Raynor P C, Kim B G, Ramachandran G, Strommen M R, Horns J H, Streifel A J
Division of Environmental Health Sciences, University of Minnesota, Minneapolis, MN 55455, USA.
Indoor Air. 2008 Feb;18(1):51-62. doi: 10.1111/j.1600-0668.2007.00504.x. Epub 2007 Dec 18.
Synthetic filters made from fibers carrying electrostatic charges and fiberglass filters that do not carry electrostatic charges are both utilized commonly in heating, ventilating, and air-conditioning (HVAC) systems. The pressure drop and efficiency of a bank of fiberglass filters and a bank of electrostatically charged synthetic filters were measured repeatedly for 13 weeks in operating HVAC systems at a hospital. Additionally, the efficiency with which new and used fiberglass and synthetic filters collected culturable biological particles was measured in a test apparatus. Pressure drop measurements adjusted to equivalent flows indicated that the synthetic filters operated with a pressure drop less than half that of the fiberglass filters throughout the test. When measured using total ambient particles, synthetic filter efficiency decreased during the test period for all particle diameters. For particles 0.7-1.0 mum in diameter, efficiency decreased from 92% to 44%. It is hypothesized that this reduction in collection efficiency may be due to charge shielding. Efficiency did not change significantly for the fiberglass filters during the test period. However, when measured using culturable biological particles in the ambient air, efficiency was essentially the same for new filters and filters used for 13 weeks in the hospital for both the synthetic and fiberglass filters. It is hypothesized that the lack of efficiency reduction for culturable particles may be due to their having higher charge than non-biological particles, allowing them to overcome the effects of charge shielding. The type of particles requiring capture may be an important consideration when comparing the relative performance of electrostatically charged synthetic and fiberglass filters.
Electrostatically charged synthetic filters with high initial efficiency can frequently replace traditional fiberglass filters with lower efficiency in HVAC systems because properly designed synthetic filters offer less resistance to air flow. Although the efficiency of charged synthetic filters at collecting non-biological particles declined substantially with use, the efficiency of these filters at collecting biological particles remained steady. These findings suggest that the merits of electrostatically charged synthetic HVAC filters relative to fiberglass filters may be more pronounced if collection of biological particles is of primary concern.
由带有静电荷的纤维制成的合成过滤器和不带静电荷的玻璃纤维过滤器在供暖、通风和空调（HVAC）系统中都被广泛使用。在一家医院运行的HVAC系统中，对一组玻璃纤维过滤器和一组带静电的合成过滤器的压降和效率进行了为期13周的反复测量。此外，在一个测试装置中测量了新的和使用过的玻璃纤维及合成过滤器收集可培养生物颗粒的效率。调整到等效流量后的压降测量表明，在整个测试过程中，合成过滤器的运行压降不到玻璃纤维过滤器的一半。当使用总环境颗粒进行测量时，合成过滤器在测试期间对所有粒径的效率都有所下降。对于直径为0.7 - 1.0微米的颗粒，效率从92%降至44%。据推测，收集效率的这种降低可能是由于电荷屏蔽。在测试期间，玻璃纤维过滤器的效率没有显著变化。然而，当使用环境空气中的可培养生物颗粒进行测量时，无论是合成过滤器还是玻璃纤维过滤器，新过滤器和在医院使用13周的过滤器的效率基本相同。据推测，可培养颗粒效率没有降低可能是因为它们比非生物颗粒具有更高的电荷，从而使它们能够克服电荷屏蔽的影响。在比较带静电的合成过滤器和玻璃纤维过滤器的相对性能时，需要捕获的颗粒类型可能是一个重要的考虑因素。
具有高初始效率的带静电合成过滤器在HVAC系统中可以经常替代效率较低的传统玻璃纤维过滤器，因为设计合理的合成过滤器对气流的阻力较小。尽管带电荷的合成过滤器在收集非生物颗粒方面的效率随着使用而大幅下降，但这些过滤器在收集生物颗粒方面的效率保持稳定。这些发现表明，如果主要关注生物颗粒的收集，带静电的合成HVAC过滤器相对于玻璃纤维过滤器的优点可能会更加明显。
