Ultralow-temperature solid-liquid phase change cold storage material and preparation method thereof

Abstract

The invention relates to the technical field of refrigeration materials, in particular to an ultralow-temperature solid-liquid phase change cold storage material and a preparation method thereof. Comprising a mixture of any two of a ZnCl2 aqueous solution, a FeCl3 aqueous solution and a NaCl aqueous solution. Compared with the prior art, the phase-change material formed by mixing the raw materials has different formulas, the phase-change temperature of the phase-change material can range from-21 DEG C to-62 DEG C, the ultra-low-temperature phase-change temperature is achieved, and the comprehensive solid-liquid phase-change temperature of the phase-change cold storage material can be flexibly adjusted. And in an ultralow-temperature energy storage working environment, the cold storage device has a long-service-life and high-stability cold storage function.

Description

Technical Field

[0001] The present invention relates to the technical field of refrigeration materials, in particular to an ultra-low temperature solid-liquid phase change cold storage material and a preparation method thereof. Background Art

[0002] With the growth of population and the continuous development of social economy, the shortage and rational utilization of energy have become urgent issues. Energy storage technology is an important means of saving energy. Among them, thermal energy technology is relatively mature and plays an important role in power systems, industrial waste heat recovery, solar thermal utilization and other fields. Another direction is cold energy storage technology, which is mainly used in food refrigeration, air-conditioning systems, medical cold chain and other fields. Common cold energy storage methods include mechanical refrigeration and adsorption refrigeration. Phase change energy storage has attracted more and more attention due to its high efficiency and stability. Latent heat storage absorbs and releases heat through the phase change of materials. Compared with traditional chemical reactions and sensible heat storage, it has the advantages of higher safety, high energy storage density and constant temperature.

[0003] The melting and solidification processes absorb and release heat, maintaining a relatively stable ambient temperature and enabling temperature control in specific applications. In recent years, advances in medical technology have led to the emergence of new bioactive drugs. These drugs present significant challenges in research and development, requiring demanding storage conditions, often requiring storage and transportation at temperatures of -50°C or lower. Furthermore, demand for cold and ultra-low temperature storage facilities is growing in areas such as deep-sea fish storage, cold chain transportation, and ultra-low temperature industries. However, the high operating costs of ultra-low temperature refrigeration equipment hinder its development, indirectly increasing transportation costs and hindering industrial development. By developing ultra-low temperature cold storage materials, utilizing low-cost clean electricity such as wind power and photovoltaics for cooling, and storing the cold energy for application, operating costs can be significantly reduced. However, due to the demanding conditions for ultra-low temperature cold storage, research and application of phase change materials operating at temperatures of -50°C or below is limited.

[0004] At present, ultra-low temperature cold storage materials are mainly organic substances such as alkanes, polyols, and fatty acids. These materials generally have the problem of high cost. For example, the invention patent with publication number CN111826126A synthesizes cold storage phase change materials by mixing two or three of ketones, aldehydes and alkanes. The invention patent with publication number CN111205828B prepares cold storage phase change materials by mixing two or three of esters, alcohols and alkanes, which can meet the phase change requirements below minus 50°C. However, on the one hand, most organic materials are mainly in the gas phase at room temperature. On the other hand, organic phase change materials generally have poor thermal conductivity, low density, and are flammable, which poses safety risks when used.

