CN109135678B - Room temperature phase change energy storage material and preparation method thereof - Google Patents

Room temperature phase change energy storage material and preparation method thereof Download PDF

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CN109135678B
CN109135678B CN201710458279.1A CN201710458279A CN109135678B CN 109135678 B CN109135678 B CN 109135678B CN 201710458279 A CN201710458279 A CN 201710458279A CN 109135678 B CN109135678 B CN 109135678B
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侯峰
卢竼漪
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Tianjin University
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Abstract

The invention discloses a room temperature phase change energy storage material and a preparation method thereof, wherein MgCl is added into hydroxylated carbon nano-tubes and inorganic salt simultaneously2·6H2O‑CaCl2·6H2The compound nucleating agent in the O phase-change material can generate a synergistic effect to jointly promote the nucleation of the phase-change materialThereby obviously reducing the supercooling degree of the system. The invention has the beneficial effects that: when CNTs, SrCO3、SrCl2·6H2When the introduced amount of O is 0.75g, 0.3g and 0.9g respectively, the supercooling degree of the system is only 0.6 ℃, and the system has stronger heat storage capacity and good cycle stability.

Description

Room temperature phase change energy storage material and preparation method thereof
Technical Field
The invention relates to the technical field of phase change energy storage materials, in particular to a room temperature phase change energy storage material and a preparation method thereof.
Background
The reserves of magnesium salts in Qinghai salt lake areas of China are very rich and the quality is high, but a large amount of magnesium salts are known as 'magnesium harm' because no suitable application is found. Among the magnesium salts, MgCl2·6H2O has high heat of fusion (171kJ/kg) and has been widely researched as a phase change energy storage material, but because the phase change temperature is higher (118 ℃), the O can be applied at room temperature and must be mixed with CaCl2·6H2O and the like to form a composite system. However, inorganic salt hydrates are generally applied to the field of phase change energy storage, and have the problems of large supercooling degree, poor thermal conductivity, phase separation and the like. The hydroxylated carbon nanotube has a hydroxyl group, which can be combined with ions in the phase-change material, and is beneficial to improving the wetting property between the carbon nanotube and the phase-change material; the carbon nano tube with larger specific surface area provides a larger non-uniform nucleation interface and more nucleation points for the phase change material, can promote the system to generate non-uniform nucleation, reduces the nucleation potential barrier and further reduces the supercooling degree; the carbon nano tube has good heat-conducting property, and can form a heat-conducting network with excellent performance in the phase-change material, so that the heat-conducting property of the system is improved, the system is more sensitive to temperature, and the temperature hysteresis is reduced. According to the "lattice matching principle", inorganic salts (strontium salts) and MgCl2·6H2O-CaCl2·6H2The crystal structure and lattice parameters of the O system are close to each other, so that the surface energy is reduced, the nucleation is catalyzed, and the supercooling degree is reduced. MgCl is added into the hydroxylated carbon nano-tube and the inorganic salt at the same time2·6H2O-CaCl2·6H2The O phase-change material can generate synergistic action as a composite nucleating agent to promote the nucleation of the phase-change material together, so that the supercooling degree of the system is obviously reduced.
Disclosure of Invention
The invention aims to provide a preparation method of a high-heat-conductivity and high-heat-storage room-temperature phase-change energy storage material aiming at the technical defects in the prior art.
The technical scheme adopted for realizing the purpose of the invention is as follows:
the invention is realized by the following technical scheme.
The invention relates to a preparation method of a room temperature phase change energy storage material, which comprises the following steps:
(1) respectively weighing CaCl2·6H2O and MgCl2·6H2Heating the O crystal to completely melt the mixture;
(2) magnetically stirring the system prepared in the step (2) at 60-100 ℃ for 1-3h, adding a thickening agent and a hydroxylated carbon nanotube in the stirring process, and ultrasonically dispersing at 40-50 ℃ for 1-2 h until the system is uniformly mixed;
(3) then weighing SrCl2·6H2O and SrCO3And (3) jointly used as an inorganic salt nucleating agent to be respectively added into the system prepared in the step (3), wherein: magnetically stirring for 1-3h at 60-100 ℃, and ultrasonically dispersing for 1-2 h at 40-50 ℃ to finally obtain MgCl2·6H2O-CaCl2·6H2O room temperature phase change energy storage material;
wherein: in the step (2), the hydroxylated carbon nanotube is used as a nucleating agent, and the mass fraction of the added hydroxylated carbon nanotube is 0-0.5%, namely the mass of the hydroxylated carbon nanotube is MgCl2·6H2O-CaCl2·6H2The content of the O room temperature phase change energy storage material is 0-0.5%;
SrCO in step (3)3SrCl2·6H2O and SrCO3Adding SrCO in the total mass fraction3SrCl2·6H2O and SrCO3In MgCl2·6H2O-CaCl2·6H2The O room temperature phase change energy storage material accounts for 0-5%.
