Fluorine-free fire-retardant two-phase coolant and preparation method and application thereof

Abstract

The application discloses a fluorine-free flame-retardant two-phase cooling liquid and a preparation method and application thereof, the cooling liquid comprises the following components in parts by mass: a base phase change agent 75-85 parts, a phase change regulator 3-15 parts, a flame-retardant stabilizer 4-8 parts and an interface modifier 2-4 parts; wherein the base phase change agent is a binary eutectic mixture formed by decanoic acid and lauric acid, the phase change regulator is a compound of isoamyl alcohol and propylene glycol, and the flame-retardant stabilizer is a compound of triphenyl phosphate and magnesium hydroxide. The cooling liquid is completely fluorine-free, and through the synergistic effect of the components, the cooling liquid has the comprehensive excellent performances of adjustable phase change temperature, high phase change latent heat, high flame-retardant grade, long-term operation stability, good material compatibility and the like. The cooling liquid is particularly suitable for an immersed liquid cooling system integrated with an intelligent control algorithm, and can be widely applied to efficient and safe heat dissipation of extreme heat load scenes such as super-high-power AI servers, energy storage batteries and high-power semiconductors.

Description

Technical Field

[0001] This invention relates to a fluorine-free flame-retardant two-phase coolant, its preparation method and application, belonging to the field of coolant preparation technology. Background Technology

[0002] Faced with the extreme heat dissipation challenges brought about by breakthroughs in the power density of electronic devices, two-phase immersion liquid cooling technology has become a core direction due to its advantage of utilizing the latent heat of phase change. However, the development of this technology is limited by the key defects of fluorinated and non-fluorinated coolants. Although fluorinated coolants are currently the mainstream high-performance medium, they are listed as a target for reduction by international conventions due to their global warming potential of thousands or tens of thousands of ppm, facing huge environmental and policy ban risks. Their complex synthesis process and scarce raw materials result in extremely high costs, reaching dozens of times that of traditional coolants, and there is also a safety hazard of thermal decomposition producing highly toxic gases. The fluorinated non-fluorinated coolants based on alcohols, hydrocarbons, and esters developed to avoid the above problems have exposed new shortcomings: alcohols generally have low latent heat of phase change and inaccurate temperature control windows; hydrocarbons have extremely low flash points, posing a risk of flammability and explosion; and esters are prone to hydrolysis, corrosion of metals, and phase separation. Most of these fluorine-free alternatives fail to meet mandatory flame-retardant standards in terms of safety. Adding halogenated flame retardants can cause secondary pollution, and long-term operation often results in problems such as boiling over, excessive phase change temperature drift, excessive latent heat decay, and poor compatibility leading to seal failure. At a deeper level, existing cooling system architectures often directly adopt designs adapted to fluorine-containing coolants, failing to adapt to the characteristics of fluorine-free media. This leads to a series of system-level defects, including insufficient natural circulation power, unstable forced circulation, lack of intelligent control algorithms, and slow safety monitoring response. Therefore, the entire field is deeply mired in multiple contradictions, making it difficult to balance environmental protection, safety, performance, cost, and system compatibility. A fundamental technological innovation that can systematically solve all these pain points is urgently needed. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a fluorine-free flame-retardant two-phase coolant, comprising the following components by mass: 75-85 parts of a basic phase change agent, 3-15 parts of a phase change modifier, 4-8 parts of a flame-retardant stabilizer, and 2-4 parts of an interface modifier; wherein the basic phase change agent is a binary eutectic mixture formed by decanoic acid and lauric acid, the phase change modifier is a compound of isoamyl alcohol and propylene glycol, and the flame-retardant stabilizer is a compound of triphenyl phosphate and magnesium hydroxide.

[0004] Preferably, the mass ratio of decanoic acid to lauric acid is 6:4-7:3; more preferably 6.5:3.5.

[0005] Preferably, the mass ratio of isoamyl alcohol to propylene glycol is 1:2 to 1:3.

[0006] Preferably, the mass ratio of triphenyl phosphate to magnesium hydroxide is 1:1.5-1:2.

[0007] Preferably, the particle size of the magnesium hydroxide is less than or equal to 5 μm.

[0008] Preferably, the interface modifier is a compound of silane coupling agent KH570 and polyethylene glycol monomethyl ether; the mass ratio of silane coupling agent KH570 to polyethylene glycol monomethyl ether is 1:1.

[0009] Preferably, the coolant has a kinematic viscosity of 3-5 mm² / s at 25°C; a phase change temperature of 35-45°C and a latent heat of phase change ≥180 kJ / kg; a flame retardant rating of UL94V-0 and an ignition point ≥300°C; a corrosion rate of the coolant on metals ≤0.003 mm / a and a swelling rate of fluororubber seals ≤3%.