[0005] To address these shortcomings, technologies have been developed that utilize aqueous solutions containing inorganic salts as low-temperature cold storage materials. For example, patent application CN116515460A uses lithium chloride as the primary temperature-regulating material, resulting in a phase-change material with a phase transition temperature of -65°C to -63°C. However, lithium chloride has a narrow thermal stability window and is prone to structural transformation or decomposition at high temperatures. This leads to technical challenges in the application of this system, including poor cold storage uniformity and stability, and the risk of failure due to uneven phase transitions. Patent application CN2022116605314 proposes a composite phase-change material using lithium chloride as the temperature-regulating material, diethylene glycol as the dispersant, water as the main material, titanium dioxide or expanded graphite as the thermally conductive reinforcement, and carboxymethyl cellulose, hydroxyethyl cellulose, or sodium carboxymethyl cellulose as the thickener. This composite material can achieve ultra-low-temperature cold storage at -63°C to -65°C. However, the lithium chloride in this technology exhibits strong hygroscopicity and easily absorbs water in humid environments, resulting in a sharp drop in ionic conductivity and affecting performance. In addition, its main material is water, accounting for more than 50%, which may cause phase separation during repeated use. For example, some hydrated salt crystals may sink to the bottom and fail to recrystallize, resulting in a decrease in the cold storage capacity of the phase change material. In addition, the high cost of lithium chloride material leads to high cost of the prepared phase change material, which is not conducive to commercial application.

[0006] In view of the above bottlenecks, the present invention proposes an ultra-low temperature solid-liquid phase change cold storage material and a preparation method, which has a long life and highly stable cold storage function in an ultra-low temperature energy storage working environment. Summary of the Invention

[0007] In order to overcome the deficiencies of the prior art, the present invention provides an ultra-low temperature solid-liquid phase change cold storage material and a preparation method thereof.

[0008] To achieve the above purpose, an ultra-low temperature solid-liquid phase change cold storage material is designed, which includes a mixture of any two aqueous solutions among ZnCl2 aqueous solution, FeCl3 aqueous solution and NaCl aqueous solution.

[0009] The concentration of the ZnCl2 aqueous solution is 51.0±2%, the concentration of the FeCl3 aqueous solution is 33.1±1%, and the concentration of the NaCl aqueous solution is 22.4±1%.

[0010] By changing the Zn 2+ 、Fe 3+ 、Na + and Cl - The concentration ratio can obtain different phase transition temperatures between -21℃ and -62℃.

[0011] It also includes a viscosity regulator with a molar ratio of 0.5-10%, a nucleating agent with a molar ratio of 0.3-3%, and a thermal conductivity adjustment material with a molar ratio of 1-7%.

[0012] The viscosity modifier is selected from one of carboxymethyl cellulose CMC, polyacrylamide PAM, and carbon black; the nucleating agent is selected from one or more of ammonium chloride, silicon oxide, aluminum oxide, titanium oxide, iron oxide, copper oxide, magnesium oxide, and zinc oxide; the thermal conductivity adjustment material is selected from high thermal conductivity nanomaterials, including but not limited to one or more of graphene, single-walled carbon nanotubes, diamond or diamond-like particles, and conductive carbon black.

[0013] Including a mixed solution of ZnCl2 aqueous solution and FeCl3 aqueous solution, Zn 2+ with Fe 3+ The molar ratio can be adjusted in the range of 0-100%, and the adjustment accuracy of the molar ratio can reach 1%. - With Zn 2+ and Fe 3+ The chemical equivalent ratio is satisfied, and the phase transition temperature of the mixed solution is between -55°C and -62°C. The phase transition temperature can be adjusted by adjusting the content of the ZnCl2 aqueous solution and the FeCl3 aqueous solution.

[0014] Including a mixed solution of NaCl aqueous solution and FeCl3 aqueous solution, Na + with Fe 3+ The molar ratio can be adjusted in the range of 0-100%, and the adjustment accuracy of the molar ratio can reach 1%. - with Na + and Fe 3+ The chemical equivalent ratio is satisfied, and the phase transition temperature of the mixed solution is between -21°C and -55°C. The phase transition temperature can be adjusted by adjusting the content of the NaCl aqueous solution and the FeCl3 aqueous solution.

