A phase change heat storage block and a solar greenhouse

Abstract

The present invention relates to a phase change heat storage block and a solar greenhouse. The phase change heat storage block comprises raw materials in the following mass percentages: 83-92% of fly ash phase change balls, 5-10% of cement by mass, 2-5% of gypsum, and 1-2% of non-ionic surfactant by mass. After adding 18-25% of water based on the total mass of the raw material mixture and stirring and mixing evenly, it is placed in a brick pressing mold and pressed into shape. The phase change block of the present invention has a relatively high thermal conductivity. Through the treatment of fly ash phase change balls and the combination of non-ionic surfactant, the phase change material is well directly applied to the preparation of the block, and it is not easy to leak, and has a relatively high heat storage coefficient.

Description

Technical Field

[0001] The present invention relates to a phase change heat storage block and a solar greenhouse, belonging to the technical fields of phase change energy storage and solar greenhouse technology. Background Art

[0002] Energy is a key factor for the production and development of solar greenhouses. The wall of a solar greenhouse has functions of load-bearing, heat collection, heat storage and heat preservation, and is an important heat supply source for the greenhouse at night in winter. The stronger the ability of the wall to store solar energy during the day, the more heat it can provide to the greenhouse at night. However, since the traditional wall materials of solar greenhouses are usually sensible heat storage materials (such as clay brick walls and soil walls), the utilization of solar energy by the greenhouse wall is limited only by the sensible heat storage method.

[0003] Adopting environmentally friendly wall materials and improving the utilization rate of cultivated land and solar energy have become an urgent need for building modern solar greenhouses and promoting the development of modern facility agriculture. With the continuous progress of phase change heat storage material technology, the passive heat storage and release characteristics of phase change materials can store and release a large amount of phase change latent heat under constant temperature or near-constant temperature conditions. The phase change materials with high heat storage performance can fully absorb and accumulate the solar heat energy irradiated on the surface of the north wall during the day, and then release the accumulated heat at night to maintain and stabilize the temperature in the greenhouse, achieving the effects of improving the utilization rate of solar energy, reducing the consumption of conventional energy, thinning the thickness of the greenhouse wall, and increasing the land utilization rate.

[0004] However, during the use of phase change heat storage materials, there are problems such as supercooling, corrosion and leakage. Factors such as low thermal conductivity, low heat storage speed, and small heat storage density greatly reduce the heat storage performance of composite phase change materials. In order to improve the leakage and corrosion problems of phase change materials during the solid-liquid phase transition process, finding a suitable carrier matrix and treatment method to encapsulate the fluid phase change materials into a shape-stable porous support is one of the key problems in the preparation of composite phase change materials for phase change solar greenhouses.

[0005] For the current phase change material walls, in one way, there is a phase change material layer between the inner wall and the outer wall. After the outer cement wall is formed, it is separated from the phase change material layer and the inner wall, resulting in an air isolation layer, and heat cannot be better introduced into the wall; another way is the full in-situ casting method. Due to the large side pressure generated by formwork support and pouring, it is easy to cause formwork swelling and slurry leakage, which is difficult to repair and time-consuming and laborious; thirdly, the blocks directly made by adding phase change materials have insufficient strength. When reaching the phase temperature, the phase change materials leak seriously, which easily causes collapse and affects the safety and heat storage effect of the solar greenhouse. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a phase change block that meets the strength requirements of the wall of a solar greenhouse during the phase change process, where the phase change material does not leak during the phase change process, has a high heat storage efficiency, and a fast latent heat release rate.

[0007] The technical solution of the present invention to solve the above technical problems is as follows: A phase change heat storage block comprises raw materials in the following mass percentages: 83 - 92% of fly ash phase change balls, 5 - 10% of cement by mass, 2 - 5% of gypsum, and 1 - 2% of non-ionic surfactant by mass. After adding 18 - 25% of water based on the total mass of the raw material mixture and stirring evenly, it is placed in a brick pressing mold and pressed into shape.

[0008] The phase change block of the present invention has a relatively high thermal conductivity. Through the treatment of fly ash phase change balls and the combination of non-ionic surfactants, the phase change material can be directly applied to the preparation of the block well, and it is not easy to leak, having a relatively high heat storage coefficient.

[0009] On the basis of the above technical solution, the present invention can also be improved as follows.

[0010] Further, the particle size of the fly ash phase change balls is 2 - 5 mm.

[0011] Further, the pressure for pressing into shape in the brick pressing mold is 1 - 3 MPa.

[0012] Further, the fly ash phase change balls are prepared through the following steps: Mix fly ash and a cationic surfactant in a mass ratio of 35 - 40:1, add 18 - 25% of water based on their total mixing mass and stir to fully mix and react, and then perform drying and pulverization to obtain activated fly ash; preferably, mix fly ash and a cationic surfactant in a mass ratio of 39:1;

[0013] Heat 25 - 30 parts by mass of an organic eutectic phase change heat storage material to melt above the eutectic phase change temperature, add 35 - 45 parts by mass of the activated fly ash and stir for 30 - 60 min, and then add 20 - 25 parts by mass of a composite gel - shaped inorganic phase change heat storage material to form balls on a ball - forming machine.

[0014] Further, the non-ionic surfactant is selected from one of epoxy - based diacetate POD, ethylenediamine oleate EDO - 865, branched secondary alcohol polyoxyethylene ether (S50), C13 isopropylamine DF - 21 (carbon 13), AG1202 essential oil emulsifier (amino sugar ester), polyether polyol (CF - 60);

[0015] The cationic surfactant is selected from one of dodecyl dimethyl benzyl ammonium chloride, didodecyl dimethyl ammonium chloride, octyldecyl dimethyl ammonium chloride, cetyl trimethyl ammonium bromide, tetradecyl trimethyl ammonium bromide, octadecyl trimethyl ammonium bromide.

