Multi-fluid Subdued Boiling; Theoretical Analysis of Multi-fluid Interface Bubbles

The recently discovered boiling phenomenon called “multi-fluid subdued boiling” is discussed. It has been observed that when a beaker containing two immiscible liquids of dissimilar densities is heated at the bottom, the vapor bubbles rise in the lower liquid until they reach the liquid-liquid interface. There the bubbles are trapped, and after a short period of time they collapse. As the heat transfer is increased, however, the bubbles begin to coalesce to form a new set of “interface bubbles,” and the latter eventually become large enough to break away from the interface and rise into the upper liquid layer. Upon reaching the liquid-air interface most of the bubbles do not escape into the ambient but suddenly condense, contract and drop back toward the lower liquid level. “Boiling off,” or net vapor generation, is subdued. The prediction of the interface bubble sizes is also discussed. Analysis shows that the properties of the fluids used can be included mathematically in nondimensional parainetric forms, by means of which the shapes and sizes of the interface bubbles can be found.