Phase change heat storage material storage life testing and evaluating method, system and equipment based on phase change enthalpy and medium

Abstract

The invention discloses a phase change heat storage material storage life testing and evaluating method, system and equipment based on phase change enthalpy and a medium. The method comprises the steps that the phase change enthalpy at the initial moment before accelerated aging is tested; carrying out an accelerated aging test to obtain multiple groups of phase change enthalpy data; aging reaction rate constants under different aging reaction stages are obtained through fitting; determining an optimal reaction stage; fitting to obtain an aging reaction rate factor at the target temperature; calculating the actual storage life required by the phase change material to attenuate from the initial state to the phase change enthalpy retention rate threshold value at normal temperature; and based on the actual storage life and the target life, judging whether the storage life of the phase change heat storage material meets the requirement or not. According to the invention, the test period can be shortened from several years to dozens of days, and the method is suitable for the fields of aerospace, building energy saving, electronic heat dissipation and the like, and has the advantages of high reliability, strong universality and good operability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material aging life test, in particular to a phase change heat storage material storage life test evaluation method, system, device and medium based on phase change enthalpy. BACKGROUND

[0002] Phase change heat storage materials have become key materials for solving energy supply and demand imbalance due to their energy storage characteristics in the phase change process, but they are prone to aging and heat storage capacity decay during long-term storage, and their storage life needs to be accurately evaluated. Chinese invention patent CN118376565A discloses a phase change heat storage material storage life test evaluation method, which determines whether the storage life of the phase change heat storage material meets the target life by obtaining the temperature control time before the accelerated aging test of the phase change heat storage material, calculating the acceleration factor of the phase change heat storage material according to the Arrhenius equation, calculating the accelerated aging test time of the phase change heat storage material according to the acceleration factor, placing the phase change heat storage material in a forced air drying oven for accelerated aging test, testing the temperature control time after the accelerated aging test of the phase change heat storage material, and comparing the temperature control time change percentage of the phase change heat storage material before and after the accelerated aging test. Although the prior art realizes the evaluation of the storage life of the phase change heat storage material, it still has the following defects: the "temperature control time" is used as the core evaluation index, which cannot directly reflect the heat storage capacity of the phase change heat storage material, and the activation energy is taken as an empirical value and the Boltzmann constant is misused, resulting in low reliability of the life evaluation result. SUMMARY

[0003] In order to at least solve one of the problems existing in the prior art, the present application provides a phase change heat storage material storage life evaluation method based on macro aging reaction scale and k value fitting of multiple sets of temperature data, which realizes "direct, fast and accurate" life determination and is suitable for various phase change heat storage materials.

[0004] The present application provides a phase change heat storage material storage life test evaluation method based on phase change enthalpy, which comprises the following steps: Testing the initial time phase change enthalpy of the phase change heat storage material before the accelerated aging test; Loading the phase change heat storage material into a sealed container and carrying out multiple sets of temperature gradient accelerated aging test to obtain multiple sets of phase change enthalpy data; Based on the initial time phase change enthalpy, normalizing the phase change enthalpy data, and fitting the normalized phase change enthalpy data through reaction kinetics models of different aging reaction orders to obtain aging reaction rate constants under different aging reaction orders ; Determining the best reaction order by fitting the determination coefficient ; Based on the preset use condition temperature , the preset test condition temperature and aging reaction rate constants at different aging reaction orders The aging reaction rate factor at the target temperature was obtained by fitting. ; Based on the reaction kinetic model corresponding to the optimal reaction order, combined with the aging reaction rate factor Compared with the preset phase change enthalpy retention rate threshold Calculate the actual storage life required for a phase change material to decay from its initial state to the phase change enthalpy retention threshold at room temperature. ; Based on actual storage life With target lifespan To determine whether the storage life of phase change thermal storage materials meets the requirements.

[0005] Furthermore, differential scanning calorimetry was used to obtain a heat flow-temperature curve. By integrating the phase transition interval of the heat flow-temperature curve, the enthalpy corresponding to the phase transition peak was obtained, which is the phase transition enthalpy at the initial moment. .

