Phase change energy storage thermal insulation composite material and preparation method and application thereof

Abstract

The invention discloses a phase-change energy-storage heat-preservation composite material as well as a preparation method and application thereof, and particularly relates to the technical field of heat-preservation composite materials. The phase-change energy-storage heat-preservation composite material comprises the following raw materials in percentage by weight of dry materials: 30%-60% of fly ash, 10%-30% of cement, 5%-20% of lime, 10%-80% of sodium sulfate decahydrate and 0.05%-0.2% of aluminum powder. The method for preparing the phase-change energy-storage heat-preservation composite material comprises the following steps: S1, uniformly dry-mixing the fly ash, the cement, the lime and the sodium sulfate decahydrate; s2, adding water into the dry mixture, and stirring to form slurry; s3, aluminum powder is added into the slurry, and the mixture is poured into a mold after being stirred; s4, standing and aerating to form a porous blank body; s5, the blank body is subjected to maintenance; and S6, cooling and post-processing to obtain a finished product. According to the phase-change energy-storage thermal-insulation composite material and the preparation method thereof provided by the invention, the fly ash is used as a main raw material, the process is simple, and the phase-change energy-storage thermal-insulation composite material has the advantages of excellent phase-change energy storage and temperature regulation functions.

Description

Phase change energy storage and thermal insulation composite materials, their preparation methods and applications Technical Field

[0001] This invention relates to the field of thermal insulation composite materials technology, and in particular to a phase change energy storage thermal insulation composite material, its preparation method and application. Background Technology

[0002] Currently, greenhouses and other agricultural facilities often require a significant amount of additional energy to maintain nighttime temperatures. Their enclosures are mostly constructed using ordinary corrugated steel sheets and polystyrene boards, which have low thermal inertia and cannot effectively cope with diurnal temperature variations. This results in drastic fluctuations in indoor temperature with the external environment, which is detrimental to crop growth.

[0003] Phase change materials, such as sodium sulfate decahydrate, can regulate temperature through latent heat storage, but their direct application in buildings presents technical challenges, including easy leakage due to their liquid state, the need for complex encapsulation, and difficulties in bonding with the substrate. On the other hand, fly ash, as a bulk industrial solid waste, is mostly limited to load-bearing or filling applications in the building materials field, with a single function.

[0004] Therefore, it is necessary to provide a phase change energy storage and thermal insulation composite material, its preparation method, and its application to solve the above-mentioned technical problems. Summary of the Invention

[0005] To overcome the shortcomings of existing building insulation materials with poor temperature regulation capabilities and the difficulty of applying phase change materials in buildings, this paper provides a composite material with excellent phase change energy storage and temperature regulation functions, using fly ash as the main raw material, with simple processing, and a method for its preparation.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a phase change energy storage and heat preservation composite material, the raw materials comprising, by dry weight percentage: 30%-60% matrix material, 10%-30% cement, 5%-20% lime, 10%-80% sodium sulfate decahydrate, and 0.05%-0.2% aluminum powder; wherein the matrix material is at least one of fly ash or clay.

[0007] Preferably, the amount of sodium sulfate decahydrate is 30%-70% of the total weight of the dry material.

[0008] A method for preparing phase change energy storage and thermal insulation composite materials includes the following steps: S1. Dry mixing fly ash or clay, cement, lime, and sodium sulfate decahydrate evenly; S2. Adding water to the dry mixture and stirring to form a slurry; S3. Adding aluminum powder to the slurry, stirring, and then pouring it into a mold; S4. Allowing it to stand and generate gas to form a porous preform; S5. Curing the preform; S6. Cooling and post-treatment to obtain the finished product.

[0009] Preferably, the curing in step S5 is autoclaving, and the curing conditions are: temperature 180-220℃, pressure 1.0-1.5MPa, and time 6-12 hours; the autoclaving is carried out in a saturated steam environment.

[0010] Preferably, the curing described in step S5 is room temperature curing, which means curing in a static environment of 15-35℃ and humidity not less than 60% for 7-28 days.

[0011] Application of phase change energy storage and thermal insulation composite materials in the preparation of building temperature-regulating components.

[0012] Preferably, the building temperature-regulating component is a wall or roof component of a solar greenhouse or agricultural shed.

[0013] Preferably, the outer surface of the building temperature regulating component is covered with a light-absorbing coating.

[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention organically combines industrial solid waste fly ash with low-cost inorganic phase change material sodium sulfate decahydrate, and combines it with cement, lime and other cementing materials and gas generating agent aluminum powder to construct a composite matrix with a porous network structure in situ under autoclaving conditions. This not only effectively encapsulates and fixes sodium sulfate decahydrate, solving the problems of liquid phase leakage and encapsulation in its application, but also enhances the overall thermal insulation performance of the material by utilizing the porous structure, realizing the resource utilization of solid waste.

