A method for testing and evaluating the storage life of a phase change heat storage material

Abstract

The application discloses a kind of testing evaluation methods of phase change heat storage material storage life, comprising the following steps: step 1, test and obtain the temperature control time before phase change heat storage material accelerated aging test;Step 2, according to Arrhenius equation, the acceleration factor of the phase change heat storage material is calculated;Step 3, according to the acceleration factor, the accelerated aging test time of the phase change heat storage material is calculated;Step 4, phase change heat storage material is placed in the accelerated aging test in forced air drying cabinet;Step 5, test the temperature control time after phase change heat storage material accelerated aging test;Step 6, compare the temperature control time change percentage of phase change heat storage material before and after accelerated aging test, if the absolute value of temperature control time change percentage is ≤5%, then determine the storage life of phase change heat storage material meets target life;Otherwise, it does not meet.The testing evaluation method of phase change heat storage material storage life provided by the application is simple, effective.

Description

Technical Field

[0001] This invention relates to the field of material aging life testing technology, and specifically to a method for testing and evaluating the storage life of phase change thermal storage materials. Background Technology

[0002] Non-metallic materials, including phase change thermal storage materials, are widely used in the aerospace and civilian product markets. However, the materials within these products are susceptible to aging, performance degradation, and failure due to factors such as heat, oxygen, and stress, which ultimately affects the overall lifespan of the product. Therefore, testing and evaluating the storage life of materials is crucial for product design and use.

[0003] For non-metallic materials, there are relatively many aging life testing methods and standards for products such as rubber and adhesives, which are widely used in formulation and process improvement and aging resistance screening. However, no testing and evaluation methods for the storage life of materials such as phase change thermal energy storage have been found, and there is an urgent need to find a fast and accurate solution to this problem. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for testing and evaluating the storage life of phase change thermal energy storage materials, which is simple to test and highly effective.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] A method for testing and evaluating the storage life of phase change thermal storage materials includes the following steps:

[0007] Step 1: Test the temperature control time before the accelerated aging test of the phase change thermal storage material;

[0008] Step 2: Calculate the acceleration factor of the phase change thermal storage material based on the Arrhenius equation;

[0009] AF=exp{(Ea / k)·[(1 / Tu)-(1 / Tt)]}

[0010] In the formula, AF is the acceleration factor; Ea is the activation energy in eV; and K is the Boltzmann constant 8.617385 × 10⁻⁶. -5 Tu is the temperature under operating conditions, in K; Tt is the temperature under testing conditions, in K.

[0011] Step 3: Calculate the accelerated aging test time of the phase change thermal storage material based on the acceleration factor;

[0012] Step 4: Place the phase change thermal storage material in a forced-air drying oven for accelerated aging test. Set the temperature inside the forced-air drying oven according to the test conditions and keep it at a constant temperature according to the accelerated aging test time obtained in Step 3.

[0013] Step 5: After the accelerated aging test is completed, the temperature control time of the phase change thermal storage material after the accelerated aging test is tested under the same test conditions as in Step 1.

[0014] Step 6: Compare the percentage change in temperature control time of the phase change thermal storage material before and after the accelerated aging test. If the absolute value of the percentage change in temperature control time is ≤5%, the storage life of the phase change thermal storage material is determined to meet the target life; otherwise, it does not meet the target life.

[0015] Furthermore, in step 2, the activation energy Ea of the phase change thermal storage material is selected in the range of 0.5–0.7 eV.

[0016] Furthermore, when calculating the acceleration factor using the Arrhenius equation, 25°C was used as the operating temperature, and 90–100°C was used as the test temperature.

[0017] Furthermore, in step 3, given the target lifespan, the accelerated aging test time is calculated using the following formula;

[0018] L 试验 =L 目标 / AF

[0019] In the formula, L 试验 To accelerate the aging test time; L 目标 Target lifespan.

[0020] Furthermore, in steps 1 and 5, a ceramic heating element is used to simulate a heat source. The phase change thermal storage material is placed on the ceramic heating element, and the temperature curve change of the heating material is monitored by a temperature recorder to observe the duration in the phase change temperature range, i.e., the temperature control time.

[0021] Furthermore, in step 4, the phase change thermal storage material is first placed in a copper tube and sealed, and then the sealed copper tube is placed in a forced-air drying oven for accelerated aging test.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] The method for testing and evaluating the storage life of phase change thermal storage materials provided by this invention calculates the accelerated aging test time of the phase change thermal storage materials according to the Arrhenius equation, and conducts accelerated aging tests on the samples based on the accelerated aging test time. The storage life of the materials can be quickly evaluated through laboratory accelerated aging tests, and the reaction of the samples in the laboratory accelerated aging test is consistent with that in the natural environment test. It has the advantages of simple testing and good effectiveness. Detailed Implementation

[0024] To enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments.

[0025] Example 1

[0026] This embodiment uses the storage life assessment of 80# paraffin phase change thermal storage material as an example. The target life of this phase change thermal storage material is estimated to be 20 years at 100°C.

[0027] The method for testing and evaluating the storage life of phase change thermal storage materials in this embodiment includes the following steps:

[0028] Step 1: Test the temperature control time before the accelerated aging test of the phase change thermal storage material;

[0029] Specifically, the temperature control time is achieved by using a ceramic heating element to simulate a heat source, placing the phase change thermal storage material on the ceramic heating element, and monitoring the temperature curve changes of the heating material using a temperature recorder to observe the duration within the phase change temperature range.

[0030] Step 2: Calculate the acceleration factor of the phase change thermal storage material based on the Arrhenius equation;

[0031] Temperature is the absolute primary factor affecting product aging and lifespan. Using the Arrhenius equation, which is derived by considering only the thermal acceleration factor effect, to describe the test results, the lifespan prediction is closer to the true value.

