Novel low-temperature phase-change cold storage material capable of being used for cold-chain transportation and preparation method of novel low-temperature phase-change cold storage material

Abstract

The invention relates to the technical field of phase change energy storage materials, in particular to a novel low-temperature phase change cold storage material capable of being used for cold chain transportation and a preparation method thereof.A phase change material base material is prepared from inorganic salt and water according to a certain proportion, and the low-temperature phase change cold storage material is prepared by mixing the base material, a nucleating agent, a thickening agent and a porous medium material according to a certain proportion. The material is wide in source, low in cost and non-toxic, the phase change temperature ranges from-25 DEG C to-20 DEG C, and the material is suitable for transportation of fresh food, vaccines and the like. Meanwhile, by adding the nucleating agent and the thickening agent in a proper proportion, the supercooling degree of the material can be effectively reduced, the heat conductivity is improved, and the phase separation problem existing in the raw materials is effectively relieved. The porous medium material is introduced, a good supporting and dispersing environment is provided for the phase change material, the heat conduction performance of the material is enhanced, the phase separation and material leakage phenomena are inhibited, and the overall energy storage efficiency of the material is improved.

Description

Technical Field

[0001] This invention relates to the field of phase change energy storage materials technology, and more specifically, to a novel low-temperature phase change cold storage material that can be used in cold chain transportation and its preparation method. Background Technology

[0002] Operating temperature range and stability are key factors restricting the development of the cold chain transportation industry. Phase change energy storage technology holds promise as a key breakthrough in overcoming these bottlenecks. Its application in the cold chain transportation industry can not only reduce temperature fluctuations during transportation, thereby effectively reducing product loss, but also help absorb off-peak electricity, achieving peak shaving and valley filling. Low-temperature phase change materials are crucial to phase change energy storage technology and can generally be divided into two main categories: organic phase change materials and inorganic phase change materials.

[0003] Currently, most low-temperature phase change materials used in -20℃ cold chain environments are inorganic hydrated salts. Due to insufficient nucleation sites, their supercooling is generally higher than 5℃, and even reaches 8-10℃ under extreme conditions. This excessive supercooling leads to phase change lag, requiring the material to absorb a large amount of additional sensible heat to trigger the phase change, resulting in temperature fluctuations exceeding ±3℃, seriously threatening the quality and safety of goods such as vaccines and fresh food. Furthermore, phase change cold storage materials have low thermal conductivity, with traditional materials having a thermal conductivity below 0.4 W / (m·K). This results in long charging / discharging cycles, and the low thermal conductivity easily leads to localized heat accumulation, causing large internal temperature gradients, accelerating phase separation, and reducing the lifespan of the phase change cold storage material. Simultaneously, the material's cyclic stability is insufficient; after multiple freeze-thaw cycles, phase separation significantly intensifies, leading to frequent replacements and increased maintenance costs. Therefore, we propose an improvement: a novel low-temperature phase change cold storage material and its preparation method suitable for cold chain transportation. Summary of the Invention

[0004] The purpose of this invention is to address the problems raised in the existing background technology. To achieve the above-mentioned objective, this invention provides the following technical solution: a novel low-temperature phase change cold storage material that can be used in cold chain transportation, comprising, by mass fraction: 75%–80% of a substrate, 0.5%–1% of a nucleating agent, 0.5%–1.5% of a thickener, and 15%–25% of a porous media material; wherein the substrate is a hydrated salt solution, and its components are sodium formate, potassium chloride, or a combination thereof.

[0005] As a preferred embodiment of the present invention, the nucleating agent is one of strontium chloride, barium chloride, titanium dioxide, and aluminum oxide, or a combination thereof.

[0006] As a preferred embodiment of the present invention, the thickener is one or a combination of sodium carboxymethyl cellulose, hydroxyethyl cellulose, nano silica, and sodium polyacrylate.

[0007] As a preferred technical solution of the present invention, the porous media material is one of diatomaceous earth, expanded graphite (EG), aluminum foam, biochar, or a combination thereof.

[0008] As a preferred technical solution of the present invention, the phase change temperature of the low-temperature phase change cold storage material is between -25℃ and -20℃.

[0009] A method for preparing a novel low-temperature phase change cold storage material that can be used in cold chain transportation includes the following steps:

[0010] Step 1: Add the substrate components, nucleating agent, and thickener to distilled water according to the required mass fraction and mix. Stir the mixture in a magnetic stirrer at a water temperature of 40℃~60℃ for 20~40 minutes at a speed of 400rpm~800rpm to form a homogeneous solution.

