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Transient model for coupled heat, air and moisture transfer through multilayered porous media
The thermal and moisture dynamic responses of building enclosures, essential inputs for whole building hygrothermal models, have strong impact on the overall performance of the building. This is due to the fact that the moisture stored in the structure affects the indoor humidity and energy flow across the structure, and thereby HVAC equipment size. Moreover, building enclosures can have significant influence on the indoor humidity level depending on the moisture buffering capacity of the interior lining materials. The dynamic influences of building enclosures on the indoor environment and HVAC systems can be captured by using a transient model that handles coupled heat, air and moisture transfer through multilayered porous media. In this paper, a transient heat, air and moisture transfer model is developed based on basic conservation of mass and energy equations. The governing partial-differential equations (PDEs) of the three transport phenomena are coupled and solved simultaneously for temperature, relative humidity and pressure. The model accommodates nonlinear transfer and storage properties of materials, moisture transfer by vapor diffusion, capillary liquid water transport and convective heat and moisture transfer through multilayered porous media. The PDEs are derived in such a way that each PDE is described with a single driving potential, which is continuous across the interfaces of adjoining materials. Consequently, an equation-based modeling technique, which requires less time of implementation and provides high degree of transparency and flexibility of modeling, is used for solving the coupled PDEs. The transient HAM (Heat, Air, Moisture) model is successfully benchmarked against three published test cases. The test cases are comprised of an analytical verification, comparisons with other models and validation of simulation results with experimental data. The good agreement obtained with the respective test cases suggest that the model development and implementation are satisfactory, and therefore, can be further coupled with an indoor model to create a whole building hygrothermal model. The development and benchmarking of a holistic model that utilizes the transient model developed in this paper as one of its building block will be presented in subsequent paper.
Transient model for coupled heat, air and moisture transfer through multilayered porous media
The thermal and moisture dynamic responses of building enclosures, essential inputs for whole building hygrothermal models, have strong impact on the overall performance of the building. This is due to the fact that the moisture stored in the structure affects the indoor humidity and energy flow across the structure, and thereby HVAC equipment size. Moreover, building enclosures can have significant influence on the indoor humidity level depending on the moisture buffering capacity of the interior lining materials. The dynamic influences of building enclosures on the indoor environment and HVAC systems can be captured by using a transient model that handles coupled heat, air and moisture transfer through multilayered porous media. In this paper, a transient heat, air and moisture transfer model is developed based on basic conservation of mass and energy equations. The governing partial-differential equations (PDEs) of the three transport phenomena are coupled and solved simultaneously for temperature, relative humidity and pressure. The model accommodates nonlinear transfer and storage properties of materials, moisture transfer by vapor diffusion, capillary liquid water transport and convective heat and moisture transfer through multilayered porous media. The PDEs are derived in such a way that each PDE is described with a single driving potential, which is continuous across the interfaces of adjoining materials. Consequently, an equation-based modeling technique, which requires less time of implementation and provides high degree of transparency and flexibility of modeling, is used for solving the coupled PDEs. The transient HAM (Heat, Air, Moisture) model is successfully benchmarked against three published test cases. The test cases are comprised of an analytical verification, comparisons with other models and validation of simulation results with experimental data. The good agreement obtained with the respective test cases suggest that the model development and implementation are satisfactory, and therefore, can be further coupled with an indoor model to create a whole building hygrothermal model. The development and benchmarking of a holistic model that utilizes the transient model developed in this paper as one of its building block will be presented in subsequent paper.
Transient model for coupled heat, air and moisture transfer through multilayered porous media
Transientes Modell für die gekoppelte Übertragung von Wärme, Luft und Feuchtigkeit durch mehrschichtige poröse Stoffe
Tariku, Fitsum (author) / Kumaran, Kumar (author) / Fazio, Paul (author)
International Journal of Heat and Mass Transfer ; 53 ; 3035-3044
2010
10 Seiten, 16 Bilder, 1 Tabelle, 22 Quellen
Article (Journal)
English
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