Boiling heat transfer characteristics have been experimentally investigated in a channel opened at both ends to a pressurized (1atm) He II bath. Different trends in temperature fluctuation in the channel were observed between the cases when a heat transfer surface is facing upward and downward. This difference in characteristics is considered to be caused by a flow of helium in the channel which is induced by a flow of bubbles. Values of overall heat transfer coefficient between the heat transfer surface and the He II bath indicate a cooling ability of the He II channel quantitatively.
