Evaporation characteristics of a liquid droplet on oxi-nitriding surfaces.

The present study aims to experimentally investigate the evaporative heat transfer characteristics of a sessile droplet on the oxi-nitriding surfaces which have been widely used for protection of surface corrosion. However, the thermal resistance effect may be substantial with the increase in coating layer thickness. Thus, the basic heat transfer characteristics of oxi-nitriding surface are examined in the present study, especially for droplet evaporation at different surface temperatures. In our experiment, the successive images were captured by using the CMOS camera during evaporation with considering the variation of wettability and temperature. The surface temperature was set from 20°C to 80°C, below the saturation temperature of seawater. From the observation, it was found that the total evaporation time slightly increased due to the inhibited heat transfer caused by the formation of nitriding layer, showing a maximum difference of 10 % approximately between the bare and oxi-nitriding surfaces. It shows almost equal performance of heat transfer, indicating such as the possibility that the oxi-nitriding surface can be applied to such thermal facilities exposed to the corrosive environments.