[0011] Step 2: The porous media material is subjected to high-temperature calcination modification treatment at 350℃~400℃ to increase its specific surface area;

[0012] Step 3: Mix the treated porous media material with the solution obtained in Step 1 at a mass ratio of 1:4 to 1:6, mechanically stir at a speed of 100 to 400 rpm for 2 to 4 hours to obtain a powdered or viscous composite cold storage material.

[0013] As a preferred technical solution of the present invention, in step 1, the water temperature of the magnetic stirrer is 50°C, the rotation speed is 600 rpm, and the stirring time is 30 minutes.

[0014] As a preferred technical solution of the present invention, in step 2, the porous medium material is subjected to high-temperature calcination modification treatment at 380°C.

[0015] As a preferred technical solution of the present invention, in step 3, the mass ratio of the treated porous media material to the solution obtained in step 1 is 1:5, the mechanical stirring speed is 250 rpm, and the stirring time is 3 hours.

[0016] The application of the novel low-temperature phase change cold storage material that can be used in cold chain transportation in the cold chain transportation of fresh food and vaccines.

[0017] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention prepares a phase change material substrate by mixing inorganic salts and water in a certain proportion, and then mixes the substrate, nucleating agent, thickener, and porous media material in a certain proportion to prepare a low-temperature phase change cold storage material. The materials used in this invention are widely available, inexpensive, and non-toxic, and have a phase change temperature of -25 to -20°C, making them suitable for the transportation of fresh food, vaccines, etc. Simultaneously, by adding appropriate proportions of nucleating agent and thickener, the supercooling of the material can be effectively reduced, the thermal conductivity improved, and the phase separation problem of the raw materials effectively mitigated. The introduction of porous media material in this invention provides a good support and dispersion environment for the phase change material, which is beneficial for enhancing the thermal conductivity of the material, suppressing phase separation and material leakage, and improving its overall energy storage efficiency. Attached Figure Description

[0018] Figure 1 A flowchart illustrating the preparation process of a low-temperature phase change cold storage material provided by this invention;

[0019] Figure 2 The DSC curve of the low-temperature phase change material provided by the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0021] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely illustrates some embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. It should be noted that, in the absence of conflict, the embodiments and features and technical solutions in the embodiments of the present invention can be combined with each other. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0022] Example 1: A novel low-temperature phase change cold storage material that can be used in cold chain transportation, comprising, by mass fraction: 75%–80% of a substrate, 0.5%–1% of a nucleating agent, 0.5%–1.5% of a thickener, and 15%–25% of a porous media material; the substrate is a hydrated salt solution, and the components are sodium formate, potassium chloride, or a combination thereof.

[0023] The nucleating agent is one of strontium chloride, barium chloride, titanium dioxide, aluminum oxide, or a combination thereof.

[0024] The thickener is one or a combination of sodium carboxymethyl cellulose, hydroxyethyl cellulose, nano silica, sodium polyacrylate.

[0025] The porous media material is one of diatomaceous earth, expanded graphite (EG), aluminum foam, biochar, or a combination thereof.

[0026] The phase change temperature of low-temperature phase change cold storage materials is between -25℃ and -20℃.

[0027] A method for preparing a novel low-temperature phase change cold storage material that can be used in cold chain transportation includes the following steps:

[0028] Step 1: Add the substrate components, nucleating agent, and thickener to distilled water according to the required mass fraction and mix. Stir the mixture in a magnetic stirrer at a water temperature of 40℃~60℃ for 20~40 minutes at a speed of 400rpm~800rpm to form a homogeneous solution.

[0029] Step 2: The porous media material is subjected to high-temperature calcination modification treatment at 350℃~400℃ to increase its specific surface area;

[0030] Step 3: Mix the treated porous media material with the solution obtained in Step 1 at a mass ratio of 1:4 to 1:6, mechanically stir at a speed of 100 to 400 rpm for 2 to 4 hours to obtain a powdered or viscous composite cold storage material.

[0031] In step 1, the water temperature of the magnetic stirrer is 50℃, the speed is 600rpm, and the stirring time is 30 minutes.

[0032] In step 2, the porous media material is subjected to high-temperature calcination modification treatment at 380℃.

[0033] In step 3, the mass ratio of the treated porous media material to the solution obtained in step 1 is 1:5, the mechanical stirring speed is 250 rpm, and the stirring time is 3 hours. This relates to the application of novel low-temperature phase change cold storage materials suitable for cold chain transportation in the cold chain transportation of fresh food and vaccines.

[0034] Sodium formate, potassium chloride, and distilled water were mixed at a ratio of 22:12:66 by mass and stirred thoroughly at 20°C to form a substrate. Then, 1% strontium chloride (by mass of the substrate) as a nucleating agent and 1% sodium carboxymethyl cellulose as a thickener were added. The mixture was then placed in a 60°C water-temperature magnetic stirrer and stirred at 400 rpm for 20 minutes to form a homogeneous solution, which served as the primary energy storage agent.