[0010] This invention also provides a method for preparing the above-mentioned fluorine-free flame-retardant two-phase coolant, comprising the following steps: S1. Raw material pretreatment: vacuum drying the basic phase change agent raw material; distilling and purifying the phase change modifier raw material; pulverizing the solid component of the flame retardant stabilizer raw material and mixing it with the liquid component and part of the interface modifier for surface modification; mixing the interface modifier raw material; S2. Preparation of basic phase change agent: mixing the pretreated basic phase change agent raw material in proportion, heating and stirring to form a homogeneous eutectic mixture, and then cooling; S3. Composite modification: heating and melting the basic phase change agent obtained in step S2, sequentially adding the pretreated phase change modifier, flame retardant stabilizer and interface modifier, and stirring in stages to uniformly disperse each component; S4. Degassing treatment: degassing the mixture obtained in step S3 under heating and vacuum conditions; S5. Filtration: filtering the degassed liquid to obtain the finished coolant.

[0011] Preferably, in step S1, the conditions for vacuum drying of the basic phase change agent raw material are: temperature 75-80℃, vacuum degree -0.09MPa, and time 1.5-2h; in step S2, the heating temperature is 70-80℃, the stirring rate is 400-500rpm, and the time is 30-40min.

[0012] Preferably, the isoamyl alcohol and propylene glycol obtained by distillation and purification of the phase change modifier raw material have a purity of ≥99.5%; the surface modification conditions of the flame retardant stabilizer raw material are as follows: magnesium hydroxide pulverized to a particle size ≤5μm is mixed with triphenyl phosphate and 1-2% of the total mass of the two silane coupling agent KH570, and treated at 60-65℃ and a stirring rate of 450-500rpm for 20min; the interface modifier raw material is silane coupling agent KH570 and polyethylene glycol monomethyl ether, mixed at a mass ratio of 1:1.

[0013] Preferably, in step S3, the basic phase change agent is heated to 50-60℃ to melt; after adding the phase change modifier, it is stirred at a stirring rate of 500-600 rpm for 15-20 min; after adding the flame retardant stabilizer, the stirring rate is increased to 800-1000 rpm and stirred for 25-30 min; after adding the interface modifier, the stirring rate is maintained at 800-1000 rpm and stirring is continued for 30-35 min; in step S4, the degassing treatment temperature is 65-75℃, the vacuum degree is -0.09--0.08 MPa, the stirring rate is 300-350 rpm, and the time is 30-35 min.

[0014] Preferably, in step S5, a ceramic filter membrane with a precision of 1 μm is used for filtration.

[0015] The present invention also provides the application of the above-mentioned fluorine-free flame-retardant two-phase coolant in an immersion liquid cooling system.

[0016] Preferably, the immersion liquid cooling system includes a liquid cooling cabinet, a condensing unit, a circulating pump, a sensor group, a central controller, and a safety protection module; the sensor group includes at least a temperature sensor for monitoring the core temperature of the equipment and the temperature of the coolant, a liquid level sensor for monitoring the liquid level, a turbidity sensor for monitoring the dispersion stability of the coolant, and a flame retardant monitoring sensor for monitoring the risk of combustion; the central controller integrates PID control algorithm and fuzzy control algorithm to dynamically adjust the flow rate of the circulating pump and the condensing temperature of the condensing unit based on the sensor data.

[0017] Preferably, when the heat load is ≤300W / cm² 2 When the heat load is 300-700 W / cm², the controller starts the circulating pump, maintaining a flow rate of 0.3-0.4 m / s and a condensing temperature of 30℃. 2 When the heat load exceeds 700W / cm², the controller shuts off the circulation pump, switches to natural circulation mode, and adjusts the condensing temperature to 27-28℃ according to the phase change rate; 2 When this happens, the controller will lower the condensation temperature to 25-26℃ and activate the backup cooling circuit.

[0018] Preferably, the application scenarios include heat dissipation of ultra-high power AI servers, energy storage battery modules, or high-power semiconductor devices.

[0019] The beneficial effects of this invention are:

[0020] The fluorine-free flame-retardant two-phase coolant, its preparation method, and its application provided by this invention achieve multiple advancements by constructing a quaternary synergistic system of a basic phase change agent, a phase change modifier, a flame-retardant stabilizer, and an interface modifier, along with an optimized preparation process and intelligent application system. Firstly, in terms of environmental friendliness, it completely eliminates fluorine-containing compounds, has a high biodegradability rate for raw materials, and a GWP value close to zero, fully complying with global green development trends and stringent environmental regulations. Secondly, in terms of heat dissipation performance, the decanoic acid-lauric acid eutectic system provides high latent heat of phase change and precisely controllable phase change temperature, perfectly matching the operating range of electronic devices. Its heat dissipation efficiency is more than 50% higher than existing fluorine-free products, effectively handling temperatures exceeding 1000 W / cm². 2 Third, in terms of safety and stability, the combination of triphenyl phosphate and magnesium hydroxide achieves halogen-free, highly efficient, and synergistic flame retardancy, enabling the coolant to reach the highest UL94V-0 flame retardant standard, with an ignition point exceeding 300℃. Simultaneously, the interface modifier effectively inhibits boiling and phase separation, ensuring the stability of the phase change temperature and long service life under long-term operation, and exhibiting excellent compatibility with metals and sealing materials. Fourth, in terms of economy, the raw materials are all common industrial products, with costs only 30-50% of fluorinated coolants, and the long service life significantly reduces maintenance costs. Finally, the accompanying intelligent liquid cooling system, through multi-sensor fusion and advanced control algorithms, achieves dynamic and precise matching between heat dissipation capacity and heat load. The system is highly energy efficient and responds quickly, providing an efficient, safe, reliable, and economical end-to-end heat dissipation solution for ultra-high power density equipment. Attached Figure Description

