A method and system for detecting the photo-thermal conversion efficiency of a photo-thermal conversion material

Abstract

The application provides a photothermal conversion efficiency detection method and system of a photothermal conversion material, and belongs to the technical field of photothermal conversion. The application records incident irradiation intensity by evaporating the photothermal conversion material under the conditions of simulated sunlight irradiation and continuous water supply; continuously collects the reflectance spectrum, light-receiving surface temperature distribution, water supply side temperature, water supply amount, solution mass change, solution temperature and evaporation interface salt concentration to determine the evaporation water loss; determines the salt crystal uncovered state, salt crystal formation state, salt crystal covered state and salt crystal dissolution state according to the reflectance spectrum and evaporation interface salt concentration; determines the target time in the cycle from the salt crystal formation state to the salt crystal dissolution state, and sequentially changes the water supply flow and the incident irradiation intensity; determines the water supply side heat loss, light energy loss caused by the salt crystal coverage and interface evaporation heat consumption, and calculates the photothermal conversion efficiency in the salt crystal uncovered state, which can improve the accuracy and comparability of the photothermal conversion efficiency detection of the photothermal conversion material under high salt conditions.

Description

Technical Field

[0001] This application belongs to the field of photothermal conversion technology, and in particular relates to a method and system for detecting the photothermal conversion efficiency of photothermal conversion materials. Background Technology

[0002] Photothermal conversion materials can absorb solar radiation and convert it into heat energy, thereby driving water evaporation at the gas-liquid interface. Related technologies show promise in fields such as seawater desalination, brackish water treatment, reverse osmosis brine reduction, and zero-discharge evaporation crystallization.

[0003] Existing technologies typically measure the water loss per unit area of ​​illuminated surface within a predetermined time under simulated sunlight conditions, combining incident light conditions and latent heat of vaporization to obtain performance indicators such as evaporation rate or evaporation efficiency. To address salt accumulation during the evaporation process of high-salt water, existing technologies primarily focus on optimizing evaporator structure, material wettability, and water-salt transport conditions to maintain evaporator performance.

[0004] However, during continuous evaporation and crystallization processes in high-salinity concentrated seawater, brackish water, or concentrated brine, salt enrichment and scale deposition can easily cause changes in the evaporation performance of materials over time. Existing testing methods often use evaporation rates or evaporation efficiencies obtained from single or short-term tests as material performance indicators, which are insufficient to fully reflect the actual performance of materials under long-term operation under high-salinity conditions. Therefore, existing technologies suffer from insufficient accuracy in detecting the photothermal conversion efficiency of photothermal conversion materials under high-salinity conditions. Summary of the Invention

[0005] The purpose of this application is to provide a method, system, and electronic device for detecting the photothermal conversion efficiency of photothermal conversion materials, so as to solve the problem of insufficient accuracy in detecting the photothermal conversion efficiency of photothermal conversion materials under high salt conditions in the prior art.

[0006] To address the aforementioned technical problems, in a first aspect, this application provides a method for detecting the photothermal conversion efficiency of a photothermal conversion material, comprising: The photothermal conversion material was placed at the liquid surface of the evaporation unit so that the light-receiving surface was above the liquid surface. Evaporation was carried out under simulated sunlight and continuous water supply, and the incident irradiance was recorded. Continuous collection of detection data, including reflectance spectrum, temperature distribution of the light-receiving surface, water supply side temperature, water supply volume, solution mass change, solution temperature and salt concentration at the evaporation interface, and determination of evaporation water loss based on water supply volume and solution mass change; Based on the continuously collected reflectance spectra and salt concentration at the evaporation interface, the states of salt crystal uncovered, salt crystal formed, salt crystal covered, and salt crystal dissolved were determined. During the cycle from salt crystal formation to salt crystal dissolution, the target time is determined based on the rate of change of salt concentration at the evaporation interface and the reflection spectrum. Starting from the target time, the incident irradiance is kept constant while the water supply flow rate is changed, and then the incident irradiance is changed while the water supply flow rate is kept constant. Data is collected before and after each change. The heat transfer loss on the water supply side is determined based on the temperature distribution of the light-receiving surface before and after the change in water supply flow rate, the temperature on the water supply side, and the amount of water lost through evaporation. The light energy loss caused by salt crystal coverage is determined based on the reflection spectrum before and after the change in incident irradiance intensity. The heat consumption of interfacial evaporation is determined based on the amount of water lost through evaporation, the solution temperature, and the salt concentration at the evaporation interface. During the collection period when the salt crystals are not covered, the photothermal conversion efficiency is calculated based on the incident irradiance, light energy loss, heat transfer loss on the water supply side, and heat consumption from interface evaporation.

[0007] In one feasible implementation, the solution within the evaporation unit is high-salinity concentrated seawater or brackish water; the method further includes: Before the target time, based on the rate of change of salt concentration at the evaporation interface, the change in reflection intensity within the predetermined band, and the change in evaporation water loss, the proportion of change in water supply flow rate and the proportion of change in incident irradiance from the target time are determined. The predetermined band is a band selected from the acquisition range of the reflection spectrum and remains unchanged during a cycle from salt crystal formation to salt crystal dissolution. Starting from the target time, the water supply flow rate is adjusted according to the change ratio of the water supply flow rate, and the incident radiation intensity is adjusted according to the change ratio of the incident radiation intensity.

[0008] In one feasible implementation, the proportion of change in water supply flow rate and the proportion of change in incident irradiance intensity from the target time are determined based on the rate of change of salt concentration at the evaporation interface, the change in reflection intensity within a predetermined wavelength band, and the change in evaporative water loss, including: The rate of change of salt concentration at the evaporation interface, the change of reflection intensity within a predetermined band, and the change of evaporation water loss are compared with their respective preset ranges. If the change in reflection intensity within the predetermined band exceeds the corresponding preset range, and the change in evaporation loss does not exceed the corresponding preset range, then the absolute value of the change ratio of incident irradiance intensity is made greater than the absolute value of the change ratio of water supply flow. If the change in evaporation loss exceeds the corresponding preset range, and the change in reflection intensity within the predetermined band does not exceed the corresponding preset range, then the absolute value of the change in water supply flow rate is made greater than the absolute value of the change in incident radiation intensity. If the rate of change of salt concentration at the evaporation interface exceeds the corresponding preset range, and the changes in reflection intensity and evaporation water loss within the predetermined band do not exceed the corresponding preset range, then the water supply flow rate and incident irradiance are increased simultaneously, so that the change ratio of water supply flow rate and the change ratio of incident irradiance are both positive.

[0009] In one feasible implementation, based on continuously acquired reflectance spectra and salt concentration at the evaporation interface, the states of uncovered salt crystals, salt crystal formation, covered salt crystals, and dissolved salt crystals are determined, including: If, within a continuous acquisition period, the change in reflection intensity of the reflection spectrum within a predetermined band does not exceed the first preset fluctuation threshold, and the change in salt concentration at the evaporation interface does not exceed the second preset fluctuation threshold, then it is determined to be a state where salt crystals are not covered. If the change in salt concentration at the evaporation interface continues to increase, and the change in reflection intensity increases in two or more consecutive acquisition cycles, then it is determined to be a salt crystal formation state. If the change in reflection intensity remains within the third preset fluctuation range within a preset time period, it is determined to be a salt crystal coverage state; If the change in salt concentration at the evaporation interface decreases, and the difference between the change in reflection intensity and the change in reflection intensity under the uncovered salt crystal state decreases, then it is determined to be a salt crystal dissolved state.

[0010] In one feasible implementation, the target time is determined based on the reflectance spectrum and the rate of change of salt concentration at the evaporation interface, including: During the cycle from salt crystal formation state to salt crystal dissolution state, the change in reflection intensity of the reflection spectrum within a predetermined band is determined; If the rate of change of salt concentration at the evaporation interface continues to increase, and the change in reflection intensity increases in two or more consecutive acquisition cycles, then the acquisition time at which the aforementioned changes are simultaneously met for the first time will be determined as the target time.

[0011] In one feasible implementation, the heat transfer loss on the water supply side is determined based on the temperature distribution of the light-receiving surface before and after the change in water supply flow rate, the water supply side temperature, and the amount of water lost through evaporation, including: The average temperature of the first surface is calculated based on the temperature distribution of a predetermined area of ​​the light-receiving surface during the first sampling period, and the average temperature of the second surface is calculated based on the temperature distribution of a predetermined area of ​​the light-receiving surface during the second sampling period. The first sampling period and the second sampling period are located before and after the change in water supply flow rate, respectively, and have the same duration. The first temperature difference is determined based on the average temperature of the first surface and the water supply side temperature during the first sampling period, and the second temperature difference is determined based on the average temperature of the second surface and the water supply side temperature during the second sampling period. The change in water loss is determined based on the evaporation water loss during the first and second sampling periods. The temperature compensation value is determined by using the correspondence between the preset change in water loss and the temperature compensation value. The second temperature difference is then corrected using the temperature compensation value to obtain the second corrected temperature difference. Based on the first temperature difference and the second corrected temperature difference, and using the pre-calibrated correspondence between temperature difference and heat transfer based on water supply flow rate, the heat transfer on the first water supply side and the heat transfer on the second water supply side are determined, and the heat transfer on the second water supply side is defined as the heat loss on the water supply side.

[0012] In one feasible implementation, determining the light energy loss caused by salt crystal coverage based on the reflectance spectrum before and after the change in incident irradiance intensity includes: Select the target reflectance spectrum before and after the incident irradiance intensity changes while keeping the water supply flow rate constant; The target reflectance spectrum is divided into predetermined bands to obtain the reflectance of the bands before and after the change. Using the reflectivity of the corresponding band under the condition of no salt crystal coverage as the reference reflectivity, the first reflectivity increment and the second reflectivity increment of the band reflectivity before and after the change relative to the reference reflectivity are determined respectively. The irradiance weight of each predetermined band is determined according to the simulated irradiance intensity distribution of sunlight in the predetermined band. The first reflectance increment and the second reflectance increment are accumulated according to the corresponding irradiance weights to obtain the first reflection loss ratio and the second reflection loss ratio. The reflection loss ratio is determined based on the first reflection loss ratio and the second reflection loss ratio. The light energy loss caused by salt crystal coverage is then calculated using the reflection loss ratio, the corresponding incident irradiance, the light-receiving area, and the sampling time.

[0013] In one feasible implementation, the interfacial evaporation heat consumption is determined based on the amount of water lost through evaporation, the solution temperature, and the salt concentration at the evaporation interface, including: Select the evaporation water loss, solution temperature, and salt concentration at the evaporation interface corresponding to the collection period when the salt crystals are not covered from the detection data; Based on the solution temperature, the first latent heat of vaporization is determined from the preset relationship between temperature and latent heat of vaporization of water. The salt concentration at the evaporation interface is compared with the preset reference salt concentration to obtain the salt concentration deviation, and the corresponding salinity correction coefficient is determined according to the preset salt concentration range in which the salt concentration deviation is located. The first latent heat of vaporization is corrected using a salinity correction coefficient to obtain the second latent heat of vaporization. The heat consumption of interfacial evaporation is then calculated based on the product of the water loss due to evaporation and the second latent heat of vaporization.

