Sodium hydroxide hydrate phase change material and preparation method thereof

Abstract

The invention belongs to the technical field of phase change materials, and discloses a sodium hydroxide hydrate phase change material and a preparation method thereof. The phase change material comprises the following raw materials in parts by mass: 35-50 parts of sodium hydroxide, 0.5-3 parts of a crystallization nucleating agent or a crystallization nucleating agent precursor and 50-65 parts of water, the crystallization nucleating agent comprises at least one of ferrous hydroxide, cobalt hydroxide, manganese hydroxide, chromium hydroxide and strontium hydroxide; the crystal nucleating agent precursor comprises at least one of ferrite, cobalt salt, manganese salt, chromium salt and strontium salt. According to the preparation method, ferrous salt, cobalt salt, manganese salt, chromium salt, strontium salt and other inorganic salts are used as crystallization nucleating agent precursors and can react with sodium hydroxide to generate hydroxides, ferrous hydroxide and other hydroxides have a good crystallization nucleating effect on sodium hydroxide hydrate, and the prepared phase change material has the advantages that the freeze-thaw cycle stability (gt; the phase change enthalpy is high (180J / g); and the method is environment-friendly and non-toxic.

Description

Technical Field

[0001] The invention relates to the technical field of phase change materials, and in particular to a sodium hydroxide hydrate phase change material and a preparation method thereof. Background Art

[0002] The melting point of sodium hydroxide hydrate with a solid content of 40-50% is 5-15°C. It has high phase change enthalpy and low cost, and is a potential high-performance phase change material. However, sodium hydroxide hydrate is difficult to nucleate and has poor freeze-thaw cycle stability. Currently, it has only been found that adding hexavalent chromate can make sodium hydroxide hydrate have a good nucleation effect. However, hexavalent chromate is highly toxic and highly carcinogenic, and should not be added to sodium hydroxide hydrate, which undoubtedly limits the development and application of sodium hydroxide hydrate phase change materials. Summary of the invention

[0003] The object of the present invention is to provide a sodium hydroxide hydrate phase change material and a preparation method thereof, so as to solve the problem that the sodium hydroxide hydrate phase change material cannot be applied on a large scale due to its difficulty in nucleation and poor freeze-thaw cycle stability.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a sodium hydroxide hydrate phase change material, comprising the following raw materials in parts by mass: 35 to 50 parts of sodium hydroxide, 0.5 to 3 parts of a crystal nucleating agent or a crystal nucleating agent precursor, and 50 to 65 parts of water;

[0006] Wherein, the crystal nucleating agent comprises at least one of ferrous hydroxide, cobalt hydroxide, manganese hydroxide, chromium hydroxide and strontium hydroxide;

[0007] The crystal nucleating agent precursor includes at least one of ferrous salt, cobalt salt, manganese salt, chromium salt and strontium salt.

[0008] Preferably, in the sodium hydroxide hydrate phase change material, the ferrous salt comprises ferrous chloride and / or ferrous sulfate, the cobalt salt comprises cobalt chloride and / or cobalt sulfate, the manganese salt comprises manganese chloride and / or manganese sulfate, the chromium salt comprises chromium trichloride, and the strontium salt comprises strontium chloride.

[0009] Preferably, in the sodium hydroxide hydrate phase change material, the sodium hydroxide hydrate phase change material further comprises 2 to 10 parts of a phase change temperature regulator.

[0010] Preferably, in the sodium hydroxide hydrate phase change material, the phase change temperature regulator comprises one or more of sodium chloride, potassium chloride, sodium nitrate and potassium nitrate.

[0011] Preferably, in the sodium hydroxide hydrate phase change material, the sodium hydroxide hydrate phase change material further comprises 2 to 5 parts of a thickener.

[0012] Preferably, in the sodium hydroxide hydrate phase change material, the thickener is attapulgite.

[0013] Preferably, in the sodium hydroxide hydrate phase change material, the sodium hydroxide hydrate phase change material further includes 1 to 6 parts of a thermal conductive material.

[0014] Preferably, in the sodium hydroxide hydrate phase change material, the thermally conductive material comprises expanded graphite and / or flake graphite.

[0015] The present invention also provides a method for preparing the sodium hydroxide hydrate phase change material, comprising the following steps:

[0016] Mixing sodium hydroxide, a crystal nucleating agent and water to obtain a sodium hydroxide hydrate phase change material;

[0017] Alternatively, the preparation method comprises the following steps:

[0018] Sodium hydroxide, a crystal nucleating agent precursor and water are mixed to carry out double decomposition reaction to obtain a sodium hydroxide hydrate phase change material.

