基于Wells-Riley方程分析实验室内水平气流对室内人员的感染风险*
摘要：
实验室作为半封闭空间,掌握气溶胶在其中的传播机制对理解呼吸道传染疾病的传播至关重要。本文使用Fluent软件模拟了不同新风工况对实验室内人体呼吸区域颗粒物分布的影响,并利用修正后的Wells-Riley方程估算了暴露者的感染概率。模拟结果表明:水平新风温度达到28 ℃时,高温度的新风从人体上方流过,有效规避了对呼吸区域的干扰,此时感染者对暴露者的感染概率为11.7%;当新风温度为24 ℃时,新风与感染者呼出气流相互作用,引发轨迹偏移,此时暴露者的感染概率降为10.6%;当新风温度为22 ℃时,较低温度的新风使得感染者的呼出气流向地板流动,因此暴露者的感染概率进一步降低至9.8%。通过研究矩形和圆形新风口工况,发现圆形新风口气流速度虽高,但穿透人体热边界层能力较弱,大部分气流绕过人体,对呼吸区域影响小,扰动程度低。比较相同温度下上送下回混合通风和水平通风工况,前者在呼吸区域易形成空气涡流,增加感染风险;后者则形成V形半封闭区,防止气流空间完全封闭,降低感染风险。
Abstract：
As a semi-enclosed space, mastering the transmission mechanism of aerosols in laboratories is crucial for understanding the spread of respiratory infectious diseases. This study uses Fluent software to simulate the impact of different outdoor air conditions on the particle distribution in the human breathing zone within laboratories, and employs a modified Wells-Riley equation to estimate the infection probability of exposed individuals. The simulation results show that when the horizontal outdoor air temperature reaches 28 ℃, the high-temperature outdoor air flows over the human body, effectively avoiding interference with the breathing zone, and the infection probability from the infected person to the exposed individual is 11.7% at this time. When the outdoor air temperature is 24 ℃, the interaction between the outdoor air and the exhaled airflow of the infected person causes trajectory deviation, and the infection probability of the exposed individuals decreases to 10.6%. When the outdoor air temperature is 22 ℃, the lower-temperature outdoor air causes the exhaled airflow of the infected person to flow toward the floor, thus the infection probability of the exposed individuals is further reduced to 9.8%. By investigating the conditions of rectangular and circular outdoor air outlets, it is found that although the air velocity of the circular outdoor air outlet is higher, its ability to penetrate the human thermal boundary layer is weaker, with most of the airflow bypassing the human body, resulting in little impact on the breathing zone and low disturbance degree. Comparing the mixed ventilation with upper supply and lower return and horizontal ventilation under the same temperature, the former is prone to forming air eddies in the breathing zone, increasing the infection risk. The latter forms a V-shaped semi-enclosed area, preventing complete closure of the airflow space and reducing the infection risk.
Keywords:laboratory; respiratory infectious diseases; horizontal airflow temperature; Wells-Riley equation; infection probability