某便利店内颗粒物分布特征与运动规律仿真分析

Simulation analysis on the distribution characteristics and movement rules of particulate matter in a convenience store

目的建立特定场所基于时间变化的颗粒物空间分布模型,分析颗粒物的时空分布特征与变化趋势。方法选择某便利店为研究对象,检测场所环境微小气候和颗粒物数量浓度(PNC),采用计算流体动力学(CFD)仿真方法进行数值模拟,基于离散相模型分析仿真颗粒物的时空分布特征与运动规律。结果便利店进口的风速较低且在检测时长内几乎无变化,而外侧和内侧出风口的风速较高且变化剧烈。便利店室内各检测点粒径为0.02~1.00μm的PNC均高于粒径>1.00μm者(P值均<0.05);粒径为0.02~1.00μm的PNC由高到低依次为收银台、进口、外侧出风口和内侧出风口(P值均<0.05);收银台与进口位置PNC变化幅度较大,而外侧和内侧出风口位置PNC变化相对平稳。CFD仿真结果显示,人员在便利店进口附近的收银台所呼出的颗粒物受气流影响可更快地排出室外;而当人员位于货架中间时所呼出的颗粒物在室内悬浮运动的时间长于位于收银台时;处于空调出风口散发的颗粒物于300 s内扩散到便利店全部空间并达到稳态。结论便利店内的颗粒物以小粒径颗粒物(<1.00μm)为主。人呼出颗粒物的停留时间、下降趋势和悬浮颗粒物数量等与气流组织相关,空调逸散的颗粒物可迅速扩散至便利店几乎全部空间。

Objective The spatial distribution model of particulate matter based on time change in a specific place was established to analyze the spatial and temporal distribution characteristics and movement of particulate matter.Methods A convenience store was selected as the research subject.The micro-climate and particle number concentration(PNC)of the site were detected,and numerical simulation was carried out by computational fluid dynamics(CFD)simulation method.Based on the discrete phase model,the temporal and spatial distribution characteristics and movement rules of simulated particles were analyzed.Results The wind speed at the entrance of the convenience store was low and almost unchanged during the detection,while the wind speeds outside and inside outlets were high and changed sharply.The PNC of particle size of 0.02-1.00μm was higher than that of particle size>1.00μm(all P<0.05).The PNC with particle size of 0.02-1.00μm from high to low were checkout counter,entrance,outer outlet and inner outlet(all P<0.05).The PNC of the checkout counter and entrance varies greatly,while the PNC of the outer outlet and inner outlet was relatively steady.The CFD simulation results showed that particles exhaled by individuals near the entrance of the checkout counter of the convenience store could be expelled outdoors more quickly with the influence of airflow.However,particles exhaled by individuals in the middle of the shelves remained suspended indoors for a longer period of time compared to those near the checkout counter.Particles emitted from the air conditioning outlet diffuse throughout the entire store and reach a steady state in 300 seconds.Conclusion The particulate matter in the convenience store was mainly small particle with the size less than 1.00μm.The residence time,downward trend and number of suspended particulates of human exhaled particles were related to air flow.The particulates escaped from the air conditioner could quickly spread to almost the entire convenience store.