Composite phase change material for high-temperature operation cooling equipment and preparation method of composite phase change material

Abstract

The invention belongs to the technical field of phase change materials, and discloses a composite phase change material for high-temperature operation cooling equipment, which comprises the following components in parts by weight: 75-85 parts of a main energy storage agent, 2-5 parts of a nucleating agent, 3-6 parts of a thickening setting agent, 0.2-5 parts of a heat conduction enhancer, 5-10 parts of deionized water, 0.5-2 parts of other functional materials and a shape stable matrix. The eutectic modification technology is adopted, sodium sulfate decahydrate and potassium chloride / ammonium chloride are compounded, the phase change temperature is precisely regulated and controlled in a human body comfortable area, the cold shock reaction and frostbite risks of a traditional ice bag are thoroughly avoided, and the pain point that unmodified pure sodium sulfate decahydrate is ineffective in cooling is solved; the flammable hidden danger of paraffin materials is avoided, the device is suitable for high-temperature spark operation scenes, and collaborative breakthrough of safety and comfort is achieved; the high latent heat characteristic of sodium sulfate decahydrate is still stable after modification, and the sodium sulfate decahydrate is matched with graphene, expanded graphite and carbon nanotubes to construct a point-surface-body composite heat conduction network.

Description

Technical Field

[0001] This invention belongs to the field of phase change material technology, specifically a composite phase change material for high-temperature operation cooling equipment and its preparation method. Background Technology

[0002] In high-temperature environments such as metallurgy, glass manufacturing, fire rescue, power inspection, and summer outdoor operations, workers are exposed to high ambient temperatures for extended periods, facing significant risks of heatstroke, dehydration, and even heat exhaustion, which seriously threaten their work safety and health.

[0003] Currently, mainstream human body cooling equipment is mainly divided into two categories: air-cooled clothing and liquid-cooled clothing. Air-cooled clothing uses fans to drive airflow for heat dissipation, but its cooling effect significantly decreases or even reverses when the ambient temperature is higher than body temperature (37°C). Liquid-cooled clothing relies on circulating liquid to remove heat, but the system requires pumps, pipes, and other components, resulting in a complex and heavy overall structure. Furthermore, the pumps and pipes restrict the operator's range of motion, limiting its applicability. Therefore, passive cooling equipment based on phase change materials with cold storage capabilities (such as phase change cooling vests) has become popular due to its simple structure, portability, and lack of external energy supply. High-temperature operation cooling is a research hotspot; however, existing phase change materials used in cooling equipment still have the following key drawbacks: poor temperature matching; commonly used ice pack-type phase change materials (phase change temperature 0℃) have too large a temperature difference with the human body, easily causing skin vasoconstriction (cold shock reaction) or even frostbite upon contact, and condensation on the surface easily leads to discomfort when worn; while pure inorganic hydrated salts that have not undergone eutectic modification (such as sodium sulfate decahydrate) have a relatively high phase change temperature (about 32℃), which cannot meet the human body's comfortable cooling needs and makes it difficult to achieve precise temperature control; there is a contradiction between safety and thermal conductivity, as ordinary paraffin-based phase change materials have low thermal conductivity (usually <0.3W / (m²)). Furthermore, it is flammable and unsuitable for high-temperature spark environments such as welding, metallurgy, and firefighting. While traditional inorganic hydrated salts are non-flammable, their poor thermal conductivity leads to slow endothermic response and insufficient cooling timeliness. Phase separation and supercooling are prominent issues; although inexpensive inorganic hydrated salts have high latent heat (>200 J / g), they are prone to salt-water stratification (phase separation) after multiple endothermic and exothermic cycles, resulting in decreased heat storage and release performance. Simultaneously, they exhibit severe supercooling (not crystallizing even 10°C below the freezing point), making them difficult to recover naturally after being removed from high-temperature environments and unusable. Existing single nucleating agents cannot effectively control supercooling. They also lack shape stability and leak-proof capabilities, with most phase changes... After phase change, the material becomes liquid. If the packaging bag is damaged, leakage is likely to occur, affecting operational safety. Moreover, existing shape stabilization solutions mostly rely on a single porous material load or simple gel thickening, lacking a synergistic design of "macroscopic support-microscopic locking". A single porous material can only maintain the macroscopic shape and cannot suppress phase separation caused by the diffusion of internal salt ions. Although simple gel thickening can temporarily lock the components, it is prone to losing elasticity after long-term cycling, resulting in shape shrinkage and deformation, ultimately increasing the thermal resistance in contact with the human body and significantly reducing the cooling effect. Therefore, there is an urgent need for a composite phase change material that can achieve precise temperature matching, rapid heat conduction, no supercooling, stable cycling, controllable shape, and is safe and non-flammable, in order to solve the multiple pain points of existing technologies. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention employs a composite modification strategy of "porous framework loading + eutectic hydrated salt + nucleating agent + thickener + thermal conductivity enhancer" to achieve synergistic design and functional integration of multi-scale structures at the macro-, micro-, and nano-scale levels. This invention provides a composite phase change material for high-temperature cooling equipment and its preparation method, which possesses advantages such as precise temperature matching, high latent heat, good thermal conductivity, no supercooling, high cycle stability, good shape stability, and non-flammability.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a composite phase change material for high-temperature operation cooling equipment, comprising the following components in parts by weight: 75-85 parts of main energy storage agent, 2-5 parts of nucleating agent, 3-6 parts of thickening and shaping agent, 0.2-5 parts of thermal conductivity enhancer, 5-10 parts of deionized water, 0.5-2 parts of other functional materials, and a shape-stabilizing matrix; wherein the main energy storage agent is a mixture of sodium sulfate decahydrate and a temperature regulator, and the temperature regulator is potassium chloride and / or ammonium chloride; the nucleating agent is a mixture of borax and nano-titanium dioxide; the thickening and shaping agent is a compound of sodium polyacrylate and sodium carboxymethyl cellulose or fumed silica; and the thermal conductivity enhancer is graphene, or a composition of graphene with at least one of expanded graphite and carbon nanotubes.

