Numerical Analysis Of Coupled Heat And Mass Transfer Phenomena In Concrete At Elevated Temperatures

Based on well-established physical laws, a one-dimensional model that describes coupled heat and mass transfer phenomena in heated concrete has been developed. The mathematical model is based on the fully implicit finite difference scheme. The control volume approach was employed in the formulation of the finite difference equations. The primary variables considered in the analysis are temperature, vapor density, and pore pressure of the gaseous mixture. Several phenomena have been taken into account, such as evaporation, condensation, and dehydration processes. Temperature-, pressure-, and moisture content-dependent properties of both gaseous and solid phases were also considered. Numerical case studies that deal with extremely rapid heating of concrete are validated against experimental results with good agreement in spatial and temporal trends for temperature and pressure. Outputs from the numerical model demonstrated the influence of the coupling relationship between heat and mass transfer phenomena on temperature, vapor, and pressure distributions. Furthermore, it was noted that the temperature distribution trends are significantly affected by the vapor migration phenomenon; such an effect becomes more pronounced when moving deeper toward the concrete core