Mobile portable test system and method for radiation refrigeration net cooling power based on thermoelectric element

Abstract

The invention provides a radiation refrigeration net cooling power mobile portable test system and method based on a thermoelectric element. The system and method are mainly applied to real-time multi-angle net cooling power measurement and analysis of a radiation refrigeration film material in an outdoor environment. The system comprises a device shell, a built-in testing device, a monitoring system, a signal processing system, a data acquisition system, a wireless transmission system, a control system and a mobile terminal software system. The test method comprises the steps of preheating and stabilization, sample installation and software setting, signal processing, signal acquisition, power conversion and result analysis, and realizes rapid and accurate net cooling power measurement of the radiation refrigeration film material. The system has the advantages of being small in size, compact in structure, portable, flexible, easy to move and deploy, high in precision, capable of achieving real-time monitoring and remote regulation and control and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of radiative cooling, and particularly to a radiative cooling net cooling power mobile portable test system and method based on thermoelectric elements, which are specifically applied to the real-time measurement and analysis of the net cooling power of radiative cooling film materials under outdoor multi-angle conditions; it is particularly suitable for portable radiative cooling performance evaluation that requires quick response, real-time monitoring, and remote adjustment of the measurement angle. Background Art

[0002] Radiative cooling refers to the process of heat radiation transfer through the atmospheric window (about 8–13μm) to the cold outer space (about 3K). It can make the surface temperature of an object lower than the ambient temperature without energy consumption, thereby achieving spontaneous cooling at night and even during the day.

[0003] Currently, the evaluation of the net cooling power test of radiative cooling film materials mostly adopts the method of active feedback control heating or complex heat calculation methods, such as calculating through the heat difference of the cooling table or keeping the material temperature the same as the ambient temperature through heating feedback in an adiabatic environment. For example, patent CN116990342A discloses an all-weather radiative cooling material radiant energy power test device and its test method, which calculates the net cooling capacity of the radiative cooling surface per unit area by calculating the heat difference between the inlet and outlet water of the test table and the cooling table per unit area, and then calculates its cooling power in combination with the energy conservation relationship existing on the radiative cooling surface; the literature "In Situ Formation of SiO2 Nanospheres on Common Fabrics for Broadband Radiative Cooling" mentions using a silicone rubber heater to feedback-adjust the film temperature. However, such methods have problems such as complex calculation or feedback control logic, long measurement period, high equipment cost, and difficulty in realizing multi-angle real-time measurement in the actual outdoor environment. In addition, existing measurement methods based on thermoelectric power generation chips are mostly static devices. For example, patent CN115267324A discloses a measurement device and method for radiative cooling cooling power, which indirectly obtains the radiative cooling cooling power by collecting the electric power through a power meter, limited to static measurement or simple single-point data collection in the outdoor environment, lacking a data collection and analysis system suitable for multi-angle, high-precision, mobile portable, and real-time remote monitoring in the outdoor environment.

[0004] Therefore, developing a new type of radiative cooling net cooling power measurement device that integrates thermoelectric element thermoelectric power generation technology, built-in signal processing and data correction, can remotely adjust the measurement angle in real time, and intuitively display data on the mobile terminal has obvious innovation advantages and practical significance. Summary of the Invention

[0005] According to the technical problems existing in the above-mentioned radiation cooling net cooling power test, a mobile and portable test system and method for the radiation cooling net cooling power based on thermoelectric elements are provided. The present invention mainly utilizes the fact that a voltage signal is generated when the temperatures on both sides of the thermoelectric element are different. By collecting and analyzing the voltage signal, the temperature difference and power value can be quickly obtained. Only one calibration is required before applying the thermoelectric element, and the net cooling power test experiment can be carried out infinitely many times. It solves the problems in the prior art such as cumbersome equipment, high cost, fixed angle, and difficulty in real-time and accurate measurement in the outdoor test of the radiation cooling film material, and realizes the rapid detection and evaluation of the net cooling power of the radiation cooling film material.