[0006] Preferably, the main energy storage agent is sodium sulfate decahydrate and potassium chloride, with a mass ratio of sodium sulfate decahydrate to potassium chloride of 9:1.

[0007] Preferably, the other functional materials are selectively added, and the other functional materials are thermochromic materials.

[0008] Preferably, the shape-stabilizing matrix is ​​hydrophilic melamine foam with an open porosity of 99%.

[0009] A method for preparing a composite phase change material for high-temperature cooling equipment includes the following steps: Step 1: Preparation of eutectic salt Weigh each component according to the mass fraction: main energy storage agent, nucleating agent, thickening and shaping agent, thermal conductivity enhancer, and deionized water; optionally, weigh the thermosensitive color-changing material; prepare hydrophilic melamine foam as a shape-stabilizing matrix; Add the weighed sodium sulfate decahydrate and temperature regulator to deionized water, and stir and mix for 30-60 minutes under constant temperature conditions of 40-50℃ water bath until completely dissolved to form a transparent and uniform eutectic salt solution. Step 2: Suppressing Undercooling Slowly add the ground nucleating agent to the eutectic salt solution obtained in step one, maintain the temperature and disperse by high-speed shearing and stirring; Step 3: Thermal conductivity and functional modification First, add a thermal conductivity enhancer and a thermochromic material to the solution obtained in step two, and sonicate for 10-15 minutes. Then, add a thickening and shaping agent, reduce the stirring speed to 200-300 rpm, and stir until the mixture presents a uniform viscous gel and no flowing liquid is separated. Then, impregnate the hydrophilic melamine foam into the gel, adsorb and load it under vacuum, and scrape off the excess gel on the surface after taking it out. Step 4: Shaping and Packaging After vacuum degassing of the loaded gel phase change material in step three, it is packed into a TPU or aluminum-plastic composite film bag and heat-sealed to obtain the finished product.

[0010] Preferably, the stirring and mixing rate in step one is 500-800 rpm. During the stirring process, the transparency of the solution is continuously monitored until there are no visible particles in the solution and the refractive index is uniform, ensuring that the sodium sulfate decahydrate and the temperature regulator are completely eutectic fused.

[0011] Preferably, the particle size of the nucleating agent after grinding in step two is no greater than 5 μm, to ensure that it is uniformly dispersed in the eutectic salt solution and provides sufficient heterogeneous nucleation sites.

