Experimental and numerical study of microchannel unit integrated with silicon nanowires and cavities on flow and heat transfer characteristics

High heat flux in miniaturized electronic and energy systems creates an increasing demand for compact and efficient microscale cooling strategies. However, improvements based on a single design factor reach a performance plateau (ceiling effect), highlighting the need for coupled optimization of surface properties and internal geometry. To address this issue, we investigate a novel microchannel configuration that integrates silicon nanowires (SiNWs) coatings with different micro cavities such as rectangular cavities and teardrop-shaped cavities over a Reynolds number range of 0–600. All microchannels are fabricated through a standard semiconductor process and metal-assisted chemical etching method. A uniform SiNWs coating is characterized by a quantitative grayscale analysis with a relative mean absolute deviation of 0.86%. The introduction of rectangular cavities reduced the heat transfer coefficient at high flow rates because of vortex destabilization, whereas the SiNWs coating alone provided only marginal enhancement in flow and heat transfer performance. Among all tested configurations, the teardrop-shaped cavity coated with SiNWs exhibits the most favorable performance, achieving a 25.45% reduction in flow resistance and a 16.14% enhancement in heat transfer, corresponding to a 27.81% increase in the overall performance evaluation criterion compared to the smooth microchannel. These findings demonstrate that the synergistic optimization of surface wettability and micro structure is essential to unlock the full thermal potential of microchannel cooling systems.