Numerical simulation study on the radon exhalation mechanism of building walls influenced by coupled heat-moisture-air transfer

Abstract

Building materials are one of the main sources of indoor radon, study of radon exhalation from building walls is of great reference significance for indoor radiation protection. Radon exhalation from building walls is comprehensively affected by environmental factors. A radon migration and exhalation model of building walls under the influence of coupled heat-moisture-air transfer was established. The radon exhalation mechanism of an aerated concrete wall under the influence of different relative humidity, temperature, relative humidity difference, temperature difference, air pressure difference and solar radiation was studied. The sensitivity of these factors to radon exhalation rate was analyzed. The results showed that the radon exhalation rate was positively correlated with relative humidity, but not with temperature; The radon exhalation rate was positively correlated with the relative humidity difference, and the temperature affected the correlation degree; The radon exhalation rate was positively correlated with the absolute temperature difference, and the relative humidity affected the correlation degree; The exhalation rate of radon was approximately linearly positive correlated with the pressure difference; Under the influence of solar radiation, the radon exhalation rate decreased; Radon parameters of material, relative humidity and solar radiation were more sensitive to radon exhalation rate than temperature, air pressure and radon concentration in air. For reducing radon exhalation rate of building walls and indoor radon concentration, we propose to use building wall materials with low radium content, keep indoor relative humidity and indoor and outdoor temperature difference low, and strengthen indoor ventilation at night, cloudy and rainy days.