SLIDING BUBBLE MOTION AND HEAT TRANSFER FROM A SUBMERGED HEATED PLATE

摘要

It is known that the presence of a moving bubble within a fluid can greatly enhance heat transfer from adjacent heated surfaces. This phenomenon can be observed in common engineering applications such as chemical reactors, shell and tube heat exchangers and in micro-channels. With recent requirements for computer chip cooling, the move to using liquid with phase change is becoming an increasingly attractive alternative to conventional air cooling systems. Thus, it is essential to fully understand this phenomenon in order to accurately predict and control heat transfer rates from electronic devices whose integrity is strongly temperature dependent. Vapour bubbles nucleate, detach, and in some cases impact and slide along downward facing heated surfaces. When this occurs three main factors are found to influence heat transfer: phase change of the fluid, the wake generated behind the bubble and the bubble acting as a bluff body, displacing fluid as it moves. The overall aim of this research is to further advance the current understanding of complex interactions between a single sliding bubble and heat transfer from a flat surface. Results are presented of enhancement to natural convection synchronised with bubble motion together with a more in-depth study of sliding bubble dynamics.