[0016] Furthermore, the organic eutectic phase change heat storage material is made of raw materials including the following mass percentages: 90% of the organic eutectic of two organic phase change heat storage materials with phase change temperatures between 30°C and 68°C, 5% - 8% of high-carbon-based materials, and 2% - 5% of nano-thermal conductive materials;

[0017] The composite gel-shaped inorganic phase change heat storage material is made of raw materials including the following mass percentages: 87% - 93% of various gel-shaped phase change materials, 5% - 8% of high-carbon-based materials, and 2% - 5% of nano-thermal conductive materials; the various gel-shaped phase change materials are respectively 85% - 90% of the hot solutions formed by the first inorganic phase change material with a phase change temperature of 8.0°C - 78°C and the second inorganic phase change material with a phase change temperature of 30°C - 78°C, 10% - 15% of a polymer water-absorbing material, and various gel-shaped phase change materials are obtained respectively. The temperature of the hot solution is the phase change temperature of each inorganic phase change material, and the water content is below 15%; the phase change temperatures of the first inorganic phase change material and the second inorganic phase change material are different.

[0018] Furthermore, the mass ratio of the two organic phase change heat storage materials with phase change temperatures between 30°C and 68°C is 1:1 - 2:1; the mass ratio of the first inorganic phase change material to the second inorganic phase change material is 1:1; or it further includes a third inorganic phase change material with a phase change temperature different from that of the first inorganic phase change material and the second inorganic phase change material, and the mass ratio of the first inorganic phase change material, the second inorganic phase change material, and the third inorganic phase change material is 1:1:1.

[0019] Furthermore, the two organic phase change heat storage materials with phase change temperatures between 30°C and 68°C are lauric acid and myristic acid; n-tricosane and n-heptacosane; PEG2000 and PEG10000; n-tetradecanoic acid and n-octadecanoic acid; n-tricosane and n-octacosane; n-heneicosane and n-octacosane; n-heneicosane and n-hexacosane; dodecanoic acid and myristic acid; PEG1000 and PEG4000;

[0020] The first inorganic phase change material and the second inorganic phase change material are: lithium nitrate trihydrate and calcium chloride hexahydrate; dipotassium hydrogen phosphate hexahydrate and sodium carbonate decahydrate; zinc chloride trihydrate and sodium sulfate decahydrate; sodium chromate decahydrate and disodium hydrogen phosphate dodecahydrate or potassium fluoride tetrahydrate and zinc nitrate hexahydrate;

[0021] The first inorganic phase change material, the second inorganic phase change material and the third inorganic phase change material are zinc chloride trihydrate, magnesium sulfate heptahydrate and sodium sulfate decahydrate; dipotassium hydrogen phosphate hexahydrate, disodium hydrogen phosphate dodecahydrate and disodium hydrogen phosphate heptahydrate; sodium chromate water, sodium carbonate decahydrate and sodium thiosulfate pentahydrate; manganese nitrate hexahydrate, calcium bromide hexahydrate and zinc nitrate tetrahydrate or three sodium hydroxide hemihydrates, sodium carbonate decahydrate and sodium hydroxide monohydrate.

[0022] Further, the high carbon-based material is one or more of graphite, graphene, carbon nanotubes, porous carbon, activated carbon or carbon black;

[0023] The nano thermal conductive material is one or more of nano metal silver, nano metal copper, nano metal gold, nano metal aluminum, nano metal tungsten, and nano metal zinc;

[0024] The high molecular polymer water-absorbing material is one or more of polyethylene glycol (PEG), polyethylene oxide (PEO), polyacrylamide (PAM), potassium polyacrylate (PAA-K), sodium polyacrylate (PAA-Na), polyacrylic acid (PAA), and polyvinyl alcohol (PVA).

[0025] Further, the preparation of the organic eutectic is as follows: two organic phase change thermal storage materials with different phase change temperatures are introduced into a water bath heated magnetic stirrer, and heated in a water bath at 50°C-80°C in a sealed state until all components are completely melted, and the heating and stirring are continued for 20-50 minutes, and dried in a constant temperature drying oven at 60-85 for 5-12 hours, and a white block solid is obtained after cooling, and the organic eutectic is obtained by ultrafine grinding;

[0026] Preparation of the organic eutectic phase change thermal storage material: introducing a high carbon-based material and a nano thermal conductive material into the organic eutectic under stirring, adjusting the heating temperature until the organic eutectic phase change material melts, stirring for 20-50 minutes, naturally cooling in a closed dry environment at 15-25° C., and crushing after solidification to obtain a high carbon-based high thermal conductive organic eutectic phase change thermal storage material;

[0027] Preparation of the composite gel-shaped inorganic phase change thermal storage material:

[0028] 1) dissolving the first inorganic phase change material and the second inorganic phase change material, or the first inorganic phase change material, the second inorganic phase change material and the third inorganic phase change material in an appropriate amount of distilled water, respectively, stirring with a magnetic force, heating the corresponding phase change material solutions in a water bath at 50° C.-90° C., stirring the solutions until the solids are completely dissolved and the solutions become transparent, and filtering the solutions to remove any solid impurities;

[0029] 2) Transfer the filtered solution to a dry sealable container, seal it and place it in a thermostatic bath to control the temperature of the solution. Slowly lower the temperature of the solution until it reaches the phase change temperature of the corresponding phase change heat storage material respectively. Concentrate each solution to a water content of less than 15%, cool it to room temperature to obtain a variety of the above-mentioned hot solutions. Slowly add a polymer absorbent material to the inorganic phase change heat storage solution respectively, and fully stir to form a variety of the above-mentioned gel-type shaped phase change materials;

[0030] 3) Mix a variety of the above-mentioned gel-type shaped phase change materials, add a high-carbon-based material and a nano-thermal conductive material, stir for half an hour, then put the mixture into a thermostatic drying oven for drying, and naturally cool it in a sealed drying environment at 20°C until it solidifies and then crush it to obtain the finished product.

[0031] The present invention also provides a solar greenhouse, including a greenhouse wall, and the above-mentioned phase change heat storage blocks are used to build the greenhouse wall.

