Testing device and method for coupling flow and heat exchange performance of porous medium

Abstract

The invention discloses a testing device and method for coupling flow and heat exchange performance of a porous medium, and the testing device comprises a medium testing unit which comprises a main body pipe section and a porous medium sample installed on the main body pipe section; the airflow providing unit comprises a nitrogen cylinder and a gas rectifier, the nitrogen cylinder is connected with the main body pipe section through a gas pipe, and the gas rectifier is arranged in the pipeline; the heating unit comprises an electromagnetic induction heater, and a heating coil of the electromagnetic induction heater is wound around the position of the pipeline where the porous medium sample is installed; the measuring unit comprises a front thermocouple, a rear thermocouple, a differential pressure transmitter and an infrared thermal imager and is used for testing the temperatures of the front side and the rear side of the porous medium sample, the pressure difference of the front side and the rear side and temperature rise data; the device not only can be used for measuring the permeability and the inertial resistance coefficient of the porous medium, but also can be used for testing the forced convection heat transfer coefficient of fluid and a solid matrix in the porous medium.

Description

Technical Field

[0001] The present invention relates to the technical field of testing devices, and in particular to a testing device and method for coupling the flow and heat exchange performance of porous media. Background Art

[0002] The study of heat and mass transfer in porous media is a hot topic in the current interdisciplinary development. In related experimental studies of porous media flow, most assume that the physical properties of the fluid are constant, ignoring the influence of the density and dynamic viscosity of the fluid at different flow rates on the fitting of porous media flow characteristic parameters.

[0003] In related porous media heat transfer experimental studies, thermocouples are mostly used to obtain the temperature of the porous medium solid. However, this direct contact temperature measurement method is limited by heat transfer lag and slow temperature measurement response speed. Although some related studies have made temperature corrections, it increases the computational burden during the research process. When calculating the amount of heat applied to the porous medium or fluid, the power of the loading instrument is generally used to subtract all quantifiable heat losses. This indirect method of measuring heating power will lead to certain deviations due to the existence of temperature gradients. Therefore, existing testing devices have certain errors in testing the flow properties and heat transfer performance of porous media. Summary of the Invention

[0004] In response to the problems existing in the prior art, the present invention provides a testing device and method for coupling the flow and heat transfer performance of porous media. It can not only be used to more accurately measure the permeability and inertial resistance coefficient of porous media, but also can be used to more accurately test the forced convection heat transfer coefficient between the fluid inside the porous medium and the solid matrix.

[0005] The technical solutions of the present invention are as follows:

[0006] In a first aspect of the present invention, a testing device for coupling porous medium flow and heat transfer performance is provided, comprising:

[0007] A medium testing unit, comprising a main pipe section and a porous medium sample installed on the main pipe section;

[0008] An airflow providing unit, comprising a nitrogen cylinder and a gas rectifier, wherein the nitrogen cylinder is connected to the main pipe section via a gas pipe, and the gas rectifier is arranged in the pipe;

[0009] A heating unit includes an electromagnetic induction heater, wherein a heating coil of the electromagnetic induction heater is wound around a pipe where the porous medium sample is installed;

[0010] The measuring unit includes a front thermocouple, a rear thermocouple, a differential pressure transmitter and an infrared thermal imager, and is used to test the temperature, pressure difference and temperature rise data of the front and rear sides of the porous medium sample.

[0011] In some embodiments of the present invention, the porous medium sample is fixed on a pipe comprising an inner tube and an outer tube, and both ends of the pipe are mounted on the main pipe section through flanges; the inner tube is provided with two sections, and the porous medium sample is located between the two sections of the inner tube, and an insulation layer is provided at the connection between the porous medium sample and the outer tube for thermal insulation.

[0012] In some embodiments of the present invention, a pressure regulating valve and a thermal gas mass flow meter are provided on the gas pipe.

[0013] In some embodiments of the present invention, the heating coil is made of copper wire sheathed with glass fiber, and an insulation layer is provided between the copper wire and the pipe in which the porous medium sample is installed.

[0014] In some embodiments of the present invention, the front thermocouple and the rear thermocouple are both T-type thermocouples, which are fixed on an iron wire and inserted into a main pipe section with a hole drilled therein, and are sealed with solid glue. The front thermocouple and the rear thermocouple are connected to a temperature collector.

