A plug-and-play probe-based thermal testing method for thermal storage materials

Abstract

This invention discloses a plug-and-play probe-based thermal testing method and system for thermal storage materials. The system includes a temperature data acquisition instrument, a programmable linear DC power supply, a control device, a high-low temperature alternating humidity chamber, and a probe, wherein the probe is an integrated heating and detection probe. The probe is communicatively connected to the temperature data acquisition instrument, and the temperature data acquisition instrument, the programmable linear DC power supply, and the high-low temperature alternating humidity chamber are all communicatively connected to the control device. The programmable linear DC power supply is electrically connected to the probe. This invention increases the diameter of the integrated heating and detection probe to 3-6 mm, and then corrects and fits the detection results. This method reduces the requirements for the sample being tested and also increases the toughness of the detector, achieving plug-and-play functionality.

Description

Technical Field

[0001] This invention relates to the field of thermal testing technology. Specifically, it relates to a plug-and-play probe-based thermal testing method for heat storage materials. Background Technology

[0002] Thermal conductivity and thermal diffusivity are measures of a material's ability and rate of heat conduction, respectively, and are fundamental physical properties of matter. By measuring thermal conductivity and thermal diffusivity, the volumetric specific heat of a material can be calculated. Industrial construction, materials research and development, and chip heat dissipation are all inextricably linked to the thermophysical properties of heat storage materials, such as thermal conductivity, volumetric specific heat, and thermal diffusivity. Parameters like thermal conductivity are not only the basis for evaluating the thermal conductivity performance of materials but also the basis for material selection in industrial application design. Thermal conductivity measurement equipment plays a crucial role in measuring the thermal conductivity of materials. Based on the heat conduction mechanism, thermal conductivity experimental measurement methods are mainly divided into two types according to the measured state: steady-state methods and unsteady-state methods. Steady-state methods are methods where the measurement state is stable before measurement; that is, after the temperature of the sample reaches a stable state, its thermal conductivity can be calculated by measuring the temperature distribution and heat flow rate of the sample. Unsteady-state methods involve measuring the sample during the measurement process, where the temperature changes continuously over time. Its basic principle is the unsteady-state heat conduction differential equation, and it has the advantages of high speed and high accuracy. Currently, equipment for measuring thermal conductivity using the transient method has certain requirements regarding the size, shape, and other specifications of the sample to be tested, which imposes certain limitations on sample preparation and the selection of the measurement environment. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is to provide a plug-and-play probe-type thermal testing method and system for thermal storage materials based on the unsteady-state method. The diameter of the integrated heating and detection probe is increased to 3-6 mm, and then the detection results are corrected and fitted. This method reduces the requirements for the sample to be tested, while also increasing the toughness of the detector, thus achieving the purpose of plug-and-play.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0005] A plug-and-test probe-based thermal testing method for thermal storage materials includes the following steps:

[0006] S1) Select a probe of appropriate specifications according to the size of the material sample to be tested, and make a sample hole on the material sample to be tested. The diameter of the sample hole is the same as the diameter of the selected probe, and the depth of the sample hole is greater than or equal to the length of the selected probe. The diameter of the selected probe is 3 to 6 mm.

[0007] S2) Apply thermal grease evenly around the selected probe, and then insert the selected probe into the sample hole punched in step S1).

[0008] S3) Simultaneously turn on the probe power supply via the control terminal to activate the temperature data acquisition instrument and measure the temperature of the selected probe.

[0009] S4) After the measured temperature range stabilizes, the programmable linear current source is turned on to heat the selected probe. The K-type thermocouple in the selected probe transmits the collected probe temperature signal to the temperature data acquisition instrument, which then feeds it back to the control terminal. After measuring for 100-150 seconds, a T-lnt curve is obtained, and the measured thermal conductivity is calculated based on the curve.

[0010] S5) The actual thermal conductivity can be obtained by correcting the measured thermal conductivity with the correction factor γ.