[0015] (2) The composite material prepared by this invention can effectively utilize the latent heat of phase change of sodium sulfate decahydrate for energy storage and release. During the day, it absorbs solar energy or external heat and stores energy through the phase change process, thus delaying the rise in indoor temperature; at night, it releases the stored heat, slowing down the drop in indoor temperature, thereby significantly regulating the temperature fluctuation inside the building. This solves the problems of low thermal inertia and large diurnal temperature difference in the building envelope of traditional solar greenhouses, agricultural greenhouses and other building structures, providing a more stable temperature environment for crop growth and reducing dependence on additional energy.

[0016] (3) By adjusting the proportions of components such as sodium sulfate decahydrate, this invention can regulate the emphasis on phase change heat storage capacity and thermal insulation performance of the material, forming a product series with graded performance to meet application scenarios with different climatic conditions or temperature regulation requirements. By adding a light-absorbing coating to the outer surface of the component, the solar energy absorption efficiency can be further improved, thereby enhancing the phase change energy storage efficiency and overall temperature regulation capability of the material. Detailed Implementation

[0017] The present invention will be further described below with reference to embodiments. The embodiments of the present invention include, but are not limited to, the following embodiments. Embodiments

[0018] The phase change energy storage and thermal insulation composite material contains the following raw materials by dry weight percentage: 20% fly ash, 6% cement, 3.9% lime, 70% sodium sulfate decahydrate, and 0.1% aluminum powder.

[0019] Weigh out 20% fly ash, 6% cement, 3.9% lime, and 70% sodium sulfate decahydrate according to the specified ratio, and mix them evenly. Add 85% of the total water and stir to form a uniform slurry. Mix 0.1% aluminum powder with the remaining water and add it to the slurry. Stir at high speed for 30-60 seconds and immediately pour it into a mold. Let it stand at room temperature for 2.5 hours to form a porous preform. Place the preform in an autoclave and cure it for 8 hours under saturated steam at 200℃ and 1.2 MPa pressure. After natural cooling, demold and cut or crush to obtain the finished product.

[0020] Performance testing: The building was constructed as an experimental greenhouse.

[0021] Nighttime heat preservation effect: As shown in Table 1-1, the indoor temperature is significantly higher than the outdoor temperature during low-temperature periods.

[0022] Table 1-1: Nighttime Insulation Data for Example 1

[0023] Phase change heat absorption effect during the day: As shown in Table 1-2, when the outdoor temperature rises during the day, the indoor temperature rises slowly due to phase change heat absorption, resulting in a huge negative temperature difference.

[0024] Table 1-2: Daytime Heat Absorption Data

[0025] Overall Results: During the test, the outdoor temperature fluctuated by 10℃ (-2) to 8℃, while the indoor temperature in this example only fluctuated by 6.0℃ (-0.4) to 5.6℃, demonstrating the best temperature stability. Example

[0026] The phase change energy storage and thermal insulation composite material contains the following raw materials by dry weight percentage: 50% fly ash, 15% cement, 4.9% lime, 30% sodium sulfate decahydrate, and 0.1% aluminum powder.

[0027] Weigh out 50% fly ash, 15% cement, 4.9% lime, and 30% sodium sulfate decahydrate according to the specified ratio, and mix them evenly. Add 75% of the total water and stir to form a uniform slurry. Mix 0.1% aluminum powder with the remaining water and add it to the slurry. Stir at high speed for 30-60 seconds and immediately pour it into a mold. Let it stand at room temperature for 2 hours to form a porous preform. Place the preform in an autoclave and cure it for 7 hours under saturated steam at 190℃ and 1MPa pressure. After natural cooling, demold and cut or crush to obtain the finished product.

[0028] Performance testing: The building was constructed as an experimental greenhouse.

[0029] As shown in Table 2-1, the highest indoor temperature in the greenhouse was 8.1℃ and the lowest was -1.2℃ throughout the entire test period.

[0030] Table 2-1: Temperature Extreme Data of Example 2

[0031] As shown in Table 2-2, it exhibits extremely high instantaneous heat preservation ability during low temperature periods.

[0032] Table 2-2: High Thermal Insulation Data

[0033] In this embodiment, the maximum indoor-outdoor temperature difference at night reaches +7.9℃, indicating strong instantaneous heat preservation capabilities. However, the overall indoor temperature fluctuation is 9.3℃ (8.1℃ - (-1.2℃)), which is greater than the 6.0℃ in Example 1. This suggests that while a lower phase change material content can provide better instantaneous heat preservation, its ability to suppress daytime temperature rise is lower, resulting in stronger temperature following throughout the day.