Preferably, CaCl in the step (1)2·6H2O and MgCl2·6H2The O crystal is prepared by the following steps: dissolving anhydrous calcium chloride and anhydrous magnesium chloride in deionized water, preparing a nearly saturated solution at 60-100 ℃, carrying out suction filtration and purification while the solution is hot, standing for 24 hours at room temperature, and removing liquid by suction filtration to obtain high-purity CaCl2·6H2O、MgCl2·6H2O crystals;
preferably, CaCl in the step (1)2·6H2O and MgCl2·6H2The mass ratio of the O crystal is (1:5) - (5: 1).
Preferably, the thickener in step (2) is hydroxyethyl cellulose or polyacrylamide.
Preferably, SrCl in the step (3)2·6H2O and SrCO3The mass ratio is (1:5) - (5: 1).
Preferably, CaCl is contained in the reaction system2·6H2O and MgCl2·6H2The amounts of O crystals added were 71.81 wt.% and 23.94 wt.%, respectively, i.e. CaCl2·6H2O and MgCl2·6H2The quality of the O crystal is MgCl2·6H2O-CaCl2·6H271.81 wt.% and 23.94 wt.% of O room temperature phase change energy storage material, hydroxylated carbon nano tube and SrCO3And SrCl2·6H2The addition amounts of O are 0.25 wt.%, 1 wt.% and 3 wt.%, respectively, i.e. hydroxylated carbon nanotubes, SrCO3And SrCl2·6H2O in MgCl2·6H2O-CaCl2·6H2The O room temperature phase change energy storage material accounts for 0.25 wt.%, 1 wt.% and 3 wt.%.
In another aspect of the invention, there is also included a MgCl prepared by the above method2·6H2O-CaCl2·6H2And O room temperature phase change material.
Preferably, the MgCl2·6H2O-CaCl2·6H2The O room temperature phase-change material contains 0-0.5% of hydroxylated carbon nanotube nucleating agent and 0-5% of SrCl2·6H2O and SrCO3An inorganic salt nucleating agent.
Preferably, in said MgCl2·6H2O-CaCl2·6H2In O room temperature phase change material, CaCl2·6H2O and MgCl2·6H2The mass fractions of O crystal are 71.81 wt.% and 23.94 wt.%, respectively, the mass fraction of hydroxylated carbon nanotube nucleating agent is 0.25 wt.%, SrCO3Is 1 wt.%,SrCl2·6H2The mass fraction of O was 3 wt.%.
Preferably, the MgCl2·6H2O-CaCl2·6H2The phase change temperature range of the O room temperature phase change material is 18.4-24.4 ℃, and the temperature is higher than that of the O room temperature phase change material
The range of variation of the cold degree is 0.6-14.5 ℃, and the range of variation of the latent heat of phase change is 99.12-122.4J/g.
Preferably, the MgCl2·6H2O-CaCl2·6H2After the O room temperature phase change material is circularly melted and solidified for 50 times, the phase change latent heat is kept stable.
Compared with the prior art, the invention has the beneficial effects that:
(1) MgCl prepared by the process2·6H2O-CaCl2·6H2The O phase change energy storage material is a room temperature phase change energy storage material system with good applicability, and the synthesis process is simple and feasible and has strong repeatability.
(2) By this method hydroxylated carbon nanotubes are added to MgCl2·6H2O-CaCl2·6H2The hydroxylated carbon nano tube has hydroxyl groups, so that the hydroxylated carbon nano tube can be combined with ions in the phase-change material, the wetting property between the carbon nano tube and the phase-change material is improved, the carbon nano tube can be uniformly dispersed in the phase-change material for a long time, and the stability of the whole system is improved.