[0006] Furthermore, the sealed container is made of high-pressure resistant materials such as a high-pressure gold-plated crucible to prevent the volatilization or oxidation of the material at high temperatures.

[0007] Furthermore, reaction kinetic models for different aging reaction orders include: The zero-order reaction kinetic model is expressed as follows: ,by" The vertical axis represents time. With the x-axis as the horizontal axis and the intercept set to 1, the slope is... ; The first-order reaction kinetic model is expressed as follows: ,by The vertical axis represents time. Perform an exponential fit on the horizontal axis, with the intercept set to 1, and the absolute value of the slope is... ; The second-order reaction kinetic model is expressed as follows: ,by The vertical axis represents time. The horizontal axis is the slope. .

[0008] Furthermore, the phase change thermal storage material was placed in a sealed container and subjected to multiple sets of accelerated aging tests. Each set of tests was set with multiple temperatures, and the multiple temperature settings in the multiple sets of accelerated aging tests were the same. The fitting determination coefficient was calculated for multiple sets of data at each temperature, and the average value was taken as the goodness of fit of the corresponding reaction order at that temperature. The optimal reaction order of the aging reaction was determined based on the average values ​​of the 0th, 1st, and 2nd order reactions.

[0009] Further, the value of activation energy ranges from 0.5 to 2eV, if the determination coefficient obtained by fitting in the reaction at a lower temperature is less than 0.5, the low reliability data under the test is rejected, only the larger data is used for re-fitting.

[0010] Further, if the best reaction order cannot be determined by calculating the average value of the determination coefficient, the aging reaction rate constant values obtained by fitting different order reactions at each temperature are averaged respectively to obtain the aging reaction rate constant values of 0th, 1st and 2nd order reactions at different temperatures, and the aging reaction rate constant values of 0th, 1st and 2nd order reactions are fitted by Arrhenius equation respectively, and then the fitting determination coefficient at different orders is calculated based on the calculated fitting determination coefficient to determine the best reaction order.

[0011] Further, the aging reaction rate factor at normal temperature is obtained by fitting, wherein the fitting equation used is = (- , and the steps for obtaining the aging reaction rate factor at normal temperature include: making , and combining the aging reaction rate constant at different aging reaction orders, fitting by the fitting equation to obtain the activation energy and the pre-exponential factor ; making , and based on the known activation energy and the pre-exponential factor , fitting by the fitting equation to calculate the aging reaction rate factor at normal temperature.

[0012] Further, the calculation method of the storage life is: when the best reaction order is 0, ; when the best reaction order is 1, ; when the best reaction order is 2, .

[0013] ​This invention provides a system for testing and evaluating the storage life of phase change thermal storage materials based on phase change enthalpy, the system comprising the following modules: The initial phase change enthalpy acquisition module is used to obtain the initial phase change enthalpy of the phase change thermal storage material before the accelerated aging test. A multi-phase change enthalpy acquisition module is used to obtain multiple sets of phase change enthalpy data under multiple temperature gradient accelerated aging tests; The aging reaction rate constant calculation module is used to normalize the phase transition enthalpy data based on the initial phase transition enthalpy, and then fit the normalized phase transition enthalpy data to reaction kinetic models of different aging reaction orders to obtain the aging reaction rate constant for different aging reaction orders. ; The optimal reaction order determination module is used to determine the optimal reaction order by fitting the coefficients of determination. Determine the optimal reaction order; The target aging reaction rate factor calculation module is used to calculate the aging reaction rate factor based on preset operating temperature conditions. Preset test conditions temperature and aging reaction rate constants at different aging reaction orders The aging reaction rate factor at the target temperature was obtained by fitting. ; The actual storage life calculation module is used to calculate the actual storage life based on the reaction kinetic model corresponding to the optimal reaction order, combined with the aging reaction rate factor. Compared with the preset phase change enthalpy retention rate threshold Calculate the actual storage life required for a phase change material to decay from its initial state to the phase change enthalpy retention threshold at room temperature. ; Evaluation module for evaluating actual storage life With target lifespan To determine whether the storage life of phase change thermal storage materials meets the requirements.

