Medium-high temperature eutectic phase change energy storage material and preparation method thereof
By preparing eutectic phase change materials by mixing adipic acid and sebacic acid in a specific ratio, the problem of high melting point or low latent heat value of existing fatty acid materials in medium and high temperature applications is solved, and efficient medium and high temperature thermal energy storage and management is achieved.
Patent Information
- Application Number
- CN202511528930.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-24
- Publication Date
- 2026-01-13
AI Technical Summary
Existing fatty acid phase change materials have problems with excessively high melting points or low latent heat values in medium and high temperature applications. In particular, the adipic acid-sebacic acid system lacks systematic reports and is difficult to meet the industrial application range of 120~140 °C.
A eutectic phase change material was prepared by mixing adipic acid and sebacic acid in a mass ratio of 0.3387:0.6613. The eutectic phase change material was prepared by heating, mixing and stirring, and then naturally cooling, thus avoiding phase separation and maintaining high latent heat value and thermal stability.
The eutectic phase transition temperature was achieved at 124.1 ℃, the phase transition enthalpy was 216.1 J/g, the phase transition temperature drift was less than 2.5 ℃ after 500 thermal cycles, and the phase transition enthalpy decay was less than 10%, making it suitable for medium and high temperature thermal energy storage and management.
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Figure CN121318705A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of novel organic phase change energy storage material preparation and application technology, specifically relating to a medium- and high-temperature eutectic phase change material based on adipic acid and sebacic acid and its preparation method. Background Technology
[0002] Phase change energy storage technology achieves efficient storage and release of thermal energy by absorbing and releasing latent heat during the phase change process of materials. Its unique isothermal energy storage characteristics make it valuable in fields such as building energy conservation, industrial waste heat recovery, renewable energy utilization, and thermal management of electronic devices.
[0003] Currently, phase change materials on the market are mainly divided into two categories: inorganic salts and organic compounds. While inorganic salt materials have high latent heat values, they generally suffer from problems such as strong corrosivity, large supercooling, and severe phase separation. Organic materials (such as fatty acids and dicarboxylic acids) possess characteristics such as non-corrosiveness, high thermal stability, and excellent cycle performance, making them more promising in high-temperature applications such as high-end electronic devices, aerospace, and precision instrument temperature control. However, most single-component fatty acids reported in existing studies have shortcomings such as excessively high melting points or low latent heat values, making it difficult to meet the industrial application range of 120–140 °C.
[0004] Eutectic design can effectively lower the melting point while maintaining a high latent heat value, which is an important approach to solving the aforementioned problems. Aliphatic dicarboxylic acids (such as adipic acid, octanoic acid, and sebacic acid) are abundant, have high latent heat, and excellent thermal stability, making them suitable for constructing medium- and high-temperature eutectic phase change systems. However, existing research mostly focuses on specific dicarboxylic acid or fatty acid combinations, lacking systematic reports on specific ratio ranges, cycle stability, and morphological stability, especially the adipic acid-sebacic acid system, which remains undisclosed. Therefore, there is an urgent need to develop eutectic phase change materials based on dicarboxylic acids. These materials not only possess suitable phase transition temperatures and high latent heat values but also exhibit good thermal stability and application reliability, meeting the needs of medium- and high-temperature thermal energy storage and thermal management. Summary of the Invention
[0005] This invention proposes a binary eutectic phase change material based on adipic acid and sebacic acid, and its preparation method. This method enables effective control of the phase change temperature and enthalpy, and has the advantages of being environmentally friendly, low-cost, easy to operate, and suitable for large-scale production.
[0006] The technical solution of this invention is as follows:
[0007] A medium-to-high temperature eutectic phase change energy storage material is composed of adipic acid and sebacic acid, with a mass ratio of adipic acid to sebacic acid of 0.3387:0.6613. The eutectic phase change temperature is between 122 and 125°C, and the latent heat of phase change is above 210 J / g.