[0014] In one feasible implementation, during the collection period when the salt crystals are not covered, the photothermal conversion efficiency is calculated based on the incident irradiance, light energy loss, heat transfer loss on the water supply side, and heat consumption from interfacial evaporation, including: Determine the light-receiving area and collection duration corresponding to the collection period when the salt crystals are not covered, and select the incident irradiance, light energy loss, water supply side heat transfer loss and interface evaporation heat consumption corresponding to the collection period from the detection data; The incident light energy during the collection period is calculated by multiplying the incident irradiance, the light-receiving area, and the collection time. The effective absorbed light energy is calculated based on the difference between the incident light energy and the light energy loss. The heat loss from interfacial evaporation and the heat loss from water supply are added together to obtain the photothermal conversion heat. The photothermal conversion efficiency is determined by calculating the ratio of the photothermal conversion heat to the effective absorbed light energy.

[0015] Secondly, this application provides a photothermal conversion efficiency testing system for photothermal conversion materials, comprising: The recording module is used to place the photothermal conversion material at the liquid surface of the evaporation unit so that the light-receiving surface is above the liquid surface, and to evaporate and record the incident irradiance under simulated sunlight and continuous water supply. The data acquisition module is used to continuously collect detection data, including reflectance spectrum, temperature distribution of the light-receiving surface, water supply side temperature, water supply volume, solution mass change, solution temperature and salt concentration at the evaporation interface. The amount of water lost through evaporation is determined based on the water supply volume and solution mass change. The determination module is used to determine the salt crystal uncovered state, salt crystal formed state, salt crystal covered state, and salt crystal dissolved state based on the continuously collected reflectance spectrum and the salt concentration at the evaporation interface. The acquisition module is also used to determine the target time based on the rate of change of salt concentration at the evaporation interface during the cycle from salt crystal formation state to salt crystal dissolution state. Starting from the target time, the water supply flow rate is changed while keeping the incident irradiance constant, and then the incident irradiance is changed while keeping the water supply flow rate constant. Data is collected before and after each change. The determination module is also used to determine the heat transfer loss on the water supply side based on the temperature distribution of the light-receiving surface, the water supply side temperature, and the amount of water loss due to evaporation before and after the change in water supply flow rate; to determine the light energy loss caused by salt crystal coverage based on the reflection spectrum before and after the change in incident irradiance intensity; and to determine the heat consumption of interfacial evaporation based on the amount of water loss due to evaporation, the solution temperature, and the salt concentration at the evaporation interface. The calculation module is used to calculate the photothermal conversion efficiency based on the incident irradiance, light energy loss, heat transfer loss on the water supply side, and heat consumption from interface evaporation during the collection period when the salt crystals are not covered.

[0016] Thirdly, this application provides an electronic device, comprising: Memory, used to store computer programs; A processor is used to execute a computer program to implement the steps of the photothermal conversion efficiency detection method for photothermal conversion materials as described in the first aspect above.

[0017] This application continuously collects reflectance spectra, temperature, water loss, and salt concentration at the evaporation interface under continuous interfacial evaporation conditions in high-salinity concentrated seawater or brackish water. Based on this, it determines the states of salt crystal coverage (uncovered, formed, covered, and dissolved), ensuring that the evaluation data for photothermal conversion efficiency corresponds to a clear material surface state and avoiding the mixing of detection data from different crystallization states. Furthermore, during the cycle from salt crystal formation to salt crystal dissolution, the water supply flow rate is changed sequentially while maintaining a constant incident irradiance, and then the incident irradiance is changed while maintaining a constant water supply flow rate. This makes the detection data caused by changes in water supply conditions and illumination conditions comparable. By combining reflectance spectra, the temperature distribution of the illuminated surface, the water supply side temperature, and the evaporation water loss, the light energy loss caused by salt crystal coverage, the heat transfer loss on the water supply side, and the heat consumption of interfacial evaporation can be obtained separately. Calculating the photothermal conversion efficiency based on the aforementioned data during the collection period in the uncovered salt crystal state can reduce the impact of salt enrichment and changes in operating state during high-salinity evaporation on efficiency evaluation. Therefore, this invention can improve the accuracy and comparability of photothermal conversion efficiency test results for photothermal conversion materials under high-salinity conditions.

[0018] Furthermore, by combining the rate of change of salt concentration at the evaporation interface, the change in reflectance spectrum, and the change in evaporative water loss before the target time, the changes in water supply flow rate and incident irradiance intensity are determined, ensuring that the adjustment range under high-salt evaporation conditions is adapted to the current operating state of the material. Furthermore, by determining the relative magnitude or simultaneous increase method of the two changes based on the comparison results of different detection data relative to a preset range, situations where the response is not obvious or the operating state changes excessively can be avoided when using a fixed adjustment range. This application is beneficial for improving the stability of the photothermal conversion efficiency detection process and the reliability of the detection results under high-salt conditions. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the 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.

[0020] Figure 1 A schematic flowchart illustrating a method for detecting the photothermal conversion efficiency of a photothermal conversion material provided in an embodiment of this application; Figure 2 This is a schematic diagram illustrating a salt crystal state transition process provided in an embodiment of this application; Figure 3 A flowchart illustrating a method for determining the proportion of change in water supply flow rate and the proportion of change in incident irradiation intensity, provided for an embodiment of this application; Figure 4 This is a schematic diagram of the structure of a photothermal conversion efficiency detection system for photothermal conversion materials provided in an embodiment of this application; Figure 5 This is a schematic diagram of the hardware structure of an electronic device provided in one embodiment of this application. Detailed Implementation

[0021] This application addresses scenarios involving continuous interfacial evaporation and evaporative crystallization in high-salinity concentrated seawater, brackish water, and reverse osmosis concentrated brine. In these scenarios, the photothermal conversion material is continuously exposed to simulated sunlight and water is supplied to the evaporation interface. Water evaporation gradually increases the interfacial salt concentration, and the material surface may undergo changes in its operational state, including salt crystal formation, deposition, and dissolution. Salt crystal deposition affects the optical and evaporation states of the material surface, and changes in water supply also alter the heat transfer state between the material and the water supply side. This means that the water loss measured at different times cannot consistently reflect the material's photothermal conversion capacity. Existing methods often use single or short-term water loss as the evaluation basis, making it difficult to distinguish between changes in material performance and changes in operational state under high-salinity dynamic crystallization conditions. This affects the accuracy of photothermal conversion efficiency evaluation and the comparability between materials.

[0022] To address the aforementioned issues, this application does not treat the high-salt evaporation process as a constant state, but rather uses the salt crystal state change process as the time basis for efficiency testing. By continuously obtaining reflectance spectra, temperature, water supply, water loss, and salt concentration at the evaporation interface, the salt crystal state on the material surface is first determined. Then, during the process from salt crystal formation to salt crystal dissolution, the target time is determined by the changes in reflectance spectra and salt concentration, and the water supply flow rate and incident irradiance are changed sequentially to allow for comparison of the test data caused by different condition changes. Subsequently, by combining optical, temperature, and water loss data, the changes in light energy caused by salt crystal coverage, heat transfer on the water supply side, and heat consumption of interface evaporation are determined separately. The photothermal conversion efficiency is obtained in the state without salt crystal coverage, making the test results more reflective of the actual photothermal conversion performance of the photothermal conversion material under high-salt continuous evaporation conditions.

[0023] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of the present application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] To address the problems of the prior art, embodiments of this application provide a method, apparatus, device, computer storage medium, and computer program product for detecting the photothermal conversion efficiency of photothermal conversion materials. The method for detecting the photothermal conversion efficiency of photothermal conversion materials provided in this application embodiment will be described first below.

[0025] Figure 1 A schematic flowchart of a method for detecting the photothermal conversion efficiency of a photothermal conversion material according to an embodiment of this application is shown. Figure 1 As shown, the method includes steps S110 to S160.

[0026] S110. Place the photothermal conversion material at the liquid surface of the evaporation unit so that the light-receiving surface is above the liquid surface, and evaporate it under simulated sunlight and continuous water supply, and record the incident irradiance.

[0027] The photothermal conversion material used for testing can be any material with a light-receiving surface and a water-supply side, capable of forming an evaporation interface near the liquid surface. There are no limitations on the material, shape, thickness, pore structure, or preparation method of the photothermal conversion material. The evaporation unit may include a solution container, a floating or supporting structure for positioning the photothermal conversion material, a water supply path, a liquid transfer pump, and an overflow structure for maintaining the liquid surface. Before testing begins, the projected area of ​​the photothermal conversion material in the simulated sunlight irradiation direction is measured and recorded as the light-receiving area. The incident irradiance intensity is recorded in watts per square meter, and each set of incident irradiance intensity data includes the acquisition time and the corresponding irradiance intensity.

[0028] In practice, the solution to be treated is added to the evaporation unit. The solution can be high-salinity concentrated seawater or brackish water; in the embodiment of high-salinity concentrated seawater, the total salt concentration of the solution is 160 g / L, and the initial temperature is 25 degrees Celsius. The photothermal conversion material is installed on the floating structure or support structure, so that the light-receiving surface is above the liquid surface, and the water supply side is connected to the water supply passage. The liquid level is kept stable by an overflow structure, and the distance between the light-receiving surface and the liquid surface can be 2 mm. The light-receiving area can be 9 square centimeters.

[0029] The liquid transfer pump is started to continuously supply the solution to be treated to the water supply side at an initial water flow rate. The initial water flow rate is determined based on the light-receiving area and water supply capacity of the photothermal conversion material, aiming to form a continuous liquid film near the light-receiving surface without overflow. In the embodiment with a light-receiving area of ​​9 square centimeters, the initial water flow rate is 0.05 ml per minute. After continuous water supply for 10 minutes, the water supply path inside or at the bottom of the photothermal conversion material remains connected to the solution to be treated, a stable evaporation interface is formed near the light-receiving surface, and the light-receiving surface remains above the liquid surface.

[0030] A simulated solar light source was positioned above the illuminated surface, ensuring its illumination covered the entire area. The spectral distribution of the simulated solar light source matched the AM1.5G solar reference spectrum, and the initial incident irradiance was set to 1000 watts per square meter. Irradiance was collected at the center and four edge locations of the illuminated surface. The average irradiance at these five locations was recorded as the incident irradiance at the time of collection, with the deviation of the irradiance at each location from the average value controlled within 5%.

[0031] During the simulation of sunlight exposure and continuous water supply, the incident irradiance was recorded every 10 seconds, and the acquisition time was recorded using the same timing reference as the subsequent detection data.

[0032] S120. Continuously collect detection data, including reflectance spectrum, temperature distribution of the light-receiving surface, water supply side temperature, water supply volume, solution mass change, solution temperature and salt concentration at the evaporation interface, and determine the amount of water lost through evaporation based on the water supply volume and solution mass change.

