Influence of Temperature, Enclosure and Ventilation on Radon Concentration Distribution in a Blind Roadway

doi:10.19596/j.cnki.1001-246x.8295

Abstract

Abstract:

With computational fluid dynamics and physical properties of radon, a three-dimensional steady-state transport model of radon in a blind roadway with a chamber is established. The control equation is calculated with software Fluent. Radon exhalation and decay in the inner wall of the roadway are realized with UDF. Wind field structure and radon concentration distribution in roadway are obtained. It shows that when the ventilation rate is constant, temperature has a significant effect on radon concentration. The higher the temperature in the roadway, the higher the radon concentration in the roadway. Radon concentration of the chamber is the greatest in the whole roadway. Compared with radon prevention enclosure, local ventilation is better for reducing radon. As pressure ventilation is adopted, radon concentration in the roadway increases from inside to outside.Improving ventilation rate of the tunnel reduces effectively radon concentration at the entrance of the tunnel, while it has little effect on radon concentration in the chamber.

Key words: radon, numerical simulation, ventilation, temperature

CLC Number:

O368

Zhankang YANG, Yi NIU. Influence of Temperature, Enclosure and Ventilation on Radon Concentration Distribution in a Blind Roadway[J]. Chinese Journal of Computational Physics, 2021, 38(4): 456-464.

Figures/Tables 16

References 22

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材料	密度/(kg·m^-3)	摩尔质量/(g·mol^-1)	导热系数/(w·m^-1·K)	粘性系数/(pa·s)^[16]	比热容/(J·kg^-1·K)
空气	1.225	29	0.024 2	1.789 8×10^-5	1 006.43
氡	9.73	222	0.003 6	1.8×10^-5	96.33

材料	密度/(kg·m^-3)	摩尔质量/(g·mol^-1)	导热系数/(w·m^-1·K)	粘性系数/(pa·s)^[16]	比热容/(J·kg^-1·K)
空气	1.225	29	0.024 2	1.789 8×10^-5	1 006.43
氡	9.73	222	0.003 6	1.8×10^-5	96.33

工况	风机送风口A	巷道入口	巷道内壁	温度/℃	巷道内壁氡析出率/(Bq·s^-1·m^-2)	氡的扩散系数/(cm²·s^-1)
Case 1	为速度入口，风速为8 m·s^-1，氡的组分设置为0，湍动能为3.57 %，特征长度为0.3 m	采用自然出流出口边界条件	设置为壁面，且壁面无滑移，绝热	20	0.140 1	0.032 8
Case 2				25	0.184 1	0.045 3
Case 3				30	0.228 1	0.057 8

工况	风机送风口A	巷道入口	巷道内壁	温度/℃	巷道内壁氡析出率/(Bq·s^-1·m^-2)	氡的扩散系数/(cm²·s^-1)
Case 1	为速度入口，风速为8 m·s^-1，氡的组分设置为0，湍动能为3.57 %，特征长度为0.3 m	采用自然出流出口边界条件	设置为壁面，且壁面无滑移，绝热	20	0.140 1	0.032 8
Case 2				25	0.184 1	0.045 3
Case 3				30	0.228 1	0.057 8

工况	风机送风口A	风机送风口B /(m·s^-1)	巷道入口	巷道内壁	温度/℃	巷道内壁氡析出率/(Bq·s^-1·m^-2)	氡的扩散系数/(cm²·s^-1)
Case 1~3	设置为速度入口，风速均为8 m·s^-1，氡的组分设置为0，湍动能为3.57 %，特征长度为0.3 m	0.1	采用自然出流出口边界条件	设置为壁面，且壁面无滑移，绝热	20 25 30	0.140 1 0.184 1 0.228 1	0.032 8 0.045 3 0.057 8
Case 4~6		0.3
Case 7~9		0.5
Case 10~12		1