[0019] Preferably, in the preparation method, the temperature of the mixture of the sodium hydroxide, the crystal nucleating agent and water and the double decomposition reaction is independently 10 to 60° C., the rotation speed is independently 10 to 100 rpm, and the time is independently 10 to 30 min.

[0020] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0021] The sodium hydroxide hydrate phase change material of the present invention utilizes inorganic salts such as ferrous salts, cobalt salts, manganese salts, chromium salts and strontium salts as crystal nucleating agent precursors, which can react with sodium hydroxide to generate hydroxides, or directly utilizes hydroxides such as ferrous hydroxide, cobalt hydroxide, manganese hydroxide, chromium hydroxide or strontium hydroxide, and the obtained hydroxides have good crystal nucleating effects on sodium hydroxide hydrate. The prepared sodium hydroxide hydrate phase change material has the advantages of freeze-thaw cycle stability (>300 times), high phase change enthalpy (180 J / g), high stability, environmental protection and non-toxicity, and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the description of the embodiments or the prior art are briefly introduced below.

[0023] Figure 1 It is the DSC curve diagram of Example 1;

[0024] Figure 2 It is the DSC curve diagram of Example 2;

[0025] Figure 3 It is the DSC curve diagram of Example 3;

[0026] Figure 4 It is the DSC curve diagram of Example 4;

[0027] Figure 5 It is the DSC curve diagram of Example 5;

[0028] Figure 6 This is the DSC curve of Comparative Example 1. DETAILED DESCRIPTION

[0029] The present invention provides a sodium hydroxide hydrate phase change material, comprising the following raw materials in parts by mass: 35 to 50 parts of sodium hydroxide, 0.5 to 3 parts of a crystal nucleating agent or a crystal nucleating agent precursor, and 50 to 65 parts of water;

[0030] Wherein, the crystal nucleating agent comprises at least one of ferrous hydroxide, cobalt hydroxide, manganese hydroxide, chromium hydroxide and strontium hydroxide;

[0031] The crystal nucleating agent precursor includes at least one of ferrous salt, cobalt salt, manganese salt, chromium salt and strontium salt.

[0032] In the present invention, the mass fraction of the sodium hydroxide is preferably 40 to 50 parts, more preferably 46 to 50 parts, and more preferably 50 parts.

[0033] In the present invention, the crystal nucleating agent preferably comprises ferrous hydroxide, cobalt hydroxide, manganese hydroxide, chromium hydroxide or strontium hydroxide, further preferably comprises ferrous hydroxide, cobalt hydroxide or manganese hydroxide, and more preferably is ferrous hydroxide or manganese hydroxide.

[0034] In the present invention, the crystal nucleating agent precursor preferably comprises ferrous salt, cobalt salt, manganese salt, chromium salt or strontium salt, more preferably comprises ferrous salt, cobalt salt or manganese salt, more preferably ferrous salt or manganese salt.

[0035] In the present invention, the ferrous salt preferably comprises ferrous chloride and / or ferrous sulfate, more preferably ferrous chloride or ferrous sulfate, and more preferably ferrous chloride.

[0036] In the present invention, the cobalt salt preferably comprises cobalt chloride and / or cobalt sulfate, more preferably cobalt chloride or cobalt sulfate, and more preferably cobalt chloride.

[0037] In the present invention, the manganese salt preferably comprises manganese chloride and / or manganese sulfate, more preferably manganese chloride or manganese sulfate, and more preferably manganese chloride.

[0038] In the present invention, the chromium salt preferably comprises chromium trichloride.

[0039] In the present invention, the strontium salt preferably comprises strontium chloride.

[0040] In the present invention, the mass fraction of the crystal nucleating agent precursor is preferably 1 to 2 parts, more preferably 1 to 1.5 parts, and more preferably 1.5 parts.

[0041] In the present invention, the mass fraction of water is preferably 50 to 60 parts, more preferably 50 to 54 parts, and even more preferably 50 parts.

[0042] In the present invention, the sodium hydroxide hydrate phase change material preferably further includes a phase change temperature regulator.

[0043] In the present invention, the phase change temperature regulator preferably comprises one or more of sodium chloride, potassium chloride, sodium nitrate and potassium nitrate, further preferably comprises sodium chloride, potassium chloride, sodium nitrate or potassium nitrate, more preferably sodium chloride or potassium chloride.

