A fundamental study of transient processes in microscale flow boiling heat transfer

Abstract

In this work, experimental methods, data processing technique, and results along this vein are presented. With a new microdevice architecture, synchronized temperature and high-speed camera footage several interactions encountered in flow boiling are examined.

Using a computational workflow to decouple the conjugated conduction-convection effects and account for the transient heat loss (or gain), the local and transient heat transfer coefficient was measured for different flow regimes. Using a non-dimensional number to describe the extent of damping exerted by the substrate, detailed considerations of sensor design for transient studies are presented. Based on these fundamental heat transfer considerations spatiotemporal bounds are identified that allow for a continuous estimate of the transient heat transfer coefficient. These estimates of the spatiotemporally resolved heat transfer coefficient are compared to the time averaged considerations for the thin-film evaporation process accompanying slug flow.

Electronics cooling is at the forefront of the design of the next generation of commercial and military electronics. Several developments in the design of electronics have created the need for an unprecedented level of integration between the electronic and thermal components. Flow boiling in microchannels offers significant advantages over other competing technologies to address the grand scale of challenges involved with the advent of 3-D chip stacks. Practical implementations are limited by the lack of fundamental knowledge controlling the heat transfer processes at confined length scales. Transient local wall temperature and heat transfer coefficient measurements can be used to address several of these gaps in contemporary literature.