Experimental study on the saturated pool boiling heat transfer on nano-scale modification surface

Plain nickel foil surface, three kinds of plain nickel-based chemical treatment surfaces and four kinds of nickel-based electrochemical treatment surfaces with nano-cone array structure were used in the pool boiling experiment. The quantitative effects and the effect mechanism of the surface characteristic parameters, including nano-scale roughness (Ra), solid–liquid contact angle (CA) and effective heat transfer area ratio (r: the ratio of the actual heat transfer area and its projected area) on the heat transfer coefficient (HTC) on the modification plain surfaces and nano-cone array surfaces were studied and summarized. By improving the previous proposed the HTC prediction correlation for the common plain surfaces (without considering the effect of r), a new uniform correlation is proposed and it can well predict the HTC of the heated surface with simple convex structure (with considering the effect of r). In addition, the bubble dynamic characteristics including the bubble departure diameter, the bubble departure frequency, the active bubble nucleation site density and the combined bubble were investigated by visualization research. These results proposed some mechanism support for the new predicting correlation.