(3) By this method hydroxylated carbon nanotubes are added to MgCl2·6H2O-CaCl2·6H2In the O phase change material, the large specific surface area of the hydroxylated carbon nanotube provides a larger non-uniform nucleation interface and more nucleation sites for the phase change material, so that the system can be promoted to generate non-uniform nucleation, the nucleation potential barrier is reduced, and the supercooling degree is further reduced. And (3) recording a material cooling curve by using a temperature recorder, wherein when only the hydroxylated carbon nanotube is added, the addition amount is gradually increased, the supercooling degree of the system is gradually reduced, and when the addition amount is 0.75g, the supercooling degree is 9.1 ℃.
(4) The carbon nano tube has good heat-conducting property, and can form a heat-conducting network with excellent performance in the phase-change material, so that the heat-conducting property of the system is improved, the system is more sensitive to temperature, the temperature hysteresis is reduced, and the energy utilization efficiency of the phase-change material in the heat storage and heat release process is improved. And (3) recording a material cooling curve by using a temperature recorder, wherein the time for each group of samples to reach the phase change point is gradually reduced along with the gradual increase of the addition amount of the hydroxylated carbon nanotube under the condition that the initial temperature and the cooling condition are basically the same.
(5) MgCl is added into the hydroxylated carbon nano-tube and the inorganic salt at the same time2·6H2O-CaCl2·6H2The O phase-change material can generate synergistic effect as a composite nucleating agent to promote the nucleation of the phase-change material together, so that the supercooling degree of the system is obviously reduced. Recording the cooling curve of the material by a temperature recorder when CNTs and SrCO exist3、SrCl2·6H2When the introduced amounts of O are 0.75g, 0.3g and 0.9g, respectively, the degree of supercooling of the system is only 0.6 ℃.
(6) Compared with a material without the nucleating agent, the hydroxylated carbon nanotube-inorganic salt composite nucleating agent has stronger heat storage capacity and better cycle stability. As shown in FIG. 2, the phase change material introduced with 0.75g of the carbon nanotube-inorganic salt composite nucleating agent has a latent heat of phase change of 116.1J/g, and is subjected to a melting-solidification cycle 50 times, as shown in FIG. 3, with a latent heat of phase change of 113.5J/g.
Drawings
FIG. 1 is a cooling curve of the phase change energy storage system obtained in example 1;
FIG. 2 is a differential scanning calorimetry curve of the phase change energy storage system obtained in example 1;
FIG. 3 is a cooling curve of the phase change energy storage system obtained in example 2;
FIG. 4 is a differential scanning calorimetry curve of the phase change energy storage system obtained in example 2;
FIG. 5 is a cooling curve of the phase change energy storage system obtained in example 3;
FIG. 6 is a cooling curve of the phase change energy storage material obtained in example 4;
FIG. 7 is a differential scanning calorimetry curve of the phase change energy storage material obtained in example 4;
FIG. 8 is a differential scanning calorimetry curve obtained after 50 melting-solidification tests were performed on the phase change energy storage material obtained in example 4.
Detailed Description
The invention is described in further detail below with reference to the figures and specific examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1 (hydroxylated carbon nanotubes as nucleating agent)
(1) Dissolving anhydrous calcium chloride and anhydrous magnesium chloride in deionized water, preparing a nearly saturated solution at 60-100 ℃, carrying out suction filtration and purification while the solution is hot, standing for 24 hours at room temperature, and removing liquid by suction filtration to obtain high-purity CaCl2·6H2O、MgCl2·6H2O crystals;
(2) 22.5g and 7.5g of CaCl were weighed out separately2·6H2O and MgCl2·6H2Heating the O crystal in a beaker to 60-100 ℃, and keeping for 10min to completely melt the mixture;
(3) magnetically stirring the system prepared in the step (2) at 60-100 ℃ for 1-3h, adding 0.15g of hydroxyethyl cellulose as a thickening agent and 0.75g of hydroxylated carbon nano tube as a nucleating agent in the stirring process, and ultrasonically dispersing for 1-2 h at 40-50 ℃ until the system is uniformly mixed to finally obtain MgCl2·6H2O-CaCl2·6H2O room temperature phase change energy storage material.