[0012] Preferably, the stirring speed in step two is 800-1000 rpm, and the stirring time is 15 minutes.

[0013] Preferably, the thermochromic material in step one is a microencapsulated reversible thermochromic paste with a color-changing temperature of 23±2℃.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. By employing eutectic modification technology, sodium sulfate decahydrate is compounded with potassium chloride / ammonium chloride, precisely controlling the phase transition temperature within the human comfort zone of 21-25℃. This completely avoids the cold shock and frostbite risks associated with traditional ice packs, while also addressing the ineffective cooling effect of unmodified pure sodium sulfate decahydrate. Furthermore, the main material is a non-flammable inorganic salt, eliminating the flammability hazards of paraffin-based materials, making it suitable for high-temperature spark-prone work environments and achieving a synergistic breakthrough in safety and comfort. Simultaneously, the high latent heat characteristic of sodium sulfate decahydrate remains stable at 158-172 J / g after modification. Combined with a "point-surface-volume" composite thermal conductive network constructed from graphene, expanded graphite, and carbon nanotubes, the thermal conductivity is increased to 2.0-4.5 W / (m²). Compared to traditional materials, this material (K) offers a significant improvement, balancing long-lasting cooling performance with rapid heat absorption response, thus resolving the inherent contradiction between endurance and response in existing materials. Furthermore, through a composite nucleation system of borax and nano-titanium dioxide, it synergistically provides ample heterogeneous nucleation sites, reducing supercooling to 0.8-1.4℃, far superior to traditional single nucleating agents. This ensures that the material can rapidly re-crystallize at normal room temperature, completely solving the industry problem of "severe supercooling and difficulty in reusing" of inorganic hydrated salts.

[0015] 2. By constructing a dual stabilization system of "macroscopic porous framework loading + microscopic gel network locking," the macroscopic level uses hydrophilic melamine foam with an open porosity of 99% as the shape-stabilizing matrix. Its three-dimensional interconnected porous structure has high adsorption capacity and elastic toughness. Through vacuum adsorption, the gel-state material is loaded to form a strong physical support, avoiding dimensional shrinkage and deformation after long-term cycling, and ensuring fit with the human body. At the microscopic level, a dense three-dimensional gel network is formed by cross-linking with a thickening and shaping agent, which strongly locks salt ions and water molecules, inhibiting salt-water stratification from the source. The two work synergistically to achieve "external morphological stability + internal component uniformity," maintaining the gel state without flowing even if the packaging bag is damaged. At the same time, microencapsulated reversible thermochromic pigment can be optionally added to innovatively achieve integrated thermal management and visual status indication. The color change intuitively reflects the cold storage / cooling status, avoiding ineffective wearing, improving usage efficiency and safety, highlighting the functional integration innovation of this invention. Detailed Implementation

[0016] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Example 1

[0018] This invention provides a composite phase change material for cooling equipment used in high-temperature operations, comprising the following components in parts by weight: 88 parts of a main energy storage agent, 3 parts of a nucleating agent, 4 parts of a thickening and shaping agent, 2 parts of a thermal conductivity enhancer, 3 parts of deionized water, and a shape-stabilizing matrix; the main energy storage agent is sodium sulfate decahydrate and potassium chloride, with a mass ratio of sodium sulfate decahydrate to potassium chloride of 80:8; the nucleating agent is a mixture of borax and nano-titanium dioxide; the thickening and shaping agent is a compound of sodium polyacrylate and sodium carboxymethyl cellulose; and the thermal conductivity enhancer is a composition of graphene and expanded graphite.

[0019] The main energy storage agent is modified by eutectic modification of sodium sulfate decahydrate with potassium chloride / ammonium chloride, regulating the phase change temperature to the human comfort zone of 21-25℃, avoiding cold shock and condensation problems. Furthermore, the main component is a non-flammable inorganic salt, suitable for high-temperature spark operation scenarios. The nucleating agent provides ample heterogeneous nucleation sites, significantly reducing supercooling. The thickening and shaping agent constructs a three-dimensional network, combined with the porous loading of hydrophilic melamine foam, effectively preventing phase separation and leakage, maintaining long-term shape stability. The thermal conductivity enhancer improves the thermal conductivity coefficient, and combined with the high latent heat characteristics of sodium sulfate decahydrate, ensures long cooling duration and fast heat absorption response. Optional thermosensitive color-changing materials enable visualization of the cold storage / release state, avoiding ineffective wear and improving safety and efficiency. The synergistic effect of all components achieves the core advantages of suitable material temperature, high latent heat, good thermal conductivity, no supercooling, stable cycle, stable shape, and safe, non-flammable operation.

