| Abstract: | Results from an experiment to study boiling phenomena in a channel containing pressurized He II are presented as a function of temperature, pressure and orientation with respect to gravity. The experimental apparatus is made of glass to allow visual observations and high-speed motion pictures to be made of boiling events. Visual data are combined with temperature and pressure measurements to characterize the boiling behaviour and to group the phenomena into boiling regimes. Results are presented in the form of heat transfer regime maps, temperature and pressure traces during boiling, and sketches of the helium vapour and liquid in the channel. One unexpected result is the observation of a macroscopic region of He I with He II below and vapour above. The two interfaces are clearly visible. Another unanticipated result is that the boiling phenomena are often characterized by the periodic production, growth and collapse of vapour even though the heat input is constant. |