[0032] AF=exp{(Ea / k)·[(1 / Tu)-(1 / Tt)]}=exp{[0.68 / (8.617385×10 -5 )]·[1 / (273+25)-1 / (273+100)]}

[0033] In the formula, AF is the acceleration factor; Ea is taken as the general failure value of 0.68 eV, and those skilled in the art can select the value of Ea based on product failure experience; K is the Boltzmann constant 8.617385 × 10⁻⁶. -5 The operating temperature is 25℃, and the test temperature is 100℃.

[0034] The acceleration factor AF≈205 can be obtained;

[0035] Step 3: Calculate the accelerated aging test time of the phase change thermal storage material based on the acceleration factor;

[0036] Specifically, L 试验 =L 目标 / AF

[0037] L目标 If the time is 20 years, then 20 × 365 × 24 = 175200 hours, so we can calculate L. 试验 =L 目标 / AF=175200 / 205=854 hours. That is to say, at a test temperature of 100℃, the accelerated aging test time is 854 hours.

[0038] Step 4: Place the phase change thermal storage material in a forced-air drying oven for accelerated aging test. Set the temperature inside the forced-air drying oven to 100℃ as per the test conditions, and maintain a constant temperature for 854 hours as obtained in Step 3.

[0039] Specifically, the phase change thermal storage material is first placed in a copper tube and sealed, and then the sealed copper tube is placed in a forced-air drying oven for accelerated aging test.

[0040] Step 5: After the accelerated aging test is completed, the temperature control time of the phase change thermal storage material after the accelerated aging test is tested under the same test conditions as in Step 1.

[0041] Specifically, the temperature control time is achieved by using a ceramic heating element to simulate a heat source, placing the phase change thermal storage material on the ceramic heating element, and monitoring the temperature curve changes of the heating material using a temperature recorder to observe the duration within the phase change temperature range.

[0042] Step 6: Compare the percentage change in temperature control time of the phase change thermal storage material before and after the accelerated aging test. If the absolute value of the percentage change in temperature control time is ≤5%, the storage life of the phase change thermal storage material is determined to meet the target life; otherwise, it does not meet the target life.

[0043] Specifically, the absolute value of the percentage change in temperature control time = |(temperature control time after accelerated aging test - temperature control time before accelerated aging test) / temperature control time before accelerated aging test| = 4.1% ≤ 5%, so it is determined that the 80# paraffin phase change thermal storage material in this embodiment meets the target life of 20 years.

[0044] When calculating the accelerated aging test time of phase change thermal storage materials according to the Arrhenius equation, if the initially calculated test time is inappropriate, the temperature under the test conditions can be adjusted and the test time recalculated. Those skilled in the art can choose according to actual needs. As shown in the table below, in this embodiment, when the temperature under the test conditions is increased to 110℃, the recalculated accelerated aging test time is 491.2 hours; when the temperature under the test conditions is decreased to 90℃, the recalculated accelerated aging test time is 1528.6 hours.

[0045] Table 1 shows the corresponding accelerated aging test times under test conditions of 90–110℃.

[0046]

[0047] This invention provides a more reliable method for testing and evaluating the storage life of materials, which effectively solves the problem of testing and evaluating the storage life of materials such as phase change thermal energy storage.

[0048] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for evaluating the storage life of a phase change heat storage material, characterized by, The method comprises the following steps: Step 1, test the temperature control time of the phase change heat storage material before accelerated aging test; Step 2, calculate the acceleration factor of the phase change heat storage material according to the Arrhenius equation; AF = exp{ (Ea / k) · [(1 / Tu) - (1 / Tt)]} In the formula, AF is the acceleration factor; Ea is the activation energy in eV; k is the Boltzmann constant 8.617385 x 10 -5 ; Tu is the temperature under the use condition, in K; Tt is the temperature under the test condition, in K; Step 3, calculate the accelerated aging test time of the phase change heat storage material according to the acceleration factor; Step 4, place the phase change heat storage material in a blast drying oven for accelerated aging test, set the temperature in the blast drying oven according to the temperature under the test condition, and keep the temperature constant for the accelerated aging test time obtained in step 3; Step 5, after the accelerated aging test, test the temperature control time of the phase change heat storage material after the accelerated aging test under the same test condition as in step 1; Step 6, compare the temperature control time change percentage of the phase change heat storage material before and after the accelerated aging test, if the absolute value of the temperature control time change percentage is less than or equal to 5%, it is determined that the storage life of the phase change heat storage material meets the target life; otherwise, it does not meet the target life; In step 2, the activation energy Ea of the phase change heat storage material is selected in the range of 0.5-0.7 eV; The temperature control time refers to that a ceramic heating sheet is used to simulate a heat source, the phase change heat storage material is placed on the ceramic heating sheet, the temperature curve change of the heating material is monitored by a temperature recorder, and the time length in the phase change temperature range is observed.

2. The method for evaluating the service life of a phase change heat storage material according to claim 1, wherein When the acceleration factor is calculated by the Arrhenius equation, 25℃ is used as the temperature under the use condition, and 90-100℃ is used as the temperature under the test condition.

3. The method of claim 1, wherein the phase change heat storage material is a mixture of a first phase change heat storage material and a second phase change heat storage material. In step 3, the target life is known, and the accelerated aging test time is calculated according to the following formula: L 试验 = L 目标 / AF In the formula, L 试验 to accelerate the aging test time; L 目标 is the target life.

4. The method of claim 1, wherein In step 4, the phase change heat storage material is first sealed in a copper pipe, and then the sealed copper pipe is placed in a blast drying oven for accelerated aging test.

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