Synergistic enhancement of pool boiling on micro-nanostructured MG-AgNWs hierarchical surface

Surface modification for boiling heat transfer enhancement can boost the operational efficiency of energy systems and resolve thermal management challenges in electronic devices. However, the concurrent optimization of critical heat flux (CHF) and heat transfer coefficient (HTC) remains challenging. This is because it demands a delicate balance between facilitating bubble nucleation and suppressing detrimental bubble coalescence. To address this, concurrent improvement of the two parameters during boiling was achieved by spraying AgNWs (Ag nanowires) synthesized through a modified polyol method onto a microgroove substrate, thereby preparing Ag nanowire-coated microgroove surfaces (MG-AgNWs). The pool boiling characteristics, capillary wicking and bubble dynamics of MG-AgNWs under atmospheric pressure were systematically investigated. The as-prepared MG-AgNWs surface achieves a CHF of 349.9 W cm −2 and an HTC of 26.2 W cm −2  K −1 , corresponding to enhancements of 269.4% and 759.8% compared with the plain copper surface, respectively. Benefiting from the enhanced capillary performance of AgNWs and the excellent nucleation activity of MG, the MG-AgNWs surface exhibited significantly increased nucleation density, reduced bubble departure diameter, and accelerated bubble departure frequency compared with plain copper substrates. Capillary wickability tests on various surfaces demonstrated a strong linear correlation between wicking velocity and CHF. These results confirm that capillary-driven liquid replenishment inhibits dry spot expansion, leading to improved CHF. Collectively, such hierarchical surface presents a viable approach to creating efficient boiling heat transfer surface for advanced thermal control applications.