Research On Dynamics Model And Control Of Radon Migration Within Double Layer Medium

Radon is a kind of radioactive gas,under high radon concentration environment for a long time can increase the risk of inducing lung cancer.Currently,the research on indoor radon migration mainly focused on discussing the variation of radon concentration in the air domain with steady-state conditions as well as some research on analyzing the control or reduce radon concentration measures and obtaining the variation of radon concentration rely on time using experimental method in closed buildings.However,the study on non-steady state characteristics of the radon concentration on double-layer porous medium is deficient.The research works of this paper are used by the methods of experimental study and numerical simulation.The main contents of this paper as following:(1)Using Comsol software to discuss the effect of outdoor radon concentration,porosity of porous medium,diffusion coefficient,and thickness of porous medium on the distribution of radon concentration and the surface radon exhalation rate with a two-dimensional double-layer porous media migration model.(2)Using RAD7 to monitor the change of radon concentration and obtain the radon concentration accumulation curve of the double-layer building materials sample,and compare with simulation result to verify the three-dimensional indoor radon concentration accumulation model.Two kinds of covering materials(gypsum,oligomer),and three cover thickness(10mm,20 mm,30mm)and four environment temperatures(20?,23?,26?,29?)were measured.The accumulation of concentration was monitored to calculate the value of the surface exhalation rate with different conditions.(3)A room with the size of 10m×5m×3.4m combined with built-in wall was established by the method of CFD numerical simulation.Multiple impact parameters,including air supply velocity(0.1m/s,0.2m/s,0.3m/s,0.4m/s,0.5m/s),air supply mode,the thickness of porous media,diffusion coefficient and porosity were considered by non-steady numerical simulation to explore the dynamic variation rules of indoor radon concentration.