CN110646044B

CN110646044B - A method and device for non-contact detection of thermal fluid flow

Info

Publication number: CN110646044B
Application number: CN201910985301.7A
Authority: CN
Inventors: 李晋; 杨俊彤; 张华�
Original assignee: Northeastern University China
Current assignee: Northeastern University China
Priority date: 2019-10-16
Filing date: 2019-10-16
Publication date: 2021-03-26
Anticipated expiration: 2039-10-16
Also published as: CN110646044A

Abstract

The invention belongs to the technical field of optical fiber sensing, and in particular relates to a method and a device for non-contact detection of thermal fluid flow. The method includes the following steps: S1, passing the sealed pipe through the heating unit and the energy output unit, and evenly installing a plurality of temperature sensors on the outer wall of the sealed pipe; S2, introducing fluid; S3, obtaining temperature data from each temperature sensor, and using The temperature data is input into a pre-trained neural network model to obtain flow information of the fluid; wherein, the pre-trained neural network model is based on the temperature within a preset historical time period and the corresponding fluid flow information, using a neural network algorithm Run the trained model. The method is based on a preset model, and the temperature of the fluid is measured by a temperature sensor, thereby obtaining the flow information of the fluid in the pipeline.

Description

Method and device for non-contact detection of thermal fluid flow

Technical Field

The invention belongs to the technical field of optical fiber sensing, and particularly relates to a method and a device for non-contact detection of thermal fluid flow.

Background

The control of the operation state of the nuclear power station is very important, great potential safety hazards exist in high-load operation, and the power generation efficiency is rapidly reduced due to low-standard operation. The adjustment of the operation state of the nuclear power station mainly depends on the accurate measurement of the power of a loop, and can be directly obtained through the measurement of the flow of the condensing agent.

However, because the requirement on the sealing performance of a primary circuit is high, a plug-in flowmeter cannot be installed for direct measurement, and the power measurement mode of the primary circuit is mainly obtained by indirectly multiplying the ratio of the measured rotating speed and the rated rotating speed of the primary pump by the rated flow.

In this process, the flow coefficient also needs to be calibrated occasionally using the power calculated by the thermal balance test. The indirect method-based power value measuring process is complex, and the radiation of a loop system is strong, so that the traditional electrical sensor cannot work normally.

Disclosure of Invention

Technical problem to be solved

Aiming at the existing technical problems, the invention provides a method for the non-contact detection of the flow of hot fluid, which is based on a preset model and measures the temperature of the fluid through a temperature sensor so as to obtain the flow information of the fluid in a pipeline.

(II) technical scheme

The invention provides a method for non-contact detection of thermal fluid flow, which comprises the following steps:

s1, enabling the sealed pipeline to penetrate through the heating unit and the energy output unit, and uniformly installing a plurality of temperature sensors on the outer wall of the sealed pipeline;

s2, introducing fluid;

s3, each temperature sensor obtains temperature data, and the temperature data is input into a pre-trained neural network model to obtain flow information of the fluid;

the pre-trained neural network model is a model trained by adopting a neural network algorithm based on the temperature in a preset historical time period and the corresponding flow information of the fluid.

Furthermore, the temperature sensor comprises a micro-nano optical fiber, a single-mode optical fiber and a quartz capillary tube, two ends of the quartz capillary tube are opened, the micro-nano optical fiber and the single-mode optical fiber are fixed on the inner wall of the quartz capillary tube, and a space is reserved between the micro-nano optical fiber and the single-mode optical fiber to form an F-P cavity.

Further, the fluid is a gas, a liquid or a gas-liquid mixed homogeneous fluid.

Further, the temperature sensor is arranged on the outer wall of the sealed pipeline in a polymer embedding and fixing mode.

Further, the heating unit is a nuclear reactor or a flame unit.

The invention also provides a device for the thermal fluid flow non-contact detection method based on the thermal fluid flow non-contact detection device, which comprises a sealed pipeline, a heating unit and an energy output unit, wherein the sealed pipeline penetrates through the heating unit and the energy output unit, a plurality of temperature sensors are uniformly arranged on the outer wall of the sealed pipeline, each temperature sensor consists of a micro-nano optical fiber, a single-mode optical fiber and a quartz capillary, two ends of the quartz capillary are opened, the micro-nano optical fiber and the single-mode optical fiber are fixed on the inner wall of the quartz capillary, and a space is reserved between the micro-nano optical fiber and the single-mode optical fiber to.

Further, the distance between the micro-nano optical fiber and the single-mode optical fiber is 35-45 micrometers.