[0021] Figure 1 Photographs of the sample prepared in Example 1 of this invention;

[0022] Figure 2 Photograph of the fluorine-containing coolant sample for Comparative Example 1. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0025] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the experimental materials used in the following examples are all purchased from commercial channels.

[0026] Example 1

[0027] This embodiment provides a fluorine-free flame-retardant two-phase coolant, the specific formula of which is as follows by mass percentage: 80% decanoic acid-lauric acid binary eutectic mixture (mass ratio 6.5:3.5), 3% isoamyl alcohol (purity 99.6%), 6% propylene glycol (purity 99.5%), 3% triphenyl phosphate (purity 99.8%), 4% magnesium hydroxide (particle size ≤5μm), 2% silane coupling agent KH570 (purity 99.7%), and 2% polyethylene glycol monomethyl ether (molecular weight 200). The preparation method includes the following specific steps: Step 1, raw material pretreatment: Decanoic acid (Hubei Keward Chemical Co., Ltd., Keward CAS334-48-5, purity 99%, packaging specification 25KG / bag, appearance: white crystals, with unpleasant odor, industrial grade, national standard, core physicochemical parameters: boiling point: 270℃, density: 0.9g / cm³ (under normal conditions), solubility: insoluble in water, soluble in most organic solvents) 52kg and lauric acid (analytical grade, Shandong Jinyueyuan New Material Co., Ltd.) Lauric acid (99% purity, acid, packaged in 25kg bags, brand "Domestic / Malaysian Coconut Tree") 28kg were placed in a vacuum drying oven and dried at 80℃ and -0.09MPa for 2 hours to remove moisture; industrial grade isoamyl alcohol (purity ≥99.0%) and propylene glycol (purity ≥99.0%) were purified by distillation, and fractions with purity ≥99.6% and ≥99.5% were collected for later use; 4kg of magnesium hydroxide (industrial grade, particle size D50 approximately 10μm, Shandong Yousuo Chemical Technology Co., Ltd.) was added The mixture was pulverized in a high-speed pulverizer until it passed through a 5μm sieve. Then, it was added to a stirred tank along with 3kg of triphenyl phosphate (industrial grade, purity ≥99.5%, Jiangsu Yake Technology Co., Ltd.) and 0.07kg (1% of the total mass of both) of silane coupling agent KH570 (analytical grade, Nanjing Xiangfei Chemical Research Institute). The mixture was treated at 60℃ and 500rpm for 20 minutes to complete surface modification. Separately, 1.93kg of KH570 and 2kg of polyethylene glycol monomethyl ether (chemically pure, molecular weight 200, above...) were added... (Haimaikelin Biochemical Technology Co., Ltd.) The mixture is manually stirred in a beaker until homogeneous and set aside. The second step is the preparation of the basic phase change agent: 52 kg of pretreated decanoic acid and 28 kg of lauric acid are added to a jacketed, heated stainless steel reactor. Heating is turned on to raise the material temperature to 75°C. Stirring is then started and controlled at 500 rpm, continuing for 35 minutes until the mixture in the reactor becomes completely homogeneous and transparent. Heating is then turned off, and the reactor is allowed to cool naturally to room temperature, yielding a white, waxy solid. Gas chromatography analysis shows a purity of 99.5%.Step 3, Composite Modification: 80 kg of the waxy basic phase change agent obtained in Step 2 is added back to the reactor. The jacket heating is turned on, and the material temperature is raised to 55℃ to completely melt it into a liquid state. First, 3 kg of purified isoamyl alcohol and 6 kg of purified propylene glycol are added, and the stirring speed is set to 600 rpm, and stirring is continued for 15 min. Then, the pretreated flame retardant stabilizer is added, and the stirring speed is rapidly increased to 900 rpm. The particles are dispersed using high-speed shear force, and strong stirring is continued for 30 min. Finally, 2 kg of premixed interface modifier is added, and the stirring speed is maintained at 900 rpm, and stirring is continued for 30 min. Step 4, Degassing Treatment: The reactor temperature is adjusted to 70℃, the vacuum pump is turned on, and the vacuum degree inside the reactor is controlled at -0.085 MPa. At the same time, the stirring speed is reduced to 300 rpm to avoid generating new bubbles. Under these conditions, degassing treatment is carried out for 30 min. Step 5, Filtration and Finished Product Testing: The degassed coolant is passed through a filter equipped with a ceramic filter membrane with a pore size of 1μm and filtered at a filtration pressure of 0.4MPa with an average filtration flow rate of 45L / h; the clear liquid obtained after filtration is the finished coolant.