[0044] In the present invention, the mass fraction of the phase change temperature regulator is preferably 2 to 10 parts, more preferably 6 to 10 parts, and more preferably 6 parts.

[0045] In the present invention, the purpose of adding the phase change temperature regulator is to lower the phase change temperature.

[0046] In the present invention, the sodium hydroxide hydrate phase change material preferably further includes a thickener.

[0047] In the present invention, the thickener is preferably attapulgite.

[0048] In the present invention, the mass fraction of the thickener is preferably 2 to 5 parts, more preferably 3 to 4 parts, and even more preferably 4 parts.

[0049] In the present invention, the purpose of adding the thickener is to ensure that the crystallization nucleating agent generated by the reaction is effectively suspended in the phase change material, thereby improving the storage stability of the phase change material.

[0050] In the present invention, the sodium hydroxide hydrate phase change material preferably further includes a thermally conductive material.

[0051] In the present invention, the thermally conductive material preferably comprises expanded graphite and / or flake graphite, further preferably comprises flake graphite or expanded graphite and flake graphite, and more preferably comprises expanded graphite and flake graphite.

[0052] In the present invention, the mass fraction of the thermal conductive material is preferably 1 to 6 parts, more preferably 5 to 6 parts, and even more preferably 6 parts.

[0053] In the present invention, the purpose of adding the thermal conductive material is to improve the thermal conductivity of the phase change material.

[0054] In the present invention, when the crystal nucleating agent precursor, the phase change temperature regulator, the thickener or the thermal conductive material are preferably multiple types, the ratio between the types is not limited and can be adjusted according to needs.

[0055] The present invention also provides a method for preparing the sodium hydroxide hydrate phase change material, comprising the following steps:

[0056] Mixing sodium hydroxide, a crystal nucleating agent and water to obtain a sodium hydroxide hydrate phase change material;

[0057] Alternatively, the preparation method comprises the following steps:

[0058] Sodium hydroxide, a crystal nucleating agent precursor and water are mixed to carry out double decomposition reaction to obtain a sodium hydroxide hydrate phase change material.

[0059] In the present invention, the method of mixing the sodium hydroxide, the crystal nucleating agent (or the crystal nucleating agent precursor) and water is preferably: mixing the crystal nucleating agent precursor (or the crystal nucleating agent precursor) with water, and then adding sodium hydroxide to mix.

[0060] In the present invention, the temperature of the mixture of the sodium hydroxide, the crystal nucleating agent and the water and the double decomposition reaction is independently preferably 10 to 60°C, more preferably 20 to 40°C, and more preferably 25°C; the rotation speed is independently preferably 10 to 100 rpm, more preferably 20 to 80 rpm, and more preferably 60 rpm; the time is independently preferably 10 to 30 min, more preferably 15 to 25 min, and more preferably 20 min.

[0061] In the present invention, the method of adding the phase change temperature regulator, the thickener or the thermal conductive material is preferably as follows: at 10 to 60° C. and 10 to 100 rpm, water is mixed with a crystallization nucleating agent (crystallization nucleating agent precursor) and a phase change temperature regulator, sodium hydroxide is added after uniform dispersion, and after complete dissolution, a thickener and a thermal conductive material are added, and the mixture is cooled to room temperature.

[0062] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0063] Example 1

[0064] The present embodiment provides a sodium hydroxide hydrate phase change material, comprising the following raw materials in parts by mass: 40 parts of sodium hydroxide, 60 parts of deionized water, 1 part of ferrous hydroxide, a crystallization nucleating agent, 4 parts of attapulgite, a thickener, and 1 part of expanded graphite, a thermal conductive material.

[0065] This embodiment also provides a method for preparing a sodium hydroxide hydrate phase change material, comprising the following steps:

[0066] At 10°C and 100 rpm, a crystal nucleating agent was added to deionized water and mixed evenly, and then sodium hydroxide was added thereto and stirred for 20 minutes until it was completely dissolved, and then a thickener and a thermal conductive material were added and stirred evenly and cooled to room temperature to obtain a sodium hydroxide hydrate phase change material.

[0067] Example 2

[0068] The present embodiment provides a sodium hydroxide hydrate phase change material, comprising the following raw materials in parts by mass: 46 parts of sodium hydroxide, 54 parts of deionized water, 2 parts of cobalt hydroxide, a crystal nucleating agent, 2 parts of attapulgite, a thickener, and 6 parts of a thermal conductive material (expanded graphite: flake graphite = 1:5).