[0015] To achieve the above objectives, a method for preparing an ultra-low temperature solid-liquid phase change cold storage material is designed, comprising the following steps: S1, respectively preparing any two aqueous solutions of ZnCl2 aqueous solution, FeCl3 aqueous solution and NaCl aqueous solution to the required concentration; S2, mixing the aqueous solutions prepared in step S1 and stirring them thoroughly at room temperature; S3, after uniform mixing, add a viscosity modifier and stir in a container or environment without gas flow; S4, adding the corresponding aqueous solution in step S1 according to the required phase transition temperature to adjust the phase transition point of the mixed solution; S5, adding a nucleating agent and a thermal conductivity adjusting material to the mixed solution in sequence, and stirring the mixture evenly.

[0016] Compared to existing technologies, this invention utilizes a different formulation for the phase-change material, resulting from a mixture of raw materials. Its phase-change temperature can be adjusted between -21°C and -62°C, achieving ultra-low temperatures. This allows for flexible adjustment of the combined solid-liquid phase-change temperature of the phase-change cold storage material. Furthermore, the invention provides a long-life, highly stable cold storage function in ultra-low-temperature energy storage environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a curve showing the temperature change over time when the phase change material with a solid-liquid phase transition temperature of -60°C releases heat and stores cold in Example 1 of the present invention.

[0018] Figure 2 The following are the curves showing the change in cooling capacity released by the phase change material with a solid-liquid phase transition temperature of -60°C in Example 1 of the present invention at temperatures of -20°C, -10°C, and 5°C respectively after storing cooling at about -108°C.

[0019] Figure 3 This is a curve showing the temperature change over time when the phase change material with a solid-liquid phase transition temperature of -50°C releases heat and stores cold in Example 2 of the present invention.

[0020] Figure 4 The following are the changing curves of the phase change material with a solid-liquid phase transition temperature of -50°C in Example 2 of the present invention, after storing cold at about -106°C, and releasing cold at temperatures of -20°C, -10°C, and 5°C respectively.

[0021] Figure 5 This is a curve showing the temperature change over time when the phase change material with a solid-liquid phase transition temperature of -40°C releases heat and stores cold in Example 3 of the present invention.

[0022] Figure 6 This is a curve showing the change in cooling capacity released by the phase change material with a solid-liquid phase transition temperature of -40°C in Example 3 of the present invention at temperatures of -20°C, -10°C, and 5°C respectively after storing cooling at about -107°C. DETAILED DESCRIPTION

[0023] The present invention will be further described below with reference to the accompanying drawings.

[0024] The ultra-low-temperature solid-liquid phase-change cold storage material of the present invention comprises a mixture of any two of an aqueous ZnCl₂ solution, an aqueous FeCl₃ solution, and an aqueous NaCl solution. It also contains 0.5-10% by mole of a viscosity modifier, 0.3-3% by mole of a nucleating agent, and 1-7% by mole of a thermal conductivity adjusting material. The ZnCl₂ solution, FeCl₃ solution, and NaCl solution act as phase-change temperature regulators, and temperature regulation is achieved by controlling their ratio.

[0025] The concentration of ZnCl2 aqueous solution is 51.0±2%, the concentration of FeCl3 aqueous solution is 33.1±1%, and the concentration of NaCl aqueous solution is 22.4±1%. The melting point of ZnCl2 aqueous solution with a concentration of 51% is -62℃, the melting point of FeCl3 aqueous solution with a concentration of 33.1% is -55℃, and the melting point of NaCl aqueous solution with a concentration of 22.4% is -21℃. 2+ 、Fe 3+ 、Na + and Cl - The concentration ratio can obtain different phase transition temperatures between -21℃ and -62℃.

[0026] Viscosity modifiers increase viscosity and prevent the precipitation of salt crystals. Carboxymethyl cellulose (CMC), polyacrylamide (PAM), or carbon black are selected. Different nucleating agents regulate different temperatures. The desired temperature can be adjusted by changing the type of nucleating agent. Nucleating agents can be selected from one or more of ammonium chloride, silicon oxide, aluminum oxide, titanium oxide, iron oxide, copper oxide, magnesium oxide, and zinc oxide. By controlling the nucleating agent addition amount to 0.3-3%, the low-temperature transition range of the mixed phase change material can reach -35 to -62°C. Thermal conductivity adjustment materials adjust the uniformity of the mixed phase change material. Highly thermally conductive nanomaterials are selected, including but not limited to one or more of graphene, single-walled carbon nanotubes, diamond or diamond-like particles, and conductive carbon black.