[0028] Figure 1 The sample prepared in this embodiment is a homogeneous, semi-transparent, slightly milky-white liquid, free of visible particles or suspended matter, with good fluidity, and shows no obvious stratification or sedimentation after standing. This coolant was applied to an immersion liquid-cooled cabinet designed for an AI server. The cabinet dimensions are 2000mm × 1000mm × 1200mm. The coolant was injected to 65% of the cabinet height, ensuring the server's CPU / GPU was completely submerged. The system is equipped with a finned condenser (condensation area 2.5m²), a variable frequency magnetic drive pump (600W power), a PT1000 temperature sensor, a capacitive level gauge, a turbidity meter, and a smoke sensor, all centrally controlled by a PLC controller integrating PID and fuzzy control algorithms. In a test simulating a 1200W / cm² heat load, the system automatically operated in high-load mode, with the condensation temperature dropping to 25℃ and the CPU core temperature stabilizing at 42℃, without any boiling over.

[0029] Example 2

[0030] This embodiment provides a fluorine-free two-phase coolant with high flame retardant performance. Its specific formula, by mass percentage, is as follows: 78% decanoic acid-lauric acid binary eutectic mixture (mass ratio 6.5:3.5), 2.5% isoamyl alcohol (purity 99.5%), 5% propylene glycol (purity 99.5%), 4% triphenyl phosphate (purity 99.8%), 5% magnesium hydroxide (particle size ≤5μm), 2.5% silane coupling agent KH570 (purity 99.7%), and 3% polyethylene glycol monomethyl ether (molecular weight 200). The preparation method includes the following specific steps: First, raw material pretreatment: 50.7 kg of decanoic acid and 27.3 kg of lauric acid were placed in a vacuum drying oven and dried at 80℃ and -0.09 MPa for 2 hours to remove moisture; industrial grade isoamyl alcohol and propylene glycol were purified by distillation column, and fractions with a purity ≥99.5% were collected for later use; 5 kg of magnesium hydroxide was put into a high-speed pulverizer and pulverized until it all passed through a 5 μm sieve, and then added to a stirred tank along with 4 kg of triphenyl phosphate and 0.09 kg (i.e., 1% of the total mass of the two) of silane coupling agent KH570, and treated at 60℃ and 500 rpm for 20 minutes to complete the surface modification; 2.41 kg of KH570 and 3 kg of polyethylene glycol monomethyl ether were manually stirred in a beaker until they were mixed evenly for later use. The second step is to prepare the basic phase change agent: 50.7 kg of pretreated decanoic acid and 27.3 kg of lauric acid are put into a stainless steel reactor with a jacketed heating system. The heating is turned on to raise the temperature of the material to 75°C. Stirring is started and the speed is controlled at 500 rpm. Stirring is continued for 35 minutes until the mixture in the reactor becomes completely homogeneous and transparent. The heating is turned off and the reactor is allowed to cool naturally to room temperature to obtain a white waxy solid. The purity is 99.4% as determined by gas chromatography. Step 3, Composite Modification: 78 kg of the waxy basic phase change agent obtained in Step 2 was added back to the reactor. The jacket heating was turned on, and the material temperature was raised to 55℃ to completely melt it into a liquid state. First, 2.5 kg of purified isoamyl alcohol and 5 kg of purified propylene glycol were added, and the stirring speed was set to 600 rpm for 15 min. Then, the pretreated flame retardant stabilizer was added, and the stirring speed was rapidly increased to 950 rpm to disperse the particles using high-speed shear force, and strong stirring was continued for 35 min. Finally, 2.5 kg of premixed interface modifier was added, and the stirring speed was maintained at 950 rpm for 30 min. Step 4, Degassing Treatment: The reactor temperature was adjusted to 70℃, the vacuum pump was turned on, and the vacuum degree inside the reactor was controlled at -0.085 MPa. At the same time, the stirring speed was reduced to 300 rpm to avoid generating new bubbles. Under these conditions, degassing treatment was carried out for 30 min. Step 5, Filtration and Finished Product Testing: The degassed coolant is passed through a filter equipped with a ceramic filter membrane with a pore size of 1μm and filtered at a filtration pressure of 0.4MPa with an average filtration flow rate of 40L / h; the clear liquid obtained after filtration is the finished coolant.

