HEAT-TRANSFER IN BUBBLE LAYERS AT ELEVATED PRESSURES

Heat transfer with steam condensation under moderate pressure on the s urface of a horizontal tube immersed in a bubbling layer was experimen tally investigated. A copper test section 16 mm in outer diameter and 400 mm in length was placed in a bubbling column 455 mm in diameter. E xperiments were made under pressures of 0.14-0.8 MPa, with void fracti on 0.04-0.23, vapor superficial velocities 0.05-0.42 m/s, liquid-wall temperature differences 47-105 K, and heat flux densities 0.12-0.8 MW/ m2. The heat transfer process in the bubbling layer is shown to be of a high intensity: with moderate values of steam content, heat transfer coefficients reach 12-14 kW/(m2 . K). Data obtained showed that the k nown correlations do not consider the influence of pressure on heat tr ansfer. For the first time, data on radial steam content distribution under pressures higher than atmospheric were obtained by an electropro be method. A table of experimental data is presented.