Optimization of boiling heat transfer by visualization and boiling sound in a boiling bubble resonator

Abstract The boiling bubble resonator (BBR) is a heat transfer enhancement technique that uses boiling bubbles. Boiling heat transfer enhancement by a BBR is passive, using the pressure of boiling bubbles without consuming electricity. In this study, we directly evaluated the relationship between the process of supplying a subcooled liquid and the vibration of the BBR plate using an image processing technique for particle image velocimetry (PIV). This approach enabled us to observe the resonator's periodic vibration of the BBR plate resulting from the flow phenomena of boiling bubbles generated from a vibrating plate during the boiling heat transfer process. In addition, we simultaneously acquired the boiling sound and checked the correlation of three states. We found the vibration length in the case where the boiling heat transfer phenomenon was promoted to its maximum. We also investigated resonance phenomena in an SUS304 plate and brass plates with similar resonance frequencies. The results showed that a resonance phenomenon occurred in the brass when the plate length matched the period of boiling bubbles, and boiling heat transfer was enhanced. However, the resonance phenomenon did not occur in the SUS304, and the boiling heat transfer was not promoted because of poor wetting characteristics where the subcooled liquid was supplied.