[0011] The correction coefficient γ in step S5) of the above-mentioned plug-and-test probe-type thermal storage material thermal testing method is calculated by the following formula:

[0012]

[0013] In the formula, δ is the ratio of the length to the diameter of the selected probe.

[0014] The above-mentioned plug-and-test probe-type thermal testing method for thermal storage materials, the formula for calculating the correction coefficient γ in step S5) is obtained through the following steps:

[0015] ss1) Using the Fluent simulation method, a large number of simulation calculations were performed on the use of probes of different sizes, and the calculated thermal conductivity was divided by the preset thermal conductivity to obtain a series of coefficients φ related to the probe size;

[0016] ss2) Fit the coefficient φ obtained in step ss1) using Origin to obtain a coefficient formula that is only related to the probe aspect ratio. This coefficient formula is the formula for calculating the correction coefficient γ.

[0017] The system for thermal testing using the above-mentioned plug-and-test probe-type thermal storage material thermal testing method includes a temperature data acquisition instrument, a programmable linear DC power supply, a control device, a high and low temperature alternating humidity chamber, and a probe, wherein the probe is an integrated heating and detection probe; the probe is communicatively connected to the temperature data acquisition instrument, the temperature data acquisition instrument, the programmable linear DC power supply, and the high and low temperature alternating humidity chamber are respectively communicatively connected to the control device, and the programmable linear DC power supply is electrically connected to the probe.

[0018] In the above system, the probe includes a probe top and a probe tail, with the lower end of the probe top connected to the top end of the probe tail; the probe tail includes a tube body, a heating wire, and a thermocouple, with the heating wire and the thermocouple respectively disposed within the tube body, the heating point of the heating wire being in close contact with the temperature measuring point of the thermocouple and fixed to the bottom inner side of the tube body; the diameter of the tube body is 3-6 mm.

[0019] In the above system, multiple heating wires are arranged axially around the thermocouple.

[0020] In the above system, the multiple heating wires and thermocouples are arranged at equal intervals along the axis.

[0021] In the above system, the top of the probe has an I-shaped handle, and the vertical part of the I-shaped handle has a through hole. The I-shaped handle is made of 304 stainless steel. The upper end of the heating wire and the upper end of the thermocouple are connected to the wire through the through hole.

[0022] In the above system, a heat insulation pad is provided between the I-shaped handle and the upper end of the tube body, and the heat insulation pad is a gasket made of aluminum silicate fiber.

[0023] In the above system, the tube body is filled with thermally conductive silicone grease.

[0024] The technical solution of the present invention achieves the following beneficial technical effects:

[0025] The thermal testing method involved in this invention is a transient method, belonging to the category of unsteady-state methods. Its basic principle is the unsteady-state heat conduction differential equation, which has the advantages of high speed and accuracy. Combining the single-valuedness condition, the unsteady-state heat conduction differential equation is derived and simplified to obtain the relationship ΔT=f(λ,α). By linearly fitting the relatively linear part of the experimentally obtained ΔT-lnt curve, and further substituting into the equation, the thermal conductivity and thermal diffusivity of the sample under test can be obtained. Furthermore, the specific heat can be calculated based on these two parameters. By adjusting the probe diameter, the requirements for the sample under test in the unsteady-state method are reduced, reducing or eliminating the limitations imposed by existing unsteady-state methods on sample preparation and measurement environment selection. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the working principle of the thermal testing system in this invention.

[0027] Figure 2 This is a schematic diagram of the probe structure in this invention;

[0028] Figure 3 This is a schematic diagram of the plug-and-test probe-type thermal testing method for thermal storage materials in this invention.