[0008] Furthermore, the eutectic phase transition temperature is 124.1 ℃, and the eutectic phase transition enthalpy is 216.1 J / g.
[0009] After 500 thermal cycles, its phase transition temperature is 121.7°C. o C, with a phase transition enthalpy of 195.4 J / g. The phase transition temperature drift is less than 2.5 ℃, the melting point fluctuation is less than 2%, and the phase transition enthalpy decay is less than 10%.
[0010] This invention also provides a method for preparing a medium-to-high temperature eutectic phase change energy storage material, comprising the following steps:
[0011] Weigh adipic acid and sebacic acid raw materials according to the mass ratio, mix and grind them; place the mixture in a sealed container, heat it at a temperature 10-20°C above the melting point of adipic acid until it is completely melted; after heating until it is completely melted, keep the temperature constant, stir magnetically for 25-30 minutes, take it out, and cool it at room temperature to obtain a eutectic phase change material.
[0012] Applications of adipic acid-sebacic acid eutectic phase change materials in medium and high temperature thermal energy storage and thermal management include, but are not limited to, geothermal energy recovery, mold temperature control, solar-process thermal coupling and industrial waste heat recovery.
[0013] Adipic acid-sebacic acid eutectic phase change materials or their composites are used to achieve temperature control and thermal energy storage in the range of 100 ~ 130 ℃. Specific applications include peak cooling of power devices, temperature buffering of hot pressing molds, and energy recovery of industrial waste heat.
[0014] The advantages of this invention are:
[0015] The adipic acid-sebacic acid eutectic phase change material prepared by this invention has a phase change temperature of 124.1 ℃, making it suitable for thermal management scenarios in medium- and high-temperature electronic devices.
[0016] The adipic acid-sebacic acid eutectic phase change material prepared by this invention is homogeneous, without phase separation, and has a high phase change enthalpy.
[0017] The preparation method provided by this invention is simple, green, environmentally friendly, and pollution-free. Attached Figure Description
[0018] Figure 1 This is a liquidus diagram;
[0019] Figure 2 The DSC results for the adipic acid-sebacic acid eutectic phase change material are shown.
[0020] Figure 3 The figure shows the thermal cycling experimental results of the adipic acid-sebacic acid eutectic phase change material.
[0021] Figure 4 This is a scanning electron microscope image of the adipic acid-sebacic acid eutectic phase change material at 2500x.
[0022] Figure 5 This is a scanning electron microscope image of the adipic acid-sebacic acid eutectic phase change material at 6500x.
[0023] Figure 6 This is a scanning electron microscope image of the adipic acid-sebacic acid eutectic phase change material at 12000x. Detailed Implementation
[0024] To better understand the purpose, structure, and function of this invention, a medium-high temperature eutectic phase change energy storage material of this invention will be described in further detail below with reference to the accompanying drawings.
[0025] This invention provides a medium-high temperature eutectic phase change energy storage material composed of adipic acid and sebacic acid, with a mass ratio of adipic acid to sebacic acid of 0.3387:0.6613.
[0026] A method for preparing a medium-to-high temperature eutectic phase change energy storage material includes the following steps:
[0027] Step 1: Weigh adipic acid and sebacic acid raw materials according to the mass ratio using an analytical balance.
[0028] Step 2: Place the mixture in a sealed container and heat it at a temperature 10-20°C above the melting point of adipic acid (the component with the higher temperature in the binary system) until it is completely melted.
[0029] Step 3: Maintain constant temperature conditions and stir magnetically for 25 to 30 minutes at a speed of 300 r / min to ensure the mixture is fully homogeneous.
[0030] Step 4: Remove the stirred melt and allow it to cool naturally to room temperature to obtain the adipic acid-sebacic acid binary eutectic phase change material.