[0006] The technical means adopted by the present invention are as follows:

[0007] A mobile and portable test system for the radiation cooling net cooling power based on thermoelectric elements, comprising:

[0008] A device housing 1; a protective cover with good transparency or infrared transmittance is provided at the top of the device housing 1, preferably a polyethylene film; a transparent insulating housing is provided on the side wall, preferably a transparent acrylic plate 11, which is used to prevent the interference of environmental factors such as rain and dust and has the functions of dust prevention, wind prevention and waterproofing;

[0009] A test device; placed inside the device housing 1, including an integrated device base 2 with a card slot 3, a rotating rod 4, a column 5, and a stepping motor 7. The card slot 3 is used to place the thermoelectric element 6;

[0010] A monitoring system; placed in the middle of the cross beam inside the device housing 1, facing the test device, and used to collect the video signal of the test device;

[0011] A signal processing system; used to perform low-pass filtering and chopper amplification processing on the current and voltage signals output by the thermoelectric element 6;

[0012] A data acquisition system; collects the current and voltage signals released by the thermoelectric element 6 processed by the signal processing system;

[0013] A wireless transmission system; used to transmit the current and voltage signals of the data acquisition system and the video signal of the monitoring system to the control system through wireless transmission, and the control system receives the control instructions from the mobile software system through wireless transmission;

[0014] A control system; used to process the current and voltage signals from the data acquisition system, convert the voltage data into the radiation cooling net cooling power value of the radiation cooling film material 12 to be measured, calculate the temperature difference according to the formula, and finally form a net cooling power and temperature difference data curve. The control system is also used to encode the video signal from the monitoring system and process the control instructions from the mobile software system;

[0015] Mobile software system; used for real-time display of monitoring images, net cooling power, and temperature difference data curves, and remote control of measurement angles;

[0016] Further, in the test device: the device base 2 is fixed to the bottom surface of the device housing 1, the lower end of the column 5 is fixed to the device base 2, the top end of the column 5 is rotatably connected to the rotating rod 4, a fixed card slot 3 is provided on the rotating rod 4, one end of the rotating rod 4 is connected to the stepping motor 7, and the rotating rod 4 is driven to rotate by the stepping motor 7, and the rotation range is 0 to 90°; the middle of the card slot 3 is hollowed out for placing the thermoelectric element 6, the top of the thermoelectric element 6 is attached to the radiation cooling film material 12 to be measured through thermal conductive glue, and the bottom is directly exposed to the environment to form a temperature difference.

[0017] Even further, the stepping motor 7 is connected to the control system through a controller 17 supporting the stepping motor, and the control system controls the rotation of the stepping motor 7 by receiving wireless communication tasks from the mobile software system.

[0018] Further, the monitoring system uses a camera assembly 8;

[0019] Further, the signal processing system integrates a low-pass filter 13, a chopper amplifier 14, and a signal shielding net 15. Among them, the low-pass filter 13 is used to filter out high-frequency noise, the chopper amplifier 14 is used to amplify weak signals, and the signal shielding net 15 is used to reduce electromagnetic interference;

[0020] Further, the data acquisition system is a high-precision data acquisition card 16.

[0021] Further, the wireless transmission system uses an LTE wireless cellular data transmission module.

[0022] Further, the control system uses a main control unit 18;

[0023] Even further, the control system further includes a voltage stabilizing power supply module for ensuring stable power supply in the outdoor environment.

[0024] The present invention also provides a method for testing the net cooling power of radiative cooling based on a thermoelectric element, which is realized by a mobile and portable test system for the net cooling power of radiative cooling based on a thermoelectric element, and includes two parts: signal calibration and testing of the thermoelectric element 6. The testing includes the following steps:

[0025] Step S1: Preheating and stabilization: Place the test device in the outdoor environment to make the internal temperature distribution of the test device tend to be stable;

[0026] Step S2: Sample Installation and Software Setup: Paste the radiation cooling film material 12 to be measured onto the test surface of the thermoelectric element 6, and use the card slot 3 to press it tightly to ensure close contact. After setting the test angle condition in the mobile software system, start the test device and the monitoring system;

[0027] Step S3: Signal Processing: Use a signal processing system to perform low-pass filtering and chopper amplification on the current and voltage signals output by the thermoelectric element 6;

[0028] Step S4: Signal Acquisition: Through the data acquisition system, collect the current and voltage signals output by the thermoelectric element 6 processed by the signal processing system in real time, and synchronously collect the video signals collected by the monitoring system, and upload them to the mobile software system through wireless transmission via the main control unit 18.

