Passive open-air building temperature regulation and control structure based on composite phase change material and preparation method of passive open-air building temperature regulation and control structure

Abstract

The invention discloses a passive open-air building temperature regulation and control structure based on a composite phase change material and a preparation method of the passive open-air building temperature regulation and control structure. A metal node of the material is strontium ions, N, N '-bis (5-isophthalic acid) naphthalimide is used as a ligand, anthracene and a derivative thereof are used as objects, N, N-dimethylformamide is used as a solvent, and the material is obtained through solvothermal reaction. The material is composed of an electron donor (D) and an electron acceptor (A), and is a strontium-based MOF eutectic with an infinitely extended pi stacked A-D-D-A configuration. The MOF eutectic material has lattice characteristics of a tetragonal crystal system, a space group is I 41 / a, and cell parameters are a = b = 28.42240 (10), c = 13.71600 (10), and alpha = beta = gamma = 90 degrees. Sr-NDI at An has unique wavelength selective photoresponse property: ultraviolet light triggers [4 + 4] dimerization of an object anthracene, red light excites [4 + 2] reaction of anthracene and singlet oxygen, and near-infrared light induces generation of free radicals.

Description

Technical Field

[0001] This invention relates to the field of materials science, and in particular to a composite phase change material for temperature control in outdoor buildings, its preparation method, and its application structure. Background Technology

[0002] With global warming and accelerated urbanization, building energy consumption is becoming increasingly prominent. Open-air buildings, directly exposed to the natural environment, are significantly affected by external climate conditions. During the hot summer months, internal temperatures can become excessively high, while during the cold winter months, they can become excessively low. These large temperature fluctuations not only severely impact the preservation of objects inside the building but also drastically increase the energy consumption of traditional air conditioning, heating, and cooling equipment, leading to significant energy waste. According to relevant statistics, in some hot summer regions, air conditioning and cooling energy consumption accounts for as much as 40%-60% of the total energy consumption of open-air buildings, while in cold winter regions, heating energy consumption also accounts for a considerable proportion.

[0003] Currently, various technologies have been developed to address the temperature control needs of open-air buildings. In terms of insulation materials, traditional materials such as polystyrene boards and rock wool boards are widely used. While they can prevent heat transfer to some extent, the limitations of these traditional materials in terms of insulation durability and environmental friendliness are becoming increasingly apparent with rising demands for energy conservation and environmental protection. For example, polystyrene boards are flammable and prone to aging, while rock wool boards easily generate dust pollution during construction. With ongoing research into temperature control and insulation methods for open-air buildings, phase change materials (PCMs) have attracted widespread attention as a new type of insulation material. PCMs can absorb or release heat through phase change when the temperature changes, thus maintaining a relatively stable internal temperature. Encapsulating PCMs such as paraffin wax in wall cavities or floor pipes, combined with solar collectors, experimental results show that daytime solar heat collection efficiency increases by 20-30%, and nighttime indoor temperature fluctuations decrease by 50%. They can also be applied to cold chain transportation and refrigeration equipment to extend the duration of low-temperature environments during cold chain transportation; experimental results show that the temperature of refrigerated containers can be maintained for 8-12 hours after a power outage. In terms of shading technology, traditional methods such as sunshades and awnings can reduce heat absorption inside open-air buildings by blocking sunlight, but they are insufficient in terms of intelligence and efficiency. In recent years, intelligent shading systems have developed rapidly. These systems can automatically adjust the opening and closing of shading facilities based on parameters such as solar radiation intensity, angle, and indoor temperature to achieve precise shading. For example, some intelligent shading systems using photosensors and temperature sensors can automatically unfold the sunshade curtains when the solar radiation intensity exceeds a certain threshold, effectively reducing the indoor temperature by 2-4℃.