[0014] The present invention provides a computer device including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method described herein.

[0015] This invention provides a computer-readable storage medium storing a computer. A program, which, when executed by a processor, implements the method.

[0016] This invention directly fits the aging reaction rate factor using multiple sets of temperature data, thus defining the scale of the aging reaction as macroscopic and reducing computational complexity and error risk.

[0017] The application is suitable for the storage life detection and quality control of phase change heat storage materials in the fields of aerospace (such as spacecraft thermal control systems), building energy saving (such as wall heat storage modules), electronic heat dissipation (such as power battery thermal management) and the like, and is especially suitable for material performance verification in the research and development stage and batch quality screening in the production stage, and has the advantages of high reliability, strong universality and good operability.

[0018] Compared with the prior art, the application has the following beneficial effects: (1) Scale determination, no experience calculation, higher precision: directly fitting value through multiple sets of temperature data, combining with Arrhenius theory to obtain , eliminating the acceleration factor conversion link and avoiding the error introduced by AF, and the evaluation error is less than or equal to 5%.

[0019] (2) Efficiency is improved significantly: in the embodiment, five sets of temperature gradients accelerate aging for only 8 days, combined with life calculation, the overall test period is shortened to 30-50 days, which is much faster than the years of natural aging cycle.

[0020] (3) Strong universality: suitable for organic, inorganic and composite phase change heat storage materials, only the value needs to be adjusted, without changing the test program.

[0021] (4) Simple operation: the equipment used is the laboratory conventional equipment, the data processing can be completed through Excel or Origin, without the need of special software, and it is convenient for industrialization promotion. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a flowchart of a phase change heat storage material storage life test and evaluation method based on phase change enthalpy provided by the embodiment of the application.

[0023] Figure 2 is a 90℃ n1,0 order reaction fitting curve diagram in the embodiment of the application.

[0024] Figure 3 is a 90℃ n1,1 order reaction fitting curve diagram in the embodiment of the application.

[0025] Figure 4 is a 90℃ n1,2 order reaction fitting curve diagram in the embodiment of the application. DETAILED DESCRIPTION

[0026] ​In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. All other embodiments obtained by a person of ordinary skill in the art without creative work based on the embodiments in the present application are within the protection scope of the present application.

[0027] Referring to Figure 1 The method for testing and evaluating the storage life of the phase change heat storage material based on phase change enthalpy provided by the embodiments of the present application comprises the following steps. Step 1: testing the initial phase change enthalpy at the initial moment before the accelerated aging of the phase change heat storage material .

[0028] Differential scanning calorimetry (DSC) is adopted to carry out the test, and the test conditions are strictly controlled to ensure the data repeatability.

[0029] In this step, the initial phase change enthalpy H0 is tested by differential scanning calorimetry (DSC) under a nitrogen atmosphere (to avoid sample moisture absorption or oxidation caused by contact with air, and the sample mass error is controlled within ±0.1 mg), 5-15 mg of sample is weighed and loaded into a sealed container; the nitrogen flow is set to 50-100 mL / min, the heating rate is set to 5-10 ℃ / min, and the heating range covers the phase change temperature interval of the material (from room temperature to 20-30 ℃ above the phase change peak temperature); the enthalpy value corresponding to the phase change peak is obtained by integrating the heat flow-temperature curve obtained by the test, that is, the initial moment phase change enthalpy .

[0030] In one embodiment, the testing step comprises: Sample preparation: under the protection of nitrogen, 5-15 mg of sample (to avoid sample oxidation or moisture absorption) is weighed, loaded into a high-pressure gold-plated crucible and compacted and sealed; Instrument parameters: set the nitrogen flow to 50 mL / min (to exclude oxygen interference), set the heating rate to 5 ℃ / min, and set the heating range to “room temperature to phase change peak temperature + 25 ℃” (to ensure complete capture of the phase change process), and obtain the heat flow-temperature curve by the test; Data processing: integrate the phase change interval of the heat flow-temperature curve by the DSC instrument software to obtain the initial phase change enthalpy (unit: J / g), and take the average of three parallel tests to reduce random errors.