[0029] The attached diagram is labeled as follows: 4-1-Heating wire, 4-2-Thermocouple, 4-3-Tube body, 4-4-I-shaped handle, 4-5-Insulation pad, 4-6-Through hole, 4-7-Bolt. Detailed Implementation

[0030] like Figure 1 As shown, a system for thermal testing using a plug-and-play probe-type thermal storage material thermal testing method includes a temperature data acquisition instrument 2, a programmable linear DC power supply 3, a control device 1, a high and low temperature alternating humidity chamber, and a probe 4. The probe 4 is an integrated heating and detection probe. The probe 4 is communicatively connected to the temperature data acquisition instrument 2. The temperature data acquisition instrument 2, the programmable linear DC power supply 3, and the high and low temperature alternating humidity chamber are all communicatively connected to the control device 1. The programmable linear DC power supply 2 is electrically connected to the probe 4.

[0031] The control device 1 is used to control the start and stop of the entire system and to process and display data. The temperature data acquisition instrument 2 is used to receive, convert, and transmit the temperature signal measured by the probe 4. The programmable linear current source 3 is used to provide heating power for the probe 4, and the output current is used to heat the probe 4 through the heating wire 4-1. This device can also be remotely controlled and has programmable functions. The probe 4 is used to measure the sample to be tested and is the connection point between the device and the sample to be tested. As the temperature of the probe 4 increases, it will transfer heat to the sample to be tested. This process is reflected in the temperature rise of the probe 4 itself. The K-type thermocouple is used to connect the probe 4 to the temperature data acquisition instrument 2 to measure the temperature of the probe 4. The heating wire 4-1 is used to heat the probe 4. When current passes through the heating wire 4-1, the heating wire 4-1 generates heat to heat the probe 4. The high and low temperature alternating humidity chamber is used to provide a controllable external environment for the measurement process, simulate the actual outdoor temperature and humidity environment, and provide the required external conditions for the measurement system.

[0032] The probe 1 includes a probe top and a probe tail, with the lower end of the probe top connected to the top end of the probe tail. The probe tail includes a tube 4-3, a heating wire 4-1, and a thermocouple 4-2. The heating wire 4-1 and the thermocouple 4-2 are respectively disposed inside the tube 4-3. The heating point of the heating wire 4-1 is in close contact with the temperature measuring point of the thermocouple 4-2 and is fixed to the bottom inner side of the tube 4-3. The diameter of the tube 4-3 is 3-6 mm. The two heating wires 4-1 and the thermocouple are axially spaced equally, and the tube 4-3 is filled with thermally conductive silicone grease.

[0033] The probe has an I-shaped handle 4-4 at the top, and the vertical part of the I-shaped handle 4-4 has a through hole 4-6. The I-shaped handle 4-4 is made of 304 stainless steel. The upper end of the heating wire 4-1 and the upper end of the thermocouple 4-2 are connected to the wire through the through hole 4-6. The heating wire 4-1 is electrically connected to the programmable linear DC power supply 3 through the wire, and the thermocouple 4-2 is communicatively connected to the temperature data acquisition instrument 2 through the wire.

[0034] A heat insulation pad 4-5 is provided between the I-shaped handle 4-4 and the upper end of the tube body 4-3. The heat insulation pad 4-5 is a gasket made of aluminum silicate fiber.

[0035] In this embodiment, the temperature data acquisition instrument 2 has at least two acquisition channels, which can be paired with K-type thermocouples, and the acquisition frequency meets the requirement of 8 times / s; the programmable linear current source 3 has a channel output of 6V / 6A. The probes 4 have the following specifications: a 3mm diameter probe corresponds to two lengths, 30mm and 60mm; a 5mm diameter probe corresponds to two lengths, 30mm and 60mm; and a 6mm diameter probe corresponds to three lengths, 30mm, 60mm, and 90mm. The tube body 4-3 of the probe 4 has a seamless 321 stainless steel surface and is filled with magnesium oxide. The heating wire 4-1 uses 2080 nickel-chromium wire, and the thermocouple 4-2 is a K-type thermocouple. The high and low temperature alternating humidity chamber has a temperature range of -40 to 150℃ and is mainly designed for the actual working conditions of heat storage materials in the construction industry.