[0031] Example 3

[0032] This embodiment provides a fluorine-free two-phase coolant suitable for slightly lower operating temperature scenarios. Its specific formula, by mass percentage, is as follows: 85% decanoic acid-lauric acid binary eutectic mixture (mass ratio 6:4), 4% isoamyl alcohol (purity 99.5%), 6% propylene glycol (purity 99.5%), 2% triphenyl phosphate (purity 99.8%), 2% magnesium hydroxide (particle size ≤5μm), 0.5% silane coupling agent KH570 (purity 99.7%), and 0.5% polyethylene glycol monomethyl ether (molecular weight 200). The preparation method includes the following specific steps: First, raw material pretreatment: 51 kg of decanoic acid and 34 kg of lauric acid are placed in a vacuum drying oven and dried at 80℃ and -0.09 MPa for 2 hours to remove moisture; industrial grade isoamyl alcohol and propylene glycol are purified by distillation column, and fractions with a purity ≥99.5% are collected for later use; 2 kg of magnesium hydroxide is added to a high-speed pulverizer and pulverized until it passes through a 5 μm sieve, and then added to a stirred tank along with 2 kg of triphenyl phosphate and 0.04 kg (i.e., 1% of the total mass of the two) of silane coupling agent KH570, and treated at 60℃ and 500 rpm for 20 minutes to complete the surface modification; separately, 0.46 kg of KH570 and 0.5 kg of polyethylene glycol monomethyl ether are manually stirred in a beaker until they are mixed evenly for later use. The second step is to prepare the basic phase change agent: 51 kg of pretreated decanoic acid and 34 kg of lauric acid are put into a stainless steel reactor with a jacketed heating system. The heating is turned on to raise the temperature of the material to 75°C. Stirring is started and the speed is controlled at 500 rpm. Stirring is continued for 35 minutes until the mixture in the reactor becomes completely homogeneous and transparent. The heating is turned off and the reactor is allowed to cool naturally to room temperature to obtain a white waxy solid. The purity is 99.3% as determined by gas chromatography. Step 3, Composite Modification: 85 kg of the waxy basic phase change agent obtained in Step 2 is added back to the reactor. The jacket heating is turned on, and the material temperature is raised to 55℃ to completely melt it into a liquid state. First, 4 kg of purified isoamyl alcohol and 6 kg of purified propylene glycol are added, and the stirring speed is set to 600 rpm, and stirring is continued for 15 min. Then, the pretreated flame retardant stabilizer is added, and the stirring speed is rapidly increased to 850 rpm. The particles are dispersed using high-speed shear force, and strong stirring is continued for 30 min. Finally, 0.5 kg of premixed interface modifier is added, and the stirring speed is maintained at 850 rpm, and stirring is continued for 20 min. Step 4, Degassing Treatment: The reactor temperature is adjusted to 70℃, the vacuum pump is turned on, and the vacuum degree inside the reactor is controlled at -0.085 MPa. At the same time, the stirring speed is reduced to 300 rpm to avoid generating new bubbles. Under these conditions, degassing treatment is carried out for 30 min. Step 5, Filtration and Finished Product Testing: The degassed coolant is passed through a filter equipped with a ceramic filter membrane with a pore size of 1μm and filtered at a filtration pressure of 0.4MPa with an average filtration flow rate of 50L / h; the clear liquid obtained after filtration is the finished coolant.

[0033] Comparative Example 1 (Fluorine-containing coolant)

[0034] This comparative example uses a commercially available fluorinated two-phase coolant. It was purchased directly without any preparation and used for performance comparison testing. This coolant is a transparent, colorless liquid with a kinematic viscosity of approximately 0.65 mmHg at 25°C. 2 It has a phase change temperature of approximately 56°C and a latent heat of phase change of approximately 88 kJ / kg. It is non-flammable and has excellent compatibility with metal and rubber materials, but its global warming potential is as high as 9100, and it is also very expensive.

[0035] Comparative Example 2 (Differences in the basic phase change agent formulation)

[0036] The comparative coolant formulation, by mass percentage, is as follows: 80% decanoic acid-lauric acid mixture (mass ratio 8:2), 3% isoamyl alcohol (purity 99.5%), 6% propylene glycol (purity 99.5%), 3% triphenyl phosphate (purity 99.8%), 4% magnesium hydroxide (particle size ≤5μm), 2% silane coupling agent KH570 (purity 99.7%), and 2% polyethylene glycol monomethyl ether (molecular weight 200). The preparation method includes the following specific steps: Step 1, raw material pretreatment: 64 kg of decanoic acid and 16 kg of lauric acid are placed in a vacuum drying oven and dried at 80℃ and -0.09 MPa for 2 hours; industrial-grade isoamyl alcohol and propylene glycol are purified to a purity ≥99.5% by a distillation column; 4 kg of magnesium hydroxide is pulverized to a particle size ≤5 μm and then surface-modified by stirring with 3 kg of triphenyl phosphate and 0.07 kg of KH570 at 60℃ and 500 rpm for 20 minutes; 1.93 kg of KH570 is mixed with 2 kg of polyethylene glycol monomethyl ether for later use. Step 2, preparation of the basic phase change agent: 64 kg of decanoic acid and 16 kg of lauric acid are stirred in a reaction vessel at 75℃ and 500 rpm for 35 minutes, and then cooled to obtain a eutectic mixture. Step 3, Composite Modification: Melt 80 kg of the base phase change agent at 55℃, then add 3 kg of isoamyl alcohol, 6 kg of propylene glycol (600 rpm, 15 min), pretreated flame retardant stabilizer (900 rpm, 30 min), and 2 kg of interface modifier (900 rpm, 30 min) sequentially. Step 4, Degassing Treatment: Degas for 30 min at 70℃, -0.085 MPa, and 300 rpm. Step 5, Filtration: Filter through a 1 μm ceramic filter membrane to obtain the finished coolant.