Further, the diameter of the micro-nano optical fiber is 35-45 micrometers, and the diameter of the single-mode optical fiber is 120-130 micrometers.

(III) advantageous effects

The method for detecting the flow of the hot fluid in a non-contact manner can detect the gradient change trend of the temperature of the outer wall of the pipeline, further obtain the heat conduction distribution characteristic based on the change of the flow of the fluid in the pipeline, obtain the real-time flow of the fluid in the pipeline through calculation and analysis, and realize the non-contact real-time monitoring of the flow of the fluid in the sealed pipeline.

The device for the non-contact detection of the flow of the hot fluid, provided by the invention, has high sensitivity and accurate measurement result.

Drawings

FIG. 1 is a schematic diagram of a temperature gradient curve of a method for non-contact detection of a thermal fluid flow according to the present invention;

FIG. 2 is an apparatus for non-contact detection of thermal fluid flow provided by the present invention;

fig. 3 is a schematic structural diagram of the temperature sensor of the present invention.

[ description of reference ]

1: sealing the pipeline; 2: a heating unit; 3: an energy output unit; 4: a temperature sensor; 41: micro-nano optical fibers; 42: a single mode optical fiber.

Detailed Description

For the purpose of better explaining the present invention and to facilitate understanding, the present invention will be described in detail by way of specific embodiments with reference to the accompanying drawings.

s2, introducing fluid;

Further, the fluid is a gas, a liquid or a gas-liquid mixed homogeneous fluid.

The temperature detected by each temperature sensor changes along with the change of the fluid flow, the method obtains a temperature gradient change curve as shown in figure 1 by detecting the temperature reduction trend of the pipeline in the fluid flow direction, and obtains corresponding fluid flow information by calculating and analyzing the change rate and the trend of the curve.

The invention also provides a device for the above method for non-contact detection of hot fluid flow, as shown in fig. 2, a closed circular ring with an arrow at the center part indicates the flow direction of the fluid, comprising: the sealed pipeline 1, the heating unit 2 and the energy output unit 3, wherein the sealed pipeline 1 penetrates through the heating unit 2 and the energy output unit 3. The sealed pipeline 1 is made of stainless steel or plastic and is of a hollow cylindrical structure, the diameter of the pipeline is larger than 5cm, and the thickness of the pipeline is 15-20cm, so that the installation and detection requirements of the temperature sensor are met. The heating unit 2 is a nuclear reactor or a flame unit (heating by flame heating), and the energy output unit 3 is used for exchanging energy between heat in the pipeline and an external connecting unit.

A plurality of temperature sensors 4 are uniformly installed on the outer wall of the sealed pipe 1, and each temperature sensor 4 detects a different temperature due to a change in the flow rate of the fluid. Preferably, the temperature sensor 4 is mounted on the outer wall of the sealed pipe 1 by means of polymer embedding and fixing. The number of the temperature sensors can be set according to the actual length of the pipeline and detection requirements, and the invention is not limited.

Further, as shown in fig. 3, the temperature sensor 4 is composed of a micro-nano optical fiber 41, a single-mode optical fiber 42 and a quartz capillary, two ends of the quartz capillary are opened, the micro-nano optical fiber 41 and the single-mode optical fiber 42 are fixed on the inner wall of the quartz capillary through a temperature sensitive material PDMS (polydimethylsiloxane), the diameter of the micro-nano optical fiber 41 is 35-45 micrometers, and the diameter of the single-mode optical fiber 42 is 120-130 micrometers. And a distance of 35-45 micrometers is reserved between the first end face of the micro-nano optical fiber 41 and the first end face of the single-mode optical fiber 42, so that an F-P cavity is formed, and the second end face of the micro-nano optical fiber 41 and the second end face of the single-mode optical fiber 42 are respectively flush with or slightly protruded from two ends of the quartz capillary.

The temperature sensor 4 in the invention can excite a high-order mode optical signal by virtue of the micro-nano optical fiber, and simultaneously, the F-P cavity formed between the micro-nano optical fiber and the single-mode optical fiber is utilized for mode selection to generate an interference effect, so that a characteristic spectrum different from the traditional F-P interference is formed. The design of the structure can reduce the demodulation difficulty of the signal light and realize high-precision temperature fluctuation monitoring. The above parameters can be set and made according to the application requirements of the temperature sensing working range and sensitivity.