[0032] Furthermore, the thickness of the greenhouse wall is 400 - 600 mm, a nano-thermal conductive coating with a thickness of 200 - 800 μm is painted on the inner side of the greenhouse wall, and an extruded polystyrene insulation board with a thickness of 90 - 150 mm is provided on the outer wall of the greenhouse wall.

[0033] The beneficial effects of the present invention are as follows:

[0034] 1. During the activation process of fly ash in the present invention, the addition of a cationic surfactant improves the activity of fly ash, promotes its interaction with the pore phase change material and other components in fly ash, thereby achieving the purpose of forming an inorganic seal at the end of the pore phase change material; based on the problem that the organic phase change material is prone to leakage, the addition of a cationic surfactant in the present invention will form a thin film on the surface of fly ash, change its surface properties, increase its interaction with water and other materials, can reduce the adsorption force between fly ash particles, promote its dispersion, and is beneficial to better mixing and reaction with the organic phase change material to form a uniform reaction system; at the same time, it can reduce the interfacial tension between fly ash and the surrounding medium, making fly ash more likely to interact with other organic phase change materials, which is beneficial to the combination between the pore organic phase change material and fly ash; in addition, adding a specific type of cationic surfactant can promote the formation and growth of crystal nuclei of the pore organic eutectic phase change material, thereby forming a more dense and stable inorganic seal structure at the end; more importantly, it can improve the reaction activity during the activation process of fly ash, accelerate the formation and sealing process of the pore organic phase change material, and thus improve the sealing effect.

[0035] 2. When the humidity and temperature in the fly ash balls change, the pore phase change material will release or absorb moisture and form an inorganic sealing substance at the pore openings. The formation of this inorganic sealing substance is due to the interaction between the pore phase change material, the surfactant, and other components in the fly ash, resulting in the deposition, crystallization, or reaction of substances near the pore openings. The surfactant promotes the formation of the inorganic sealing substance by increasing the interaction between the fly ash, the pore phase change material, and other components in the fly ash. It can increase the interaction between the fly ash and water, making it easier to react with the pore phase change material, thus promoting the generation and fixation of the inorganic sealing substance.

[0036] 3. Since the inorganic sealing substance is formed inside the fly ash and interacts with the components in the fly ash, it has good stability and durability, and can effectively prevent the penetration of the phase change material for a long time, thus protecting the durability and performance of the fly ash composite phase change heat storage material structure.

[0037] 4. Based on the fact that the surfaces of most polymer absorbent materials are anionic or non-ionic, on the surface of the fly ash phase change heat storage material added with a cationic surfactant, cationic modification can change the surface properties of the fly ash and increase the interaction between it and the negatively charged polymer absorbent materials (sodium polyacrylate and potassium polyacrylate). Through cationic modification, positively charged groups can be introduced to increase the charge interaction between the fly ash and the polymer gel surface, thereby enhancing the adsorption effect of the two phase change materials. The polymers are in a gel state in water and have strong adsorption properties. When they come into contact with cation-modified fly ash, charge neutralization and chemical adsorption occur, resulting in the binding of the polymer to the fly ash surface. The main manifestations are as follows:

[0038] Increased adsorption amount: The positive charge of the cation-modified fly ash enhances the attraction between the fly ash and the polymer gel, resulting in more polymer molecules being adsorbed onto the fly ash surface.

[0039] Change in adsorption rate: The change in the surface properties of the cation-modified fly ash affects the adsorption kinetics, resulting in a change in the adsorption rate. It is manifested as a faster or slower adsorption rate.

[0040] Change in adsorption selectivity: The characteristics of the cation-modified fly ash lead to different adsorption selectivities for polymer gels. Stronger adsorption of anionic and non-ionic polymers.

[0041] Change in adsorption equilibrium: The addition of cation-modified fly ash changes the adsorption equilibrium conditions, including the adsorption isotherm and the equilibrium adsorption amount. This is very beneficial to the operation of the building blocks added with phase change heat storage.

[0042] Changes in the properties of the polymer after adsorption: The polymer adsorbed on the surface of cation-modified fly ash will undergo conformational changes or cross-linking, causing cross-linking reactions between the organic eutectic phase change material encapsulated by fly ash and the inorganic phase change material encapsulated by the polymer, achieving the "anchoring" of inorganic-organic phase change materials. The conformational change of the polymer adsorbed on the surface of cation-modified fly ash will form a polymer-fly ash interpenetrating network structure, thus solving the durability and performance of the structure of organic-inorganic phase change composite materials, and further solving the supercooling of inorganic phase change materials and the leakage problem of phase change materials.

[0043] 5. The organic-inorganic composite phase change material formed by a ball-making machine is used as a core material and added to the high-carbon-based high-thermal-conductivity composite phase change energy storage block (prefabricated panel) system. By selecting a non-ionic surfactant, the cement-based inorganic material is wrapped on the surface of the core material ball to further encapsulate and wrap the organic-inorganic composite phase change material. By adding a non-ionic surfactant to the cement-based material, the stability, durability, and various properties of the high-carbon-based high-thermal-conductivity composite phase change energy storage block (prefabricated panel) structure are further enhanced through the charge interaction, electrostatic attraction, and chemical adsorption with the phase change ball of the organic-inorganic composite phase change material. The main aspects are as follows:

[0044] Charge interaction: The non-ionic modified cement-based material adsorbs the ions on the surface of the phase change ball of the organic-inorganic composite phase change material through electrostatic interaction. The non-ionic modification of the cement-based mixed material causes changes in its surface chemical properties, making it more affinity and binding more tightly with the charged polymer on the surface of the phase change ball of the organic-inorganic composite phase change material.

[0045] Improved adsorption capacity: The non-ionic modified cement-based material enhances its adsorption capacity for the charged polymer on the surface of the phase change ball of the organic-inorganic composite phase change material through its surface characteristics. There may be an electrostatic attraction between it and the non-ionic modified cement-based material, which helps to increase the adsorption efficiency and amount.