[0020] A method for preparing a composite phase change material for high-temperature cooling equipment includes the following steps: Step 1: Preparation of eutectic salt Weigh each component according to the mass fraction: main energy storage agent, nucleating agent, thickening and shaping agent, thermal conductivity enhancer, and deionized water; optionally, weigh the thermosensitive color-changing material; prepare hydrophilic melamine foam as a shape-stabilizing matrix; Add the weighed sodium sulfate decahydrate and temperature regulator to deionized water, and stir and mix for 30-60 minutes under constant temperature conditions of 40-50℃ water bath until completely dissolved to form a transparent and uniform eutectic salt solution. Step 2: Suppressing Undercooling Slowly add the ground nucleating agent to the eutectic salt solution obtained in step one, maintain the temperature and disperse by high-speed shearing and stirring; Step 3: Thermal conductivity and functional modification First, add a thermal conductivity enhancer and a thermochromic material to the solution obtained in step two, and sonicate for 10-15 minutes. Then, add a thickening and shaping agent, reduce the stirring speed to 200-300 rpm, and stir until the mixture presents a uniform viscous gel and no flowing liquid is separated. Then, impregnate the hydrophilic melamine foam into the gel, adsorb and load it under vacuum, and scrape off the excess gel on the surface after taking it out. Step 4: Shaping and Packaging After vacuum degassing of the loaded gel phase change material in step three, it is packed into a TPU or aluminum-plastic composite film bag and heat-sealed to obtain the finished product.

[0021] First, a uniform eutectic salt solution is formed by stirring in a 40-50℃ water bath to ensure precise control of the phase change temperature. Then, high-speed shear stirring ensures uniform dispersion of the nucleating agent and effectively suppresses supercooling. The thermal conductivity enhancer and thickening and shaping agent are processed stepwise to build an efficient thermal conductivity network and form a stable gel structure. Combined with vacuum adsorption, melamine foam is fully loaded. Hydrophilic melamine foam is used as the matrix material, and the phase change material is loaded through a porous structure to maintain long-term overall shape stability. Finally, vacuum degassing and hot-press sealing further prevent leakage. The overall process achieves synergistic integration of various functional components, ensuring stable product performance. The process is clear and operable, which is conducive to large-scale preparation.

[0022] In step one, the stirring rate is 500-800 rpm. During the stirring process, the transparency of the solution is continuously monitored until there are no visible particles and the refractive index is uniform, ensuring that the sodium sulfate decahydrate and the temperature regulator are completely eutectic fused.

[0023] A stirring rate of 500-800 rpm can promote the full dissolution of sodium sulfate decahydrate and temperature regulator. Continuous monitoring of transparency can ensure that the solution is free of visible particles and has a uniform refractive index, ensuring complete eutectic fusion of the two. This allows for precise control of the phase transition temperature to the target range of about 23°C, laying the foundation for the material to achieve a comfortable and effective cooling effect.

[0024] In step two, the particle size of the nucleating agent after grinding is no greater than 5 μm, ensuring that it is uniformly dispersed in the eutectic salt solution and provides sufficient heterogeneous nucleation sites.

[0025] The nucleating agent has a particle size of no more than 5 μm, which can prevent agglomeration and uniformly disperse in the eutectic salt solution, providing sufficient heterogeneous nucleation sites, significantly reducing the undercooling of the eutectic salt, ensuring that the material can quickly and naturally re-crystallize after leaving the high-temperature environment, and improving the reusability and cycle stability of the material.

[0026] In step two, the stirring speed is 800-1000 rpm and the stirring time is 15 minutes.

