Session: 04-04: Nano/Microscale Boiling and Condensation Heat Transfer

Paper Number: 133006

133006 - Superhydrophilic Composite Structure of Copper Micro-Pin-Fins and Nano-Forest for Enhancing Boiling Heat Transfer 

Abstract: 

Excessive temperature is one of the main reasons for the failure of electronic components. As the heat flux density of electronic components continues to increase, in order to ensure the normal operation of electronic components, higher requirements are put forward for heat dissipation. Therefore, the research on heat dissipation is very important. Compared with the previous cooling methods based on single-phase heat transfer, boiling heat exchange that uses phase change latent heat to absorb heat has better heat transfer performance. In boiling heat exchange, compared with active boiling heat exchange, passive boiling heat exchange does not require additional external energy acquisition. The device is simpler, the cost is lower, and it is more suitable for small equipment such as electronic components. Pool boiling in passive heat exchange has extremely high energy conversion efficiency, so this paper studies the enhanced heat transfer of pool boiling. This paper designed and prepared copper micro-pin-fins substrates with different characteristic sizes. Nanostructures are then made on the micro-pin-fins through a simple one-step electrodeposition process, which looks like a natural forest structure with rich branch-like grooves. Capillary rise tests were performed with ethanol to characterize the capillary force of the wick structure. In addition, pool boiling experiments were conducted on different surfaces at different degrees of subcooling using HFE-7100 as the cooling fluid, and the experimental results and the boiling heat transfer phenomenon on the surfaces were analyzed. An efficient boiling heat transfer (BHT) interface based on a superhydrophilic copper micro-pin-fins and nano-forest composite structure is reported. In principle, these micro-pin-fins are efficient nucleation sites, helping to reduce the surface superheat required for the onset of nucleate boiling (ONB) and enhance the heat transfer coefficient (HTC). Disperse nano-forest contribute to bubbles detachment from the heated wall rapidly. Micro-pin-fins with a depth of a few hundreds of microns can avoid excessive interface thermal resistance, the superwetting effect of the micro-nano composite structure helps to increase the critical heat flux (CHF). By studying the morphology, wettability, liquid subcoolings and heat transfer characteristics of the micro-pin-fins and nano-forest composite structure as a function of growth time, an optimal interface was obtained, with a maximum HTC enhancement of 243%, CHF enhancement of 204%, and the superheat corresponding to the ONB compared to the flat copper surface is reduced by 50%. At the same time, the combination of experimental and theoretical analysis also clarified why the micro-pin-fins and nano-forest composite structure on the copper surface can effectively enhance boiling heat transfer. This work not only broadens the application scope of superwetting surfaces, but also provides new insights into how to rationally design superhydrophilic micro-nanostructures to achieve more efficient boiling heat transfer.

Presenting Author: Xiang Ma School of Chemical Engineering and Technology, Xi’an Jiaotong University

Presenting Author Biography: Ma Xiang received a master's degree in energy and power engineering from Qingdao University of Science and Technology in 2020. He is currently studying for a PhD in energy and power engineering at Xi'an Jiaotong University. He has won national scholarships and first prizes in innovation competitions. His research interests include micro- and nanoscale boiling heat transfer, thermal management of electronic devices, heat pipes, etc.

Authors:

Xiang Ma School of Chemical Engineering and Technology, Xi’an Jiaotong University
Yonghai Zhang School of Chemical Engineering and Technology, Xi’an Jiaotong University
Xiaoping Yang School of Chemical Engineering and Technology, Xi’an Jiaotong University
Jinjia Wei School of Chemical Engineering and Technology, Xi’an Jiaotong University