Abstract

Interaction between relative humidity (RH) and hygroscopic particles significantly affects the filtration performance of electret media. To investigate the interaction effect between RH and hygroscopic particles on the loading characteristics, electret media were loaded with potassium chloride (KCl) at ∼30% and ∼75% RH, respectively. Then, to study the effect of RH change on the filtration performance, media loaded at low RH were exposed to air with higher RH. Results showed that electret media loaded at 75% RH experienced a continuous efficiency degradation from 74 to 38%, and the pressure drop only increased by 1 Pa. Because the collected particles deposited on fibers as isolated particles, instead of the dendrites occurred at low RH. After exposing loaded samples to air with RH higher than the loading RH, the efficiency and pressure drop decreased significantly: the efficiency and pressure drop decreased from 74 to 44% and from 37 to 16 Pa within 3 min, respectively, when samples preloaded at ∼30% RH were treated with ∼75% RH. Due to the water adsorption at higher RH, the dendritic structures formed by the collected particles on fibers were damaged, affecting the filtration performance. This work will offer important guidance for practical applications of electret filters.

摘要

相对湿度 (RH) 和吸湿性颗粒之间的相互作用会显着影响驻极体介质的过滤性能。为了研究 RH 和吸湿颗粒之间的相互作用对加载特性的影响，驻极体介质分别加载了约 30% 和 75% RH 的氯化钾 (KCl)。然后，为了研究 RH 变化对过滤性能的影响，以低 RH 负载的介质暴露于具有较高 RH 的空气中。结果表明，在 75% RH 加载的驻极体介质经历了从 74% 到 38% 的持续效率下降，并且压降仅增加了 1 Pa。因为收集的颗粒作为孤立的颗粒沉积在纤维上，而不是在低 RH 时出现枝晶. 将加载的样品暴露在 RH 高于加载 RH 的空气中后，效率和压降显着降低：当在~30% RH 下预加载的样品用~75% RH 处理时，效率和压降分别在 3 分钟内从 74 Pa 降低到 44% 和从 37 Pa 降低到 16 Pa。由于在较高的相对湿度下吸水，纤维上收集的颗粒形成的树枝状结构被破坏，影响过滤性能。这项工作将为驻极体滤波器的实际应用提供重要指导。