[0015] In some embodiments of the present invention, the infrared thermal imager is fixed at the outlet position of the main pipe section.

[0016] In a second aspect of the present invention, a method for testing the flow properties of a porous medium is provided, comprising the following steps:

[0017] Open the nitrogen bottle and adjust the volume flow of nitrogen to the set volume flow;

[0018] After the pressure difference between the front and rear sides of the porous medium sample stabilizes, record the pressure difference data and the data of the front thermocouple;

[0019] Calculate the average pressure based on the pressure difference data and the local atmospheric pressure, and query the density and dynamic viscosity of the fluid in this state based on the average pressure and the front thermocouple data;

[0020] By changing the volume flow rate multiple times, multiple sets of data are obtained;

[0021] The porous media flow model formula is used to fit a variety of data to obtain the flow performance parameters of the porous media samples.

[0022] In some embodiments of the present invention, the porous media flow model formula is:

[0023]

[0024] Where Δp represents the pressure data obtained by the differential pressure transmitter; v represents the fluid flow rate; ρ represents the fluid density; μ represents the dynamic viscosity; L represents the thickness of the porous medium sample; K represents the sample permeability; and R represents the sample inertial resistance coefficient.

[0025] In a third aspect of the present invention, a method for testing the heat transfer performance of a porous medium is provided, comprising:

[0026] Turn on the electromagnetic induction heater and introduce nitrogen at a set flow rate;

[0027] When the temperature of the porous medium sample no longer changes, record the average temperature, front side temperature, and back side temperature at this time, and calculate the temperature difference between the solid matrix of the porous medium sample and the internal fluid;

[0028] According to the formula q=hAΔT g-f The forced convection heat transfer coefficient inside the porous medium sample is calculated; where q represents the calibrated heating power; A represents the total heat transfer area inside the porous medium sample; ΔT g-f represents the temperature difference between the solid matrix and the internal fluid of the porous medium sample; h represents the forced convection heat transfer coefficient inside the porous medium sample.

[0029] In some embodiments of the present invention, the temperature difference ΔT between the solid matrix of the porous medium sample and the internal fluid is g-f Calculated by the following formula:

[0030]

[0031] Among them, T w represents the average temperature of the porous medium sample, T in represents the front side temperature of the porous medium sample, T out represents the backside temperature of the porous media sample.

[0032] One or more technical solutions of the present invention have the following beneficial effects:

[0033] (1) The test device for coupling the flow and heat transfer performance of porous media provided by the present invention can not only be used to measure the permeability and inertial resistance coefficient of porous media, but also can be used to test the forced convection heat transfer coefficient between the fluid inside the porous media and the solid matrix.

[0034] (2) The porous medium flow performance testing method provided by the present invention fully considers the influence of the density and dynamic viscosity of the fluid working medium on the internal flow characteristic parameters of the porous medium under different flow conditions, thereby obtaining flow characteristic parameters that are closer to the actual situation.

[0035] (3) The present invention reduces the problems of heat dissipation and transfer delay in traditional contact temperature measurement by introducing a non-contact temperature measurement module to measure the temperature of the porous medium; by connecting a passive heating module instead of traditional contact heating, uniform heating of the porous medium and accurate calculation of the heated value can be achieved.

[0036] (4) The testing method of the present invention can eliminate the testing errors caused by the temperature gradient during contact temperature measurement and heating, and effectively improve the testing accuracy of the flow and heat transfer performance parameters of porous media.

[0037] (5) The present invention can realize the flow and heat transfer performance test of porous media with a wide flow rate and multiple types. On this basis, the flow and heat transfer characteristic correlation formula of the relevant porous media can be fitted, and the flow and heat transfer performance of a certain porous medium can be predicted within a specific range without experimental testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of the structure of the testing device for coupling porous medium flow and heat transfer performance of the present invention;

[0039] Figure 2 for Figure 1 A partial enlarged schematic diagram of point A in the middle;

[0040] Figure 3 This is a comparison chart between the sample flow experimental data and the model calculation results;

[0041] Figure 4 This is a comparison chart of the sample heat transfer experimental data and simulation calculation results.