[0004] While current traditional outdoor building temperature control technologies can improve the internal thermal environment to some extent, they still suffer from problems such as high energy consumption, complex structures, poor compatibility, and high costs. Although some technologies have made improvements in energy efficiency, environmental friendliness, and economy, their poor compatibility prevents flexible application across large-scale, diverse scenarios. Therefore, developing efficient, energy-saving, environmentally friendly, economical, and highly compatible outdoor building temperature control products is of significant practical importance and an urgent need. Summary of the Invention

[0005] The purpose of this invention is to address the problems of existing traditional temperature control materials, such as polystyrene boards and rock wool boards, regarding the durability of their thermal insulation performance and environmental friendliness; common protective coatings are prone to aging and peeling over time, gradually reducing their protective performance and potentially leaving harmful substances on building surfaces, causing secondary damage; and intelligent sensor temperature control systems suffer from high energy consumption, high cost, and poor compatibility. This invention proposes a passive outdoor building temperature control structure to achieve temperature regulation inside outdoor buildings.

[0006] The key to solving the above problems lies in designing suitable temperature control structures for different open-air buildings. This can be achieved by designing the outer frame, synthesizing and filling phase change materials, and optimizing the filling chamber parameters. This invention provides a passive temperature control structure for open-air buildings based on composite phase change materials (CPCM), which solves the problems of physical damage and energy consumption caused by temperature fluctuations in open-air buildings, while ensuring the concealment and long-term stability of the temperature control structure. The temperature control structure encapsulates the composite phase change material in a metal array with good thermal conductivity, forming a closed space with the building's environment. This effectively suppresses temperature fluctuations, reduces thermal stress damage, and alleviates energy consumption and pollution to a certain extent. This temperature control structure is characterized by being green and environmentally friendly, using inexpensive raw materials, easy to replace, simple in preparation process, and having long-term weather resistance, providing a new, efficient, and green solution for temperature control in open-air buildings.

[0007] The technical solution of this invention is:

[0008] A passive temperature control structure for open-air buildings based on composite phase change materials is disclosed. This structure comprises three parts: an outer frame, filling material, and a filling chamber. The outer frame is constructed from flame-retardant materials such as high-transmittance acrylic sheets. The filling material is prepared by mixing phase change materials such as paraffin wax with multi-walled carbon nanotubes (MWCNTs). The filling chamber is composed of an array of metals such as aluminum tubes with good thermal conductivity. Utilizing this unique protective structure, the thermal conductivity and thermal cycling stability are improved by optimizing the doping ratio and dispersion process of MWCNTs and phase change materials. Furthermore, considering the actual environmental requirements of the open-air building, the relevant parameters of this structure are optimized to achieve temperature control of the environment in which the building is located. The thermal conductivity enhancer in the filling material has a mass concentration of 0-5 wt%, and the ratio of thermal conductivity enhancer to dispersant is 1:1.7 by mass.

[0009] The outer rectangular frame is made of flame-retardant materials such as high-transmittance acrylic sheet, glass, and polycarbonate. The rectangular structure parameters are: length range of 20-30cm, width of 10-20cm, and height of 5-10cm.

[0010] The thermal energy stored in the phase change materials used are, for example, 150 J / g·K, 220 J / g·K, 244 J / g·K, and 247 J / g·K, corresponding to melting points of 15℃, 22℃, 28℃, and 32℃, respectively, and freezing points of 15℃, 21℃, 28℃, and 32℃, respectively, with a solid density of 0.85 g / cm³. 3 0.78g / cm 3 0.8g / cm 3 0.767 g / cm 3 The liquid density is 0.78 g / cm³. 3 0.765g / cm 3 0.777g / cm 3 0.784 g / cm 3 .

[0011] The filler material is composed of paraffin, a typical phase change material, mixed with multi-walled carbon nanotubes to improve thermal conductivity and oleic acid as a dispersant. The optimal effect of the filler material corresponds to a mass concentration of 3% of the multi-walled carbon nanotubes.

[0012] The filling chamber is composed of an array of metals with good thermal conductivity, such as aluminum, silver, and copper tubes. The array unit has the following structural dimensions: outer radius of 5-30 mm, wall thickness of 0.45-0.8 mm, and length of 4-10 cm. By adjusting the filling chamber parameters, the internal shading and lighting levels of the building can be controlled.