[0029] Step S5: Power Conversion: Convert the collected current and voltage signals into the net cooling power of the radiation cooling film material 12 to be measured based on a pre-established calibration curve or model. At the same time, calculate the temperature difference through this voltage signal using the formula, that is, the temperature difference between the ambient temperature and the temperature of the radiation cooling film material 12 to be measured;

[0030] Step S6: Result Analysis: Filter, statistically analyze the net cooling power obtained by power conversion, or use a multivariable regression algorithm for correction to obtain the real-time or interval average net cooling power of the radiation cooling film material 12 to be measured.

[0031] Further, the calibration curve or model in the step S5 is obtained by measuring the output voltage signal of the thermoelectric element 6 under known thermal power / cooling power input conditions, and establishing the corresponding relationship between the voltage signal and the power by using the multi-point sampling and curve fitting method; the method for obtaining the calibration curve or model is: paste the electric heating sheet 19 connected to the programmable DC power supply 20 on the bottom of the thermoelectric element 6, measure the voltage signal of the thermoelectric element 6 at different heating powers, establish a voltage-power calibration curve or calibration model, and realize accurate conversion of test data. The calibration range is 0-200 W / m 2 。

[0032] Further, the temperature difference calculation formula in the step S4 utilizes the working principle of the thermoelectric element 6 - the Seebeck effect; according to the Seebeck effect, when the data acquisition card 16 measures the voltage with a high input impedance, the circuit is approximately in an open circuit state at this time, and the thermoelectric element 6 outputs the Seebeck voltage. The formula is:

[0033] V = α * ΔT

[0034] Where V is the output voltage (unit: V), α is the Seebeck coefficient (unit: V / K), and ΔT is the real-time temperature difference between the film material and the environment (unit: K).

[0035] Furthermore, the radiative cooling net cooling power test method supports multiple thermoelectric elements 6 to work independently and simultaneously collect data in real time, and can perform parallel comparative tests on multiple radiative cooling film materials 12 or different formulations under the same environmental conditions, significantly improving test efficiency and accuracy.

[0036] Furthermore, if it is necessary to obtain the ambient temperature value and the sample temperature value, the ambient temperature can be obtained by adding a temperature sensor in the device, and the sample temperature value can be obtained by the difference.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] The device of the present invention uses thermoelectric elements to achieve passive measurement of the net cooling power of radiative cooling, without the need for additional precision temperature measurement equipment and traditional active feedback heating control. It simplifies the test system structure, reduces the complexity of the feedback control logic during the measurement process, and significantly improves the stability and reliability of the measurement device.

[0039] The device of the present invention uses a stepper motor to drive a rotating rod connected to the card slot, which can remotely and accurately adjust the test angle in real time, realizing convenient measurement and analysis of radiant cooling performance at different angles, effectively overcoming the limitation of traditional fixed-angle measurement devices that cannot adapt to the testing requirements of different outdoor conditions.

[0040] The device of the present invention has a compact structure, small size, and is lightweight and portable. It is very suitable for long-term continuous testing in real outdoor environments. It overcomes the shortcomings of existing devices such as large size, complex structure, and difficulty in movement and deployment, and improves the convenience of outdoor real-time testing.

[0041] The device of the present invention has a built-in low-pass filter and a chopper amplifier, and combined with signal shielding measures, it effectively reduces outdoor environmental noise and interference, improves the acquisition accuracy and stability of the thermoelectric element output signal, and ensures the reliability and accuracy of the data.

[0042] The device of the present invention is pre-calibrated with known power components to establish an accurate calibration curve or model, thereby ensuring the accuracy of the conversion between electrical signals and net cooling power, greatly improving the accuracy and credibility of the measurement data, and avoiding the cumbersome calibration process in traditional complex feedback measurements.

[0043] The present invention is equipped with mobile control software, which can view monitoring videos in real time, collect data charts, and remotely send test angle control instructions, realizing the visualization of the test process, real-time data collection, and convenient adjustment of test conditions, effectively improving the efficiency of the actual performance evaluation of radiant refrigeration materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1This is a schematic diagram of the overall device of the present invention.