As can be seen from FIG. 1, the supercooling degree of the phase change energy storage system obtained in example 1 is 14.5 ℃, the phase change time is 165min, as can be seen from FIG. 2, and the latent heat of phase change of the phase change energy storage system obtained in example 1 is 111.1J/g.
Example 2 (with SrCl)2·6H2O、SrCO3As nucleating agents)
(1) Dissolving anhydrous calcium chloride and anhydrous magnesium chloride in deionized water, preparing a nearly saturated solution at 60-100 ℃, carrying out suction filtration and purification while the solution is hot, standing for 24 hours at room temperature, and removing liquid by suction filtration to obtain high-purity CaCl2·6H2O、MgCl2·6H2O crystals;
(2) respectively weighing 22.5g and 7.5g of CaCl2·6H2O and MgCl2·6H2Heating the O crystal in a beaker to 60-100 ℃, and keeping for 10min to completely melt the mixture;
(3) magnetically stirring the system prepared in the step (2) at high temperature for 2 hours, adding 0.15g of thickening agent in the stirring process, and ultrasonically dispersing at high temperature for 1 hour until the system is uniformly mixed;
(4) 0.9g of SrCl is weighed out again2·6H2O and 0.3g SrCO3Respectively adding the inorganic salt nucleating agents into the system prepared in the step (3), magnetically stirring for 2 hours at high temperature, and ultrasonically dispersing for 1 hour at high temperature to finally obtain MgCl2·6H2O-CaCl2·6H2And (3) an O phase change energy storage system.
As can be seen from FIG. 3, the supercooling degree of the phase change energy storage system obtained in example 2 is 7.8 ℃, the phase change time is 71min, as can be seen from FIG. 4, and the latent heat of phase change of the phase change energy storage system obtained in example 2 is 122.4J/g.
Example 3 (hydroxylated carbon nanotubes as nucleating agent and varying the amount of hydroxylated carbon nanotubes added)
(1) Dissolving anhydrous calcium chloride and anhydrous magnesium chloride in deionized water, preparing a nearly saturated solution at 60-100 ℃, carrying out suction filtration and purification while the solution is hot, standing for 24 hours at room temperature, and removing liquid by suction filtration to obtain high-purity CaCl2·6H2O、MgCl2·6H2O crystals;
(2) 22.5g and 7.5g of CaCl were weighed out separately2·6H2O and MgCl2·6H2Heating the O crystal in a beaker to 60-100 ℃, and keeping for 10min to completely melt the mixture;
(3) magnetically stirring the system prepared in the step (2) at the temperature of 60-100 ℃ for 1-3h, adding 0.15g of hydroxyethyl cellulose as a thickening agent and 0.00g, 0.15g, 0.30g, 0.45g, 0.60g and 0.75g of hydroxylated carbon nano tube as a nucleating agent in the stirring process, and ultrasonically dispersing at the temperature of 40-50 ℃ for 1-2 h until the system is uniformly mixed to finally obtain MgCl2·6H2O-CaCl2·6H2O room temperature phase change energy storage material.
As can be seen from FIG. 5, when 0.00g, 0.15g, 0.30g, 0.45g, 0.60g, 0.75g of CNTs are added, the supercooling degree of the system gradually decreases, corresponding to 15, 14.5, 13.6, 9.4 and 9.1 ℃, respectively, and it can be seen that the supercooling degree of the phase change material gradually decreases with the increase of the mass fraction of the hydroxylated carbon tube, which indicates that the hydroxylated carbon tube functions as a nucleating agent.
