Controlled generation of a vapor bubble representative of nucleate boiling conditions using transient focused laser heating

Abstract

Nucleate boiling is a phenomenon of significant importance in a broad range of industries. Increasing boiling performance parameters could lead to more efficient power plants and better electronics thermal management. However, difficulties associated with studying this extremely complex phenomenon have prevented a meaningful progress in the area of boiling heat transfer enhancement. In this paper, we implement a laser-based controlled bubble generation technique to enable accurate phenomenological studies of the boiling process. We present details of the transient focused-laser heating mechanism used to nucleate a microscale vapor embryo on the boiling surface. We present high-speed optical imaging data showing how this vapor embryo grows into a bubble using electrically applied background heat flux. Unlike the currently available artificial bubble generation approaches, which either generate unphysical bubbles or are extremely difficult to implement, we show that the laser-nucleated controlled single bubble demonstrates bubble ebullition characteristics closely representative of naturally occurring bubbles in nucleate pool boiling.