Ceramic-based multi-component inorganic salt composite phase change heat storage material and preparation method thereof

Abstract

The application discloses a ceramic-based multi-component inorganic salt composite phase change heat storage material and belongs to the field of phase change materials. The ceramic-based multi-component inorganic salt composite phase change heat storage material comprises the following components in percentage by mass: 10-15% of lithium fluoride; 60-65% of lithium hydroxide; 25-30% of sodium chloride; the total mass of the inorganic salts is 100%; and the following components are additionally added according to the total mass of the inorganic salts: 20-30% of a ceramic carrier and 0.5-1% of a binder. The lithium fluoride, lithium hydroxide and sodium chloride composite inorganic salt system is used for the first time, the phase change temperature can be regulated by controlling the component proportion, the phase change latent heat is high, the flow of the inorganic salt undergoing phase change can be reduced by regulating the ceramic carrier proportion, the shape stability can be maintained during the phase change process, direct contact between the inorganic salt and the container and corrosion can be reduced, and the stability of the composite phase change material can be maintained. The application further discloses a preparation method of the ceramic-based multi-component inorganic salt composite phase change heat storage material.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of composite phase change heat storage materials and preparation method thereof, specifically a kind of ceramic-based multi-inorganic salt composite phase change heat storage material and preparation method thereof, belong to the field of phase change materials. BACKGROUND

[0002] Inorganic salt phase change material is the phase change heat storage material with application prospect, its heat storage density is large use temperature range is wide, stability is good, cost is low.Preparation high heat storage performance phase change material becomes the emphasis of research.However, existing inorganic salt is easy to cause corrosion to container and equipment in phase change process, greatly improve the cost of heat storage system, limit inorganic salt in the large-scale application in heat storage field. SUMMARY

[0003] The technical problem to be solved by the present application is to overcome the defects of the prior art, provide a kind of inorganic salt that can reduce the flow of phase change, and keep shape stable in phase change process, thereby reducing the direct contact and corrosion between inorganic salt and container, controllable phase change temperature range is wide, phase change latent heat is high and thermal stability is high Ceramic-based multi-inorganic salt composite phase change heat storage material and preparation method thereof.

[0004] To solve the above technical problems, the ceramic-based multi-inorganic salt composite phase change heat storage material provided by the present application comprises the following components by mass percentage:

[0005] 10-15% of lithium fluoride;

[0006] 60-65% of lithium hydroxide;

[0007] 25-30% of sodium chloride;

[0008] The total mass of the above inorganic salt is 100%;

[0009] In addition, the following components are added according to the total mass of the above inorganic salt:

[0010] 20-30% of ceramic carrier,

[0011] 0.5-1% of binder.

[0012] In the present application, the ceramic carrier is diatomite or magnesium oxide.

[0013] In the present application, the binder is polyvinyl alcohol.

[0014] The present application also provides a preparation method of ceramic-based multi-inorganic salt composite phase change heat storage material, characterized by comprising the following steps:

[0015] Step one: lithium fluoride, lithium hydroxide and sodium chloride are mixed according to the formula amount to form an inorganic salt system;

[0016] Step two: the inorganic salt system of step one is mixed by grinding to obtain mixture A;

[0017] Step three: the mixture A obtained in step two is added with the formula amount of ceramic carrier and binder for ball milling to obtain mixture B;

[0018] Step four: the mixture B is pressed into a cylindrical sample C;

[0019] Step five: the cylindrical sample C pressed in step four is sintered at high temperature, and the ceramic-based multi-element inorganic salt composite phase change heat storage material is obtained after cooling.

[0020] In the present application, the grinding time of the composite salt system in step two is 40-60 min, and the average particle size of the mixture A is 150-200 microns.

[0021] In the present application, the ball milling speed in step three is 200-300 r / min, and the ball milling time is 50-60 min.

[0022] In the present application, the mixture B in step four is poured into a mold and pressed into shape by a powder tablet press; the pressing rate of the formed shape is 2-4 MPa / min, the pressure is pressed to 20-40 MPa, and the pressure holding time is 5-10 min.

