A magnesium cement-based phase change building material, a preparation method thereof and application thereof

Abstract

The application discloses a preparation method of a magnesium cement-based phase change building material and application thereof. The method comprises the following steps: solidifying MOC or MOS slurry into concrete, crushing the concrete into particles, mixing the particles with MPC slurry to form MPC building material containing concrete particles, soaking the MPC building material in water to make the internal concrete particles broken and leached to form interconnected pores, immersing the building material with interconnected pores into phase change material to form particle phase change building material with the interconnected pores filled with the phase change material, and mixing the particle phase change building material with MPC slurry to form MPC phase change building material with a protective shell. The phase change building material prepared by the method has a protective shell, can effectively prevent the phase change material from leaking, has interconnected pores formed in the inside, and can make the phase change material uniform. The method can be regarded as a combination of a direct penetration method and an encapsulation method, is simple in operation, and is low in cost. The phase change material and the encapsulation material are formed by the same material, so that the MPC phase change building material has good workability.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of building materials, and particularly relates to a magnesium cement-based phase change building material and a preparation method and application thereof. BACKGROUND

[0002] The phase change material is a phase change material in a wall material at a specific temperature, which changes in phase state and simultaneously absorbs or releases heat, so as to store heat by using latent heat and adjust indoor temperature. The phase change material is applied to a building envelope, so as to solve the problem of small heat capacity of ordinary light materials used in modern buildings, increase the heat storage capacity and thermal inertia of the building envelope, and due to the large phase change latent heat of the phase change material, a small amount of the phase change material can store a large amount of heat, and at the same time, the temperature change range of the indoor and outdoor of the building is reduced, which plays a certain role in reducing the design of the air conditioning system, and can achieve the purposes of energy saving and improving thermal comfort. In the field of building energy saving, the selection of the phase change material is crucial. Starting from the actual situation and the thermal physical characteristics and economic aspects of the phase change material, the best heat storage effect of the phase change material is achieved, and the price is cheap and easy to popularize.

[0003] According to the phase change form of the phase change material, the phase change material can be divided into solid-solid, solid-liquid, solid-gas and liquid-gas energy storage phase change materials. The research on the phase change material is also roughly concentrated in these directions. For example, the Chinese invention patent CN111971364A discloses a solid-solid phase change material, which is a polyether or polyester-epoxy polymer (PEEP) composition. The composition contains the product of the reaction of a polyepoxide compound and a polyol composition, which can enable formulators to manage thermal energy changes in a number of practical applications, but the preparation of the composition is relatively complex. The Chinese invention patent CN104529321A discloses a layered composite phase change energy storage building material. The layered composite phase change energy storage material is prepared by using a microwave vacuum adsorption method with bentonite and alcohol, and then the layered composite phase change energy storage material, Portland cement and other materials are uniformly compounded by using a physical blending method, and a layered composite phase change energy storage building material is prepared by molding and curing. However, this method is also relatively complicated to operate, and the performance of the phase change material is not very good using ordinary Portland cement.

[0004] The existing phase change energy storage building material is mainly based on traditional Portland cement. The anti-corrosion performance of the traditional Portland cement to inorganic water and salt is poor, so that the phase change material needs to be packaged or shaped, and it is difficult to directly mix or penetrate the phase change material into the base material to maintain long-term use performance.

[0005] Therefore, it is urgent to provide a preparation method of a phase change building material to solve these problems. SUMMARY

[0006] The application provides a magnesium cement-based phase change building material and a preparation method and application thereof, and aims to solve the problems of poor compatibility of traditional building materials and phase change building materials, easy leakage of phase change materials and failure caused by long-term use. The preparation method comprises the following steps: forming concrete after solidification of slurry A, crushing and screening to obtain concrete particles, mixing and solidifying the concrete particles and MPC slurry to form MPC building material containing concrete particles, soaking the MPC building material containing concrete particles in water to decompose the concrete particles, leaching out and forming interconnected pores in the interior, immersing the building material with interconnected pores in phase change material, and forming X-MPC phase change building material containing phase change material in the interconnected pores.

[0007] Further, the X-MPC phase change building material is mixed with MPC slurry and then solidified to form MPC phase change building material with an outer protective shell.

[0008] Further, the slurry A comprises any one of MOC slurry and MOS slurry.

[0009] Further, the solidification of the slurry A comprises drying at 10-35 DEG C for 3-7 days and then baking at 30-80 DEG C for 3-24 h.

[0010] Further, the MOC slurry is prepared by mixing magnesium chloride and active magnesium oxide.

[0011] Further, the MOS slurry is prepared by mixing magnesium sulfate solution and active magnesium oxide.

