Modeling performance of thin fibrous coatings with orthogonally layered nanofibers for improved aerosol filtration

• Thin orthogonal filter coatings act as a fibrous nano-sieve to capture particles.
• This paper models performance characteristics based on microstructure.
• Such coatings can be added to conventional filters for performance enhancement.
• Performance is independent of coating imperfections for particle–fiber-size pairs.
• Filter performance improves when its mass is distributed across multiple layers.

Advances in nanofiber fabrication techniques (e.g., electrospinning) have come to allow control over fiber distribution and orientation such that an ordered coating with fibers arranged in layers orthogonal to one another can potentially be produced. Such coatings can serve as a nano-sieve that can be designed and placed on the downstream side of a conventional nonwoven fibrous filter to enhance its performance (collection efficiency for a given pressure drop). This paper presents a thorough analysis of the performance characteristics of these thin coatings to guide the fabrication process in terms of the coatings' microstructural properties. In particular, we have found a correlation such that, for coatings composed of a given fiber size, there exists a corresponding particle size for which a coating's performance becomes independent of variations in fiber-to-fiber spacing (i.e., coating's non-homogeneity). We have also found that a coating's performance improves when its mass is distributed across more than one pair of orthogonal layers.

There exists, for each particle size, a fiber diameter (about three times greater) for which the performance of a nanofiber coating with orthogonally oriented layers is not affected by coating's non-homogeneity.Figure optionsDownload as PowerPoint slide