Experimental study on heat transfer and pressure drops in sodium boiling in a vertical tube

An experimental investigation of sodium boiling in a vertical tube under conditions of forced lifting flow has been accomplished. The study of heat output and pressure losses has been made during sodium boiling in a tube 710 mm in length and 4.98 mm in diameter. Two methods eliminating spontaneous migration of the simmering point along the boiling channel were used: introduction of inert gas to the process section inlet, and establishment of artificial vaporization centers - cavities of the ''vessel'' type. The heat output and pressure losses have been studied in the heat flux density range of 0.2 to 1.1 MW/m2, mass velocities of 150 to 400 kg/m2s, mass vapor contents of max. 0.45, pressures of 0.1 to 0.2 MPa. The high heat output coefficients measured confirm the author hypothesis about zero boiling conditions in the sodium film flowing along the tube wall. From the view point of engineering practices, the small wall/liquid temperature differencies imply that the thermal resistance between the wall and diphase sodium flow can be neglected in design engineering