Research On Ventilation Mode Control And Optimization Based On Adaptability Of Indoor Air Quality And Fresh Air Energy Consumption

With the development of modern science and technology and the improvement in people’s quality of life,indoor air quality is of more and more concern.Ventilation is usually an effective way to improve indoor air quality,but this may also cause an increase in energy consumption in both summer and winter.In this study,the indoor air quality represented by ozone and PM2.5 along with air-conditioning energy consumption were studied in depth through two methods of experimental measurement and software simulation.In the experimental part of the study,the PM2.5 concentration,the ozone concentration,and the air change rates in 24 typical residential buildings in Nanjing were measured and analyzed.The analysis of the experimental results showed that the air change rate of the room with the window open was about 8 times higher than the air change rate with the window closed.For ozone,the order of concentration in building environment was the following: outdoor concentration > indoor concentration when the window was open > indoor concentration when the window was closed.It can be concluded that the ozone in the indoor environment came from outdoors.In winter,the outdoor ozone concentrations were generally low,followed by the transition season,and in summer,the outdoor ozone concentration was higher.There was also a significant difference in different building floor height.The higher the floor was,then the greater the outdoor ozone concentration was.However,different seasons and floor heights had little effect on indoor ozone concentration when the window was closed.For PM2.5,the concentrations with the window being open or closed were similar,and the average values under the three conditions were not significantly different.From this,it can be inferred that PM2.5 pollution sources exist both indoors and outdoors.The outdoor concentrations of PM2.5 in summer were low,but in winter and transition seasons were high.The indoor and outdoor concentration of PM2.5 decreased in the higher floors,but the decrease was not significant.The indoor concentrations of pollutants increased gradually with the increase in outdoor concentrations,and the rate of increase was reflected in the I / O ratio.The I / O ratio of ozone and PM2.5 increased with the increase of air change times and decreased with the increase of the deposition rate.For PM2.5,when the I / O ratio of PM2.5 was 0.96,the deposition velocity and resuspension velocity were equal.In the simulation part,the Open Modelica platform was mainly used to simulate and analyze the natural ventilation with fixed window openings(0%,25%,50%,75%,100%)along with the natural ventilation with PID(proportional integral derivative)control to optimize the window opening and the mechanical ventilation with PID control for fan operation in summer and winter.For the natural ventilation with fixed window openings,the larger the window opening was,then the greater the air change rate was,and the faster the ozone reached the outdoor ozone concentration level.However,the PM2.5 concentration was getting relatively low because indoor pollution sources were generated,and ventilation was more effective in removing pollutants.The energy consumption of fresh air in the room increased with the increase of window openings.The fresh air energy consumption of the fully open window was nearly 49 times as much as that of the fully closed window.For the natural ventilation with PID control to optimize the window opening,the control curve of the window opening had vibration.According to five kinds of fixed window opening,this study did some de-vibration optimization.The results showed that the optimized window opening indoor air quality and fresh air energy consumption are in a relatively ideal state.Compared to the natural ventilation,the mechanical ventilation has larger air change rate,in the study,it reached as much as 16 times per hour.The indoor air quality was better than the natural ventilation,but the energy consumption increased especially when pollutants released.The total fresh air energy consumption increased by 20-30 times compared with that when the window was fully closed,and decreased by 30%-40% compared with that when the window was fully opened.When the window opening requirements of indoor ozone and PM2.5 conflicted,it was recommended to open windows appropriately under the condition that the ozone concentration did not exceed the standard.When the indoor ozone concentration reached the limit value,the windows should be closed completely according to the ozone demand.In winter,the outdoor PM2.5 concentration in Nanjing was high,and the ideal indoor air quality couldn’t not be achieved only by ventilation,so it was recommended to use air purifier.When using the indoor air purifier,it was better to close the window completely,because it could reduce the exchange of indoor clean air and outdoor air,and maximized the efficiency of the air purifier.In this model,the coarse effect filter can meet the requirements of the national first-class standard.If we want to further reduce the indoor pollutant concentration,the effect of medium high efficiency filter and sub high efficiency filter were not very different.The whole thesis contains about 59 000 words,80 pictures and charts.