Enhancement of mixing by microbubble emission boiling in a microfluidic device

Abstract

The effect of microbubble emission boiling (MEB) on the mixing of two fluids in a microfluidic device was studied experimentally. When MEB occurred on an electric heater made of a platinum wire with a diameter of 30 micrometers, the mixing of the two fluids increased markedly. However, nucleate boiling had no significant effect on the mixing. A high-speed video showed that the very rapid growth and collapse of micro boiling bubbles on the heater causes the strong mixing of the two fluids. The coexistence of highly superheated and highly subcooled water near the heater seems to be the reason for such enhanced mixing.

Experimental investigation of transition process from nucleate boiling to microbubble emission boiling under transient heating modes

“…In MEB, a process of vapor bubble/film being condensed and collapsed repeats rapidly, accompanied by violent motion of microbubbles and loud boiling sound. Therefore, MEB has great potential in meeting the demand of not only cooling high heat release equipment but also the enhancement of mixing fluids …”

A study visualizing the collapse of vapor bubbles in a subcooled pool

“…Inada et al [1] firstly conducted a series of experiments of MEB at 15-85 K subcooling on a copper heating surface to which a thick platinum foil was attached. Then, Shoji et al [2], Tange et al [3], Kato et al [4] and Ueno et al [5] performed experiments of MEB on a thin platinum wire. In studies of [4], MEB phenomenon was used to mix two fluids in a microfluidic device.…”

“…Then, Shoji et al [2], Tange et al [3], Kato et al [4] and Ueno et al [5] performed experiments of MEB on a thin platinum wire. In studies of [4], MEB phenomenon was used to mix two fluids in a microfluidic device. Suzuki et al conducted a large number of experiments under both conditions of subcooled pool and flow boiling to research MEB.…”

Role of step-shape structures and critical failure bubble volume in micro bubble constraint

“…Micro gas bubbles have been used in a variety of new devices for their special advantages since thermal bubbles were successfully used in ink jet printer heads [1]. Micro bubbles have been used to compose micro pumps [2][3][4], micro valves [5,6] and micro mixers [7][8][9][10], promising no moving mass block, simple operation, miniature size, large actuation force and the ability to conform to different micro-channel cross sections [2]. In computer technology, micro bubbles are studied to create micro heat exchangers or cooling systems for electronic devices [11].…”