Particle Collection of Electret Media under Different Filtration Pressures

Liu, Zhen; Chen, Da‐Ren; Cao, Liwen; Mensah, Desmond Asiedu; Ji, Zhongli

doi:10.4209/aaqr.220405

Cited by 2 publications

(1 citation statement)

References 30 publications

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“…The theoretical single fiber efficiency model was developed to predict the FE of both charged (or electret) and uncharged (or mechanical) filter media under clean conditions (Chang et al, 2016;Hinds, 1999). It is widely applied, and here we summarize the models that can accurately predict the FEs for researchers' reference (Chang et al, 2016(Chang et al, , 2018Liu et al, 2023;Tien et al, 2020). The theoretical particle penetration, P theo , is calculated as (Bahk et al, 2013;Hinds, 1999;Wang et al, 2007Wang et al, , 2011:…”

Section: Theoretical Filtration Efficiencymentioning

confidence: 99%

An Empirical Equation for Rapid Validation of the Performance of Commercial N95 Equivalent Respirators

Chen,

Zhang,

Jing

et al. 2024

KONA

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The COVID-19 pandemic has underscored the importance of wearing effective facepiece filtering respirators (FFRs) to reduce infection and disease transmission. One of the reasons causing the widespread prevalence was found to be the failure of N95-Equivalent FFRs (N95-EFs), i.e., efficiency <<95 %, during the pandemic. To investigate the reasons causing the ineffectiveness of commercial N95-EFs, this study measured the efficiency of several dozens of commercially available N95-EFs following standard testing protocols. The specifications of the N95-EF including fiber diameter, solidity and surface potential of the main layer media of N95-EFs were also determined. We provide a simple method for manufacturers to quickly screen the efficiencies of their N95-EF products before distributing them to the market. We found that the failures of N95-EF are majorly attributed to overprediction of the efficiency due to i) missing neutralization of challenging particles, ii) too small or oversize of challenging particles, and iii) particle detectors with large sizing limits (>500 nm). Based on the pressure drop, respirator area, and surface potential of the N95-EFs, an empirical equation is developed to fast screen and help design effective N95-EFs.

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Section: Theoretical Filtration Efficiencymentioning

confidence: 99%

An Empirical Equation for Rapid Validation of the Performance of Commercial N95 Equivalent Respirators

Chen,

Zhang,

Jing

et al. 2024

KONA

Self Cite

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Experimental and Numerical Investigation of Slip Effect on Nanofiber Filter Performance at Low Pressures

Pan,

Ou,

Romay

et al. 2024

Small

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Nanofiber filters are widely used in air filtration applications due to their superior performance over microfiber filters. Velocity slip around nanofibers has been identified as a key factor contributing to their high figure of merit, yet its impact on filter performance, especially particle collection efficiency, remains unclear due to the difficulty in isolating the slip effect as the sole variable. This study combines experimental and simulation methods to investigate the slip effect by adjusting the air molecule mean free path, rather than varying fiber size as done in previous studies. Filter media with mean fiber sizes ranging from 16.2 to 0.084 µm are utilized. An image‐based regression method is developed to address the challenge of determining the solidity of thin nanofiber layers. The results show that the slip effect is enhanced as the testing pressure decreases, reducing pressure drop by less than 15% for microfiber filters and over 50% for nanofiber filters ≈100 nm. The enhanced slip effect at low pressures (i.e., relatively low pressure compared to the ambient environment) significantly improves filtration efficiency, especially for particles larger than 100 nm. It also proposes semi‐empirical equations for predicting filter performance in slip and transition flow regimes.

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Particle Collection of Electret Media under Different Filtration Pressures

Abstract: In honor of Prof. David Y.H. Pui for his "50 Years of Contribution in Aerosol Science and Technology" (I)

Cited by 2 publications

References 30 publications

An Empirical Equation for Rapid Validation of the Performance of Commercial N95 Equivalent Respirators

An Empirical Equation for Rapid Validation of the Performance of Commercial N95 Equivalent Respirators

Experimental and Numerical Investigation of Slip Effect on Nanofiber Filter Performance at Low Pressures

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