[0027] High-speed shearing and stirring at 800-1000 rpm and a stirring time of 15 minutes ensure that the nucleating agent after grinding is fully dispersed in the eutectic salt solution, ensuring full contact between the nucleating agent and the solution, avoiding local uneven concentration, maximizing the nucleation effect, effectively reducing supercooling, and ensuring that the material maintains stable performance during multiple heat storage and release cycles.

[0028] In step one, the thermochromic material is a microencapsulated reversible thermochromic paste with a color-changing temperature of 23±2℃.

[0029] By introducing a trace amount of thermochromic material, the "thermal management function" and "visual status indication function" are integrated into a single material without affecting the core functions. Under non-transparent encapsulation, the status is visualized, preventing invalid wearing or premature replacement, thereby improving the safety and efficiency of the equipment.

[0030] Example 2

[0031] This invention provides a composite phase change material for cooling equipment used in high-temperature operations, comprising the following components in parts by weight: 83 parts of a main energy storage agent, 3 parts of a nucleating agent, 4 parts of a thickening and shaping agent, 5 parts of a thermal conductivity enhancer, 5 parts of deionized water, and a shape-stabilizing matrix; the main energy storage agent is sodium sulfate decahydrate and potassium chloride, with a mass ratio of sodium sulfate decahydrate to potassium chloride of 75:8; the nucleating agent is a mixture of borax and nano-titanium dioxide; the thickening and shaping agent is a compound of sodium polyacrylate and sodium carboxymethyl cellulose; and the thermal conductivity enhancer is a composition of graphene and expanded graphite.

[0032] The main energy storage agent is modified by eutectic modification of sodium sulfate decahydrate with potassium chloride / ammonium chloride, regulating the phase change temperature to the human comfort zone of 21-25℃, avoiding cold shock and condensation problems. Furthermore, the main component is a non-flammable inorganic salt, suitable for high-temperature spark operation scenarios. The nucleating agent provides ample heterogeneous nucleation sites, significantly reducing supercooling. The thickening and shaping agent constructs a three-dimensional network, combined with the porous loading of hydrophilic melamine foam, effectively preventing phase separation and leakage, maintaining long-term shape stability. The thermal conductivity enhancer improves the thermal conductivity coefficient, and combined with the high latent heat characteristics of sodium sulfate decahydrate, ensures long cooling duration and fast heat absorption response. Optional thermosensitive color-changing materials enable visualization of the cold storage / release state, avoiding ineffective wear and improving safety and efficiency. The synergistic effect of all components achieves the core advantages of suitable material temperature, high latent heat, good thermal conductivity, no supercooling, stable cycling, stable shape, and safe, non-flammable properties.

[0033] A method for preparing a composite phase change material for high-temperature cooling equipment includes the following steps: Step 1: Preparation of eutectic salt: Weigh each component according to the mass fraction: main energy storage agent, nucleating agent, thickening and shaping agent, thermal conductivity enhancer, and deionized water; optionally, weigh the thermosensitive color-changing material; prepare hydrophilic melamine foam as a shape-stabilizing matrix; Add the weighed sodium sulfate decahydrate and temperature regulator to deionized water, and stir and mix for 30-60 minutes under constant temperature conditions of 40-50℃ water bath until completely dissolved to form a transparent and uniform eutectic salt solution. Step 2: Suppressing Undercooling Slowly add the ground nucleating agent to the eutectic salt solution obtained in step one, maintain the temperature and disperse by high-speed shearing and stirring; Step 3: Thermal conductivity and functional modification First, add a thermal conductivity enhancer and a thermochromic material to the solution obtained in step two, and sonicate for 10-15 minutes. Then, add a thickening and shaping agent, reduce the stirring speed to 200-300 rpm, and stir until the mixture presents a uniform viscous gel and no flowing liquid is separated. Then, impregnate the hydrophilic melamine foam into the gel, adsorb and load it under vacuum, and scrape off the excess gel on the surface after taking it out. Step 4: Shaping and Packaging After vacuum degassing of the loaded gel phase change material in step three, it is packed into a TPU or aluminum-plastic composite film bag and heat-sealed to obtain the finished product.