[0036] The steps for conducting thermal testing on the heat storage material using the system are as follows:

[0037] S1) Select a probe of appropriate specifications according to the size of the material sample to be tested, and make a sample hole on the material sample to be tested. The diameter of the sample hole is the same as the diameter of the selected probe, and the depth of the sample hole is greater than or equal to the length of the selected probe. The diameter of the selected probe is 3 to 6 mm.

[0038] S2) Apply thermal grease evenly around the selected probe, and then insert the selected probe into the sample hole punched in step S1).

[0039] S3) Simultaneously turn on the probe power supply via the control terminal to activate the temperature data acquisition instrument and measure the temperature of the selected probe.

[0040] S4) After the measured temperature range stabilizes, the programmable linear current source is turned on to heat the selected probe. The K-type thermocouple in the selected probe transmits the collected probe temperature signal to the temperature data acquisition instrument, which then feeds it back to the control terminal. After measuring for 100-150 seconds, a T-lnt curve is obtained, and the measured thermal conductivity is calculated based on the curve.

[0041] S5) The actual thermal conductivity can be obtained by correcting the measured thermal conductivity with the correction factor γ.

[0042] The correction coefficient γ in step S5) is calculated using the following formula:

[0043]

[0044] In the formula, δ is the ratio of the length to the diameter of the selected probe.

[0045] After obtaining the measured thermal conductivity λ 测 Then, the measured thermal conductivity λ is calculated using the following formula. 测 The corrected thermal conductivity λ is obtained by making corrections. 修正 :

[0046] λ 修正 =λ 测 / γ.

[0047] When conducting thermal testing on the heat storage material, before heating, the external environment, the material to be tested 5, and the probe 4 need to be in thermal equilibrium, all at temperature T0. Then, a heating current is applied to the probe 4, causing the temperature of the probe 4 and the surrounding sample to rise. The thermal conductivity of the sample can be calculated based on this temperature rise. Its expression is:

[0048]

[0049] Where C = 1.78, and higher-order terms above the second order are ignored in the hot-wire method, the above equation is transformed into:

[0050]

[0051] Where ΔT(r0,t) is the temperature rise of the probe, in °C;

[0052] q represents the heating power per unit length of the linear heat source, expressed in W / m.

[0053] λ is the thermal conductivity to be determined, in units of W / (m / K);

[0054] t represents the heating time, measured in seconds (s).

[0055] r0 is the diameter of the probe, in meters (m).

[0056] α is the thermal diffusivity of the sample, with units of mm² / s.

[0057] Based on the experimentally obtained ΔT-lnt curve, the relatively linear part of the curve is linearly fitted using the least squares method to obtain a straight line of the form y=kx+b. Combining this with equation (2), we can obtain...

[0058]

[0059] Since the size of probe 4 cannot meet the assumptions required in the heat transfer mathematical model, the final thermophysical parameter measurement results need to be calibrated and corrected for the specific probe size and structure, and the calculation formula for the correction coefficient γ is obtained through calibration and correction.

[0060] In this embodiment, the formula for calculating the correction coefficient γ in step S5) is obtained through the following steps:

[0061] ss1) Using the Fluent simulation method, a large number of simulation calculations were performed on the use of probes of different sizes, and the calculated thermal conductivity was divided by the preset thermal conductivity to obtain a series of coefficients φ related to the probe size;

[0062] ss2) Fit the coefficient φ obtained in step ss1) using Origin to obtain a coefficient formula that is only related to the probe aspect ratio. This coefficient formula is the formula for calculating the correction coefficient γ.

[0063] After obtaining the actual thermal conductivity of the material, the relationship can be used... The specific heat of the sample to be tested can then be obtained.

