Organic base stable supercooled sugar alcohol long-term heat storage composite phase change material and preparation method thereof

Abstract

The invention relates to the technical field of phase change heat storage material preparation and heat energy storage, in particular to an organic base stable supercooled sugar alcohol long-term heat storage composite phase change material and a preparation method thereof. According to the composite phase change material, one or more of organic alkali including but not limited to a polyamine compound (such as diethylenetriamine), a nitrogen-containing heterocyclic compound (such as 1, 8-diazabicyclo [5.4. 0] undec-7-ene, DBU for short) and organic alkali metal compounds (such as potassium tert-butoxide and sodium tert-butoxide) are used as additives, and the organic alkali metal compounds are added into the composite phase change material. Four sugar alcohols including erythritol, xylitol, mannitol and inositol are used as main energy storage agents. The novel phase change heat storage material which is high in enthalpy value and high in stability and can be used for cross-seasonal long-term heat storage is prepared by selecting raw materials with low cost and using a simple and rapid mechanical melt blending preparation method. In addition, the organic alkali-stabilized supercooled sugar alcohol-based long-term heat storage composite phase change material also has the advantage of being capable of keeping a supercooled state at room temperature, and the application range of the phase change heat storage material is further expanded. The method has great application potential in the fields of waste heat recovery, solar heat utilization and the like.

Description

Technical Field

[0001] The present invention belongs to the field of cross-season composite phase change heat storage materials, and specifically relates to an organic base stabilized supercooled sugar alcohol long-term heat storage composite phase change material and a preparation method thereof. Technical Background

[0002] At present, the widely used green and clean energy such as solar energy and wind energy are highly volatile due to the influence of the changing seasons and weather changes. Developing efficient thermal energy storage technology is an important means to solve the above problems and expand the scope of solar energy application.

[0003] Phase change heat storage materials have high heat storage density and small heat storage range, which can solve the uneven distribution of energy supply and demand in time and space and improve energy utilization. However, phase change materials have large supercooling, severe heat dissipation and instability during long-term storage across seasons.

[0004] In addition to the problem of poor stability, sugar alcohol phase change materials also have the advantages of large supercooling, suitable phase change temperature and high latent heat enthalpy value. Therefore, as a cross-seasonal heat storage material, it shows good adaptability. Solving the stability problem of sugar alcohol phase change materials in long-term heat storage is the key to realizing cross-seasonal heat storage applications. Summary of the invention

[0005] In order to solve the problem of poor stability of sugar alcohol phase change materials during long-term storage, the present invention designs a long-term sugar alcohol-based phase change heat storage composite material with high energy density and stable supercooled state, introduces an organic base as a sugar alcohol stabilizer to achieve long-term energy storage in a stable supercooled state, and provides an organic base-stabilized supercooled state sugar alcohol-based long-term heat storage composite material and a preparation method thereof.

[0006] In order to achieve the above technical objectives, the technical solution adopted by the present invention is: An organic base stabilized supercooled sugar alcohol-based long-term heat storage composite material, the mass ratio of each component is: 1-20 parts by mass of organic base, 80-99 parts by mass of sugar alcohol, wherein sugar alcohol is a commonly used phase change energy storage material, has a large supercooling degree and a large phase change enthalpy value, the organic base stabilizer can form new hydrogen bonds with the sugar alcohol molecules, increase the viscosity of the sugar alcohol, and hinder the movement and crystallization of the sugar alcohol molecules, thereby preparing a stable supercooled heat storage phase change material, which can stabilize the sugar alcohol in the supercooled state for more than one month at room temperature, thereby achieving long-term cross-seasonal heat storage.

[0007] The sugar alcohol can be one or more of erythritol, xylitol, mannitol and inositol.

[0008] Furthermore, the organic base includes, but is not limited to: one or more of polyamine compounds (such as diethylenetriamine), nitrogen-containing heterocyclic compounds (such as 1,8-diazabicyclo[5.4.0]undec-7-ene, abbreviated as DBU) and organic alkaline metal compounds (such as potassium tert-butoxide, sodium tert-butoxide).

[0009] Furthermore, the organic base stabilized supercooled sugar alcohol long-term heat storage composite phase change material and the preparation method thereof include the following experimental steps:

[0010] (1) heating a certain amount of sugar alcohol to a temperature higher than the melting point of the sugar alcohol so that the sugar alcohol is completely melted;

[0011] (2) Add the organic base into the melted sugar alcohol solution in proportion, continue heating and stirring to mix evenly.