[0034] First, a uniform eutectic salt solution is formed by stirring in a 40-50℃ water bath to ensure precise control of the phase change temperature. Then, high-speed shear stirring ensures uniform dispersion of the nucleating agent and effectively suppresses supercooling. The thermal conductivity enhancer and thickening and shaping agent are processed stepwise to build an efficient thermal conductivity network and form a stable gel structure. Combined with vacuum adsorption, melamine foam is fully loaded. Hydrophilic melamine foam is used as the matrix material, and the phase change material is loaded through a porous structure to maintain long-term overall shape stability. Finally, vacuum degassing and hot-press sealing further prevent leakage. The overall process achieves synergistic integration of various functional components, ensuring stable product performance. The process is clear and operable, which is conducive to large-scale preparation.

[0035] In step one, the stirring rate is 500-800 rpm. During the stirring process, the transparency of the solution is continuously monitored until there are no visible particles and the refractive index is uniform, ensuring that the sodium sulfate decahydrate and the temperature regulator are completely eutectic fused.

[0036] A stirring rate of 500-800 rpm can promote the full dissolution of sodium sulfate decahydrate and temperature regulator. Continuous monitoring of transparency can ensure that the solution is free of visible particles and has a uniform refractive index, ensuring complete eutectic fusion of the two. This allows for precise control of the phase transition temperature to the target range of about 23°C, laying the foundation for the material to achieve a comfortable and effective cooling effect.

[0037] In step two, the particle size of the nucleating agent after grinding is no greater than 5 μm, ensuring that it is uniformly dispersed in the eutectic salt solution and provides sufficient heterogeneous nucleation sites.

[0038] The nucleating agent has a particle size of no more than 5 μm, which can prevent agglomeration and uniformly disperse in the eutectic salt solution, providing sufficient heterogeneous nucleation sites, significantly reducing the supercooling of the eutectic salt, ensuring that the material can quickly and naturally re-crystallize after leaving the high-temperature environment, and improving the reusability and cycle stability of the material.

[0039] In step two, the stirring speed is 800-1000 rpm and the stirring time is 15 minutes.

[0040] High-speed shearing and stirring at 800-1000 rpm and a stirring time of 15 minutes ensure that the nucleating agent after grinding is fully dispersed in the eutectic salt solution, ensuring full contact between the nucleating agent and the solution, avoiding local uneven concentration, maximizing the nucleation effect, effectively reducing supercooling, and ensuring that the material maintains stable performance during multiple heat storage and release cycles.

[0041] In step one, the thermochromic material is a microencapsulated reversible thermochromic paste with a color-changing temperature of 23±2℃.

[0042] By introducing a trace amount of thermochromic material, the "thermal management function" and "visual status indication function" are integrated into a single material without affecting the core functions. Under non-transparent encapsulation, the status is visualized, preventing invalid wearing or premature replacement, thereby improving the safety and efficiency of the equipment.

[0043] Example 3

[0044] This invention provides a composite phase change material for cooling equipment used in high-temperature operations, comprising the following components in parts by weight: 88 parts of main energy storage agent, 3 parts of nucleating agent, 4 parts of thickening and shaping agent, 2 parts of thermal conductivity enhancer, and 3 parts of deionized water; the main energy storage agent is sodium sulfate decahydrate and potassium chloride, with a mass ratio of sodium sulfate decahydrate to potassium chloride of 80:8; the nucleating agent is a mixture of borax and nano-titanium dioxide; the thickening and shaping agent is a compound of sodium polyacrylate and sodium carboxymethyl cellulose; the thermal conductivity enhancer is a composition of graphene and expanded graphite; the preparation method is the same as in Example 1, except that in step three, after the solution is stirred until the mixture presents a uniform viscous gel and no flowing liquid precipitates, it is not necessary to impregnate the hydrophilic melamine foam into the gel.

[0045] Comparative Example 1

[0046] This invention provides a comparative example of a composite phase change material for cooling equipment used in high-temperature operations. The preparation method is the same as in Example 1, comprising the following components in parts by weight: 88 parts of a main energy storage agent, 4 parts of a thickening and shaping agent, 2 parts of a thermal conductivity enhancer, 6 parts of deionized water, and a shape-stabilizing matrix; the main energy storage agent is sodium sulfate decahydrate and potassium chloride, with a mass ratio of sodium sulfate decahydrate to potassium chloride of 80:8; the thickening and shaping agent is a compound of sodium polyacrylate and sodium carboxymethyl cellulose; and the thermal conductivity enhancer is a composition of graphene and expanded graphite.

