A determinant conductance probe system and liquid film thickness measurement method suitable for annular flow liquid film thickness measurement in narrow rectangular channels

Abstract

The object of the present invention is to provide a determinant conductance probe system and a liquid film thickness measurement method suitable for measuring the thickness of the liquid film in a narrow rectangular channel, including an excitation signal module, an excitation signal preprocessing module, a sensor module, an output Signal processing module, signal acquisition module, data processing module and calibration module, the output end of the excitation signal module is connected to the C1 terminal of the excitation signal preprocessing module, and the C2 terminal of the excitation signal preprocessing module is connected to the C4 terminal of the sensor module , the C5 terminal of the sensor module is connected to the terminal C6 of the output signal processing module, the positive terminal of the signal acquisition module is connected to the output terminal of the C7 terminal of the output signal processing module, and the negative terminal is connected to the GND end of the C7 terminal. The invention has sufficient spatial resolution and can realize the regional measurement of the thickness of the liquid film without invading the liquid film.

Description

technical field [0001] The invention relates to a measuring device and a measuring method in the field of gas-liquid two-phase flow. Background technique [0002] In the modern industrial production process, two-phase fluid flow phenomena are very common, including gas-liquid, gas-solid, liquid-liquid, solid-liquid and other flows. Among them, gas-liquid two-phase flow is a very important topic in the field of nuclear power, especially the detection of gas-liquid two-phase flow parameters is of great significance to the research of heat transfer and hydraulic phenomena. With the miniaturization and miniaturization of reactors, narrow rectangular channels are more and more widely used in plate fuel cores and compact heat exchangers. As an important flow pattern in gas-liquid two-phase flow, annular flow is the basis for the design and stable operation of heat exchange equipment. In safety analysis, it is related to critical heat flux (CHF) such as liquid film evaporation (Dr...

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Problems solved by technology

[0004] Conductivity probes made of printed circuit board technology have good insulation and strong adaptability, and have attracted more and more attention from researchers. For example, the patent "Instantaneous Conductivity Measurement System for Gas-liquid Two-phase Annular Flow Liquid Film Thickness in the Partial Area of ​​the Rod Bundle Channel" ( Application publication date 2019.11.22, application publication number CN 110487163 A, application date 2019.07.04) discloses a measurement system suitable for the annular flow film of the rod bundle channel, which uses the circumferential arrangement of rectangular electrodes made by printed circuit board technology The local circumferential distribution measurement of the liquid film is realized, but its spatial resolution is low and there is no grounding treatment between the pairs of electrodes, which cannot suppress the signal crosstalk. It is not suitable for measuring the distribution of the liquid film thickness in a certain area, and at higher The problem of signal crosstalk is serious under the spatial resolution of 2018. In addition, such as the patent "a device for realizing multi-point real-time measurement of wall liquid film thickness" (application publication date 2018.07.17, application publication number CN 108286934 A, application date 2018.04.09 ) discloses that a printed circuit board made of flexible materials can realize multi-point measurement of liquid film thickness, but it has no grounding treatment, so that the residual electrical signal of the triggered probe is easily accepted by the next probe, resulting in Measurement error, in addition, the slow AC-DC conversion speed will easily lead to inertia and distortion of the output signal, and it can only realize the timing measurement in one direction and cannot realize the measurement of the liquid film thickness in a certain area, and no calibration method is given

[0005] In the above-mentioned published patents, the conductance probe made by printed circuit board technology has depressions between the electrodes that are equivalent to the thickness of the electrodes, and the surface of the board is low in flatness; and its technology uses two-layer board manufacturing technology, so The circuit on the same plane as the electrode reduces the flatness of the board surface, and these two factors increase the measurement error

[0006] The calibration method used in the above published patents is difficult to ensure the absolute parallelism of each component, and this factor also increases the measurement error to a large extent

[0007] In addition, the geometric scale in the narrow rectangular channel is small, and the thickness of the annular flow liquid film changes frequently. Therefore, in the above-mentioned published patents, the spatial resolution, time resolution and sensitivity cannot well meet the measurement requirements, and because the liquid film On the order of microns, the unevenness of the sensor surface brings large measurement errors

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