Example 4
(1) Dissolving anhydrous calcium chloride and anhydrous magnesium chloride in deionized water, preparing a nearly saturated solution at 60-100 ℃, carrying out suction filtration and purification while the solution is hot, standing for 24 hours at room temperature, and removing liquid by suction filtration to obtain high-purity CaCl2·6H2O、MgCl2·6H2O crystals;
(2) 22.5g and 7.5g of CaCl were weighed out separately2·6H2O and MgCl2·6H2Heating the O crystal in a beaker to 60-100 ℃, and keeping for 10min to completely melt the mixture;
(3) magnetically stirring the system prepared in the step (2) at 60-100 ℃ for 1-3h, adding 0.15g of hydroxyethyl cellulose as a thickening agent and 0.75g of hydroxylated carbon nanotube as a nucleating agent in the stirring process, and ultrasonically dispersing at 40-50 ℃ for 1-2 h until the system is uniformly mixed;
(4) 0.9g of SrCl is weighed out again2·6H2O and 0.3g SrCO3Respectively adding the inorganic salt nucleating agents into the system prepared in the step (3), magnetically stirring for 1-3h at the temperature of 60-100 ℃, and ultrasonically dispersing for 1-2 h at the temperature of 40-50 ℃ to finally obtain MgCl2·6H2O-CaCl2·6H2O room temperature phase change energy storage material.
From FIG. 6, the phase transition temperature of the system obtained in example 4 was 19.9 ℃, the supercooling degree was 0.6 ℃, and the phase transition time was 41 min. The latent heat of phase change of the system obtained in example 4 from FIG. 7 was 116.1J/g.
The above samples were subjected to melting-solidification test 50 times without external disturbance, and it can be seen from FIG. 8 that the latent heat of phase change of the system after 50 times of melting-solidification was 113.5J/g.
Example 5
(1) Dissolving anhydrous calcium chloride and anhydrous magnesium chloride in deionized water, preparing a nearly saturated solution at 60-100 ℃, and feeding the solution while the solution is hotPerforming suction filtration and purification, standing for 24 hours at room temperature, and removing liquid by suction filtration to obtain high-purity CaCl2·6H2O、MgCl2·6H2O crystals;
(2) 22.5g and 7.5g of CaCl were weighed out separately2·6H2O and MgCl2·6H2Heating the O crystal in a beaker to 60-100 ℃, and keeping for 10min to completely melt the mixture;
(3) magnetically stirring the system prepared in the step (2) at 60-100 ℃ for 1-3h, adding 0.15g of carboxymethyl cellulose as a thickening agent and 0.75g of hydroxylated carbon nano tube as a nucleating agent in the stirring process, and ultrasonically dispersing at 40-50 ℃ for 1-2 h until the system is uniformly mixed;
(4) 0.9g of SrCl is weighed out again2·6H2O and 0.3g SrCO3Respectively adding the inorganic salt nucleating agents into the system prepared in the step (3), magnetically stirring for 1-3h at the temperature of 60-100 ℃, and ultrasonically dispersing for 1-2 h at the temperature of 40-50 ℃ to finally obtain MgCl2·6H2O-CaCl2·6H2O room temperature phase change energy storage material.
The test results show that MgCl is obtained in example 32·6H2O-CaCl2·6H2The O room temperature phase change energy storage material can not keep a uniform and stable state for a long time in the cooling process, and the delamination phenomenon occurs, so that the carboxymethyl cellulose in the system is not a proper thickening agent.
Example 6
(1) Dissolving anhydrous calcium chloride and anhydrous magnesium chloride in deionized water, preparing a nearly saturated solution at 60-100 ℃, carrying out suction filtration and purification while the solution is hot, standing for 24 hours at room temperature, and removing liquid by suction filtration to obtain high-purity CaCl2·6H2O、MgCl2·6H2O crystals;
(2) 22.5g and 7.5g of CaCl were weighed out separately2·6H2O and MgCl2·6H2Heating the O crystal in a beaker to 60-100 ℃, and keeping for 10min to completely melt the mixture;
(3) magnetically stirring the system prepared in the step (2) at 60-100 ℃ for 1-3h, adding 0.15g of hydroxyethyl cellulose as a thickening agent and 0.45g of hydroxylated carbon nano tube as a nucleating agent in the stirring process, and ultrasonically dispersing at 40-50 ℃ for 1-2 h until the system is uniformly mixed;
(4) 0.9g of SrCl is weighed out again2·6H2O and 0.3g SrCO3Respectively adding the inorganic salt nucleating agents into the system prepared in the step (3), magnetically stirring for 2 hours at high temperature, and ultrasonically dispersing for 1-2 hours at 40-50 ℃ to finally obtain MgCl2·6H2O-CaCl2·6H2O room temperature phase change energy storage material.