[0027] When used specifically, a mixed solution of ZnCl2 aqueous solution and FeCl3 aqueous solution, Zn 2+ with Fe 3+ The molar ratio can be adjusted in the range of 0-100%, and the adjustment accuracy of the molar ratio can reach 1%. - With Zn 2+ and Fe 3+ The chemical equivalent ratio is satisfied, and the phase transition temperature of the mixed solution is between -55°C and -62°C. The phase transition temperature can be adjusted by adjusting the content of the ZnCl2 aqueous solution and the FeCl3 aqueous solution.

[0028] When used specifically, a mixed solution of NaCl aqueous solution and FeCl3 aqueous solution, Na + with Fe 3+ The molar ratio can be adjusted in the range of 0-100%, and the adjustment accuracy of the molar ratio can reach 1%. - with Na + and Fe 3+ The chemical equivalent ratio is satisfied, and the phase transition temperature of the mixed solution is between -21°C and -55°C. The phase transition temperature can be adjusted by adjusting the content of the NaCl aqueous solution and the FeCl3 aqueous solution.

[0029] The preparation method of the ultra-low temperature solid-liquid phase change cold storage material comprises the following steps: S1, respectively preparing any two aqueous solutions of ZnCl2 aqueous solution, FeCl3 aqueous solution and NaCl aqueous solution to the required concentration; S2, mixing the aqueous solutions prepared in step S1 and stirring them thoroughly at room temperature; S3, after uniform mixing, add a viscosity modifier and stir in a container or environment without gas flow; S4, adding the corresponding aqueous solution in step S1 according to the required phase transition temperature to adjust the phase transition point of the mixed solution; S5, adding a nucleating agent and a thermal conductivity adjusting material to the mixed solution in sequence, and stirring the mixture evenly.

[0030] NaCl is a commonly used refrigerant, while ZnCl2 and FeCl3 are not usually used as refrigerants. ZnCl2 and FeCl3 dissociate into ions in water. These ions interfere with the crystallization process of water molecules, causing the freezing point of the solution to decrease. The hydrated salts of sodium chloride and potassium chloride themselves undergo phase change and cold storage at ultra-low temperatures and are unstable. The present invention utilizes the supercooling phenomenon of zinc chloride and ferric chloride hydrates at ultra-low temperatures (below -40°C), that is, the change in the freezing point and melting point temperature of the liquid-solid phase, resulting in the drift of the endothermic and exothermic phase change temperature points, thereby enabling the mixed refrigerant to reach a new temperature range and achieve the effect of cold storage.

[0031] The higher the purity of the chloride salt hydrate, the more difficult it is to control the phase transition temperature. This drift in the phase transition temperature makes it difficult for the cold storage system to precisely control the phase transition process, reducing the efficiency of energy storage and release. Therefore, the present invention adds materials such as nucleating agents, viscosity additives, and phase transition temperature regulators, while also adjusting the chloride salt concentration to alter the solution's crystallization dynamics. This not only improves the material's phase transition uniformity but also enables stable phase change cold storage within a low-temperature range. Example 1

[0032] In this embodiment, a phase change material with a phase change temperature of -60°C is prepared by precisely adjusting the molar ratio of ZnCl2 and FeCl3 and their concentrations in aqueous solution.

[0033] In this embodiment, a mixture of an 80% by molar ratio ZnCl₂ aqueous solution and a 20% by molar ratio FeCl₃ aqueous solution was selected, and 0.5% by molar ratio polyacrylamide was added as a viscosity modifier, 0.4% by molar ratio silicon oxide was added as a nucleating agent, and 1.5% by molar ratio graphene was added as a thermal conductivity adjustment material. The mixture was stirred uniformly at room temperature to prepare a solid-liquid cold storage material having a solid-liquid phase transition temperature of approximately -60°C. The concentration of the ZnCl₂ aqueous solution was 51.0±2%, and the concentration of the FeCl₃ aqueous solution was 33.1±1%.

