evaluation of the returned parameters were used to assess which model best describes the experimental data. The Hay model was found to generate the best fit, closely followed by the Velisaris–Seferis parallel model, suggesting that primary and secondary crystallization occur concurrently. The Avrami, Malkin, and Tobin models were found to perform well when the data is restricted to the region where primary crystallization dominates; however, they could not be used to successfully model the entire crystallization process. This work highlights the importance of selecting the most appropriate model for analyzing kinetics, especially when high levels of lamellar thickening and infilling occur during crystallization.

scholarly journals Physical properties of safflower grains. Part II: Volumetric shrinkage

2017 ◽  
Vol 21 (5) ◽  
pp. 350-355 ◽  
Author(s):  
Elton A. S. Martins ◽  
André L. D. Goneli ◽  
Alexandre A. Gonçalves ◽  
Cesar P. Hartmann Filho ◽  
Jerusa Rech ◽  
...  
Keyword(s):  
Moisture Content ◽  
Physical Properties ◽  
Initial Moisture Content ◽  
Linear Shrinkage ◽  
Agricultural Products ◽  
Volumetric Shrinkage ◽  
Drying Process ◽  
Moisture Contents ◽  
Forced Air ◽  
Air Circulation

ABSTRACT Agricultural products usually have their size reduced during the drying process. The quantification of the reduction in the dimensions is important for the development and optimization of equipment for the post-harvest of the product. The aim of the present study was to evaluate the effect of the variation in the moisture content during drying on the volumetric shrinkage of safflower grains and their respective axes. Safflower grains were harvested with an initial moisture content of approximately 0.445 decimal d.b. (dry basis) and subjected to drying in an oven with forced air circulation at 40 °C, until the grains reached a final moisture content of 0.073 ± 0.008 decimal d.b. During drying, the contraction of the axes, unit volumetric shrinkage and volumetric shrinkage of the mass of safflower grains were determined at different moisture contents. Based on these results, it can be concluded that reducing the moisture content causes a reduction in the axes of safflower grains and, consequently, reductions in the unit volumetric shrinkage and volumetric shrinkage of the mass of approximately 16 and 13%, respectively, and both variables can be represented by the linear shrinkage model.

Study of the water-bentonite system by vapour adsorption, immersion calorimetry and X-ray techniques: II. Heats of immersion, swelling pressures and thermodynamic properties

Clay Minerals ◽  
1990 ◽  
Vol 25 (4) ◽  
pp. 499-506 ◽  
Author(s):  
G. Kahr ◽  
F. Kraehenbuehl ◽  
H. F. Stoeckli ◽  
M. Müller-Vonmoos
Keyword(s):  
Experimental Data ◽  
Free Energy ◽  
Thermodynamic Properties ◽  
Adsorption Isotherms ◽  
Water Adsorption ◽  
Immersion Calorimetry ◽  
X Ray ◽  
Vapour Adsorption ◽  
Heats Of Immersion

AbstractA number of thermodynamic properties were obtained from the determination of adsorption isotherms and enthalpies of immersion for systems with water and Na- and Ca-bentonites. Entropy differences were calculated by combining the enthalpies of immersion and the changes in free energy derived from the adsorption isotherms. The swelling pressures, also calculated from the water adsorption isotherms, are in satisfactory agreement with the experimental data.

scholarly journals Hygroscopic Behavior and Thermodynamic Properties of Ziziphus joazeiro Mart. Kernel Flour

2020 ◽  
Vol 8 (3) ◽  
pp. 50
Author(s):  
Hanndson Araujo Silva ◽  
Josivanda Palmeira Gomes ◽  
Alexandre José de Melo Queiroz
Keyword(s):  
Experimental Data ◽  
Thermodynamic Properties ◽  
Moisture Content ◽  
Isosteric Heat ◽  
Type Ii ◽  
Differential Entropy ◽  
Differential Enthalpy ◽  
Gab Model ◽  
Hygroscopic Behavior ◽  
Best Fit

The hygroscopic and thermal behavior of kernel flour from Ziziphus joazeiro fruits were investigated. Adsorption isotherms were obtained at temperatures of 293, 303 and 313 K and adjusted to GAB, Oswin and Peleg models. The best fit of the experimental data was obtained with the GAB model with R² values> 0.994 and mean percentage deviation P <10%. The isotherms obtained were sigmoidal type II. Isosteric heat and other thermodynamic properties were calculated as a function of moisture content. Adsorption isosteric heat decreased exponentially with increasing moisture content and differential entropy increased with moisture content, while differential enthalpy decreased. The theory of compensation confirmed that these properties are dependent on moisture content. The isotherms presented a spontaneous and enthalpy process.

Selection of Adsorbents and Determination of Parameters for the Separation of Glucose, Fructose, Sucrose and Fructooligosaccharides

2010 ◽  
Vol 6 (6) ◽  
Author(s):  
Raquel Cristine Kuhn ◽  
Francisco Maugeri Filho
Keyword(s):  
Experimental Data ◽  
Active Carbon ◽  
The Other ◽  
Isothermal Kinetics ◽  
Nax Zeolite ◽  
Selection Step ◽  
Determination Of Parameters ◽  
Best Fit ◽  
Selection Of

This work aimed to describe the adsorption of sugars (glucose, fructose, sucrose and fructooligosaccharides) employing different adsorbents (celite, active carbon and NaX zeolite) by means of isothermal models. At the adsorbent selection step, the active carbon exhibited a higher affinity for the adsorption of fructooligosaccharides. On the other hand, the adsorbents NaX zeolite and celite presented the highest adsorption stability with glucose, giving values of 1.496 g glucose/g zeolite and 1.35 g glucose/g celite. Therefore, zeolite and celite were the adsorbents selected for the determination of isothermal kinetics and it was shown that the linear model (q*= k.C*) provided the best fit for the experimental data. The temperatures studied were 30, 40 and 50 °C, and the 50°C resulted in the highest partition coefficient (k) for glucose on celite, indicating that higher temperatures benefit sugar adsorption.

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