Adsorption-Mediated Mass Streaming in a Standing Acoustic Wave

Abstract

Oscillating flows can generate nonzero, time-averaged fluxes despite the velocity averaging zero over an oscillation cycle. Here, we report such a flux, a nonlinear resultant of the interaction between oscillating velocity and concentration fields. Specifically, we study a gas mixture sustaining a standing acoustic wave, where an adsorbent coats the solid boundary in contact with the gas mixture. It is found that the sound wave produces a significant, time-averaged preferential flux of a "reactive" component that undergoes a reversible sorption process. This effect is measured experimentally for an air-water vapor mixture. An approximate model is shown to be in good agreement with the experimental observations, and further reveals the interplay between the sound-wave characteristics and the properties of the gas-solid sorbate-sorbent pair. The preferential flux generated by this mechanism may have potential in separation processes.

PC-TAS: A design environment for phase-change and classical thermoacoustic systems

“…Based on the long-wavelength, low amplitude acoustic approximation, the full equations can be simplified into three ODEs. This simplified model was first developed by Raspet et al [5] and Slaton et al [6], and later extended by Weltsch et al [15] and Offner et al [7] to include other mass-exchange processes (e.g., absorption and adsorption). Here, we use the dimensional versions of the equations derived in Offner et al [7]:…”

Multi-physics coupling in thermoacoustic devices: A review

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Acoustic oscillations driven by boundary mass exchange

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“…where the mass and total power fluxes are second-order streaming effects, and are hence scaled with ε 2 . The mass flux derivation appears in Weltsch et al (2017), and in our scaled form it readṡ…”