[0033] During continuous evaporation, the timing reference used to record the incident irradiance intensity in S110 was used as the unified timing reference. The reflectance spectrum, the temperature distribution of the illuminated surface, the water supply side temperature, the water supply volume, the solution mass change, the solution temperature, and the salt concentration at the evaporation interface were all recorded at the unified timing reference. A set of detection data was generated every 10 seconds, with each data point corresponding to the same acquisition time.

[0034] The reflectance spectrum was obtained using a spectral acquisition device fixed above the illuminated surface. The spectral acquisition device underwent reflectance calibration using a standard reflective surface before detection began and collected reflectance data in the 400 nm to 1100 nm wavelength range during continuous evaporation. The temperature distribution of the illuminated surface was obtained using a thermal infrared imaging device. The thermal infrared imaging device's imaging range covered the entire illuminated area and underwent temperature calibration using a contact temperature sensor before detection began. The temperature distribution data included multiple temperature sampling locations and corresponding temperature values, with the temperature unit being degrees Celsius. A predetermined area of ​​the illuminated surface was determined during the initial temperature distribution data acquisition and remained unchanged throughout the entire detection process.

[0035] The water supply temperature is collected by a temperature sensor located near the outlet of the water supply path, adjacent to the water supply side of the photothermal conversion material. The water supply volume is obtained through a flow meter on the liquid transfer pump, which records the volume of solution input to the evaporation unit during each sampling period, in milliliters. Solution mass change is obtained using an electronic balance supporting the evaporation unit. No solution is discharged from the evaporation unit during the sampling period. The water supply path is connected to the evaporation unit via a flexible connection to minimize the impact of the water supply path on the electronic balance reading. The solution mass change is the solution mass at the end of the sampling period minus the solution mass at the beginning of the sampling period, in grams. The solution temperature is collected by a temperature sensor located at a fixed depth within the evaporation unit.

[0036] The salt concentration at the evaporation interface was obtained by collecting the interfacial conductivity using a miniature conductivity probe positioned near the evaporation interface. The probe's probe tip was fixed to the end of the water supply path of the photothermal conversion material, and the distance between the probe tip and the light-receiving surface remained constant. Before detection, multiple calibration solutions with the same salt composition but different salt concentrations as the solution to be treated were used to establish the correlation between conductivity, solution temperature, and salt concentration. After collecting the interfacial conductivity and solution temperature, the evaporation interface salt concentration was obtained based on the correlation, expressed in grams per liter.

[0037] The process of determining the evaporation loss includes converting the water supply volume in each collection period into water mass according to the density of the current water supply solution. The density of the water supply solution is determined based on the salt concentration and temperature of the solution. Then, the change in solution mass during the same collection period is subtracted from the water supply mass to obtain the evaporation loss.

[0038] S130. Based on the continuously collected reflectance spectra and the salt concentration at the evaporation interface, determine the salt crystal uncovered state, salt crystal formed state, salt crystal covered state, and salt crystal dissolved state.

[0039] like Figure 2 As shown, during the continuous evaporation process, the light-receiving surface of the photothermal conversion material sequentially experiences a salt crystal-free state, a salt crystal-forming state, a salt crystal-covered state, and a salt crystal-dissolved state. With the evaporation of water and the enrichment of salt, the light-receiving surface transitions from the salt crystal-free state to the salt crystal-forming state, and after further salt crystal deposition, it enters the salt crystal-covered state. Under continuous water supply, the salt crystal cover layer gradually dissolves and enters the salt crystal-dissolved state, subsequently returning to the salt crystal-free state, forming a repeating state cycle.

[0040] In practice, based on the continuously collected reflection spectrum and salt concentration data at the evaporation interface, it is determined in sequence whether each collection period meets the criteria for salt crystal uncovered state, salt crystal formed state, salt crystal covered state, and salt crystal dissolved state, and the corresponding state is marked for each collection period.

[0041] In one feasible implementation, step S130, based on continuously acquired reflectance spectra and salt concentration at the evaporation interface, determines the salt crystal uncovered state, salt crystal formed state, salt crystal covered state, and salt crystal dissolved state, including: If, within a continuous acquisition period, the change in reflection intensity of the reflection spectrum within a predetermined band does not exceed the first preset fluctuation threshold, and the change in salt concentration at the evaporation interface does not exceed the second preset fluctuation threshold, then it is determined to be a state where salt crystals are not covered. The predetermined wavelength band is selected from the reflectance spectrum acquisition range and remains constant throughout a cycle from salt crystal formation to salt crystal dissolution. In one embodiment, the predetermined wavelength band is 550 nm to 900 nm. The average reflectance of the predetermined band within a consecutive acquisition period is the average reflectance. The reference average reflectance during the period before salt crystals appear is the reference average reflectance. The change in reflection intensity within the predetermined band is the change in reflection intensity. . No. The evaporation interface salt concentration within a consecutive collection cycle is the interface salt concentration. The reference salt concentration is the reference salt concentration. The change in salt concentration at the evaporation interface is the change in salt concentration. .

[0042] , Among them, average reflectivity and reference average reflectance The unit is percentage, interfacial salt concentration. and reference salt concentration The unit is grams per liter, and the change in reflectance is... The unit is percentage, representing the change in salt concentration. The unit is grams per liter.

[0043] In practice, before salt crystals appear, reflectance spectra and salt concentration at the evaporation interface are collected for six consecutive acquisition cycles, and the reference average reflectance is calculated accordingly. and reference salt concentration The first preset fluctuation threshold is the maximum change in reflection intensity during the period when salt crystals are not present, plus twice the reflectivity measurement resolution. The second preset fluctuation threshold is the maximum change in salt concentration during the period when salt crystals are not present, plus twice the salt concentration measurement resolution. For the current continuous acquisition cycle, the change in reflection intensity and the change in salt concentration are compared with their respective preset fluctuation thresholds. When both data do not exceed their respective preset fluctuation thresholds, the current continuous acquisition cycle is recorded as a state where salt crystals are not covered.

[0044] If the change in salt concentration at the evaporation interface continues to increase, and the change in reflection intensity increases in two or more consecutive acquisition cycles, then it is determined to be a salt crystal formation state. The salt crystal formation state corresponds to a stage where the salt concentration at the evaporation interface gradually increases and the change in reflection intensity of the light-receiving surface continuously increases. A continuous increase in the change in salt concentration at the evaporation interface indicates that the change in salt concentration in the current continuous sampling period is greater than that in the previous continuous sampling period, and a continuous increase in the change in reflection intensity indicates that the change in reflection intensity in the current continuous sampling period is greater than that in the previous continuous sampling period.

[0045] In practice, after each continuous acquisition cycle, the changes in salt concentration and reflection intensity are compared between the current continuous acquisition cycle and the previous continuous acquisition cycle. When the change in salt concentration continues to increase and the change in reflection intensity increases sequentially in two or more consecutive acquisition cycles, the salt crystal formation state is determined, and the acquisition time when both conditions for increase are first met simultaneously is determined as the start time of the salt crystal formation state.

[0046] If the change in reflection intensity remains within the third preset fluctuation range within a preset time period, it is determined to be a salt crystal coverage state; The salt crystal coverage state corresponds to the stage after salt crystal formation, where the change in reflection intensity within a predetermined band enters a relatively stable range. The third preset fluctuation range is the allowable range of change in reflection intensity within the salt crystal coverage stage, and the preset duration can be the duration corresponding to six consecutive acquisition cycles.

[0047] In practice, a salt crystal formation experiment is conducted beforehand. A continuous and stable change in reflection intensity is selected within the salt crystal coverage phase. Based on the minimum and maximum values ​​of the stable data and the reflectivity measurement resolution, the lower and upper limits of the third preset fluctuation range are determined. After the salt crystal formation state is determined, the change in reflection intensity is continuously read. When the change in reflection intensity remains within the third preset fluctuation range for a preset duration, the salt crystal coverage state is determined, and the first continuous acquisition cycle that satisfies the third preset fluctuation range is defined as the start time of the salt crystal coverage state.

[0048] If the change in salt concentration at the evaporation interface decreases, and the difference between the change in reflection intensity and the change in reflection intensity under the uncovered salt crystal state decreases, then it is determined to be a salt crystal dissolved state.

[0049] The salt crystal dissolution state corresponds to the stage where the change in salt concentration at the evaporation interface decreases and the change in reflection intensity within a predetermined wavelength band falls back to the state where the salt crystal is not covered. The change in reflection intensity in the state where the salt crystal is not covered can be taken as the average of the change in reflection intensity in each sampling period of the salt crystal uncovered state before the start of the salt crystal formation state in the same salt crystal formation to salt crystal dissolution cycle.

[0050] Each consecutive acquisition cycle corresponds to only one salt crystal state marker, and the current state is determined according to the state of the previous consecutive acquisition cycle. If the previous state was an uncovered salt crystal state, it transitions to a salt crystal forming state after the salt crystal forming state condition is met; if the previous state was a salt crystal forming state, it transitions to a covered salt crystal state after the salt crystal covering state condition is met; if the previous state was a covered salt crystal state, it transitions to a dissolved salt crystal state after the salt crystal dissolution state condition is met; if the previous state was a dissolved salt crystal state, it transitions to an uncovered salt crystal state after the uncovered salt crystal state condition is met. Except for the above state transitions, the current acquisition cycle maintains the previous state.

[0051] The continuously increasing changes in salt concentration at the evaporation interface, the continuously increasing rate of change in salt concentration at the evaporation interface, and the continuously increasing changes in reflection intensity all indicate that the current acquisition cycle and the immediately preceding acquisition cycle share the same increasing trend. The target time should be determined using data from at least two consecutive acquisition cycles.

[0052] In practice, during the salt crystal coverage period, the changes in salt concentration and reflectance intensity are continuously compared between adjacent consecutive acquisition cycles. If the current salt concentration change is less than the change in salt concentration in the previous consecutive acquisition cycle, and the difference between the current reflectance intensity change and the reflectance intensity change in the salt crystal-free state is less than the corresponding difference in the previous consecutive acquisition cycle, the salt crystal dissolution state is determined. When the reflectance intensity change returns to within a first preset fluctuation threshold, and the salt concentration change returns to within a second preset fluctuation threshold, the salt crystal-free state is determined.

[0053] S140. During the cycle from salt crystal formation state to salt crystal dissolution state, the target time is determined based on the rate of change of salt concentration at the evaporation interface and the reflection spectrum. Starting from the target time, the incident irradiation intensity is kept constant while the water supply flow rate is changed. Then, the water supply flow rate is kept constant while the incident irradiation intensity is changed. Data is collected before and after each change.

[0054] The target time is the moment when data collection begins during the cycle from salt crystal formation to salt crystal dissolution, coinciding with changes in water supply flow rate and incident radiation intensity. The rate of change of salt concentration at the evaporation interface during each consecutive sampling cycle is the rate of change of salt concentration. It is used to characterize the rate of change of salt concentration at the evaporation interface with the time of collection.