[0035] The diatomaceous earth was then calcined in a muffle furnace at 400 degrees Celsius for 2 hours. The calcined diatomaceous earth was then mixed with the resulting solution at a mass ratio of 1:4 and mechanically stirred at 100 rpm for 2 hours to obtain a viscous low-temperature phase change cold storage material.

[0036] The composite cold storage material was subjected to DSC thermal analysis, and the results are shown in the attached figure. Figure 2 As shown, the low-temperature phase change cold storage material has a phase change temperature of -23.1235℃, a latent heat of phase change of 175.14kJ / kg, a supercooling degree of less than 3℃, and a thermal conductivity of greater than 0.7W / m·k.

[0037] Experimental Example

[0038] Experimental Objective

[0039] The performance of the low-temperature phase change cold storage material prepared by this invention is verified, including indicators such as phase change temperature, latent heat of phase change, supercooling degree and thermal conductivity, and the effects of nucleating agent, thickener and porous media material on the material performance are investigated.

[0040] Experimental materials and equipment

[0041] Experimental materials

[0042] Inorganic salts: Sodium formate, potassium chloride

[0043] Nucleating agents: Strontium chloride, barium chloride, titanium dioxide, aluminum oxide

[0044] Thickeners: Sodium carboxymethyl cellulose, hydroxyethyl cellulose, nano silica, sodium polyacrylate; Porous media materials: Diatomaceous earth, expanded graphite (EG), aluminum foam, biochar.

[0045] Distilled water;

[0046] Experimental equipment

[0047] Magnetic stirrer

[0048] muffle furnace

[0049] Mechanical mixer

[0050] Differential Scanning Calorimeter (DSC)

[0051] Thermal conductivity measuring instrument

[0052] Experimental process

[0053] Material formulation

[0054] Substrate: Sodium formate, potassium chloride, and distilled water are prepared in a ratio of 22:12:66 by mass fraction.

[0055] Nucleating agent: Strontium chloride, added at 1% of the substrate mass.

[0056] Thickener: Sodium carboxymethyl cellulose, added at 1% of the base material mass.

[0057] Porous media material: diatomaceous earth, accounting for 24% of the total material mass.

[0058] Preparation steps

[0059] 1. Substrate preparation: Sodium formate, potassium chloride and distilled water are thoroughly stirred in proportion at 20°C to form a substrate.

[0060] 2. Preparation of homogeneous solution: Add nucleating agent and thickener to the substrate, place the mixed solution in a magnetic stirrer at 60°C water temperature, and stir at 400 rpm for 20 minutes to form a homogeneous solution.

[0061] 3. Treatment of porous media materials: Calcine diatomaceous earth in a muffle furnace at 400°C for 2 hours.

[0062] 4. Preparation of composite cold storage material: Calcinated diatomaceous earth and homogeneous solution are mixed at a mass ratio of 1:4 and mechanically stirred at 100 rpm for 2 hours to obtain a viscous low-temperature phase change cold storage material.

[0063] Performance testing

[0064] 1. DSC thermal analysis: The composite cold storage material was tested using a differential scanning calorimeter, and the phase change temperature and latent heat of phase change were recorded.

[0065] 2. Subcooling determination: The subcooling is calculated using DSC thermal analysis data.

[0066] 3. Thermal conductivity measurement: The thermal conductivity of the material is measured using a thermal conductivity meter.

[0067] Comparative experiment

[0068] Samples containing only the substrate were prepared without nucleating agents, thickeners, or porous media. Their performance indicators were measured using the same testing methods and compared with the experimental samples.

[0069] Experimental Results and Analysis

[0070] Performance Indicator Comparison

[0071]

[0072] Results Analysis

[0073] 1. Phase transition temperature: The phase transition temperatures of the experimental samples were all within the range of -25℃ to -20℃, which met the requirements of cold chain transportation, while the phase transition temperatures of the control experimental samples were unstable and too high.

[0074] 2. Phase change latent heat: The phase change latent heat of the experimental sample was significantly higher than that of the control sample, indicating that the addition of nucleating agent, thickener and porous medium material improved the energy storage capacity of the material.

[0075] 3. Supercooling: The supercooling of the comparative experimental sample was larger, while the supercooling of the experimental sample was significantly reduced, indicating that the addition of nucleating agent and thickener effectively suppressed the supercooling phenomenon.

[0076] 4. Thermal conductivity: The thermal conductivity of the experimental sample was significantly higher than that of the control sample, indicating that the introduction of porous media material enhanced the thermal conductivity of the material.

