Investigation of biphilic microgroove surface on condensation Enhancement : A 3D Lattice Boltzmann method study

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Original languageEnglish
Article number119520
Journal / PublicationApplied Thermal Engineering
Volume219
Issue numberPart B
Online published7 Nov 2022
Publication statusPublished - 25 Jan 2023

Abstract

Condensation heat transfer enhancement is valued in numerous engineering fields for the goal of carbon neutrality. Microgroove surfaces provides a passive approach for sustainable dropwise condensation due to their excellent droplet nucleation and removal ability. Therefore, to elucidate the enhancement mechanisms and determine the optimum microgroove geometry design, a 3D Lattice Boltzmann Method model is developed. A three-layered hybrid boundary scheme is proposed with improved numerical stability. Results show that suction and bridging modes are two major droplet behaviors on microgroove surfaces. The suction mode can accelerate the droplets' sliding-off process and lead to a smaller departure radius, while the bridging mode could deteriorate the enhancement performance by causing strip-like liquid films. Based on theoretical and simulation results, optimum geometry is proposed under the range of 1 ≤ WG ≤ 2, 0 ≤ SG ≤ 2, sin(π-θ)WG + SG > 2sin(π-θ), and D≅ 1 + sin(θ-π/2). The heat flux of the best case is enhanced by 126.9% compared with the result of a plain hydrophobic surface. Furthermore, the enhancement performance of biphilic microgroove surfaces with hydrophilic grooves is discussed. It is found that the suction mode is enhanced while the bridging mode is inhibited, which leads to a superior enhancement performance of 140.4%, even compared with a pure hydrophobic microgroove surface. Finally, surface orientation is studied to analyze the biphilic microgrooves' condensation enhancement. The downward-facing surface can suppress the suction mode inside the hydrophilic regions and enhance direct departure behaviors on the hydrophobic ridge regions. These conclusions provide a valuable guide for surface modification design and unraveling the enhancement mechanisms.

Research Area(s)

  • Condensation, Heat transfer enhancement, LBM, Mechanisms, Surface modification design