Method for monitoring and evaluating service performance of building ceramic radiant refrigeration

Abstract

The application relates to a kind of monitoring and evaluation methods of building ceramic radiation refrigeration service performance, it is related to the testing technical field of building ceramic photo-thermal performance, the method includes covering radiation refrigeration building ceramic sample on the top of sample cavity, covering reference sample on the top of control cavity;Triggering irradiance meter and psychrometer to synchronously collect solar irradiance, ambient temperature and humidity, triggering infrared thermometer and infrared thermal imager to measure the temperature of the upper surface of radiation refrigeration building ceramic sample and the surface distribution of temperature, triggering total heat flow sensor and radiant heat flow sensor to measure the total heat flow and net radiant heat flow of the upper surface of radiation refrigeration building ceramic sample;Based on the sum of the surface thermal radiation power of radiation refrigeration building ceramic sample, absorbed solar radiation power and heat conduction and heat convection power between surrounding environment, the theoretical net radiation refrigeration power of radiation refrigeration building ceramic sample is calculated.

Description

Technical Field

[0001] This invention relates to the field of testing technology for the photothermal properties of building ceramics, and in particular to a method for monitoring and evaluating the radiative cooling performance of building ceramics. Background Technology

[0002] Radiative cooling technology utilizes outer space as a natural heat sink, radiating heat from objects into space through the atmosphere and reflecting energy back to the outside world, thereby achieving self-cooling. This technology boasts advantages such as no additional energy consumption, no need for refrigerants, and no pollutant emissions, making it significant for mitigating the urban heat island effect and achieving building energy conservation and carbon reduction goals. Traditional radiative cooling materials (such as coatings, films, and other organic materials) suffer from poor weather resistance, insufficient decorative properties, and difficulty in long-term, large-scale application in building envelopes. Building ceramic slabs, as a widely used building decoration material, can combine radiative cooling performance with the acid and alkali resistance, aging resistance, and rich decorative properties of ceramic materials through compositional and structural design of the ceramic glaze layer. Currently, monitoring and evaluation methods for radiative cooling performance mainly focus on qualitative judgment or semi-quantitative macroscopic assessment of the cooling effect of sheet-like materials such as films, coatings, and fabrics, primarily characterizing the cooling effect through material temperature monitoring and recording of simple environmental parameters. For example, some methods employ passive testing, directly exposing samples to natural or simulated laboratory environments. The surface temperature of the coating or fabric sample is measured at a single point using thermocouples or infrared thermometers, and compared to the ambient temperature or the surface temperature of ordinary materials. The temperature difference is used to determine the cooling effect. Other methods involve applying a thermally conductive copper plate and heating elements to the back side of the radiation-cooled coating or thin film material under test. The heating elements raise the temperature of the back side of the material until it matches the ambient temperature, and the cooling power of the material is calculated using the heating power of the heating elements.

[0003] However, existing methods for testing radiative cooling performance primarily target thin films, coatings, or fabrics, which typically exhibit sheet-like structures with uniform composition and structure. Compared to these sheet-like radiative cooling materials, radiative cooling building ceramics have larger geometric dimensions, poorer thermal conductivity in the body layer, and diverse glaze decorations leading to poor uniformity of the cooling glaze layer. This makes it difficult for existing techniques to accurately and reliably test and evaluate the radiative cooling performance of building ceramics. First, in real-world usage environments, the low thermal conductivity of the body of building ceramic samples results in temperature differences between the upper and lower surfaces, rendering existing sample temperature measurement and material cooling power testing methods inapplicable. Second, existing temperature measurement methods cannot achieve real-time in-situ monitoring of the global and localized temperatures of multi-specification and multi-style building ceramic samples. The testing dimension is limited, lacking characterization methods for the thermal field distribution on the sample surface and failing to identify uneven heat dissipation caused by microscopic defects in the building ceramic material. Third, current testing methods cannot eliminate the interference of environmental temperature fluctuations and the configuration of the monitoring and testing equipment on the test results. The lack of a control group for temperature measurements under the same testing environment further reduces the accuracy and versatility of the test results. Existing testing technologies cannot assess and quantify the effective air cooling capacity of building ceramics, as well as the energy savings and effective cooling power under service conditions. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method for monitoring and evaluating the radiative cooling performance of building ceramics. By setting up a comparative test structure with a sample chamber and a control chamber, and combining multiple measurement methods such as infrared thermometers, infrared thermal imagers, total heat flux sensors, and radiative heat flux sensors, the surface temperature distribution, theoretical net radiative cooling power, heat dissipation uniformity, effective air cooling capacity, cooling energy savings, and effective cooling power of building ceramic samples can be accurately measured, thereby achieving comprehensive, accurate, and reliable monitoring and evaluation of the radiative cooling performance of building ceramics.

[0005] To achieve the above objectives, the present invention adopts the following technical solution.

[0006] A method for monitoring and evaluating the radiative cooling performance of building ceramics includes: Prepare a sample chamber and a control chamber, wherein the sample chamber and the control chamber are both insulated cavities with cavities. A temperature sensor, a cooling chip and a cooling fan are installed inside the sample chamber and the control chamber respectively. An infrared thermometer, an infrared thermal imager, a thermo-hygrometer and an irradiance meter are installed outside the cavities. A radiation-cooled building ceramic sample is placed on top of the sample chamber, and a reference sample is placed on top of the control chamber, wherein the reference sample is a conventional building ceramic. A total heat flux sensor and a radiative heat flux sensor are installed on the upper surface of the radiation-cooled building ceramic sample. The system triggers the irradiance meter and the temperature and humidity meter to synchronously collect solar irradiance, ambient temperature and humidity; it triggers the infrared thermometer and the infrared thermal imager to measure the surface temperature and surface distribution of the radiation-cooled building ceramic sample; and it triggers the total heat flux sensor and the radiative heat flux sensor to measure the total heat flux and net radiative heat flux of the surface of the radiation-cooled building ceramic sample. Based on the surface thermal radiation power, absorbed solar radiation power, and the sum of thermal conduction and convection power between the radiation-cooled building ceramic sample and the surrounding environment, the theoretical net radiation cooling power of the radiation-cooled building ceramic sample is calculated, wherein the sum of thermal conduction and convection power is determined by the difference between the total heat flow and the net radiation heat flow.

[0007] Furthermore, the above method also includes: Remove the total heat flow sensor and the radiative heat flow sensor from the upper surface of the radiation-cooled architectural ceramic sample; Temperature zones were divided on the upper surface of the radiation-cooled building ceramic sample; The infrared thermal imager is triggered to acquire the surface temperature distribution of the radiation-cooled building ceramic sample. The standard deviation of the surface temperature distribution of the radiation-cooled building ceramic sample was calculated to quantitatively characterize the heat dissipation uniformity of the radiation-cooled building ceramic sample.

[0008] Furthermore, in the above method, the size of the temperature zone is 100 mm × 100 mm to 200 mm × 200 mm, and the number of temperature zones collected for a single radiation-cooled building ceramic sample is not less than 16.

[0009] Furthermore, the above method also includes: Triggering the temperature sensors and cooling fans in the sample chamber and the control chamber; Collect and record the temperature curves of the sample chamber and the control chamber during the service cycle; Based on the temperature difference between the sample chamber and the control chamber, the chamber volume, air density, and air specific heat capacity, the effective air cooling capacity of the radiation-cooled building ceramic sample is calculated.

[0010] Furthermore, the above method also includes: Place the sample chamber and the control chamber in an indoor environment and remove the radiation-cooled building ceramic sample and the reference sample. Reinstall them after thermal equilibrium is reached. Set a target temperature, which is lower than the average ambient temperature; The temperature sensor, the cooling chip, and the cooling fan in the sample chamber and the control chamber are triggered; Based on the measured air temperature inside the cavity and the target temperature, the power of the cooling chip is dynamically adjusted by PID control to achieve consistency between the air temperature inside the cavity and the target temperature; The operating voltage and current of the cooling chip are recorded synchronously. Based on the integral of the difference in electrical power between the cooling element in the control chamber and the sample chamber over the test period, the energy savings of the radiation-cooled building ceramic sample are calculated.