[0042] In the figure: 1. Nitrogen cylinder; 2. Pressure regulating valve; 3. Thermal gas mass flow meter; 4. Gas rectifier; 5. Pre-thermocouple; 6. Temperature acquisition instrument; 7. Differential pressure transmitter; 8. Electromagnetic induction heater; 9. Infrared thermal imager; 10. Main pipe section; 11. Outer pipe; 12. Inner pipe; 13. Ceramic fiber insulation layer; 14. Porous medium sample; 15. Post-thermocouple; 16. Insulation layer; 17. Heating coil. DETAILED DESCRIPTION

[0043] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0044] Example 1

[0045] In a typical embodiment of the present invention, a test device for coupling porous medium flow and heat transfer performance is proposed, such as Figure 1 and Figure 2 Shown, including:

[0046] The medium testing unit includes a main pipe section 10 and a porous medium sample 14 installed on the main pipe section 10;

[0047] The air flow providing unit includes a nitrogen cylinder 1 and a gas rectifier 4. The nitrogen cylinder 1 is connected to the main pipe section 10 through an air pipe, and the gas rectifier 4 is arranged in the pipe;

[0048] A heating unit, comprising an electromagnetic induction heater 8, wherein a heating coil 17 of the electromagnetic induction heater 8 is wound around a pipe where the porous medium sample 14 is installed;

[0049] The measuring unit includes a front thermocouple 5, a rear thermocouple 15, a differential pressure transmitter 7 and an infrared thermal imager 9, and is used to measure the temperature, pressure difference and temperature rise data of the front and rear sides of the porous medium sample 14.

[0050] Among them, the airflow providing unit has a rectification function, which is used to provide the entire device with a fluid working medium with a uniform flow rate in the pipeline cross section; the medium testing unit has passive heating and radial insulation functions, which is used to install the heating unit and porous medium samples.

[0051] In this embodiment, the porous medium sample 14 is fixed on a pipe containing an inner tube 12 and an outer tube 11, and both ends of the pipe are installed on the main pipe section 10 through flanges; the inner tube 12 is provided with two sections, and the porous medium sample 14 is located between the two sections of the inner tube 12, and a ceramic fiber insulation layer 13 is provided at the connection between the porous medium sample 14 and the outer tube for thermal insulation.

[0052] Furthermore, a rubber pad is attached to the flange, and on the pipe that fixes the porous medium sample, two sections of inner tubes 12 with the same inner and outer diameters are in close contact with the outer tube 11. The section of inner tube 12 close to the incoming flow direction is fixed to the inside of the outer tube 11 by liquid glue, and the other section of inner tube remains detachable to facilitate the replacement of the porous medium. A ceramic fiber insulation layer 13 with the same inner and outer diameters is filled in between the two sections of the inner tube. Its thickness is slightly larger than that of the porous medium sample 14, which can isolate the heat of the porous material from being conducted to the pipe, avoiding affecting the test accuracy of the porous medium heat transfer coefficient. In order to ensure the fixing effect of the insulation layer on the position of the porous medium, hard insulation materials should generally be used. There is a boss inside the ceramic fiber insulation layer 13, and the inner diameter of this boss decreases along the direction of fluid flow to ensure that the porous material will not deflect or displace under different flow tests.

[0053] In this embodiment, the gas pipe is provided with a pressure regulating valve 2 and a thermal gas mass flowmeter 3. The pressure regulating valve 2 controls the outlet pressure of the nitrogen cylinder 1. The thermal gas mass flowmeter 3 is connected to a controller, and the thermal gas mass flowmeter 3 and the controller control and display the internal fluid flow in real time. The flowmeter outlet pipe is reduced in diameter to the main pipe section 10, and a gas rectifier 4 is used to achieve uniform flow of the internal fluid, reducing the impact of the jet on the porous medium flow and heat transfer performance test.

[0054] In this embodiment, the heating coil 17 is made of copper wire sheathed in glass fiber. The copper wire is evenly wound around the outer tube 11 of the dielectric testing unit. An insulation layer 16 is placed between the copper wire and the pipe containing the porous dielectric sample 14 to prevent the copper wire from overheating and melting the pipe. Because electromagnetic induction heating is used, the presence of insulation material inside and outside the pipe does not affect heating performance. All pipes should be made of non-metallic materials; in this device, acrylic is used.