[0055] like Figure 2 As shown, the target time is during the salt crystal formation process, and the process from the start of the salt crystal formation state to the end of the salt crystal dissolution state is considered as one detection cycle. After the target time, the water supply flow rate and the incident irradiance intensity are changed sequentially, and detection data are collected before and after the corresponding changes, so that the changes in water supply conditions and irradiance conditions within the same cycle can be used separately for subsequent loss determination.

[0056] In the formula, the interfacial salt concentration For the first The evaporation interface salt concentration for each consecutive sampling period, interface salt concentration The concentration of salt at the evaporation interface in the previous consecutive sampling period, at the sampling time. For the first The acquisition time of each consecutive acquisition cycle, acquisition time This refers to the data collection time in the previous consecutive data collection cycle. Rate of change in salt concentration. The unit is grams per liter per second.

[0057] In practice, the rate of change of salt concentration is continuously calculated within the salt crystal formation state, and the target time is determined by combining the trend of the reflection spectrum. After the target time is determined, the water supply flow rate is changed and detection data is collected while keeping the incident irradiance constant. Then, the incident irradiance is changed and detection data is collected while keeping the water supply flow rate constant, thereby separating the effects of changes in water supply flow rate and changes in incident irradiance on the detection data.

[0058] In one feasible implementation, determining the target time in step S140 based on the reflectance spectrum and the rate of change of salt concentration at the evaporation interface includes: During the cycle from salt crystal formation state to salt crystal dissolution state, the change in reflection intensity of the reflection spectrum within a predetermined band is determined; Variation in reflection intensity within the predetermined band The predetermined waveband, reference average reflectance, and calculation method determined in S130 are used. The cycle from salt crystal formation state to salt crystal dissolution state begins at the acquisition time when the change in reflection intensity continuously increases and ends at the acquisition time when the change in reflection intensity returns to within the first preset fluctuation threshold.

[0059] In practice, after the salt crystal formation begins, the average reflectance within a predetermined wavelength band is extracted sequentially according to the continuous acquisition cycle, and compared with the reference average reflectance to obtain the change in reflection intensity for each continuous acquisition cycle. The changes in reflection intensity are then sorted according to the acquisition time to form a sequence of reflection intensity changes; as the changes in reflection intensity in adjacent continuous acquisition cycles increase sequentially, the corresponding increasing trend is recorded.

[0060] If the rate of change of salt concentration at the evaporation interface continues to increase, and the change in reflection intensity increases in two or more consecutive acquisition cycles, then the acquisition time at which the aforementioned changes are simultaneously met for the first time will be determined as the target time.

[0061] A continuously increasing rate of change in salt concentration at the evaporation interface indicates the rate of change in salt concentration during the current continuous sampling period. The rate of change of salt concentration is greater than that of the previous consecutive sampling period. And the current rate of change of salt concentration The value is positive. The first time that the aforementioned changes are simultaneously satisfied indicates that the rate of increase in salt concentration and the rate of increase in reflectance intensity are satisfied for the first time at the same sampling time.

[0062] In practice, after each continuous acquisition cycle, the current rate of change of salt concentration is compared with the rate of change of salt concentration in the previous continuous acquisition cycle, and the current change in reflection intensity is compared with the change in reflection intensity in the previous continuous acquisition cycle. When the rate of change of salt concentration increases sequentially in two or more consecutive acquisition cycles, and the change in reflection intensity increases sequentially in the same consecutive acquisition cycle, the acquisition time that first satisfies both conditions is determined as the target time.

[0063] In one feasible implementation, the solution within the evaporation unit can be high-salinity concentrated seawater or brackish water. The method may further include: before a target time, determining the proportion of change in water supply flow rate and the proportion of change in incident irradiance intensity from the target time, based on the rate of change in salt concentration at the evaporation interface, the amount of change in reflection intensity within a predetermined wavelength band, and the amount of change in water loss due to evaporation; the predetermined wavelength band is selected from the range of the reflection spectrum and remains constant throughout a cycle from salt crystal formation to salt crystal dissolution; from the target time, the water supply flow rate is changed according to the proportion of change in water supply flow rate, and the incident irradiance intensity is changed according to the proportion of change in incident irradiance intensity.

[0064] The percentage change in water supply flow rate represents the difference between the setpoint for water supply flow rate adjustment and the average water supply flow rate during the stable sampling period before the change, expressed as a percentage relative to the average water supply flow rate. The percentage change in incident radiation intensity is determined in the same manner, with the baseline value being the average incident radiation intensity during the stable sampling period before the change. Both percentage changes are expressed as percentages, with positive values ​​indicating an increase, negative values ​​indicating a decrease, and zero values ​​indicating no change.

[0065] In practice, before the target time, a continuous data acquisition period of the same duration is selected from the continuously acquired data. The rate of change of salt concentration at the evaporation interface, the change of reflection intensity within the predetermined wavelength band, and the change of evaporative water loss are calculated and compared with the corresponding preset ranges. Based on the comparison results, the water supply flow rate change ratio and the incident irradiance change ratio are selected from a preset candidate set of ratios. The candidate set of ratios can include -20%, -15%, -10%, -5%, 0%, 5%, 10%, 15%, and 20%, and is determined with the boundary conditions of continuous liquid film formation on the illuminated surface, no interruption or overflow of water supply, and stable simulated solar irradiation. In actual execution, the liquid delivery pump is adjusted first, and then the simulated solar irradiance is adjusted.

[0066] In one feasible implementation, the proportion of change in water supply flow rate and the proportion of change in incident irradiance intensity from the target time are determined based on the rate of change of salt concentration at the evaporation interface, the change in reflection intensity within a predetermined wavelength band, and the change in evaporative water loss, including: S141. Compare the rate of change of salt concentration at the evaporation interface, the change of reflection intensity in the predetermined band, and the change of evaporation water loss with the corresponding preset ranges. The rate of change of salt concentration at the evaporation interface is calculated using the rate of change of salt concentration in step S140. The change in reflection intensity within the predetermined band is calculated using the change in reflection intensity in step S130. The change in evaporative water loss is the difference between the evaporative water loss in the current continuous acquisition period and the evaporative water loss in the previous continuous acquisition period, with the two continuous acquisition periods having the same duration.

[0067] In practice, preliminary testing is conducted under the same photothermal conversion materials, the same high-salinity concentrated seawater or brackish water, the same initial water supply flow rate, and the same initial incident irradiance. Within the uncovered salt crystal state, the rate of change in salt concentration, the change in reflectance intensity, and the change in evaporation loss are continuously collected for at least six consecutive time periods, and the average value, sample standard deviation, and measurement resolution are calculated for each. The upper limit of each preset range is the larger of the average value plus three times the sample standard deviation and twice the measurement resolution, and the lower limit of each preset range is the larger of the average value minus three times the sample standard deviation and twice the measurement resolution. When the lower limit of the reflectance intensity change is less than zero, the lower limit is set to zero. If the current data is higher than the upper limit or lower than the lower limit, it is determined to be outside the corresponding preset range.

[0068] S142. If the change in reflection intensity within the predetermined band exceeds the corresponding preset range, and the change in evaporation water loss does not exceed the corresponding preset range. S143, Make the absolute value of the change ratio of incident radiation intensity greater than the absolute value of the change ratio of water supply flow rate; If the absolute value of the change in incident radiation intensity is greater than the absolute value of the change in water supply flow rate, it indicates that the relative adjustment range of incident radiation intensity is greater than the relative adjustment range of water supply flow rate. Using absolute values ​​for comparison can avoid inconsistencies in the comparison results of adjustment ranges when the two changes have different signs.

[0069] In practice, two change ratios with different absolute values ​​are selected from the candidate ratio set. The change ratio for water supply flow can be 5%, and the change ratio for incident irradiance can be 15%. First, with the incident irradiance remaining constant, the liquid delivery pump is adjusted to the set value after the change in water supply flow. After the water supply flow stabilizes, detection data is collected for the same duration as before the change. Then, keeping the changed water supply flow constant, the simulated solar light source is adjusted to the set value after the change in incident irradiance. After the incident irradiance stabilizes, detection data is collected for the same duration as before the change.

[0070] S144. If the change in evaporation loss exceeds the corresponding preset range, and the change in reflection intensity within the predetermined band does not exceed the corresponding preset range. S145. Make the absolute value of the change in water supply flow rate greater than the absolute value of the change in incident radiation intensity. The absolute value of the change in water supply flow rate is greater than the absolute value of the change in incident irradiance, indicating that the relative adjustment range of water supply flow rate is greater than the relative adjustment range of incident irradiance. The range of values ​​for the candidate set of proportions is jointly defined by the allowable flow rate range of the liquid transfer pump, the water supply capacity of the photothermal conversion material, and the allowable output range of the simulated solar light source.

[0071] In practice, the change in water supply flow rate can be taken as 15%, and the change in incident radiation intensity can be taken as 5%. The liquid transfer pump first increases the water supply flow rate by 15%, simulating that the solar light source remains constant before and after the change in water supply flow rate. After collecting the detection data after the change in water supply flow rate, the water supply flow rate is kept stable, and then the incident radiation intensity is increased by 5% and detection data is collected again.

[0072] S146. The rate of change of salt concentration at the evaporation interface exceeds the corresponding preset range, while the change in reflection intensity and the change in evaporation water loss within the predetermined band do not exceed the corresponding preset range. S147. Simultaneously increase the water supply flow rate and the incident radiation intensity so that the change ratio of the water supply flow rate and the change ratio of the incident radiation intensity are both positive.

[0073] Simultaneously increasing water flow rate and incident radiation intensity indicates that two positive change ratios are determined at the same target time, but does not mean that the two physical quantities are adjusted at the same moment. When both change ratios are greater than zero, both water flow rate and incident radiation intensity increase relative to their corresponding baseline values ​​before the change.

[0074] In practice, the percentage change in water supply flow rate and the percentage change in incident irradiance intensity can both be set to 10%, or different positive proportions can be selected from the candidate set of proportions. First, the water supply flow rate is adjusted and the detection data is collected under the initial incident irradiance intensity, and then the incident irradiance intensity is adjusted and the detection data is collected under the changed water supply flow rate. The actual adjustment sequence is consistent with step S140.

[0075] After determining the target time, it is determined whether the changes in reflectance intensity, evaporation loss, and the rate of change in salt concentration at the evaporation interface exceed the corresponding preset ranges. If only the change in reflectance intensity exceeds the preset range, the positive and negative directions of the change ratios of incident irradiance intensity and water supply flow rate are determined according to the upper or lower limit of the change in reflectance intensity relative to the preset range, ensuring that the absolute value of the change ratio of incident irradiance intensity is large. If only the change in evaporation loss exceeds the preset range, the positive and negative directions of the change ratios of water supply flow rate and incident irradiance intensity are determined according to the upper or lower limit of the change in evaporation loss relative to the preset range, ensuring that the absolute value of the change ratio of water supply flow rate is large.