[0077] Experimental conclusions

[0078] This invention successfully prepared a high-performance low-temperature phase change cold storage material by adding nucleating agents and thickeners and introducing porous media material loading. This material possesses a suitable phase change temperature, high latent heat of phase change, low supercooling, and good thermal conductivity, making it suitable for cold chain transportation of fresh food, vaccines, etc. Sodium formate, potassium chloride, and distilled water were mixed thoroughly at 22:12:66 at 20°C to form a substrate. Then, 1% strontium chloride (by weight of the substrate) as a nucleating agent and 1% sodium carboxymethyl cellulose as a thickener were added. The mixture was then placed in a 60°C water-temperature magnetic stirrer and stirred at 400 rpm for 20 minutes to form a homogeneous solution, which served as the primary energy storage agent.

[0079] The diatomaceous earth was then calcined in a muffle furnace at 400 degrees Celsius for 2 hours. The calcined diatomaceous earth was then mixed with the resulting solution at a mass ratio of 1:4 and mechanically stirred at 100 rpm for 2 hours to obtain a viscous low-temperature phase change cold storage material.

[0080] The composite cold storage material was subjected to DSC thermal analysis, and the results are shown in the attached figure. Figure 2 As shown, the low-temperature phase change cold storage material has a phase change temperature of -23.1235℃, a latent heat of phase change of 175.14kJ / kg, a supercooling degree of less than 3℃, and a thermal conductivity of greater than 0.7W / m·k.

[0081] The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described herein. Although the present invention has been described in detail with reference to the above embodiments, the present invention is not limited to the specific embodiments described above. Therefore, any modifications or equivalent substitutions to the present invention, as well as all technical solutions and improvements that do not depart from the spirit and scope of the invention, are covered within the scope of the claims of the present invention.

Claims

1. A novel cryogenic phase change cold storage material useful for cold chain transportation, characterized in that, By mass fraction, including: 75%~80% of the base material, 0.5%~1% of the nucleating agent, 0.5%~1.5% of the thickening agent and 15%~25% of the porous medium material; The base material is a hydrated salt solution, and the components are one or a combination of sodium formate and potassium chloride.

2. A novel low temperature phase change cold storage material useful for cold chain transportation as claimed in claim 1 wherein, The nucleating agent is one or a combination of strontium chloride, barium chloride, titanium dioxide and aluminum oxide.

3. A novel low temperature phase change cold storage material useful for cold chain transportation as claimed in claim 2, wherein, The thickening agent is one or a combination of sodium carboxymethyl cellulose, hydroxyethyl cellulose, nano-silicon dioxide and sodium polyacrylate.

4. A novel low temperature phase change cold storage material useful for cold chain transportation as claimed in claim 3, wherein, The porous medium material is one or a combination of diatomite, expanded graphite EG, foamed aluminum and biochar.

5. A novel low temperature phase change cold storage material useful for cold chain transportation as claimed in claim 4, wherein, The phase transition temperature of the low-temperature phase change cold storage material is between-25 DEG C and-20 DEG C.

6. A method for preparing a novel low-temperature phase change cold storage material for cold chain transportation, characterized in that, The method comprises the following steps: Step 1, the base material component, the nucleating agent, the thickening agent are added into distilled water according to the mass fraction requirement, mixed, stirred in a magnetic stirrer at 40 DEG C~60 DEG C water temperature at 400 rpm~800 rpm speed for 20~40 minutes, and a homogeneous solution is formed; Step 2, the porous medium material is modified by high-temperature calcination at 350 DEG C~400 DEG C to increase its specific surface area; Step 3, the treated porous medium material and the solution obtained in step 1 are mixed at a mass ratio of 1:4~1:6, mechanically stirred, the stirring speed is 100~400 rpm, and the stirring time is 2~4 hours, to obtain a powdery or thick composite cold storage material.

7. The method for preparing a novel low-temperature phase change cold storage material for cold chain transportation according to claim 6, characterized in that, In step 1, the water temperature of the magnetic stirrer is 50 DEG C, the stirring speed is 600 rpm, and the stirring time is 30 minutes.

8. The method for preparing a novel low-temperature phase change cold storage material for cold chain transportation according to claim 7, characterized in that, In step 2, the porous medium material is modified by high-temperature calcination at 380 DEG C.

9. A method for preparing a novel low-temperature phase change cold storage material for cold chain transportation according to claim 8, characterized in that, In step 3, the mass ratio of the treated porous medium material to the solution obtained in step 1 is 1:5, the mechanical stirring speed is 250 rpm, and the stirring time is 3 hours.

10. The application of the novel low-temperature phase change cold storage material for cold chain transportation according to any one of claims 1~5 in food fresh and vaccine cold chain transportation.

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