Radius effect on the thermal resistance of disk-shaped thin vapor chambers (TVCs) using Al2O3 nanofluids

Abstract

This paper theoretically and experimentally investigates the radius effect on the thermal resistance of the disk-shaped thin vapor chamber (TVC) using Al2O3 nanofluids as the working fluid. Silicon wafer-based TVCs with a radius of 5 mm, 7.5 mm, and 10 mm are fabricated using both Deep Reactive Ion Etching (DRIE) and ionic bonding. The water-based Al2O3 nanofluids as the working fluid for the TVCs are manufactured by the modified two-step method using a nanodisperser. The thermal resistances of the manufactured TVCs are experimentally measured using a laser heat source and an IR camera to eliminate the thermal contact resistance between the heat source and the TVCs. Based on the experimental results it is shown that the thermal resistance of the nanofluids TVC is decreased up to 56% compared with a TVC with the DI-water. Especially, the effects of the TVCs’ radius and the nanofluids’ volume fraction on the thermal resistance of TVCs are experimentally presented. In addition, it is observed that the nanoparticles’ layer is mainly formed on the sidewall of the pin-fin wick at the evaporator of the TVCs. Finally, we theoretically develop a thermal resistance model for the TVCs considering the nanoparticles’ layer formed on the sidewall of a pin-fin wick structure. It is shown that the experimental data are well matched with the theoretical results presented by the model.