[0023] In the present application, the cylindrical sample C in step five is sintered at high temperature at a heating rate of 5-10 ℃ / min, the sintering temperature is 400-450 ℃, and the sintering time is 1-3 h.

[0024] The present application has the following advantages: (1) the composite inorganic salt system composed of lithium fluoride, lithium hydroxide and sodium chloride is used for the first time, the phase change temperature can be adjusted by controlling the component ratio, and the phase change latent heat is high; (2) by adjusting the proportion of the ceramic carrier, the flow of the inorganic salt during phase change can be reduced, and the shape stability during phase change can be maintained, thereby reducing the direct contact and corrosion between the inorganic salt and the container, and maintaining the stability of the composite phase change material; (3) the preparation process of the present application is fast, the operation is simple, the preparation cost is low, and it can be used for large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0025] The above and / or other aspects of the present application will become apparent from the following detailed description of the application taken in conjunction with the accompanying drawings.

[0026] Figure 1 is the DSC curve of the composite phase change material prepared in Example 1;

[0027] Figure 2 is the DSC curve of the composite phase change material prepared in Example 2;

[0028] Figure 3 DSC curve of the composite phase change material prepared in Example 3 is shown in Figure 3;

[0029] Figure 4 DSC curve of the composite phase change material prepared in Example 4 is shown in Figure 4;

[0030] Figure 5 DSC curve of the composite phase change material prepared in Comparative Example 1 is shown in Figure 5. DETAILED DESCRIPTION

[0031] So that the objects, technical solutions and advantages of the embodiments of the present application are more apparent, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without making creative efforts are within the scope of protection of the present application.

[0033] Some embodiments of the present application will be described in detail below with reference to the drawings. The following embodiments and features in the embodiments can be combined with each other without conflict.

[0034] The technical principle of the present application is that: in view of the fact that lithium fluoride, lithium hydroxide and sodium chloride have high latent heat of fusion and suitable melting points, meeting the requirements of low-temperature phase change materials, by regulating the appropriate proportion, regular eutectic can be formed by simultaneous melting and re-solidification, realizing eutectic. First, the phase diagram of the lithium fluoride and sodium chloride binary system is analyzed and found, the eutectic point of the binary system is determined, and the ratio of the system is determined; then the binary system is considered as a single component and compounded with lithium hydroxide to determine the ratio to achieve eutectic, thereby obtaining the final ratio of the three components. The addition of the ceramic carrier ensures that the composite material can maintain shape stability while maximizing the latent heat of fusion. Polyvinyl alcohol is selected as the binder, which has strong adhesion and can ensure that the ceramic carrier is quickly formed to fix the phase change material.

[0035] Example 1

[0036] Accurately weighed 3.0 g of dried lithium fluoride, 18.6 g of lithium hydroxide and 8.4 g of sodium chloride were manually mixed, and then 9 g of diatomite and 0.3 g of polyvinyl alcohol solution were added. The above mixture was put into a mortar and ground for 60 min to obtain mixture A, and the average particle size of mixture A was 200 microns; mixture A was loaded into a ball mill tank and put into a ball mill, and was ball milled at 300 r / min for 60 min to obtain mixture B; after mixing uniformly, mixture B was poured into a mold, and was placed on a press machine at a pressing rate of 3 MPa / min, and was pressed into a cylindrical sample with a diameter of 15 mm and a thickness of 3 mm at 40 MPa for 5 min, and then the pressed sample was put into a resistance furnace and heated to 400℃ at a heating rate of 5℃ / min, and was sintered for 1 h to obtain a ceramic-based multi-component inorganic salt composite phase change heat storage material, and the DSC result thereof is shown in Figure 1 The initial phase change temperature (T) is 379.01℃, and the phase change latent heat (ΔH) is 370.71 J / g.

