Relation between temperature fluctuation of a heating surface and generation of drypatch caused by a cylindrical spacer in a vertical boiling two-phase upward flow in a narrow annular channel Original Research Article

When a flow obstruction such as a cylindrical spacer is set in a boiling two-phase flow within an annular channel, the inner tube of which is used as a heater, the temperature on the surface of the heater tube is severely affected by the existence of the cylindrical spacer. In some case the cylindrical spacer has a cooling effect, and in the other case it causes the dryout of the cooling water film on the heating surface resulting in the burnout of the tube. In the present paper we will discuss the temperature distributions near the cylindrical spacer and its fluctuation characteristics in relation to the change of the flow configuration near the cylindrical spacer.