[0045] Figure 2 This is an exploded view of the card slot part of the device of the present invention.

[0046] Figure 3 This is a schematic structural diagram of the present invention.

[0047] Figure 4 This is a schematic diagram of the calibration structure of the thermoelectric element described in the present invention.

[0048] In the figure, 1 is the device housing; 2 is the device base; 3 is the card slot; 4 is the rotating rod; 5 is the column; 6 is the thermoelectric element; 7 is the stepper motor; 8 is the camera assembly; 9 is the cable hole; 10 is the hardware device area; 11 is the transparent acrylic plate; 12 is the radiation cooling film material to be tested; 13 is the low-pass filter; 14 is the chopper amplifier; 15 is the signal shielding net, 16 is the data acquisition card; 17 is the controller supporting the stepper motor; 18 is the main control unit; 19 is the electric heating sheet; 20 is the programmable DC power supply.

[0049] Among them, the hardware device area 10 includes a low-pass filter 13, a chopper amplifier 14, a signal shielding net 15, a data acquisition card 16, a controller supporting the stepper motor 17, a main control unit 18, as well as an LTE wireless cellular data transmission module and a voltage stabilizing power supply module. Specific implementation manners

[0050] The present invention will be further described in detail below with reference to the accompanying drawings.

[0051] As Figure 1 , shown in 2, 3, 4, the present invention is a mobile portable test system for the net cooling power of radiation cooling based on a thermoelectric element, including a device housing 1, a device base 2, a card slot 3, a rotating rod 4, a column 5, a thermoelectric element 6, a stepper motor 7, a camera assembly 8, a cable hole 9, a transparent acrylic plate 11, a radiation cooling film material to be tested 12, a low-pass filter 13, a chopper amplifier 14, a signal shielding net 15, a data acquisition card 16, a controller supporting the stepper motor 17, a main control unit 18, an electric heating sheet 19, and a programmable DC power supply 20. The device is placed outdoors, and the top of the device housing 1 is covered with a transparent PE film, which helps to prevent wind and water, and has good infrared transmittance; the side wall of the device housing 1 is covered with a transparent acrylic plate 11, which helps to prevent interference from wind factors; the column 5 is fixed on the device base 2 inside the device housing 1, and the column 5 can be designed to be adjustable in height according to needs. The top is connected to the card slot 3, the rotating rod 4 and the stepper motor 7. The thermoelectric element 6 is arranged in the card slot 3, and the rotating rod 4 is driven by the stepper motor 7 to rotate. The angle of the card slot 3 can be adjusted through the rotating rod 4 to facilitate testing the influence of different angles on the net cooling power.

[0052] Before the first test, the thermoelectric element 6 needs to be calibrated, asFigure 4 As shown, the electric heating sheet 19 with a known resistance is pasted at the bottom end of the thermoelectric element 6 through a thermal conductive adhesive, and the two are fixed in the card slot 3. At this time, the two should be in close contact; the electric heating sheet 19 is connected to the programmable DC power supply 20, and the thermoelectric element 6 is successively connected to the low-pass filter 13, the chopper amplifier 14, and the data acquisition card 16. The signal shielding net 15 is respectively coated at the above-mentioned connecting wires, and the programmable DC power supply 20 and the data acquisition card 16 are connected to the main control unit 18. The input voltage of the electric heating sheet 19 can be adjusted through the programmable DC power supply 20, and the heating power range of the electric heating sheet 19 is controlled within 0 - 200 W / m 2 , collect the electrical signals and perform quadratic or polynomial correction fitting on the two to obtain their corresponding relationship.

[0053] During the test, place the device in an outdoor environment. After turning on the machine, wait for 10 minutes to make the system reach a temperature stable state; paste the radiation cooling film material 12 to be measured at the top end of the thermoelectric element 6 through a thermal conductive adhesive, and place it in the card slot 3. At this time, the two should be in close contact; after setting the test angle through the mobile terminal, start the data acquisition program, record the output voltage data of the thermoelectric element 6 every 5 seconds, and perform a correction function transformation on the collected data to obtain the net cooling power of the radiation cooling film material 12 to be measured, and synchronously calculate the temperature difference.

