Moisture Transport in Wood-Based Structural Panels under Transient Hygroscopic Conditions

2020 ◽  
Vol 70 (3) ◽  
pp. 283-292
Author(s):  
Daniel Way ◽  
Frederick A. Kamke ◽  
Arijit Sinha
Keyword(s):  
Moisture Transport ◽  
Transport Model ◽  
Oriented Strand Board ◽  
Primary Objective ◽  
Accelerated Weathering ◽  
Wood Composite ◽  
Transport Parameters ◽  
Moisture Profile ◽  
Cyclic Changes ◽  
Wood Based Composite

Abstract Development of moisture gradients within wood and wood-based composites can result in irreversible moisture-induced damage. Accelerated weathering (AW), generally employing harsh environmental conditions, is a common tool for assessing moisture durability of wood composite products. Use of milder AW conditions, such as cyclic changes in relative humidity (RH), may be of interest to the wood-based composites industry in assessing moisture durability under more realistic conditions. The primary objective of this study was to determine whether moisture profile development in oriented strand board and plywood during cyclic RH changes could be reasonably predicted with a simple moisture transport model, which may be practical for wood-based composite industry members seeking to develop new AW protocols. The diffusion model based on Fick's second law with empirically determined moisture transport parameters fits the experimental data reasonably well for the purpose of screening RH parameters.

Moisture Transport Model for Enhancing FHWA HIPERPAV Predictions

2009 ◽  
Vol 2113 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Qinwu Xu ◽  
J. Mauricio Ruiz ◽  
George K. Chang ◽  
Robert O. Rasmussen ◽  
Dan K. Rozycki
Keyword(s):  
Moisture Transport ◽  
Transport Model

scholarly journals Comparison of three stream tube models predicting field-scale solute transport

1997 ◽  
Vol 1 (4) ◽  
pp. 873-893 ◽  
Author(s):  
D. Jacques ◽  
J. Vanderborght ◽  
D. Mallants ◽  
D.-J. Kim ◽  
H. Vereecken ◽  
...  
Keyword(s):  
Solute Transport ◽  
Transport Model ◽  
Local Scale ◽  
Transfer Model ◽  
Transport Parameters ◽  
Field Scale ◽  
Stream Tube ◽  
Solute Dispersion ◽  
Measurement Volume ◽  
Piston Flow

Abstract. In this paper the relation between local- and field-scale solute transport parameters in an unsaturated soil profile is investigated. At two experimental sites, local-scale steady-state solute transport was measured in-situ using 120 horizontally installed TDR probes at 5 depths. Local-scale solute transport parameters determined from BTCs were used to predict field-scale solute transport using stochastic stream tube models (STM). Local-scale solute transport was described by two transport models: (1) the convection-dispersion transport model (CDE), and (2) the stochastic convective lognormat transfer model (CLT). The parameters of the CDE-model were found to be lognormally distributed, whereas the parameters of the CLT model were normally distributed. Local-scale solute transport heterogeneity within the measurement volume of a TDR-probe was an important factor causing field-scale solute dispersion. The study of the horizontal scale-dependency revealed that the variability in the solute transport parameters contributes more to the field-scale dispersion at deeper depths than at depths near the surface. Three STMs were used to upscale the local transport parameters: (i) the stochastic piston flow STM-I assuming local piston flow transport, (ii) the convective-dispersive STM-II assuming local CDE transport, and (iii) the stochastic convective lognormal STM-III assuming local CLT. The STM-I considerably underpredicted the field-scale solute dispersion indicating that local-scale dispersion processes, which are captured within the measurement volume of the TDR-probe, are important to predict field-scale solute transport. STM-II and STM-III both described the field-scale breakthrough curves (BTC) accurately if depth dependent parameters were used. In addition, a reasonable description of the horizontal variance of the local BTCs was found. STM-III was (more) superior to STM-II if only one set of parameters from one depth is used to predict the field-scale solute BTCs at several depths. This indicates that the local-scale solute transport process, as measured with TDR in this study, is in agreement with the CLT-hypothesis.

Influence of Cultivar on the Predictive Performance of a Moisture Transport Model Developed for Parboiled Paddy Drying

2013 ◽  
Vol 31 (5) ◽  
pp. 494-506 ◽  
Author(s):  
Lovelyn N. Onuoha ◽  
Ndubisi A. Aviara ◽  
Toyin A. Abdulrahim ◽  
Ahmed T. Suleiman
Keyword(s):  
Moisture Transport ◽  
Transport Model ◽  
Predictive Performance

Evaluating Chemical Toxicity of Surface Disposal of LILW-SL in Belgium

2008 ◽  
Vol 1107 ◽  
Author(s):  
D. Mallants ◽  
L. Wang ◽  
E. Weetjens ◽  
W. Cool
Keyword(s):  
Transport Model ◽  
Chemical Elements ◽  
Near Field ◽  
Distribution Coefficients ◽  
Small Scale ◽  
Transport Parameter ◽  
Chemical Toxicity ◽  
Transport Parameters ◽  
Field Environment ◽  
Waste Container

