CN-121762619-B - Visual critical heat flux density test method and device

CN121762619BCN 121762619 BCN121762619 BCN 121762619BCN-121762619-B

Abstract

A visual critical heat flow density test method and a device belong to the field of thermal hydraulic tests. The visual critical heat flux density test method comprises the following steps of providing a CHF test device with a transparent heater, synchronously collecting infrared signal distribution data and bubble distribution image data of the transparent heater, establishing a heat conduction/radiation heat transfer coupling model of the transparent heater, calculating temperature distribution data of a transparent heating film according to the infrared signal distribution data, combining the surface temperature distribution data of the transparent heating film with the bubble distribution image data, and determining the position where boiling phenomenon occurs in the test process and the temperature of the transparent heating film at the corresponding moment. The method can effectively improve the accuracy of the CHF visual test.

Inventors

LIU RUIYANG
TANG CHUNTAO
WANG XIUJIA
LIU DI
MINAMI TAKAAKI
QI ZHANFEI
ZHANG HUANG
YAN YAN
Yang Haikuo
WANG HAITAO
ZHANG KUI
WEI CEN
YIN HUAQIANG

Assignees

上海核工程研究设计院股份有限公司

Dates

Publication Date: 20260508
Application Date: 20260304

Claims (9)

1. The visual critical heat flux density test method is characterized by comprising the following steps of: providing a CHF test device, wherein the CHF test device comprises a simulation flow channel and a transparent heater, the simulation flow channel is internally provided with flowing cooling water, the transparent heater is arranged on the wall body of the simulation flow channel and comprises a transparent substrate and a transparent heating film, and the transparent heating film is arranged on one side of the transparent substrate facing into the simulation flow channel; Step b), collecting infrared signal distribution data of the transparent heater and bubble distribution image data of the surface of the transparent heating film, and performing time synchronization on the infrared signal distribution data and the bubble distribution image data; Step c), establishing a heat conduction/radiation heat transfer coupling model of the transparent heater, calculating to obtain infrared radiation intensity distribution of the transparent heating film according to the heat conduction/radiation heat transfer coupling model and the infrared signal distribution data, further calculating to obtain temperature distribution data of the transparent heating film, , X, y, z are space coordinates in a rectangular coordinate system, z is the thickness direction of the transparent heating film, xy plane is the plane of the transparent heating film, t is time, λ is wavelength, λ 2 -λ 1 is the infrared wavelength range of measurement, For the distribution of the infrared signal(s), For the infrared radiation signal intensity of the transparent heating film, As the intensity of the background infrared radiation, For the system equivalent apparent transmittance of the transparent heater, To monotonic mapping operators defined based on solid thermal conductivity, Is that Is used as a function of the inverse function of (c), For the temperature distribution of the transparent substrate, z c is the thickness of the transparent substrate, A h is the area of the transparent substrate, V (t) is the voltage of the transparent heater, l (t) is the current of the transparent heater, The temperature distribution data of the transparent heating film is obtained by coupling solving calculation according to the boundary condition of the transparent heater based on the heat conduction process and the heat radiation process; and d) determining the occurrence position of the boiling phenomenon of the cooling water in the test process and the temperature of the transparent heating film at the corresponding moment based on the temperature distribution data of the transparent heating film and the bubble distribution image data.
2. The method according to claim 1, further comprising a calibration step of heating the transparent heating film and collecting infrared signal distribution data of the transparent heater in a state where the cooling water is not filled in the simulation flow channel, and in the step c), verification calculation is performed on the temperature distribution data of the transparent heating film based on the result of the calibration step.
3. The method for testing the visual critical heat flux density according to claim 2, wherein the method for verifying calculation is characterized in that in the calibration step, the transparent heating film is enabled to reach a given temperature, infrared photons emitted by the transparent heater are counted by an infrared camera, an infrared photon count-temperature steady-state curve is established, in the step c), the infrared camera is utilized to acquire local distribution of infrared photon counts emitted by the transparent heater in a given time step, the local temperature of the transparent heating film is predicted and calculated according to the local distribution of the infrared photon counts, the temperature distribution of the transparent substrate is calculated according to a boundary condition and a heat conduction relation, the total infrared radiation intensity of the transparent heater is converted into an infrared photon count, the infrared photon count result acquired by the infrared camera is compared, parameters in the heat conduction/radiation heat transfer coupling model are updated when the error exceeds a given threshold value, and iterative calculation is performed until the error does not exceed the given threshold value.
4. The method according to claim 1 or 2, wherein in the step a), the transparent heating film is opaque in a wavelength band of 3 μm to 5 μm.
5. The method according to claim 4, wherein in the step a), the transparent heating film is an indium tin oxide film, and the transparent substrate is sapphire, aluminum oxynitride or quartz glass.
6. The method according to claim 1 or 2, wherein in the step a), the transparent heaters are respectively provided to a pair of walls of the dummy flow path.
7. A visual critical heat flux density testing device, which is used for the visual critical heat flux density testing method as set forth in any one of claims 1 to 6, and comprises an analog runner, an infrared camera, a high-speed camera and a data processing device; Wherein, the At least part of the wall body of the simulation flow channel is provided with a transparent heater, the transparent heater comprises a transparent matrix and a transparent heating film, the transparent heating film is arranged on one side of the transparent matrix facing the simulation flow channel, and flowing cooling water is provided in the simulation flow channel; the infrared camera collects infrared signal distribution data of the transparent heater; The high-speed camera collects bubble distribution image data of the surface of the transparent heating film through the transparent heater; The data processing device is in signal connection with the analog flow channel, the infrared camera and the high-speed camera, and determines the position and the corresponding temperature of the cooling water boiling phenomenon based on the infrared signal distribution data and the bubble distribution image data.
8. The visual critical heat flux density testing apparatus of claim 7, wherein the transparent heaters are respectively provided on a pair of walls of the analog flow channel.
9. The visual critical heat flux density testing apparatus as set forth in claim 7 or 8, wherein the data processing apparatus comprises a synchronization triggering module, a memory and a processor, the synchronization triggering module time-synchronizes the infrared signal distribution data with the bubble distribution image data, the memory stores a calculation program, and when the calculation program is executed by the processor, the calculation process in step c) and step d) in the visual critical heat flux density testing method as set forth in any one of claims 1 to 6 can be implemented and the calculation result is outputted.