[0012] (3) placing the mixed solution in a low temperature environment and allowing it to stand until it presents a stable deep supercooled state; thereby obtaining a stable supercooled sugar alcohol-based phase change material.

[0013] Furthermore, in the specific step (1), the mass fractions of the organic base and the sugar alcohol are in the range of 1-20% and 80-99% respectively.

[0014] Furthermore, the heating temperature in step (2) should be 20-30° C. higher than the melting point of the sugar alcohol. The stirring rate is 400-600 rpm.

[0015] Furthermore, the low temperature environment temperature of the specific step (3) should be 90-120° C. lower than the heating temperature.

[0016] The principle of the present invention is: supercooled long-term heat storage material refers to a special phase change material with stable supercooling behavior. In the cooling process after melting, the supercooled phase change material can maintain a deeply supercooled non-crystalline state without external force, and begins to crystallize and release stored heat energy after external stimulation. By prolonging the non-crystalline state of the phase change material and preparing a stable supercooled phase change material at room temperature, the energy storage efficiency of the phase change material in long-term heat storage can be effectively improved. The organic base composite phase change material of the present invention has high energy storage efficiency, long aging time, and good stability, and can play a role in the process of long-term heat storage.

[0017] Sugar alcohol phase change materials have a large number of hydrogen bonds, which affect the melting and crystallization process. By changing the number of hydrogen bonds, the phase change behavior of sugar alcohol can be selectively regulated, thereby preparing a stable supercooled sugar alcohol long-term heat storage material. By introducing organic bases to form new intermolecular hydrogen bonds with sugar alcohols, the movement of sugar alcohol molecules is slowed down, the viscosity is increased, and a long-term stable supercooled sugar alcohol heat storage composite material at room temperature is prepared.

[0018] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

[0019] (1) A simple and efficient preparation method is provided for supercooled sugar alcohol-based long-term heat storage composite phase change material, which provides a new solution and energy storage material for cross-seasonal heat storage. The material can maintain a stable supercooled state for more than three months at room temperature, thereby maximizing the long-term and efficient storage of the absorbed heat energy in the phase change material.

[0020] (2) The present invention improves the viscosity of the material by compounding the organic base with the sugar alcohol, increases the crystallization energy barrier of the sugar alcohol, and hinders the crystallization of the sugar alcohol, thereby preparing a stable supercooled sugar alcohol-based composite phase change material. The present invention has simple process, low cost, good stability, low energy consumption, and good product yield effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a photo of the crystallinity test experiment of pure erythritol;

[0022] Figure 2 This is a photo of the supercooling stability experiment of erythritol composite phase change material;

[0023] Figure 3 DSC was used to test the phase transition behavior of supercooled erythritol composites;

[0024] Figure 4 The enthalpy changes of loading different contents of diethylenetriamine for erythritol; DETAILED DESCRIPTION

[0025] Example 1

[0026] A method for preparing an organic base-stabilized supercooled sugar alcohol-based long-term heat storage composite material comprises the following steps:

[0027] (1) Preparation of mixture: Weigh 14.25 g erythritol and 0.75 g diethylenetriamine, and mix well.

[0028] (2) The mixture was heated and stirred in an oil bath at 150° C. for 2 hours to prepare a stable supercooled sugar alcohol-based composite phase change material.

[0029] Example 2

[0030] A method for preparing an organic base-stabilized supercooled sugar alcohol-based long-term heat storage composite material comprises the following steps:

[0031] (1) Preparation of mixture: weigh 13.5 g erythritol and 1.5 g diethylenetriamine, and mix well;

[0032] (2) The mixture was heated and stirred in an oil bath at 150° C. for 2 hours to prepare a stable supercooled sugar alcohol-based composite phase change material.

[0033] Example 3

[0034] A method for preparing an organic base-stabilized supercooled sugar alcohol-based long-term heat storage composite material comprises the following steps:

[0035] (1) Preparation of mixture: weigh 12.75 g erythritol and 2.25 g diethylenetriamine, and mix them evenly;

[0036] (2) The mixture was heated and stirred in an oil bath at 150° C. for 2 hours to prepare a stable supercooled sugar alcohol-based composite phase change material.

[0037] Example 4

[0038] A method for preparing an organic base-stabilized supercooled sugar alcohol-based long-term heat storage composite material comprises the following steps:

[0039] (1) Preparation of a mixture: Weigh 13.5 g of erythritol and 1.5 g of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and mix them evenly;

[0040] (2) The mixture was heated and stirred in an oil bath at 150° C. for 2 hours to prepare a stable supercooled sugar alcohol-based composite phase change material.