[0037] Example 2

[0038] Accurately weighed 3.6 g of dried lithium fluoride, 18.9 g of lithium hydroxide and 7.5 g of sodium chloride were manually mixed, and then 9 g of diatomite and 0.3 g of polyvinyl alcohol solution were added. The above mixture was put into a mortar and ground for 60 min to obtain mixture A, and the average particle size of mixture A was 200 microns; mixture A was loaded into a ball mill tank and put into a ball mill, and was ball milled at 300 r / min for 60 min to obtain mixture B; after mixing uniformly, mixture B was poured into a mold, and was placed on a press machine at a pressing rate of 3 MPa / min, and was pressed into a cylindrical sample with a diameter of 15 mm and a thickness of 3 mm at 40 MPa for 5 min, and then the pressed sample was put into a resistance furnace and heated to 400℃ at a heating rate of 5℃ / min, and was sintered for 1 h to obtain a ceramic-based multi-component inorganic salt composite phase change heat storage material, and the DSC result thereof is shown in Figure 1 The initial phase change temperature (T) is 377.14℃, and the phase change latent heat (ΔH) is 374.23 J / g.

[0039] Example 3

[0040] After 3.6 g of lithium fluoride, 18.6 g of lithium hydroxide and 7.8 g of sodium chloride after drying were accurately weighed and mixed manually, 6 g of magnesium oxide and 0.3 g of polyvinyl alcohol solution were added thereto. The above mixture was put into a mortar and ground for 60 min to obtain a mixture A, and the average particle size of the mixture A was 150 microns; the mixture A was loaded into a ball mill tank and put into a ball mill, and was ball milled at 300 rpm for 60 min to obtain a mixture B; after mixing uniformly, the mixture B was poured into a mold, and was placed on a press to be pressed at a pressing rate of 4 MPa / min, and was kept at 40 MPa for 5 min to be pressed into a cylindrical sample with a diameter of 15 mm and a thickness of 3 mm, and then the pressed sample was put into a resistance furnace and was heated to 400℃ at a heating rate of 5℃ / min, and was sintered for 1 h to obtain a ceramic-based multi-component inorganic salt composite phase change heat storage material, and the DSC result thereof is shown in Figure 2 , the initial phase change temperature (T) was 378.36℃, and the phase change latent heat (ΔH) was 380.58 J / g.

[0041] Example 4

[0042] After 4.5 g of lithium fluoride, 18.0 g of lithium hydroxide and 7.5 g of sodium chloride after drying were accurately weighed and mixed manually, 6 g of magnesium oxide and 0.3 g of polyvinyl alcohol solution were added thereto. The above mixture was put into a mortar and ground for 60 min to obtain a mixture A, and the average particle size of the mixture A was 150 microns; the mixture A was loaded into a ball mill tank and put into a ball mill, and was ball milled at 300 rpm for 60 min to obtain a mixture B; after mixing uniformly, the mixture B was poured into a mold, and was placed on a press to be pressed at a pressing rate of 4 MPa / min, and was kept at 40 MPa for 5 min to be pressed into a cylindrical sample with a diameter of 15 mm and a thickness of 3 mm, and then the pressed sample was put into a resistance furnace and was heated to 400℃ at a heating rate of 5℃ / min, and was sintered for 1 h to obtain a ceramic-based multi-component inorganic salt composite phase change heat storage material, and the DSC result thereof is shown in Figure 2 , the initial phase change temperature (T) was 383.42℃, and the phase change latent heat (ΔH) was 379.05 J / g.