[0012] Further, the mixing and solidification of the concrete particles and MPC slurry comprises injecting a mold and keeping at 10-35 DEG C for 1-6 h.

[0013] Further, the MPC slurry is prepared by mixing dead-burned magnesium oxide, ammonium dihydrogen phosphate and borax according to a mass ratio of 1.5:1:0.1, ball milling to prepare MPC dry powder mixture, and adding 0.65 times of water in the MPC dry powder mixture.

[0014] Further, the mixing and solidification of the X-MPC phase change building material and MPC slurry comprises keeping at 10-35 DEG C for 1-6 h.

[0015] Further, the MPC building material containing concrete particles is soaked in water for 7-30 days to decompose the concrete particles and leach out to form interconnected pores in the interior.

[0016] Further, the phase change material comprises any one of calcium chloride and magnesium chloride or a combination of the two.

[0017] The magnesium cement-based phase change building material prepared by the preparation method and the application thereof in the field of building are provided.

[0018] Compared with the prior art, the present application has the beneficial effects at least in that:

[0019] 1. The porous material formed without reacting with the phase change material makes the phase change material evenly distributed, enhances the thermal conductivity, and sets a protective layer of the same material outside the hydrated phase change particles, forming M-S / C-MPC particles, effectively preventing the phase change material from leaking.

[0020] 2. The cementitious material is consistent with the phase change material and the encapsulating material, has good workability, and the same material is more conducive to forming a whole, improving the supercooling and phase separation problems of the phase change material.

[0021] 3. The present application can be considered as a perfect combination of direct incorporation method and encapsulation method based on the same material, which is simple in actual operation and low in economic cost. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0023] Figure 1 is a schematic diagram of forming a connected hole in the MPC building material in Embodiment 1 of the present application. DETAILED DESCRIPTION

[0024] The present application will be more fully understood by the following detailed description taken in connection with the accompanying drawings. Detailed embodiments of the present application are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the present application, which can be embodied in various forms. Therefore, specific functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to employ the present application in virtually any appropriate detailed embodiment. The present application is based on the following detailed description.

[0025] Embodiment 1

[0026] This embodiment provides a magnesium cement-based phase change building material, specifically, the preparation method is as follows:

[0027] 1. Dissolve magnesium chloride in water to prepare a 25% MgCl2 solution, and mix and stir with active magnesium oxide powder (active 60%) to form an MOC slurry.

[0028] 2. The above MOC slurry is dried at room temperature (10-35°C) for 3 days, and then dried at 50°C for 6h to obtain dried MOC building material.

[0029] 3. The above MOC building material is crushed and sieved to obtain MOC particles of 0.2-0.6cm.

[0030] 4. Burned magnesium oxide, ammonium dihydrogen phosphate, and borax are mixed uniformly in a mass ratio of 1.5:1:0.1 to form a dry MPC powder mixture, and water is added to the dry MPC powder mixture in an amount of 0.65 times the mass of the dry MPC powder mixture to form a MPC slurry.

[0031] 5. The MOC particles in step 3 are added to the above MPC slurry to form a uniformly mixed MPC concrete slurry, which is injected into a mold and maintained at 25°C for 6h to form a MPC building material containing MOC particles.

[0032] 6. The above MPC building material containing MOC particles is soaked in water for 7 days to allow the MOC particles inside the MPC building material to decompose and leach out, and the pore walls between the particles to communicate with each other to form interconnected pores inside the MPC building material.

[0033] Referring to Figure 1 It can be seen that the MOC particles inside the MPC building material decompose and leach out, and the pore walls between the MOC particles communicate with each other to form interconnected pores.

[0034] 7. The above MPC building material with interconnected pores inside is immersed in a mixed phase change solution of calcium chloride (CaCl2·6H2O) and magnesium chloride (MgCl2·6H2O) to fill the interconnected pores inside with the phase change material, thereby forming an X-MPC phase change building material containing the phase change material.

[0035] 8. Burned magnesium oxide, ammonium dihydrogen phosphate, and borax are mixed uniformly in a mass ratio of 1.5:1:0.1, and water is added to the mixture to form a magnesium cement-based slurry. The X-MPC is immersed in the above magnesium cement-based slurry, and maintained at 25°C for 4h to form an M-C-MPC phase change building material with a protective layer on the outer layer of the hydrated phase change particles.

[0036] Example 2

[0037] This example provides a magnesium cement-based phase change building material, and the preparation method is as follows:

[0038] 1. Magnesium sulfate is dissolved in water to prepare a MgSO4 solution with a concentration of 25%, and is mixed and stirred uniformly with active magnesium oxide powder (active 60%) to form a MOS slurry.