[0046] Influence on adsorption kinetics and equilibrium: The modified cement-based material may affect the kinetics of the adsorption process, including the adsorption rate and the time required to reach adsorption equilibrium. This may be due to the larger surface area or more excellent adsorption sites of the modified cement-based material.

[0047] Chemical adsorption: The surface of the non-ionic modified cement-based material may have chemically active functional groups such as hydroxyl (-OH), amino (-NH2), etc. These functional groups can form chemical bonds with the functional groups on the surface of the phase change ball of the organic-inorganic composite phase change material, thus achieving adsorption.

[0048] In the present invention, appropriate amounts of different surfactants are added to adapt to different reaction points, which can effectively improve the compatibility between the phase change ball of the organic-inorganic composite phase change material and cement and the mechanical properties of the cement matrix:

[0049] Enhance the dispersion of phase change spheres of organic-inorganic composite phase change materials: Surfactants can enhance the dispersion of phase change spheres of organic-inorganic composite phase change materials, making them more evenly distributed in the cement matrix. This helps prevent the agglomeration of phase change spheres of organic-inorganic composite phase change materials and improves the compactness and strength of the cement stone.

[0050] Accelerate cement setting: Surfactants can promote the setting and hydration reactions of cement, thereby increasing the strength of the cement matrix. This effect helps form more hydration products in the cement matrix and enhances the mechanical properties of the cement matrix.

[0051] Improve the interfacial bonding between cement and phase change spheres of organic-inorganic composite phase change materials: Surfactants can improve the interfacial bonding between cement-based materials and phase change spheres of organic-inorganic composite phase change materials, enhance the interaction between them, and thus increase the overall strength of the cement matrix.

[0052] Regulate the microstructure of cement stone: The addition of surfactants may change the microstructure of cement stone, such as reducing porosity and increasing the connectivity of pore structures, which all contribute to improving the strength of the cement matrix.

[0053] 6. The present invention uses fly ash phase change spheres, organic eutectic phase change heat storage materials, and non-ionic surfactants in combination to solve the problems of phase change supercooling, leakage, and cycle times of inorganic phase change heat storage materials.

[0054] 7. A gel-type shaped phase change material is made of a high molecular polymer water-absorbing material and an inorganic phase change material, enabling the gel-type shaped phase change material to form a gel state after absorbing water, maintaining the shape stability of the phase change material. It can retain the absorbed water inside and is not easily lost, which allows the gel-type shaped phase change material to retain water for a long time, delay the evaporation of water, and increase the service life of the phase change material; the inorganic shaped phase change material has good long-term stability and can withstand multiple phase change cycles without being easily degraded or damaged.

[0055] 8. The preparation of gel-type fixed phase change materials using high molecular polymer water-absorbing materials can be used together with materials such as silicate, fly ash / unburned coal gangue to prepare high-performance blocks (precast panels) and improve the strength, durability and impermeability of the blocks (precast panels). It can be added to the cementitious materials of blocks (precast panels) as a binder to enhance the cohesive force and adhesion of the cementitious materials of blocks (precast panels) and improve the crack resistance and impermeability of the blocks (precast panels). It can be added to blocks (precast panels) as a waterproofing agent to fill the micropores and capillaries inside the blocks (precast panels) to form a dense waterproof layer and improve the waterproof performance of the blocks (precast panels). It can be added to blocks (precast panels) as an anti-cracking agent to improve the crack resistance of the blocks (precast panels) and reduce the shrinkage and cracking of the blocks (precast panels).

[0056] 9. The phase change temperature of the present invention is suitable for the needs of different crops grown in the greenhouse. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a schematic diagram of the structure of the solar greenhouse of the present invention.

[0058] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0059] 1. Nano thermal conductive coating layer, 2. Phase change heat storage material layer, 3. Phase change foamed concrete prefabricated block / board wall, 4. Extruded board exterior wall insulation layer, 5. Exterior wall coating layer, 6. Greenhouse rear wall foundation, 7. Underground rear extruded insulation board, 8. Greenhouse rear roof, 9. Quilt, 10. Winch, 11. Greenhouse front roof, 12. Greenhouse front opening foundation, 13. Bottom front extruded insulation board. DETAILED DESCRIPTION

[0060] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0061] 1. Organic phase change thermal storage material: introduce two organic phase change thermal storage materials with different phase change temperatures of 30℃-68℃ into a magnetic stirrer with water bath heating at a mass ratio of 1:1-2:1, heat in a water bath at 50℃-80℃ in a closed state until all components are completely melted, continue heating and stirring for 30 minutes, dry in a 75℃ constant temperature drying oven for 8 hours, and obtain a white block solid after cooling, and then use a grinder to ultra-fine to obtain a finished organic eutectic product. According to 90% of the organic eutectic, stir and introduce and add 5%-8% of high carbon-based (carbon material) and 2%-5% of nano-thermal conductive material. Adjust the heating temperature until the organic eutectic phase change material melts, stir for half an hour, and naturally cool in a closed dry environment at 20℃ until solidified and crushed to obtain a finished high-carbon-based and high-thermal-conductivity organic phase change thermal storage material;

[0062] The raw material components and dosages of Examples A-1 to A-10 of the organic phase change heat storage material are shown in Table 1, and the specific performance indicators are shown in Table 1-1.