[0055] In some other implementations of this embodiment, electromagnetic induction heating may also be replaced by hot air heating, microwave heating, infrared heating, radio frequency heating, laser heating, etc. Before testing the heat transfer coefficient of the porous medium, the passive heating module should be calibrated and calculated to calculate the heating power of the porous medium.

[0056] In this embodiment, the front thermocouple 5 and the rear thermocouple 15 are both T-type thermocouples, which are fixed on an iron wire and inserted into a main pipe section 10 with a hole drilled therein, and are sealed with solid glue. The front thermocouple and the rear thermocouple are connected to a temperature collector 6. During the specific installation, the front thermocouple 5 for measuring the fluid inlet temperature is fixed on a thin iron wire and inserted into a main pipe section 10 with a hole drilled therein. In order to prevent gas leakage, a solid glue is used to seal it. The rear thermocouple 15 for measuring the fluid temperature at the outlet of the porous medium has three temperature measuring points evenly fixed on the thin iron wire. The thin iron wire passes through a self-made fastening head and is fixed so that the temperature measuring points can collect the temperature distribution in the radial direction of the porous material. The fastening head can be stuck on the main pipe to facilitate the insertion and removal of the thermocouple in subsequent operations. The collected thermocouple data is recorded by the temperature collector 6.

[0057] In some other implementations of this embodiment, the front thermocouple 5 and the rear thermocouple 15 may also be formed by other contact temperature measuring instruments such as thermocouple temperature measurement, thermistor temperature measurement, platinum resistance temperature measurement, bimetallic thermometer, electronic temperature sensor, etc.

[0058] In this embodiment, the infrared thermal imager 9 is fixed at the outlet position of the main pipe section 10 to collect the temperature of the porous medium in real time, and the differential pressure transmitter 7 is connected to both sides of the medium testing unit to collect the pressure difference between the two ends of the porous medium sample in real time.

[0059] In some other implementations of this embodiment, the infrared thermal imager 9 may also be replaced by a non-contact temperature measuring instrument such as an infrared thermometer, a laser thermometer, an optical pyrometer and a brightness pyrometer, a radiation thermometer, a colorimetric thermometer, a sonic temperature sensor, or an ultrasonic thermometer;

[0060] The method for using the testing device for coupling porous medium flow and heat transfer performance provided in this embodiment is as follows:

[0061] In the flow performance test of porous media:

[0062] (1) Fix the porous medium to be measured, and the flowmeter controller controls the pipeline flow at a certain value. After the pressure difference at both ends of the porous medium stabilizes, record the pressure value and the transient temperature value of the fluid working medium at this time; the thickness of the porous medium to be measured should be as thin as possible so that the average temperature of one end surface can replace the average temperature of the entire porous medium.

[0063] (2) Changing the flow rate of the controller and averaging the pressure and temperature values ​​of the fluid at different flow rates, the permeability and inertial resistance coefficient inside the porous medium are fitted within the control flow range of the flowmeter controller using the Darcy-Forchheimer flow model;

[0064] In the heat transfer performance test of porous media:

[0065] (1) Fix the porous medium to be measured, turn on the non-contact temperature measurement module, and after the temperature measurement module reaches thermal equilibrium with the surrounding environment, start the temperature real-time recording function of the non-contact temperature measurement module, and at the same time turn on the passive heating module to heat the porous medium; after the temperature of the porous medium rises significantly, stop heating and stop temperature acquisition by the non-contact temperature measurement module;

[0066] (2) The measured temperature of the porous medium is fitted with the scatter points of the change with the heating time. According to the first law of thermodynamics, the power of the passive heating module for heating the porous medium can be obtained;

[0067] (3) Adjust the value of the flowmeter controller and start the non-contact temperature measurement and passive heating modules at a certain flow rate. After the transient temperature value reaches stability, the amount of heat applied to the porous medium is equal to the forced convection heat transfer between the fluid and the solid matrix inside the porous medium.

[0068] (4) inserting a contact temperature measurement module at the airflow outlet side of the porous medium and collecting the temperature of the fluid entering and leaving the porous medium in real time;

[0069] (5) By changing the pipeline flow rate, the corresponding forced convection heat transfer coefficient inside the porous medium under various flow rates can be calculated.