[0069] This embodiment also provides a method for preparing a sodium hydroxide hydrate phase change material, comprising the following steps:

[0070] At 46°C and 60rpm, a crystal nucleating agent was added to deionized water and mixed evenly, and then sodium hydroxide was added thereto and stirred for 10 minutes until it was completely dissolved. Then, a thickener and a thermal conductive material were added and stirred evenly and cooled to room temperature to obtain a sodium hydroxide hydrate phase change material.

[0071] Example 3

[0072] The present embodiment provides a sodium hydroxide hydrate phase change material, comprising the following raw materials in parts by weight: 50 parts of sodium hydroxide, 50 parts of deionized water, 1.5 parts of a crystal nucleating agent manganese hydroxide, 5 parts of a thickening agent attapulgite, and 2 parts of a thermal conductive material expanded graphite.

[0073] This embodiment also provides a method for preparing a sodium hydroxide hydrate phase change material, comprising the following steps:

[0074] At 60° C. and 10 rpm, a crystal nucleating agent was added to deionized water and mixed evenly, and then sodium hydroxide was added thereto and stirred for 30 minutes until it was completely dissolved. Then, a thickener and a thermal conductive material were added and stirred evenly and cooled to room temperature to obtain a sodium hydroxide hydrate phase change material.

[0075] Example 4

[0076] The present embodiment provides a sodium hydroxide hydrate phase change material, comprising the following raw materials in parts by mass: 46 parts of sodium hydroxide, 54 parts of deionized water, 2 parts of chromium trichloride as a crystal nucleating agent precursor, 6 parts of potassium chloride as a phase change temperature regulator, 3 parts of attapulgite as a thickener, and 5 parts of flake graphite as a thermal conductive material.

[0077] This embodiment also provides a method for preparing a sodium hydroxide hydrate phase change material, comprising the following steps:

[0078] At 25°C and 40rpm, a crystal nucleating agent precursor and a phase change temperature regulator were added to deionized water and mixed evenly, and then sodium hydroxide was added thereto to react for 15 minutes until it was completely dissolved, and then a thickener and a thermal conductive material were added, stirred evenly, and cooled to room temperature to obtain a sodium hydroxide hydrate phase change material.

[0079] Example 5

[0080] The present embodiment provides a sodium hydroxide hydrate phase change material, comprising the following raw materials in parts by mass: 50 parts of sodium hydroxide, 50 parts of deionized water, 1.5 parts of strontium chloride, a crystal nucleating agent precursor, 10 parts of sodium chloride, a phase change temperature regulator, 4 parts of attapulgite, and 5 parts of a thermal conductive material (expanded graphite: flake graphite = 2:3).

[0081] This embodiment also provides a method for preparing a sodium hydroxide hydrate phase change material, comprising the following steps:

[0082] At 50°C and 80rpm, a crystal nucleating agent precursor and a phase change temperature regulator were added to deionized water and mixed evenly, and then sodium hydroxide was added thereto to react for 25 minutes until it was completely dissolved, and then a thickener and a thermal conductive material were added, stirred evenly, and cooled to room temperature to obtain a sodium hydroxide hydrate phase change material.

[0083] Comparative Example 1

[0084] This comparative example provides a sodium hydroxide hydrate phase change material, which comprises the following raw materials in parts by weight: 40 parts of sodium hydroxide and 60 parts of deionized water.

[0085] This comparative example also provides a method for preparing a sodium hydroxide hydrate phase change material, comprising the following steps:

[0086] The sodium hydroxide and deionized water are evenly mixed to obtain a sodium hydroxide hydrate phase change material.

[0087] The formulations of Examples 1 to 5 and Comparative Example 1 are shown in Table 1. The phase change temperature and phase change enthalpy of the sodium hydroxide hydrate phase change materials obtained in Examples 1 to 5 and Comparative Example 1 were tested by differential scanning calorimetry. The results are as follows: Figures 1 to 6, as shown in Table 2. The thermal conductivity of the sodium hydroxide hydrate phase change materials obtained in Examples 1 to 5 and Comparative Example 1 was tested by using the Hot Disk method / transient flat plate heat source method. The results are shown in Table 2.