[0076] If only the rate of change of salt concentration at the evaporation interface exceeds the preset range, and the changes in reflectance intensity and evaporation loss do not exceed their respective preset ranges, both the percentage change in water supply flow rate and the percentage change in incident irradiance intensity will be positive. If both the changes in reflectance intensity and evaporation loss exceed the preset range simultaneously, or if the rate of change of salt concentration at the evaporation interface exceeds the preset range and any other indicator exceeds the preset range, the current detection cycle will not perform parameter changes, maintaining the water supply flow rate and incident irradiance intensity as before the change, and data for the continuous acquisition cycle will be re-acquired. If none of the three indicators exceed their respective preset ranges, both percentage changes will be zero.

[0077] After each parameter change, six consecutive acquisition cycles with ten-second intervals are collected. When both the liquid transfer pump output flow rate and the incident irradiance are within their respective preset stable ranges, the data from these six acquisition cycles are used for subsequent calculations; if any parameter is unstable, the data from the current acquisition period is discarded and the current detection cycle is restarted.

[0078] During the detection of high-salinity concentrated seawater, when continuous data collection during the salt crystal formation period simultaneously shows a continuous increase in both the rate of salt concentration change and the amount of reflection intensity change, the collection time that first satisfies both conditions is determined as the target time. Before the target time, the proportion of water supply flow rate change and the proportion of incident radiation intensity change are determined using three change data points within the continuous collection period, and the corresponding values ​​in the candidate set of proportions are selected according to the comparison results of steps S141 to S144.

[0079] Once the target time is reached, first maintain the incident radiation intensity constant and complete the data collection before and after the change in water supply flow rate; then maintain the changed water supply flow rate constant and complete the data collection before and after the change in incident radiation intensity. The data collection period before and after the change in water supply flow rate can both be 60 seconds, and the data collection period before and after the change in incident radiation intensity can both be 60 seconds. The data can be recorded at 10-second intervals.

[0080] S150. Determine the heat transfer loss on the water supply side based on the temperature distribution of the light-receiving surface before and after the change in water supply flow rate, the temperature on the water supply side, and the amount of water lost through evaporation. Determine the light energy loss caused by salt crystal coverage based on the reflection spectrum before and after the change in incident irradiance intensity. Determine the heat consumption of interfacial evaporation based on the amount of water lost through evaporation, the solution temperature, and the salt concentration at the evaporation interface.

[0081] Heat transfer loss on the water supply side is the energy of heat absorbed by the photothermal conversion material transferred to the solution to be treated via the water supply side, accumulated over a single sampling period and measured in joules. Light energy loss due to salt crystal coverage and heat consumption from interfacial evaporation are both measured in joules.

[0082] In practice, the first and second sampling periods are extracted from the detection data before and after the change in water supply flow rate, and then the heat transfer loss on the water supply side is calculated. The reflected spectrum before and after the change in incident irradiance intensity constitutes light energy loss, while the evaporation water loss in the uncovered salt crystal state, solution temperature, and salt concentration at the evaporation interface constitute interfacial evaporation heat consumption. These three types of energy are uniformly converted into joules.

[0083] The heat transfer loss on the water supply side in this application refers to the heat loss relative to the interface evaporation channel. This portion of heat still belongs to the heat generated after the photothermal conversion material absorbs light energy, and together with the heat consumed by interface evaporation, it constitutes the conversion heat when calculating the photothermal conversion efficiency. The light energy loss caused by salt crystal coverage is only used to characterize the incident light energy that was not absorbed by the material during the corresponding salt crystal state acquisition period, and does not transfer to the salt crystal uncovered state across acquisition periods.

[0084] The reflectance spectral acquisition range used for light energy loss calculation is divided into non-overlapping third... Each sub-band. The reflectance of each sub-band in the absence of salt crystal coverage is denoted as The reflectance before and after the change in incident irradiance intensity is denoted as follows: and Reflectivity is expressed as a decimal; when collected as a percentage, it is first divided by 100% before being included in the calculation.

[0085] Simulated sunlight in the first The irradiance weight within each sub-band is denoted as , determined by the spectral irradiance of the calibrated light source Sure, In this calculation, the sum of the irradiance weights for each sub-band is one. The corresponding spectrum can only be used to calculate light energy loss if the deviation of the spectral shape from the calibrated spectrum before and after the change in light source output does not exceed a preset stability threshold.

[0086] The ratios of reflection loss before and after the change in incident irradiance intensity are denoted as follows: and . ,in, It is either one or two. The reflection loss ratio for the current acquisition period is denoted as... And determine it according to the following formula. The two sampling periods before and after the change in incident irradiance have the same duration and correspond to the same salt crystal state markers. Inconsistent salt crystal states between the two sampling periods, missing any sub-band, or... and When the difference exceeds the preset stability threshold, the current light energy loss is not calculated, the detection conditions before the change are restored, and the data is collected again.

[0087] The average value before and after the change in incident radiation intensity is denoted as The area receiving light is denoted as The sampling duration is recorded as The light energy loss in the salt crystal covered or salt crystal formed state is... for During the target acquisition period when the salt crystals are not covering the target, if the reflectivity of each sub-band is relative to... If all changes are within the first preset fluctuation threshold, then take... and Used to calculate photothermal conversion efficiency , The heat transfer loss on the water supply side and the heat consumption of interface evaporation were both collected from the same target data collection period.

[0088] In one feasible implementation, step S150, which determines the heat transfer loss on the water supply side based on the temperature distribution of the light-receiving surface before and after the change in water supply flow rate, the water supply side temperature, and the amount of water lost through evaporation, includes: The average temperature of the first surface is calculated based on the temperature distribution of a predetermined area of ​​the light-receiving surface during the first sampling period, and the average temperature of the second surface is calculated based on the temperature distribution of a predetermined area of ​​the light-receiving surface during the second sampling period. The first sampling period and the second sampling period are located before and after the change in water supply flow rate, respectively, and have the same duration. The predetermined area can be a continuous region in the center of the light-receiving surface, avoiding material edges, areas obstructed by supporting structures, and areas that cannot be stably identified by thermal infrared imaging. The average temperature of the first surface is the first surface temperature. The average temperature of the second surface is the temperature of the second surface. First surface temperature Second surface temperature All values ​​are the average temperature of all valid temperature sampling locations in the predetermined area within the corresponding sampling period, in degrees Celsius.

[0089] In practice, each sampling period consists of six consecutive acquisition cycles spaced ten seconds apart. For each temperature distribution image, the effective temperature sampling locations within a predetermined area are extracted, and the average temperature of that area is calculated. Then, the arithmetic mean of the six average temperatures is taken to obtain the first surface temperature. Second surface temperature Sampling locations with missing temperatures or exceeding the range of the thermal infrared imaging device are not included in the calculation.

[0090] The first temperature difference is determined based on the average temperature of the first surface and the water supply side temperature during the first sampling period, and the second temperature difference is determined based on the average temperature of the second surface and the water supply side temperature during the second sampling period. The average temperature of the water supply side during the first sampling period is the first water supply temperature. The average temperature of the water supply side during the second sampling period is the second water supply temperature. The first temperature difference is the first temperature difference. The second temperature difference is the second temperature difference. First temperature difference Second temperature difference It is used to express the average temperature difference between the light-receiving surface and the water supply side, and the unit is Kelvin, which is numerically the same as the temperature difference in degrees Celsius.

[0091] , Among them, the first surface temperature Second surface temperature The unit is Celsius, the first water supply temperature Second water supply temperature The unit is Celsius, the first temperature difference Second temperature difference The unit is Kelvin.

[0092] In practice, the first water supply temperature is obtained by averaging the values ​​collected by the temperature sensor near the water supply outlet during the corresponding sampling period. Second water supply temperature The distance between the temperature sensor and the water supply side of the photothermal conversion material remains constant during the detection process. First temperature difference. Or the second temperature difference When the value is greater than zero, heat is transferred from the surface receiving the light to the water supply side.

[0093] The change in water loss is determined based on the evaporation water loss during the first and second sampling periods. The temperature compensation value is determined by using the correspondence between the preset change in water loss and the temperature compensation value. The second temperature difference is then corrected using the temperature compensation value to obtain the second corrected temperature difference. The evaporation loss during the first sampling period is the first water loss. The evaporation loss during the second sampling period is the second water loss. The sampling period duration is the sampling duration. The change in water loss is expressed as the change in the rate of water loss. The value is expressed in kilograms per second. The temperature compensation value is the compensation value. This is used to represent the effect of changes in evaporation loss on the second temperature difference. The resulting temperature shift, in Kelvin. The second corrected temperature difference is the second corrected temperature difference. The unit is Kelvin.

[0094] , Among them, the first water loss Second water loss The unit is kilogram, and the sampling time is... The unit is seconds, and the change in water loss rate is... The unit is kilograms per second, and the compensation value is... Second Corrected Temperature Difference The unit is Kelvin.

[0095] In practice, the same photothermal conversion material, solution to be treated, light-receiving area, and water supply structure as in the detection stage are used for preliminary calibration. While maintaining a constant water supply flow rate and incident irradiance in the absence of salt crystal coverage, the partial pressure of water vapor in the gas surrounding the evaporation unit is varied to obtain multiple evaporation water loss levels. Under each stable condition, the evaporation water loss and temperature difference are recorded to form the change in water loss rate. Compensation value The corresponding table. Current change in water loss rate. When located between two adjacent calibration points, linear interpolation is used to determine the compensation value. Current change in water loss rate If the value exceeds the calibration range, supplement the calibration data. When evaporation water loss increases and causes cooling of the light-receiving surface, adjust the compensation value. A positive value is used to compensate for the second temperature difference. The cooling portion; when evaporative water loss decreases, the compensation value... It is a negative value.

[0096] When establishing the correlation between the change in water loss rate and the temperature compensation value, the same photothermal conversion material, light-receiving area, salt composition of the solution to be treated, initial salt concentration, water supply structure, and simulated solar light source were used as in the formal testing. Under conditions where salt crystals were not covered, the surface temperature difference obtained under standard water vapor partial pressure was used as the reference temperature difference; after changing the water vapor partial pressure, the difference between the reference temperature difference and the measured second temperature difference was used as the temperature compensation value.

[0097] Each row of the actual calibration table records the change in water loss rate, temperature compensation value, temperature of the solution to be treated, water supply flow rate, and incident irradiance. At least three independent data acquisitions are performed at each calibration point, and the arithmetic mean of the three acquisitions is written into the calibration table. During formal testing, only linear interpolation is performed between the minimum and maximum water loss rate changes in the calibration table; if the value exceeds this range, boundary values ​​are not used for substitution.

[0098] Based on the first temperature difference and the second corrected temperature difference, and using the pre-calibrated correspondence between temperature difference and heat transfer based on water supply flow rate, the heat transfer on the first water supply side and the heat transfer on the second water supply side are determined, and the heat transfer on the second water supply side is defined as the heat loss on the water supply side.

