ISSN Online: 2377-424X
ISBN Print: 0-89116-299-2
International Heat Transfer Conference 7
EFFECTS OF HEAT FLUX ON THE MIGRATION OF MOISTURE IN A CYLINDRICAL CONCRETE TUBE
Abstract
In recent years, there has been considerable
interest in the physics of moisture movement in
porous media under the influence of a thermal
gradient. The knowledge of interactions of heat
and mass transfer in porous media is of great
importance in areas such as those of heat and
moisture transfer in thermal-insulation materials
and in concretes used for construction of nuclear
reactors.
Attempts to apply diffusion theory to the drying of concrete have not been successful. A major factor is that in using a diffusion theory the effect of a thermal gradient on the movement of moisture in concrete is excluded.
In the present study, the new mechanistic theory (developed by the writer using the principles of irreversible flows of heat and mass, the linear phenomenological relations, and the laws of conservation in continua) is applied to study the effects of heat flux on the moisture migration in a concrete tube. A set of basic equations, for heat and mass transport in the concrete tube, comprises three nonlinear partial differential equations and an empirical relation of sorption equilibrium for concrete. An implicit difference method is employed for obtaining numerical solutions.
The effects of heat flux upon the migration of moisture from the heated zone toward the unheated zone and the interactions of mass and heat transfer are discussed. Numerical results are compared qualitatively with published experimental results.
Attempts to apply diffusion theory to the drying of concrete have not been successful. A major factor is that in using a diffusion theory the effect of a thermal gradient on the movement of moisture in concrete is excluded.
In the present study, the new mechanistic theory (developed by the writer using the principles of irreversible flows of heat and mass, the linear phenomenological relations, and the laws of conservation in continua) is applied to study the effects of heat flux on the moisture migration in a concrete tube. A set of basic equations, for heat and mass transport in the concrete tube, comprises three nonlinear partial differential equations and an empirical relation of sorption equilibrium for concrete. An implicit difference method is employed for obtaining numerical solutions.
The effects of heat flux upon the migration of moisture from the heated zone toward the unheated zone and the interactions of mass and heat transfer are discussed. Numerical results are compared qualitatively with published experimental results.