The Experts below are selected from a list of 6711 Experts worldwide ranked by ideXlab platform
Robert Cerný - One of the best experts on this subject based on the ideXlab platform.
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effect of Moisture Content on heat and Moisture transport and storage properties of thermal insulation materials
Energy and Buildings, 2012Co-Authors: Milos Jerman, Robert CernýAbstract:Abstract Computational models of heat and Moisture transport are frequently used in calculating energy gains and losses in buildings. However, any model can provide reliable information only in the case that the quality of input data is adequate. This is not always true because the standard lists of thermal and hygric parameters given by the producers as well as the material databases included in the simulation tools are usually far from complete. In this paper, we present the measurements of complete sets of heat and Moisture transport and storage parameters of selected thermal insulation materials in dependence on Moisture Content. Two common thermal insulation materials, namely hydrophobic mineral wool and expanded polystyrene, are selected as reference materials. Two types of hydrophilic mineral wool and an autoclaved-aerated-concrete thermal insulation board are the representatives of prospective materials which appeared on the market within the last couple of years. The studied material parameters include bulk density, matrix density, porosity, Saturation Moisture Content, thermal conductivity, specific heat capacity, Moisture diffusivity, water vapor diffusion coefficient, sorption isotherm, and water retention curve.
Katell Derrien - One of the best experts on this subject based on the ideXlab platform.
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the effect of applied stresses on the equilibrium Moisture Content in polymers
Scripta Materialia, 2007Co-Authors: Katell DerrienAbstract:The relation between Saturation Moisture Content in a polymer and applied stresses is derived as a function of the coefficient of Moisture expansion. The model is applied to the equilibrium water uptake of an isotropic polymer matrix composite. It is shown that a composite has a nonlinear sorption isotherm even though the matrix has a linear one, because of the internal stresses induced by swelling.
Milos Jerman - One of the best experts on this subject based on the ideXlab platform.
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effect of Moisture Content on heat and Moisture transport and storage properties of thermal insulation materials
Energy and Buildings, 2012Co-Authors: Milos Jerman, Robert CernýAbstract:Abstract Computational models of heat and Moisture transport are frequently used in calculating energy gains and losses in buildings. However, any model can provide reliable information only in the case that the quality of input data is adequate. This is not always true because the standard lists of thermal and hygric parameters given by the producers as well as the material databases included in the simulation tools are usually far from complete. In this paper, we present the measurements of complete sets of heat and Moisture transport and storage parameters of selected thermal insulation materials in dependence on Moisture Content. Two common thermal insulation materials, namely hydrophobic mineral wool and expanded polystyrene, are selected as reference materials. Two types of hydrophilic mineral wool and an autoclaved-aerated-concrete thermal insulation board are the representatives of prospective materials which appeared on the market within the last couple of years. The studied material parameters include bulk density, matrix density, porosity, Saturation Moisture Content, thermal conductivity, specific heat capacity, Moisture diffusivity, water vapor diffusion coefficient, sorption isotherm, and water retention curve.
Stanley J. Vitton - One of the best experts on this subject based on the ideXlab platform.
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Analysis of drying and saturating natural gypsum samples for mechanical testing
Elsevier, 2019Co-Authors: Mohammadhossein Sadeghiamirshahidi, Stanley J. VittonAbstract:The stability of underground abandoned gypsum mines is dependent on the gypsum pillar's strength, and most abandoned mines are in a fully saturated condition. Moisture affects the strength of gypsum and is therefore commonly measured when testing rock strength. For most rocks, this is a simple task of weighing the rock's mass before and after oven-heating at a specified temperature and duration. For natural gypsum, however, this is not a straightforward process. Heating natural gypsum can result in dehydration and transformation of gypsum to hemihydrate and anhydrite, thus changing the physical characteristics of the gypsum such as its particle density which in turn affects the Moisture Content and strength measurements. To prevent transformation when determining the Moisture Content of gypsum, the American Society for Testing Materials (ASTM) recommends lowering the drying temperature from 110 °C to 60 °C. To investigate the temperature at which gypsum transforms to hemihydrate, we used a helium pycnometer to measure the particle densities of gypsum, hemihydrate and anhydrite. In this research, we suggest that a higher drying temperature of 80 °C can be used for drying gypsum without transforming gypsum to hemihydrate. Further, preparing saturated samples for mechanical testing, which is required in stability analyses of abandoned mines, is challenging due to the dissolution of gypsum when placed in water. To address this problem, we investigated the following methods to saturate gypsum cores taking into account the solubility of gypsum: (1) water immersion, (2) vacuum Saturation, and (3) improved vacuum Saturation. The research indicates that all the three methods are acceptable but they should be conducted using a saturated gypsum-water solution to minimize dissolution. Further, the research found that the improved vacuum Saturation method saturated the test samples within 24 h, while duration of 30 h was required for the other two methods. Keywords: Gypsum-hemihydrate-anhydrite transformation, Dehydration, Rock core Saturation, Moisture Content, Helium pycnomete
Silvio Jose Gumiere - One of the best experts on this subject based on the ideXlab platform.
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development of a steady state model to predict daily water table depth and root zone soil matric potential of a cranberry field with a subirrigation system
Agricultural Water Management, 2019Co-Authors: Yao Bigah, Alain N Rousseau, Silvio Jose GumiereAbstract:Abstract Maintaining a steady water table depth (WTD) to ensure an optimal soil matric potential in the root zone (RMAP) is vital when growing cranberry under a subirrigation system; owing to losses and other hydrological processes. The excessive rising or falling of the WTD may threaten the plant transpiration either by Saturation or lack of Moisture in the root soil. A steady-state model was developed for a uniform soil column to predict WTD and RMAP under different weather conditions. The model is based on van Genuchten (VG) and Brooks and Corey (BC) analytical soil water retention functions coupled with Mualem, Brooks and Corey, and Gardner hydraulic conductivity models. The results show that the model is capable of predicting satisfactorily both WTD and RMAP. The VG model performed with a 78.13% accuracy for the WTD and an 88.59% precision according to the Kling Gupta Efficiency coefficient (r2 = 0.90, β = 1.00, and γ = 0.99) for the field storage. Meanwhile for the RMAP the Mualem and Gardner hydraulic conductivity models, predictions were successful 71.87% and 75.00% of the time, respectively. The BC model had a 78.13% success for the WTD, 86.93% accuracy in estimating the field water storage according to Kling-Gupta efficiency coefficient (r2 = 0.89, β = 1.00, and γ = 1.00) and the BC and Gardner hydraulic conductivity models had 65.63% and 71.88% success, respectively. A sensitivity analysis of the model, by means of the Morris method, reveals that for both models, the lower boundary condition impacts significantly both variables which are, however, less affected by the field capacity and the residual soil Moisture Content. The lower boundary condition interacts with the slope of the soil water retention functions, the height of the capillary fringe, the saturated conductivity, and the Saturation Moisture Content which have non-linear effects. An uncertainty analysis shows that both variables for both models are normally distributed.
