Study of Moisture Buffering in Building Materials with Application of Sorption Kinetics Models

2010 ◽  
Vol 297-301 ◽  
pp. 1232-1237 ◽  
Author(s):  
N.M.M. Ramos ◽  
João M.P.Q. Delgado ◽  
V.P. de Freitas
Keyword(s):  
Building Materials ◽  
Moisture Absorption ◽  
Stationary Process ◽  
Sorption Kinetics ◽  
Temperature Level ◽  
Kinetics Models ◽  
Buffer Value ◽  
Experimental Values ◽  
Moisture Buffering ◽  
Moisture Buffer Value

This work presents experimental values of Moisture Buffer Value (MBV) obtained with three different samples of building materials, using a non-stationary process of moisture absorption. The tests carried out at the laboratory tried to explore the importance of some of the variables that can interfere in the final results, such as materials themselves, temperature level and the use of finishing coatings. The experimental data obtained at 15°C and 23°C were then analyzed using the second order sorption kinetic model. The application of kinetics models to the experimental results was explored and several parameters were retrieved. A proposal for the use of these parameters is presented and its practical use is discussed.

scholarly journals A mathematical model for predicting the indoor moisture variation by using moisture buffering theory

2021 ◽  
Vol 2069 (1) ◽  
pp. 012036
Author(s):  
Kan Zu ◽  
Menghao Qin
Keyword(s):  
Mathematical Model ◽  
Energy Consumption ◽  
Indoor Air ◽  
Building Materials ◽  
Air Humidity ◽  
Acceptable Solution ◽  
Moisture Variation ◽  
Buffer Value ◽  
Moisture Buffering ◽  
Moisture Buffer Value

Abstract Indoor air humidity evaluation plays an of great importance role on the thermal comfort and building energy consumption. The utilization of hygroscopic materials as building materials acts on the indoor air humidity by regulating its humidity fluctuations, and then reduces a certain fraction of energy consumption on the air conditioning systems. Based on the Fick’s law, the physical process inside these hygroscopic materials requires the determinations of hygrothermal properties, which signify the extensive and reiterative experiments. While in many building simulation toolboxes, moisture buffering behavior has been evaluated by either simple approximations or complicated heat and mass model. In this case, we developed a mathematical model about the moisture transport with acceptable solution time and accuracy in terms of the moisture buffer value (MBV) theory. Considering that MBV originally represents the moisture buffering capacity of those hygroscopic materials, we did some mathematical deduction about MBVs under different boundary conditions. Then the definition of time-average MBV has been used, and all the required parameters was obtained from the practical MBV test. By comparing the new moisture buffer value model (MBM) with HAMT model, the results indicated that MBM could provide reasonably accurate prediction for indoor moisture variation.

scholarly journals Moisture Buffering of Multilayer Internal Wall Assemblies at the Micro Scale: Experimental Study and Numerical Modelling

2019 ◽  
Vol 9 (16) ◽  
pp. 3438 ◽  
Author(s):  
Dobrosława Kaczorek
Keyword(s):  
Penetration Depth ◽  
Buffering Capacity ◽  
Internal Wall ◽  
Simplified Method ◽  
Buffer Value ◽  
Series Of Experiments ◽  
Overall Performance ◽  
Wall Assembly ◽  
Moisture Buffering ◽  
Moisture Buffer Value

In this paper, a series of experiments assessing the moisture buffer value (MBV) of four internal wall assembly samples made from hygroscopic materials was performed. A modified Nordtest protocol was used. Moisture buffer values of all the investigated wall assemblies, with varying moisture loads in the range of 50% to 80%, showed a moderate moisture buffer value (MBV: 0.5–1.0 (g·m−2·%RH−1)). The results showed that in a wall assembly where the MBV of the whole assembly is lower than the MBV of the outer layers, the moisture-buffering capacity of the inner layer is untapped. Outer layers affect inner layers by changing their moisture-buffering capacity, which in turn changes the overall performance of the whole assembly. In addition, it was observed that if the penetration depth value of the outer layer is greater than its thickness, vapour reaches into the deeper layer and wall assemblies made of layers with materials characterized by a lower value of penetration depth reach steady state more slowly. The WUFI Pro tool was used to compare the simulated and experimental results. Despite the discrepancies between these results, it offers a simplified method, helping designers make decisions about which materials to choose to improve the moisture-buffering effect.

scholarly journals Moisture Buffer Value of Building Materials

2009 ◽  
pp. 33-33-12
Author(s):  
Carsten Rode ◽  
Ruut Peuhkuri ◽  
Berit Time ◽  
Kaisa Svennberg ◽  
Tuomo Ojanen
Keyword(s):  
Building Materials ◽  
Buffer Value ◽  
Moisture Buffer Value

scholarly journals Moisture Buffer Value of Building Materials

2007 ◽  
Vol 4 (5) ◽  
pp. 100369 ◽  
Author(s):  
Carsten Rode ◽  
Ruut Peuhkuri ◽  
Berit Time ◽  
Kaisa Svennberg ◽  
Tuomo Ojanen ◽  
...  
Keyword(s):  
Building Materials ◽  
Buffer Value ◽  
Moisture Buffer Value

scholarly journals The Effects of Natural Paint on the Moisture Buffering Ability of Paper Plaster

