We employed the recent micro machining technology on the heating surface and produced the artificial micro-ordered groove pattern. The frost phenomena on the artificial surface with micro-structure are experimentally investigated. The effects of the groove depth or pattern pitch on the frost characteristics were focused. In addition, the effects of the wall wettablity by changing the surface treatment with water-repellent or water-attracting were also tested. The direct observations for the frost and its melting phenomena on the surface were carried out by using the digital microscope with high spatial resolution. It is cleared that the grooves on the surface strongly affect the frost phenomena, especially the generation of the super-cooled droplets on the surface, which can be observed at the beginning of cooling. The water drainage after frost melting was also affected by the micro grooves and wettability on the surface.
