RUI: Two-dimensional flow-boiling characteristics under surface wettability gradient

Washington State University, Pullman WA

Investigators

Abstract

As technology becomes increasingly miniaturized, extremely concentrated power consumption from advanced electronic devices leads to the challenge of how to keep devices from overheating. Conventional thermal solutions are inadequate for advanced high power density semiconductor devices for wireless and military applications. Flow-boiling, highly efficient phase-changing thermal energy conversion/transport phenomena, can be incorporated into microgap heat-sink technique as a promising thermal solution for high power density electronics. However, local excessive evaporations (dry-outs) by highly concentrated heat sources and consequent unevenness in flow distribution has been a challenging issue. In this project, microgap surface wetting property will be modified to address this issue; i.e., highly wetting surfaces imposed on hot-spots will enhance liquid-phase entrainment and thus prevent dry-out. The successful accomplishment of this project will advance fundamental knowledge in complex multiphase flow and heat transfer, enable cooling of futuristic electronic devices, and transfer state-of-the-art knowledge and experience to undergraduate and K-12 students. The objective of this project is to attain fundamental knowledge about two-dimensional flow-boiling morphology and heat transfer characteristics under a surface wettability gradient. Despite the critical importance, the understanding of 2-D flow-boiling morphological behavior is very limited. Mere extension of 1-D theories cannot accommodate the 2-D complications and consequences. The proposed research tasks will investigate the 2-D flow-boiling morphology and vapor ebullition cycle, which will explain 2-D energy transport mechanisms related to the flow-boiling. The effect of multiphase forces on the vapor dispersion behaviors will be explored as well. Microgap surfaces with various wetting properties will be fabricated and tested to study how the induced capillary force modify the multiphase force balance and eventually affect 2-D flow-boiling phenomena.