[0088] Table 1. Formulas of Examples 1 to 5 and Comparative Example 1

[0089] raw material Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Sodium hydroxide 40 46 50 46 50 40 water 60 54 50 54 50 60 Ferrous hydroxide 1 —— —— —— —— —— Cobalt hydroxide —— 2 —— —— —— —— Manganese hydroxide —— —— 1.5 —— —— —— Chromium trichloride —— —— —— 2 —— —— Strontium chloride —— —— —— —— 1.5 —— Potassium chloride —— —— —— 6 —— —— Sodium chloride —— —— —— —— 10 —— Attapulgite 4 2 5 3 4 —— Expanded Graphite 1 1 2 —— 2 —— Flake Graphite —— 5 —— 5 3 ——

[0090] Table 2. Test results of sodium hydroxide hydrate phase change materials obtained in Examples 1 to 5 and Comparative Example 1

[0091]

[0092] The results of Table 2 show that different hydrates can be formed with the change of sodium hydroxide content, and have different phase change temperatures and phase change enthalpies. Since comparative example 1 does not contain graphite, the thermal conductivity is only 0.54W / (Km), while the thermal conductivity of embodiment 5 can reach 2.53W / (Km) after adding 2 parts of expanded graphite and 3 parts of flake graphite. The thermal conductivity test results of embodiments 1 to 5 show that expanded graphite can significantly improve the thermal conductivity of phase change materials, and flake graphite can form a synergistic effect with expanded graphite. Freeze-thaw cycle tests were performed on embodiments 1 to 5 and comparative example 1 in the range of 4 to 20°C. The results show that comparative example 1 cannot crystallize after 60 freeze-thaw cycles at 4 to 20°C due to the absence of crystallization nucleating agent and thickener attapulgite. However, embodiments 1 to 5 can still crystallize after 300 freeze-thaw cycles at 4 to 20°C due to the addition of crystallization nucleating agent and attapulgite.

[0093] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A sodium hydroxide hydrate phase change material, characterized in that: The method comprises the following raw materials in parts by weight: 35 to 50 parts of sodium hydroxide, 0.5 to 3 parts of a crystal nucleating agent or a crystal nucleating agent precursor, and 50 to 65 parts of water; Wherein, the crystal nucleating agent comprises at least one of ferrous hydroxide, cobalt hydroxide, manganese hydroxide, chromium hydroxide and strontium hydroxide; The crystal nucleating agent precursor includes at least one of ferrous salt, cobalt salt, manganese salt, chromium salt and strontium salt.

2. The sodium hydroxide hydrate phase change material according to claim 1, wherein The ferrous salt comprises ferrous chloride and / or ferrous sulfate, the cobalt salt comprises cobalt chloride and / or cobalt sulfate, the manganese salt comprises manganese chloride and / or manganese sulfate, the chromium salt comprises chromium trichloride, and the strontium salt comprises strontium chloride.

3. The sodium hydroxide hydrate phase change material according to claim 1, wherein The sodium hydroxide hydrate phase change material also includes 2 to 10 parts of a phase change temperature regulator.

4. The sodium hydroxide hydrate phase change material according to claim 3, wherein The phase change temperature regulator includes one or more of sodium chloride, potassium chloride, sodium nitrate and potassium nitrate.

5. The sodium hydroxide hydrate phase change material according to claim 1 or 3, characterized in that: The sodium hydroxide hydrate phase change material also includes 2 to 5 parts of a thickener.

6. The sodium hydroxide hydrate phase change material according to claim 5, wherein The thickener is attapulgite.

7. The sodium hydroxide hydrate phase change material according to claim 5, wherein The sodium hydroxide hydrate phase change material also includes 1 to 6 parts of heat conductive material.

8. The sodium hydroxide hydrate phase change material according to claim 7, wherein The thermally conductive material comprises expanded graphite and / or flake graphite.

9. The method for preparing a sodium hydroxide hydrate phase change material according to any one of claims 1 to 8, characterized in that: The following steps are involved: Mixing sodium hydroxide, a crystal nucleating agent and water to obtain a sodium hydroxide hydrate phase change material; Alternatively, the preparation method comprises the following steps: Sodium hydroxide, a crystal nucleating agent precursor and water are mixed to carry out double decomposition reaction to obtain a sodium hydroxide hydrate phase change material.

10. The preparation method according to claim 9, characterized in that: The temperature of the mixture of the sodium hydroxide, the crystal nucleating agent and the water and the double decomposition reaction is independently 10-60° C., the rotation speed is independently 10-100 rpm, and the time is independently 10-30 min.

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