[0011] Furthermore, the above method also includes: Based on the performance coefficient of the cooling element and the energy savings in cooling, the effective cooling power of the radiation-cooled building ceramic sample is calculated.

[0012] Furthermore, in the above method, the surface thermal radiation power is calculated based on the average temperature of the upper surface of the radiation-cooled architectural ceramic sample, the emissivity of the atmospheric window, and the ratio of the energy radiated by the blackbody in the atmospheric window to the total energy across the entire wavelength range, wherein the ratio is determined by the average temperature according to Planck's radiation law.

[0013] Furthermore, in the above method, the insulation cavity is a foam box, and the material of the foam box is polystyrene foam board, polyurethane foam board or phenolic foam board, with a thermal conductivity of not more than 0.035 W / (m·K), and the thickness of the insulation material on the outer wall of the cavity is not less than 200 mm.

[0014] Furthermore, in the above method, the sample chamber and the control chamber have the same geometric dimensions and materials, and the outside of the heat-insulating chamber is wrapped with tin foil to reduce the influence of ambient heat on the test.

[0015] Furthermore, in the above method, the distance between the infrared thermometer and the infrared thermal imager and the radiation-cooled building ceramic sample is not less than 500 mm.

[0016] In summary, compared with the prior art, the present invention has at least one of the following beneficial technical effects: The present invention provides a method for monitoring and evaluating the radiative cooling service performance of building ceramics. By setting up a comparative test structure with a sample chamber and a control chamber, the interference of ambient temperature fluctuations and test device configuration on the test results is effectively eliminated. By simultaneously installing a total heat flux sensor and a radiative heat flux sensor on the upper surface of the radiatively cooled building ceramic sample, the total heat flux and net radiative heat flux can be measured separately, thereby accurately obtaining the sum of heat conduction and heat convection power. Based on the surface thermal radiation power, absorbed solar radiation power, and heat conduction and heat convection power, the theoretical net radiative cooling power can be calculated. This method, combined with an infrared thermometer and an infrared thermal imager, realizes real-time in-situ monitoring of the surface temperature and its surface distribution of building ceramic samples. It overcomes the shortcomings of the existing single-point temperature measurement method, which cannot characterize the surface thermal field distribution of large-size building ceramic samples, and provides a reliable technical means for accurately evaluating the radiative cooling service performance of building ceramics. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a test flowchart of a specific embodiment of the method for monitoring and evaluating the service performance of building ceramics under radiative cooling according to the present invention.

[0019] Figure 2 This is a general structural diagram of a specific embodiment of the radiative cooling service performance testing platform for building ceramics of the present invention.

[0020] Figure 3 This is a schematic diagram of the sample chamber and control chamber structure of a specific embodiment of a radiation-cooled service performance testing platform for building ceramics according to the present invention.

[0021] Figure 4 This is a schematic diagram of the overall operating circuit of the accessories of a specific embodiment of the radiative cooling service performance testing platform for building ceramics of the present invention.

[0022] Figure 5 This is a schematic diagram of the PID control system for a radiant cooling performance testing platform for building ceramics according to a specific embodiment of the present invention.

[0023] Figure 6 This is a graph showing the calculated values ​​and fitted curves of β8~13 in the temperature range of 223 K~333 K.

[0024] Figure 7This is a real photograph of a test sample from a specific embodiment of the radiation-cooled building ceramics service performance testing platform of the present invention. The left side shows radiation-cooled building ceramics, and the right side shows conventional building ceramics.

[0025] Figure labels: 1. Radiation-cooled building ceramics; 2. Conventional building ceramics; 3. Total heat flux sensor; 4. Radiative heat flux sensor; 5. Infrared thermal imager; 6. Infrared thermometer; 7. Irradiance meter; 8. Thermohygrometer; 9. Hot end fan of cooling element; 10. Shelf; 11. Temperature sensor; 12. Cooling element; 13. Cold end fan of cooling element; 14. Aluminum foil; 15. Foam box; A. Sample group; B. Control group. Detailed Implementation

[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application.

[0027] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments of this application. Furthermore, the descriptions of each embodiment in the following embodiments have their own emphasis; for parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0028] The method steps described in this embodiment of the invention can be executed in the order described in the specific implementation, or the execution order of each step can be adjusted according to actual needs, provided that the technical problem can be solved. These are not listed one by one here.

[0029] The present invention will be further described in detail below with reference to the accompanying drawings.

[0030] This invention aims to improve the accuracy and applicability of quantitative testing of the service performance of radiative cooling building ceramics, addressing the technical shortcomings of existing technologies such as single temperature control and poor quantitative accuracy. It proposes a method for monitoring and evaluating the service performance of radiative cooling building ceramics, comprising the following steps. The testing procedure for the service performance of radiative cooling building ceramics can be referred to... Figure 1 .

[0031] Step 1: Prepare two foam boxes with a certain volume cavity as the sample chamber and the control chamber; install a temperature sensor 11, a cooling chip 12, and a cooling fan inside the two chambers; install a total heat flow sensor 3 and a radiative heat flow sensor 4 on the upper surface of the radiation-cooled building ceramic 1; install an infrared thermometer 6, an infrared thermal imager 5, a thermo-hygrometer 8, and an irradiance meter 7 on the outside of the chambers; cover the top of the sample chamber and the control chamber with the radiation-cooled building ceramic sample and a reference sample of the same size, respectively, ensuring excellent sealing between the sample and the upper surface of the chamber. The overall structure of the test platform can be referred to... Figure 2 The cavity structures of the sample chamber and control chamber can be referred to Figure 3 .

[0032] The sample chamber consists of an insulated cavity and a radiation-cooled building ceramic 1 sample. The atmospheric window emissivity and solar reflectance of the radiation-cooled building ceramic 1 sample should both be no less than 0.92. The control chamber consists of an insulated cavity and a reference sample. The reference sample is conventional building ceramic 2, that is, the ceramic product that the radiation-cooled building ceramic 1 replaces in actual use.

[0033] Step 2: Trigger the simultaneous acquisition of solar irradiance, ambient temperature, and humidity by the irradiance meter 7 and the thermo-hygrometer 8; trigger the infrared thermometer 6 and the infrared thermal imager 5 to measure the surface temperature of the sample and its surface distribution; trigger the total heat flux sensor 3 and the radiative heat flux sensor 4 to measure the total heat flux and net radiative heat flux of the working surface (upper surface) of the radiation-cooled building ceramic 1. The overall operating circuit of the infrared thermometer 6, infrared thermal imager 5, thermo-hygrometer 8, irradiance meter 7, total heat flux sensor 3, radiative heat flux sensor 4, and the cooling element 12 can be referred to... Figure 4 The theoretical net radiative cooling power of the radiative-cooled building ceramic 1 is calculated using equation (1): (1); In formula (1): P net The theoretical net radiative cooling power (W / m²) of radiative-cooled building ceramics 1 2 ); P rad Thermal radiation power (W / m²) of the surface of radiation-cooled building ceramic 1 2 ), can be calculated using the following formula (2); P solar Solar radiation power absorbed by the surface of radiation-cooled building ceramic 1 (W / m²) 2 ), can be calculated using the following formula (3); P cond+conv The sum of heat conduction and heat convection power between radiative cooling building ceramics 1 and the surrounding environment (W / m²) 2 ), can be calculated using the following formula (4).

[0034] Equation (2) is: (2) In formula (2): β 8~13 Let be the ratio of the energy radiated by the blackbody through the atmospheric window at the sample surface temperature to the total energy across the entire wavelength range. This value can be calculated using Planck's radiation law. To simplify the calculation, we can... β 8~13 Simplified to 0.325 (the ratio of the energy radiated by a blackbody at 303 K / 30℃ through an atmospheric window to the total energy across the entire wavelength range, dimensionless), it can be derived from... Simplify the calculation. T The average temperature (K) of the upper surface of the radiation-cooled building ceramic 1 can be measured by an infrared thermal imager; σ It is the Stefan-Boltzmann constant. σ = 5.67 × 10 -8 W / (m 2 ·K 4 ); ε 8~13 The atmospheric window emissivity (dimensionless) of the radiative cooling building ceramic 1 can be measured by T / CECS 10378-2024 "Radiative Cooling Coatings for Buildings".