[0034] Using liquefied natural gas (LNG) as a cold source material, the cold storage performance of the solid-liquid cold storage material obtained in this embodiment was tested. The test results are as follows: Figure 1-2 shown. Figure 1 This is the result of the heat release and cold storage test of the phase change material with a phase change temperature of -60°C. It can be seen that the temperature of the phase change material changes with time. When liquefied natural gas (LNG) is used to cool the liquid phase change material, the phase change material reaches the phase change point of about -60°C after 2 hours of continuous cooling. After about 5 hours of continuous cold storage, the phase change material is completely solidified, achieving the purpose of phase change cold storage. Subsequent further refrigeration leads to a decrease in the temperature of the phase change material after solidification.

[0035] Figure 2 The curves show how the phase change material, with a solid-liquid phase transition point of -60°C, releases cooling energy at -20°C, -10°C, and 5°C, respectively, after storing cooling energy at -108°C. These curves correspond to applications in cold storage, refrigerated storage, and fresh-keeping environments, respectively. Targeting a -20°C cold storage environment, the liquid flows through the hybrid phase change material, transferring cooling energy from the phase change material to the surrounding environment. This cooling energy is regulated to maintain the cold storage temperature at -20°C. Figure 2 It shows that with the transportation of cold energy, after 2.5 hours, the temperature of the phase change material rises from -108°C to the phase change point of -60°C. The phase change material then continues to cool (absorb heat) for about 4.5 hours, and the material changes from solid to liquid. After that, the liquid phase change material continues to cool for about 4 hours, and the final temperature is close to -22°C.

[0036] When establishing a -10℃ refrigerated environment, Figure 2 The curve shows that after transferring cold energy from the phase change material to the environment, the temperature of the phase change material rises from -108°C to the phase transition point of -60°C over 2.5 hours. After approximately 4.2 hours of continuous cooling, the material transitions from solid to liquid. After approximately 4.3 hours of cooling, the liquid phase change material reaches a final temperature of approximately -13°C. During this process, the refrigerated environment temperature is maintained at -10°C by regulating the delivery of cold energy. When establishing a 5°C insulation environment, the same goal of regulating the delivery of cold energy over a 2.5-hour to 4-hour to 4.5-hour period is achieved, ultimately maintaining the refrigerated environment temperature at 5°C. Example 2

[0037] In this embodiment, a phase change material with a phase change temperature of -50°C is prepared by precisely adjusting the molar ratio of NaCl and FeCl3 and the concentration in the aqueous solution.

[0038] In this embodiment, a 13% molar NaCl aqueous solution and an 87% molar FeCl3 aqueous solution were mixed, and 0.5% molar polyacrylamide was added as a viscosity modifier, 0.4% molar silicon oxide was added as a nucleating agent, and 1.5% molar graphene was added as a thermal conductivity adjustment material. The mixture was stirred evenly at room temperature. The resulting solid-liquid cold storage material had a solid-liquid phase transition temperature of approximately -50°C. The concentration of the NaCl aqueous solution was 22.4±1%, and the concentration of the FeCl3 aqueous solution was 33.1±1%.

[0039] Using LNG as a cold source, the cold storage performance of the solid-liquid cold storage material obtained in this embodiment was tested. The test results are as follows: Figure 3-4 shown.

[0040] Figure 3 The following figure shows the heat release and cold storage test results for a phase change material with a phase transition temperature of -50°C. The temperature change curve of the phase change material over time shows that after LNG was used to cool the liquid phase change material, the material reached its phase transition point of approximately -50°C after 1.7 hours of continuous cooling. After approximately 5 hours of continuous cold storage, the phase change material completely solidified, achieving the phase change cold storage purpose. Subsequent cooling caused the temperature of the solidified phase change material to drop.