[0070] Example 2

[0071] In a typical embodiment of the present invention, a method for testing the flow properties of a porous medium is provided, comprising the following steps:

[0072] Open the nitrogen bottle and adjust the volume flow of nitrogen to the set volume flow;

[0073] After the front and rear sides of the porous medium sample are stable, record the pressure difference data and the data of the front thermocouple;

[0074] Calculate the average pressure based on the pressure difference data and the local atmospheric pressure, and query the density and dynamic viscosity of the fluid in this state based on the average pressure and the front thermocouple data;

[0075] By changing the volume flow rate multiple times, multiple sets of data are obtained;

[0076] The porous media flow model formula is used to fit a variety of data to obtain the flow performance parameters of the porous media samples.

[0077] Furthermore, the porous media flow model formula is:

[0078]

[0079] Where Δp represents the pressure data obtained by the differential pressure transmitter; v represents the fluid flow rate; ρ represents the fluid density; μ represents the dynamic viscosity; L represents the thickness of the porous medium sample; K represents the sample permeability; and R represents the sample inertial resistance coefficient.

[0080] Taking two porous media test samples 14 as an example, one is a sintered stainless steel wire mesh with a thickness of 1.7 mm and the other is a sintered stainless steel powder with a thickness of 2 mm. The test methods for the two are the same, as follows:

[0081] Sample flow performance test

[0082] (1) Install and secure the test sample, open the valve of the nitrogen bottle 1, pressurize the pressure regulating valve 2 to 0.7 MPa, turn on the thermal gas mass flow meter 3 and its controller, and start formal operation after the flow meter reaches thermal equilibrium.

[0083] (2) Adjust the controller knob to control the volume flow rate to Q. After the pressure difference stabilizes, record the data of the differential pressure transmitter 7 and the front thermocouple 5 at this time, which are recorded as Δp and T respectively. g .

[0084] (3) According to the law of conservation of mass, it is assumed that the temperature of the fluid remains unchanged during the flow process. Inside the main pipe section, the apparent flow velocity of the fluid is Where d is the inner diameter of the main pipe section.

[0085] (4) The average pressure of the sample can be calculated from Δp and the local atmospheric pressure p0

[0086] (5) According to the average pressure p at the sample and the pre-temperature T g , the density ρ and dynamic viscosity μ corresponding to the fluid in this state can be derived in the REFPROP software.

[0087] (6) By adjusting the controller knob, change the different flow rates inside the system and record the pressure difference and temperature at this flow rate.

[0088] (7) According to the Darcy-Forchheimer formula of porous media flow model The flow performance parameters of the sample, namely the sample permeability and the sample inertial resistance coefficient, are fitted. Where L is the thickness of the sample, K is the sample permeability, and R is the sample inertial resistance coefficient.

[0089] When the apparent velocity is 0.27-3.32m / s, the permeability of the 1.7mm 150 mesh sintered stainless steel wire mesh sample is 1.40e -10 m 2 , the average inertial resistance coefficient is 37587.57m -1 The permeability of 500 mesh sintered stainless steel powder with a thickness of 2 mm is 9.31e -12 m 2 The average inertial resistance coefficient is 128129.51m -1 .

[0090] The reliability of the flow experiment design scheme was verified by taking sintered stainless steel wire mesh 150 mesh as an example. The sample permeability and inertial resistance coefficient obtained from the experiment were substituted into the commercial CFD software for relevant simulation research. The pressure drop of the simulated sample was compared with the experimental value. The results are shown in Figure 3 In the apparent velocity range of 0.27 to 3.32 m / s, the maximum relative error between the experiment and the simulation is 6.95%, and the average relative error is 1.88%, which meets the requirements of engineering calculations and verifies the reliability of the flow experiment.

[0091] Example 3

[0092] In a typical embodiment of the present invention, a method for testing the heat transfer performance of a porous medium includes:

[0093] Turn on the electromagnetic induction heater and introduce nitrogen at a set flow rate;

[0094] When the temperature of the porous medium sample no longer changes, record the average temperature, front side temperature, and back side temperature at this time, and calculate the temperature difference between the solid matrix of the porous medium sample and the internal fluid;

[0095] According to the formula q=hAΔT g-f The forced convection heat transfer coefficient inside the porous medium sample is calculated; where q represents the calibrated heating power; A represents the total heat transfer area inside the porous medium sample; ΔT g-f represents the temperature difference between the solid matrix and the internal fluid of the porous medium sample; h represents the forced convection heat transfer coefficient inside the porous medium sample.