[0035] Equation (3) is: (3) In formula (3): I solar Solar irradiance (W / m 2 (), can be measured by a radiometer; ρ The solar reflectance (dimensionless) of the radiation-cooled building ceramic 1 can be measured by JG / T 235-2014 "Building Reflective Thermal Insulation Coatings".

[0036] Equation (4) is: (4) In equation (4): Q Total heat flux (W / m²) on the surface of radiatively cooled building ceramic 1 2 (), which can be measured by the total heat flux sensor 3; Q r Net radiative heat flux (W / m²) received by the upper surface of the radiative-cooled building ceramic 1 2 ), which can be measured by the radiative heat flux sensor 4.

[0037] Step 3: Remove the total heat flux sensor 3 and the radiative heat flux sensor 4 from the upper surface of the radiatively cooled building ceramic 1, divide the upper surface of the radiatively cooled building ceramic 1 into temperature zones, trigger the infrared thermal imager 5 again, collect the surface temperature distribution of the radiatively cooled building ceramic 1, and calculate the standard deviation of the surface temperature distribution of the radiatively cooled building ceramic 1 using the following formula (5). ): (5) In formula (5): n Number of temperature zones (dimensionless); T i Let be the surface temperature (K) of the i-th temperature zone; for n The average surface temperature (K) of each temperature zone.

[0038] in, The heat dissipation uniformity of radiation-cooled building ceramic 1 can be quantitatively characterized. The smaller the value, the better the heat dissipation uniformity of the radiation-cooled building ceramic 1.

[0039] The temperature zone size is 100 mm × 100 mm ~ 200 mm × 200 mm, and the number of temperature zones collected for a single radiation-cooled building ceramic sample is no less than 16.

[0040] In addition, the temperature field distribution of any area and the entire surface of the radiation-cooled building ceramic 1 sample can be measured using an infrared thermal imager 5, thereby qualitatively evaluating the heat dissipation uniformity of the radiation-cooled building ceramic 1.

[0041] In some implementations, if a single infrared thermometer cannot measure the temperature of the entire area, multiple infrared thermometers can be arranged to achieve temperature measurement of multiple zones of radiation-cooled building ceramics. The standard deviation of its surface temperature distribution can then be calculated using equation (5), thereby quantitatively characterizing the heat dissipation uniformity of radiation-cooled building ceramics.

[0042] Step 4: Trigger the temperature sensors and cooling fans in the sample chamber and control chamber, collect and record the air temperature curves of the sample chamber and control chamber during the service cycle, and calculate the effective air cooling capacity of the radiation-cooled building ceramics using the following formula (6). Q air ): (6) In formula (6): Q air-t In the testing cycle t The effective air cooling capacity (J / m²) of radiative cooling building ceramics 2 ); cThe specific heat capacity of air at constant pressure can be taken as 1008 J / (kg·K) for simplifying calculations; ρ air The density of the air inside the cavity under normal pressure conditions can be taken as 1.205 kg / m³. 3 V is the internal volume of the cavity (m³). 3 The dimensions can be calculated from the geometry of the cavity; T 样品腔 T represents the average air temperature (°C) inside the sample chamber. 对照腔 The average air temperature (°C) inside the control cavity; t The temperature curve acquisition time (h) represents the test period; A represents the surface area of ​​the test sample (m²). 2 ).

[0043] Q air-t Closely related to the testing period, the testing period should encompass the characteristic service life of radiation-cooled building ceramics, preferably t is 1 to 7 days.

[0044] The time interval for collecting intracavitary temperature data is 10 min to 30 min.

[0045] Step 5: After completing the test in Step 4 (Qair-t), the sample chamber and control chamber should be placed in an indoor environment. Simultaneously, the radiation-cooled building ceramic and reference sample should be removed and left for 6 to 24 hours. Once the sample chamber, control chamber, test sample, and reference sample have reached thermal equilibrium, the test sample and reference sample should be installed on the upper surface of the sample chamber and control chamber, respectively. Simultaneously, the target temperature Tcool should be set, triggering the temperature sensors, cooling coils, and cooling fans in the sample and control chambers. Based on the measured air temperature and the target temperature Tcool within the chambers, the cooling coil power should be dynamically adjusted via PID control to ensure consistency between the air temperature and the target temperature. The operating voltage and current of the cooling coil should be recorded simultaneously. The principle of the cooling coil PID control system can be found in [reference needed]. Figure 5 That is, when the internal temperature of the cavity is greater than the preset target temperature, the cooling element starts; conversely, when the internal temperature of the cavity is less than the preset target temperature, the cooling element stops, thereby achieving consistency between the internal temperature of the cavity and the preset target temperature. After the test platform has been running for a period of time (test period t), the energy saving of radiation-cooled building ceramics can be calculated using the following formula (7). ): (7) In equation (7): Energy savings in refrigeration of radiative-cooled building ceramics (J / m²) 2 ); U 对照腔 , U 样品腔These are the operating voltages (V) of the cooling plates in the control chamber and the sample chamber, respectively. I 对照腔 , I 样品腔 These are the operating currents (A) of the cooling plates in the control chamber and the sample chamber, respectively. t The sampling time (in seconds) for the operating voltage and current of the cooling chips in the sample chamber and control chamber is t, which is the test period, ranging from 1 to 7 days; A is the surface area of ​​the test sample (m²). 2 ).

[0046] T cool It should be based on the average ambient temperature ( T atmosphere The ambient average temperature was determined by measuring the temperature and humidity meter installed outside the cavity. T cool Should be compared T atmosphere 5 to 10 degrees Celsius lower.

[0047] U 对照腔 , U 样品腔 , I 对照腔 , I 样品腔 The test data acquisition time interval is 1 to 10 minutes.

[0048] Furthermore, the effective cooling power of radiative cooling building ceramics can be calculated using the following formula (8). ): (8) In equation (8): Effective cooling power (W / m²) for radiative cooling building ceramics 2 ), COP The coefficient of performance (dimensionless) of the thermoelectric cooler.

[0049] In step 1, the reference sample is a common commercial building ceramic product without radiative cooling, serving as a replacement for radiative-cooled building ceramics; and the test sample and the reference sample have the same surface area. The sample chamber and the control chamber have completely identical geometric dimensions and materials.

[0050] The foam box is placed on an adjustable shelf (0 ~ 45°) to receive full sunlight, and the entire box is wrapped with tin foil to reduce the impact of ambient heat on the test platform.

[0051] The temperature measurement range of the thermometer and hygrometer is -40~70 ℃, and the humidity measurement range is 0~100 %RH; The solar irradiance measurement range of the irradiance meter is 0~2000 W / m 2 ; The purpose of setting up the thermometer, hygrometer, and irradiance meter is to establish the correlation between ambient temperature, ambient humidity, solar irradiance, and the theoretical net radiative cooling power of radiative-cooled building ceramics. The parameter data collected by the thermometer, hygrometer, and irradiance meter are not used in the calculation of radiative cooling service performance.

[0052] The temperature sensor is any one of platinum resistance thermometer, copper resistance thermometer, or nickel resistance thermometer, with a temperature measurement range of -50 to 450 ℃ and an accuracy of ±0.1 ℃.

[0053] The cooling element is a semiconductor cooling element (thermoelectric cooling element) with a rated power (cooling capacity) of 50~250 W, a coefficient of performance (COP) of 0.3~0.7, and an operating temperature of 5~50 ℃. The cold end of the cooling element is in direct contact with the air inside the cavity, and a cooling fan is installed inside the cavity to accelerate heat convection between the cold end and the cavity and shorten the thermal equilibrium time of the cavity temperature. The hot end of the cooling element should be placed on the outside of the cavity, and cooled by air dissipation or forced air cooling.

[0054] The cooling chip should be installed in the middle of the cavity. If it is installed above the cavity, the cooling chip will be too close to the test sample, and the cold air generated at the cold end of the cooling chip may affect the test sample. If it is installed below the cavity, too much cold air may accumulate at the bottom of the cavity, resulting in uneven temperature distribution inside the cavity. The cooling fan should be installed close to the cooling chip to maximize heat convection within the cavity.