[0031] By predicting the phase behavior of adipic acid and sebacic acid mixtures using the Schröder equation, their ideal eutectic ratio can be obtained. At this ratio, the melting point of the mixture is lower than that of either individual component (adipic acid or sebacic acid), and the enthalpy of phase transition reaches its maximum. At this point, significant phase separation no longer occurs during melting.
[0032] Because this invention employs an organic binary eutectic system, it exhibits advantages over inorganic phase change materials, such as lower supercooling and less pronounced phase separation, thus eliminating the need for additional nucleating agents like borax or sodium sulfate. Furthermore, both adipic acid and sebacic acid possess excellent thermal stability; their thermal conductivity, heat storage capacity, and latent heat value remain stable during cycling and are not prone to degradation.
[0033] Unless otherwise specified, all raw materials and equipment used in this invention are available from the market.
[0034] The technical solution of the present invention will be further described below through specific embodiments.
[0035] The first step is the design of the phase transition point. By mixing two or more materials in a specific ratio, novel phase change materials with desired melting points and latent heats of phase transition can be designed and developed. The solid-liquid behavior of mixtures of different materials can be modeled using the Gibbs free energy method.
[0036] The equation describing the phase equilibrium of eutectic phase transition materials can be derived from the second law of thermodynamics and phase equilibrium theory:
[0037]
[0038]
[0039] Among them, A and B are the components constituting the eutectic phase change material, and H A and H B The latent heat of phase transition (kJ / kg) of A and B are respectively, and T is the latent heat of phase transition of B. A and T B These are the melting temperatures of A and B, respectively, and X. A and X B These are the mole fractions of A and B, respectively, and G A,ex and G B,ex The excess free enthalpy of A and B are T, respectively. m R is the melting point of the eutectic phase change material, and R is the universal gas constant (R = 8.315 J / (mol·K)).
[0040] Under constant pressure (P), for an ideal binary liquid system composed of components A and B, if no solid solution forms during cooling, the phase transition temperature of the system is related to the solid mole fraction and phase transition enthalpy of component i (A or B) as follows:
[0041]
[0042] Among them, X i It is the solid mole fraction of substance i; H i It is the enthalpy of phase transition of substance i (J / mol); T i R is the phase transition temperature of substance i (unit: K), and R is the universal gas constant (R = 8.315 J / (mol·K)).
[0043] The phase transition enthalpy of eutectic materials can be calculated using the following formula:
[0044]
[0045] Among them, H m It is the phase transition enthalpy (J / mol) of the mixture; C P,L,i It is the liquid-phase isobaric specific heat of substance i; C P,S,i It is the solid-state isobaric specific heat of substance i; since the difference in specific heat between the solid and liquid phases of organic phase change materials is small, the second term in the square brackets on the right side of the equation can be ignored; n = 2.
[0046] Organic eutectic phase change materials were prepared using adipic acid and sebacic acid, without the need for further purification of either. The mass ratio of adipic acid (A) to sebacic acid (B) was set as: M A :M B = 90:10, 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80, 10:90, converted to mole fraction ratios: X A :X B = 86.7:13.3, 74.3:25.7, 62.8:37.2, 52.0:48.0, 42.0:58.0, 32.5:67.5, 23.6:76.4, 15.3:84.7, 7.4:92.6. Based on the above ratios, nine groups of samples can be obtained, through... The eutectic point of the adipic acid / sebacic acid eutectic phase change material was calculated, and the results are as follows: Figure 1 As shown, the horizontal axis represents the mass fraction of adipic acid. At the eutectic point of 125.1 o The optimal mass ratio of adipic acid to sebacic acid is obtained at time C. A :M B = 0.3387:0.6613.
