RESUMO

To further enhance pool boiling heat transfer, a new oscillation device was proposed. An oscillating plate was located over the heater surface with a vertical oscillation amplitude of 20 mm and frequency of 6 Hz. Three N-type phosphorus-doped silicon chips were used as heater surfaces. One was a smooth surface, and the other two were micropin-finned chips with a fin side length of 30 μm and fin height of 60 μm (chip PF30-60), and the pin fins were arrayed with aligned and staggered arrangements, respectively. Absolute ethyl alcohol was used as a working fluid. The results showed that mechanical oscillation can enhance boiling heat transfer in both convective region and high heat flux region. The wall superheat showed a considerable decrease of 20-30°C in the convective region by thinning the thermal boundary layer on the heater surface, and the critical heat flux could also be increased by 20%. In addition, the micropin-finned chips showed better performance due to much more fresh liquid supply from the interconnected tunnels formed by micropin fins, which is driven by capillary force.