[0013] The method for a passive outdoor building temperature control structure based on composite phase change materials described in this invention is as follows:

[0014] I. Selection of Composite Phase Change Materials

[0015] Matrix material: Paraffin (phase change temperature range 22-35℃, suitable for diurnal temperature differences in most regions);

[0016] Thermal conductivity enhancer: Multi-walled carbon nanotubes (MWCNTs), with a mass concentration of 0-5 wt% (preferably 3 wt%);

[0017] Dispersant: Oleic acid, with an addition ratio of MWCNT:Oleic acid = 1:1.7 (mass ratio);

[0018] II. Preparation of Phase Change Filler Materials

[0019] Melting and mixing: The paraffin wax is completely melted in a constant temperature water bath at 60°C;

[0020] Doping and dispersion: Add MWCNT and oleic acid in proportion, and stir magnetically at a constant temperature for 60 minutes;

[0021] Homogenization process: Ultrasonic water bath oscillation for 90 minutes to ensure uniform dispersion of nanoparticles;

[0022] Molding: After cooling, a uniform composite phase change filler material is obtained;

[0023] III. Fabrication of Passive Outdoor Building Temperature Control Structures

[0024] 1. Select acrylic sheets, glass or polycarbonate flame-retardant materials with a thickness range of 5-10mm, a length range of 20-30cm, and a width range of 10-20cm as the outer material of the protective structure, for subsequent embedding into the original protective structure or splicing of multiple structures.

[0025] 2. Select two rectangular acrylic, glass, or polycarbonate sheets with a thickness of 5-10mm, a length of 20-30cm, and a width of 10-20cm to fix the metal tube array and ensure the light transmittance of this structure.

[0026] 3. Prepare metal tube arrays filled with aluminum, copper, or silver tubes that have good thermal conductivity and are filled with composite phase change materials;

[0027] (1) Select a metal tube array with good thermal conductivity, which is sealed at one end, has an outer radius of 5-30mm, a wall thickness of 0.45-0.8mm, and a length of 4-10cm;

[0028] (2) Inject the liquid phase change material obtained in step two into the metal tube array of the obtained aluminum, copper or silver tubes;

[0029] 4. Assemble the protective structure units;

[0030] (1) The metal tube array containing the composite phase change material is tightly fixed to the acrylic plate;

[0031] (2) Fix the metal tube array that has been fixed at one end to another acrylic plate;

[0032] (3) Then fix the outer high light transmittance acrylic sheet, glass or polycarbonate flame retardant material to the upper and lower rectangular acrylic sheets.

[0033] The above-mentioned passive open-air building temperature control structure based on composite phase change materials is organically combined with the open-air building to realize its application.

[0034] Specifically, based on the actual needs of the environment where the open-air building is located, phase change materials are matched to prepare CPCM, suitable structural units are designed, and compatible splicing methods are employed.

[0035] Advantages and beneficial effects of the present invention:

[0036] 1. Precise temperature control: Phase change heat absorption / release buffers temperature fluctuations, reducing thermal stress damage to buildings; 2. High concealment: The flexible sheet design does not adhere to the building surface, preserving its appearance; 3. Long-term stability: MWCNT enhances the thermal conductivity and mechanical strength of the material, resulting in a longer service life; 4. Environmentally friendly: The material is non-toxic and recyclable, meeting building conservation ethics requirements; 5. Easy replacement: When the structure experiences performance degradation after several uses, simply remove the old control structure from the outdoor building and replace it with a better-performing temperature control structure without causing any damage to the outdoor building; 6. Low cost and simple and quick preparation method. Attached Figure Description

[0037] Figure 1 This is a side view of the passive open-air building temperature control structure of the present invention;

[0038] Figure 2 The curve showing the relationship between the enthalpy of the filling material and temperature;

[0039] Figure 3 This is an experimental test diagram of the passive open-air building temperature control structure of the present invention;

[0040] Figure 4 This is a schematic diagram of the application of the passive open-air building temperature control structure of the present invention in embodiment 1 (the placement position of the structure is marked in the figure);

[0041] Figure 5 This is a schematic diagram of the application of the passive open-air building temperature control structure of the present invention in embodiment 2 (the placement position of the structure is marked in the figure);

[0042] Figure 6This is a schematic diagram of the application of the passive open-air building temperature control structure of the present invention in embodiment 3 (the placement of the structure is marked in the figure); Detailed Implementation

[0043] The technical solution of the present invention will be further described below through embodiments and in conjunction with the accompanying drawings.