[0099] The pre-calibrated relationship between temperature difference and heat transfer was established according to the water supply flow range, salt crystal state, salt concentration range at the evaporation interface, and incident irradiation intensity range. First temperature difference Corresponding to the first water supply side heat transfer power, the second corrected temperature difference The corresponding heat transfer power on the second water supply side. The heat transfer power on the second water supply side is the heat transfer power. The unit is watts.

[0100] In practice, during the preliminary calibration phase, temperature sensors are installed at the inlet of the water supply path and the return flow point on the water supply side to record the return fluid mass, inlet temperature, return temperature, and sampling duration. The return fluid mass is the return mass. The specific heat capacity of the reflux liquid is the specific heat capacity. The reflux temperature rise is the reflux temperature rise. .

[0101] Among them, reflux quality The unit is kilogram, specific heat capacity The unit is joules per kilogram per Kelvin, reflux temperature rise. The unit is Kelvin, and the sampling duration is... The unit is seconds, heat transfer power The unit is watt.

[0102] Based on the calibrated relationship between the first temperature difference and the first water supply side heat transfer power, and the relationship between the second corrected temperature difference and the second water supply side heat transfer power, the second water supply side heat transfer power is retrieved and multiplied by the duration of the second sampling period to obtain the water supply side heat transfer loss. The water supply side heat transfer loss is the amount of heat transferred. . Among them, heat transfer The unit is joules. Second corrected temperature difference. When the heat transfer is less than or equal to zero, the heat transfer is less than or equal to zero. Take zero.

[0103] The actual calibration tables for temperature difference and heat transfer are established according to the water supply flow rate range, evaporation interface salt concentration range, incident irradiation intensity range, and salt crystal state. Each calibration row records the water supply flow rate, evaporation interface salt concentration, incident irradiation intensity, salt crystal state, surface temperature, water supply side temperature, reflux liquid mass, reflux liquid temperature rise, sampling time, and heat transfer power. The heat transfer power is calculated using the relationship between reflux liquid mass, reflux liquid specific heat capacity, reflux liquid temperature rise, and sampling time in this embodiment.

[0104] During formal testing, only calibration data consistent with the current water supply flow range, salt crystal state, evaporation interface salt concentration range, and incident irradiance intensity range are selected. When the current temperature difference is between adjacent calibration temperature differences, the heat transfer power is determined by linear interpolation of adjacent calibration points; when the current temperature difference exceeds the corresponding calibration range, the heat transfer calibration under that condition is repeated.

[0105] In one feasible implementation, step S150, which determines the interfacial evaporation heat consumption based on the amount of water lost through evaporation, the solution temperature, and the salt concentration at the evaporation interface, includes: Select the evaporation water loss, solution temperature, and salt concentration at the evaporation interface corresponding to the collection period when the salt crystals are not covered from the detection data; Interfacial evaporation heat consumption is the heat consumption of evaporation. Evaporation loss is the amount of water lost. The solution temperature is the solution temperature. The evaporation interface salt concentration is the interface salt concentration. Evaporation consumes heat The unit is joules, water loss The unit is kilogram, and the solution temperature is... The unit is degrees Celsius, and the interfacial salt concentration is... The unit is grams per liter.

[0106] In practice, the collection period during which the salt crystals are not covered is selected based on the status markers of S130. Water loss. Using the calculation results from S120, the solution temperature The average value of the interface salt concentration was obtained by using a temperature sensor at a fixed depth within the evaporation unit during the data acquisition period. The average value for the acquisition period was obtained using a miniature conductivity probe. All three data points used the same timing reference and corresponded to the same acquisition period.

[0107] Six sets of data were acquired at 10-second intervals within each 60-second acquisition period. The average of the six sets of solution temperature data was calculated to obtain the solution temperature. The average of the six sets of evaporation interface salt concentration data was calculated to obtain the interface salt concentration. The total water loss is obtained by summing the water loss from the six groups of evaporation. Water loss Convert to kilograms and then use in subsequent calculations.

[0108] Based on the solution temperature, the first latent heat of vaporization is determined from the preset relationship between temperature and latent heat of vaporization of water. The first latent heat of vaporization is the first latent heat. First latent heat For pure water at solution temperature The latent heat of vaporization per unit mass is calculated. The relationship between temperature and latent heat of vaporization is established using a table consisting of temperature nodes and latent heat nodes, where the temperature nodes cover the solution temperature during the evaporation detection process. The range of variation.

[0109] In practice, a table relating temperature to the latent heat of vaporization of water should be established beforehand based on the thermal properties of water or calorimetric calibration results. Solution temperature When the temperature node matches the one in the table, directly read the corresponding first latent heat. Solution temperature When located between two adjacent temperature nodes, linear interpolation is used to determine the first latent heat. Solution temperature When the data exceeds the range in the table, supplement the latent heat of vaporization data of the corresponding temperature node, instead of directly using the boundary node as a substitute.

[0110] The salt concentration at the evaporation interface is compared with the preset reference salt concentration to obtain the salt concentration deviation, and the corresponding salinity correction coefficient is determined according to the preset salt concentration range in which the salt concentration deviation is located. The preset reference salt concentration is the reference concentration. Salt concentration deviation is concentration deviation The salinity correction factor is the correction factor. Reference concentration The unit is grams per liter, concentration deviation The unit is grams per liter, and the correction factor is... Dimensionless numerical value. Reference concentration. The value can be zero grams per liter, or it can be the initial salt concentration of the solution before it enters the evaporation unit. Correction factor. It is used to characterize the degree of change in the latent heat of vaporization of highly saline concentrated seawater or brackish water relative to pure water.

[0111] In practice, multiple sets of calibration solutions with the same salt composition as the solution to be treated are used for preliminary calibration. Each calibration solution covers a different salt concentration range, and the latent heat of vaporization per unit mass of calibration solution is measured at the same temperature. The ratio of the latent heat of vaporization of the calibration solution to that of pure water at the same temperature is used as a correction factor. According to concentration deviation The calibration results are arranged from low to high to form the concentration deviation range and correction factor. The corresponding relationship table. Current concentration deviation. When the concentration falls within a certain salt concentration deviation range, select the correction factor corresponding to that range. Current concentration deviation When located between two adjacent intervals, the correction factor of the adjacent intervals is used. Perform linear interpolation.

[0112] The first latent heat of vaporization is corrected using a salinity correction coefficient to obtain the second latent heat of vaporization. The heat consumption of interfacial evaporation is then calculated based on the product of the water loss due to evaporation and the second latent heat of vaporization.

[0113] The second latent heat of vaporization is the second latent heat. Second latent heat To take into account the interfacial salt concentration The latent heat of vaporization per unit mass after evaporation. Heat consumed during evaporation. Water loss during the sampling period With the second latent heat The product of these, measured in joules, maintains the same dimensions as incident light energy, light energy loss, and heat transfer loss on the water supply side.

[0114] , Among them, the first latent heat The unit is joules per kilogram, and the second latent heat... The unit is joules per kilogram, and the correction factor is... The value is dimensionless, representing water loss. The unit is kilogram, and the heat consumed during evaporation. The unit is joules. In practice, this is determined based on the current concentration deviation. The correction factor is determined within the interval. Correction coefficient With the first latent heat Multiplying them together yields the second latent heat. Then the second latent heat Water loss during the collection period Multiplying them together gives the heat consumed by evaporation. .

[0115] In the same formal test, the reference concentration Cb is fixed as the initial salt concentration of the solution to be treated before it enters the evaporation unit. The reference concentration Cb is set to zero only for the preliminary calibration of the latent heat of vaporization of pure water, and not for the formal test of high-salinity concentrated seawater or brackish water.

[0116] Salinity correction factor calibration uses a calibration solution with the same salt composition as the solution to be treated. The actual calibration table records the concentration deviation, solution temperature, latent heat of vaporization of the calibration solution, latent heat of vaporization of pure water at the same temperature, and the salinity correction factor. During formal testing, first select the correction factor corresponding to the concentration deviation in the temperature calibration row that is the same as or adjacent to the current solution temperature, and then perform linear interpolation on the calibration data of adjacent concentration deviations and adjacent temperatures. If the concentration deviation or solution temperature exceeds the calibration range, supplement with actual calibration data.

[0117] S160. During the collection period when the salt crystals are not covered, the photothermal conversion efficiency is calculated based on the incident irradiance, light energy loss, heat transfer loss on the water supply side, and heat consumption from interface evaporation.

[0118] Incident light energy is the light energy reaching the light-receiving area during the collection period. Effective absorbed light energy is the incident light energy minus light energy loss. Photothermal conversion heat is the sum of interfacial evaporation heat loss and water supply side heat transfer loss. Photothermal conversion efficiency is the ratio of photothermal conversion heat to effective absorbed light energy.

[0119] In practice, the collection periods in the salt crystal-uncovered state are selected according to the state markers in S130, and the incident irradiance, light energy loss, water supply side heat transfer loss, and interface evaporation heat consumption are extracted from the corresponding detection data of the same collection period or with the same light-receiving area and the same collection duration. The incident light energy, effectively absorbed light energy, and photothermal conversion heat are calculated in sequence to finally obtain the photothermal conversion efficiency.

[0120] In one feasible implementation, step S160, during the collection period when the salt crystals are not covered, calculates the photothermal conversion efficiency based on the incident irradiance, light energy loss, heat transfer loss on the water supply side, and heat consumption from interfacial evaporation, including: Determine the light-receiving area and collection duration corresponding to the collection period when the salt crystals are not covered, and select the incident irradiance, light energy loss, water supply side heat transfer loss and interface evaporation heat consumption corresponding to the collection period from the detection data; The light-receiving area is the light-receiving area Light-receiving area The projected area of ​​the photothermal conversion material, measured in S110 under simulated sunlight illumination, is expressed in square meters. The data acquisition duration is the sampling duration. The unit is seconds. The average incident radiation intensity during the data collection period is the average radiation intensity. The unit is watts per square meter. Light energy loss is the light energy loss... The heat loss on the water supply side is the amount of heat transferred. The heat consumed by interfacial evaporation is the heat consumed by evaporation. Light energy loss Heat transfer and evaporation heat consumption The units are all joules.

[0121] In practice, the target acquisition period is determined based on the marking results of the uncovered salt crystal state in S130. The average incident irradiance is obtained by averaging the incident irradiance at each acquisition time within the target acquisition period. Select the light energy loss corresponding to the target acquisition period from the calculation results of S150. Heat transfer and evaporation heat consumption Light energy loss When the reflection loss ratio corresponding to the target acquisition period is zero, the light energy loss is... Take zero.

[0122] The incident light energy during the collection period is calculated by multiplying the incident irradiance, the light-receiving area, and the collection time. The incident light energy is the incident energy. , representing average irradiance In the light-receiving area Up continuous sampling duration The total input light energy, measured in joules.

[0123] Among them, the average irradiance The unit is watts per square meter, and the area receiving light is... The unit is square meters, and the sampling time is... The unit is seconds, and the incident energy is... The unit is joule.

