Influence of Triggered Seed Bubbles on Flow Boiling in Microchannels

Combined with a simple phase change model, the Volume of Fluid (VOF) method is used for simulating the seed bubble triggered boiling in a single circular microchannel with 6.5mm length. Simulation results show that the introduction of seed bubbles improves the heat transfer performance and suppresses the flow instability simultaneously. The seed bubbles are triggered into the microchannel forf=2000 Hz, passing by only about five numbers of periods, the wall superheats remarkably decreased, a complete thermal equilibrium between the liquid and vapor phases is approached, the flow instability can be controlled successfully. At the stable flow stage, the heat transfer which can reach more than 3 times the single liquid phase heat transfer dominated by the local liquid film thickness, which is the actual heat transfer length-scale in the liquid film regime. However, the liquid bridge region existing between the bubbles produces a week heat transfer mechanism.