An experimental device for visual measurement of U-shaped tube backflow characteristics

Abstract

The invention discloses a U-shaped pipe backflow characteristic visualization measurement experiment device, which includes primary side equipment and secondary side equipment. The mouth chamber and the outlet are connected, and the U-shaped heat transfer pipe is placed in the cooling water tank of the secondary side equipment. The inner diameter of the visualized pipe is equal to the inner diameter of the U-shaped heat transfer pipe and the tracer storage device is connected to the visualized pipe. The water temperature of the primary side equipment is at least 80 degrees higher than the water temperature in the cooling water tank. The special structure of the U-shaped heat transfer tube and the heat exchange between the first and second sides form a reverse gravity pressure drop, which provides the necessary boundary conditions for the occurrence of the backflow phenomenon of the U-shaped heat transfer tube; the output of the U-shaped heat transfer tube The visualized pipes with the same inner diameter are connected at the end to realize the visualization of the internal flow of the U-shaped heat transfer tube, which solves the problem that the U-shaped heat transfer tube is hidden in the secondary side cylinder and cannot observe the backflow phenomenon, and the accuracy of the simulation is high.

Description

technical field [0001] The invention relates to the technical field of reactor thermal hydraulics and safety, in particular to an experimental device for visually measuring the backflow characteristics of a U-shaped tube. Background technique [0002] The new generation of nuclear power plant reactors generally adopt passive safety technology, which realizes the natural circulation of coolant to continuously export the heat from the core under accident conditions, which significantly improves the inherent safety of the reactor. However, existing studies have shown that under the condition of natural circulation and low flow rate, the parallel U-shaped tube bundles on the primary side of the reactor primary circuit saturated steam generator will have a backflow phenomenon, that is, the coolant passes through part of the U-shaped tube bundle from the outlet chamber of the steam generator. The pipe returns to the inlet chamber, which reduces the heat exchange area of ​​the stea...

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Problems solved by technology

However, existing studies have shown that under the condition of natural circulation and low flow rate, the parallel U-shaped tube bundles on the primary side of the reactor primary circuit saturated steam generator will have a backflow phenomenon, that is, the coolant passes through part of the U-shaped tube bundle from the outlet chamber of the steam generator. The pipe returns to the inlet chamber, resulting in a reduction in the heat exchange area of ​​the steam generator and an increase in flow resistance, which is not conducive to the operation of the steam generator and the reactor system under natural circulation conditions

Due to the complex structure of the steam generator, and the U-shaped tube is located in the pressure-bearing chamber of the secondary side, it is impossible to directly observe and accurately identify the backflow phenomenon. Currently, the temperature change of the fluid is usually monitored by means of thermocouples with limited inlet and outlet. In order to identify the occurrence of the backflow phenomenon, because this method can only arrange the thermocouple in the U-shaped tube on the outer side of the steam generator, the thermocouple cannot be placed in the U-shaped tube inside the steam generator, so only the steam generation can be monitored The backflow phenomenon in the U-shaped tube outside the steam generator cannot be identified.

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