[0041] Figure 4 The phase change material with a solid-liquid phase transition point of -50°C is subjected to cold storage at -106°C, and releases cold energy at temperatures of -20°C, -10°C, and 5°C, respectively, corresponding to applications in cold storage, refrigeration, and fresh-keeping environments.

[0042] A cold storage environment of -20℃ is established. The cold energy is transferred from the phase change material to the environment through the mixed phase change material through the liquid flow. By adjusting the transfer of cold energy, the temperature of the cold storage is maintained at -20℃. Figure 4 The data shows that as the cooling energy is delivered, the temperature of the phase change material rises from -106°C to the phase transition point of -50°C over 2.7 hours. After approximately 4.3 hours of continuous cooling (heat absorption), the material transitions from solid to liquid. After approximately 3.5 hours of cooling, the liquid phase change material reaches a final temperature of approximately -20°C. Similarly, under the same conditions, the temperature can be maintained at a -10°C refrigeration environment or a 5°C insulation environment. Example 3

[0043] In this embodiment, a phase change material with a phase change temperature of -40°C is prepared by precisely adjusting the molar ratio of NaCl and FeCl3 and the concentration in the aqueous solution.

[0044] In this embodiment, a mixture of a 30% molar NaCl aqueous solution and a 70% molar FeCl₃ aqueous solution was prepared. 0.5% molar polyacrylamide was added as a viscosity modifier, 0.4% molar silicon oxide was added as a nucleating agent, and 1.5% molar graphene was added as a thermal conductivity adjustment material. The mixture was stirred evenly at room temperature. The resulting solid-liquid cold storage material had a solid-liquid phase transition temperature of approximately -50°C. The concentration of the NaCl aqueous solution was 22.4±1%, and the concentration of the FeCl₃ aqueous solution was 33.1±1%.

[0045] Using LNG as a cold source, the cold storage performance of the solid-liquid cold storage material obtained in this embodiment was tested. The test results are as follows: Figure 5-6 shown.

[0046] Figure 5 The results of a heat release and cold storage test of a phase change material with a phase transition temperature of -40°C show how the material's temperature changes over time. After refrigerating the liquid phase change material with LNG, the material reached its phase transition point of approximately -40°C after 1.7 hours of continuous cooling. After approximately 5 hours of continuous cold storage, the material completely solidified, achieving the phase change cold storage goal. Subsequent cooling lowered the temperature of the solidified phase change material.

[0047] Figure 6 This is the change curve of the phase change material with a solid-liquid phase transition point of -40°C releasing cold capacity at temperatures of -20°C, -10°C, and 5°C respectively after storing cold at -107°C, corresponding to applications in cold storage, refrigeration, and preservation environments.

[0048] A cold storage environment of -20℃ is established. The cold energy is transferred from the phase change material to the environment through the mixed phase change material through the liquid flow. By adjusting the transfer of cold energy, the temperature of the cold storage is maintained at -20℃. Figure 6 It shows that with the transportation of cold energy, after 2.8 hours, the temperature of the phase change material rises from -107°C to the phase change point of -40°C. The phase change material then continues to cool (absorbs heat) for about 4 hours, and the material changes from solid to liquid. After that, the liquid phase change material continues to cool for about 3 hours, and the final temperature reaches -20°C.

[0049] A refrigerated environment of -10°C was established, and the cold energy was transferred from the phase change material to the environment. After 2.8 hours, the temperature of the phase change material rose from -107°C to the phase change point of -40°C. The phase change material was then continuously cooled for about 4 hours, and the material changed from solid to liquid. After that, the liquid phase change material was cooled for about 3 hours, and the final temperature reached -10°C, maintaining the temperature of the refrigerated environment at -10°C.