[0063] Table 1. Preparation Parameters of Organic Phase Change Heat Storage Material

[0064]

[0065]

[0066] Table 1-1. Performance Indicators of Organic Phase Change Heat Storage Material

[0067]

[0068] II. Composite Gel-shaped Inorganic Phase Change Heat Storage Material: Select inorganic phase change materials with phase change temperatures of 8.0°C - 78°C and inorganic phase change materials with phase change temperatures of 30°C - 78°C. Dissolve two or three inorganic phase change heat storage materials in appropriate amounts of distilled water according to a mass ratio of 1:1 or 1:1:1 respectively, and stir using a magnetic stirrer. Heat the two solutions in a water bath between 50°C - 90°C respectively, and stir the solutions until all the solids are completely dissolved and the solutions become transparent. Filter the solutions respectively to remove any solid impurities. Transfer the filtered solutions to a dry container, seal the container, and place it in a constant temperature bath to control the temperature of the solutions. Slowly lower the temperature of the solutions until they reach the phase change temperatures of the two phase change heat storage materials respectively (at the phase change temperature, the solutions will release a large amount of heat due to the heat storage effect during the phase change process). Concentrate the two / three solutions to 10% water content respectively, cool to room temperature, and obtain two / three inorganic phase change heat storage solutions. Slowly add 10% - 15% of a high molecular polymer water-absorbing material to 85% - 90% of the inorganic phase change heat storage solution by mass respectively, and stir well to form two / three gel-shaped shaped phase change materials. Mix the two / three gel-shaped shaped phase change materials according to a mass ratio of 1:1 or 1:1:1, add 5% - 8% of a high carbon-based material and 2% - 5% of a nano-thermal conductivity material, stir for half an hour, then place the mixture in a constant temperature drying oven to dry, and naturally cool in a closed drying environment at 20°C until it solidifies and then crush to obtain the composite gel-shaped inorganic phase change heat storage material.

[0069] For Examples B-1 to B-10 of the composite gel-shaped inorganic phase change heat storage material, the raw material components and dosages are shown in Table 2, and their performance indicators are shown in Table 2-1.

[0070] Table 2. Preparation Parameters of Composite Gel-shaped Inorganic Phase Change Heat Storage Material

[0071]

[0072]

[0073] Table 2-1. Performance Indexes of Composite Gel Fixed Inorganic Phase Change Heat Storage Materials

[0074]

[0075] According to the performance indexes of the organic phase change heat storage materials shown in Table 1-1, the organic composite has a relatively high eutectic phase change point temperature. For the performance indexes of the composite gel fixed inorganic phase change heat storage materials in Table 2-1, the phase change latent heat is high. The present invention can achieve three to four phase change temperature points suitable for crop growth requirements and the phase change latent heat to meet the growth requirements of different crops.

[0076] III. Fly Ash Phase Change Balls:

[0077] Examples C-1 to C-15 of fly ash phase change balls: Mix fly ash and a cationic surfactant in a mass ratio of 35-40:1, add 18-25% of the total mass of the mixture of water and stir to fully mix and react, then dry and pulverize to obtain activated fly ash with an average particle size of 2-5 mm; the cationic surfactant is selected from one of dodecyl dimethyl benzyl ammonium chloride, bisdecyl dimethyl ammonium chloride, octyldecyl dimethyl ammonium chloride, cetyl trimethyl ammonium bromide, tetradecyl trimethyl ammonium bromide, and octadecyl trimethyl ammonium bromide;

[0078] Heat 25-30 parts by mass of the organic eutectic phase change heat storage material to melt above the eutectic phase change temperature, add 35-45 parts by mass of the activated fly ash and stir well for 30-60 min, then add 20-25 parts by mass of the composite gel fixed inorganic phase change heat storage material and form balls on a ball forming machine.

[0079] CK-1 is set as fly ash without being treated with a cationic surfactant, directly mixed with the organic eutectic phase change heat storage material and the composite gel fixed inorganic phase change heat storage material after heating to melt above the eutectic phase change temperature, and form balls on a ball forming machine.

[0080] The raw material components and dosages of Examples C-1 to C-15 of fly ash phase change balls and the control group CK-1 are shown in Table 3.

[0081] Table 3. Preparation Parameters of Fly Ash Phase Change Balls

[0082]

[0083] IV. Fly Ash Phase Change Blocks:

[0084] Examples D1 to D13 for preparing fly ash phase change blocks: 83 - 92% of fly ash phase change balls, the fly ash phase change balls preferably have an average particle size of 2 - 5 mm, 5 - 10 parts by mass of cement, 2 - 5% of gypsum, and 1 - 2 parts by mass of non-ionic surfactant. After the mixture of the raw materials is added with water and stirred evenly at a mass-volume ratio of 1:0.1 - 0.15, it is formed by a mold. The size of the block is 100 cm * 50 cm * 50 cm, preferably placed in a brick pressing mold and pressed into shape under a pressure of 1 - 3 MPa, more preferably 2 - 2.8 MPa, and most preferably a pressure of 2.5 MPa; the non-ionic surfactant is selected from one of epoxy diacetate POD, ethylenediamine oleate EDO-865, branched secondary alcohol polyoxyethylene ether (S50), C13 isopropyl alcohol amide DF-21 (carbon 13), AG1202 essential oil emulsifier (amino sugar ester), polyether polyol (CF-60).

[0085] In this example, the control groups are set as CK-01, CK-02, CK-03, CK-04, CK-05, CK-06, and CK-07. CK-01 is that no non-ionic surfactant is added during the block preparation process; CK-02 is that the fly ash is not treated with a cationic surfactant and no non-ionic surfactant is added during the block preparation process; CK-03 is that the fly ash is not treated with a cationic surfactant and a non-ionic surfactant is added during the block preparation process; CK-04 is that the fly ash is not treated with a cationic surfactant and no anionic surfactant (sodium lauryl sulfate) is added during the block preparation process; CK-05 is that an anionic surfactant (fluorooctyl carboxylate) is added during the block preparation process; CK-06 is that fly ash not treated with a cationic surfactant is directly mixed with a phase change material to prepare a block (not formed into phase change balls); CK-07 is a fly ash block directly made from fly ash not treated with a cationic surfactant.

[0086] The raw material components and dosages of fly ash phase change blocks in Examples D1 - D14 and each control group CK-01, CK-02, CK-03, CK-04, CK-05, CK-06, and CK-07 are shown in Table 4, and the specific performance parameters of the blocks are shown in Tables 4-1 and 4-2.

