Article ID: 11we214
Ultrasonic atomization, a process of generating fine droplets through irradiation of high-frequency ultrasound to a gas-liquid interface from the liquid underneath, is applied to separating ethanol from its aqueous solution. Towards its practical use, the process of collecting in two cooling stages the ethanol-enriched mist-generated via an ultrasonic atomizer (ultrasonic transducer operated at 2.4 MHz) with continuous feed of ethanol-water solution-using two cooling units in a series has been developed. The effects of operating conditions, especially cooling temperatures and gas flowrate, on ethanolenrichment and condensation characteristics are examined. It is found that the highly-enriched ethanol recovery could be attained in the 2nd stage by optimizing the 1st- and 2nd-stage cooling temperatures (as moderate as 5°C and up to-10°C, respectively). Regarding the carrier-gas flowrate, ethanol-rich mist consisting of small-size droplets tends to be carried selectively in favor of lower gas flowrate. Nevertheless, the desired recovery of enriched ethanol-i.e., a highest possible value of the recovered quantity of ethanol as well as the recovery concentration itself-is expected to be obtained in the 2nd stage by raising the carrier-gas flowrate under the present operating conditions. While the proposed two-stage cooling process tends to collect rather an appreciable quantity of less-enriched ethanol solution in the 1st stage, it is the 2nd stage that assures the desired quality of enriched-ethanol recovery.