Capillary-driven liquid film boiling heat transfer on hybrid mesh wicking structures

• Published in: Nano energy Vol. 51; pp. 373 - 382
• Main Authors: Wen, Rongfu, Xu, Shanshan, Lee, Yung-Cheng, Yang, Ronggui
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2018
• Subjects: Capillary evaporation; Copper woven mesh; Heat transfer enhancement; Hybrid wicking; Liquid film boiling; Thermal management; Heat transfer enhancement; Liquid film boiling; Thermal management; Hybrid wicking; Capillary evaporation; Copper woven mesh
• ISSN: 2211-2855
• DOI: 10.1016/j.nanoen.2018.06.063

Thermal management of high power electronic systems such as advanced lasers, light emitting diodes, radars, microprocessors, electrical machines, and power inverters, is becoming critical in defense, space, and commercial applications. As a liquid-vapor phase-change process, capillary evaporation on wicking structures has received increased interest owing to its capability dissipating high heat flux by increasing the effective evaporation area and sustaining the liquid supply. However, the approaches based on capillary evaporation suffer from intrinsic tradeoffs between the low thermal resistance for heat flow and the high wicking flow rate for liquid supply, which make it challenging to optimize both heat transfer coefficient (HTC) and critical heat flux (CHF) on the same wicking structure. Here, we present a cost-effective hybrid wicking structure, that can be scalably manufactured using commercial copper micromeshes along with simple etching processes, to enable a novel capillary-driven liquid film boiling heat transfer by simultaneously improving liquid supply and increasing nucleation sites. The interconnected microchannels between woven mesh layers and the substrate serve as low flow resistance passages for high volumetric flow rate of the liquid. Through creating nanograsses and microcavities on the multilayer micromeshes, the liquid flow is enhanced for higher CHF due to the increased surface wettability. Moreover, a plural of microcavities on the mesh surface decrease the superheat for early onset of nucleate boiling (ONB), resulting in higher HTC. Enhanced CHF (198.6 W/cm2) and HTC (138.7 kW/m2 K) are observed on the hybrid mesh wicking structure with a 10 mm × 10 mm heated area due to more than twice the flow rate for liquid supply and more than one third reduced superheat at the ONB, compared to that on the plain mesh wicking structure. The insights gained from this study can be used to guide the design and manufacturing of highly efficient wicking structures in heat pipes, vapor chambers, and other high flux thermal systems. [Display omitted] •A low-cost hybrid wicking structure fabricated using commercial copper woven micromeshes along with simple etching processes.•A novel capillary-driven liquid film boiling with both improved liquid supply and increased nucleation sites.•Unprecedented heat transfer enhancement including a CHF of 198.6 W/cm2 and a HTC of 138.7 kW/m2 K.