[0047] Comparative Example 2

[0048] This invention provides a comparative example of a composite phase change material for cooling equipment used in high-temperature operations. The preparation method is the same as in Example 1, comprising the following components in parts by weight: 88 parts of main energy storage agent, 3 parts of nucleating agent, 0 parts of thickening and shaping agent, 2 parts of thermal conductivity enhancer, 7 parts of deionized water, and a shape-stabilizing matrix; the main energy storage agent is sodium sulfate decahydrate and potassium chloride, with a mass ratio of sodium sulfate decahydrate to potassium chloride of 80:8; the nucleating agent is a mixture of borax and nano-titanium dioxide; and the thermal conductivity enhancer is a composition of graphene and expanded graphite.

[0049] Comparative Example 3

[0050] This invention provides a comparative example of a composite phase change material for cooling equipment used in high-temperature operations. The preparation method is the same as in Example 1, comprising the following components in parts by weight: 88 parts of main energy storage agent, 3 parts of nucleating agent, 4 parts of thickening and shaping agent, 2 parts of thermal conductivity enhancer, 3 parts of deionized water, and a shape-stabilizing matrix; the main energy storage agent is sodium sulfate decahydrate; the nucleating agent is a mixture of borax and nano-titanium dioxide; the thickening and shaping agent is a compound of sodium polyacrylate and sodium carboxymethyl cellulose; and the thermal conductivity enhancer is a composition of graphene and expanded graphite.

[0051] Performance tests were conducted using various embodiments and comparative examples, and the results are shown in the table below:

[0052] As can be seen from the table above, except for Comparative Example 3, the phase transition temperatures of the other examples and comparative examples are all suitable for human contact. Example 2 has a slightly lower latent heat due to the higher amount of graphite added. Comparative Example 1 exhibits severe supercooling and is difficult to crystallize naturally. Example 2 has the fastest heat absorption rate. Comparative Example 2's performance degrades by 50% after 10 cycles. Comparative Example 3, due to the lack of a temperature regulator, has a phase transition temperature as high as 32.3℃, far exceeding the human comfort zone of 21-25℃, and therefore cannot achieve effective cooling upon contact with the human body. All materials were in a shaped gel state. Analysis of the test results showed that Example 1 exhibited the best overall performance, with high latent heat, extremely low supercooling, and stable morphology, making it suitable as a standard filling material for high-temperature work cooling vests. Although Example 2 had a slightly lower latent heat, its thermal conductivity was excellent, making it suitable for extreme environments requiring instantaneous burst cooling (such as short-term furnace work). Example 3, lacking macroscopic support from a shape-stable matrix, deformed after 50 cycles, but without delamination or leakage, demonstrating that the micro-gel network constructed by the thickening and sizing agent can independently achieve core morphological stability. The leak-proof function further verifies the effectiveness of the "microscopic gel locking" design of this invention; its phase change temperature, latent heat, supercooling, and thermal conductivity are close to those of Example 1, and the core cooling performance is not affected, making it suitable for flexible cooling scenarios; comparing Example 1 and Example 3, it can be seen that the main role of the shape-stabilized matrix is ​​to improve the macroscopic rigidity of the material and the morphological recovery after long-term cycling, while the microscopic gel network is the core to suppress phase separation and leakage. The two work together to achieve more comprehensive stability, and the microscopic gel network alone can also meet the needs of some scenarios, reflecting the flexibility and adaptability of the formulation design; Comparative Example 1 has a very high supercooling due to the lack of nucleating agent (it needs to be cooled to 9°C to start crystallizing), which means that it cannot be restored to a solid state under normal room temperature conditions, resulting in poor practicality; Comparative Example 2 is liquid in the molten state due to the lack of thickening and shaping agent, which is prone to encapsulation damage and leakage, and severe phase separation occurs after multiple cycles, resulting in a significant decrease in latent heat value; Although Comparative Example 3 has a high latent heat and good performance in supercooling, cycle stability, and leak-proof performance, the core temperature matching defect makes it unable to meet the core requirements of high-temperature operation cooling, thus limiting its applicability.

