Heating rod used for critical heat flux density test

Abstract

The invention discloses a heating rod used for a critical heat flux density test. The heating rod comprises a nickel rod, a heating tube, a nickel tube, a copper tube, a ceramic member, copper sheets and thermocouples. The heating tube, the nickel tube and the copper tube are fixedly connected in a butting and sealing way in turn so as to form a rod body with a hollow structure. The nickel rod is connected with external upper live equipment. The copper tube is connected with external lower live equipment. The ceramic member is attached to the internal wall of the rod body and surrounds so as to form a heat cavity. The copper sheets are evenly and transversely arranged in the heat cavity and positioned in the heating tube. The thermocouples are arranged in the heat cavity in a suspension way and fixed by the copper sheets. The heating rod used for the critical heat flux density test is high in heating temperature, high in heat flux density and compact in structure so that the requirements of the critical heat flux density test can be met. Besides, temperature parameters are measured and outputted via the thermocouples in real time so that simulation of nuclear fuel heat release can be accurately realized and the requirements of the critical heat flux density test can be effectively met, critical heat flux density of a nuclear fuel rod under different operation conditions can also be measured, and thus the heating rod used for the critical heat flux density test has a great supporting effect for research and development of new type of nuclear fuel assemblies.

Description

technical field [0001] The invention relates to the field of nuclear reactor test research, in particular to a heating rod used for studying critical heat flux density tests of nuclear fuel assemblies. Background technique [0002] In convective boiling, there are mainly two types of critical heat flux: deviating nucleate boiling and dry out. In the steady-state thermal design of PWR nuclear power plant, usually only subcooled boiling and saturated boiling with low vapor content are encountered, so the heat flux away from nucleate boiling is particularly important. [0003] The mechanism model of deviating nucleate boiling mainly includes three types: (a) when a large steam bubble is formed on the wall of the heating element, the thin liquid film at the bottom evaporates continuously, forming dry spots, which leads to the deterioration of heat transfer on the wall of the heating element; (b) ) When the bubble layer on the wall of the heating element is thick enough to preve...

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Problems solved by technology

[0008] U.S. Patent US4156127 also discloses an electric heating rod, which is composed of three extruded layers, the inner layer is a thin polytetrafluoroethylene tube, which plays the role of insulation and heat exchange with the medium; the middle layer is made of carbon and polytetrafluoroethylene The mixture of ethylene conducts heat and conducts heat; the outermost layer is a polytetrafluoroethylene thick tube, which acts as insulation and heat insulation from the environment; the wires connected to the middle layer are drawn out from the beginning and end of the heating rod. When a voltage is applied to the wires, it will A current flows through the middle layer of evenly arranged carbon materials, thereby generating uniform heat generation; therefore, the electric heating rod can generate heat evenly distributed along the axial direction, but the maximum temperature can only reach 260°C, which is far below the critical heat flux test. The required temperature; the heating layer and the medium are insulated and conducted through polytetrafluoroethylene, which cannot achieve rapid and large-scale heat exchange; the diameter of the electric heating rod is large, and it cannot be processed and assembled according to the size of nuclear fuel

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