[0043] Comparative Example 1

[0044] After 2.7 g of lithium fluoride, 19.6 g of lithium hydroxide and 7.7 g of sodium chloride after drying are weighed accurately and mixed manually, 6 g of magnesium oxide and 0.3 g of polyvinyl alcohol solution are added. The above mixture is put into a mortar and ground for 60 min to obtain mixture A, the average particle size of mixture A is 200 microns, mixture A is loaded into a ball mill tank and put into a ball mill, and the mixture B is obtained by ball milling at 300 r / min for 60 min; after mixing uniformly, the mixture B is poured into a mold, placed on a press machine, and pressed into a cylindrical sample with a diameter of 15 mm and a thickness of 3 mm at a pressing rate of 4 MPa / min and a pressure of 40 MPa for 5 min, and then the pressed sample is placed in a resistance furnace and heated to 400℃ at a heating rate of 5℃ / min, and sintered for 1h to obtain a ceramic-based multi-component inorganic salt composite phase change heat storage material, and the DSC result thereof is shown in Figure 3 The initial phase change temperature (T) is 389.29℃, and the phase change latent heat (ΔH) is 241.67J / g.

[0045] Comparing the comparative example 1 with the examples 1 and 2, it can be found that the phase change temperature of the composite phase change material prepared by using the lithium fluoride, lithium hydroxide and sodium chloride composite salt system outside the above ratio range is higher, the phase change latent heat is obviously lower, and the system has a peak phenomenon, and the stability is reduced. The system of lithium fluoride, lithium hydroxide and sodium chloride within the ratio range can achieve the purpose of high latent heat, and outside the ratio range, the purpose of the present application cannot be achieved.

[0046] The present application provides a kind of ceramic-based multi-component inorganic salt composite phase change material and its preparation method, and the thought and method of method and approach for realizing the technical scheme are many, above-mentioned only is preferred embodiment of the present application, it should be pointed out, for the ordinary skilled in the art, without departing from the principles of the present application, can make a number of improvements and refinements, these improvements and refinements also should be considered as the protection scope of the present application. The components not explicitly described in the embodiment can be realized by existing technology.

Claims

1. A ceramic-based multi-element inorganic salt composite phase change thermal storage material, characterized in that, Components include the following percentage by weight: 10-15% lithium fluoride; 60-65% lithium hydroxide; 25-30% sodium chloride; The total mass of the above inorganic salts is 100%; In addition, the following components are added based on the total mass of the above inorganic salts: 20-30% ceramic carrier, wherein the ceramic carrier is diatomaceous earth or magnesium oxide; 0.5% to 1% of an adhesive, wherein the adhesive is polyvinyl alcohol.

2. The preparation method of the ceramic-based multi-element inorganic salt composite phase change thermal storage material according to claim 1, characterized in that, Includes the following steps: Step 1: Mix lithium fluoride, lithium hydroxide, and sodium chloride according to the formula to form an inorganic salt system; Step 2: Thoroughly grind and mix the inorganic salt system from Step 1 to obtain Mixture A; Step 3: Add the prescribed amounts of ceramic carrier and binder to mixture A obtained in Step 2 and ball mill to obtain mixture B; Step 4: Press mixture B into cylindrical sample C; Step 5: The cylindrical sample C, which was pressed and formed in Step 4, is sintered at high temperature and cooled to obtain a ceramic-based multi-element inorganic salt composite phase change thermal storage material.

3. The preparation method of the ceramic-based multi-element inorganic salt composite phase change thermal storage material according to claim 2, characterized in that: The grinding time of the composite salt system in step two is 40 to 60 minutes, and the average particle size of mixture A is 150 to 200 micrometers.

4. The preparation method of the ceramic-based multi-element inorganic salt composite phase change thermal storage material according to claim 2, characterized in that: In step three, the ball milling speed is 200-300 r / min, and the ball milling time is 50-60 min.

5. The preparation method of the ceramic-based multi-element inorganic salt composite phase change thermal storage material according to claim 2, characterized in that: In step four, mixture B is poured into a mold and pressed into shape using a powder tablet press. The pressing rate for the molding is 2-4 MPa / min, the pressure is increased to 20-40 MPa, and the holding time is 5-10 min.

6. The preparation method of the ceramic-based multi-element inorganic salt composite phase change thermal storage material according to claim 2, characterized in that: In step five, the heating rate of the cylindrical sample C during high-temperature sintering is 5–10 °C / min, the sintering temperature is 400–450 °C, and the sintering time is 1–3 h.

Images