Adhesion force analysis for prevention of particle resuspension in multiplexed inertial coalescence filters

Abstract

Fine airborne particles (<10 µm) pose challenges for engineered systems, human health, and environmental pollution. This work investigates the relative influences of van der Waals and capillary adhesion forces during filtration to guide the design of multiplexed inertial coalescence filters, which are constructed with a parallel series of helical passageways designed for low pressure drop (<150 Pa) and capture of fine particulate matter (5–50 μm). Specifically, we experimentally quantified the influence of particle adhesion forces on filtration efficiency for capture of 6.1 µm activated carbon particle clusters. Filtration efficiency for dry filters, where van der Waals adhesion forces dominate, is significantly diminished beyond a threshold flowrate due to the Saffman lift force, which causes wall-bound particle clusters to detach from the interior filter surfaces. For wetted filters, the capillary adhesion force is orders of magnitude greater than the Saffman lift force, and consequently the filtration efficiency is not adversely affected. We developed models for filter pressure drop and filtration efficiency accounting for the influence of particle adhesion forces; these models showed good agreement with experimental results. Filter quality factor (QF) was determined for varying particle sizes and flowrates and can be used as a design guideline for use-case-specific filter optimization, which is enabled by the customizable additive manufacturing approach used to fabricate the filters. Due to its versatility and low-pressure-drop nature, this filtration approach could find use in heating, ventilation, and air conditioning (HVAC), large particle and dust filtration in industrial processes, cleanroom pre-filtration, and beyond.

Copyright © 2024 American Association for Aerosol Research

EDITOR:

• Se-Jin Yook

Acknowledgments

We acknowledge helpful discussions with Dr. John C. Graf of the US National Aeronautics and Space Administration (NASA) Johnson Space Center.

Disclosure statement

The authors declare the following financial interests which may be considered as potential competing interests: R.M.R and D.J.P have ownership stakes in the company Helix Earth Technologies Inc., a Delaware C corporation that is commercializing the technology detailed in this work and also pursuing intellectual property on the technology developed in this work.

Data availability statement

The data that support the findings of this study are available within the article and its Supplementary Material, which details development of the mathematical models, experimental methods, and droplet deployment methods.

Additional information

Funding

Funding support for this project was provided by Jacobs Engineering Group Inc. on behalf of NASA. R.M.R. is grateful for support from the U.S. Department of Energy (DOE) Innovation in Buildings (IBUILD) fellowship. This research was supported in part by an appointment with the Energy Efficiency & Renewable Energy (EERE) Science, Technology and Policy Program sponsored by the U.S. Department of Energy (DOE). This program is administered by the Oak Ridge Institute for Science and Education (ORISE) for the DOE. ORISE is managed by ORAU under DOE contract number DE-SC0014664. All opinions expressed in this article are the author’s and do not necessarily reflect the policies and views of DOE, ORAU, or ORISE. A.R. acknowledges support from the Rice University Academy of Fellows. This work was supported by the Smalley Curl Institute Student Training for Advising Research (SCI-STAR) grant. This work was conducted in part using resources provided by the Shared Equipment Authority at Rice University. This work was supported by a Research Experience for Undergraduates (REU) program hosted by the Nanosystems Engineering Research Center for Nanotechnology Enabled Water Treatment (NEWT), funded by the National Science Foundation under Grant No. EEC-1449500.