[0096] Furthermore, the temperature difference ΔT between the solid matrix of the porous medium sample and the internal fluid is g-fCalculated by the following formula:

[0097]

[0098] Among them, T w represents the average temperature of the porous medium sample, T in represents the front side temperature of the porous medium sample, T out represents the backside temperature of the porous media sample.

[0099] Taking two porous media test samples 14 as an example, one is a sintered stainless steel wire mesh with a thickness of 1.7 mm and the other is a sintered stainless steel powder with a thickness of 2 mm. The test methods for the two are the same, as follows:

[0100] In the sample heat transfer performance test, the radiation heat transfer of the heated porous medium test sample and the heat conduction between the sample and the pipeline in the radial direction are ignored.

[0101] (1) Turn on the infrared thermal imager 9 and allow it to reach thermal equilibrium with the surrounding environment before use.

[0102] (2) Before formally testing the heat transfer performance of the sample, the heating power q of the sample by the electromagnetic induction heating device should be calibrated. The specific operation is:

[0103] a. Average temperature of the sample surface during video recording;

[0104] b. Turn on the electromagnetic induction heating device. When the temperature displayed by the thermal imager rises significantly, stop heating and end recording to obtain the sample temperature T. g-g Curves that vary with heating time t;

[0105] c. According to the first law of thermodynamics, the amount of heat added to the sample is equal to the increase in its internal energy, q·t=c p mΔT g-g Heating, where c p is the constant pressure specific heat capacity of the sample, m is the weight of the sample;

[0106] d. Convert the above formula into a fitting curve form, The independent variable is the heating time t, and the dependent variable is the sample temperature ΔT g-g The slope is the quotient of the sample heating power and the product of the sample's constant pressure specific heat and its mass. This completes the calibration of the sample heating power.

[0107] (3) Turn on the infrared thermal imager 9 to record the sample temperature rise data, turn on the electromagnetic induction heating module 8 to heat the sample, and control the flow rate of nitrogen to flow into the system.

[0108] (4) When the sample temperature no longer changes and reaches thermal equilibrium, the average temperature of the sample at this time is recorded as T w, insert the rear T-type thermocouple 15 into the rear side of the sample, record the temperature values ​​of the front and rear thermocouples, and record them as T in and T out .

[0109] (5) At this time, the amount of heat applied to the sample is equal to the forced convection of nitrogen inside the sample and the solid matrix, that is, q = hAΔT g-f , where h is the forced convection heat transfer coefficient inside the sample, which is used to characterize the heat transfer performance of the sample; A is the total heat transfer area inside the porous medium sample, which can be determined according to the specific surface area detection method; ΔT g-f is the temperature difference between the sample solid matrix and the internal fluid, which can be obtained according to the logarithmic mean method, that is,

[0110] (6) Pull out the rear thermocouple, change the gas flow rate in the system, and repeat the above operation to achieve the corresponding forced convection heat transfer coefficient of the porous medium sample at different flow rates.

[0111] When the apparent velocity is 1.33m / s, the forced convection heat transfer coefficient of the 1.7mm 150 mesh sintered stainless steel wire mesh sample is 24.09W / (m 2 K), the forced convection heat transfer coefficient of 2mm thick 500 mesh sintered stainless steel powder is 12.67W / (m 2 ·K).

[0112] The reliability of the heat transfer experiment design scheme was verified by taking sintered stainless steel wire mesh 150 mesh as an example. The sample heating power and forced convection heat transfer coefficient obtained from the experiment were substituted into the commercial CFD software for relevant simulation research. After the sample heat transfer stabilized, the temperature was kept constant. The sample temperature obtained by simulation was compared with the experimental value. The results are shown in Figure 4 In the apparent velocity range of 0.40 to 2.79 m / s, the maximum relative error between the two is 8.51%, and the average relative error between the two is 5.17%, which meets the requirements of engineering calculations and verifies the reliability of the flow experiment.

[0113] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without any creative work are still within the scope of protection of the present invention.