[0055] Temperature sensors responsible for collecting air temperature data within the cavity must number at least two in each cavity. T 样品腔 =( T 1 +T 2 +T 3 +......+T n ) / n, T 对照腔 =( T 1 +T 2 +T 3 +......+T n ) / n , n The number of temperature sensors. T n For the first nThe temperature measured by each sensor; and the number of temperature sensors in the sample chamber and the control chamber should be the same (all are...). n ).

[0056] The total heat flux sensor is a thin-film type, with an operating temperature range of -180 °C to 200 °C and a measurement range of -200 kW / m. 2 ~ 200 kW / m 2 It can be either HS-10B or HS-34CB.

[0057] The radiative heat flux sensor should be equipped with an optical window to enable control over the spectral wavelength response range, which should be 0.3 ~ 50 μm, with an operating temperature of -180 °C to 200 °C and a measurement range of -200 kW / m. 2 ~ 200 kW / m 2 It can be either TS-10C or TS-34C.

[0058] The infrared thermometer has a temperature measurement range of -50 to 600 ℃ and a field-to-view ratio of 3:1 to 1:1. Since the size of building ceramics is generally 300 mm × 300 mm to 900 mm × 1800 mm, when the field-to-view ratio is too large, the distance between the infrared thermometer and the building ceramic will be too close, which may cause projection on the surface of the building ceramic under actual sunlight, thus affecting the test results. On the other hand, when the field-to-view ratio is too small, the distance between the infrared thermometer and the sample will be too far, resulting in increased error.

[0059] The infrared thermal imager has a temperature measurement range of -40 to 800 ℃ and a focal length of 6 to 8 mm. Similarly, when the focal length is too large, the distance between the infrared thermal imager and the building ceramics will be too close, potentially causing projections onto the ceramic surface under sunlight and affecting the test results. Conversely, a too small field of view will result in the infrared thermal imager being too far from the sample, leading to increased errors.

[0060] The foam box material is any one of polystyrene foam board, polyurethane foam board, or phenolic foam board, and its thermal conductivity should be ≤0.035 W / (m·K). The thickness of the insulation material on the outer wall of the cavity should be ≥200 mm.

[0061] The geometric dimensions of the building ceramic sample ( L The dimensions of the foam box should be no less than 300 mm × 300 mm, and the geometric dimensions of the foam box should be no less than 700 mm × 700 mm × 500 mm.

[0062] At least two temperature sensors should be present in the cavity to ensure temperature uniformity within the cavity. They should be mounted on two opposite surfaces, one at a higher height and the other at a lower height. The distance from the top and bottom surfaces should be ≥100 mm, and the height difference between the two sensors should be ≥150 mm. The cavity structure and temperature sensor arrangement of the sample and control cavities can be referenced. Figure 3 .

[0063] The thermal radiation power emitted by the surface of radiative-cooled building ceramics is a function of the surface temperature of the cooler and the emission spectrum, and can be expressed as: P rad (T) = dΩ d =β 8~13 σ T 4 (9) Where: Ω is the solid angle. The polar angle between the normal to the surface of the radiative cooler and the direction of the solid angle; T is the absolute temperature of the surface of the radiative cooler. It is the emissivity of the surface of the radiative cooler, and its value varies with the surface angle and wavelength; It is the spectral radiation intensity of a blackbody at temperature T. It can be calculated using Planck's law of radiation: = (10) In equation (10): h is Planck's constant; k is Boltzmann's constant; c is the speed of light.

[0064] Substituting equation (10) into equation (9), we get: β 8~13 = (11).

[0065] Given that the extreme temperature range in China is approximately -50 ℃ to 60 ℃, the values ​​of β8~13 at different temperatures (223.15 ~ 333.15 K) were calculated using equation (11), and curves were fitted to them, as shown below. Figure 6 As shown. For Figure 6 Curve fitting analysis was performed on the calculated values ​​of β8~13 to obtain... Its coefficient of determination R² is as high as 0.9999, indicating that the curve has a high goodness of fit. Therefore, the simplified calculation of β8~13 can be achieved by using this fitting relationship.

[0066] The radiometer must be any one of RS-RA-AL, RS-GH-N01-AL, or RS-TBQ-AL, and its irradiance testing range must meet the requirement of 0 ~ 2000 W / m². 2 Place it under direct sunlight, ensuring there are no obstructions above, to accurately obtain data on how solar irradiance changes over time.

[0067] The thermometer and hygrometer can be any of the following types: capacitive, resistive, or optical. Its temperature testing range must be -30 to 120 °C. It should be placed at the same height as the building being tested, at a distance of ≥300 mm, to ensure that its operation does not affect the performance of the building's ceramic surface, in order to obtain data on changes in ambient temperature and humidity over time.

[0068] The infrared thermometer can be either a monochrome infrared thermometer or a dual-color infrared thermometer, and its temperature testing range must be -30 to 100 ℃. Based on the focal length of the thermometer lens and the actual size of the ceramic building to be tested, place it at the corresponding position to obtain data on the average temperature change of the ceramic's upper surface over time. The distance should be ≥500 mm to prevent projection on the ceramic surface from affecting the test results.

[0069] The infrared thermal imager can be either MV-GF120 or MV-GF480. Based on the focal length of the thermal imager lens and the actual size of the building ceramic to be tested, place it in the corresponding position to obtain data on the temperature distribution of the upper surface of the ceramic and the temperature change of the user-selected area over time. The distance should be ≥500 mm to prevent the projection on the surface of the building ceramic from affecting the test results.

[0070] All devices use the RS485 communication protocol. The data acquisition time interval should be 1 to 30 minutes. If the time interval is too short, the instrument will not be able to acquire data normally and may exceed the instrument's accuracy range. If the time interval is too long, fewer data points will be acquired, leading to increased errors and reduced data accuracy.

[0071] The main testing mechanism / principle of the radiation cooling service performance of building ceramics involved in this invention is as follows: At the energy quantification level, the core service performance of radiation-cooled building ceramics lies in their ability to radiate heat to the outside through an 8-13 μm atmospheric window and reflect heat back to the outside through a 0.3-2.5 μm window. The cooling effect is essentially the energy difference between the material's own radiative heat exchange and the environmental heat input (such as solar radiation and air convection). This invention uses an active cooling temperature control system to precisely lock the internal temperature of the sample chamber and the control chamber to the same target value, replacing traditional single-point testing with overall chamber energy balance. This avoids local errors caused by the poor thermal conductivity, large size (thickness), poor surface uniformity, and testing location of building ceramics. At this point, the energy balance between the two chambers must be dynamically achieved: the control chamber only exchanges heat with the outside through ordinary ceramic, and the electrical power required to maintain the target temperature is entirely used to offset the environmental heat input; while the sample chamber, due to the radiative cooling effect of the ceramic sample under test, can reduce the environmental heat input through active heat dissipation, thus requiring less electrical power to maintain the same temperature. According to the law of conservation of energy, the difference in power consumption between the two chambers is the amount of energy saved by the ceramic under test through radiative heat exchange. This process completely eliminates interference from ambient temperature fluctuations, differences in heat conduction, etc., and achieves direct and accurate quantification of cooling performance by using lateral relative comparison. Furthermore, based on the performance coefficient of the cooling element, the effective cooling power of the radiative cooling building ceramic can be obtained.

[0072] Meanwhile, without activating the cooling element, the effective air cooling capacity of radiation-cooled building ceramics can be calculated based on heat using temperature difference, air specific heat capacity, and mass. Furthermore, the theoretical cooling power of radiation-cooled building ceramics can be directly calculated using the material's surface temperature, solar irradiance, material reflectivity, material emissivity, total heat flux, and net radiative heat flux on the ceramic surface. Regarding the deep integration of multi-physics field monitoring and characterization logic in the testing system, an infrared thermometer is used to capture macroscopic temperature data based on Planck's blackbody radiation law. Combined with dynamic dot matrix temperature measurement technology, a thermal imager's focal plane array detector performs full-area dot matrix acquisition of the sample surface. This not only generates a two-dimensional temperature field map but also outputs a dataset including the average surface temperature, user-selected area temperature, the difference between the highest and lowest temperatures, and a surface temperature distribution map. When analyzing temperature gradients based on Boltzmann's law, it can accurately identify local heat dissipation anomalies and directly analyze the surface temperature uniformity through temperature standard deviation. The temperature sensor, based on the linear change characteristic of metal resistance with temperature, monitors the internal temperature of the cavity in real time, ensuring that the temperature difference between the two cavities meets the test accuracy requirements, and can output a dataset of the internal temperature of the cavity changing over time; the thermo-hygrometer and the irradiance meter collect the external ambient temperature, water vapor content and solar irradiance respectively, and simultaneously output the data of the corresponding parameters changing over time.