[0087] The leakage rate of the phase change block is tested by the mass loss method:

[0088] 1. Preparation of block samples: Prepare the phase change material samples to be tested and ensure that they meet the experimental requirements, including preparation work in aspects such as size, mass, and state.

[0089] 2. Weighing: Use an accurate balance to weigh the initial mass of the phase change material sample and record it as the reference value.

[0090] 3. Exposure: Place the phase change material sample in a temperature-changing test chamber with a set temperature change range of -40 - 60°C and test under normal pressure.

[0091] 4. Time monitoring: During the test, monitor the mass change of the phase change material sample every month; weigh the sample and record the mass.

[0092] 5. Calculate the loss rate: Calculate the mass loss rate of the phase change block sample based on the monitored mass change data by comparing the difference between the initial mass and the final mass;

[0093] 6. Analyze the loss rate data after 6 months of testing to evaluate the performance and leakage situation of the phase change block sample, calculate the leakage rate, (Initial mass - Final mass / Initial mass) * 100%.

[0094] Table 4. Preparation parameters of fly ash phase change blocks and control examples

[0095]

[0096]

[0097] Table 4 - 1. Performance indicators of phase change heat storage blocks and control group tests - I

[0098]

[0099]

[0100] Table 4 - 2. Performance indicators of phase change heat storage blocks and comparative tests - II

[0101] Block Strength after 7-day conventional curing / mpa Leakage rate of phase change material % D-1 3.5 2.6 D-2 3.4 2.7 D-3 3.5 2.2 D-4 3.6 2.9 D-5 4.0 2.6 D-6 3.6 1.8 D-7 6.4 1.5 D-8 7.5 1.0 D-9 3.2 1.6 D-10 5.7 4.8 D-11 3.8 1.9 D-12 3.2 3.6 D-13 2.8 5.2 CK-0 2.7 4.6 CK-01 3.0 5.8 CK-02 3.5 12.5 CK-03 3.4 8.7 CK-04 2.4 9.4 CK-05 2.5 6.7 CK-06 3.0 15.8 CK-07 2.7 None

[0102] According to the method of apparent heat capacity, the concept of equivalent specific heat is deduced, that is, the latent heat of the phase change material is regarded as having a large apparent heat capacity within its phase change temperature range, and this phase change latent heat is converted into the equivalent specific heat of the material within the phase change temperature range. It can be seen from Table 4 - 1 that the equivalent specific heat of the composite phase change energy storage block is about 25 times that of red brick and about 11.5 times that of fly ash block. For example, for D - 1, the specific heat capacity is 25.45 kj / kg·K, and for brick it is 1.05, so 25.45 / 1.05 ≈ 25 times. Thus, from the thermophysical performance parameters of the materials, it also shows that the heat storage performance of the phase change energy storage block of the present invention is significantly superior to that of ordinary red brick wall materials or fly ash wall materials. Due to the addition of the fly ash phase change balls of the present invention, the bulk density of the block is reduced relative to red brick and fly ash block, achieving the purpose of light weight.

[0103] According to the heat transfer process of building envelopes (walls), the thermal properties of building envelopes are usually evaluated by indicators such as thermal resistance R, heat storage coefficient S, and thermal inertia index D. Among them, the thermal resistance R represents the total impedance encountered when heat transfers from one side space of the wall material layer to the other side space. The larger the R value, the better the heat insulation (heat isolation) performance of the wall material layer; the heat storage coefficient S characterizes the sensitivity of the wall material layer to the action of heat flow fluctuations and reflects the resistance ability of the wall material layer to temperature fluctuations. Under the same conditions of heat flow wave action, the larger this value, the smaller the fluctuation of the surface temperature wave of the wall material layer and the better the thermal stability; the thermal inertia index D is a main indicator representing the attenuation degree of the temperature wave on the back wave surface. The larger this value, the stronger the ability of the material layer to resist periodic temperature fluctuations and the ability to store heat.

[0104] As shown in Table 4-1, the performance indicators I of the phase change heat storage blocks and the control group experiments and Table 4-2, the performance indicators II of the phase change heat storage blocks and the control group experiments, the block bulk density of the phase change heat storage blocks D-1 to D-6 in the embodiments of the present invention is suitable, the thermal conductivity is low, and the heat storage coefficient, specific heat capacity, thermal resistance, and thermal inertia index are all relatively high; it has good heat storage performance; at the same time, compared with the comparative examples CK-01 to -05, the addition of different types of surfactants at specific stages in the embodiments of the present invention significantly affects the phase change material leakage rate % of the blocks; no surfactant is added or different types of surfactants are added during the preparation process of the fly ash phase change balls and the preparation process of the blocks, which both result in a significant increase in the leakage rate of the blocks.

[0105] As shown in the embodiments D-7 to D-10, appropriate pressure during the block forming process can enhance the compactness and durability of the blocks, but excessive pressure will cause changes in the material properties of the blocks, and the blocks will deform or break. A large number of experiments show that applying pressure within an appropriate range in the embodiments of the present invention can significantly improve the compressive strength of lightweight blocks, but if the pressure is too large, especially greater than 3 MPa, it will damage the material and cause a significant increase in the phase change material leakage rate.

[0106] As shown in the embodiments D-11 to D-13, if the particle size of the fly ash phase change balls is too small, the heat storage coefficient is relatively low, and the block strength is high. If the particle size is too large, it will cause a significant increase in the leakage rate.

[0107] The design shape parameters or functional parameters of the solar greenhouse of the present invention establish mathematical models and mathematical equations based on the thermal inertia index (D value); establish mathematical models and mathematical equations based on semi-infinite unsteady heat conduction; establish mathematical models and mathematical equations based on solar energy, according to the present invention. This solar greenhouse has excellent heat preservation performance and good heat storage effect, and can achieve all-year-round production in all regions with warm winters and cool summers. The mathematical model equation is established for the building orientation and latitude of the phase change energy storage solar greenhouse, and the optimal orientation γ of the solar energy phase change heat storage type solar greenhouse max can be calculated according to formula (1).

