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Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Combined heat, air and moisture (HAM) transfer model for porous building materials
A combined HAM transport model for consolidated porous building materials has been presented. The model considers the vapor pressure, the air pressure (moist air), and the temperature gradients as driving potentials of the HAM transfer through building porous structures. Those potentials can be considered continuous at the interfaces between different porous materials, unlike the common seen moisture content and capillary suction pressure gradients. Another limitation found in some mathematical models is neglecting the air transport. The three driving potential distributions for a two-layer wall have been simultaneously obtained using the MTDMA (MultiTriDiagonal-Matrix Algorithm) to solve the set of discretized governing equations, considering a fully implicit central difference scheme. Despite the solution is more timeconsuming due to the presence of three strongly coupled set of equations, the algorithm has shown itself to be a very effective solver even under the presence of highly nonlinear transport coefficients. Results have been presented showing the convective transport impact on the relative humidity and temperature profiles within a wall composed of insulation and brick layers. The dominant effect of the convective vapor flow on the total moisture transport has also been noticed. Although the air permeability has been considered constant, nonconstant air permeabilities associated to air pressure driving potentials could have been used. The real need to introduce new methods for material characterization has been described by Bomberg et al. (2002). Therefore, for a more rigorous analysis of the combined HAM transport through porous building materials, international efforts to created detailed material property data base - considering variables transport coefficients at high relative humidity values, including air relative permeability for the correct airflow prediction - is still a great need for the applicability of current computer codes.
Combined heat, air and moisture (HAM) transfer model for porous building materials
A combined HAM transport model for consolidated porous building materials has been presented. The model considers the vapor pressure, the air pressure (moist air), and the temperature gradients as driving potentials of the HAM transfer through building porous structures. Those potentials can be considered continuous at the interfaces between different porous materials, unlike the common seen moisture content and capillary suction pressure gradients. Another limitation found in some mathematical models is neglecting the air transport. The three driving potential distributions for a two-layer wall have been simultaneously obtained using the MTDMA (MultiTriDiagonal-Matrix Algorithm) to solve the set of discretized governing equations, considering a fully implicit central difference scheme. Despite the solution is more timeconsuming due to the presence of three strongly coupled set of equations, the algorithm has shown itself to be a very effective solver even under the presence of highly nonlinear transport coefficients. Results have been presented showing the convective transport impact on the relative humidity and temperature profiles within a wall composed of insulation and brick layers. The dominant effect of the convective vapor flow on the total moisture transport has also been noticed. Although the air permeability has been considered constant, nonconstant air permeabilities associated to air pressure driving potentials could have been used. The real need to introduce new methods for material characterization has been described by Bomberg et al. (2002). Therefore, for a more rigorous analysis of the combined HAM transport through porous building materials, international efforts to created detailed material property data base - considering variables transport coefficients at high relative humidity values, including air relative permeability for the correct airflow prediction - is still a great need for the applicability of current computer codes.
Combined heat, air and moisture (HAM) transfer model for porous building materials
Kombiniertes Hitze-, Luft- und Feuchtigkeitsübertragungsmodell (HAM) für poröse Baumaterialien
Santos, Gerson Henrique dos (Autor:in) / Mendes, Nathan (Autor:in)
Journal of Buildings Physics ; 32 ; 203-220
2009
18 Seiten, 9 Bilder, 2 Tabellen, 26 Quellen
Aufsatz (Zeitschrift)
Englisch
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