Application of vortex generators to avoid subcooled flow boiling oscillation in micro-channel

Abstract

Subcooled flow boiling in micro-channels is an effective solution for high-heat-flux electronics thermal management, and the heat flux has a limitation value (i.e., limiting oscillation heat flux) due to flow boiling oscillation. The purpose of this study is to propose a new method to suppress the flow boiling oscillation (i.e., forcing bubbles to leave the channel by installing a vortex generator), experimentally verify the effect of vortex generators on suppression of flow boiling oscillation and increasing limiting oscillation heat flux, and develop a predicting correlation for this heat flux. In the experiments, the vortex generator is a helix wire with a pitch of 1.8 mm, a length of 22.5 mm, a wire diameter of 0.2 mm and a diameter of 1.8 mm; the inlet subcooling degree and mass flux range from 10 – 50 K and 750–1750 kg m−2 s−1, respectively. The results show that, the flow boiling oscillation occurs in the flow channel without vortex generators while it doesn't occur in the flow channel containing vortex generators at the same working condition; the vortex generators can raise the limiting oscillation heat flux with a maximum increment of 21.1%, which indicates that vortex generators can suppress the flow boiling oscillation. A new correlation predicting limiting oscillation heat flux in channels with vortex generators was developed, and its predictions match 95% of the experimental data within ± 20% while the average deviation is 7.6%.