Mitigating the thermo-hydraulic trade-off in ice-slurry flow using nanostructured superhydrophobic surfaces

Nanostructured superhydrophobic (SHB) interfaces offer a promising route to regulate phase-change slurry transport by reducing wall adhesion and hydraulic resistance while enhancing near-wall heat transfer. Ice slurry is a phase-change cold-energy carrier that combines convective transport with latent-heat absorption, but its practical use is limited by the trade-off between heat-transfer enhancement and hydraulic penalty. In this work, we experimentally investigated ice-slurry flow in channels with plain copper and nanostructured SHB surfaces. Relative to single-phase water on the plain surface, ice slurry increased the Nusselt number ( Nu ) by ∼8–28% but also raised the pressure drop by approximately 5–8 times, highlighting the intrinsic thermo-hydraulic trade-off of phase-change slurry transport. The nanostructured SHB surface further improved heat transfer, with Nu increasing by 31–37% relative to the plain surface, while reducing pressure drop by ∼9%, 22%, and 14% at ice packing factors of 5%, 10%, and 15%, respectively. These benefits are attributed to particle-induced thermal-boundary-layer disruption, phase-change-assisted heat absorption, and SHB-induced interfacial regulation that reduces wall adhesion and shear resistance. These results demonstrate the potential of nanostructured SHB surfaces for improving the thermo-hydraulic performance of phase-change slurry transport in compact cooling systems.