[0034] The comparative example uses a standard aerated concrete block house.

[0035] As shown in Table 3, the indoor temperature changes synchronously with the outdoor temperature, without any temperature control or lag effect.

[0036] Table 3: Comparative Temperature Data

[0037] Its indoor temperature fluctuates as much as 13.4℃, which is basically the same as the outdoor environment, and it does not have an active temperature control function.

[0038] This invention prepares a series of composite materials with different performance focuses by controlling the amount of sodium sulfate decahydrate added. At lower addition levels, the material focuses on providing extremely high instantaneous heat retention; at higher addition levels, the material utilizes a strong latent heat of phase change to achieve temperature stability throughout the day. Both fundamentally overcome the deficiency of traditional building materials in lacking active temperature regulation capabilities. Examples

[0039] This embodiment performs a simple surface heat absorption treatment on the composite material of the present invention, which can further improve its solar energy absorption and phase change energy storage temperature regulation performance.

[0040] Sample preparation: Take the composite material block prepared with the same ratio and process as in Example 1, spray a layer of black acrylic light-absorbing and anti-corrosion paint evenly on its outer surface, and obtain the surface-optimized block after drying.

[0041] Performance testing: The experimental greenhouse was constructed using the above-mentioned optimized blocks, and continuous temperature monitoring was conducted.

[0042] The nighttime heat preservation effect is as follows: As shown in Table 3-1, the indoor and outdoor temperature difference is excellent during the low-temperature period at night.

[0043] Table 3-1: Nighttime Insulation Data

[0044] Daytime heat absorption effect: As shown in Table 3-2, during the daytime outdoor temperature rise period, it also exhibits temperature lag due to phase change heat absorption.

[0045] Table 3-2: Daytime Data

[0046] Comparing the performance of Example 3 and Example 1 during their respective test periods, a clear conclusion can be drawn: applying a light-absorbing coating to the outer surface significantly optimizes the material's performance. Specifically, Example 3 achieved a nighttime thermal insulation temperature difference of +6.9°C to +7.0°C, an improvement of approximately 50% compared to +4.6°C in Example 1. Furthermore, under similar low-temperature conditions, Example 3 was able to maintain a higher indoor temperature plateau. This optimization stems from the black light-absorbing coating enhancing the absorption of solar radiation on the material surface, providing a more sufficient heat source for the embedded phase change material, thereby strengthening the thermal insulation performance.

[0047] This embodiment demonstrates that applying a light-absorbing surface coating is a simple, effective, and non-impairing optimization method that can significantly improve the overall temperature regulation performance of composite materials.

Claims

1. A phase change energy storage and thermal insulation composite material, characterized in that, The raw materials, by dry weight percentage, include: 30%-60% matrix material, 10%-30% cement, 5%-20% lime, 10%-80% sodium sulfate decahydrate, and 0.05%-0.2% aluminum powder; the matrix material is at least one of fly ash or clay.

2. The composite material according to claim 1, characterized in that, The amount of sodium sulfate decahydrate added is 30%-70% of the total weight of the dry material.

3. A method for preparing the phase change energy storage and thermal insulation composite material as described in claim 1 or 2, characterized in that, Includes the following steps: S1. Dry mix fly ash or clay, cement, lime, and sodium sulfate decahydrate evenly; S2. Add water to the dry mixture and stir to form a slurry; S3. Add aluminum powder to the slurry, stir, and pour into a mold; S4. Let stand to generate gas and form a porous preform; S5. Cure the preform; S6. Cool and process to obtain the finished product.

4. The method for preparing phase change energy storage and thermal insulation composite materials according to claim 3, characterized in that, The curing described in step S5 is autoclaving, and the curing conditions are: temperature 180-220℃, pressure 1.0-1.5 MPa, and time 6-12 hours; the autoclaving is carried out in a saturated steam environment.

5. The method for preparing phase change energy storage and thermal insulation composite materials according to claim 3, characterized in that, The curing described in step S5 is room temperature curing, which means leaving the plant to stand for 7-28 days in an environment with a temperature of 15-35℃ and a humidity of not less than 60%.

6. The application of the phase change energy storage and thermal insulation composite material as described in claim 1 or 2 in the preparation of building temperature-regulating components.

7. The application of the phase change energy storage and thermal insulation composite material according to claim 7 in the preparation of building temperature-regulating components, characterized in that, The building temperature-regulating components are wall or roof components of solar greenhouses or agricultural sheds.

8. The application of the phase change energy storage and thermal insulation composite material according to claim 7 in the preparation of building temperature-regulating components, characterized in that, The outer surface of the building temperature regulating component is covered with a light-absorbing coating.

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