[0050] A 5°C insulation environment is established, and a special liquid is used to transport cold air from the phase change material to the environment. After 2.7 hours, the temperature of the phase change material rises from -107°C to the phase change point of -40°C. The phase change material is then cooled continuously for about 4 hours, and the material changes from solid to liquid. After that, the liquid phase change material is cooled for about 3.3 hours, and the final temperature reaches 5°C, maintaining the temperature of the refrigerated environment at 5°C.

Claims

1. An ultra-low temperature solid-liquid phase change cold storage material, characterized by: The method comprises mixing any two aqueous solutions selected from the group consisting of a ZnCl2 aqueous solution, a FeCl3 aqueous solution and a NaCl aqueous solution.

2. The ultra-low temperature solid-liquid phase change cold storage material according to claim 1, characterized in that: The concentration of the ZnCl2 aqueous solution is 51.0±2%, the concentration of the FeCl3 aqueous solution is 33.1±1%, and the concentration of the NaCl aqueous solution is 22.4±1%.

3. The ultra-low temperature solid-liquid phase change cold storage material according to claim 1, characterized in that: By changing the Zn 2+ 、Fe 3+ 、Na + and Cl - The concentration ratio can obtain different phase transition temperatures between -21℃ and -62℃.

4. The ultra-low temperature solid-liquid phase change cold storage material according to claim 1 or 2, characterized in that: It also includes a viscosity regulator with a molar ratio of 0.5-10%, a nucleating agent with a molar ratio of 0.3-3%, and a thermal conductivity adjustment material with a molar ratio of 1-7%.

5. The ultra-low temperature solid-liquid phase change cold storage material according to claim 3, characterized in that: The viscosity modifier is selected from one of carboxymethyl cellulose CMC, polyacrylamide PAM, and carbon black; the nucleating agent is selected from one or more of ammonium chloride, silicon oxide, aluminum oxide, titanium oxide, iron oxide, copper oxide, magnesium oxide, and zinc oxide; the thermal conductivity adjustment material is selected from high thermal conductivity nanomaterials, including but not limited to one or more of graphene, single-walled carbon nanotubes, diamond or diamond-like particles, and conductive carbon black.

6. The ultra-low temperature solid-liquid phase change cold storage material according to claim 1 or 2, characterized in that: Including a mixed solution of ZnCl2 aqueous solution and FeCl3 aqueous solution, Zn 2+ with Fe 3+ The molar ratio can be adjusted in the range of 0-100%, and the adjustment accuracy of the molar ratio can reach 1%. - With Zn 2+ and Fe 3+ The chemical equivalent ratio is satisfied, and the phase transition temperature of the mixed solution is between -55°C and -62°C. The phase transition temperature can be adjusted by adjusting the content of the ZnCl2 aqueous solution and the FeCl3 aqueous solution.

7. The ultra-low temperature solid-liquid phase change cold storage material according to claim 1 or 2, characterized in that: Including a mixed solution of NaCl aqueous solution and FeCl3 aqueous solution, Na + with Fe 3+ The molar ratio can be adjusted in the range of 0-100%, and the adjustment accuracy of the molar ratio can reach 1%. - with Na + and Fe 3+ The chemical equivalent ratio is satisfied, and the phase transition temperature of the mixed solution is between -21°C and -55°C. The phase transition temperature can be adjusted by adjusting the content of the NaCl aqueous solution and the FeCl3 aqueous solution.

8. A method for preparing the ultra-low temperature solid-liquid phase change cold storage material according to any one of claims 1 to 7, characterized in that: The steps include: S1, respectively preparing any two aqueous solutions of ZnCl2 aqueous solution, FeCl3 aqueous solution and NaCl aqueous solution to the required concentration; S2, mixing the aqueous solutions prepared in step S1 and stirring them thoroughly at room temperature; S3, after uniform mixing, add a viscosity modifier and stir in a container or environment without gas flow; S4, adding the corresponding aqueous solution in step S1 according to the required phase transition temperature to adjust the phase transition point of the mixed solution; S5, adding a nucleating agent and a thermal conductivity adjusting material to the mixed solution in sequence, and stirring the mixture evenly.

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