[0031] Step 2: load the phase change heat storage material into a sealed container and carry out a plurality of temperature gradient accelerated aging tests to obtain a plurality of phase change enthalpy data.

[0032] In one embodiment, the relevant conditions and data acquisition of the accelerated aging test include: Sample sealing: The phase change heat storage material is sealed in a high-pressure gold-plated crucible, and the pressure is set to 1.5 N.

[0033] Temperature setting: The sealed phase change heat storage material samples are respectively placed in 5 drying ovens, and the temperatures are set to 50°C, 60°C, 70°C, 80°C, and 90°C (temperature control accuracy ±0.5°C) respectively. Each temperature is set with 2 parallel samples, i.e. 2 parallel experiments are set at each temperature. Data recording: At the same time every day, one set of samples is taken from each drying oven, and the phase change enthalpy is tested according to the DSC conditions in step 1. After testing, the samples are returned to the drying oven for continuous aging. The test is continuously conducted for 8 days, and 9 sets of phase change enthalpy data (t=0~8 days) are obtained at each temperature.

[0034] Step 3: Based on the initial phase change enthalpy, the phase change enthalpy data is normalized, and the normalized phase change enthalpy data is fitted by different aging reaction order kinetic models to obtain the aging reaction rate constant under different aging reaction orders .

[0035] In one embodiment, when data normalization is performed, the normalization value of the 9 sets of phase change enthalpy data at each temperature is calculated , , where is the initial phase change enthalpy, is the phase change enthalpy at time , and if -8 is close to 0, it is replaced by 10 to avoid calculation errors.

[0036] In one embodiment, the reaction kinetics model fitting: the normalized data of the five temperatures are fitted by 0-order, 1-order and 2-order reaction kinetics models respectively: The 0-order reaction kinetics model is , with as the vertical axis, time as the horizontal axis, intercept positioned at 1, and the slope as ; The 1-order reaction kinetics model is , with as the vertical axis, time as the horizontal axis, and the absolute value of the slope as ; The 2-order reaction kinetics model is , with as the vertical axis, time as the horizontal axis, and the slope as .

[0037] Step 4: Determine the coefficient of determination by fitting Determine the best reaction order.

[0038] For the determination of the reaction order, first use the measured normalized data to fit, preliminary determination of the aging reaction order.

[0039] Determine the coefficient of determination by fitting Evaluate the model fitting effect, The closer to 1, the higher the degree of agreement between the model and the data. The expression of the coefficient of determination is:

[0040] For example, the n1 group at 90°C test conditions, is the phase change enthalpy retention rate obtained by testing each day of the group, is the data of the group under the assumption of the fitting straight line corresponding to predicted value, is the arithmetic mean of all measured values. n1, n2 are the phase change enthalpy retention rate test values of two different groups per day at each temperature.

[0041] Calculate the coefficient of determination for n1 and n2 data at each temperature , take the average as the fitting degree of the corresponding reaction order at this temperature, and finally compare the average values of 0 order, 1 order and 2 order reactions, and select the maximum average value as the reaction order of the material aging reaction.

[0042] In one embodiment, if the average values of 0 order, 1 order and 2 order reactions obtained in the initial data normalization result are close, the Arrhenius equation fitting is continued.

[0043] The aging reaction rate constants values (for example, the values obtained by fitting under the assumption of 0 order reaction for n1 and n2 groups at 90°C) are first averaged respectively to obtain the values of 0 order, 1 order and 2 order reactions at five groups of temperatures. The five values obtained by 0 order, 1 order and 2 order reactions are fitted respectively by the Arrhenius equation This fitting will also obtain the fitting equation under three reaction orders, and then the determination coefficients under different orders are calculated. If the reaction order is not determined in the previous step, the The largest group is the reaction order of the actual aging reaction. is the pre-exponential factor, is the activation energy, in KJ / mol, is the gas constant, is the absolute temperature, in K.

