【作者】 何瑾；

【导师】 沈恒根；

【作者基本信息】 东华大学 ， 供热、供燃气、通风及空调工程， 2012， 硕士

【摘要】 居住环境空气质量与人体健康密切相关,而颗粒物是首要污染物,会携带各种病菌,在居住建筑室内设置空气净化器已势在必行。在颗粒物粒径分布广泛的场合使用滤料,存在滤网堵塞问题,致使滤料更换频繁,造成维护工作成本上升,高效低阻的过滤材料对于维护人体健康及节能有着重要的意义。本文以净化微粒用过滤材料为研究对象,寻找滤料过滤效率高,阻力低,容尘量大,寿命长的设计规律。首先,采用GRIMM型气溶胶监测仪等仪器对上海市某大学宿舍及居民楼的室外及室内人员活动(整理被褥)前后PMx的实际浓度及粒径分布状况进行了测试,发现PM10浓度瞬时值高于标准限值,且人员活动会导致10μm左右颗粒物激增,粒径分布呈双峰分布,在0.20～0.40μm与10μm左右处达到峰值。因此,有必要对居住环境进行自洁过滤,同时做到颗粒物“粗细兼收”,对人体健康及节能环保有着重要意义。测试常用预过滤材料及驻极体滤料对PM10分级过滤效率,得到颗粒物尺度、过滤速度、孔隙率及滤料纤维直径对滤料过滤效率的影响,结果表明驻极体滤料对各粒径范围均有较好的过滤效果,考虑到驻极体滤料的使用场合及重复使用问题,对比了几种溶液浸泡处理前后过滤分级效率,结果表明清洗后效率均大幅下降,说明静电效应是驻极体滤料高效低阻的原因,故其不适用于富含极性分子的场合。为了探究空气净化用清洁滤料结构参数对阻力的影响程度,搭建滤料阻力测试试验台,并对选定滤料进行测试,试验测试结果与理论计算结果对比发现需要对纤维的非均匀分布进行修正。同时,通过试验结果分析过滤速度、孔隙率、纤维细度及厚度对滤料阻力的影响,得出滤料结构参数影响阻力的关系式,由各参数影响滤料阻力的数值范围权重可以对清洁滤料的降阻起到指导作用。针对空气净化器滤料预过滤与主过滤材料布置方式及两层滤料叠加的复合滤料折叠型布置方式,采用数值模拟方法对比了不同孔隙率条件下滤层截面的阻力分布与气流速度场,计算其速度场不均匀度,结果表明,气流速度场不均匀度与阻力有关；复合滤料具有阻力低、均匀容尘特点,解决了滤料易堵塞问题。通过调整滤料的织物层状构造和滤层结构,采用滤料内层分层分尺度积尘替换现有滤层表层积尘,解决滤料表面滤饼造成阻力上升过快问题和预过滤、主过滤两级串联带来的设备空间问题。对外层大容尘量低阻滤料、内层高效驻极体滤料复合的过滤材料性能分析可知其有对细小颗粒物高效过滤的特点,同时阻力增加的幅度在10%以内。更多还原

【Abstract】 The air quality in residential environment is closely related to human health. Particulate matters are the primary pollutant, carrying various bacteria. Setting up indoor air purifier is now imperative. Using filter materials in locations with a wide range of particulate matter diameters would suffer from filter net clogging problem, resulting in frequent filter material replacement and higher maintenance cost. Filter material with high efficiency and low resistance is of great significance in both human health and energy saving. This paper, taking filter materials used in particulate matter purification as the research object, seeks the design rules and principles for filter materials that give high filter efficiency, low resistance, large dust capacity and long lifespan.First, instruments such as GRIMM Aerosol Speotrometer were used to test the indoor and outdoor actual PMX density and diameter distribution at a college dormitory in Shanghai before and after human activities (cleaning bedding). It was found that the instantaneous value of PM10 density was higher than standard limit and human activities caused an sharp increase in the concentration of TSP. Diameters were in double-peak distribution peaking at 0.20-0.40μm and around 10μm. Therefore, self-purification of residential environment is necessary; meanwhile, taking care of both coarse and fine particulate matters is highly important to human health, energy saving and environment protection.The filtration efficiency for PM10 removal of commonly used pre-filter materials and electrets filter materials were tested, and the influence of particulate matter size, filter velocity, porosity and fiber diameter on the filtration efficiency were determined. The test result indicates that electret filter material has a better performance under various diameter ranges. Considering its use case and repeated usage problem, soaking procedure of electrets filter material in various solutions will largely decrease its efficiency, indicating that electrostatic effects is the reason of its high efficiency and low resistance and it does not apply in situations with rich polar molecules.In order to explore the influence of the structural parameters of air filter media on its resistance, a test rig was built to measure the resistance of selected filter materials. The comparison between experimental and theoretical results demonstrates that an amendment is required for the non-uniform distribution of fiber. In the meantime, based on the experimental results, resistance affection level of filter velocity, porosity, fiber fineness and thickness was analyzed. Relationship formulas between structural parameters and resistance were concluded and the value range weight of each parameter can be used to guide resistance reduction of cleaning materials.Based on the layout of pre-filter material and main filter material and the folding layout of two-layered composite material in air filters, resistance distribution and flow velocity field of filter layer cross-section under different porosities were compared by a value simulation method. The calculation of velocity field unevenness shows that it is related to resistance; compound materials have the characteristics of low resistance and even dust disposition that solve the material clogging problem.By adjusting the fabric layered structure and the filter layer structure of the filter material and replacing current dust in the surface layer with inner layered and scaled dust, excessive resistance increase caused by dust cake in material surface and device space problem due to series connection of pre-filter and main-filter are solved. From the performance study of material compounded from the outer-layer material with large capacity and low resistance and inner-layer electret material with high efficiency, it can be seen that the compound material provides high efficiency against fine particulate matters and keeps the resistance increase within 10%.更多还原