[0124] In practice, the average irradiance during the target data collection period will be used. Light-receiving area and sampling duration Multiply to obtain the incident energy Light-receiving area The sampling time remains constant throughout the entire testing process. With the selection of light energy loss Heat transfer and evaporation heat consumption The corresponding data collection time is consistent.

[0125] The effective absorbed light energy is calculated based on the difference between the incident light energy and the light energy loss. Effective absorption of light energy is effective energy. , representing incident energy Deducting light energy loss The light energy that can be used for photothermal conversion is measured in joules.

[0126] Among them, incident energy and light energy loss The units are all joules, effective energy. The unit is joule.

[0127] In practical implementation, the light energy loss From incident energy After deducting from the middle, the effective energy is obtained. Effective energy If the energy data is less than or equal to zero, it is determined that the energy data of the current acquisition period does not meet the calculation conditions for photothermal conversion efficiency, and the corresponding detection data is re-acquired.

[0128] The heat loss from interfacial evaporation and the heat loss from water supply are added together to obtain the photothermal conversion heat. The photothermal conversion efficiency is determined by calculating the ratio of the photothermal conversion heat to the effective absorbed light energy.

[0129] Photothermal conversion heat is the heat of conversion , convert heat This represents the sum of heat loss due to interfacial evaporation after the photothermal conversion material absorbs light energy and heat loss due to water supply, expressed in joules. Photothermal conversion efficiency is the conversion efficiency. Conversion efficiency It is a dimensionless numerical value.

[0130] , Among them, evaporation consumes heat. Heat transfer , conversion of heat and effective energy The units are all joules, and the conversion efficiency is... This is a dimensionless value. When expressing conversion efficiency as a percentage, the conversion efficiency will be... Multiply by 100%.

[0131] In practice, the heat consumed by evaporation will be used to implement this. With heat transfer Add them together to obtain the heat of conversion. Then convert heat Divided by effective energy To obtain the conversion efficiency By performing calculations under uncovered salt crystal conditions, the interference of reflection and interfacial mass transfer variations caused by continuous salt crystal capping layers on the basic efficiency calculation results can be avoided.

[0132] During the continuous evaporation monitoring of high-salinity, concentrated seawater, a target collection period in a salt crystal-free state is determined based on continuously collected data. The average irradiance during the target collection period is then extracted. Light-receiving area Sampling duration Light energy loss Heat transfer and evaporation heat consumption And calculate the incident energy in sequence. Effective energy , conversion of heat and conversion efficiency .

[0133] By repeating the aforementioned calculations for different periods of time when the salt crystals are not covered, multiple conversion efficiencies can be obtained. The conversion efficiencies The arithmetic mean is calculated to obtain the photothermal conversion efficiency of the photothermal conversion material under the current testing conditions of high salinity concentrated seawater or brackish water.

[0134] The photothermal conversion efficiency testing method for photothermal conversion materials provided in this application continuously identifies the states of salt crystal coverage, formation, coverage, and dissolution, thus correlating efficiency calculations with specific material surface states and avoiding data conflation between different crystallization states. Furthermore, by sequentially changing the water supply flow rate and incident irradiance within the same salt crystal formation to dissolution cycle, the influence of changes in water supply conditions and illumination conditions on the test data can be separated, and the heat transfer loss on the water supply side, the light energy loss caused by salt crystal coverage, and the heat consumption due to interfacial evaporation can be determined separately. Calculating the photothermal conversion efficiency based on the data collection period under the salt crystal coverage state reduces interference caused by salt enrichment, salt crystal deposition, and changes in operating state, improving the accuracy, stability, and comparability of photothermal conversion efficiency test results under high-salt conditions.

[0135] For the same photothermal conversion material, the same salt composition, the same initial salt concentration, the same light-receiving area, the same initial water supply flow rate, and the same initial incident irradiance, at least three detection cycles were independently completed for the period of collecting data in the salt crystal uncovered state. For each detection cycle, the salt crystal state transition time, reflection spectrum, water supply flow rate, incident irradiance, evaporation water loss, heat transfer loss on the water supply side, interfacial evaporation heat consumption, light energy loss, and conversion efficiency were recorded.

[0136] Under the same test object and environmental conditions, a control test was conducted by calculating the efficiency using the water loss per unit area of ​​light-receiving area over a fixed time period, combined with the incident irradiance and latent heat of vaporization. The efficiency values, arithmetic mean, and sample standard deviations for both the control test and the test in this application were recorded. The actual test report lists the photothermal conversion material number, salt composition of the solution to be treated, initial salt concentration, solution temperature, light-receiving area, water supply flow rate, incident irradiance, sampling time, and all efficiency values.

[0137] Figure 4 This is a schematic diagram of a specific embodiment of a photothermal conversion efficiency detection system for photothermal conversion materials provided in this application, with reference to... Figure 4 The system may include: Recording module 410 is used to place the photothermal conversion material at the liquid surface of the evaporation unit so that the light-receiving surface is above the liquid surface, evaporate under simulated sunlight and continuous water supply and record the incident irradiance. The data acquisition module 420 is used to continuously acquire detection data, including reflectance spectrum, temperature distribution of the light-receiving surface, water supply side temperature, water supply volume, solution mass change, solution temperature and salt concentration at the evaporation interface. The amount of water lost through evaporation is determined based on the water supply volume and solution mass change. The determination module 430 is used to determine the salt crystal uncovered state, salt crystal formed state, salt crystal covered state, and salt crystal dissolved state based on the continuously collected reflectance spectrum and the salt concentration at the evaporation interface. The acquisition module 420 is also used to determine the target time based on the rate of change of the reflection spectrum and the salt concentration at the evaporation interface during the cycle from the salt crystal formation state to the salt crystal dissolution state. Starting from the target time, the water supply flow rate is changed while keeping the incident irradiance constant, and then the incident irradiance is changed while keeping the water supply flow rate constant. Data is collected before and after each change. The determination module 430 is also used to determine the heat transfer loss on the water supply side based on the temperature distribution of the light-receiving surface before and after the change in water supply flow rate, the temperature on the water supply side and the amount of water loss due to evaporation, to determine the light energy loss caused by salt crystal coverage based on the reflection spectrum before and after the change in incident irradiance intensity, and to determine the heat consumption of interfacial evaporation based on the amount of water loss due to evaporation, the solution temperature and the salt concentration at the evaporation interface. The calculation module 440 is used to calculate the photothermal conversion efficiency based on the incident irradiance, light energy loss, water supply side heat transfer loss, and interface evaporation heat consumption during the collection period when the salt crystal is not covered.

[0138] The photothermal conversion efficiency detection system of the photothermal conversion material in this application embodiment is used to implement the aforementioned photothermal conversion efficiency detection method of the photothermal conversion material. Therefore, the specific implementation of the photothermal conversion efficiency detection system of the photothermal conversion material can be found in the embodiment section of the photothermal conversion efficiency detection method of the photothermal conversion material above. The specific implementation can be referred to the description of the corresponding embodiment, and will not be repeated here.

[0139] Figure 5 A schematic diagram of the hardware structure of an electronic device provided in one embodiment of this application is shown.

[0140] The electronic device may include a processor 510 and a memory 520 storing computer program instructions.

[0141] Specifically, the processor 510 may include a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits that can be configured to implement the embodiments of this application.

[0142] Memory 520 may include mass storage for data or instructions. For example, and not limitingly, memory 520 may include a hard disk drive (HDD), floppy disk drive, flash memory, optical disk, magneto-optical disk, magnetic tape, or Universal Serial Bus (USB) drive, or a combination of two or more of these. Where appropriate, memory 520 may include removable or non-removable (or fixed) media. Where appropriate, memory 520 may be internal or external to the integrated gateway disaster recovery device. In a particular embodiment, memory 520 is non-volatile solid-state memory.

[0143] Memory may include read-only memory (ROM), random access memory (RAM), disk storage media devices, optical storage media devices, flash memory devices, and electrical, optical, or other physical / tangible memory storage devices. Therefore, typically, memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the method according to the first aspect of this disclosure.

[0144] The processor 510 reads and executes computer program instructions stored in the memory 520 to implement the photothermal conversion efficiency detection method for any of the photothermal conversion materials in the above embodiments.

[0145] In one example, the electronic device may also include a communication interface 530 and a bus 540. Wherein, such as Figure 5 As shown, the processor 510, memory 520, and communication interface 530 are connected through bus 540 and complete communication with each other.

[0146] Communication interface 530 is primarily used to enable communication between modules, devices, units, and / or equipment in the embodiments of this application. Bus 540 includes hardware, software, or both, that couples components of the online data traffic metering device together. For example, and not limitingly, the bus may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), HyperTransport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an Infinite Bandwidth Interconnect, a Low Pin Count (LPC) bus, a memory bus, a Microchannel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local (VLB) bus, or other suitable buses, or combinations of two or more of these. Where appropriate, bus 540 may include one or more buses. Although specific buses are described and illustrated in the embodiments of this application, this application contemplates any suitable bus or interconnect.

[0147] The electronic device can execute the photothermal conversion efficiency detection method of the photothermal conversion material in the embodiments of this application, thereby realizing the photothermal conversion efficiency detection method of the photothermal conversion material described in conjunction with the accompanying drawings.

[0148] It should be clarified that this application is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of this application is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of this application.

[0149] The functional blocks shown in the above-described structural diagram can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this application are programs or code segments used to perform the required tasks. Programs or code segments can be stored on a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried on a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, etc. Code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0150] It should also be noted that the exemplary embodiments mentioned in this application describe methods or systems based on a series of steps or apparatus. However, this application is not limited to the order of the above steps; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0151] The aspects of this application have been described above with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It should be understood that each block in the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that these instructions, executable via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions / actions specified in one or more blocks of the flowchart illustrations and / or block diagrams. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field-programmable logic circuit. It is also understood that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can also be implemented by dedicated hardware performing the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions.

[0152] The above provides a detailed description of the photothermal conversion efficiency detection method, system, and electronic equipment for photothermal conversion materials provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and its core ideas. It should be noted that those skilled in the art can make various improvements and modifications to this application without departing from its principles, and these improvements and modifications also fall within the protection scope of this application.