[0041] Example 5

[0042] A method for preparing an organic base-stabilized supercooled sugar alcohol-based long-term heat storage composite material comprises the following steps:

[0043] (1) Preparation of mixture: weigh 13.5 g erythritol and 1.5 g potassium tert-butoxide and mix well;

[0044] (2) The mixture was heated and stirred in an oil bath at 150° C. for 2 hours to prepare a stable supercooled sugar alcohol-based composite phase change material.

[0045] The phase change properties of the organic base-stabilized supercooled sugar alcohol-based long-term heat storage composite materials prepared in Examples 1 to 5 were tested in a N2 atmosphere at a heating and cooling rate of 10°C / min in a temperature range of -30 to 150°C. The obtained DSC curves and thermophysical property results are shown in Figures 1 to 5. Figure 3 Shown and listed in Table 1.

[0046] Table 1 Thermophysical properties of organic base-stabilized supercooled sugar alcohol-based long-term heat storage composite materials

[0048] As shown in Table 1, the phase change enthalpy of the organic base-stabilized supercooled sugar alcohol-based long-term heat storage composite material prepared by the present invention is determined by the amount of sugar alcohol phase change material loaded in the setting system. The higher the mass fraction of the sugar alcohol phase change material, the higher the phase change enthalpy.

[0049] The accompanying drawings supplement the implementation results of the embodiment.

[0050] Figure 1 This shows that erythritol itself is unstable when supercooled. It will spontaneously crystallize during the cooling process and cannot store heat stably for a long time at room temperature.

[0051] Figure 2 It is described that after 180 days of heat storage, the erythritol composite material prepared according to the example is still in a deeply supercooled state and has the ability to store heat across seasons for a long time.

[0052] Figure 3 It is illustrated that the erythritol composite material prepared according to the example can still release the stored heat energy after being placed for a long time.

[0053] Figure 4 The DSC curves of the effects of different contents of diethylenetriamine on the solid-liquid phase transition behavior of erythritol composites were described, and it was found that the enthalpy of the composite material gradually decreased with the increase of diethylenetriamine content.

[0054] Although the specific implementation of the present invention is described in detail in conjunction with the drawings, it should not be understood as limiting the scope of protection of this patent. Within the scope described in the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. An organic base-stabilized supercooled sugar alcohol-based long-term heat storage composite phase change material and a preparation method thereof, characterized in that: Including sugar alcohols and organic base stabilizers.

2. The organic base-stabilized supercooled sugar alcohol-based long-term heat storage composite phase change material and its preparation method according to claim 1, characterized in that: The sugar alcohol is one or more of erythritol, xylitol, mannitol and inositol.

3. The organic base-stabilized supercooled sugar alcohol long-term heat storage composite phase change material and its preparation method according to claim 1, characterized in that: The additive is an organic base, which includes but is not limited to: one or more of polyamine compounds (such as diethylenetriamine), nitrogen-containing heterocyclic compounds (such as 1,8-diazabicyclo[5.4.0]undec-7-ene, abbreviated as DBU) and organic alkaline metal compounds (such as potassium tert-butoxide, sodium tert-butoxide).

4. An organic base-stabilized supercooled sugar alcohol long-term heat storage composite phase change material and a preparation method thereof according to any one of claims 1 to 3, characterized in that: The steps include: Step (1), heating a certain amount of sugar alcohol at a temperature higher than the melting point of the sugar alcohol until it melts; Step (2), adding an organic base to the melted sugar alcohol solution in proportion, continuously heating and stirring evenly; Step (3), placing the mixed solution in a low temperature environment and letting it stand until it presents a stable deep supercooled state; thereby obtaining a stable supercooled sugar alcohol-based phase change material.

5. The organic base-stabilized supercooled sugar alcohol long-term heat storage composite phase change material and its preparation method according to claim 4, characterized in that: In the step (1), the mass fraction of the organic base is in the range of 1 to 20%, and the mass fraction of the sugar alcohol is in the range of 80 to 99%.

6. The organic base-stabilized supercooled sugar alcohol long-term heat storage composite phase change material and preparation method thereof according to claim 4, characterized in that: The heating temperature of step (2) should be 20-30° C. higher than the melting point of the sugar alcohol, and the stirring speed should be 400-600 rpm.

7. The organic base-stabilized supercooled sugar alcohol long-term heat storage composite phase change material and preparation method thereof according to claim 4, characterized in that: The low temperature environment of step (3) should be 90-120° C. lower than the heating temperature.

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