Abstract
A novel vibration induced droplet atomization (VIDA) technology is utilized in a two-phase heat transfer cell for cooling of high-power integrated circuits. VIDA is a rapid atomization process whereby discrete liquid drops (or liquid film) are placed on the surface of a diaphragm that is vibrated near or at the coupled resonance of the system. Surface waves that develop on the liquid free surface lead to rapid bursting and the ejection of secondary droplets that are propelled away from the diaphragm. The VIDA-based heat transfer cell is similar to a heat pipe in that cooling is based on the evaporation and condensation of liquid within a closed cell. However, in contrast to a heat pipe where the liquid is delivered to the evaporator by capillary transport within a wicking material, in the VIDA cell the atomized liquid droplets are propelled towards the hot surface thus eliminating the capillary transport limit that is imposed by the wicking material. The vapor condenses near an air-side heat exchanger and the condensate is delivered to the VIDA driver. The rate of atomization and therefore the heat transfer within the cell can be actively controlled and regulated. The present paper focuses on the fundamental aspects of the VIDA atomization process of a single liquid drop. It is shown that VIDA process can be either self-intensifying or self-decaying. The global features of the VIDA, spray droplet size- and velocity distributions, and their interrelation with the external driving parameters are investigated. Finally, the performance of a current prototype of VIDA heat transfer cell is discussed.