[0037] Comparative Example 3 (Differences in Flame Retardant Stabilizers)

[0038] The coolant formulation of this comparative example, by mass percentage, is: 80% decanoic acid-lauric acid binary eutectic mixture (mass ratio 6.5:3.5), 3% isoamyl alcohol (purity 99.5%), 6% propylene glycol (purity 99.5%), 2% silane coupling agent KH570 (purity 99.7%), and 2% polyethylene glycol monomethyl ether (molecular weight 200). The preparation method includes the following specific steps: Step 1, raw material pretreatment: 56.55 kg of decanoic acid and 30.45 kg of lauric acid are vacuum dried at 80℃ for 2 hours; isoamyl alcohol and propylene glycol are purified to a purity ≥99.5%; 2 kg of KH570 and 2 kg of polyethylene glycol monomethyl ether are mixed for later use. (This comparative example does not include a flame retardant stabilizer pretreatment step). The second step is the preparation of the basic phase change agent: 56.55 kg of decanoic acid and 30.45 kg of lauric acid are stirred in a reactor at 75°C and 500 rpm for 35 min, and then cooled to obtain a eutectic mixture. The third step is composite modification: 87 kg of the basic phase change agent is melted at 55°C, and 3 kg of isoamyl alcohol, 6 kg of propylene glycol (600 rpm, 15 min), (skipping the step of adding flame retardant stabilizer), and 2 kg of interface modifier (900 rpm, 30 min) are added sequentially. The fourth step is degassing: degassing is performed at 70°C, -0.085 MPa, and 300 rpm for 30 min. The fifth step is filtration: the product coolant is obtained by filtration through a 1 μm ceramic filter membrane.

[0039] Comparative Example 4 (Differences with interface modifier KH570)

[0040] The comparative example coolant formulation, by mass percentage, is as follows: 82% decanoic acid-lauric acid binary eutectic mixture (mass ratio 6.5:3.5), 3% isoamyl alcohol (purity 99.5%), 6% propylene glycol (purity 99.5%), 3% triphenyl phosphate (purity 99.8%), 4% magnesium hydroxide (particle size ≤5μm), and 2% polyethylene glycol monomethyl ether (molecular weight 200). The preparation method includes the following specific steps: Step 1, raw material pretreatment: 53.3 kg of decanoic acid and 28.7 kg of lauric acid were vacuum dried at 80℃ for 2 hours; isoamyl alcohol and propylene glycol were purified to a purity ≥99.5%; 4 kg of magnesium hydroxide was pulverized to a particle size ≤5μm and mixed with 3 kg of triphenyl phosphate (KH570 was not added for surface modification in this step); 2 kg of polyethylene glycol monomethyl ether was kept separately (without KH570 for mixing). The second step is the preparation of the basic phase change agent: 53.3 kg of decanoic acid and 28.7 kg of lauric acid are stirred in a reactor at 75°C and 500 rpm for 35 min, and then cooled to obtain a eutectic mixture. The third step is composite modification: 82 kg of the basic phase change agent is melted at 55°C, and then 3 kg of isoamyl alcohol, 6 kg of propylene glycol (600 rpm, 15 min), a flame retardant stabilizer (i.e., a simple mixture of magnesium hydroxide and triphenyl phosphate, 900 rpm, 30 min) without KH570 surface modification, and 2 kg of polyethylene glycol monomethyl ether (900 rpm, 30 min) are added sequentially. The fourth step is degassing: degassing is performed at 70°C, -0.085 MPa, and 300 rpm for 30 min. The fifth step is filtration: the product coolant is obtained by filtration through a 1 μm ceramic filter membrane.

[0041] Comparative Example 5 (Conventional CFC-free coolant system)

[0042] This comparative example uses a traditional two-phase immersion liquid cooling system designed with fluorinated coolant, using the coolant prepared in Example 1. The system is configured as follows: the liquid cooling cabinet measures 2000mm × 1000mm × 1200mm; a finned condenser (2.5m²) is installed on the top, and its cooling water circulation system is driven by only one fixed-frequency water pump, with the condenser inlet water temperature set to a constant 28℃; a switch-controlled centrifugal pump (600W) is installed at the bottom of the cabinet, and its start and stop are controlled by a temperature switch located in the middle of the cabinet, starting when the temperature at the detection point exceeds 40℃ and stopping when it is below 35℃; the sensors include only three PT100 temperature sensors, located in the middle, upper part and on a CPU simulated heat source surface of the cabinet respectively, without liquid level, turbidity and smoke sensors; the system does not have a central controller, and only realizes the start and stop control of the pump through a relay circuit, without PID or fuzzy control algorithms, without a backup cooling circuit, and the safety protection module only includes an independent audible and visual alarm, which is linked to the temperature switch over-temperature alarm point (50℃).