[0044] This invention addresses the problems of high energy consumption, structural complexity, poor compatibility, and high cost associated with traditional open-air building structures in improving the internal thermal environment. It proposes a passive temperature control structure for open-air buildings based on composite phase change materials. This structure comprises three parts: an outer frame structure, filling material, and filling chambers. The outer frame structure is made of a flame-retardant material with high light transmittance. The filling material is a mixture of phase change material, thermal conductivity enhancer, and dispersant. The filling chambers are composed of a metal array with good thermal conductivity. Notably, this invention uses paraffin wax as the primary filling material. Based on the energy storage and release principle of paraffin wax, when the ambient temperature rises to the melting point of the phase change material, the material changes from solid to liquid, absorbing and storing a large amount of heat to prevent further temperature increases. When the ambient temperature drops to the freezing point, the material returns from liquid to solid, releasing the stored heat to slow the temperature drop, thus achieving a dynamic temperature equilibrium. The enthalpy-temperature relationship curve of the filling material is shown below. Figure 2 As shown.

[0045] In some embodiments of the present invention, the outer rectangular frame is made of flame-retardant materials such as high-transmittance acrylic sheet, glass, or polycarbonate. The rectangular structure parameters are: length ranging from 20-30cm, width from 10-20cm, and height from 5-10cm. Specifically, the above parameters are not limited to these ranges and can be adjusted based on them.

[0046] In some embodiments of the present invention, the filler material is a mixture of a phase change material, a thermal conductivity enhancer, and a dispersant. The thermal conductivity enhancer in the filler material is paraffin wax, the thermal conductivity enhancer is multi-walled carbon nanotubes, and the dispersant is oleic acid. The mass concentration of the thermal conductivity enhancer is 0-5 wt%, and the ratio of dispersant to thermal conductivity enhancer is 1:1.7 by mass. As a further embodiment, the mass concentration of the thermal conductivity enhancer multi-walled carbon nanotubes doped in the filler material is 0-5 wt% of the total amount, with the optimal effect corresponding to a mass concentration of 3%.

[0047] In some embodiments of the present invention, the flame-retardant material has a thickness of 5-8 mm. The filling chamber is composed of an array of metals with good thermal conductivity, such as aluminum tubes, silver tubes, and copper tubes. The array unit structure dimensions are: outer radius of 5-30 mm, wall thickness of 0.45-0.8 mm, and length of 4-10 cm. Specifically, the above parameters are not limited to this range and can be adjusted based on the above parameter range.

[0048] Example 1:

[0049] Figure 1 The diagram shows an open-air temperature control structural unit for agricultural greenhouses. This unit includes an outer frame structure 1 made of flame-retardant materials such as high-transmittance acrylic sheets, a filling material 2 composed of a mixture of phase change materials such as paraffin and multi-walled carbon nanotubes, and a filling chamber 3 composed of a metal array such as aluminum tubes with good thermal conductivity. The specific fabrication and operation process of this unit structure are as follows:

[0050] 1. Preparation process

[0051] (1) Fabrication of the outer frame structure

[0052] ① Process high-transmittance flame-retardant materials such as acrylic sheets, glass, and polycarbonate with a thickness of 5mm, a length range of 20cm, and a width of 10cm, as the outer material of the protective structure, for subsequent direct installation on open-air buildings, or installation after splicing multiple units;

[0053] ② Two rectangular acrylic sheets, glass, polycarbonate and other flame-retardant materials with a thickness of 5mm, a length range of 20cm and a width of 10cm are processed for subsequent fixing of the filling chamber, while ensuring the light transmittance of this structure;

[0054] (2) Preparation of filler material

[0055] ①Melting and mixing: Completely melt phase change materials such as paraffin in a constant temperature water bath at 60℃;

[0056] ② Doping and dispersion: Add MWCNT and oleic acid at a mass ratio of 1:1.7, and stir magnetically at a constant temperature for 60 minutes;

[0057] ③ Homogenization treatment: Ultrasonic water bath oscillation for 90 minutes to ensure uniform dispersion of nanoparticles;

[0058] ④ Molding: After cooling, a uniform composite material is obtained.