The experimental results show that MgCl2·6H2O-CaCl2·6H2The phase change temperature of the O room temperature phase change energy storage material is 22.1 ℃, the supercooling degree is 5.8 ℃, and the phase change time is 65 min.
Example 7
(1) Dissolving anhydrous calcium chloride and anhydrous magnesium chloride in deionized water, preparing a nearly saturated solution at 60-100 ℃, carrying out suction filtration and purification while the solution is hot, standing for 24 hours at room temperature, and removing liquid by suction filtration to obtain high-purity CaCl2·6H2O、MgCl2·6H2O crystals;
(2) 22.5g and 7.5g of CaCl were weighed out separately2·6H2O and MgCl2·6H2Heating the O crystal in a beaker to 60-100 ℃, and keeping for 10min to completely melt the mixture;
(3) magnetically stirring the system prepared in the step (2) at 60-100 ℃ for 1-3h, adding 0.15g of hydroxyethyl cellulose as a thickening agent and 0.5g of hydroxylated carbon nano tube as a nucleating agent in the stirring process, and ultrasonically dispersing at 40-50 ℃ for 1-2 h until the system is uniformly mixed;
(4) 0.75g of SrCl is weighed out again2·6H2O and 0.5g SrCO3Respectively adding the inorganic salt nucleating agents into the system prepared in the step (3), magnetically stirring for 1-3h at the temperature of 60-100 ℃, and ultrasonically dispersing for 1-2 h at the temperature of 40-50 ℃ to finally obtain MgCl2·6H2O-CaCl2·6H2O room temperature phase change energy storage material.
The experimental results show that MgCl2·6H2O-CaCl2·6H2The phase change temperature of the O room temperature phase change energy storage material is 20.3 ℃, and the supercooling degree is 1.8 DEG CThe phase transition time was 54 min.
Example 8
(1) Dissolving anhydrous calcium chloride and anhydrous magnesium chloride in deionized water, preparing a nearly saturated solution at 60-100 ℃, carrying out suction filtration and purification while the solution is hot, standing for 24 hours at room temperature, and removing liquid by suction filtration to obtain high-purity CaCl2·6H2O、MgCl2·6H2O crystals;
(2) 22.5g and 7.5g of CaCl were weighed out separately2·6H2O and MgCl2·6H2Heating the O crystal in a beaker to 60-100 ℃, and keeping for 10min to completely melt the mixture;
(3) magnetically stirring the system prepared in the step (2) at 60-100 ℃ for 1-3h, adding 0.15g of hydroxyethyl cellulose as a thickening agent and 0.75g of hydroxylated carbon nanotube as a nucleating agent in the stirring process, and ultrasonically dispersing at 40-50 ℃ for 1-2 h until the system is uniformly mixed;
(4) 0.3g of SrCl is weighed again2·6H2O and 0.1g SrCO3Respectively adding the inorganic salt nucleating agents into the system prepared in the step (3), magnetically stirring for 1-3h at the temperature of 60-100 ℃, and ultrasonically dispersing for 1-2 h at the temperature of 40-50 ℃ to finally obtain MgCl2·6H2O-CaCl2·6H2O room temperature phase change energy storage material.
The experimental results show that MgCl2·6H2O-CaCl2·6H2The phase-change temperature of the O room temperature phase-change energy storage material is 22.8 ℃, the supercooling degree is 7.1 ℃, and the phase-change time is 72 min.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (10)

1. A preparation method of a room temperature phase change energy storage material is characterized by comprising the following steps:
(1) respectively weighing CaCl2∙6H2O and MgCl2∙6H2O crystals, addHeating to completely melt the mixture;
(2) magnetically stirring the system prepared in the step (1) at 60-100 ℃ for 1-3h, adding a thickening agent and a hydroxylated carbon nanotube in the stirring process, and ultrasonically dispersing for 1-2 h at 40-50 ℃ until the system is uniformly mixed, wherein the thickening agent is hydroxyethyl cellulose;
(3) then weighing SrCl2∙6H2O and SrCO3And (3) jointly used as an inorganic salt nucleating agent to be respectively added into the system prepared in the step (2), wherein: magnetically stirring for 1-3h at 60-100 ℃, and ultrasonically dispersing for 1-2 h at 40-50 ℃ to finally obtain MgCl2∙6H2O-CaCl2∙6H2O room temperature phase change energy storage material;
wherein: in the step (2), the hydroxylated carbon nanotube is used as a nucleating agent, and the mass fraction of the added hydroxylated carbon nanotube is 0-0.5% and cannot be 0, namely the mass of the hydroxylated carbon nanotube is MgCl2∙6H2O-CaCl2∙6H2The O room temperature phase change energy storage material accounts for 0-0.5% and cannot be 0;
SrCl in step (3)2∙6H2O and SrCO3In MgCl2∙6H2O-CaCl2∙6H2The O room temperature phase change energy storage material accounts for 0-5% and cannot be 0.
