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

Borys Basok,Anatoliy M Pavlenko,Borys Davydenko

doi:10.3390/ma14081819

Borys Basok, Anatoliy M Pavlenko + Show 1 more

Open Access

https://doi.org/10.3390/ma14081819

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Journal: Materials	Publication Date: Apr 7, 2021
Citations: 8	License type: CC BY 4.0

Affiliation: Kielce University of Technology

Abstract

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.

Highlights

Most of the materials used in construction have a capillary-porous structure
Many computational schemes use models based on the phenomenological theory of mass and heat transfer [1,2,3], whereby a real porous structure is replaced by a homogeneous continuous medium
Equivalent diameters of these channels correspond to the average pore diameter of the analyzed porous medium; a ratio of the total pore volume to the porous material volume corresponds to this material porosity

Summary

Introduction

Most of the materials used in construction have a capillary-porous structure. The thermal insulation properties of these materials depend on the condition parameters: temperature, pressure, humidity and moisture content. The transfer processes for this continuous medium are expressed by mass and energy conservation equations, where volume-averaged physical values and effective transfer coefficients are used [4,5,6,7] This approach is quite justified, as the shape of pores, their quantity and distribution in the material volume are random parameters, if we do not mean formed cracks in pore connecting interpore space or channel porosity. It is the channel porosity (cracks, as shown in Figure 1) that can significantly change thermophysical properties of the material In this case, averaging of physical values over material volume results in errors in the calculations of heat and mass transfer parameters

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Conclusion