Research On Control Of Indoor Air Microbial Pollution By Outdoor Air System For High Density People Building

Indoor air quality is closely related to people’s physical and mental health.The emission of indoor pollution sources and the infiltration of outdoor air pollutants will lead to indoor air pollution and affect people’s health.The outdoor air system is an effective measure to control indoor air pollution.It introduces the purified outdoor fresh air into the room,dilutes the concentration of indoor air pollutants and improves the indoor air quality of buildings.This paper takes high-density buildings as the research object,adopts the method of combining testing and simulation to study the control effect of outdoor air system on indoor air microorganism pollution,and then analyzes the control effect and influencing factors of outdoor air system.First of all,taking the example of school construction project with outdoor air system as the research object,taking the opening time of outdoor air system and other parameters as the influencing factors of the control effect of outdoor air system,the control effect of indoor air microbial concentration is tested and researched.The test analysis found that after 1.5 hours of opening the outdoor air system,the centralized and household three-stage filter outdoor air systems have a good control effect on bacteria and fungi in the indoor air.Classified according to room function area,the outdoor air system purification effect of bacterial from high to low:classroom,office,activity room,the outdoor air system purification effect of fungus from high to low:classroom,office,activity room;with the extension of the opening time of the outdoor air system,the concentration of bacteria and fungi in the indoor air gradually decreases;bacteria in the indoor air.It is distributed in particle size of other grades except Grade III.Fungi are mainly distributed in Grade V.To some extent,there is a difference between indoor air microbial particle size distribution and outdoor.The significant related factors of bacterial concentration in indoor air are outdoor air bacterial concentration,outdoor air rate,air change rate,and the significant factors related to fungal concentration in indoor air are outdoor air rate,air change rate,functional area,room area and room type.Secondly,taking the indoor air quality of school buildings as the research object,consider testing the bacteria and fungi pollution in the indoor air of different functional areas under the condition of indoor people staying to evaluate the indoor air quality.Test analysis found that the initial concentration of bacteria and fungi in the indoor air is related to the functional area of the room when the room is unoccupied and the doors and windows are closed.The degree of bacteria and fungus contamination from high to low is:dormitory,laboratory,classroom;there were 4 subjects in the room who remained sitting and working for 3 hours,the bacterial concentration in the indoor air of the laboratory,dormitory and classroom increased by 163.33%、70.42%和375.01%,respectively,and the per capita bacterial release was 64.19 CFU/m~3,81.67CFU/m~3 and98.25CFU/m~3;analysis of indoor air microbial concentration and related influencing factors found that the significant related factors of indoor air bacterial concentration are functional area and personnel staying status,and the significant related factors of indoor air fungal concentration are function area.Finally,taking the classroom of school building as an example,the application of Fluent simulation,under different personnel density and personnel bacteria amount,the outdoor air system on indoor bacteria control effect of simulation research.Simulation results show that with the increase of the density of people and the increase of the outdoor air rate of the room,when the indoor people are in static activities,,the indoor bacterial cleaning rates of large,medium and small classrooms were 90.90%～92.36%,92.81%～94.15%and 94.76%～95.18%.The average cleaning rate of bacteria in large,medium and small classrooms decreased by 8.52%,9.77%and 7.61%,respectively,after the personnel activity state changed from static to dynamic,indicating that the room with personnel activity could appropriately increase the outdoor air rate.The bacterial cloud map showed that after the outdoor air system was purified,the activity state of personnel changed from static to dynamic,and the concentration of indoor bacteria increased and the distribution range of bacteria became wider.On the whole,with the increase of human density and outdoor air rate,and the indoor bacteria concentration and distribution change is not obvious.The outdoor air system has a certain effect on the treatment of indoor air bacteria,only in the pollution sources,walls and corners of the wall there are still a little bacteria retained.