Claims

1. A testing device for coupling porous medium flow and heat transfer performance, characterized in that: include: A medium testing unit, comprising a main pipe section and a porous medium sample installed on the main pipe section; An airflow providing unit, comprising a nitrogen bottle and a gas rectifier, wherein the nitrogen bottle is connected to the main pipe section through a gas pipe, and the gas rectifier is arranged in the pipeline; A heating unit, comprising an electromagnetic induction heater, wherein a heating coil of the electromagnetic induction heater is wound around a pipe where the porous medium sample is installed; The measuring unit, including a front thermocouple, a rear thermocouple, a differential pressure transmitter and an infrared thermal imager, is used to test the temperature of the front and rear sides of the porous medium sample, the pressure difference between the front and rear sides and the temperature rise data.

2. The testing device for coupling porous medium flow and heat transfer performance according to claim 1, characterized in that: The porous medium sample is fixed on a pipeline comprising an inner tube and an outer tube, and both ends of the pipeline are installed on the main pipe section through flanges; the inner tube is provided with two sections, and the porous medium sample is located between the two sections of the inner tube, and an insulation layer is provided at the connection between the porous medium sample and the outer tube for heat insulation.

3. The testing device for coupling porous medium flow and heat transfer performance according to claim 1, characterized in that: The gas pipe is provided with a pressure regulating valve and a thermal gas mass flow meter.

4. The testing device for coupling porous medium flow and heat transfer performance according to claim 1, characterized in that: The heating coil is made of copper wire sheathed with glass fiber, and a heat-insulating layer is arranged between the copper wire and the pipeline on which the porous medium sample is installed.

5. The testing device for coupling porous medium flow and heat transfer performance according to claim 1, characterized in that: The front thermocouple and the rear thermocouple are both T-type thermocouples, which are fixed on the iron wire and inserted into the main pipe section with a hole drilled therein and sealed with solid glue. The front thermocouple and the rear thermocouple are connected to a temperature collector.

6. The testing device for coupling porous medium flow and heat transfer performance according to claim 1, characterized in that: The infrared thermal imager is fixed at the outlet position of the main pipe section.

7. A method for testing the flow properties of porous media, implemented using the testing device according to any one of claims 1 to 6, characterized in that: The following steps are involved: Open the nitrogen bottle and adjust the volume flow rate of nitrogen to the set volume flow rate; After the pressure difference between the front and rear sides of the porous medium sample is stable, the pressure difference data and the data of the front thermocouple are recorded; Calculate the average pressure based on the pressure difference data and the local atmospheric pressure, and query the density and dynamic viscosity of the fluid in this state based on the average pressure and the front thermocouple data; By changing the volume flow rate multiple times, multiple sets of data are obtained; The porous media flow model formula is used to fit various data to obtain the flow performance parameters of the porous media samples.

8. The porous medium flow performance testing method according to claim 7, characterized in that: The porous media flow model formula is: Wherein, Δp represents the pressure data obtained by the differential pressure transmitter; v represents the fluid flow rate; ρ represents the fluid density; μ represents the dynamic viscosity; L represents the thickness of the porous medium sample; K represents the sample permeability, and R represents the sample inertial resistance coefficient.

9. A method for testing the heat transfer performance of a porous medium, implemented by using the testing device according to any one of claims 1 to 6, characterized in that: include: Turn on the electromagnetic induction heater and introduce nitrogen at a set flow rate; When the temperature of the porous medium sample no longer changes, the average temperature, the front temperature, and the rear temperature are recorded, and the temperature difference between the solid matrix and the internal fluid of the porous medium sample is calculated; According to the formula q = hAΔT g-f The forced convection heat transfer coefficient inside the porous medium sample is calculated; where q represents the calibrated heating power; A represents the total heat transfer area inside the porous medium sample; ΔT g-f represents the temperature difference between the solid matrix and the internal fluid of the porous medium sample; h represents the forced convection heat transfer coefficient inside the porous medium sample.

10. The porous medium heat exchange performance testing method according to claim 9, characterized in that: Temperature difference ΔT between the solid matrix and the internal fluid of the porous medium sample g-f Calculated by the following formula: Among them, T w represents the average temperature of the porous medium sample, T in represents the front side temperature of the porous medium sample, T out Represents the backside temperature of the porous media sample.

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