DEVELOPMENT OF ECONOMICAL AIR FILTERS WITH HIGH COLLECTION PERFORMANCE.

随着高科技行业对高净化空间的需求日益增加，超低渗透空气过滤器(ULPA)已被用于洁净室，取代了传统的高效颗粒空气过滤器(HEPA)。此外，在半导体行业中，目前使用的薄膜过滤器的收集效率远远高于ULPA和HEPA，用于去除加压过程气体中的颗粒物。在这些现状下，对这些空气过滤器的下一步要求是在不牺牲其高收集效率的情况下降低其压降。在本工作中，引入了过滤性能指标，定义为颗粒穿透与压降的对数比率，以同时考虑过滤器的收集效率和压降来评价各种空气过滤器的收集性能。以过滤性能指标为依据，考察了纤维滤料和膜式滤料的过滤结构对PE-…收集率的影响对性能进行了更多的考察。此外，对利用静电收集颗粒物的驻极体过滤器的收集性能进行了评估，以考察其是否可以用作经济高效的空气过滤器。结果发现，纤维空气过滤器的收集性能可以通过减小纤维直径、增加平行于气流方向的纤维比例和减少粘结剂的用量来改善。对于膜过滤器，我们根据其结构将其分为五类，发现纤维状结构的膜过滤器比孔状结构的膜过滤器具有更高的收集性能。在此基础上，利用新提出的基于内流收集模型的膜过滤模型，对填料密度较高的膜式过滤器的收集效率进行了预测。针对驻极体滤光片的收尘性能，提出了计算初始收集器效率的理论模型，实验表明，在潮湿空气中，电子纤维上的驻极体电荷是稳定的，固体和大气颗粒物的收集率不随粉尘负荷的增加而降低。然而，当驻极体过滤器用于有机雾颗粒时，电荷在很短的时间内被中和，导致收集效率显著下降。较少

With increasing demand for highly-purified space in high-tech industry, ULPA (Ultra low Penetration Air) filters have been used in clean rooms in place of the conventional HEPA (High Efficiency Particulate Air) filters. Further, in semiconductor industry, membrane filters which have collection efficiency much higher than the ULPA and HEPA are currently used to eliminate particulate matter from pressurized process gases.Under these present situations, the next requirement for these air filters is to reduce their pressure drop without sacrificing their high collection efficiency.In the present work, an index for filter performance, defined as the ratio of logarithm of particle penetration to pressure drop was introduced to evaluate collection performance of various air filters by taking account of both the filter collection efficiency and the pressure drop. On the basis of the filter performance index, the influence of filter structure of fibrous and membrane filters on the collection pe … More rformance was investigated. Furthermore, the collection performance of electret filter which utilizes electrostatic Charge to collect particles was evaluated in order to examine whether it can be used as an economical high collection performance air filter.As a result, it was found that the collection performance of fibrous air filter can be improved (1) by reducing the fiber diameter, (2) by increasing the fraction of fibers which lie parallel to airflow direction, and (3) by reducing the amount of binder. Concerning the membrane filters, we classified them into five groups according to their structure, and found that the membrane filters with fiber-like structure have a higher collection performance than those with pore-like structure. Further, the collection efficiency of membrane filters with a relatively high-packing density was predicted by a newly proposed model based on internal flow collection model. Concerning the collection performance of electret filters, we presented a theoretical model to calculate initial collection efficiency, and experimentally showed that the electret charge on the elect fiber is stable in humid air and that the collection efficiency for solid and atmospheric particles do not decrease with dust load. However, when the electret filter was used for organic mist particles, the charge was neutralized in a short time, leading to a significant decrease in the collection efficiency. Less