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不断增加，ULPA（超低渗透空气）过滤器已在洁净室中取代传统的HEPA（高效颗粒空气）过滤器。此外，在半导体工业中，目前使用捕集效率远高于ULPA和HEPA的薄膜过滤器来消除加压工艺气体中的颗粒物。在这种现状下，对这些空气过滤器的下一个要求是在不牺牲其高捕集效率的情况下降低其压降。在目前的工作中，引入了过滤器性能指标（定义为颗粒穿透对数与压降的比率），通过考虑过滤器捕集效率和压降来评估各种空气过滤器的捕集性能。在过滤器性能指标的基础上，研究了纤维过滤器和膜过滤器的过滤结构对收集性能的影响。此外，还对利用静电荷收集颗粒的驻极体过滤器的收集性能进行了评估，以检验其是否可以用作经济的高收集性能空气过滤器。结果发现，纤维空气过滤器的收集性能可以通过（1）减小纤维直径，（2）通过增加平行于气流方向的纤维比例，以及（3）减少粘合剂的量来提高。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。此外，通过新提出的基于内流收集模型的模型预测了具有相对高填充密度的膜过滤器的收集效率。针对驻极体过滤器的捕集性能，我们提出了计算初始捕集效率的理论模型，并通过实验表明，驻极体纤维上的驻极体电荷在潮湿空气中稳定，并且对固体和大气颗粒物的捕集效率不会随着含尘量的增加而降低。然而，当驻极体过滤器用于有机雾粒时，电荷会在短时间内被中和，导致捕集效率显着下降。较少的

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