[0044] Step 5: Based on the preset use condition temperature , the preset test condition temperature , and the aging reaction rate constant under different aging reaction orders of step 3 , the aging reaction rate factor at the target temperature is obtained by fitting .

[0045] Natural logarithm ( ), linear fitting is performed with “ ” as the vertical axis and “1 / ” as the horizontal axis to obtain the fitting equation =(- .

[0046] In one embodiment, the test condition temperature is first set to 50-90°C (unit: K), the aging reaction rate constant under different aging reaction orders of step 3 , is fitted by the fitting equation =(- to obtain the activation energy and the pre-exponential factor ; on the basis of the known activation energy and the pre-exponential factor , the use condition temperature is set to 20-25°C (unit: K), , the aging reaction rate factor at the target temperature is calculated by the fitting equation =(- .

[0047] Specifically, in one embodiment, the activation energy and the pre-exponential factor are calculated: the activation energy (unit: kJ / mol) is calculated according to the fitting slope ; the pre-exponential factor (unit: 1 / day) is calculated according to the intercept ; Calculation of : the absolute temperature corresponding to the normal temperature is calculated.(20℃ corresponds to 293.15K, 25℃ corresponds to 298.15K) is substituted into the Arrhenius equation to calculate the aging reaction rate factor at room temperature .

[0048] Step 6: According to the reaction kinetics model corresponding to the optimal reaction order, combined with the aging reaction rate factor and the preset phase change enthalpy retention rate threshold , the actual storage life of the phase change material from the initial state to the phase change enthalpy retention rate threshold at room temperature is calculated .

[0049] According to the optimal reaction order determined in step 4, the corresponding kinetic formula is selected to calculate the actual storage life (unit: days, which can be converted to years later): If it is a zero-order reaction: , is the phase change enthalpy retention rate threshold; If it is a first-order reaction: ; If it is a second-order reaction: ; wherein According to the material type, in one embodiment, the organic phase change material (paraffin, fatty acid) =0.90, inorganic phase change material (hydrated salt, molten salt) =0.95, high reliability scenario (such as aerospace) can be increased to 0.92~0.95.

[0050] Step 7: Life qualification determination.

[0051] Compare the actual storage life with the target life : If , it is determined that the material storage life meets the requirements; If , it is determined that the material storage life does not meet the requirements.

[0052] In one embodiment, taking "a certain hydrated salt phase change material (target room temperature (20℃) storage life of 20 years)" as an example, the implementation process of the embodiment implementation method of the present application is described in detail: Test preparation: Material: paraffin phase change heat storage material (phase change temperature 58℃, particle size 20-50 mesh); Equipment: Differential Scanning Calorimeter (Model: DSC F404), air-drying oven (temperature control accuracy ±0.5℃), electronic analytical balance (accuracy 0.1mg), high-pressure gold-plated dry pot (LOZE, volume 27μL, pressure 1.5N); Parameter preset: use condition temperature =20℃ (293K), test condition temperature =95℃ (368K), =20 years.

[0053] Step 1: test initial time phase change enthalpy .

[0054] Sample weighing: weigh 8.2mg of a certain hydrated salt phase change material sample in a nitrogen glove box, high-pressure gold-plated crucible (model: TA Tzero) and press the lid to seal; DSC test: set the nitrogen flow rate to 50mL / min, the heating rate to 5℃ / min, and the temperature range to 30-120℃, and obtain the heat flow-temperature curve by testing; Data calculation: the heat flow-temperature curve shows that the phase change peak temperature is 88.3℃, and the initial phase change enthalpy is obtained by integration =300J / g.