[0039] 2. The above MOS slurry is cured at room temperature (10-35°C) for 7 days, and then mixed dry at 50°C for 6h to obtain a dried MOS building material.

[0040] 3. The above MOS building material is crushed and sieved to obtain MOS particles of 0.2-0.6cm.

[0041] 4. Burned magnesium oxide, ammonium dihydrogen phosphate and borax are mixed uniformly in a mass ratio of 1.5:1:0.1 to form a dry MPC powder mixture, and water is added to the dry MPC powder mixture to form a MPC slurry.

[0042] 5. The MOS particles in step 3 are mixed into the above MPC slurry to form a MPC concrete slurry, which is injected into a mold and kept at 25°C for 6h to form a MPC building material containing MOS particles.

[0043] 6. The above MPC building material containing MOS particles is soaked in water for 10 days to allow the MOS particles inside to decompose and leach out, and the pore walls between the particles to connect to form interconnected pores in the MPC building material.

[0044] 7. The MPC building material with interconnected pores is immersed in a mixed phase phase change solution of calcium chloride (CaCl2·6H2O) and magnesium chloride (MgCl2·6H2O) to fill the internal pores with phase change material to form an X-MPC phase change building material containing phase change material.

[0045] 8. Burned magnesium oxide, ammonium dihydrogen phosphate and borax are mixed uniformly in a mass ratio of 1.5:1:0.1, and water is added to form a slurry, and the above X-MPC phase change building material is immersed in the MPC slurry, and kept at 20°C for 6h to form an MPC phase change building material with an outer protective layer.

[0046] Example 3

[0047] This example provides a magnesium cement-based phase change building material, specifically, the preparation method is as follows:

[0048] 1. Magnesium sulfate is dissolved in water to prepare a MgSO4 solution with a concentration of 25%, and is mixed and stirred uniformly with active magnesium oxide powder (active 60%) to form a MOS slurry.

[0049] 2. The above MOS slurry is cured at room temperature (10-35°C) for 7 days, and then mixed dry at 30°C for 24h to obtain a dried MOS building material.

[0050] 3. The above MOS building material is crushed and sieved to obtain MOS particles of 0.2-0.6cm.

[0051] 4. Mix heavy-burned magnesium oxide, ammonium dihydrogen phosphate, borax in a mass ratio of 1.5:1:0.1, and uniformly ball mill to prepare MPC dry powder mixture. Add 0.65 times the mass of water to the MPC dry powder mixture to form MPC slurry.

[0052] 5. Mix the MOS particles in step 3 into the MPC slurry described above to form MPC concrete slurry, and inject the MPC concrete slurry into a mold. Keep the mold at 35°C for 1 h to form MPC building material containing MOS particles.

[0053] 6. Soak the MPC building material containing MOS particles described above in water for 25 days to allow the MOS particles inside the MPC building material to decompose and leach out, and allow the pore walls between the particles to be connected to each other to form interconnected pores inside the MPC building material.

[0054] 7. Immerse the MPC building material having interconnected pores inside in a single-phase phase change solution of calcium chloride (CaCl2·6H2O) to fill the pores with the phase change material to form X-MPC phase change building material containing the phase change material.

[0055] 8. Mix heavy-burned magnesium oxide, ammonium dihydrogen phosphate, and borax in a mass ratio of 1.5:1:0.1, and uniformly ball mill to prepare MPC dry powder mixture. Add water to the mixture to form slurry, and immerse the X-MPC phase change building material described above in the MPC slurry. Keep the slurry at 10°C for 4 h to form MPC phase change building material having an outer protective layer.

[0056] Example 4

[0057] This example provides a magnesium cement-based phase change building material, and specifically, the preparation method is as follows:

[0058] 1. Dissolve magnesium sulfate in water to prepare a MgSO4 solution having a concentration of 25%, and mix and stir the solution with active magnesium oxide powder (active 60%) to form MOS slurry.

[0059] 2. Cure the MOS slurry described above at room temperature (10-35°C) for 7 days, and then dry the MOS building material at 80°C for 3 h to obtain dried MOS building material.

[0060] 3. Crush the MOS building material described above to obtain MOS particles having a size of 0.2-0.6 cm.

[0061] 4. Mix heavy-burned magnesium oxide, ammonium dihydrogen phosphate, and borax in a mass ratio of 1.5:1:0.1, and uniformly ball mill to prepare MPC dry powder mixture. Add 0.65 times the mass of water to the MPC dry powder mixture to form MPC slurry.

