Abstract
Boiling heat transfer can be greatly enhanced through careful control of the physiochemical characteristics of contact surfaces. In this work, by utilizing the electrodeposition method, we prepared enhanced metallic surfaces with 3D cubic Cu2O crystals and dendritic copper branch nanostructures. Their static contact angles are 127° and 139°, respectively. Additionally, incipience temperature overshoot at the onset of nucleate boiling decreased to only 4.4 K and 2.9 K from 15.3 K, and the maximum heat transfer coefficients for the conditioned surfaces were improved by 311.4% and 389.2%, respectively. Based on comparative analysis, the effects of nanocavity structure on bubble dynamics and heat transfer mechanisms are explicitly clarified. We determined that deep nanoscale cavities with interconnected branch structures are the key factor for facilitating appreciable capillary force and low seepage resistance to maintain efficient boiling heat transfer. Slender bubbles generated from dendritic structured surfaces effectively mitigate bubble coalescence and delay local vapor film coverage, thereby overcoming the defect of heat transfer deterioration under high heat flux. A surface with a 3D dendritic nanostructured layer can withstand a heat flux up to q = 73.53 W/cm2 without drying out.
Published Version
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