[0053] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0054] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A composite phase change material for cooling equipment used in high-temperature operations, characterized in that, The product comprises the following components in parts by weight: 75-85 parts of main energy storage agent, 2-5 parts of nucleating agent, 3-6 parts of thickening and shaping agent, 0.2-5 parts of thermal conductivity enhancer, 5-10 parts of deionized water, 0.5-2 parts of other functional materials, and a shape-stabilizing matrix; the main energy storage agent is a mixture of sodium sulfate decahydrate and a temperature regulator, wherein the temperature regulator is potassium chloride and / or ammonium chloride; the nucleating agent is a mixture of borax and nano-titanium dioxide; the thickening and shaping agent is a compound of sodium polyacrylate and sodium carboxymethyl cellulose or fumed silica; and the thermal conductivity enhancer is graphene, or a composition of graphene with at least one of expanded graphite and carbon nanotubes.

2. The composite phase change material for high-temperature operation cooling equipment according to claim 1, characterized in that: The preferred main energy storage agent is sodium sulfate decahydrate and potassium chloride, with a mass ratio of sodium sulfate decahydrate to potassium chloride of 9:

1.

3. The composite phase change material for high-temperature operation cooling equipment according to claim 1, characterized in that: The other functional materials are added selectively, and the other functional materials are thermochromic materials.

4. The composite phase change material for high-temperature operation cooling equipment according to claim 1, characterized in that: The shape-stabilizing matrix is ​​hydrophilic melamine foam with an open porosity of 99%.

5. A method for preparing a composite phase change material for cooling equipment used in high-temperature operations, characterized in that, Includes the following steps: Step 1: Preparation of eutectic salt Weigh each component according to the mass fractions: main energy storage agent, nucleating agent, thickening and shaping agent, thermal conductivity enhancer, and deionized water; optionally, weigh the thermosensitive color-changing material; prepare hydrophilic melamine foam as a shape-stabilizing matrix; Add the weighed sodium sulfate decahydrate and temperature regulator to deionized water, and stir and mix for 30-60 minutes under constant temperature conditions of 40-50℃ water bath until completely dissolved to form a transparent and uniform eutectic salt solution. Step 2: Suppressing Undercooling Slowly add the ground nucleating agent to the eutectic salt solution obtained in step one, maintain the temperature and disperse by high-speed shearing and stirring; Step 3: Thermal conductivity and functional modification First, add a thermal conductivity enhancer and a thermochromic material to the solution obtained in step two, and sonicate for 10-15 minutes. Then, add a thickening and shaping agent, reduce the stirring speed to 200-300 rpm, and stir until the mixture presents a uniform viscous gel and no flowing liquid is separated. Then, impregnate the hydrophilic melamine foam into the gel, adsorb and load it under vacuum, and scrape off the excess gel on the surface after taking it out. Step 4: Shaping and Packaging After vacuum degassing of the loaded gel phase change material in step three, it is packed into a TPU or aluminum-plastic composite film bag and heat-sealed to obtain the finished product.

6. The method for preparing a composite phase change material for high-temperature operation cooling equipment according to claim 5, characterized in that: The stirring and mixing rate described in step one is 500-800 rpm. During the stirring process, the transparency of the solution is continuously monitored until there are no visible particles in the solution and the refractive index is uniform, ensuring that the sodium sulfate decahydrate and the temperature regulator are completely eutecticly fused.

7. The method for preparing a composite phase change material for high-temperature operation cooling equipment according to claim 5, characterized in that: The particle size of the nucleating agent after grinding in step two is no greater than 5 μm, ensuring that it is uniformly dispersed in the eutectic salt solution and provides sufficient heterogeneous nucleation sites.

8. The method for preparing a composite phase change material for high-temperature operation cooling equipment according to claim 5, characterized in that: The stirring speed in step two is 800-1000 rpm, and the stirring time is 15 minutes.

9. The method for preparing a composite phase change material for high-temperature operation cooling equipment according to claim 5, characterized in that: The thermochromic material mentioned in step one is a microencapsulated reversible thermochromic paste with a color-changing temperature of 23±2℃.

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