2. The method for preparing the room temperature phase change energy storage material as claimed in claim 1, wherein the CaCl in the step (1)2∙6H2O and MgCl2∙6H2The O crystal is prepared by the following steps: dissolving anhydrous calcium chloride and anhydrous magnesium chloride in deionized water, preparing a nearly saturated solution at 60-100 ℃, carrying out suction filtration and purification while the solution is hot, standing for 24 hours at room temperature, and removing liquid by suction filtration to obtain high-purity CaCl2∙6H2O、MgCl2∙6H2And (4) O crystals.
3. The method for preparing the room temperature phase change energy storage material as claimed in claim 1, wherein the CaCl in the step (1)2∙6H2O and MgCl2∙6H2Mass ratio of O crystalIs (1:5) - (5: 1).
4. The method for preparing the room temperature phase change energy storage material as claimed in claim 1, wherein the SrCl in the step (3)2∙6H2O and SrCO3The mass ratio is (1:5) - (5: 1).
5. The method for preparing the room temperature phase change energy storage material as claimed in claim 1, wherein CaCl in the system2∙6H2O and MgCl2∙6H2The amounts of O crystals added were 71.81 wt.% and 23.94 wt.%, respectively, i.e. CaCl2∙6H2O and MgCl2∙6H2The quality of the O crystal is MgCl2∙6H2O-CaCl2∙6H271.81 wt.% and 23.94 wt.% of O room temperature phase change energy storage material, hydroxylated carbon nano-tube, SrCO3And SrCl2∙6H2The addition of O is 0.25 wt.%, 1 wt.% and 3 wt.%, respectively, i.e. hydroxylated carbon nanotubes, SrCO3And SrCl2∙6H2O in MgCl2∙6H2O-CaCl2∙6H2The O room temperature phase change energy storage material accounts for 0.25 wt.%, 1 wt.% and 3 wt.%.
6. MgCl prepared by the preparation method of the room-temperature phase-change energy storage material according to claim 12∙6H2O-CaCl2∙6H2And O room temperature phase change material.
7. The MgCl of claim 62∙6H2O-CaCl2∙6H2O room temperature phase change material, characterized in that the MgCl is2∙6H2O-CaCl2∙6H2The O room temperature phase-change material contains 0-0.5% but not 0 mass percent of hydroxylated carbon nanotube nucleating agent and 0-5% but not 0 mass percent of SrCl2∙6H2O and SrCO3An inorganic salt nucleating agent.
8.The MgCl of claim 62∙6H2O-CaCl2∙6H2O room temperature phase change material, characterized in that in the MgCl2∙6H2O-CaCl2∙6H2In O room temperature phase change material, CaCl2∙6H2O and MgCl2∙6H2The mass fractions of O crystal are 71.81 wt.% and 23.94 wt.%, respectively, the mass fraction of hydroxylated carbon nanotube nucleating agent is 0.25 wt.%, SrCO3Is 1 wt.%, SrCl2∙6H2The mass fraction of O was 3 wt.%.
9. The MgCl of claim 62∙6H2O-CaCl2∙6H2O room temperature phase change material, characterized in that the MgCl is2∙6H2O-CaCl2∙6H2The phase change temperature range of the O room temperature phase change material is 18.4-24.4 ℃, the supercooling degree change range is 0.6-14.5 ℃, and the phase change latent heat change range is 99.12-122.4J/g.
10. The MgCl of claim 62∙6H2O-CaCl2∙6H2O room temperature phase change material, characterized in that the MgCl is2∙6H2O-CaCl2∙6H2After the O room temperature phase change material is circularly melted and solidified for 50 times, the phase change latent heat is kept stable.
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