[0055] Step 2: conduct five groups of temperature accelerated aging tests Sample placement: place the high-pressure gold-plated crucible on the crucible rack and place it in the air-drying oven; Temperature setting: the temperatures of the 5 ovens (set at the phase change temperature, select multiple groups with certain intervals) are set to 50℃, 60℃, 70℃, 80℃, and 90℃ respectively, and 2 groups of samples are placed at each temperature; Data recording: take samples to measure phase change enthalpy at 14:00 every day, and obtain 9 groups of data at each temperature within 8 days (example: at 90℃ =0~8 days phase change enthalpy are 298.1, 296.5, 296.7, 294.1, 280.5, 279.0, 261.7, 260.8, and 260.5J / g respectively).

[0056] Step 3: fit the values at five temperatures , =8 days =260.5 / 298.1≈0.873; By assuming method, respectively assume that the reaction is 0 order, 1 order and 2 order reaction, use Arrhenius equation to simulate the 5 groups of The values ​​are linearly fitted, and the coefficient of determination is obtained. (for 0th order reactions) =0.9520, for a first-order reaction =0.9515, for a second-order reaction =0.9509), determining the optimal reaction order as 0; Calculate the optimal reaction order, i.e., the reaction order at 0th order. Value: Aging reaction rate constant at 90℃; k at 90℃. 90 =0.015715 / day; at 80℃, k 80 =0.0049764 / day; at 70℃, k 70 =0.0027887 / day; at 60℃, k 60 =0.000657 / day; at 50℃, k 90 =0.000233 / day.

[0057] Step 4: Derive the aging reaction rate factor at room temperature .

[0058] =(-

[0059] Arrhenius fit: for and ( Fitting the values ​​at 323K, 333K, 343K, 353K, and 363K respectively, yields the equation. = -12259×( +29.597, slope =-12259; Calculate activation energy With pre-exponential factors : =- × =12259×8.314≈101.921kJ / mol, =exp (28.97)≈7.14×10 13 / sky; Derivation of the aging reaction rate factor at room temperature Substitution =298K, thus obtaining =≈-12259x(1 / 298)+29.597=-11.54,k0=0.00000972, that is, 9.72x10^6 / day.

[0060] 4.6 Step 5: Calculate the actual storage life

[0061] The optimal reaction order is 0. =0.95, substitute into the formula =(1-0.95) / 9.72×10 -6 ≈(0.05) / 9.72×10 -6 ≈10375.8119 days ≈28.43 years

[0062] 4.7 Step 6: Determine the result The actual storage life of 28.43 years is greater than the target life of 20 years, indicating that the storage life of the hydrated salt phase change thermal energy storage material meets the requirements.

[0063] The lifespan calculation results can be converted from "days to years" (1 year is calculated as 365 days) for easy comparison with the target lifespan.

[0064] In one embodiment, a system for testing and evaluating the storage life of phase change thermal storage materials based on phase change enthalpy is provided to implement the method provided in the foregoing embodiments. The system includes the following modules: The initial phase change enthalpy acquisition module is used to obtain the initial phase change enthalpy of the phase change thermal storage material before the accelerated aging test. A multi-phase change enthalpy acquisition module is used to obtain multiple sets of phase change enthalpy data under multiple temperature gradient accelerated aging tests; The aging reaction rate constant calculation module is used to normalize the phase transition enthalpy data based on the initial phase transition enthalpy, and then fit the normalized phase transition enthalpy data to reaction kinetic models of different aging reaction orders to obtain the aging reaction rate constant for different aging reaction orders. ; The optimal reaction order determination module is used to determine the optimal reaction order by fitting the coefficients of determination. Determine the optimal reaction order; The target aging reaction rate factor calculation module is used to calculate the aging reaction rate factor based on preset operating temperature conditions. Preset test conditions temperature and aging reaction rate constants at different aging reaction orders The aging reaction rate factor at the target temperature was obtained by fitting. ; The actual storage life calculation module is used to calculate the actual storage life based on the reaction kinetic model corresponding to the optimal reaction order, combined with the aging reaction rate factor. Compared with the preset phase change enthalpy retention rate threshold Calculate the actual storage life required for a phase change material to decay from its initial state to the phase change enthalpy retention threshold at room temperature. ; Evaluation module for evaluating actual storage life With target lifespan To determine whether the storage life of phase change thermal storage materials meets the requirements.

