Enhanced Transient Pool Boiling of Water on Nanoscale Textured Superhydrophilic Surfaces
The effects of surface superhydrophilicity on transient pool boiling of water under atmospheric pressure were experimentally examined by means of the quenching method with hot stainless steel spheres. As a baseline case for comparison, the original clean surfaces were determined to have an apparent static contact angle of approximately 23???? that was considered hydrophilic. The superhydrophilic surfaces were prepared by coating the original surfaces with a nanoscale textured layer that further lowers the surface wettability to nearly 0????. The results showed that boiling heat transfer for the superhydrophilic case is enhanced for all the boiling regimes during quenching, as compared to the original hydrophilic case. The critical heat flux was found to improve by 66%. With the aid of high-speed imaging, the absence of a stable vapor film, accompanied by violent rewetting of the superhydrophilic surfaces, was attributed to such great boiling heat transfer enhancement.