[0059] (3) Preparation of the filling chamber;

[0060] Prepare an array of thermally conductive metal tubes such as aluminum, silver, and copper, with one end sealed, an outer radius of 5 mm, a wall thickness of 0.45 mm, and a length of 4 cm.

[0061] (4) Assemble the temperature control structural units for open-air buildings;

[0062] ① Inject the filling material prepared in step (2) into the thermally conductive metal tube array in the filling chamber of step (3);

[0063] ②Use the two acrylic plates from step (1) to tightly fix the filling chamber containing the composite phase change material;

[0064] 2. Performance testing of unit structures

[0065] The performance of the fabricated temperature control structural unit was tested. The unit was placed in a high and low temperature alternating chamber to simulate the temperature changes throughout the day on July 22, 2024, in Conghua District, Guangzhou City. The results were obtained after continuous simulation for 48 hours in the high and low temperature alternating chamber. Figure 3 The test curve shown.

[0066] 3. This temperature control unit is integrated with agricultural greenhouse machinery.

[0067] Based on the climate conditions of the agricultural greenhouse and the specific characteristics of the greenhouse, the doping ratio and dispersion process of multi-walled carbon nanotubes (MWCNTs) and phase change materials were optimized to improve their thermal conductivity and thermal cycling stability. The number of structural units and their assembly shape were determined according to the actual shape and size of the agricultural greenhouse to achieve efficient temperature control inside the greenhouse. A schematic diagram of the actual application is shown below. Figure 4 As shown.

[0068] Example 2:

[0069] Unlike Example 1, the outer rectangular frame of this example has a processing thickness of 10mm, a length range of 30cm, and a width of 20cm.

[0070] Example 3:

[0071] Unlike Examples 1 and 2, the outer rectangular frame of this example has a processing thickness of 8mm, a length range of 25cm, and a width of 15cm.

[0072] Example 4:

[0073] Unlike Example 1, the thermal conductivity enhancer concentration in the filler material of this example is 5 wt%.

[0074] Example 5:

[0075] Unlike Examples 1 and 4, the thermal conductivity enhancer concentration in the filler material of this example is 3 wt%.

[0076] Example 6:

[0077] Unlike Example 1, the filling chamber array unit in this example has an outer radius of 30mm, a wall thickness of 0.8mm, and a length of 10cm.

[0078] Example 7:

[0079] Unlike Examples 1 and 6, the filling chamber array unit in this example has an outer radius of 15mm, a wall thickness of 0.6mm, and a length of 7cm.

[0080] The passive open-air building temperature control structure based on composite phase change materials prepared by the above method of the present invention can be used not only in the agricultural greenhouse shown in Example 1, but also in the following examples. However, these are merely examples, and any beneficial extensions can be made to its application based on the present invention, and it can be applied to any related field.

[0081] Application Example 1:

[0082] In this application example, the obtained temperature control unit is organically integrated with open-air cultural relics for the protection of these relics. A schematic diagram of the actual application is shown below. Figure 5 As shown.

[0083] Application Example 2:

[0084] In this application example, the temperature control unit is organically integrated with the residential building for temperature control. A schematic diagram of the actual application is shown below. Figure 6 As shown.

[0085] It should be further noted that the above embodiments are merely for understanding the technical solution of the present invention and are not intended to limit the scope of protection of the present invention. Any obvious adjustments and modifications made to the technical solution of the present invention that fall within the inventive concept should also fall within the scope of protection of the present invention.

