Moisture buffering effect of hygroscopic materials under wall moisture transfer

2020 ◽  
pp. 1420326X2097583
Author(s):  
Ming Yang ◽  
Fanhong Kong ◽  
Xuancheng He
Keyword(s):  
Moisture Transfer ◽  
Buffering Capacity ◽  
High Moisture ◽  
Buffering Effect ◽  
Hygroscopic Material ◽  
The Difference ◽  
Room Model ◽  
Interior Finish ◽  
Moisture Buffering ◽  
Humidity Environment

Hygroscopic material can moderate the indoor humidity variation due to its moisture buffering effect. This effect would change when used as interior finish mainly due to air exchange and wall moisture transfer. The author focused on clarifying the extent of the wall'’s influence on indoor moisture buffering and building humidity environment. A room model was established and the situation of no wall moisture transfer was simulated by adding a vapour barrier between the interior finish and the wall. Comparing this result with wall moisture transfer, the moisture buffering effect of the wall can be quantitatively analysed. The results verify that the buffering effect and the humidity environment, especially the seasonal buffering, change with the wall moisture transfer. The wall has great impacts on buffering in the cases of thin interior finish, high moisture production and low ventilation. Because the layer under the hygroscopic material also has buffering capacity, the difference of using various thicknesses of material is not obvious. Frequent ventilation reduces the buffering effect but improves the RH optimality.

Waste-based geopolymeric mortars with very high moisture buffering capacity

2018 ◽  
Vol 191 ◽  
pp. 39-46 ◽  
Author(s):  
A. De Rossi ◽  
J. Carvalheiras ◽  
R.M. Novais ◽  
M.J. Ribeiro ◽  
J.A. Labrincha ◽  
...  
Keyword(s):  
Buffering Capacity ◽  
High Moisture ◽  
Moisture Buffering ◽  
Very High

scholarly journals Numerical Network Modeling of Heat and Moisture Transfer through Capillary-Porous Building Materials

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1819
Author(s):  
Borys Basok ◽  
Borys Davydenko ◽  
Anatoliy M. Pavlenko
Keyword(s):  
Building Materials ◽  
Moisture Transfer ◽  
Three Dimensional ◽  
Total Pore Volume ◽  
Equivalent Diameter ◽  
Average Pore ◽  
The Difference ◽  
Three Dimensional Coordinate ◽  
Solid Liquid ◽  
Heat And Moisture

The article presents the modeling of the dynamics of the vapor-gas mixture and heat and mass transfer (sorption-desorption) in the capillary structure of the porous medium. This approach is underpinned by the fact that the porous structure is represented by a system of linear microchannels oriented along the axes of a three-dimensional coordinate system. The equivalent diameter of these channels corresponds to the average pore diameter, and the ratio of the total pore volume to the volume of the entire porous material corresponds to its porosity. The entire channel area is modeled by a set of cubic elements with a certain humidity, moisture content, pressure and temperature. A simulation is carried out taking into account the difference in temperatures of each of the phases: solid, liquid and gas.

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 An Experimental Study on the Drying-Out Ability of Highly Insulated Wall Structures with Built-In Moisture and Rain Leakage

2019 ◽  
Vol 9 (6) ◽  
pp. 1222 ◽  
Author(s):  
Klaus Viljanen ◽  
Xiaoshu Lu
Keyword(s):  
Energy Efficient ◽  
Moisture Transfer ◽  
Mineral Wool ◽  
Rain Event ◽  
Controversial Issues ◽  
Wall Structures ◽  
Hygrothermal Performance ◽  
The Difference ◽  
Wood Frame ◽  
Heat And Moisture

The recent research on highly insulated structures presents controversial conclusions on risks in moisture safety. This paper addresses these controversial issues through investigating the hygrothermal performance of energy efficient envelope structures under high moisture loads. The experiments consist of built-in moisture and rain leakage tests in mineral wool insulated structures. A heat and moisture transfer simulation model is developed to examine the drying-out ability in both warm and cold seasons. The results show that the energy efficient structures have an excellent drying out ability against built-in and leakage moisture. The difference in the drying ability is limited compared to conventional structures. A critical leakage moisture amount reaching the insulation cavity for a wood frame wall is determined to be between 6.9–20.7 g in a single rain event occurring every other day. Further research is required to target highly insulated structures, particularly addressing water vapor diffusion and convection.

Hygrothermal Behavior of Thermal Insulating Material Based on Technical Hemp and its Application in Construction

2013 ◽  
Vol 860-863 ◽  
pp. 1223-1226
Author(s):  
Jiri Zach ◽  
Jitka Peterková ◽  
Martin Sedlmajer
Keyword(s):  
Building Materials ◽  
Moisture Absorption ◽  
Moisture Transfer ◽  
Natural Fibers ◽  
High Moisture ◽  
Building Envelopes ◽  
Thermal Insulating ◽  
Energy Demands ◽  
Hygrothermal Behavior ◽  
Heat And Moisture

Natural insulation materials have great potential of development given the contemporary requirements of the society in terms of reducing the energy demands of the production of building materials and the reduction of CO2emissions. Natural fibers are characteristic by their high moisture absorption and combustibility. The paper describes the results of research in the field of heat and moisture transfer within the structure of insulating materials based on natural fibers (hemp). The results of the experiments provided input data for computational simulations of hygrothermal behavior of hemp based fiber insulation applied in building envelopes.

Sign in / Sign up

Export Citation Format

Share Document