[0108] γ max = 0.01801φ 3 - 2.127φ 2 + 84.16φ - 1109.5………………(1)

[0109] In the formula: φ——local geographical latitude, °N (obtained according to Appendix A).

[0110] Recommended values of the optimal building orientation (azimuth angle) of solar greenhouses in some areas; establishing a mathematical model equation for the potential span ratio, average temperature and average solar radiation of a solar greenhouse with phase change energy storage

[0111] Recommended values of the characteristic parameters of the building space form of a solar greenhouse with span solar energy and phase change heat storage can be seen in the table

[0112] In the formula:

[0113] ——outdoor daily average temperature (°C) during the local overwintering growth period (obtained according to Appendix A);

[0114] ——daily average solar radiation (MJ / (m2·day)) during the local overwintering growth period (obtained according to Appendix A).

[0115] According to an embodiment of the present invention, the main technical parameters of a solar greenhouse (in Chifeng area, Inner Mongolia): front roof angle (α) = 31°; rear roof angle (β) = 47°; span (L) = 10 m; rear roof length (M) = 1.72 m; horizontal projection length of the rear roof L2 = 1.17 m; ridge height of the greenhouse (H) = 5.2 m; height of the rear wall (h) = 3.6 m; greenhouse azimuth angle: 6° west of south; greenhouse spacing N = 5.5 m; greenhouse length = 100 m;

[0116] Rear wall and gable wall: The wall height is 3.6 m, and the outer wall thickness is 600 mm. The solar greenhouse built with phase change energy storage blocks D-1, D-2, D-3, D-4, D-5, D-6, G-7, D-8 and D-9 has an extruded polystyrene insulation board with a thickness of 150 mm on the outer wall; the inner wall surface is painted with a nano-thermal conductive coating with a thermal conductive layer of 800 um; Rear roof: length 1.17 m, thickness 0.15 m, 15 cm extruded polystyrene insulation board; Foundation: depth 1.7 m, thickness 0.7 m, concrete bored pile foundation, and a cold-proof wall with an extruded polystyrene insulation board with a thickness of 150 mm on the outer wall of the foundation.

[0117] The control example CK is a red brick outer wall, with an extruded polystyrene insulation board with a thickness of 150 mm on the red brick outer wall; the inner wall surface is painted with a nano-thermal conductive coating, and the thermal conductive layer is 800 um; the rear roof: with a length of 1.17 m and a thickness of 0.15 m, an extruded polystyrene insulation board with a thickness of 15 cm; the foundation: with a depth of 1.7 m and a thickness of 0.7 m, a concrete bored pile foundation, and a cold-proof wall made of an extruded polystyrene insulation board with a thickness of 150 mm on the outer wall of the foundation.

[0118] Table 5. Performance indicators of a solar greenhouse with high-carbon-based and high-thermal-conductivity composite phase change energy storage blocks (prefabricated panels)

[0119]

[0120]

[0121] Table 6. Performance indicators of plants grown in a solar greenhouse

[0122]

[0123] Note: The data comparison is from December 2020 to February 2021, and the data of Examples D-1 to D-8 are from December 2022 to March 2023.

[0124] According to Table 5 and Table 6 above, for the solar greenhouse according to the embodiments of the present invention, the average temperature difference at night in the greenhouse can be as small as ℃, and the plant height, root length, stem thickness, number of leaves per plant, number of inflorescences per plant, total mass, and total dry mass are all significantly improved.

[0125] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A phase change thermal storage block, characterized in that: The raw materials include the following mass percentages: 83-92% fly ash phase change balls, 5-10% cement, 2-5% gypsum and 1-2% non-ionic surfactant, 18-25% water of the total mass of the raw material mixture is added, stirred and mixed evenly, and then placed in a brick pressing mold for pressing and forming; The fly ash phase change ball is prepared by the following steps: mixing fly ash and cationic surfactant at a mass ratio of 35-40:1, adding 18-25% of the total mass of water, stirring and mixing to react, and drying and crushing to obtain activated fly ash; Heat 25-30 parts by weight of organic eutectic phase change thermal storage material to above the eutectic phase change temperature to melt, add 35-45 parts by weight of the activated fly ash and stir for 30-60 minutes, then add 20-25 parts by weight of composite gel-shaped inorganic phase change thermal storage material and form balls on a ball forming machine; The cationic surfactant is selected from one of dodecyl dimethyl benzyl ammonium chloride, bis dimethyl ammonium chloride, octyl dimethyl ammonium chloride, hexadecyl trimethyl ammonium bromide, tetradecyl trimethyl ammonium bromide and octadecyl trimethyl ammonium bromide; The composite gel-shaped inorganic phase-change thermal storage material comprises the following raw materials in percentage by mass: A plurality of gel-type shaping phase change materials 87%-93%, high carbon-based materials 5%-8% and nano thermal conductive materials 2%-5%; the plurality of gel-type shaping phase change materials are respectively a first inorganic phase change material with a phase change temperature of 8.0°C-78°C and a second inorganic phase change material with a phase change temperature of 30°C-78°C, respectively formed by a hot solution of 85%-90%, and a high molecular polymer water-absorbing material 10%-15%, to obtain the plurality of gel-type shaping phase change materials; The high carbon-based material is one or more of graphite, graphene, carbon nanotubes, porous carbon, activated carbon or carbon black.

2. The phase change thermal storage block according to claim 1, characterized in that: The particle size of the fly ash phase change balls is 2-5 mm.

3. The phase change thermal storage block according to claim 2, characterized in that: The pressure of the brick pressing mold is 1-2.8MPa.

4. The phase change thermal storage block according to claim 1, characterized in that: The nonionic surfactant is selected from one of epoxy diacetate POD, ethylenediamine oleate EDO-865, branched secondary alcohol polyoxyethylene ether, C13 isolactone bisaccharide DF-21, AG1202 essential oil emulsifier, and polyether polyol.

