Theory for Heat Transfer in Moist Porous Media
A moist porous medium is filled with moist air and liquid water. By making the local thermal equilibrium hypothesis for all phases (solid matrix, moist air and liquid water), The Heat Transfer in Moist Porous Media Interface solves for the following heat equation, obtained from Equation 4-41 by accounting for the liquid water phase in the definition of the effective material properties and in the convective heat flux:
(4-47)
(4-48)
The different quantities appearing here are:
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ρg and ρl (SI unit: kg/m3) the moist air and liquid water densities.
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Cp,g and Cp,l (SI unit: J/(kg·K)) the moist air and liquid water heat capacities at constant pressure.
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(ρCp)eff (SI unit: J/(m3·K)) the effective volumetric heat capacity at constant pressure defined by an averaging model to account for the solid matrix, the moist air, and the liquid water properties:
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where sl is the liquid water saturation.
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q the conductive heat flux (SI unit: W/m2).
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ug (SI unit: m/s) the moist air velocity field, that should be interpreted as the Darcy velocity, that is, the volume flow rate per unit cross sectional area.
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ul (SI unit: m/s) the liquid water velocity field, that should be interpreted as the Darcy velocity, that is, the volume flow rate per unit cross sectional area.
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keff (SI unit: W/(m·K)) the effective thermal conductivity (a scalar or a tensor if the thermal conductivity is anisotropic), defined by an averaging model to account for solid matrix, the moist air, and the liquid water properties. See Moist Porous Medium for details about the available averaging models.
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Q (SI unit: W/m3), defined as the sum of the diffusive flux of enthalpy and of the liquid capillary flux:
See Theory for Moisture Transport in Porous Media for the definition of gw and glc.
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Qevap (SI unit: W/m3) the heat source (or sink) due to water phase change, defined as:
See Theory for Moisture Transport in Porous Media for the definition of Gevap.