Surface Structure Enhanced Microchannels for Two-Phase Thermal Management
Abstract
Abstract We propose a fundamental investigation of the role of surface structures on the performance of high flux flow boiling microchannel thermal management devices. Thermal management is a critical bottleneck for advanced electronics, and energy storage and generation devices in electric warships for the U.S. Navy. Two-phase microchannels promise an efficient and high performance approach to dissipate the heat generated via the latent heat of vaporization. Despite the potential of using flow boiling in microchannels to meet the thermal management demands, important operational issues including flow and temperature instabilities limit the state-of-the-art (SoA) systems. The recent use of surface structuring in microchannel devices has demonstrated enhancements in device performance such has increased maximum heat flux dissipation capabilities and reduced flow instabilities. However, past work has focused on water, which is often incompatible with electronic devices. Additionally, understanding the role of the structures on improving flow boiling heat transfer is currently limited. Improved insights are essential to help design optimized devices tailored to the numerous thermal management requirements of the U.S. Navy. We propose a new two-phase microchannel configuration where well-defined micro/nanostructures are fabricated on the bottom heated surface of the microchannel and the other walls of the microchannel have a tailored roughness. This device design is specifically aimed to decouple bubble nucleation for enhanced heat transfer performance and stable device operation. Nucleation occurs via the tailored surface roughness of the microchannel side walls and temperature and flow stability are facilitated by capillary wicking and thin-film evaporation from the bottom heated structured surface. The capillary-assisted-liquid-transport through the surface structures helps sustain a thin liquid film on the heated wall to delay dryout and prevent the accompanying large temperature oscillations. While our initial studies with this proposed device architecture are promising, the results also indicate that more detailed insights are needed to fundamentally probe the role of mirco/nanostructures in two-phase microchannels. The proposed research is aimed to understand how to optimize the micro/nanostructures for boiling enhancement, and realize the fundamental limit of these microchannel devices. Furthermore, we will investigate dielectric fluids, which are critical for implementation in naval applications. In our proposed research effort, we seek to: 1) Fabricate microchannel devices that incorporate a range of well-controlled micro/nanostructures. 2) Characterize heat transfer of the micro/nanostructures in microchannels during flow boiling with dielectric fluids. 3) Optimize the structure geometry and fluid combination for enhanced two-phase thermal management via physics-based model development of the flow boiling process. 4) Develop scalable micro/nanostructure fabrication techniques to facilitate microchannel device integration into operational systems. The insights gained from this research will advance the fundamental understanding of the effects of surface structuring on the performance of flow boiling devices and provide design guidelines for stable, high heat flux thermal management solutions.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 22, 2016
- Source ID
- N000141512483
Entities
People
- Evelyn Wang
Organizations
- Massachusetts Institute of Technology
- Office of Naval Research
- United States Navy