5. The phase change thermal storage block according to claim 1, characterized in that: The organic eutectic phase change thermal storage material comprises the following raw materials in percentage by mass: 90% of organic eutectic of two organic phase change thermal storage materials with different phase change temperatures between 30°C and 68°C, 5%-8% of high carbon-based materials and 2%-5% of nano thermal conductive materials; The temperature of the hot solution is the phase change temperature of each inorganic phase change material, and the water content is less than 15%; the first inorganic phase change material and the second inorganic phase change material have different phase change temperatures; The high carbon-based material is one or more of graphite, graphene, carbon nanotubes, porous carbon, activated carbon or carbon black.

6. The phase change thermal storage block according to claim 5, characterized in that: The mass ratio of the two organic phase change thermal storage materials with different phase change temperatures between 30°C and 68°C is 1:1-2:1; the mass ratio of the first inorganic phase change material to the second inorganic phase change material is 1:1; or it also includes a third inorganic phase change material with a different phase change temperature from the first inorganic phase change material and the second inorganic phase change material, and the mass ratio of the first inorganic phase change material, the second inorganic phase change material and the third inorganic phase change material is 1:1:

1.

7. A phase change thermal storage block according to claim 6, characterized in that: The two organic phase change thermal storage materials with different phase change temperatures between 30°C and 68°C are lauric acid and myristic acid; n-tricosane and n-heptacosane; PEG2000 and PEG10000; n-tetradecanoic acid and n-octacosane; n-tricosane and n-octacosane; n-heonicosane and n-octacosane; n-heonicosane and n-hexacosane; n-dodecanoic acid and n-tetradecanoic acid or PEG1000 and PEG4000; The first inorganic phase change material and the second inorganic phase change material are: lithium nitrate trihydrate and calcium chloride hexahydrate; dipotassium hydrogen phosphate hexahydrate and sodium carbonate decahydrate; zinc chloride trihydrate and sodium sulfate decahydrate; sodium chromate decahydrate and disodium hydrogen phosphate dodecahydrate or potassium fluoride tetrahydrate and zinc nitrate hexahydrate; The first inorganic phase change material, the second inorganic phase change material and the third inorganic phase change material are zinc chloride trihydrate, magnesium sulfate heptahydrate and sodium sulfate decahydrate; dipotassium hydrogen phosphate hexahydrate, disodium hydrogen phosphate dodecahydrate and disodium hydrogen phosphate heptahydrate; sodium chromate water, sodium carbonate decahydrate and sodium thiosulfate pentahydrate; manganese nitrate hexahydrate, calcium bromide hexahydrate and zinc nitrate tetrahydrate or three sodium hydroxide hemihydrates, sodium carbonate decahydrate and sodium hydroxide monohydrate.

8. The phase change thermal storage block according to claim 5, characterized in that: The nano thermal conductive material is one or more of nano metal silver, nano metal copper, nano metal gold, nano metal aluminum, nano metal tungsten, and nano metal zinc; The high molecular polymer water-absorbing material is one or more of polyethylene glycol, polyethylene oxide, polyacrylamide, potassium polyacrylate, sodium polyacrylate, polyacrylic acid, and polyvinyl alcohol.

9. A phase change thermal storage block according to claim 6 or 7, characterized in that: Preparation of the organic eutectic: two organic phase change thermal storage materials with different phase change temperatures are introduced into a water bath heated magnetic stirrer, heated in a water bath at 50°C-80°C in a sealed state until all components are completely melted, and the heating and stirring are continued for 20-50 minutes, and dried in a constant temperature drying oven at 60°C-85°C for 5-12 hours, and a white block solid is obtained after cooling, and the organic eutectic is obtained by ultrafine grinding; Preparation of the organic eutectic phase change thermal storage material: introducing a high carbon-based material and a nano thermal conductive material into the organic eutectic under stirring, adjusting the heating temperature until the organic eutectic phase change material melts, stirring for 20-50 minutes, naturally cooling in a closed dry environment at 15-25° C., and crushing after solidification to obtain a high carbon-based high thermal conductive organic eutectic phase change thermal storage material; Preparation of the composite gel-shaped inorganic phase change thermal storage material: Dissolve the first inorganic phase change material and the second inorganic phase change material, or the first inorganic phase change material, the second inorganic phase change material and the third inorganic phase change material in an appropriate amount of distilled water, stir magnetically, heat the corresponding phase change material solutions in a water bath to between 50°C and 90°C, stir the solutions until the solid is completely dissolved and the solutions become transparent, and filter the solutions to remove any solid impurities; The filtered solution is transferred to a dry sealable container, which is sealed and placed in a thermostatic bath to control the temperature of the solution, and the temperature of the solution is slowly lowered until the phase change temperature of the corresponding phase change thermal storage material is reached, and each solution is concentrated to a water content of less than 15%, and cooled to room temperature to obtain a plurality of the thermal solutions, and a high molecular polymer water-absorbing material is slowly added to the inorganic phase change thermal storage solution, and the high molecular polymer water-absorbing material is fully stirred to form a plurality of the gel-type fixed phase change materials; A plurality of the gel-type fixed phase change materials are mixed, and high carbon-based materials and nano thermal conductive materials are added. After stirring for half an hour, the mixture is placed in a constant temperature drying oven for drying, and naturally cooled in a closed dry environment at 20° C. until solidified, and then crushed to obtain a finished product.

10. A solar greenhouse, characterized in that: It comprises a greenhouse wall, which is made by stacking the phase change thermal storage blocks according to any one of claims 1 to 9.

11. A solar greenhouse according to claim 10, characterized in that: The thickness of the greenhouse wall is 400-600mm, the inner side of the greenhouse wall is painted with 200-800um nano thermal conductive paint, and the outer side of the greenhouse wall is provided with a 90mm-150mm thick extruded polystyrene insulation board.

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