[0065] In one embodiment, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the methods described in the foregoing embodiments.

[0066] In one embodiment, a computer-readable storage medium is provided, the computer-readable storage medium storing a computer program that, when executed by a processor, implements the methods described in the foregoing embodiments.

[0067] Phase change enthalpy, as a direct characteristic parameter of heat storage capacity, exhibits a decay pattern highly correlated with the degree of aging (correlation coefficient > 0.95). This invention embodiment uses five sets of temperature gradient data to fit the aging reaction rate factor. The aging reaction rate factor at room temperature was derived directly using Arrhenius theory. This eliminates the AF conversion step, significantly improving evaluation efficiency and accuracy, and solving the pain points of existing technologies.

[0068] In the aforementioned embodiments of the present invention, multiple sets of data reflecting the remaining heat storage capacity of the phase change thermal storage material are obtained through a certain amount of accelerated aging time testing. Based on the Arrhenius equation and fitting methods, the activation energy Ea and pre-exponential factor A of the target material under the target environmental conditions are obtained to calculate the storage life of the target material. The combination of testing and theory results in a more direct and accurate life determination.

[0069] This invention aims to address the problems of existing phase change thermal energy storage material (PCE) life assessment relying on indirect indicators such as temperature control time and weight change, being susceptible to environmental interference and having low accuracy, and having long natural aging test cycles. This invention uses phase change enthalpy, which directly reflects the material's thermal storage capacity, as the core assessment indicator, and combines differential scanning calorimetry (DSC) with Arrhenius accelerated aging theory to achieve accurate and rapid life assessment.

[0070] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined in this invention may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for testing and evaluating the storage life of phase change thermal storage materials based on phase change enthalpy, characterized in that, Includes the following steps: The initial phase change enthalpy of the phase change thermal storage material before the accelerated aging test. The phase change thermal storage material was loaded into a sealed container, and multiple sets of accelerated aging tests with temperature gradients were carried out to obtain multiple sets of phase change enthalpy data. Based on the initial phase transition enthalpy, the phase transition enthalpy data were normalized, and the normalized phase transition enthalpy data were fitted using reaction kinetic models of different aging reaction orders to obtain the aging reaction rate constants for different aging reaction orders. ; By fitting the coefficient of determination Determine the optimal reaction order; Based on preset usage conditions and temperature Preset test conditions temperature and aging reaction rate constants at different aging reaction orders The aging reaction rate factor at the target temperature was obtained by fitting. ; Based on the reaction kinetic model corresponding to the optimal reaction order, combined with the aging reaction rate factor Compared with the preset phase change enthalpy retention rate threshold Calculate the actual storage life required for a phase change material to decay from its initial state to the phase change enthalpy retention threshold at room temperature. ; Based on actual storage life With target lifespan To determine whether the storage life of phase change thermal storage materials meets the requirements.

2. The method for testing and evaluating the storage life of phase change thermal storage materials based on phase change enthalpy according to claim 1, characterized in that, Differential scanning calorimetry was used to obtain the heat flow-temperature curve. By integrating the phase transition interval of the heat flow-temperature curve, the enthalpy corresponding to the phase transition peak was obtained, which is the phase transition enthalpy at the initial moment. .

3. The method for testing and evaluating the storage life of phase change thermal storage materials based on phase change enthalpy according to claim 1, characterized in that, Reaction kinetic models for different aging reaction orders include: The zero-order reaction kinetic model is expressed as follows: ,by" The vertical axis represents time. With the x-axis as the horizontal axis and the intercept set to 1, the slope is... ; The first-order reaction kinetic model is expressed as follows: ,by The vertical axis represents time. Perform an exponential fit on the horizontal axis, with the intercept set to 1, and the absolute value of the slope is... ; The second-order reaction kinetic model is expressed as follows: ,by The vertical axis represents time. The horizontal axis is the slope. .

