A high-power ultrasonic microreactor and its application in gas–liquid mass transfer intensification

Abstract

The combination of ultrasound and microreactor is an emerging and promising area, but the report of designing high-power ultrasonic microreactor (USMR) is still limited. This work presents a robust, high-power and highly efficient USMR by directly coupling a microreactor plate with a Langevin-type transducer. The USMR is designed as a longitudinal half wavelength resonator, for which the antinode plane of the highest sound intensity is located at the microreactor. According to one dimension design theory, numerical simulation and impedance analysis, a USMR with a maximum power of 100 W and a resonance frequency of 20 kHz was built. The strong and uniform sound field in the USMR was then applied to intensify gas-liquid mass transfer of slug flow in a microfluidic channel. Non-inertial cavitation with multiple surface wave oscillation was excited on the slug bubbles, enhancing the overall mass transfer coefficient by 3.3-5.7 times.

Liquid–liquid two‐phase flow in ultrasonic microreactors: Cavitation, emulsification, and mass transfer enhancement

“…The detailed description of the design, fabrication, and characterization of the USMR have been involved in our previous paper . The whole USMR is designed as a longitudinal half wavelength resonator with antinode plane of the highest sound intensity located at the microreactor plate .…”

“…The detailed description of the design, fabrication, and characterization of the USMR have been involved in our previous paper . The whole USMR is designed as a longitudinal half wavelength resonator with antinode plane of the highest sound intensity located at the microreactor plate . As shown in Figure a, the microreactor plate (LY12 aluminum alloy, 3 mm in thickness) was directly coupled with a Langevin‐type ultrasonic transducer (ZFHN‐100‐21.5, Baoding Zhengjie Electric, China) by an ultrasonic transmission gel (THD‐383, Taiheda, China).…”

“…The mechanical effect of ultrasonic irradiation can enhance mixing as well as avoid the clogging problem in microreactors . In the meanwhile, strong and uniform ultrasonic field can be realized in microreactors due to their much smaller volume in comparison with conventional reactors …”

“…In our previous work, a highly efficient ultrasonic microreactor has been built and applied to enhance miscible liquid mixing and gas–liquid mass transfer processes . Following these research, we extend the application of this reactor to immiscible liquid–liquid system.…”

Novel energy harvesting using acoustically oscillating microbubbles

“…It also generates an attraction/repulsion force (i.e., radiation force or Bjerknes force) depending on the size and density of the medium and object [7,8]. Based on these secondary effects, various microfluidic components (e.g., micropumps [9][10][11][12], manipulators [13,14], micromixer [15][16][17], micromotor [18]) and biological applications (e.g., drug delivery [19] and cell lysis [20,21]) have been developed. More detailed information on practical applications is available in review papers [4,19,22].…”