[0064] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. A plug-and-test probe-type thermal testing method for thermal storage materials, characterized in that, The steps include: S1) Select a probe of appropriate specifications according to the size of the material sample to be tested, and make a sample hole on the material sample to be tested. The diameter of the sample hole is the same as the diameter of the selected probe, and the depth of the sample hole is greater than or equal to the length of the selected probe. The diameter of the selected probe is 3 to 6 mm. S2) Apply thermal grease evenly around the selected probe, and then insert the selected probe into the sample hole punched in step S1). S3) Simultaneously turn on the probe power supply via the control terminal to activate the temperature data acquisition instrument and measure the temperature of the selected probe. S4) After the measured temperature range stabilizes, the programmable linear current source is turned on to heat the selected probe. The K-type thermocouple in the selected probe transmits the collected probe temperature signal to the temperature data acquisition instrument, which then feeds it back to the control terminal. After measuring for 100-150 seconds, a T-lnt curve is obtained, and the measured thermal conductivity is calculated based on the curve. S5) The actual thermal conductivity can be obtained by correcting the measured thermal conductivity with the correction factor γ. The correction factor γ is calculated using the following formula: In the formula, δ is the ratio of the length to the diameter of the selected probe.

2. The plug-and-test probe-type thermal testing method for thermal storage materials according to claim 1, characterized in that, The formula for calculating the correction coefficient γ in step S5) is obtained through the following steps: ss1) Using the Fluent simulation method, a large number of simulation calculations were performed on the use of probes of different sizes, and the calculated thermal conductivity was divided by the preset thermal conductivity to obtain a series of coefficients φ related to the probe size; ss2) Fit the coefficient φ obtained in step ss1) using Origin to obtain a coefficient formula that is only related to the probe aspect ratio. This coefficient formula is the formula for calculating the correction coefficient γ.

3. A system for thermal testing using the plug-and-test probe-type thermal testing method for thermal storage materials as described in claim 1 or 2, characterized in that, The device includes a temperature data acquisition instrument (2), a programmable linear DC power supply (3), a control device (1), a high and low temperature alternating humidity chamber, and a probe (4). The probe (4) is an integrated heating and detection probe. The probe (4) is communicatively connected to the temperature data acquisition instrument (2). The temperature data acquisition instrument (2), the programmable linear DC power supply (3), and the high and low temperature alternating humidity chamber are communicatively connected to the control device (1). The programmable linear DC power supply (3) is electrically connected to the probe (4).

4. The system according to claim 3, characterized in that, The probe (4) includes a probe top and a probe tail, with the lower end of the probe top connected to the top end of the probe tail; the probe tail includes a tube (4-3), a heating wire (4-1), and a thermocouple (4-2), with the heating wire (4-1) and the thermocouple (4-2) respectively disposed inside the tube (4-3), the heating point of the heating wire (4-1) being in close contact with the temperature measuring point of the thermocouple (4-2) and fixed to the bottom inner side of the tube (4-3); the diameter of the tube (4-3) is 3-6 mm.

5. The system according to claim 4, characterized in that, Multiple heating wires (4-1) are arranged axially around the thermocouple (4-2).

6. The system according to claim 5, characterized in that, The multiple heating wires (4-1) and the thermocouples (4-2) are arranged axially at equal intervals.

7. The system according to claim 4, characterized in that, The probe has an I-shaped handle (4-4) at the top, and the vertical part of the I-shaped handle (4-4) has a through hole (4-6). The I-shaped handle is made of 304 stainless steel. The upper end of the heating wire (4-1) and the upper end of the thermocouple (4-2) are connected to the wire through the through hole (4-6).

8. The system according to claim 7, characterized in that, A heat insulation pad (4-5) is provided between the I-shaped handle (4-4) and the upper end of the tube body (4-3), and the heat insulation pad (4-5) is a gasket made of aluminum silicate fiber.

9. The system according to claims 4 to 8, characterized in that, The tube body (4-3) is filled with thermally conductive silicone grease.

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