Principle of detection

When fluid flows in the pipeline, the fluid can exchange heat with the surrounding environment, the heat exchange rate depends on the temperature difference between the fluid in the pipeline and the external environment, and when the fluid flow speed is lower, more heat is lost in the process of flowing through the pipeline with the same length, and the temperature change is larger; for faster fluids, the same length has less heat loss, so the magnitude of fluid flow in a pipe can be estimated based on fixed point observations of temperature on multiple pipes of a particular length.

Before measurement, firstly, learning by utilizing characteristic data of temperatures at different flows to finish calibration work of a sensor system; in actual measurement, the change of the flow in the pipeline can cause the change of a temperature distribution field of the pipeline wall, and the micro fluctuation of the temperature can be detected in real time by installing a high-sensitivity temperature sensor at a specific position of a pipeline system. According to the temperature measurement values of different detection points, a temperature gradient change curve of the pipeline system can be drawn, the neural network algorithm of the temperature gradient change curve is analyzed, curve characteristic information of different flow rates is compared, and finally flow rate information of the fluid is obtained.

The technical principles of the present invention have been described above in connection with specific embodiments, which are intended to explain the principles of the present invention and should not be construed as limiting the scope of the present invention in any way. Based on the explanations herein, those skilled in the art will be able to conceive of other embodiments of the present invention without inventive efforts, which shall fall within the scope of the present invention.

Claims

1. a method for non-contact detection of thermal fluid flow, is characterized in that, comprises the steps:

S1. Pass the sealed pipe through the heating unit and the energy output unit, and evenly install multiple temperature sensors on the outer wall of the sealed pipe;

S2, into the fluid;

S3, each temperature sensor obtains temperature data, and inputs the temperature data into a pre-trained neural network model to obtain the flow information of the fluid;

Wherein, the pre-trained neural network model is a model trained by using a neural network algorithm based on the temperature within a preset historical time period and the flow information of the corresponding fluid;

The temperature detected by each temperature sensor will change with the change of fluid flow. By detecting the temperature decrease trend of the pipeline in the direction of fluid flow, the temperature gradient change curve is obtained. By analyzing the change rate and trend of the curve, the corresponding Fluid flow information.

2. the method for non-contact detection of thermal fluid flow according to claim 1, is characterized in that, described temperature sensor is made up of micro-nano optical fiber, single-mode optical fiber and quartz capillary, and described quartz capillary is open at both ends, The micro-nano optical fiber and the single-mode optical fiber are fixed on the inner wall of the silica capillary, and there is a distance between the micro-nano optical fiber and the single-mode optical fiber to form an F-P cavity.

3 . The method for non-contact detection of thermal fluid flow according to claim 1 , wherein the fluid is a homogeneous fluid of gas, liquid or gas-liquid mixture. 4 .

4 . The method for non-contact detection of thermal fluid flow according to claim 1 , wherein the temperature sensor is installed on the outer wall of the sealed pipe by embedding and fixing the polymer. 5 .

5 . The method for non-contact detection of thermal fluid flow according to claim 1 , wherein the heating unit is a nuclear reactor or a flame unit. 6 .

6. A device for non-contact detection of thermal fluid flow, comprising a sealed pipe (1), a heating unit (2) and an energy output unit (3), the sealed pipe (1) passing through the heating unit (2) and an energy output unit (3), characterized in that a plurality of temperature sensors (4) are uniformly installed on the outer wall of the sealed pipe (1), and the temperature sensors are composed of micro-nano optical fibers (41), single-mode optical fibers (42) and quartz The capillary is formed, the silica capillary is open at both ends, the micro-nano optical fiber (41) and the single-mode optical fiber (42) are fixed on the inner wall of the quartz capillary by PDMS, the micro-nano optical fiber (41) and the single-mode optical fiber (42) There is a gap between them to form an F-P cavity;

The diameter of the micro-nano fiber (41) is 35-45 microns;

The temperature sensor (4) is used to obtain temperature data, and the temperature detected by each temperature sensor will change with the change of the fluid flow. The change rate and trend of the curve can be calculated to obtain the corresponding fluid flow information.

7 . The device for non-contact detection of thermal fluid flow according to claim 6 , wherein the distance between the micro-nano optical fiber and the single-mode optical fiber is 35-45 μm. 8 .

8. The device for non-contact detection of thermal fluid flow according to claim 7, wherein the diameter of the single-mode optical fiber is 120-130 microns.

9 . The device for non-contact detection of thermal fluid flow according to claim 8 , wherein the temperature sensor is installed on the outer wall of the sealed pipe ( 1 ) by embedding and fixing with polymer. 10 .