Claims

1. A method for detecting the photothermal conversion efficiency of a photothermal conversion material, characterized in that, include: The photothermal conversion material was placed at the liquid surface of the evaporation unit so that the light-receiving surface was above the liquid surface. Evaporation was carried out under simulated sunlight and continuous water supply, and the incident irradiance was recorded. Continuous collection of detection data, including reflectance spectrum, temperature distribution of the light-receiving surface, water supply side temperature, water supply volume, solution mass change, solution temperature and salt concentration at the evaporation interface, and determination of water loss by evaporation based on water supply volume and solution mass change; Based on the continuously collected reflectance spectra and salt concentration at the evaporation interface, the states of salt crystal uncovered, salt crystal formed, salt crystal covered, and salt crystal dissolved were determined. During the cycle from salt crystal formation to salt crystal dissolution, the target time is determined based on the rate of change of salt concentration at the evaporation interface and the reflection spectrum. Starting from the target time, the incident irradiation intensity is kept constant while the water supply flow rate is changed, and then the incident irradiation intensity is kept constant while the water supply flow rate is changed. The detection data is collected before and after each change. The heat transfer loss on the water supply side is determined based on the temperature distribution of the light-receiving surface before and after the change in water supply flow rate, the temperature on the water supply side, and the amount of water lost through evaporation. The light energy loss caused by salt crystal coverage is determined based on the reflection spectrum before and after the change in incident irradiance intensity. The heat consumption of interfacial evaporation is determined based on the amount of water lost through evaporation, the solution temperature, and the salt concentration at the evaporation interface. During the collection period when the salt crystals are not covered, the photothermal conversion efficiency is calculated based on the incident irradiance, light energy loss, heat transfer loss on the water supply side, and heat consumption from interface evaporation.

2. The method for detecting the photothermal conversion efficiency of the photothermal conversion material according to claim 1, characterized in that, The solution within the evaporation unit is high-salinity concentrated seawater or brackish water; the method further includes: Before the target time, based on the rate of change of salt concentration at the evaporation interface, the change in reflection intensity within a predetermined band, and the change in evaporation water loss, the proportion of change in water supply flow rate and the proportion of change in incident irradiance intensity from the target time are determined. The predetermined band is a band selected from the acquisition range of the reflection spectrum and remains unchanged during a cycle from salt crystal formation to salt crystal dissolution. Starting from the target time, the water supply flow rate is changed according to the change ratio of the water supply flow rate, and the incident radiation intensity is changed according to the change ratio of the incident radiation intensity.

3. The method for detecting the photothermal conversion efficiency of the photothermal conversion material according to claim 2, characterized in that, The step of determining the proportion of change in water supply flow rate and the proportion of change in incident radiation intensity from the target time based on the rate of change of salt concentration at the evaporation interface, the change in reflection intensity within a predetermined band, and the change in evaporation water loss includes: The rate of change of salt concentration at the evaporation interface, the change of reflection intensity within the predetermined band, and the change of water loss due to evaporation are compared with their respective preset ranges. If the change in reflection intensity within the predetermined band exceeds the corresponding preset range, and the change in evaporation loss does not exceed the corresponding preset range, then the absolute value of the change ratio of incident irradiance intensity is made greater than the absolute value of the change ratio of water supply flow. If the change in the amount of water lost through evaporation exceeds the corresponding preset range, and the change in the reflection intensity within the predetermined band does not exceed the corresponding preset range, then the absolute value of the change ratio of the water supply flow rate is made greater than the absolute value of the change ratio of the incident radiation intensity. If the rate of change of the salt concentration at the evaporation interface exceeds the corresponding preset range, and the change in reflection intensity and the change in evaporation water loss within the predetermined band do not exceed the corresponding preset range, then the water supply flow rate and the incident irradiation intensity are increased simultaneously, so that the change ratio of the water supply flow rate and the change ratio of the incident irradiation intensity are both positive.

4. The method for detecting the photothermal conversion efficiency of the photothermal conversion material according to claim 1, characterized in that, The process of determining the salt crystal uncovered state, salt crystal formed state, salt crystal covered state, and salt crystal dissolved state based on continuously collected reflectance spectra and salt concentration at the evaporation interface includes: If, within a continuous acquisition period, the change in reflection intensity of the reflection spectrum within a predetermined band does not exceed a first preset fluctuation threshold, and the change in salt concentration at the evaporation interface does not exceed a second preset fluctuation threshold, then the state is determined to be one where the salt crystals are not covered. If the change in salt concentration at the evaporation interface continues to increase, and the change in reflection intensity increases in two or more consecutive acquisition cycles, then it is determined to be the salt crystal formation state. If the change in reflection intensity remains within a third preset fluctuation range within a preset time period, it is determined to be the salt crystal coverage state; If the change in salt concentration at the evaporation interface decreases, and the difference between the change in reflection intensity and the change in reflection intensity in the uncovered salt crystal state decreases, then the state is determined to be the salt crystal dissolved state.

5. The method for detecting the photothermal conversion efficiency of the photothermal conversion material according to claim 1, characterized in that, The determination of the target time based on the reflectance spectrum and the rate of change of salt concentration at the evaporation interface includes: During the cycle from the salt crystal formation state to the salt crystal dissolution state, the change in reflection intensity of the reflection spectrum within a predetermined wavelength band is determined; If the rate of change of the salt concentration at the evaporation interface continues to increase, and the change in reflection intensity increases in two or more consecutive acquisition cycles, then the acquisition time at which the aforementioned changes are simultaneously met for the first time is determined as the target time.

6. The method for detecting the photothermal conversion efficiency of the photothermal conversion material according to claim 1, characterized in that, The determination of heat transfer loss on the water supply side based on the temperature distribution of the light-receiving surface before and after the change in water supply flow rate, the water supply side temperature, and the amount of water lost through evaporation includes: The average temperature of the first surface is calculated based on the temperature distribution of a predetermined area of ​​the light-receiving surface during the first sampling period, and the average temperature of the second surface is calculated based on the temperature distribution of a predetermined area of ​​the light-receiving surface during the second sampling period. The first sampling period and the second sampling period are respectively located before and after the change in water supply flow rate and have the same duration. A first temperature difference is determined based on the first surface average temperature and the water supply side temperature during the first sampling period, and a second temperature difference is determined based on the second surface average temperature and the water supply side temperature during the second sampling period. The change in water loss is determined based on the evaporation water loss during the first and second sampling periods. The temperature compensation value is determined by using the correspondence between the preset change in water loss and the temperature compensation value. The second temperature difference is then corrected using the temperature compensation value to obtain the second corrected temperature difference. Based on the first temperature difference and the second corrected temperature difference, and using the pre-calibrated correspondence between temperature difference and heat transfer based on water supply flow rate, the heat transfer on the first water supply side and the heat transfer on the second water supply side are determined, and the heat transfer on the second water supply side is determined as the heat transfer loss on the water supply side.

7. The method for detecting the photothermal conversion efficiency of the photothermal conversion material according to claim 1, characterized in that, The determination of light energy loss caused by salt crystal coverage based on the reflectance spectrum before and after the change in incident irradiance includes: Select the target reflectance spectrum before and after the incident irradiance intensity changes while keeping the water supply flow rate constant; The target reflectance spectrum is divided into predetermined bands to obtain the reflectance of the band before and after the change. Using the reflectivity of the corresponding band under the salt crystal-free state as the reference reflectivity, the first reflectivity increment and the second reflectivity increment of the band reflectivity before and after the change relative to the reference reflectivity are determined respectively. The irradiance weight of each predetermined band is determined according to the simulated irradiance intensity distribution of sunlight in the predetermined band. The first reflectance increment and the second reflectance increment are accumulated according to the corresponding irradiance weight to obtain the first reflection loss ratio and the second reflection loss ratio. The reflection loss ratio is determined based on the first reflection loss ratio and the second reflection loss ratio, and the light energy loss caused by the salt crystal coverage is calculated using the reflection loss ratio, the corresponding incident irradiance, the light-receiving area, and the sampling time.

8. The method for detecting the photothermal conversion efficiency of the photothermal conversion material according to claim 1, characterized in that, The determination of interfacial evaporation heat consumption based on evaporation water loss, solution temperature, and evaporation interface salt concentration includes: Select the evaporation water loss, solution temperature, and salt concentration at the evaporation interface from the detection data corresponding to the collection period when the salt crystals were not covered. Based on the solution temperature, a first latent heat of vaporization is determined from a preset relationship between temperature and latent heat of vaporization of water. The salt concentration at the evaporation interface is compared with a preset reference salt concentration to obtain the salt concentration deviation, and the corresponding salinity correction coefficient is determined according to the preset salt concentration range in which the salt concentration deviation is located. The first latent heat of vaporization is corrected using the salinity correction coefficient to obtain the second latent heat of vaporization, and the interfacial evaporation heat consumption is calculated based on the product of the water loss due to evaporation and the second latent heat of vaporization.

9. The method for detecting the photothermal conversion efficiency of the photothermal conversion material according to any one of claims 1 to 8, characterized in that, During the collection period when the salt crystals are not covered, the photothermal conversion efficiency is calculated based on the incident irradiance, light energy loss, heat transfer loss on the water supply side, and heat consumption from interfacial evaporation, including: Determine the light-receiving area and collection duration corresponding to the collection period when the salt crystals are not covered, and select the incident irradiance, light energy loss, water supply side heat transfer loss and interface evaporation heat consumption corresponding to the collection period from the detection data; The incident light energy during the collection period is calculated based on the product of the incident irradiance, the light-receiving area, and the collection duration. The effective absorbed light energy is calculated based on the difference between the incident light energy and the light energy loss. The heat loss from interfacial evaporation and the heat loss from water supply are added together to obtain the photothermal conversion heat. The photothermal conversion efficiency is determined by calculating the ratio of the photothermal conversion heat to the effective absorbed light energy.

10. A photothermal conversion efficiency testing system for photothermal conversion materials, characterized in that, include: The recording module is used to place the photothermal conversion material at the liquid surface of the evaporation unit so that the light-receiving surface is above the liquid surface, and to evaporate and record the incident irradiance under simulated sunlight and continuous water supply. The data acquisition module is used to continuously acquire detection data, including reflectance spectrum, temperature distribution of the light-receiving surface, water supply side temperature, water supply volume, solution mass change, solution temperature and salt concentration at the evaporation interface. The amount of water lost through evaporation is determined based on the water supply volume and solution mass change. The determination module is used to determine the salt crystal uncovered state, salt crystal formed state, salt crystal covered state, and salt crystal dissolved state based on the continuously collected reflectance spectrum and the salt concentration at the evaporation interface. The acquisition module is also used to determine the target time based on the rate of change of the reflection spectrum and the salt concentration at the evaporation interface during the cycle from the salt crystal formation state to the salt crystal dissolution state. Starting from the target time, the water supply flow rate is changed while keeping the incident irradiation intensity constant, and then the incident irradiation intensity is changed while keeping the water supply flow rate constant. The detection data is collected before and after each change. The determination module is also used to determine the heat transfer loss on the water supply side based on the temperature distribution of the light-receiving surface, the water supply side temperature, and the amount of water loss due to evaporation before and after the change in water supply flow rate; to determine the light energy loss caused by salt crystal coverage based on the reflection spectrum before and after the change in incident irradiance intensity; and to determine the heat consumption of interfacial evaporation based on the amount of water loss due to evaporation, the solution temperature, and the salt concentration at the evaporation interface. The calculation module is used to calculate the photothermal conversion efficiency based on the incident irradiance, light energy loss, heat transfer loss on the water supply side, and heat consumption from interface evaporation during the collection period when the salt crystals are not covered.

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