[0073] This invention provides a method for monitoring and evaluating the radiative cooling performance of building ceramics, which has the following beneficial effects: 1. By introducing a total heat flux sensor and a radiative heat flux sensor, the sum of heat conduction and heat convection power between radiatively cooled building ceramics and the service environment can be accurately tested, thereby enabling precise calculation of the theoretical net radiative cooling power of building ceramics and significantly improving the quantitative testing accuracy of the intrinsic cooling performance of building ceramic materials. 2. By employing dynamic dot matrix temperature measurement and infrared thermography, real-time zoned measurement and recording of the global surface temperature of radiation-cooled building ceramics are achieved. A surface temperature distribution map can be output, and the heat dissipation uniformity can be quantitatively evaluated by calculating the temperature standard deviation. Simultaneously, this method can effectively identify localized heat dissipation anomalies caused by microscopic defects or uneven decoration, overcoming the shortcomings of traditional single-point temperature measurement in comprehensively reflecting the heat dissipation characteristics of large-sized products. 3. Based on the "electric power difference integration method" and the overall energy balance of the cavity, by controlling the balance of the target air temperature values ​​in the sample cavity and the control cavity, and by recording the electric power of the cooling elements in both cavities in real time, accurate testing of effective air cooling capacity, cooling energy savings, and effective cooling power was achieved. This method eliminates local errors caused by the low thermal conductivity, large size, and surface inhomogeneity of the samples, providing reliable quantitative indicators for evaluating the energy-saving and carbon-reducing effects of radiation-cooled building ceramics.

[0074] Example 1 A method for monitoring and evaluating the service performance of building ceramics under radiative cooling, with the specific test steps as follows.

[0075] 1. Prepare a 400 mm × 400 mm × 9 mm radiative cooling building ceramic sample and a conventional building ceramic sample of the same size (antique glaze, white solid color brick, gloss level 8°). Use a spectrophotometer and a Fourier transform infrared spectrometer to test their reflectance and emissivity, respectively. According to JG / T 235-2014 "Reflective Thermal Insulation Coatings for Buildings", the solar reflectance of the radiative cooling building ceramic sample is 94.52%, while that of the conventional building ceramic sample is 81.14%. According to T / CECS 10378-2024 "Radiative Cooling Coatings for Buildings", the atmospheric window emissivity of the radiative cooling building ceramic sample is 93.61%, while that of the conventional building ceramic sample is 87.11%.

[0076] 2. Prepare two 700 mm × 700 mm × 700 mm polystyrene foam boxes with a thermal conductivity of 0.033 W / (m·K) to serve as the sample chamber and control chamber, respectively. Figure 7 (As shown). A hole is cut inside the foam box to ensure the outer wall thickness of the cavity is 200 mm, and the internal cavity size is 300 mm × 300 mm × 500 mm, i.e., a volume of 0.045 m³. 3The foam boxes were wrapped inside and out with tin foil to reduce the impact of ambient heat on the testing platform (enhancing sunlight reflection and reducing solar radiation heating of the experimental chamber). Radiation-cooled building ceramic samples (400 mm × 400 mm × 9 mm) and conventional building ceramic samples were placed on top of two cubic foam boxes, respectively. The foam boxes were placed on a 30° stainless steel shelf. A thermometer / hygrometer (Lanyu Environmental Protection GQ-DR600-W, a capacitive thermometer with a temperature testing range of -40 ~ 70 ℃) was then installed and placed at the same height as the building ceramic sample to be tested, at a distance of 400 mm. An irradiance meter (Jianda Renke RS-TBQ-AL, with a solar irradiance testing range of 0 ~ 2000 W / m²) was also installed. 2 The following instruments were used: an infrared thermometer (Optics CTLT02, a monochrome infrared thermometer with a temperature measurement range of -50 ~ 600 ℃, a field-to-view ratio of 2:1, placed at a distance of 700 mm from the ceramic building to be tested); an infrared thermal imager (Medvision MV-GF120, with a temperature measurement range of -20 ~ 400 ℃, a focal length of 7 mm, placed at a distance of 700 mm from the ceramic building to be tested); and an HS-34CB ultra-thin heat flux density sensor (operating temperature of -180 ~ 200 ℃, measuring range of -200 ~ 200 kW / m). 2 TS-34C radiative heat flux density sensor (operating temperature -180 ~ 200℃, measuring range -200 ~ 200 kW / m³) 2 Inside the cavity, two PT100 resistance temperature sensors (platinum resistance thermometers, WZP-035, temperature range -50 ~ 450 ℃, accuracy ±0.1 ℃) are installed on opposite surfaces of the cavity's inner wall, with one sensor at a height 100 mm from the top and the other at a height 100 mm from the bottom, a height difference of 300 mm. One thermoelectric cooler (Touglesy 12706, a semiconductor cooler with a rated power of 100 W, operating temperature of 5 ~ 50 ℃, and a coefficient of performance (COP) of 0.5) is also installed. All devices are connected via LabVIEW software using the RS485 protocol.

[0077] 3: Trigger the irradiance meter and thermo-hygrometer to simultaneously collect solar irradiance, ambient temperature, and humidity; and trigger the infrared thermometer to measure the surface temperature of the radiation-cooled ceramic; then trigger the total heat flux sensor and the radiative heat flux sensor to measure the total heat flux and net radiative heat flux of the working surface (upper surface) of the radiation-cooled building ceramic. Calculate the theoretical net radiative cooling power of the radiation-cooled building ceramic using equations (1) to (4). Measure the ambient temperature T at this time using the thermo-hygrometer. atm= 308K. The average temperature of the sample's upper surface measured by an infrared thermometer is T = 305 K. According to Calculation yields β 8~13 = 0.3252, then according to equation (2), we can obtain P rad = 149.4 W / m 2 According to equation (3), we can obtain P solar = 850×(1-0.9452) = 46.6 W / m 2 The total heat flux is measured by the total heat flux sensor. Q = 65.3 W / m 2 Radiant heat flow sensor measures radiant heat flow Q r = 28.1 W / m 2 Then, according to equation (4), we can obtain P cond+conv = 65.3 - 28.1 = 37.2 W / m 2 Furthermore, the theoretical net radiative cooling power of radiative-cooled building ceramics can be calculated using equation (1). P net = 65.6 W / m 2 .

[0078] To establish the correlation between solar irradiance, ambient temperature, ambient humidity and the theoretical net radiative cooling power of radiative-cooled building ceramics, LabVIEW can be used to connect an irradiance meter, a hygrometer, and an infrared thermometer in series, calculate the theoretical net radiative cooling power, and collect and store the data.

[0079] 4. Remove the total heat flow and radiative heat flow sensors from the upper surface of the radiation-cooled building ceramic sample. Using the infrared thermal imager control module in LabVIEW, the upper surface of the sample was divided into 16 temperature zones (each zone 100 mm × 100 mm), and the temperatures of each zone were collected: 31.8 ℃, 31.9 ℃, 32.0 ℃, 31.7 ℃, 32.1 ℃, 32.0 ℃, 31.9 ℃, 31.8 ℃, 32.0 ℃, 32.1 ℃, 32.2 ℃, 32.0 ℃, 31.9 ℃, 31.8 ℃, 31.9 ℃, 32.0 ℃. The average value was 31.95 ℃. Substituting this into formula (5) yielded the standard deviation of the temperature distribution. = 0.12 ℃, indicating that the heat dissipation uniformity of the radiation-cooled ceramic surface is excellent.

