The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Diego Elustondo - One of the best experts on this subject based on the ideXlab platform.
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basic density determination for swedish softwoods and its influence on Average Moisture Content of wood packages estimated by measuring their mass
Wood Material Science and Engineering, 2016Co-Authors: Tommy Vikberg, Diego ElustondoAbstract:AbstractIn this work, a set-up with a device measuring the mass of wood packages is examined as an aid to estimate the Average Moisture Content (MC) of wood packages. As the basic density needs to be presumed in the set-up, an estimator of the basic density as a function of log diameter is determined for Norway spruce (Picea abies (L.) Karst) and Scots pine (Pinus sylvestris). In total, 1920 specimens were collected at two different sawmills and analysed for this purpose. Specimens collected at the butt-end of pine had the greatest variation in basic density and it is recommended that they should be omitted when sawmills create their own functions for basic density estimation. Furthermore, the variation in basic density was shown to have the greatest impact on the estimated MC. A maximum error estimator of the MC became 14% at a MC of 70% and 9% at a MC of 10%. It was therefore concluded that the described method should not be used to estimate the MC of packages after drying but can serve as a valuable in...
Tommy Vikberg - One of the best experts on this subject based on the ideXlab platform.
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basic density determination for swedish softwoods and its influence on Average Moisture Content of wood packages estimated by measuring their mass
Wood Material Science and Engineering, 2016Co-Authors: Tommy Vikberg, Diego ElustondoAbstract:AbstractIn this work, a set-up with a device measuring the mass of wood packages is examined as an aid to estimate the Average Moisture Content (MC) of wood packages. As the basic density needs to be presumed in the set-up, an estimator of the basic density as a function of log diameter is determined for Norway spruce (Picea abies (L.) Karst) and Scots pine (Pinus sylvestris). In total, 1920 specimens were collected at two different sawmills and analysed for this purpose. Specimens collected at the butt-end of pine had the greatest variation in basic density and it is recommended that they should be omitted when sawmills create their own functions for basic density estimation. Furthermore, the variation in basic density was shown to have the greatest impact on the estimated MC. A maximum error estimator of the MC became 14% at a MC of 70% and 9% at a MC of 10%. It was therefore concluded that the described method should not be used to estimate the MC of packages after drying but can serve as a valuable in...
A.g. Barbosa De Lima - One of the best experts on this subject based on the ideXlab platform.
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Water Absorption in Caroá-Fiber Reinforced Polymer Composite at Different Temperatures: A Theoretical Investigation
Diffusion Foundations, 2017Co-Authors: C.j. Silva, A.g. Barbosa De Lima, T.h.f. De Andrade, E.g. Silva, R.q. Da Costa MeloAbstract:Water uptake studies of composite materials reinforced with vegetable fibers shows that they are highly sensitive to environmental influences such as water and temperature. The presence of Moisture leads to impregnation and imperfect interfacial fiber-matrix adhesion, which generate internal stresses porosity and premature system failure. Accordingly, the aim of this work is to study theoretically water absorption in unsaturated polyester composites reinforced with caroa fiber (Neoglaziovia Variegata) at 25, 50 and 70°C by using a transient 3D mathematical model via ANSYS CFX® Software. The samples has composition 30% caroa fiber/70% unsaturated polyester resin and dimensions 6 x 20 x 20 mm3. Results of the Average Moisture Content and Moisture Content distribution during the water uptake are presented and analyzed. Comparison between numerical and experimental data of the Average Moisture Content showed good agreement. It can be concluded that the water absorption rate is faster in the vertex region of the composites, and mainly at higher temperature.
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Water Absorption in Polymer Composites Reinforced with Vegetable Fiber Using Langmuir-Type Model: An Exact Mathematical Treatment
Defect and Diffusion Forum, 2017Co-Authors: W.r. Gomes Dos Santos, R.q. Da Costa Melo, A.g. Barbosa De LimaAbstract:This work presents a theoretical study of the anomalous behavior of Moisture transient diffusion in vegetable fiber-reinforced composites materials using Langmuir-type model. For obtain the analytical solution was used the Laplace transform technique. Results of the absorption kinetics and concentration distribution of water (free and trapped water molecules) within the material along the process are presented and analyzed. Predicted results compared to experimental data of Average Moisture Content have shown that the model was effective for description of the phenomenon, allowing a better understanding about the effects of Moisture migration mechanisms.
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Clay Products Convective Drying: Foundations, Modeling and Applications
Advanced Structured Materials, 2015Co-Authors: A.g. Barbosa De Lima, J. Barbosa Da Silva, G. S. Almeida, José Jefferson Da Silva Nascimento, F. V. S. Tavares, Veralúcia Severina SilvaAbstract:This chapter briefly focuses on the theory and applications of drying process with particular reference to wet clay product. Herein, a modeling based on the heat and liquid diffusion theories including dimensions variations and hygro-thermal-elastic stress analysis, and the mathematical formalism to obtain the numerical solution of the governing equations using finite-volume method are presented. The model considers constant thermo-physical properties and convective boundary conditions at the surface of the solid. Applications have been done to ceramic hollow brick. Predicted results of the Average Moisture Content, surface temperature, and Moisture Content, temperature and stress distributions within the porous solids are shown and analyzed, and for some drying situations they are compared with experimental drying data of the Average Moisture Content and surface temperature of the brick along the continuous drying process.
Antonio Gilson Barbosa De Lima - One of the best experts on this subject based on the ideXlab platform.
