Boiling heat transfer on surfaces with 3D-printing microstructures

We fabricate plane surface and surfaces with different microstructures, such as coral-rock, star-like, and inner-fin structures, for boiling heat transfer, through 3D microprinting. The thickness of the surfaces is 1.3 mm, while the maximum depth of the microstructures reaches 0.9 mm. With these surfaces, subcooled boiling and saturated nucleate boiling of de-ionized water are carried out, respectively, by applying different heating voltages from 50 V to 105 V. The experimental results show that the boiling heat transfer could be weakened by the entrapped vapor in the microstructures. The heat flux on the microstructures decreases with the increase of real surface area in subcooled boiling because of the increase of the entrapped vapor thickness in the microstructures. However, during the saturated nucleate boiling, the surface with inner-fin structure has higher heat flux than that with star-like structure, due to the generation of more nucleation sites in inner-fin structures.