Study On The Variation Regulation And Control Technology Of Indoor Fine Particulate Matter In Civil Building

In recent years, with the improvement of people's living standard, the demand for the human settlement has become higher and higher. People all over the world pay close attention to destruction of fine particulate matter to human health and atmospheric environment. Indoor air environment is of great importance in people's life and work environment. Modern people spend more than 80% of time in a day in indoor environment. However, indoor air environment is not always safe. Outdoor fine particulate matter can enter room through various ways, while indoor pollution sources also produce fine particulate matter. Indoor pollution may be more serious than that of outdoor environment when there is no effective control measure. So the study of variation and control technology of indoor fine particulate matter has become an urgent task.Most current experimental studies consider interaction of penetration and deposition, but different experimental conditions lead to great difference in results. The author carries out real-time monitoring to mass concentration of indoor fine particular matter in well-sealed room, analyzes variation regulation of indoor PM2.5 concentration according to experimental data, and obtains variation characteristic of indoor PM2.5 under different particulate source concentrations. Experimental results indicate that concentration change of indoor fine particulate concentration shows the same rules under the presence of indoor particulate pollution sources. PM2.5 concentration can quickly rise to the highest value in a short period, then curve down, and become stable after precipitation. When indoor fine particulate matter increases, indoor PM2.5 concentration becomes higher. It requires longer time to precipitate. When the particulate source concentration is 1000?g/m3, 2000?g/m3 and 3000?g/m3 respectively, the average precipitation time is 7 hours, 30 hours and 49 hours.Most of the existing precipitation models are based on the impact of various factors on the concentration of fine particulate matter, while there are few studies emphasizing on the precipitation property of indoor particles, and the precipitation rate can't be directly obtained. This paper establishes static precipitation model of indoor fine particulate matter in sealed room, and gains average precipitation rate under different conditions. The calculated results of the static precipitation prediction model are consistent with the experimental results, which indicate that the static precipitation model is more reliable. We can know from model analysis that the precipitation of indoor fine particulate matter in sealed room can be divided into rapid precipitation stage, slow precipitation stage and stable stage, and indoor PM2.5 concentrations shows linear change in the rapid precipitation stage, exponential change in slow precipitation stage, and a stable value in stable stage. When the particulate source concentration is 1000?g/m3, 2000?g/ m3 and 3000?g/m3, the average precipitation rate is 0.36 h-1, 0.09 h-1 and 0.08 h-1.Natural ventilation control technology has great influence on concentration change of indoor PM2.5. When outdoor air quality is good, ventilation can improve indoor air quality, but structure of windows and wall will affect the natural ventilation effect. This paper carries out experimental study on natural ventilation control of indoor PM2.5 pollution, and simulates and analyzes the effect of different window positions on indoor PM2.5 concentration by using CFD software. The experimental results show that the natural ventilation will greatly reduce the highest concentration value of indoor PM2.5 when outdoor air quality is good by accelerating the diffusion and precipitation of indoor PM2.5. The average precipitation time is reduced to 1.5 hours, 2 hours and 3 hours when the particulate source concentration is 1000?g/m3, 2000?g/m3 and 3000?g/m3. The analysis of simulation results indicate that the removal rate of indoor particulate matter is the highest when the window is located at the opposite side of the door, which is more than 1.5 times compared with no windows on the opposite wall.The control method of natural ventilation has limitation, when outdoor fine particulate matter pollution concentration is higher, outdoor fresh air will also bring in particulate pollutants, which would affect indoor air quality. This paper conducts engineering detection to construction with central ventilation system and purification control technology. We add purification plants with various functions on central ventilation unit, and make experimental study on its purification performance. By testing outdoor concentration of fine particulate matter in the process of central ventilation and purification, the author gains purification efficiency of multifunctional central ventilation under different conditions. The experimental results show that when outdoor air quality is good, the central ventilation unit can apply low and medium efficient filter, and its average purification efficiency is 83.4%; when outdoor air quality is poor, its average purification efficiency is 82.9% by using low and medium efficient filter with first grade electrostatic depuration; its average purification efficiency is 89.3% when applying low and medium efficient filter with second grade electrostatic depuration. When there exists indoor pollution source, multifunctional central ventilation unit can effectively maintain good indoor air quality with indoor air purifier, which is the most effective purification method.