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.

Development of a numerical approach to assess the effect of coupled heat and moisture transfer on energy consumption of residential buildings in Moroccan context

2021 ◽  
pp. 174425912110560
Author(s):  
Yassine Chbani Idrissi ◽  
Rafik Belarbi ◽  
Mohammed Yacine Ferroukhi ◽  
M’barek Feddaoui ◽  
Driss Agliz
Keyword(s):  
Energy Consumption ◽  
Building Materials ◽  
Moisture Transfer ◽  
Residential Buildings ◽  
Building Design ◽  
Energy Performance ◽  
Climatic Conditions ◽  
Heat And Moisture Transfer ◽  
Coupled Heat And Moisture ◽  
Heat And Moisture

Hygrothermal properties of building materials, climatic conditions and energy performance are interrelated and have to be considered simultaneously as part of an optimised building design. In this paper, a new approach to evaluate the energy consumption of residential buildings in Morocco is presented. This approach is based on the effect of coupled heat and moisture transfer in typical residential buildings and on their responses to the varied climatic conditions encountered in the country. This approach allows us to evaluate with better accuracy the response of building energy performance and the indoor comfort of building occupants. Annual energy consumption, cooling and heating energy requirements were estimated considering the six climatic zones of Morocco. Based on the results, terms related to coupled heat and moisture transfer can effectively correct the existing energy consumption calculations of the six zones of Morocco, which currently do not consider energy consumption due to coupled heat and moisture transfer.

scholarly journals Strain-Stress Formation and Deformation of Molded Materials by Drying-Induced Shrinkage

2018 ◽  
Vol 248 ◽  
pp. 01011
Author(s):  
Yoshinori Itaya
Keyword(s):  
Mass Transfer ◽  
Moisture Transfer ◽  
Three Dimensional ◽  
Internal Strain ◽  
Stress Generation ◽  
Heat And Moisture Transfer ◽  
Internal Heating ◽  
Strain Stress ◽  
Stress Formation ◽  
Heat And Moisture

Drying-induced strain-stress and deformation was modeled for molded materials such as ceramics and foods. The transient three-dimensional problem of strain-stress and heat and moisture transfer was solved simultaneously by the finite element method. The behaviors of internal strain-stress formation and deformation are compared among three modes of hot air heating, intermittent heating and internal heating for a ceramic slab. The concepts of the mass transfer potential and a linear viscoelasticity were introduced to consider the different sorption isotherm for layered foods consisting of two ingredients and creep phenomenon. The tensile and compressive stresses fluctuate and fall remarkably during lower heating period when the slab is heated intermittently. In the internal heating mode, drying proceeds fastest as well as stress formation is maintained at the lowest level in the three modes. This effectiveness of the internal heating is investigated experimentally by employing the microwave heating as well. The combination of different foods influences significantly not only the drying characteristic but also the internal strain-stress generation. The drying behavior could be analyzed with a high accuracy even if only heat and moisture transfer were solved without strain-stress analysis. This fact results in that heat and mass transfer and strain-stress are not always necessary to be analyzed simultaneously for saving the CPU time.

scholarly journals Numerical modelling of a hemp concrete wall

2019 ◽  
Vol 85 ◽  
pp. 08003 ◽  
Author(s):  
Georges Costantine ◽  
Chadi Maalouf ◽  
Tala Moussa ◽  
Guillaume Polidori ◽  
Elias Kinab
Keyword(s):  
Building Materials ◽  
Moisture Transfer ◽  
Numerical Study ◽  
Object Oriented ◽  
Hysteresis Phenomenon ◽  
Energy Costs ◽  
Concrete Wall ◽  
Heat And Moisture ◽  
Account Heat ◽  
Indoor And Outdoor

In a global warming context associated to the abuse of energy consumption, actual researches focus more and more on reducing energy costs in the building sector. This target could be achieved by using innovative building materials, such as hemp concrete, due to its positive impacts on thermal and environmental levels. The aim of this work is to carry out a numerical study of a hemp concrete wall subjected to several indoor and outdoor conditions of temperature and relative humidity using the program object oriented SPARK. The hygrothermal behaviour of the wall is investigated taking into account heat and moisture transfer within the wall as well as hysteresis phenomenon between the sorption and desorption curves and their temperature dependency.

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.

scholarly journals Assessment of Deterioration Risk of Maijishan Grotto under the Radiation Difference Based on Heat and Moisture Transfer Model

2021 ◽  
Vol 2069 (1) ◽  
pp. 012082
Author(s):  
R B Wu ◽  
Y Ma ◽  
H R Xie ◽  
S Hokoi ◽  
Y Q Yue ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Water Content ◽  
Moisture Transfer ◽  
Transfer Model ◽  
Two Dimensional ◽  
Architectural Heritage ◽  
Direct Sunlight ◽  
The Difference ◽  
The Buddha ◽  
Heat And Moisture

Abstract The ambient environment of architectural heritage is an important factor affecting its conservation. Two adjacent rows of Buddha statues in Grottoes No. 3 (semi-open) of Maijishan Grotto in Gansu, China, show apparent differences in the degree of deterioration. This study made a monitoring scheme of grottoes microenvironments such as air temperature, relative humidity, radiation, and surface temperature to explore the cause of the difference. A two-dimensional heat and moisture (HAM) transfer model was established and verified to simulate the temperature and humidity on the surface and inside of the Buddha statues. Then, temperature and water content fluctuation and the risks of thermal stress destruction on the surface and near the surface of the Buddha statues were evaluated. The results show that the radiation difference causes thermal stress and water content differences both in heights and in depths. This impact brought by the direct sunlight may contribute to the different deterioration on the two rows of Buddha statues. The eaves shaded the upper row of the Buddha statues much longer than the lower ones. Less severe fluctuation and differences in temperature and water content occur at the middle and upper points. This study evaluates the degradation of Grottoes No. 3 and has guiding significance for its preservation methods.

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