Research On Application Of Window Air Purifying Ventilator In Improving Primary School Classrooms' Ventilation

Indoor environment is very important space for people to live,study and work.Recent researches indicate that people spend 80%⁹0% of their lifetime in indoor environment and bad indoor air quality will damage people's health.School building is a special type of building.This kind of building often have high occupant density,long residence time of people and bad ventilation.Since most school buildings in China have no mechanical ventilation system and the atmospheric environment is suffering from severe pollution,school classroom is becoming a severely affected area by both indoor and outdoor pollution,especially for primary schools.Children in primary schools are still growing and developing;their immune system are still immature and they breathe more relative to body weight than adults,so bad indoor environment will bring more serious negative effect to their health.This thesis investigate the current situation of ventilation and indoor air quality in primary school classrooms by experimental research.And based on the investigation result,this thesis also studies how to use window air purifying ventilator as a solution to improve classroom's ventilation and indoor air quality.To investigate the current situation of ventilation and indoor air quality in primary school classrooms,this thesis choose two primary schools in Beijing to conduct experimental research.The ventilation rate,carbon dioxide concentration,PM2.5 mass concentration in indoor and outdoor environment,temperature and relative humidity are tested.The result shows that when windows and doors are closed,ventilation rates in classrooms are lower than 1l/s/p,which could not meet people's basic need for fresh air;and CO₂ concentration in classrooms could rise up from outdoor level to more than 2000 ppm in just on lesson.The result also indicate that whether the windows are open or closed,classrooms indoor air will suffer from outdoor PM2.5 pollution.This thesis research on using window air purifying ventilators as a kind of decentralized ventilation system to solve classroom's indoor air environment problems.By analyzing the experiment data in classroom,it is found that when ventilation rate is higher than 5l/s/p,the indoor CO₂ concentration will be lower than 1000 ppm.To limit indoor PM2.5 concentration in different area,air filters at level of F7^H10 by EN779 standard should be used in ventilators.Based on the target parameter,the cross-flow fan and air filters have been studied by experiment,CFD simulation and theoretical calculation method.Based on these studies,a prototype have been made and installed in laboratory to conduct further experiment.The performance of prototype ventilator have been tested and predicted by experiment and numerical simulation methods and also compared with other decentralized ventilation system.The result indicate that using window air purifying ventilator can supply sufficient fresh air to indoor environment as well as effectively control PM2.5 concentration in indoor air.Comparing to using natural ventilation plus air cleaner,window air purifying ventilator can achieve better indoor pollution controlling effect by less ventilation volume.