Aerosol filtration with slip flow

Chmielewski, R.; Goren, Simon L.

doi:10.1021/es60072a003

Cited by 5 publications

(2 citation statements)

References 10 publications

(22 reference statements)

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“…Using Kuwabara's flow field and Spielman and Goren's flow field, respectively, Pich (1966) and Chmielewski & Goren (1972) have extended the analysis of diffusion and interception and their simultaneous occurrence to incorporate gas mean-free path effects through a slip boundary condition at the collector surface. Their results therefore include the dependence on Knudsen number in addition to those discussed above.…”

Section: Simultaneous Diffusion and Interceptionmentioning

confidence: 99%

Particle Capture from Low-Speed Laminar Flows

Spielman¹

1977

Annu. Rev. Fluid Mech.

197

107

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Section: Simultaneous Diffusion and Interceptionmentioning

confidence: 99%

Particle Capture from Low-Speed Laminar Flows

Spielman¹

1977

Annu. Rev. Fluid Mech.

197

107

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“…The interest for studying slightly compressible gas slip-flow in channels of characteristic dimension comparable to the gas mean free path at the pressure and temperature under consideration is tremendous for many applications that encompass gas flow in microchannels and nanofluidic systems (Porodnov et al 1974;Harley et al 1995;Karniadakis et al 2005;Cai et al 2007), characterization of low permeable porous materials (Lasseux et al 2011;Profice et al 2012) involved in processes ranging from gas production (Darabi et al 2012), gas or nuclear waste storage, filtration and separation (Chmielewski & Goren 1972), composite manufacturing (Zhang et al 2009), among many others. Consequently, a great deal of interest may also be focused on the prediction and estimation of the coefficients governing the physics of gas transport at the macroscale.…”

Section: Introductionmentioning

confidence: 99%

An improved macroscale model for gas slip flow in porous media

2016

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We report on a refined macroscopic model for slightly compressible gas slip flow in porous media developed by upscaling the pore-scale boundary value problem. The macroscopic model is validated by comparisons with an analytic solution on a two-dimensional (2-D) ordered model structure and with direct numerical simulations on random microscale structures. The symmetry properties of the apparent slip-corrected permeability tensor in the macroscale momentum equation are analysed. Slip correction at the macroscopic scale is more accurately described if an expansion in the Knudsen number, beyond the first order considered so far, is employed at the closure level. Corrective terms beyond the first order are a signature of the curvature of solid–fluid interfaces at the pore scale that is incompletely captured by the classical first-order correction at the macroscale. With this expansion, the apparent slip-corrected permeability is shown to be the sum of the classical intrinsic permeability tensor and tensorial slip corrections at the successive orders of the Knudsen number. All the tensorial effective coefficients can be determined from intrinsic and coupled but easy-to-solve closure problems. It is further shown that the complete form of the slip boundary condition at the microscale must be considered and an important general feature of this slip condition at the different orders in the Knudsen number is highlighted. It justifies the importance of slip-flow correction terms beyond the first order in the Knudsen number in the macroscopic model and sheds more light on the physics of slip flow in the general case, especially for large porosity values. Nevertheless, this new nonlinear dependence of the apparent permeability with the Knudsen number should be further verified experimentally.

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

Pan,

Ou,

Romay

et al. 2024

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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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Aerosol filtration with slip flow

Cited by 5 publications

References 10 publications

Particle Capture from Low-Speed Laminar Flows

Particle Capture from Low-Speed Laminar Flows

An improved macroscale model for gas slip flow in porous media

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

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