Measurement of acoustically induced mass transfer in wet-wall narrow channels

Acoustically induced mass transfer was investigated experimentally using a standing-wave thermoacoustic cooler. The cooler comprised three ceramic honeycombs with narrow channels, an acoustic driver, and a tube. The three honeycombs were placed in series within the tube. The central honeycomb was wet, and the others were dry. One end of the tube was closed with a rigid plate, while the other end was connected to the acoustic driver. When an acoustic wave was introduced via the driver, a temperature gradient developed along the honeycombs due to thermoacoustic effects. The weights of the three honeycombs were measured before and after the acoustic wave was applied. This experiment allowed determination of both the amount and direction of the mass transfer. The results revealed two key findings. First, the value of the mass transfer reached a maximum of 0.39 mg/s. Second, the direction of the mass transfer depended on the temperature gradient along the honeycombs: When the temperature gradient was small, the mass was transferred from the speaker side toward the closed end; when the temperature gradient was large, the direction was reversed. These results were compared with numerical predictions, and the comparison showed good quantitative agreement.