APPLICATION OF FLOW PATTERNS AND ACCOUNTING OF HYDRODYNAMIC EFFECTS IN THE COURSE OF UPGRADING DISTRIBUTION HEADER SYSTEMS OF NPP HEAT EXCHANGERS AND REACTORS

The article deals with application of flow patterns and hydrodynamic effects in the course of upgrading distribution header systems (DHS) used in heat exchangers and reactors of nuclear power plants (NPP). Consideration is given to four typical axisymmetric DHSs of flat and cylindrical types, which differ in the ways of fluid supply to the collector and its removal from it. The schematic diagrams of flow patterns are shown for different DHS designs of the cylindrical types with central and lateral fluid inlets of the collector. Besides, the water flow pattern is given for the flow path of various DHS designs of a flat type, also with central and lateral fluid inlets of the collector. Hydrodynamic features of the fluid flow in the DHS have been analyzed. It is shown that in a restricted and free DHS the coolant flow is of a jet nature. The fluid flow in the header is characterized by transformation of some types of jets into others, by the presence of eddy and stagnant zones. The designs of heat exchangers and reactors for nuclear power plants with the considered typical DHS characteristics implemented are presented. The DHS designs upgraded with the use of the indicated patterns and effects are demonstrated. The revealed regularity of liquid distribution at the outlet of the DHS flow paths and the hydrodynamics identity property for axially symmetric DHS with flow reversal are analyzed.