Description

Visual critical heat flux density test method and device Technical Field The invention belongs to the field of thermal hydraulic tests, and particularly relates to a visual critical heat flow density test method and device. Background In nuclear engineering, high heat Flux heat exchange structures and related research fields, critical heat Flux density (CRITICAL HEAT Flux, CHF) is one of the main parameters for evaluating the thermal safety margin of a system, and its magnitude is directly related to the fuel cladding temperature level, the coolant heat transfer capability and the safety margin under accident conditions. Therefore, the accurate acquisition and prediction of the critical heat flux density have important significance for engineering design, safe operation analysis and accident prevention of the nuclear reactor. The heat exchange structure with rectangular or annular narrow-gap flow channels is widely adopted in advanced nuclear energy systems such as high-flux research stacks, small modular reactors and other heat exchange equipment with heat transfer and exchange functions, and the flow channel form has obvious advantages in engineering application, namely, on one hand, the flow channel form realizes equipment miniaturization and structure compactness through a higher specific surface area, and fits the strict constraint of the nuclear energy system on the volume and arrangement space, and on the other hand, the manufacturing process of the structural form is relatively mature, so that the structural form is convenient for processing and forming. The structure has the remarkable advantages of high heat exchange efficiency, large effective heat exchange area, deep fuel burn-up, compact structure and the like, and can meet the strict requirement on cooling performance under the condition of high power density. For the research of critical heat flow density, the development of a simulation test is still highly dependent at present, cooling water is heated by a simulation heating device under the test environment until CHF phenomenon occurs, and the position where the CHF occurs and various physical parameters in the test process are measured. Currently, CHF tests generally rely on invisible temperature measurement, the measurement result is highly dependent on the arrangement position and density of a temperature sensor (the arrangement distance of thermocouples can reach cm level generally), the wall surface temperature field in the test process is difficult to accurately obtain, and the non-uniform evolution process of the thermal load in space when CHF occurs is difficult to characterize. Some technical schemes attempt to introduce technical means such as infrared thermal imaging and the like to carry out visual measurement on the CHF process, but infrared measurement signals in the test process are simultaneously influenced by heat conduction in the wall, surface radiation characteristic change and coupling of coolant side convection and phase change heat exchange, so that obvious deviation exists between apparent temperature obtained by infrared measurement and real wall temperature. In addition, in the existing visualized boiling and CHF experiments, the wall heat flux density is generally calculated by averaging the input electric power and the nominal heating area, and the method can only obtain the whole average heat flux density per se, so that the non-uniform heating characteristics of the inner wall surface of the narrow rectangular flow channel in the flow direction and the transverse direction are difficult to reflect, and particularly, the key characteristics of the evolution of the local area heat load in time and space before the critical heat flux density occurs cannot be characterized. The measurement means such as visual measurement and heating electrical parameter collection generally run independently, and a unified time synchronization and data association mechanism is lacked, so that accurate corresponding analysis between different physical quantities on the same time scale and space position is difficult to carry out, and further a reliable quantitative association relation between wall surface thermal behaviors and vapor-liquid two-phase flow behaviors is difficult to establish. Therefore, the test method capable of accurately calculating the critical heat flux density related parameters based on the visual test has positive significance for improving the accuracy and reliability of the visual critical heat flux density test. Disclosure of Invention A visual critical heat flow density test method is provided to improve the accuracy of CHF visual test. The invention further provides a critical heat flux density calculating device based on the visual test. According to an embodiment of one aspect of the present invention, there is provided a visual critical heat flux density test method comprising the steps of: providing a CHF test device, wherein the CHF test device co