[0043] The samples obtained from all the above embodiments and comparative examples were tested using the following methods, and the results are shown in Table 1.

[0044] Detection method:

[0045] Phase transition temperature and latent heat: Differential scanning calorimetry (DSC) was used. 10 mg of sample was accurately weighed and sealed in an aluminum crucible, with an empty crucible used as a reference. Under a nitrogen atmosphere, the temperature was increased from 10 °C to 80 °C at a rate of 5 °C / min, and the DSC curve was recorded. The phase transition temperature was taken as the temperature at which the phase transition peak began. The latent heat of phase transition was obtained by calculating the area integral of the phase transition peak in the DSC curve; the instrument software automatically converted it to kJ / kg based on the sample mass.

[0046] Kinematic viscosity: A rotational viscometer and a constant-temperature water bath are used. The sample is poured into the measuring cup and kept at a constant temperature of 25.0±0.1℃. A suitable rotor and rotation speed are selected so that the torque percentage is between 10% and 90%. After the reading stabilizes, it is recorded. The instrument directly displays the kinematic viscosity value.

[0047] Flame retardancy rating (UL94V-0 / V-1): Prepare a standard test strip measuring 125mm × 13mm × 3mm. Suspend vertically and ignite the bottom of the test strip with a Bunsen burner (flame height 20mm) for 10 seconds. Remove the flame and record the flaming time t1. Immediately after the flame extinguishes, ignite again for 10 seconds, remove the flame, and record the second flaming time t2 and the flameless burning time. V-0 rating requirements: flaming time after each ignition ≤ 10 seconds, total flaming time (t1 + t2) ≤ 50 seconds, flameless burning time ≤ 30 seconds, and the strip must not ignite the absorbent cotton below. V-1 rating requirements are slightly more lenient.

[0048] Ignition point: The Cleveland open cup method was used. The sample was poured into the test cup up to the mark and placed on an electric furnace for heating, with the heating rate controlled. Starting at 28°C before the expected ignition point, the flame of an igniter was swept horizontally across the center of the cup opening every 2°C. The temperature at which the sample vapor was first ignited and could continue to burn for at least 5 seconds was recorded as the ignition point.

[0049] Metal corrosion rate: A polished, cleaned, and precisely weighed standard copper sheet (as required by GB / T5096) is completely immersed in a sealed corrosion test chamber containing the sample and placed in an oven at 100°C for 168 hours. The copper sheet is then removed, cleaned to remove corrosion products according to standard procedures, dried, and precisely weighed again. The corrosion rate is calculated using the formula:

[0050] W a W b The mass (g) before and after the experiment is given, and K is a constant 8.76 × 10⁻⁶. 4 D is the density of the metal (g / cm³) 3 A is the sample area (cm²) 2), where T is time (h).

[0051] Swelling rate of sealant: Weigh a standard-sized fluororubber O-ring (GB / T1690) (W0), immerse it in a sealed container containing the sample, and maintain it at 100℃ for 168 hours. Remove the O-ring, gently blot the surface liquid with filter paper, and weigh it immediately (W1). Swelling rate calculation:

[0052] .

[0053] Boiling suppression rate and phase separation rate: Boiling suppression rate was evaluated using a visual hot-stage experiment: A transparent quartz dish containing the sample was placed on a heating stage, with a miniature heating point at the bottom to simulate a hot spot, and a high-speed camera recorded the phase transition process. The number of violent, large bubble bursts (boiling) was counted out of 100 phase transition events. Boiling suppression rate = (1 - number of boiling events / 100) × 100%. Phase separation rate: After the sample was left to stand at 80℃ for 1000h and cooled to room temperature, the percentage of mass showing stratification or precipitation was observed or measured by centrifugation.

[0054] Accelerated aging and latent heat decay: The sample was sealed and placed in a 120℃ forced-air drying oven for 1000 hours (equivalent to several years of room temperature service life). The latent heat of phase change was measured by DSC before and after aging, and the decay percentage was calculated.

[0055] System PUE: On a liquid cooling system test platform, the total power consumption (PUE) of the entire cooling system (including pumps, condenser fans / water pumps, controllers, etc.) is measured. cooling ), and the power consumption of the IT equipment served (P IT PUE=(P IT +P cooling ) / P IT .

[0056] GWP and Cost: The GWP value is a weighted estimate based on the GWP values ​​of each component in the IPCC assessment report. The raw material cost is based on current commodity market quotations, discounted to 100% of the cost of Comparative Example 1 (FC-72).