[0054] Use a commercial white PP film as the radiation cooling film material for the net cooling power test experiment. Select a thermoelectric element with a Seebeck coefficient of about 250 μV / K and a size of 4 cm × 4 cm. In the calibration process, it is measured that the voltage-net cooling power fitting is approximately a straight line, and the formula is:

[0055] P = -0.1035 + 60.0557U OC

[0056] Among them, P is the electric heating power, that is, the net cooling power of the film material, with the unit of W / m 2 ; U OC is the open-circuit voltage output by the thermoelectric element, with the unit of mV.

[0057] Obtain the corresponding relationship between the voltage signal value, the temperature difference, and the net cooling power at different time periods. Select some data results as shown in Table 1 (the results are all reserved to two decimal places).

[0058] Table 1 Radiation cooling test data of white commercial PP film

[0059]

[0060]

[0061] Specifically, if it is necessary to compare the radiative cooling performance of multiple different radiative cooling film materials 12 to be measured, multiple independent thermoelectric element modules can be placed, each thermoelectric element module corresponding to a sample to be measured, and the output signals of each module are collected uniformly through a multi-channel data acquisition card 7, so as to obtain the comparison results of the net cooling power of multiple materials under the same environmental conditions at the same time.

[0062] The above embodiments are only used to illustrate the technical principles and advantages of the present invention, and do not limit the protection scope of the present invention. Any equivalent replacement or simple deformation within the spirit and principle of the present invention shall be regarded as falling within the protection scope of the present invention.

Claims

1. A mobile portable test system for the net cooling power of radiative cooling based on a thermoelectric element, characterized in that, Comprising: A device housing (1); a protective cover with good transparency or infrared transmittance is provided at the top of the device housing (1), and a transparent insulating housing is provided on the side wall; A testing device; Placed inside the device housing (1), including an integrated device base (2) with a card slot (3), a rotating rod (4), a column (5), and a stepper motor (7). The card slot (3) is used to place a thermoelectric element (6); A monitoring system; placed in the middle of the inner crossbeam of the device housing (1), facing the testing device, for collecting video signals of the testing device; A signal processing system; used for low-pass filtering and chopping amplification processing of the current and voltage signals output by the thermoelectric element (6); A data acquisition system; acquiring the current and voltage signals released by the thermoelectric element (6) processed by the signal processing system; A wireless transmission system; Used to transmit the current and voltage signals of the data acquisition system and the video signals of the monitoring system to the control system by wireless transmission, and the control system receives control instructions from the mobile software system by wireless transmission; A control system; used for processing the current and voltage signals from the data acquisition system, converting the voltage data into the net cooling power value of the radiation cooling film material (12) to be measured, calculating the temperature difference according to the formula, and finally forming a net cooling power and temperature difference data curve. The control system is also used for encoding the video signals from the monitoring system and processing the control instructions from the mobile software system; A mobile software system; used for real-time displaying the monitoring screen, the net cooling power and temperature difference data curve, and remotely controlling the measurement angle.

2. The portable test system for moving the net cooling power of radiative cooling based on a thermoelectric element according to claim 1, wherein In the testing device: the device base (2) is fixed to the bottom surface of the device housing (1), the lower end of the column (5) is fixed to the device base (2), the top end of the column (5) is rotatably connected to the rotating rod (4), the card slot (3) is fixed on the rotating rod (4), one end of the rotating rod (4) is connected to the stepper motor (7), and the rotating rod (4) is driven to rotate by the stepper motor (7), and the rotation range is 0 - 90°; the middle of the card slot (3) is hollowed out for placing the thermoelectric element (6), the top of the thermoelectric element (6) is attached to the radiation cooling film material (12) to be measured through a thermal conductive adhesive, and the bottom is directly exposed to the environment to form a temperature difference.

3. A radiation cooling net cooling power mobile portable test system based on a thermoelectric element according to claim 1, characterized in that, The monitoring system uses a camera module (8); the data acquisition system is a high-precision data acquisition card (16); the wireless transmission system uses an LTE wireless cellular data transmission module; the control system uses a main control unit (18).