[0080] 5: Install two PT100 resistance temperature sensors (e.g., ...) on the inner walls of both the sample chamber and the control chamber. Figure 3 As shown), the average value of the two temperature sensors is the average temperature of the sample chamber and the control chamber. T 样品腔 , T 对照腔 Simultaneously, the cooling fans in the sample chamber and control chamber are activated to ensure an even distribution of air temperature within the chambers. Furthermore, an RS485 temperature acquisition transmitter is used to monitor and record the average air temperature in the sample chamber and control chamber in real time. The temperature acquisition frequency is once every 10 minutes, and the monitoring and recording period is 1 day (from 12:00 noon to 12:00 noon the next day). Based on the chamber volume and sample surface area of ​​the sample chamber and control chamber, the effective air cooling capacity of the radiation-cooled building ceramics can be calculated using equation (6). Q air-t =1008×1.205×0.045× T 对照腔 - T 样品腔 dt / 86400 / 0.16≈1.13×10 3 J / m 2 .

[0081] 6. After completing step 5, move both the sample chamber and the control chamber to an indoor space and allow them to stand for 6 hours to reach thermal equilibrium (the temperature inside the chamber and the surface temperature of the sample should be the same as the indoor air temperature). Then, move the sample chamber and the control chamber outdoors and place them in the service environment of radiation-cooled building ceramics; set the target temperature. T cool = 28 ℃ (7 ℃ lower than the average service environment temperature of 35 ℃), and triggered the PID control of the cooling chip and the cooling fan, so that the temperature inside the sample chamber and the control chamber was stabilized at 28 ℃ through the dynamic operation of the cooling chip. Continuous testing was conducted for 1 day (t = 86400 s), and the working voltage and current of the cooling chip in the sample chamber and the control chamber were recorded in real time using the RS485 analog output module and the LabVIEW recording program (recording time interval was 1 min). The energy saving of cooling can be calculated using equation (7). = U 对照腔 I 对照腔 - U 样品腔 I 样品腔 )dt / 0.16≈1.17×10 7 J / m 2 The coefficient of performance (COP) of the cooling element is 0.5. Substituting this into formula (8) yields the effective cooling power of the radiative cooling building ceramics. = 0.5 × 1.17 × 107 / 86400≈67.5 W / m 2 .

[0082] Example 2 A method for monitoring and evaluating the service performance of building ceramics under radiative cooling, with the specific test steps as follows.

[0083] 1. Prepare a 600 mm × 600 mm × 9 mm radiative cooling building ceramic sample and a conventional building ceramic sample of the same size (satin glaze, light-colored stone-textured tile, gloss level 30°). Use a spectrophotometer and a Fourier transform infrared spectrometer to test their reflectance and emissivity, respectively. According to JG / T 235-2014 "Reflective Thermal Insulation Coatings for Buildings", the solar reflectance of the radiative cooling building ceramic sample is 94.18%, while that of the conventional building ceramic sample is 80.28%. According to T / CECS 10378-2024 "Radiative Cooling Coatings for Buildings", the atmospheric window emissivity of the radiative cooling building ceramic sample is 93.55%, while that of the conventional building ceramic sample is 86.59%.

[0084] 2. Prepare two 900 mm × 900 mm × 700 mm polystyrene foam boxes with a thermal conductivity of 0.033 W / (m·K) to serve as the sample chamber and control chamber, respectively. Figure 7 (As shown). A hole is cut inside the foam box to ensure the outer wall thickness of the cavity is 200 mm, and the internal cavity size is 500 mm × 500 mm × 500 mm, i.e., a volume of 0.125 m³. 3 The foam boxes were wrapped inside and out with tin foil to reduce the impact of ambient heat on the testing platform (enhancing sunlight reflection and reducing solar radiation heating of the experimental chamber). Radiation-cooled building ceramic samples (600 mm × 600 mm × 9 mm) and conventional building ceramic samples were placed on top of two cubic foam boxes, respectively. The foam boxes were placed on a 30° stainless steel shelf. A thermometer / hygrometer (Lanyu Environmental Protection GQ-DR600-W, a capacitive thermometer with a temperature testing range of -40 ~ 70 ℃) was then installed and placed at the same height as the building ceramic sample to be tested, at a distance of 400 mm. An irradiance meter (Jianda Renke RS-TBQ-AL, with a solar irradiance testing range of 0 ~ 2000 W / m²) was also installed. 2The following instruments were used: an infrared thermometer (Optics CTLT02, a monochrome infrared thermometer with a temperature measurement range of -50 ~ 600 ℃, a field-to-view ratio of 2:1, placed at a distance of 700 mm from the ceramic building to be tested); an infrared thermal imager (Medvision MV-GF120, with a temperature measurement range of -20 ~ 400 ℃, a focal length of 7mm, placed at a distance of 700 mm from the ceramic building to be tested); and an HS-34CB ultra-thin heat flux density sensor (operating temperature of -180 ~ 200℃, measuring range of -200 ~ 200 kW / m). 2 TS-34C radiative heat flux density sensor (operating temperature -180~200℃, measuring range -200~200 kW / m³) 2 Inside the cavity, two PT100 resistance temperature sensors (WZP-035, platinum resistance thermometers, temperature range -50 ~ 450 ℃, accuracy ±0.1 ℃) are installed on opposite surfaces of the cavity's inner wall, with one sensor at a height 100 mm from the top and the other at a height 100 mm from the bottom, a height difference of 300 mm. One thermoelectric cooler (Touglesy 12706, a semiconductor cooler with a rated power of 100 W, operating temperature of 5 ~ 50 ℃, and a coefficient of performance (COP) of 0.5) is also installed. All devices are connected via LabVIEW software using the RS485 protocol.

[0085] 3: Trigger the irradiance meter and thermo-hygrometer to simultaneously collect solar irradiance, ambient temperature, and humidity; and trigger the infrared thermometer to measure the surface temperature of the radiation-cooled ceramic; then trigger the total heat flux sensor and the radiative heat flux sensor to measure the total heat flux and net radiative heat flux of the working surface (upper surface) of the radiation-cooled building ceramic. Calculate the theoretical net radiative cooling power of the radiation-cooled building ceramic using equations (1) to (4). Measure the ambient temperature T at this time using the thermo-hygrometer. atm =308K. The average temperature of the sample's upper surface measured by an infrared thermometer is T = 304 K. According to Calculation yields β 8~13 = 0.3246, then according to equation (2), we can obtain P rad = 147.1 W / m 2 According to equation (3), we can obtain P solar = 860×(1-0.9418) = 50.1 W / m 2 The total heat flux is measured by the total heat flux sensor. Q = 64.4 W / m 2 Radiant heat flow sensor measures radiant heat flowQ r = 26.7 W / m 2 Then, according to equation (4), we can obtain P cond+conv = 64.4 - 26.7 = 37.7 W / m 2 Furthermore, the theoretical net radiative cooling power of radiative-cooled building ceramics can be calculated using equation (1). P net = 59.3 W / m 2 .

[0086] To establish the correlation between solar irradiance, ambient temperature, ambient humidity and the theoretical net radiative cooling power of radiative-cooled building ceramics, LabVIEW can be used to connect an irradiance meter, a hygrometer, and an infrared thermometer in series, calculate the theoretical net radiative cooling power, and collect and store the data.

[0087] 4. Remove the total heat flow and radiative heat flow sensors from the upper surface of the radiation-cooled building ceramic sample. Using the infrared thermal imager control module in LabVIEW, the upper surface of the sample was divided into 16 temperature zones (each zone 150 mm × 150 mm), and the temperatures of each zone were collected: 30.7 ℃, 30.8 ℃, 30.8 ℃, 30.6 ℃, 30.9 ℃, 30.8 ℃, 30.8 ℃, 30.7 ℃, 30.9 ℃, 30.9 ℃, 31.0 ℃, 30.8 ℃, 30.7 ℃, 30.7 ℃, 30.8 ℃, 30.9 ℃. The average value was 30.8 ℃. Substituting this into formula (5) yielded the standard deviation of the temperature distribution. = 0.10 ℃, indicating that the heat dissipation uniformity of the radiation-cooled ceramic surface is excellent.