Claims

1. A passive open-air building temperature control structure based on composite phase change material, the structure comprising three parts: an outer frame structure, filling material, and filling chamber; the outer frame structure is composed of flame-retardant material with high light transmittance, the filling material is a mixture of phase change material, thermal conductivity enhancer, and dispersant, and the filling chamber is composed of a metal array with good thermal conductivity. The thermal conductivity enhancer in the filler material has a mass concentration of 0-5 wt%, and the ratio of thermal conductivity enhancer to dispersant is 1:1.7 by mass.

2. The passive open-air building temperature control structure based on composite phase change materials according to claim 1, characterized in that: The outer rectangular frame is made of a flame-retardant material selected from high-transmittance acrylic sheet, glass, and polycarbonate. The rectangular structure parameters are: length range of 20-30cm, width of 10-20cm, and height of 5-10cm.

3. The passive open-air building temperature control structure based on composite phase change materials according to claim 2, characterized in that: The thickness of the flame-retardant material is 5-8 mm.

4. The passive open-air building temperature control structure based on composite phase change materials according to claim 1, characterized in that: The filler material is composed of a phase change material paraffin as the main component, multi-walled carbon nanotubes for improving thermal conductivity, and oleic acid as a dispersant, which are uniformly mixed together. The mass concentration of multi-walled carbon nanotubes doped in the filler material is 3%.

5. The passive open-air building temperature control structure based on composite phase change materials according to claim 1, characterized in that: The filling chamber is composed of a metal array of aluminum tubes, silver tubes, and copper tubes with good thermal conductivity. The array unit has the following structural dimensions: outer radius of 5-30mm, wall thickness of 0.45-0.8mm, and length of 4-10cm.

6. The method for preparing a passive open-air building temperature control structure based on composite phase change materials according to any one of claims 1-5, characterized in that... Includes the following steps: I. Selection of Composite Phase Change Materials Matrix material: paraffin; Thermal conductivity enhancer: Multi-walled carbon nanotubes (MWCNTs), with a mass concentration of 0-5 wt%; Dispersant: Oleic acid, added at a ratio of MWCNT:Oleic acid = 1:1.7 by mass; II. Preparation of Phase Change Filler Materials Melting and mixing: The paraffin wax is completely melted in a constant temperature water bath at 60°C; Doping and dispersion: Add MWCNT and oleic acid in proportion, and stir magnetically at a constant temperature for 60 minutes; Homogenization process: Ultrasonic water bath oscillation for 90 minutes to ensure uniform dispersion of nanoparticles; Molding: After cooling, a uniform composite phase change filler material is obtained; III. Fabrication of Passive Outdoor Building Temperature Control Structures (i) Select acrylic sheets, glass or polycarbonate flame-retardant materials with a thickness range of 5-10mm, a length range of 20-30cm, and a width range of 10-20cm as the outer material of the protective structure for subsequent embedding into the original protective structure or multiple splicing. (ii) Select two rectangular acrylic, glass or polycarbonate sheets with a thickness range of 5-10mm, a length range of 20-30cm and a width range of 10-20cm to fix the metal tube array and ensure the light transmittance of this structure. (III) Preparation of metal tube arrays filled with aluminum, copper or silver tubes with good thermal conductivity of composite phase change materials; (1) Select a metal tube array with good thermal conductivity, which is sealed at one end, has an outer radius of 5-30mm, a wall thickness of 0.45-0.8mm, and a length of 4-10cm; (2) Inject the liquid phase change material obtained in step two into the metal tube array of the obtained aluminum, copper or silver tubes; (iv) Assemble the protective structure unit; (1) The metal tube array containing the composite phase change material is tightly fixed to the acrylic plate; (2) Fix the metal tube array that has been fixed at one end to another acrylic plate; (3) Then fix the outer high light transmittance acrylic sheet, glass or polycarbonate flame retardant material to the upper and lower rectangular acrylic sheets.

7. The application of the passive open-air building temperature control structure based on composite phase change materials as described in any one of claims 1-5, characterized in that: Used for open-air construction.

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