4. The method for testing and evaluating the storage life of phase change thermal storage materials based on phase change enthalpy according to claim 1, characterized in that, The phase change thermal storage material was placed in a sealed container and subjected to multiple accelerated aging tests. Each test set multiple temperatures, and the multiple temperature settings in the multiple accelerated aging tests were the same. The fitting determination coefficient was calculated for multiple sets of data at each temperature, and the average value was taken as the goodness of fit of the corresponding reaction order at that temperature. The optimal reaction order of the aging reaction was determined based on the average value of the 0th, 1st and 2nd order reactions.

5. The method for testing and evaluating the storage life of phase change thermal storage materials based on phase change enthalpy according to claim 4, characterized in that, If the optimal reaction order cannot be determined by averaging the fitted coefficients of determination, then the aging reaction rate constant obtained by fitting different reaction orders at each temperature should be used. The values ​​were averaged to obtain the aging reaction rate constants for the 0th, 1st, and 2nd order reactions at different temperatures. The value represents the aging reaction rate constant for the 0th, 1st, and 2nd order reactions. The values ​​are respectively based on the Arrhenius equation We perform a fit, and then calculate the coefficients of determination for different levels. Based on the calculated coefficient of determination Determine the optimal reaction order.

6. The method for testing and evaluating the storage life of phase change thermal storage materials based on phase change enthalpy according to claim 1, characterized in that, The aging reaction rate factor at room temperature was obtained by fitting. The fitting equation used is: =(- The aging reaction rate factor at room temperature was obtained. The steps include: make And combined with the aging reaction rate constant under different aging reaction orders The activation energy is obtained by fitting the equation. With pre-exponential factors ; make At activation energy With pre-exponential factors Based on the known information, the aging reaction rate factor at room temperature is calculated by fitting the equation. .

7. A method for testing and evaluating the storage life of phase change thermal storage materials based on phase change enthalpy according to any one of claims 1-6, characterized in that, Actual storage life The calculation method is as follows: When the optimal reaction order is 0, ; When the optimal reaction order is 1, ; When the optimal reaction order is 2, .

8. A system for testing and evaluating the storage life of phase change thermal storage materials based on phase change enthalpy, characterized in that, For implementing the method of any one of claims 1-7, the system comprises the following modules: The initial phase change enthalpy acquisition module is used to obtain the initial phase change enthalpy of the phase change thermal storage material before the accelerated aging test. A multi-phase change enthalpy acquisition module is used to obtain multiple sets of phase change enthalpy data under multiple temperature gradient accelerated aging tests; The aging reaction rate constant calculation module is used to normalize the phase transition enthalpy data based on the initial phase transition enthalpy, and then fit the normalized phase transition enthalpy data to reaction kinetic models of different aging reaction orders to obtain the aging reaction rate constant for different aging reaction orders. ; The optimal reaction order determination module is used to determine the optimal reaction order by fitting the coefficients of determination. Determine the optimal reaction order; The target aging reaction rate factor calculation module is used to calculate the aging reaction rate factor based on preset operating temperature conditions. Preset test conditions temperature and aging reaction rate constants at different aging reaction orders The aging reaction rate factor at the target temperature was obtained by fitting. ; The actual storage life calculation module is used to calculate the actual storage life based on the reaction kinetic model corresponding to the optimal reaction order, combined with the aging reaction rate factor. Compared with the preset phase change enthalpy retention rate threshold Calculate the actual storage life required for a phase change material to decay from its initial state to the phase change enthalpy retention threshold at room temperature. ; Evaluation module for evaluating actual storage life With target lifespan To determine whether the storage life of phase change thermal storage materials meets the requirements.

9. A computer device, comprising a memory, a processor, and a system stored in the memory and capable of... A computer program running on the processor is characterized in that, When the processor executes the computer program, it implements the method described in any one of claims 1-7.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the method described in any one of claims 1-7.

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