Investigation And Optimization Analysis Of Indoor Air Environment In Xi'an Heating Season Dormitory

As a pance of college shudents living and restingin danily life,the indoor air quality ofdormitory is closely related to students' physical and mental health and learning effieiency.Withthe high density of persormel and poor ventilartion,the bad air quality In dormitory is more worrying than that of ordinary residential buildings.Especially in seasonswhenthe lemperature difTerence between indoor and outdoor is large and the outdoor air pollution is serious,poor ventilation is easy to cause the spread and diffusion of infeetious diseases through the air.Firstly the thesis elaborates the thearies relalted to indoor air environment.Secondly taking the dormitory if a university in Xi'an as the research object,the study understands the present situation of indoor air environment in the heating season through the questionaire survey and field measurement,which identifies the main problems and main air pollutanta.Then the indoor pollution is evaluated by gray correlation analysis and the typical indoor air environment model of dormitory is csCablished and verified by the Fluent numerical simulation softwant,After the simulation and analysts of the degree of opening window,pre-ventilation time and other conditions,the scheme of improving the indoor air environment under the natural ventilationisobtained.Finally the study uses CONTAM to simulate the influenee of environmental equipment schemes such as air purifierand the fresh air filiration sysrem on indoor air environment.Bassed on that,the optiization mesaures of improving the indoor air quatity under line purificalion of air purifier and mechanical vertilation are proposed.The research results are as follows(1)through the monitoring survey of incdoor temperature,humidity,CO2 concentration,PM10 canceritration,TVOC coneentration and the cobneentration of formaldehyde in 30 dormitories of Xi'an in the heating season,the author found that indoor temperature,TVOC concentration and the concentration of formaldehyde all meet the requirements of relevant standards but the concentrations of humidity,CO2 and PM10exceed the standard limits.Besides as the main indoor air pollutants,the excess multiple of concentration of CO2 and PM10is pretty high.After the detection of indoor air quality in morning,afternoon and evening,the indoor air qualityis the worst at night.But only 5%of dormitoriesopen windows to ventilate.The questionnaire shows indoor persons feel that dormitories aretoo hot,dry and uncomfortable,which accounts for 58.7%,75.8%,and 89.8%respectively.Some students think that the bad indoor air quality is mainly caused by the poor ventilation.All dormitories monitored are under the light pollution by the analysis and evaluation of gray theory.(2)The modeling and analysis of typical dormitory environment by Fluent show that the indoor environmental parameters change with time and the degree of opening window when the dormitory is continuously ventilated at a window opening rate of 3cm,5cm,7cm,9cm and 11cm at night.The indoor air environment can be effectively optimized when the window is opened for 7cm.Under this condition,indoor temperature and humidity can meet the requirements of relevant standards and achieve the the best comfort level after the calculation of PMV value.The concentrations of CO2 and PM10 also reach the allowable limits of relevant standards when the window is opened within 1 and 2 hours respectively.What's more when the window is opened for 40cm for 10 minutes,20 minutes and 30 minutes respectively before students go to bed at night,theCO2 concentration and humidity can meet the relevant standards.However,the concentration of PM10 exceeds the standard under the influence of outdoor pollution.Therefore,the natural ventilation with opening window for 7cm can comprehensively optimize indoor air quality.But the pre-ventilation can only effectively reduce the concentration of indoor CO2 pollutants in a short time,which is of little significance for optimizing indoor air quality.(3)The modeling and analysis on typical dormitory environment by CONTAM presents that when the air purifier reached at 30m3/h stipulated by relevant standards,indoor PM10 concentration can be effectively reduced but the CO2 concentration can not be reduced.Fresh air filtration system can effectively reduce the concentrations of indoor CO2 and PM10.When the system is switched on and the volume of air supply is 150m3/h or above,the concentrations of indoor CO2 and PM10 are both up to the standard.Therefore,the indoor air environment quality can be comprehensively and effectively optimized when the fresh air filtration system is adopted and the volume of air supply is 150m3/h.