Abstract
It is known that violent boiling (i.e., geysering) of liquid sometimes occurs in a device with a long, heated vertical tube. In this study, we experimentally investigated the mechanism of geysering in a vertical small-diameter glass tube heated by a cartridge heater. We also investigated the effects of the water temperature of the upper plenum, the heat input into the boiling vessel and the water depth of the upper plenum on the occurrence condition of geysering. The experimental results showed that when the water temperature of the boiling vessel reached saturation, which included the effect of the hydrostatic head, the superheated water in the vessel suddenly vaporized and geysering occurred. Measurements of differential pressure showed that in the process of geysering, the two-phase flow pressure drop in the vertical tube was almost constant. Although the period of geysering became quite irregular at a high heat input, the periods of regular geysering correlated with the delay time for boiling, τ, indicating the period required for the boiling of subcooled water flowing into the boiling vessel.