4. A radiation cooling net cooling power mobile portable test system based on a thermoelectric element according to claim 1, characterized in that, The signal processing system is integrated with a low-pass filter (13), a chopping amplifier (14), and a signal shielding net (15). Among them, the low-pass filter (13) is used to filter out high-frequency noise, the chopping amplifier (14) is used to amplify weak signals, and the signal shielding net (15) is used to reduce electromagnetic interference.

5. A radiation cooling net cooling power mobile portable test system based on a thermoelectric element according to claim 2, 3 or 4, characterized in that, The stepper motor (7) is connected to the control system through a controller (17) supporting the stepper motor, and the control system controls the rotation of the stepper motor (7) by receiving wireless communication tasks from the mobile software system; the control system also includes a voltage stabilizing power supply module for ensuring stable power supply in the outdoor environment.

6. A method for mobile portable testing of the net cooling power of radiative cooling based on a thermoelectric element using a mobile portable testing system for the net cooling power of radiative cooling based on a thermoelectric element according to any one of claims 1-5, characterized in that, Including the following steps: Step S1: Preheating and Stabilization: Place the test device in an outdoor environment to make the internal temperature distribution of the test device tend to be stable; Step S2: Sample Installation and Software Setting: Paste the radiation cooling film material (12) to be tested onto the test surface of the thermoelectric element (6), and press it tightly using the card slot (3) to ensure close contact. After setting the test angle condition in the mobile software system, start the test device and the monitoring system; Step S3: Signal Processing: Use a signal processing system to perform low-pass filtering and chopper amplification on the current and voltage signals output by the thermoelectric element (6); Step S4: Signal Acquisition: Through the data acquisition system, collect the current and voltage signals output by the thermoelectric element 6 processed by the signal processing system in real time, and synchronously collect the video signals collected by the monitoring system, and upload them to the mobile software system through wireless transmission via the main control unit (18); Step S5: Power Conversion: Convert the collected current and voltage signals into the net cooling power of the radiation cooling film material (12) to be tested based on a pre-established calibration curve or model. At the same time, calculate the temperature difference using the formula through this voltage signal, that is, the temperature difference between the ambient temperature and the temperature of the radiation cooling film material (12) to be tested; Step S6: Result Analysis: Filter, statistically analyze the net cooling power obtained by power conversion, or use a multivariate regression algorithm for correction to obtain the real-time or interval average net cooling power of the radiation cooling film material (12) to be tested.

7. The method according to claim 6, wherein The calibration curve or model described in step S5 is obtained by measuring the output voltage signal of the thermoelectric element (6) under known thermal power / cooling power input conditions, and establishing the corresponding relationship between the voltage signal and the power by means of multi-point sampling and curve fitting; the method for obtaining the calibration curve or model is: pasting the electric heating sheet (19) connected to the programmable DC power supply (20) at the bottom of the thermoelectric element (6), measuring the voltage signal of the thermoelectric element (6) at different heating powers, establishing a voltage-power calibration curve or calibration model, realizing accurate conversion of test data, and the calibration range is 0 to 200 W / m 2 .

8. The method according to claim 6, wherein The temperature difference calculation formula in Step S4 utilizes the working principle of the thermoelectric element (6) - the Seebeck effect; according to the Seebeck effect, when the data acquisition card (16) measures the voltage with a high input impedance, the circuit is approximately in an open circuit state at this time, and the thermoelectric element (6) outputs the Seebeck voltage. The formula is: V = α * ΔT where V is the output voltage, α is the Seebeck coefficient, and ΔT is the real-time temperature difference between the film material and the environment.

9. The method according to claim 6, wherein The radiation cooling net cooling power test method described supports multiple thermoelectric elements (6) to work independently and collect data in real time. It can perform parallel comparison tests on multiple radiation cooling film materials (12) or different formulations under the same environmental conditions at the same time, significantly improving the test efficiency and accuracy.

10. The method according to claim 6, wherein If it is necessary to obtain the ambient temperature value and the sample temperature value, the ambient temperature can be obtained by adding a temperature sensor in the device, and the sample temperature value can be obtained by taking the difference.

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