Investigation of the filtration performance of electret media for deliquescent and non-deliquescent aerosols under different relative humidity

Abstract

Electret media have gained widespread interest due to their high efficiency, low resistance and ability to capture sub-micron particles. However, their filtration performance changes significantly with environmental conditions, especially relative humidity, which poses challenges for their broader application. The effect of relative humidity on the filtration performance of electret media was studied in this paper. First, the effects of different environmental factors on the initial filtration efficiency of electret media were explored. Then, dust-holding experiments using aerosols with different deliquescent properties were conducted at four relative humidity levels: 30% RH, 50% RH, 70% RH and 80% RH. Results showed that when KCl aerosol was used as challenging dust under high relative humidity, the filtration efficiency of electret media declined sharply, especially at 80% RH, where it declined by 43.2% without rebounding. The pressure differential was only increased by 1 Pa. However, when Al₂O₃ aerosol was used, the filtration performance remained stable across different relative humidity levels. A new index was introduced to evaluate the comprehensive filtration performance of electret media during the dust-holding process under different relative humidity. The research emphasized the importance of considering relative humidity when using electret media and the need for timely product inspection and replacement.