Liquid film-induced critical heat flux enhancement on structured surfaces

Jiaqi Li; Daniel Kang; Kazi Fazle Rabbi; Wuchen Fu; Xiao Yan; Xiaolong Fang; Liwu Fan; Nenad Miljkovic

doi:10.1126/sciadv.abg4537

Liquid film-induced critical heat flux enhancement on structured surfaces

Sci Adv. 2021 Jun 25;7(26):eabg4537. doi: 10.1126/sciadv.abg4537. Print 2021 Jun.

Authors

Jiaqi Li¹, Daniel Kang¹, Kazi Fazle Rabbi¹, Wuchen Fu¹, Xiao Yan¹, Xiaolong Fang¹, Liwu Fan², Nenad Miljkovic^{3

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Affiliations

¹ Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
² Institute of Thermal Science and Power Systems, School of Energy Engineering, Zhejiang University, Hangzhou 310027, China.
³ Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA. nmiljkov@illinois.edu.
⁴ Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
⁵ Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
⁶ International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan.

Abstract

Enhancing critical heat flux (CHF) during boiling with structured surfaces has received much attention because of its important implications for two-phase flow. The role of surface structures on bubble evolution and CHF enhancement remains unclear because of the lack of direct visualization of the liquid- and solid-vapor interfaces. Here, we use high-magnification in-liquid endoscopy to directly probe bubble behavior during boiling. We report the previously unidentified coexistence of two distinct three-phase contact lines underneath growing bubbles on structured surfaces, resulting in retention of a thin liquid film within the structures between the two contact lines due to their disparate advancing velocities. This finding sheds light on a previously unidentified mechanism governing bubble evolution on structured surfaces, which has notable implications for a variety of real systems using bubble formation, such as thermal management, microfluidics, and electrochemical reactors.

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