Heat and mass transfer in a contaminated porous concrete slab subjected to microwave heating
Conference
Li, W, Ebadian, MA, White, TL et al. (1992). Heat and mass transfer in a contaminated porous concrete slab subjected to microwave heating
. American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD, 212 143-153.
Li, W, Ebadian, MA, White, TL et al. (1992). Heat and mass transfer in a contaminated porous concrete slab subjected to microwave heating
. American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD, 212 143-153.
Concrete decontamination using microwave technology is investigated theoretically in this paper. A one-dimensional, uniform plane wave is assumed for the microwave propagation and is employed to determine the microwave field and power dissipation within the concrete. Also, a one-dimensional model of unsteady heat and mass transport in the concrete is developed to evaluate the variations of temperature and pressure with heating time along the propagation direction by considering different microwave frequencies. The concrete is treated as a porous material in the theoretical analysis. During the heating process, heat and mass transfer due to microwave dissipation, and the evaporation of concrete residual water are considered. The effects of microwave frequency (f), microwave power intensity (Q0,ave), and concrete porosity (φ) on the microwave power dissipation (Qd,ave), temperature (T), and pressure (P0) distributions are considered in the present model. Four commonly used microwave frequencies of 0.896, 2.45, 10.6 and 18.0 GHz are used in the analysis. The results reveal that as the microwave frequency increases to, or higher than 10.6 GHz, all microwave power dissipation significantly shifts toward the front surface of the concrete. This implies that a proper selection of the microwave frequency can shift all microwave power dissipation to the thickness of radioactive contamination (z≤0.1 m). Furthermore, it is observed that by using a higher microwave frequency, power intensity requirements can be reduced. Therefore, use of a higher microwave power intensity can reduce the time it takes to break the concrete. Finally, the present analysis indicates that the effects of concrete porosity are negligible in concrete porosity ranges of 0.0 to 0.3.