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On the Modeling of Drying Process in an Industrial Tunnel Dryer
Defect and Diffusion Forum, 2020Co-Authors: Francisca Valdeiza De Souza Tavares, Atacy Maciel De Melo Cavalcante, Maria José Figueiredo, Anderson F. Vilela, Ana Raquel Carmo De Lima, Luan Pedro Melo Azerêdo, Antonio Gilson Barbosa De LimaAbstract:This paper aims to study convective drying of industrial hollow bricks in a tunnel dryer. A transient mathematical model based on the heat and mass conservation equations applied to the air and brick was derived and the numerical solution (finite-volume method) of the governing equations is presented. Predicted and experimental data of the Average Moisture Content and the temperature of the product during the drying process are compared and a good concordance was verified. Numerical results inside the bed confirm an almost null difference between the Moisture Content along the process. Similar behavior was verified to the product temperature. These results confirm an efficient drying process.
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Drying of Sisal Fiber: Three-Dimensional Mathematical Modeling and Simulation
Defect and Diffusion Forum, 2020Co-Authors: Jaqueline Félix De Brito Diniz, José Jefferson Da Silva Nascimento, Gicelia Moreira, Rodolfo Pereira De Farias, Hortência Luma Fernandes Magalhães, Gustavo Henrique De Almeida Barbalho, Antonio Gilson Barbosa De LimaAbstract:This work presents a theoretical drying study of sisal fiber. Fibers with Moisture Content of around 11.2% were dried in an oven in the temperature 90°C. A transient and three-dimensional mathematical modeling to predict heat and mass transfer in a bed of fiber was proposed and numerically solved by using the finite-volume method. Results of the Average Moisture Content and surface temperature were compared with experimental data to verify the consistence of the proposed model, and good agreement was verified.
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Water Absorption in Composites Reinforced with Caroá Fiber Fabrics: Modeling and Simulation via ANSYS CFX®
Defect and Diffusion Forum, 2014Co-Authors: C.j. Silva, T.h.f. De Andrade, E.g. Silva, Antonio Gilson Barbosa De LimaAbstract:Studies in polymer composites reinforced with vegetable fiber show that they are enough sensitive to influences from environmental agents such as water and temperature. The Moisture causes degradation of the mechanical properties of natural fiber reinforced composites to a large extent when compared to synthetic fiber reinforced composites. This is a consequence of the higher Moisture absorption, and the hydrofilic nature of the natural fiber. In this sense, the purpose of this work is to study theoretically the water absorption in unsaturated polyester composites reinforced with caroa natural fiber (Neoglaziovia variegata) at the temperature 50°C. The composite had a weight composition of 30% caroa and 70% unsaturated polyester resin and dimensions of 20× 20× 3 mm3. Results of the Average Moisture Content and Moisture Content distribution during the absorption process are presented and analyzed. Comparison between numerical and experimental data of the Average Moisture Content presented good agreement. We conclude that the water absorption rate is faster in the vertex region of the composites.
Sergio A. Giner - One of the best experts on this subject based on the ideXlab platform.
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Influence of Internal and External Resistances to Mass Transfer on the constant drying rate period in high-Moisture foods
Biosystems Engineering, 2020Co-Authors: Sergio A. GinerAbstract:Food drying kinetics is usually studied by measuring the product Average Moisture Content as a function of time, known as the drying curve, for constant air conditions. The slope of this curve is the drying rate. Most food drying studies consider that the drying rate decreases from the start, and propose the use of diffusion models. However, some authors have observed that in high-Moisture foods there is an initial period with a constant drying rate and a linear drying curve which is assumed to be externally controlled. A model similar to that used for pure water evaporation is usually proposed but this does not consider internal Moisture gradients. Here, drying curves were recorded for fruit pectic gels and an initial linear variation of the drying curve was observed. By applying an analytical solution of diffusion for mass transfer Biot number = 2, (the internal resistance is twice the external) in plane sheets, the linear behaviour was predicted for the Average Moisture Content at early stages in the drying curve. However, a variant of this solution, which predicts Moisture Content as a function of time for the surface and several positions within the plane sheet, was utilised. Under the same conditions, it was found that all curves differed one to the other (internal gradients) and none was linear. Linear drying behaviour therefore appears to be restricted to the Average Moisture Content only and for a limited period, and thus the constant rate period of drying in high-Moisture foods does not follow convective, purely external controls.
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Drying–toasting kinetics of presoaked soybean. A mathematical model considering variable diffusivity, shrinkage and coupled heat transfer
Journal of Food Engineering, 2014Co-Authors: R.m. Torrez Irigoyen, Sandro M. Goñi, Sergio A. GinerAbstract:In this work, the kinetics of drying–toasting of presoaked soybean in fludised thin layer at air temperatures between 100 and 160 °C was mathematically modeled. A two-stage shrinkage model was developed, which relates soybean radius with the Average Moisture Content. Spherical geometry was assumed with radial diffusion, and a local mass balance coupled with an overall heat balance in the soybeans was solved by finite difference and the Euler method, respectively. The heat transfer coefficient was estimated from the energy balance using experimental drying rates. Values varied from 176 to 312 W/(m2 °C). The effective diffusion coefficient was proposed to be a function of temperature and Moisture Content. The temperature dependence was described by an Arrhenius relationship, while the Moisture Content dependence, found by extending the shrinkage behavior to a local level. The Arrhenius parameters were estimated by solving an inverse problem for the whole dataset. The activation energy was 51.9 kJ/(mol K), with a pre-exponential factor of 0.0237 m2/s. Predicted temperatures and Average Moisture Content agreed well with experimental measurements.