MOISTURE DIFFUSION COEFFICIENTS OF SINGLE WHEAT KERNELS WITH ASSUMED SIMPLIFIED GEOMETRIES: ANALYTICAL APPROACH

2000 ◽  
Vol 43 (6) ◽  
pp. 1653-1659 ◽  
Author(s):  
S. Kang ◽  
S. R. Delwiche
Keyword(s):  
Diffusion Coefficients ◽  
Analytical Approach ◽  
Moisture Diffusion ◽  
Wheat Kernels

Prediction of Trifluralin Diffusion Coefficients

Weed Science ◽  
1973 ◽  
Vol 21 (5) ◽  
pp. 485-489 ◽  
Author(s):  
L. E. Bode ◽  
C. L. Day ◽  
M. R. Gebhardt ◽  
C. E. Goering
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Diffusion Coefficients ◽  
Moisture Diffusion ◽  
Soil Parameters ◽  
Void Space ◽  
Exponential Relationship ◽  
Maximum Value ◽  
Soil Temperatures ◽  
Dry Soil

In the range of 4.4 to 49 C, there is an exponential relationship between temperature and trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) diffusion coefficients. Diffusion is low in air-dry soil for all temperatures. It increases to a maximum value when the soil has between 8 and 15% w/w soil moisture content and then decreases steadily as moisture content increases. When the air-filled fraction of soil void space is reduced below approximately 40% v/v by either compression or addition of moisture, diffusion begins to decrease. An equation was developed to predict trifluralin diffusion coefficients from a factorial experiment with seven soil moisture contents, five soil temperatures, and two bulk densities. Diffusion coefficients range from 3.8 X 10-11 cm2/sec to 2.8 X 10-6 cm2/sec. Fifteen terms are required in the prediction model to describe accurately the response surface of trifluralin diffusion coefficients. With the equation it is possible to predict trifluralin diffusion coefficients for any combination of measured soil parameters as long as they are represented by the range of the variables used in the experiment.

Computer Aided Identification of the Moisture Transport Parameters in Spruce Wood

Holzforschung ◽  
2003 ◽  
Vol 57 (5) ◽  
pp. 533-538 ◽  
Author(s):  
P. Koc ◽  
M. Houka ◽  
B. Štok
Keyword(s):  
Inverse Problem ◽  
Moisture Content ◽  
Diffusion Coefficients ◽  
Moisture Diffusion ◽  
Transport Parameters ◽  
Moisture Flow ◽  
Identification Method ◽  
Three Samples ◽  
Computer Aided

Summary An inverse identification method for characterization of wood sorptive properties is presented. The method relies on a computer simulation of a real experiment, in our case a desorption experiment, where spruce heartwood samples were dried from 27% to 8% moisture content. Three samples, distinguished by the respective moisture flow pattern through the specimen, were investigated. A computer aided material characterization using the so-called inverse problem identification method was performed on the measurements. The solution of the specified inverse problem enabled us to estimate the moisture diffusion coefficients of wood and to determine the moisture content field in the sample simultaneously. The method is first verified on two simple cases of uniaxial moisture flow, and then is used to characterize the diffusion coefficients on a biaxial moisture flow sample. In the latter case some salient features of the proposed method are exhibited.

scholarly journals Kinetic Studies and Moisture Diffusivity During Cocoa Bean Roasting

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 770 ◽  
Author(s):  
Leydy Ariana Domínguez-Pérez ◽  
Ignacio Concepción-Brindis ◽  
Laura Mercedes Lagunes-Gálvez ◽  
Juan Barajas-Fernández ◽  
Facundo Joaquín Márquez-Rocha ◽  
...  
Keyword(s):  
Diffusion Coefficients ◽  
Kinetic Studies ◽  
Moisture Diffusion ◽  
Moisture Diffusivity ◽  
Cocoa Bean ◽  
Exponential Models ◽  
First Order ◽  
Roasting Process ◽  
Pseudo First Order ◽  
Semi Empirical

Cocoa bean roasting allows for reactions to occur between the characteristic aroma and taste precursors that are involved in the sensory perception of chocolate and cocoa by-products. This work evaluates the moisture kinetics of cocoa beans during the roasting process by applying empirical and semi-empirical exponential models. Four roasting temperatures (100, 140, 180, and 220 °C) were used in a cylindrically designed toaster. Three reaction kinetics were tested (pseudo zero order, pseudo first order, and second order), along with 10 exponential models (Newton, Page, Henderson and Pabis, Logarithmic, Two-Term, Midilli, Verma, Diffusion Approximation, Silva, and Peleg). The Fick equation was applied to estimate the diffusion coefficients. The dependence on the activation energy for the moisture diffusion process was described by the Arrhenius equation. The kinetic parameters and exponential models were estimated by non-linear regression. The models with better reproducibility were the pseudo first order, the Page, and the Verma models (R2 ≥ 0.98). The diffusion coefficients that were calculated were in the order of 1.26 to 5.70 × 109 m s−2 and the energy activation for moisture diffusion obtained was 19.52 kJ mol−1.

Moisture Sorption and Desorption in Epoxy Composites Reinforced with Triangular and V-Shaped Bars: Determination of Diffusion Coefficient and Effect of Varied Factors

2018 ◽  
Vol 383 ◽  
pp. 43-48
Author(s):  
B. Pajarito ◽  
Myan Trishia de Leon ◽  
Eugene Rex A. Pacumio
Keyword(s):  
Diffusion Coefficient ◽  
Weight Change ◽  
Diffusion Coefficients ◽  
Vinyl Ester ◽  
Moisture Sorption ◽  
Moisture Diffusion ◽  
Epoxy Composites ◽  
Cross Sectional ◽  
Base Side ◽  
Sectional Shape

Sorption and desorption of moisture in epoxy composites reinforced with triangular and V-shaped bar fillers were studied. Epoxy was reinforced with vinyl ester bar assemblies fabricated according to 4 varied factors: bar orientation relative to diffusion direction (pointed or base side), bar alignment (parallel or staggered), spacing between bars (1 or 5 mm), and bar cross-sectional shape (triangular or V-shaped). Unlike previous studies, the bar fillers were initially coated with small amount of epoxy resin to improve wetting during fabrication of composites. Moisture uptake and loss of composites during one-side exposure to water vapor (50% relative humidity at 60°C) and hot air (60°C), respectively, were monitored with time. Experimental results show weight change of composites during moisture sorption and desorption varies linearly with square root of exposure time. Diffusion coefficients of composites were determined by assuming the material to be semi-infinite and fitting a mathematical solution to Fick’s second law of diffusion to weight change data. Results show diffusion coefficient of composites during moisture sorption is increased when bars are oriented pointed relative to diffusion direction, aligned parallel, spaced at 1 mm, and has triangular cross-sectional shape. However, during desorption, the diffusion coefficient is increased when base side of bars are exposed and when the bars are aligned staggered. The observed effects of factors on moisture diffusion coefficients of epoxy composites during sorption and desorption are discussed in relation to path length, available diffusion area, and status of epoxy/vinyl ester interphase before and after moisture sorption in composites.

MOISTURE DIFFUSION MODELING OF WHEAT KERNELS DURING SOAKING

1999 ◽  
Vol 42 (5) ◽  
pp. 1359-1366 ◽  
Author(s):  
S. Kang ◽  
S. R. Delwiche
Keyword(s):  
Moisture Diffusion ◽  
Diffusion Modeling ◽  
Wheat Kernels
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