[0047] Furthermore, differential scanning calorimetry (DSC) was used to perform thermal analysis tests on the above nine groups of samples. Figure 2 As shown, the ratio is M A :M B The adipic acid-sebacic acid sample with a ratio of 0.3387:0.6613 showed a single, sharp melting endothermic peak on the heated DSC curve, with an initial temperature (T) of [missing value]. onset The peak temperature (T) was 115.7 ℃. peak The measured melting point was 124.1 °C, and the enthalpy of fusion (ΔH) obtained by baseline integration was 216.1 J / g. Furthermore, the measured melting points of the nine samples were compared with the theoretically predicted melting points calculated using the Schroeder equation, such as... Figure 1As shown, the measured values fit the theoretical values well, indicating that the Schroeder equation can effectively predict the eutectic point of the adipic acid-sebacic acid binary eutectic system, thus verifying the rationality and applicability of the calculation method.
[0048] To evaluate the long-term stability of the eutectic phase change material described in this invention, samples with the optimal proportions were subjected to thermal cycling tests. Specifically, a heating-cooling cycle program was set in the temperature control device, causing the sample to repeatedly rise and fall around the target phase change temperature for a total of 500 cycles. A portion of the sample was removed after every 100 cycles, and its thermophysical parameters were measured using DSC. Figure 3 The test results shown indicate that the DSC curve of the sample remained essentially unchanged after 500 cycles, with a phase transition temperature of 121.7°C. o The phase transition enthalpy is 195.4 J / g, the melting point change is less than 2%, and the phase transition enthalpy decay is less than 10%. These results indicate that the eutectic phase change material described in this invention can maintain a stable structure and properties during long-term repeated phase transitions, exhibiting excellent thermal cycling stability and reliability.
[0049] Furthermore, the pure adipic acid and sebacic acid samples, as well as the eutectic phase change material with the optimal ratio, were characterized using scanning electron microscopy (SEM). Before testing, the samples were cross-sectionally prepared and treated with platinum to enhance conductivity. Figure 4 , Figure 5 , Figure 6 SEM images at magnifications of 2500, 6500, and 12000 show that the microstructure of the eutectic phase change material of this invention is uniform and dense, with no obvious phase separation observed. Compared with the pure component materials, the eutectic sample exhibits better structural uniformity and interfacial bonding at the microscopic level. This indicates that the eutectic phase change material of this invention demonstrates excellent uniformity and stability at the material structure level.
[0050] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.
Claims
1. A medium-to-high temperature eutectic phase change energy storage material, characterized in that, It is composed of adipic acid and sebacic acid, with a mass ratio of adipic acid to sebacic acid of 0.3387:0.6613.
2. The medium-high temperature eutectic phase change energy storage material according to claim 1, characterized in that, The eutectic phase transition temperature of the material is 122 ~ 125°C, and the latent heat of phase transition is above 210 J / g.
3. The medium-high temperature eutectic phase change energy storage material according to claim 1, characterized in that, The eutectic phase transition temperature of the material is 124.1 ℃, and the eutectic phase transition enthalpy is 216.1 J / g.
4. The medium-high temperature eutectic phase change energy storage material according to claim 1, characterized in that, After 500 thermal cycles, the material exhibits a melting point fluctuation of less than 2% and a phase change enthalpy decay of less than 10%.
5. A method for preparing a medium-high temperature eutectic phase change energy storage material as described in any one of claims 1-4, characterized in that, Includes the following steps: Weigh adipic acid and sebacic acid raw materials according to the mass ratio, mix and grind them; place the mixture in a sealed container, heat it at a temperature 10-20°C above the melting point of adipic acid until it is completely melted; after heating until it is completely melted, keep the temperature constant, stir magnetically for 25-30 minutes, take it out, and cool it at room temperature to obtain a eutectic phase change material.
6. The method for preparing a medium-high temperature eutectic phase change energy storage material according to claim 5, characterized in that, The magnetic stirring speed is 300 r / min.
7. An application of a medium-to-high temperature eutectic phase change energy storage material, characterized in that, Temperature control and thermal energy storage are achieved within the range of 100 ~ 130 ℃, including peak cooling of power devices, temperature buffering of hot pressing molds, and energy recovery of industrial waste heat.