Abstract
Various boiling heat transfer characteristics have been experimentally investigated in a vertical channel opened at both ends to a pressurized (1 atm) He II bath. A wire heater is attached at the center of the rectangular cross-sectional channel. In the boiling states, the removed heat through the upper side of the channel increases with the increase of input power to the heater, while the removed heat through the lower side of the channel is kept constant. A temperature rise in the channel when the aspect ratio of the channel cross section is 1 is smaller than that when the aspect ratio of 7 after He II to He I transition occurs. The critical values of heat flux at which He II to He I and nucleate boiling to film boiling transitions occur in the vicinity of the heater surface in this channel are larger than those in a channel closed at the bottom, respectively.