[0088] 5: Install two PT100 resistance temperature sensors (e.g., ...) on the inner walls of both the sample chamber and the control chamber. Figure 3 As shown), the average value of the two temperature sensors is the average temperature of the sample chamber and the control chamber. T 样品腔 , T 对照腔 Simultaneously, the cooling fans in the sample chamber and control chamber are activated to ensure an even distribution of air temperature within the chambers. Furthermore, an RS485 temperature acquisition transmitter is used to monitor and record the average air temperature in the sample chamber and control chamber in real time. The temperature acquisition frequency is once every 20 minutes, and the monitoring and recording period is 4 days (from 12:00 noon to 12:00 noon on the fourth day). Based on the chamber volume and sample surface area of ​​the sample chamber and control chamber, the effective air cooling capacity of the radiation-cooled building ceramics can be calculated using equation (6). Q air-t=1008×1.205×0.045× T 对照腔 - T 样品腔 dt / 345600 / 0.16≈1.14×10 3 J / m 2 .

[0089] 6. After completing step 5, move both the sample chamber and the control chamber to an indoor space and allow them to stand for 12 hours to reach thermal equilibrium (the temperature inside the chamber and the surface temperature of the sample should be the same as the indoor air temperature). Then, move the sample chamber and the control chamber outdoors and place them in the service environment of radiation-cooled building ceramics; set the target temperature. T cool = 28 ℃ (average ambient temperature 35 ℃, low 7 ℃), and triggered the PID control of the cooling chip and the cooling fan, so that the temperature inside the sample chamber and the control chamber was stabilized at 28 ℃ through the dynamic operation of the cooling chip. Continuous testing was conducted for 4 days (t = 345600 s). The working voltage and current of the cooling chip in the sample chamber and the control chamber were recorded in real time using the RS485 analog output module and the LabVIEW recording program (recording time interval was 5 min). The energy saving of cooling can be calculated using equation (7). = U 对照腔 I 对照腔 - U 样品腔 I 样品腔 )dt / 0.16≈4.54×10 7 J / m 2 The coefficient of performance (COP) of the cooling element is 0.5. Substituting this into formula (8) yields the effective cooling power of the radiative cooling building ceramics. = 0.5 × 4.54 × 10 7 / 345600≈65.7 W / m 2 .

[0090] Example 3 A method for monitoring and evaluating the service performance of building ceramics under radiative cooling, with the specific test steps as follows.

[0091] 1. Prepare an 800 mm × 800 mm × 9 mm radiative cooling building ceramic sample and an identically sized conventional building ceramic sample (antique glaze, light-colored stone-textured tile, gloss level 12°). Measure their reflectance and emissivity using a spectrophotometer and a Fourier transform infrared spectrometer, respectively. According to JG / T 235-2014 "Reflective Thermal Insulation Coatings for Buildings", the solar reflectance of the radiative cooling building ceramic sample is 94.92%, while that of the conventional building ceramic sample is 81.55%. According to T / CECS 10378-2024 "Radiative Cooling Coatings for Buildings", the atmospheric window emissivity of the radiative cooling building ceramic sample is 93.75%, while that of the conventional building ceramic sample is 87.32%.

[0092] 2: Prepare two 1100 mm × 1100 mm × 700 mm polystyrene foam boxes with a thermal conductivity of 0.033 W / (m·K) to serve as the sample chamber and control chamber, respectively. Figure 7 (As shown). A hole is cut inside the foam box to ensure the outer wall thickness of the cavity is 200 mm, and the internal cavity size is 700 mm × 700 mm × 500 mm, i.e., a volume of 0.245 m³. 3 The foam boxes were wrapped inside and out with tin foil to reduce the impact of ambient heat on the testing platform (enhancing sunlight reflection and reducing solar radiation heating of the experimental chamber). Radiation-cooled building ceramic samples (800 mm × 800 × 9 mm) and conventional building ceramic samples were placed on top of two cubic foam boxes, respectively. The foam boxes were placed on a 30° stainless steel shelf. A thermometer / hygrometer (Lanyu Environmental Protection GQ-DR600-W, a capacitive thermometer with a temperature testing range of -40 ~ 70 ℃) was then installed and placed at the same height as the building ceramic sample, at a distance of 400 mm. An irradiance meter (Jianda Renke RS-TBQ-AL, with a solar irradiance testing range of 0 ~ 2000 W / m²) was also installed. 2 The following instruments were used: an infrared thermometer (Optics CTLT02, a monochrome infrared thermometer with a temperature measurement range of -50 ~ 600 ℃, a field-to-view ratio of 2:1, placed at a distance of 700mm from the ceramic building to be tested); an infrared thermal imager (Medvision MV-GF120, with a temperature measurement range of -20 ~ 400 ℃, a focal length of 7 mm, placed at a distance of 700mm from the ceramic building to be tested); and an HS-34CB ultra-thin heat flux density sensor (operating temperature of -180 ~ 200℃, measuring range of -200 ~ 200 kW / m³). 2 TS-34C radiative heat flux density sensor (operating temperature -180 ~ 200℃, measuring range -200 ~ 200 kW / m³)2 Inside the cavity, two PT100 resistance temperature sensors (WZP-035, platinum resistance thermometers, temperature range -50 ~ 450 ℃, accuracy ±0.1 ℃) are installed on opposite surfaces of the cavity's inner wall, with one sensor at a height 100 mm from the top and the other at a height 100 mm from the bottom, a height difference of 300 mm. One thermoelectric cooler (Touglesy 12706, a semiconductor cooler with a rated power of 100 W, operating temperature of 5 ~ 50 ℃, and a coefficient of performance (COP) of 0.5) is also installed. All devices are connected via LabVIEW software using the RS485 protocol.

[0093] 3: Trigger the irradiance meter and thermo-hygrometer to simultaneously collect solar irradiance, ambient temperature, and humidity; and trigger the infrared thermometer to measure the surface temperature of the radiation-cooled ceramic; then trigger the total heat flux sensor and the radiative heat flux sensor to measure the total heat flux and net radiative heat flux of the working surface (upper surface) of the radiation-cooled building ceramic. Calculate the theoretical net radiative cooling power of the radiation-cooled building ceramic using equations (1) to (4). Measure the ambient temperature T at this time using the thermo-hygrometer. atm = 306K. The average temperature of the sample's upper surface measured by an infrared thermometer is T = 303 K. According to Calculation yields β 8~13 = 0.3239, then according to formula (2), we can obtain P rad = 145.1 W / m 2 According to equation (3), we can obtain P solar = 840×(1-0.9492) = 42.7 W / m 2 The total heat flux is measured by the total heat flux sensor. Q = 62.1 W / m 2 Radiant heat flow sensor measures radiant heat flow Q r = 25.8 W / m 2 Then, according to equation (4), we can obtain P cond+conv = 62.1 - 25.8 = 36.3 W / m 2 Furthermore, the theoretical net radiative cooling power of radiative-cooled building ceramics can be calculated using equation (1). P net = 66.1 W / m 2 .

[0094] To establish the correlation between solar irradiance, ambient temperature, ambient humidity and the theoretical net radiative cooling power of radiative-cooled building ceramics, LabVIEW can be used to connect an irradiance meter, a hygrometer, and an infrared thermometer in series, calculate the theoretical net radiative cooling power, and collect and store the data.

[0095] 4. Remove the total heat flow and radiative heat flow sensors from the upper surface of the radiation-cooled building ceramic sample. Using the infrared thermal imager control module in LabVIEW, the upper surface of the sample was divided into 16 temperature zones (each zone 200 mm × 200 mm), and the temperatures of each zone were collected: 30.0 ℃, 30.1 ℃, 30.1 ℃, 29.9 ℃, 30.2 ℃, 30.1 ℃, 30.0 ℃, 30.0 ℃, 30.2 ℃, 30.2 ℃, 30.3 ℃, 30.1 ℃, 30.0 ℃, 30.0 ℃, 30.1 ℃, 30.2 ℃. The average value was 30.1 ℃. Substituting this into formula (5) yielded the standard deviation of the temperature distribution. = 0.10 ℃, indicating that the heat dissipation uniformity of the radiation-cooled ceramic surface is excellent.

