Research On Air Quality And Ventilation Simulation Of University Classrooms In Cold Winter Regions

With the continuous development of economy,the concentration of various pollu-tants in the atmosphere increases gradually,and the problem of environmental pollution becomes more and more serious.People spend most of their time indoors,so indoor air quality is more important than atmospheric environment.As an important place for stu-dents to study,university classrooms must provide enough fresh air to meet health and health requirements.But in our country,the teaching buildings in Colleges and univer-sities basically adopt the form of natural ventilation.On the one hand,the intermittent open-door and open-window ventilation can not solve the problem of insufficient fresh air,which leads to the excessive concentration of carbon dioxide in the classroom.On the other hand,it will make the pollutants in the atmosphere flow into the room with the air,especially in winter.Improving indoor air quality has become an urgent problem.In this paper,a multi-regional network simulation software CONTAMW is used to build a software model based on a typical public teaching building in a university in Tianjin.Then,five public teaching buildings were selected to test the indoor CO₂ and PM_2.5 concentration during the class period.The simulation results were compared with the measured data to verify the reliability of the model.And the measured data of indoor CO₂ and PM_2.5 concentration under different windows and doors were analyzed to eval-uate the air quality in the classroom of colleges and universities in winter.The validated software model is used to analyze the impact of building structure?including the floor,size,window height and interior doors and windows of the class-room?and meteorological factors?including outdoor temperature,wind speed,wind direction?on classroom CO₂ concentration and ventilation.According to the research,the concentration of CO₂ and PM_2.5 in winter classroom is easy to exceed the standard.Even though the behavior of intermittent door opening and window opening can alle-viate the phenomenon of CO₂ concentration exceeding the standard caused by insuffi-cient fresh air to a certain extent,it will also introduce particulate pollutants in the at-mosphere into the room.And it is recommended to add a mechanical fresh air system.Finally,the economic analysis of the mechanical fresh air system of the teaching build-ing is carried out from two aspects of initial investment and operation cost.The initial investment of boiler and ground source heat pump as heat source is 1.104 million yuan and 2.65 million yuan respectively,but the operation cost of ground source heat pump is lower and it has long-term economic advantages.