AbstractONDRAF/NIRAS is developing and evaluating a surface disposal concept for low and intermediate level short-lived radioactive waste (LILW-SL) at Dessel, Belgium. In support of ONDRAF/NIRAS's assignment, SCK•CEN carried out long-term performance assessment calculations for the inorganic non-radioactive components that are present in LILW-SL. This paper summarizes the results obtained from calculations that were done for a heavily engineered surface disposal facility at the nuclear zone of Mol/Dessel. The calculations address the migration of chemotoxic elements from the disposed waste to groundwater.Screening calculations were performed first to decide which non-radioactive components could potentially increase concentrations in groundwater to levels above the groundwater standards. On the basis of very conservative calculations, only 6 out of 41 chemical elements could not be classified as having a negligible impact on man and environment. For each of these six elements (B, Be, Cd, Pb, Sb, and Zn), the source term was characterized in terms of its chemical form (i.e., metal, oxide, or salt), and a macroscopic transport model built that would capture the small-scale dissolution processes relevant to element release from a cementitious waste container. Furthermore, reliable transport parameters in support of the convection-dispersion-retardation (CDR) transport calculations were determined. This included derivation of (1) solubility for a cementitious near field environment based on thermodynamic equilibrium calculations with The Geochemist's Workbench, and (2) distribution coefficients based on a compilation of literature values. Scoping calculations illustrated the effects of transport parameter uncertainty on the rates at which inorganic components in LILW-SL leach to groundwater.

Properties of Cement Composites Containing Coir Pith

2014 ◽  
Vol 982 ◽  
pp. 136-140 ◽  
Author(s):  
Eva Vejmelková ◽  
Dana Koňáková ◽  
Anna Krojidlová ◽  
Veronika Hovorková ◽  
Monika Čáchová ◽  
...  
Keyword(s):  
Moisture Transport ◽  
Building Materials ◽  
Agricultural Waste ◽  
Cement Matrix ◽  
Cement Composites ◽  
Coir Fiber ◽  
Transport Parameters ◽  
Coir Pith ◽  
Adhesion Ability ◽  
Mechanical Strengths

Application of agricultural waste materials as building materials not just provides solutions of environmental problems related to the waste management, but it also decreases the use of limited available natural resources and energy. The research in this work is focused on using coconut waste, in the form of natural and chemically treated coir pith, as admixture partially replacing cement in cement composites. The coir pith is the residue acquired during the extraction coir fiber from the outer protective husk of the coconut. Basic physical properties, mechanical, thermal and hygric parameters of several mixtures were studied. The results of measurements showed the influence of amount of coconut addition primarily on parameters such as the bulk density, open porosity, mechanical strengths, moisture transport parameters and thermal parameters. Restrictions for utilization of this waste material relate primarily with its low adhesion ability to the cement matrix.

scholarly journals Hydrodynamic dispersion characteristics of lateral inflow into a river tested by a laboratory model

2009 ◽  
Vol 13 (2) ◽  
pp. 217-228 ◽  
Author(s):  
P. Y. Chou ◽  
G. Wyseure
Keyword(s):  
Pore Water ◽  
Transport Model ◽  
Column Experiment ◽  
Breakthrough Curves ◽  
Water Velocity ◽  
Laboratory Model ◽  
Hydrodynamic Dispersion ◽  
Transport Parameter ◽  
Transport Parameters ◽  
Pore Water Velocity

Abstract. Groundwater and river-water have a different composition and interact in and below the riverbed. The riverbed-aquifer flux interactions have received growing interest because of their role in the exchange and transformation of nutrients and pollutants between rivers and the aquifer. In this research our main purpose is to identify the physical processes and characteristics needed for a numerical transport model, which includes the unsaturated recharge zone, the aquifer and the riverbed. In order to investigate such lateral groundwater inflow process, a laboratory J-shaped column experiment was designed. This study determined the transport parameters of the J-shaped column by fitting an analytical solution of the convective-dispersion equation for every flux on individual segments to the observed breakthrough curves of the resident concentration, and by inverse modelling for every flux simultaneously over the entire flow domain. The obtained transport-parameter relation was tested by numerical simulation using HYDRUS 2-D/3-D. Four steady-state flux conditions (i.e. 0.5 cm hr−1, 1 cm hr−1, 1.5 cm hr−1 and 2 cm hr−1) were applied, transport parameters including pore water velocity and dispersivity were determined for both unsaturated and saturated sections along the column. Results showed that under saturated conditions the dispersivity was fairly constant and independent of the flux. In contrast, dispersivity under unsaturated conditions was flux dependent and increased at lower flux. For our porous medium the dispersion coefficient related best to the quotient of the pore water velocity divided by the water content. A simulation model of riverbed-aquifer flux interaction should take this into account.

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