环境相对湿度对颗粒物过滤性能的影响

Effect of ambient relative humidity on particle filtration performance

以吸湿性氯化钠(NaCl)颗粒和非吸湿性氧化铝(Al_(2)O_(3))颗粒为实验对象,使用纤维材料过滤介质,引入纳米和微米两类颗粒物尺度,考察不同相对湿度(RH)环境下颗粒物过滤性能的变化规律及内在机理。结果表明:低湿度下(RH20%和50%)过滤吸湿性颗粒时,压降呈线性增长趋势,高湿度下(≥RH80%)会出现压降的急剧升高;非吸湿性颗粒受湿度变化的影响较小,但在饱和湿度下(RH100%)压降增长较为显著;滤料初始过滤效率对环境中相对湿度的变化不敏感,也不会受到颗粒吸湿性能差别的影响;在颗粒加载过程中,受滤料纤维表面颗粒物沉积的影响,过滤效率持续缓慢增长,但湿度超过颗粒潮解点后,对吸湿性颗粒的过滤效率出现一定程度下降,类似液体过滤机制;此外,环境湿度的变化对于纳米颗粒物过滤性能的影响远比微米颗粒更为显著。研究结果可为空气污染防治中颗粒物过滤技术的应用与改进提供参考。

This article investigated the variation pattern and intrinsic mechanism of particle filtration performance with different ambient relative humidity(RH).Hygroscopic sodium chloride(NaCl)particles and non-hygroscopic alumina(Al_(2)O_(3))particles were used as experimental objects.Two types of particulate matter scales,nano and micron,were introduced in the experiments and fibrous materials were selected as filtration media.The results indicated that the pressure drop increased linearly in filtering hygroscopic particles at low humidity(RH20%and 50%),and a sharp elevation in pressure drop occurred at high humidity(≥RH80%).Non-hygroscopic particles were less affected by variations of humidity,but the growth in pressure drop was more significant at saturation humidity(RH100%).The initial filtration efficiency of the filter media was insensitive to variations in ambient relative humidity and was hardly affected by differences in the hygroscopic properties of the particles.During particle loading,the filtration efficiency continued to increase slowly due to the influence of particle deposition on the surface of the filter media fiber,but when the humidity exceeded the paticle delixing point,the filtration efficiency of hygroscopic particles decresed to a certain extent,similar to the liquid filtration mechanism.In addition,variations in ambient humidity had a more significant effect on the filtration performance of nanoparticles than microparticles.The results of this research could provide guidance for the application and improvement of particulate matter filtration technology in air pollution control.