536.423.4 Stationary heat transfer to a heat-absorbing surface during upward motion of a low-velocity steam-water flow (W 0 < 1.2 m/sec) or bubbling of steam is studied. This form of heat transfer is characteristic for water-cooled passive heat-removing systems with a long operating time and different emergency-use heat exchangers at nuclear power plants. In [1] it is shown that the intensity of this type of heat transfer is high: <~ = 8-15 kW/(m2-K). This is much higher than the value of