[0096] 5: Install two PT100 resistance temperature sensors (e.g., ...) on the inner walls of both the sample chamber and the control chamber. Figure 3 As shown), the average value of the two temperature sensors is the average temperature of the sample chamber and the control chamber. T 样品腔 , T 对照腔 Simultaneously, the cooling fans in the sample chamber and control chamber are activated to ensure an even distribution of air temperature within the chambers. Furthermore, an RS485 temperature acquisition transmitter is used to monitor and record the average air temperature in the sample chamber and control chamber in real time. The temperature acquisition frequency is once every 30 minutes, and the monitoring and recording period is 7 days (from 12:00 noon on the seventh day to 12:00 noon on the seventh day). Based on the chamber volume and sample surface area of ​​the sample chamber and control chamber, the effective air cooling capacity of the radiation-cooled building ceramics can be calculated using equation (6). Q air-t =1008×1.205×0.045× T 对照腔 - T 样品腔 dt / 604800 / 0.16≈1.26×10 3 J / m 2 .

[0097] 6. After completing step 5, move both the sample chamber and the control chamber to an indoor space and allow them to stand for 24 hours to reach thermal equilibrium (the temperature inside the chamber and the surface temperature of the sample should be the same as the indoor air temperature). Then, move the sample chamber and the control chamber outdoors and place them in the service environment of radiation-cooled building ceramics; set the target temperature. T cool = 26 ℃ (average ambient temperature 33 ℃, low 7 ℃), and triggered the PID control of the cooling chip and the cooling fan, so that the temperature inside the sample chamber and the control chamber was stabilized at 26 ℃ through the dynamic operation of the cooling chip. Continuous testing was conducted for 7 days (t = 604800 s). The working voltage and current of the cooling chip in the sample chamber and the control chamber were recorded in real time using the RS485 analog output module and the LabVIEW recording program (recording time interval was 10 min). The energy saving of cooling can be calculated using equation (7). = U 对照腔 I 对照腔 - U 样品腔 I 样品腔 )dt / 0.16≈8.48×10 7 J / m 2 The coefficient of performance (COP) of the cooling element is 0.5. Substituting this into formula (8) yields the effective cooling power of the radiative cooling building ceramics. = 0.5 × 8.48 × 10 7 / 604800≈70.1 W / m 2 .

[0098] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for monitoring and evaluating the service performance of building ceramics under radiative cooling, characterized in that, include: Prepare a sample chamber and a control chamber, wherein both the sample chamber and the control chamber are insulated cavities with cavities. Temperature sensors, cooling chips and cooling fans are installed inside the sample chamber and the control chamber, respectively. Infrared thermometers, infrared thermal imagers, thermo-hygrometers and irradiance meters are installed outside the cavities. The geometric dimensions and materials of the sample chamber and the control chamber are completely identical. The sample chamber and the control chamber are equipped with the same number of temperature sensors, and each has no less than two. The average value of the temperature measured by each temperature sensor in the sample chamber and the control chamber is taken as the actual air temperature of the corresponding cavity. A radiation-cooled building ceramic sample is placed on top of the sample chamber, and a reference sample is placed on top of the control chamber, wherein the reference sample is a conventional building ceramic, and the radiation-cooled building ceramic sample and the reference sample have the same surface area. A total heat flux sensor and a radiative heat flux sensor are installed on the upper surface of the radiation-cooled building ceramic sample. The system triggers the irradiance meter and the temperature and humidity meter to synchronously collect solar irradiance, ambient temperature and humidity; it triggers the infrared thermometer and the infrared thermal imager to measure the surface temperature and surface distribution of the radiation-cooled building ceramic sample; and it triggers the total heat flux sensor and the radiative heat flux sensor to measure the total heat flux and net radiative heat flux of the surface of the radiation-cooled building ceramic sample. Based on the surface thermal radiation power, absorbed solar radiation power, and the sum of thermal conduction and convection power between the radiation-cooled building ceramic sample and the surrounding environment, the theoretical net radiation cooling power of the radiation-cooled building ceramic sample is calculated, wherein the sum of thermal conduction and convection power is determined by the difference between the total heat flow and the net radiation heat flow. Triggering the temperature sensors and cooling fans in the sample chamber and the control chamber; Collect and record the temperature curves of the sample chamber and the control chamber during the service cycle; Based on the temperature difference between the sample chamber and the control chamber, the chamber volume, air density, and air specific heat capacity, the effective air cooling capacity of the radiation-cooled building ceramic sample is calculated. After completing the test of the effective air cooling capacity, the sample chamber and the control chamber are placed in an indoor environment, and the radiation-cooled building ceramic sample and the reference sample are removed and left for 6 to 24 hours until the sample chamber, the control chamber, the radiation-cooled building ceramic sample and the reference sample reach thermal equilibrium. Then, the radiation-cooled building ceramic sample and the reference sample are reinstalled on the top of the sample chamber and the control chamber, respectively. A target temperature Tcool is set based on the average ambient temperature measured by the thermometer and hygrometer, and the target temperature Tcool is 5 to 10°C lower than the average ambient temperature. The temperature sensors, cooling chips, and cooling fans in the sample chamber and the control chamber are triggered. Based on the measured air temperature and the target temperature Tcool in the sample chamber and the control chamber, respectively, the power of the corresponding cooling chips is dynamically adjusted by PID control so that the measured air temperature in the sample chamber and the control chamber is consistent with the target temperature Tcool. The working voltage and working current of the cooling chips in the sample chamber and the control chamber are synchronously collected at time intervals of 1 to 10 minutes. Based on the integral of the power difference between the cooling elements in the control chamber and the sample chamber over the test period, the energy saving of the radiation-cooled building ceramic sample is calculated according to the following formula: ； In the formula, Energy savings in radiative cooling of building ceramics; U 对照腔 , U 样品腔 These are the operating voltages of the cooling plates in the control chamber and the sample chamber, respectively. I 对照腔 , I 样品腔 These are the operating currents of the cooling plates in the control chamber and the sample chamber, respectively. t The sampling time for the working voltage and current of the cooling chip in the sample chamber and control chamber is called the test period, which is t = 1 to 7 days. t is converted to seconds in the calculation. A is the surface area of ​​the test sample; Based on the performance coefficient of the cooling element and the energy savings in cooling, the effective cooling power of the radiation-cooled architectural ceramic sample is calculated according to the following formula: ； In the formula: For radiative cooling building ceramics, the effective cooling power, COP This represents the coefficient of performance (COP) of the thermoelectric cooler.

2. The method according to claim 1, characterized in that, Also includes: Remove the total heat flow sensor and the radiative heat flow sensor from the upper surface of the radiation-cooled architectural ceramic sample; Temperature zones were divided on the upper surface of the radiation-cooled building ceramic sample; The infrared thermal imager is triggered to acquire the surface temperature distribution of the radiation-cooled building ceramic sample. The standard deviation of the surface temperature distribution of the radiation-cooled building ceramic sample was calculated to quantitatively characterize the heat dissipation uniformity of the radiation-cooled building ceramic sample.

3. The method according to claim 2, characterized in that, The temperature zone is 100 mm × 100 mm to 200 mm × 200 mm in size, and the number of temperature zones collected for a single radiation-cooled building ceramic sample is not less than 16.

4. The method according to claim 1, characterized in that, The surface thermal radiation power is calculated based on the average temperature of the upper surface of the radiation-cooled architectural ceramic sample, the emissivity of the atmospheric window, and the ratio of the energy radiated by the blackbody in the atmospheric window to the total energy across the entire wavelength range, wherein the ratio is determined by the average temperature according to Planck's radiation law.

5. The method according to claim 1, characterized in that, The insulation cavity is a foam box, and the material of the foam box is polystyrene foam board, polyurethane foam board or phenolic foam board, with a thermal conductivity of not more than 0.035 W / (m·K), and the thickness of the insulation material on the outer wall of the cavity is not less than 200 mm.

6. The method according to claim 1, characterized in that, The sample chamber and the control chamber have the same geometric dimensions and materials, and the outside of the heat-insulating chamber is wrapped with tin foil to reduce the impact of ambient heat on the test.

7. The method according to claim 1, characterized in that, The distance between the infrared thermometer and the infrared thermal imager and the radiation-cooled building ceramic sample shall not be less than 500 mm.

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