[0057] Table 1 Test Results

[0058]

[0059] The test results show that the fluorine-free flame-retardant two-phase coolant provided in Examples 1-3 of this invention completely surpasses the existing technology. Compared with the fluorinated coolant in Comparative Example 1, this invention maintains a high latent heat of phase change while reducing the GWP value from 9100 to almost zero, demonstrating significant environmental advantages and a substantial reduction in raw material costs of approximately 60%. Although its ignition point and compatibility with certain materials are slightly inferior to non-flammable fluorinated liquids, it has achieved a V-0 flame retardancy rating, ensuring extremely high safety. Compared with Comparative Example 2, this invention demonstrates the crucial role of the 6:4-7:3 ratio of decanoic acid to lauric acid in precisely controlling the phase change temperature within the optimal range of 35-45℃. In Comparative Example 2, the excessively low temperature may have led to abnormal load on the condensation system. Compared with Comparative Example 3, this invention highlights the synergistic flame retardancy necessity of the triphenyl phosphate and magnesium hydroxide composite system. The absence of either component results in a reduction in the flame retardancy rating to V-1, a significant decrease in the ignition point, and an increase in safety risks. Compared with Comparative Example 4, this invention demonstrates the decisive role of KH570 in suppressing boiling over, preventing phase separation, and improving compatibility with sealing materials, reducing the swelling rate from 5.8% to 2.3%. Its absence directly leads to a significant decrease in operational stability and system reliability. All embodiments exhibit excellent long-term thermal stability, high heat dissipation efficiency, and high energy efficiency. Therefore, this invention successfully solves multiple contradictions simultaneously, including environmental protection, efficient heat dissipation, safety and stability, and cost control, through unique component synergistic design, precise preparation process, and intelligent application system.

[0060] 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.

[0061] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention. The actual application is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar methods and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A fluorine-free flame-retardant two-phase coolant, characterized in that, By mass, it includes the following components: 75-85 parts of base phase change agent, 3-15 parts of phase change modifier, 4-8 parts of flame retardant stabilizer, and 1-4 parts of interface modifier. The basic phase change agent is a binary eutectic mixture formed by decanoic acid and lauric acid; The phase change modifier is a compound of isoamyl alcohol and propylene glycol; The flame retardant stabilizer is a compound of triphenyl phosphate and magnesium hydroxide; The mass ratio of decanoic acid to lauric acid is 6:4-7:3; The interface modifier is a compound of silane coupling agent KH570 and polyethylene glycol monomethyl ether. The mass ratio of the silane coupling agent KH570 to polyethylene glycol monomethyl ether is 1:1 to 1:1.

2.

2. The fluorine-free flame-retardant two-phase coolant according to claim 1, characterized in that, The mass ratio of isoamyl alcohol to propylene glycol is 1:2 to 1:

3.

3. The fluorine-free flame-retardant two-phase coolant according to claim 1, characterized in that, The mass ratio of triphenyl phosphate to magnesium hydroxide is 1:1 to 1:

2.

4. A method for preparing a fluorine-free flame-retardant two-phase coolant according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Raw material pretreatment: Vacuum drying of the basic phase change agent raw material; distillation purification of the phase change modifier raw material; pulverization of the solid components in the flame retardant stabilizer raw material and mixing with the liquid components and some interface modifiers for surface modification; mixing of the interface modifier raw material; S2. Preparation of basic phase change agent: The pretreated basic phase change agent raw materials are mixed in proportion, heated and stirred to form a homogeneous eutectic mixture, and then cooled; S3. Composite modification: The basic phase change agent obtained in step S2 is heated and melted, and the pretreated phase change modifier, flame retardant stabilizer and interface modifier are added in sequence. The mixture is stirred in stages to make each component evenly dispersed. S4. Degassing treatment: The mixture obtained in step S3 is degassed under heating and vacuum conditions; S5. Filtration: Filter the degassed liquid to obtain the finished coolant.

5. The preparation method according to claim 4, characterized in that, In step S1, the conditions for vacuum drying of the basic phase change agent raw material are: temperature 75-80℃, vacuum degree -0.09MPa, and time 1.5-2h; the conditions for surface modification of the flame retardant stabilizer raw material are: mixing pulverized magnesium hydroxide with triphenyl phosphate and 1-2% of the total mass of the two silane coupling agent KH570, and treating it at 60-65℃ and a stirring rate of 450-500rpm for 20min.

6. The preparation method according to claim 4, characterized in that, In step S2, the heating temperature is 70-80℃, the stirring rate is 400-500 rpm, and the time is 30-40 min.

7. The preparation method according to claim 4, characterized in that, In step S3, the basic phase change agent is heated to 50-60℃ to melt; after adding the phase change modifier, it is stirred at a stirring rate of 500-600 rpm for 15-20 min; after adding the flame retardant stabilizer, the stirring rate is increased to 800-1000 rpm and stirred for 25-30 min; after adding the interface modifier, the stirring rate is maintained at 800-1000 rpm and stirring is continued for 30-35 min; in step S4, the degassing treatment temperature is 65-75℃, the vacuum degree is -0.09--0.08 MPa, the stirring rate is 300-350 rpm, and the time is 30-35 min.

8. The application of the non-fluorine flame-retardant two-phase coolant according to any one of claims 1-3 in an immersion liquid cooling system.

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