Enhanced Heat Dissipation of SWCNT-Coated Screws with Built-In Thermoelectric Energy Harvesting

Thermal management limits the performance of densely integrated electronics. Heat-sink surfaces are conventionally passive elements dedicated to heat rejection. Here we show that one conformal single-walled carbon nanotube (SWCNT) coating renders such a surface dual-functional. The coating comprises p- and n-type SWCNT films whose porous, mesh-like network enlarges the effective surface area and raises the emissivity. It converts part of the rejected heat into electricity through the Seebeck effect. We applied the coating to an alumite-insulated aluminum screw, a compact model of an extended heat-sink surface. Under forced convection at 3.0 m/s, the coating lowered the hot-side temperature of the screw by up to 22 K, from 341.8 K to 319.4 K. Cooling was optimal at 75% axial coverage. Repeated runs and an independently fabricated device confirmed this optimum. The apparent heat-transfer coefficient, defined on the total heater input and on the metallic reference area, rose 1.6-fold, from 172 to 278 W/(m2·K). At full coverage, the same layer generated 0.72 mV and 1.0 nW per p–n pair. The cooling optimum and the power optimum occur at different coverages, which yields a practical design freedom. These results recast the surfaces of cooling components as multifunctional, thermally active layers.