Abstract: “Wetting phenomena are very important in industrial and chemical fields. As the scale of the system becomes small, the surface interaction becomes dominant because of the increasing surface-to-volume ratio, which, for example, affects the morphological characteristics of the flow patterns in microchannels. This means that the control of wettability leads to efficient heat transfer and chemical reactions and so on. Especially, in space, the wetting phenomena are crucial. Therefore, development of the efficient heat exchanger is important because the major heat exchange is radiation. However, there are many unresolved problems with respect to the wetting phenomena such as contact angle hysteresis and size dependency of the contact angle, not to mention the wetting phenomena under zero-gravity condition. In the present study, the wettability of micro and millimeter seized droplets on lowsurface- energy solid is evaluated experimentally and theoretically. The fundamental behavior of the dro”

Keywords: wetting phenomena, contact angle, gravity effect on wettability, droplet