Critical heat flux of pool boiling on Si nanowire array-coated surfaces

Pool boiling of saturated water on plain Si surfaces and surfaces covered with a dense array of Si nanowires (SiNWs) has been studied. Measured CHF and heat transfer coefficient (HTC) values of about 223 ± 5.61 W/cm2 and 9 ± 1.60 W/cm2 K, respectively, on the nanowire array-coated surface are among the highest reported in boiling heat transfer. Meanwhile, the CHFs on both nanowire-coated and Plain Si surfaces show a similar heater size dependence – the CHF increases as heater size decreases. The measured CHFs on both types of surfaces are approximately following the prediction of the hydrodynamic theory assuming the Helmholtz wavelength equal to the corresponded heater length. It suggests that the CHFs on both types of surfaces might be limited by pool hydrodynamics.