Pool boiling enhancement in electrodeposited copper capillary wicks: Staggered pore configuration versus straight through-hole design

Electrodeposition enables the fabrication of micro-nano hybrid porous materials, significantly enhancing boiling heat transfer (BHT) performance. This study produced two distinct copper capillary wicks by controlling copper ion concentration in the electrolyte: a multi-layer porous wick (Sample#M) with staggered pores in the hundreds of micrometers, and a single-layer wick (Sample#S) featuring straight through-holes of similar size. Both structures exhibit porous walls composed of submicron to micron-sized dendrites. Boiling heat transfer experiments reveal that Sample#S achieves an h_MNB of 29.4 W/(cm²·K) at 300 W/cm², 1.4 times that of Sample#M and 5.25 times that of smooth copper (Sample#O). Sample#S also demonstrates a CHF of 310 W/cm², 121 % and 270 % higher than Sample#M and Sample#O, respectively. Capillary tests and bubble dynamics analysis indicate that Sample#S's superior performance stems from its non-interleaved liquid transport channels, enabling faster liquid replenishment, and its through-hole design, which reduces bubble departure resistance, resulting in higher departure frequency and radius for enhanced heat transfer.