[0062] 5. The MPC slurry is mixed with the MOS particles of step 3 to form a MPC concrete slurry, which is injected into a mold and kept at 10°C for 6 hours to form a MPC building material containing MOS particles.

[0063] 6. The MPC building material containing MOS particles is soaked in water for 30 days to decompose and leach the MOS particles inside and connect the pore walls between the particles to form interconnected pores inside the MPC building material.

[0064] 7. The MPC building material with interconnected pores is immersed in a single-phase phase change solution of magnesium chloride (MgCl2·6H2O) to fill the pores with the phase change material to form an X-MPC phase change building material containing the phase change material.

[0065] 8. Burnt magnesium oxide, ammonium dihydrogen phosphate and borax are mixed in a mass ratio of 1.5:1:0.1, water is added to form a slurry, and the X-MPC phase change building material is immersed in the MPC slurry and kept at 35°C for 1 hour to form an MPC phase change building material with an outer protective layer.

[0066] The MPC phase change building material with a protective layer prepared in Examples 1-4 is used in the field of construction. Since the phase change material is uniformly distributed in the interconnected pores inside, and more importantly, a protective shell is formed outside the hydrated phase change particles, it has good anti-leakage performance, and significantly improves the thermal conductivity of the MPC phase change building material. Compared with other capsule methods, the cementitious material in the present application is consistent with the phase change material and the protective shell material, so that the finally formed phase change building material has good workability and is more conducive to forming a whole. The method for preparing the phase change building material in the present application can be regarded as a combination of direct penetration and encapsulation. The MOC particles can be dissolved and leached in water to form interconnected pores inside the MPC building material. Compared with ordinary Portland cement, magnesium cement has higher strength, thermal conductivity and density. It is easier to form interconnected pores inside using the method of the present application, and the pore walls of the interconnected pores inside are fine and not easy to leak. The phase change material is well combined with the building substrate.

[0067] Although the present application has been described with reference to the illustrative embodiments, it will be understood by those skilled in the art that various other changes, omissions and / or additions can be made without departing from the spirit and scope of the present application. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the present application without departing from the scope thereof. Therefore, it is intended that the present application not be limited to the disclosed embodiments for carrying out this application, but that the present application will include all embodiments falling within the scope of the appended claims.

Claims

1. A method for preparing a magnesium cement-based phase change building material, characterized by, The method comprises: forming concrete after curing of the slurry A, crushing and screening the concrete to obtain concrete particles, mixing the concrete particles with MPC slurry to form MPC building materials containing concrete particles, soaking the MPC building materials containing concrete particles in water to decompose the concrete particles and leach out to form interconnected pores inside, immersing the building materials with interconnected pores in phase change materials to form X-MPC phase change building materials containing phase change materials in the interconnected pores.

2. The method of producing a magnesium cement-based phase change building material according to claim 1, characterized in that: The X-MPC phase change building materials are mixed with MPC slurry and cured to form MPC phase change building materials with an outer protective shell.

3. The method of producing a magnesium cement-based phase change building material according to claim 2, characterized in that: The slurry A comprises any one of MOC slurry and MOS slurry. The curing of the slurry A comprises drying at 10-35℃ for 3-7 days and then baking at 30-80℃ for 3-24h.

4. The method of producing a magnesium cement-based phase change building material according to claim 3, characterized in that: The MOC slurry is prepared by mixing magnesium chloride and active magnesium oxide. The MOS slurry is prepared by mixing magnesium sulfate solution and active magnesium oxide.

5. The method of making a magnesium cement-based phase change building material according to claim 1, wherein: The mixing and curing of the concrete particles with MPC slurry comprises injecting a mold and keeping at 10-35℃ for 1-6h.

6. The method of making a magnesium cement-based phase change building material according to claim 2, wherein: The MPC slurry is prepared by mixing dead-burned magnesium oxide, ammonium dihydrogen phosphate and borax at a mass ratio of 1.5:1:0.1, ball milling to obtain MPC dry powder mixture, and adding 0.65 times of water to the MPC dry powder mixture. The mixing and curing of the X-MPC phase change building materials with MPC slurry comprises keeping at 10-35℃ for 1-6h.

7. The method of producing a magnesium cement-based phase change building material according to claim 6, characterized in that: The MPC building materials containing concrete particles are soaked in water for 7-30 days to decompose the concrete particles and leach out to form interconnected pores inside.

8. The method of producing a magnesium cement-based phase change building material according to claim 7, characterized in that: The phase change materials comprise any one of calcium chloride and magnesium chloride or a combination of the two.

9. The magnesium cement-based phase change building material prepared by the method of any one of claims 1-8.

10. The magnesium cement-based phase change building material of claim 9 for use in the field of construction.

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