2020 ◽  
Vol 57 (5) ◽  
pp. 51-60
Author(s):  
N. Nutt ◽  
A. Kubjas ◽  
L. Nei ◽  
A. Ruus
Keyword(s):  
Relative Humidity ◽  
Indoor Air ◽  
Waste Paper ◽  
Moisture Permeability ◽  
Daily Variations ◽  
Number Of Layers ◽  
Buffer Value ◽  
Moisture Buffering ◽  
Moisture Buffer Value

AbstractThe scope of the Nordtest method is to evaluate the moisture buffer value (MBV) of materials exposed to indoor air. The test is intended to simulate daily variations with relative humidity (RH) between 75 % during 8 hours and 33 % during 16 hours.The specimens follow a recipe that consists of waste paper, glue and water. Specimens made of paper plaster were covered with different colours.The results of the experiment showed that the type of paint used and the number of layers applied affected the MBV. Natural colours have a better moisture permeability than chemical paints, but the number of natural colour layers affects the MBV. The higher the number of layers, the lower the MBV.

Measurement of Diffusion Coefficients in Building Materials Using the Initial Rate of Sorption

2006 ◽  
Vol 258-260 ◽  
pp. 85-90
Author(s):  
João M.P.Q. Delgado
Keyword(s):  
Diffusion Coefficient ◽  
Relative Humidity ◽  
Building Materials ◽  
Molecular Diffusion ◽  
Moisture Absorption ◽  
Molecular Diffusion Coefficient ◽  
Different Types ◽  
Uniform Manner ◽  
Experimental Values ◽  
Good Agreement

This work presents experimental values of molecular diffusion coefficient, obtained with samples of building materials, using a non-stationary process of moisture absorption. The experiments covered four different types of building materials (with two selected ranges of relative humidity) and were carried out in the range of temperatures between 20°C and 40°C. The results show that the increase in temperature resulted in an increase in molecular diffusion coefficient and the relative humidity also influenced the molecular diffusion in a uniform manner. Finally, a good agreement with literature values was found.

scholarly journals Numerical Simulation of Water Absorption and Swelling in Dehulled Barley Grains during Canned Porridge Cooking

Processes ◽  
2018 ◽  
Vol 6 (11) ◽  
pp. 230 ◽  
Author(s):  
Lei Wang ◽  
Mengting Wang ◽  
Mingming Guo ◽  
Xingqian Ye ◽  
Tian Ding ◽  
...  
Keyword(s):  
Moisture Absorption ◽  
Three Dimensional ◽  
Processing Conditions ◽  
Relative Deviation ◽  
Cooking Process ◽  
Proposed Model ◽  
Hygroscopic Swelling ◽  
3D Numerical Model ◽  
Barley Grains ◽  
Experimental Values

Understanding the hydration behavior of cereals during cooking is industrially important in order to optimize processing conditions. In this study, barley porridge was cooked in a sealed tin can at 100, 115, and 121 °C, respectively, and changes in water uptake and hygroscopic swelling in dehulled barley grains were measured during the cooking of canned porridge. In order to describe and better understand the hydration behaviors of barley grains during the cooking process, a three-dimensional (3D) numerical model was developed and validated. The proposed model was found to be adequate for representing the moisture absorption characteristics with a mean relative deviation modulus (P) ranging from 4.325% to 5.058%. The analysis of the 3D simulation of hygroscopic swelling was satisfactory for describing the expansion in the geometry of barley. Given that the model represented the experimental values adequately, it can be applied to the simulation and design of cooking processes of cereals grains, allowing for saving in both time and costs.

scholarly journals PECULIARITIES OF KINETICS OF THE COEFFICIENT OF THERMAL CONDUCTIVITY DEPENDING ON THE HUMIDITY RATE OF WALL BLOCKS MADE OF AGRICULTURAL WASTES

2019 ◽  
Vol 4 (10) ◽  
pp. 19-28 ◽  
Author(s):  
А. Должонок ◽  
A. Dolzhonok ◽  
А. Бакатович ◽  
A. Bakatovich
Keyword(s):  
Thermal Conductivity ◽  
Building Materials ◽  
Moisture Absorption ◽  
Coarse Aggregate ◽  
Sustainable Use ◽  
Agricultural Wastes ◽  
Hygroscopic Moisture ◽  
Relative Air Humidity ◽  
Coefficient Of Thermal Conductivity ◽  
Kinetics Of

The article considers the prospect of plant wastes usage as aggregates while constructing new building materials in the form of wall blocks. The results of the research on water absorption of the wall blocks at the relative air humidity of 97 % are presented. The kinetics of change in humidity and the coefficient of thermal conductivity of the blocks with the rye and buckwheat straw coarse aggregate, and also the blocks with fine coarse aggregate of flax boon and atomized buckwheat are analyzed. Empirical dependences of the coefficient of thermal conductivity on the rate of humidity of wall blocks are obtained from experimental observations. After the maximum rate of hygroscopic moisture absorption, the best indexes are recorded on the blocks made of flax and straw. The humidity rate of the composite does not exceed 10,9 % with the increase of thermal conductivity up to 0.104 W/(m•°С). In the result of the research, the solution to the sustainable use of agricultural wastes to get environmental responsible building materials is proposed. Blocks can be are used in the erection of supporting and filler walls in one-story buildings and multistoried frame housing construction when filling exterior wall openings.

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