Supercapillary Architecture‐Activated Two‐Phase Boundary Layer Structures for Highly Stable and Efficient Flow Boiling Heat Transfer

Abstract

Development of smaller, faster, and more powerful electronic devices requires effective cooling strategies to efficiently remove ever-greater heat. Phase-change heat transfer such as boiling and evaporation has been widely exploited in various water-energy industries owing to its efficient heat transfer mode. Despite extensive progresses, it remains challenging to achieve the physical limit of flow boiling due to highly transitional and chaotic nature of multiphase flows as well as unfavorable boundary layer structures. Herein, we report a new strategy that promises to approach the physical limit of flow boiling heat transfer. The flow boiling device with multiple channels is characterized with the design of micro-pinfin fences, which fundamentally transforms the boundary layer structures This article is protected by copyright. All rights reserved. 2/22 and impart significantly higher heat transfer coefficient even at high heat flux conditions, in which boiling heat transfer is usually deteriorated due to the development of dryout starting from outlet regions and severe two-phase flow instabilities. Moreover, the approaching of physical limit is achieved without elevating pressure drop.

Enhanced Flow Boiling in Microchannels Integrated with Hierarchical Structures of Micro-Pinfin Fences and Nanowires

“…In this experimental study, flow boiling in three types of microchannel configurations (i.e., conventional plain-wall, pinfin structure only, and SiNW-coated pinfin structure) was investigated and compared. To explore the mechanisms of flow boiling enhancement through SiNWs, flow boiling data in textured μ-pinfin microchannels 19 and SiNW-decorated microchannels 7 with nearly identical channel dimensions were collected and compared. The μpinfin microchannels without the SiNW growth in this study were also used to collect the data of pressure drops with varied working conditions for comparisons.…”

“…7 A micro-pinfin fence (μ-pinfin) along the side wall has also been proposed recently to achieve a stable annular flow. 19 However, the high ratio of the μ-pinfin diameter to the microchannel width results in the increase of the flow resistance and degradation of the efficiency of two-phase flow boiling. There exists a V-shape boiling curve during the early stages of boiling, which represents a less efficient nucleate boiling.…”

“…Silicon NWs (SiNWs) on the side walls have been explored to partially sustain the annular flow with a reduced pressure drop . A micro-pinfin fence (μ-pinfin) along the side wall has also been proposed recently to achieve a stable annular flow . However, the high ratio of the μ-pinfin diameter to the microchannel width results in the increase of the flow resistance and degradation of the efficiency of two-phase flow boiling.…”

Superior Antidegeneration Hierarchical Nanoengineered Wicking Surfaces for Boiling Enhancement

“…[ 21,31–36 ] To date, various observations have illustrated that the surface wickability improves liquid–vapor two‐phase separation during boiling, thereby inhibiting the expansion of the dry area caused by the imbalance between liquid evaporation and replenishment and enhancing critical heat flux (CHF). [ 36–41 ] However, although a variety of structured surfaces having superior wicking have been designed, manufactured, and demonstrated, [ 21,32,35,42,43 ] little to no emphasis has been placed on the degeneration and failure mechanisms of these intrinsically wicking surfaces.…”

Electrostatic tweezer for droplet manipulation

“…These tweezers have been widely used to manipulate many kinds of micro-/nanometal particles, bioparticles, liquid droplets, and so on. In particular, well-controlled liquid droplet manipulation is essential to various practical fields ( 4 – 7 ), such as printing technology ( 8 ), heat management ( 9 – 11 ), water harvesting ( 12 , 13 ), biological assays ( 14 ), chemical reactions ( 15 , 16 ), and frost prevention ( 17 , 18 ). Despite remarkable significances, the droplet manipulation using these physical tweezers has achieved less progress, probably owing to the fluidic nature of droplets, which are soft and deformable in diverse operating conditions and mediums.…”