Novel nanofluid cooling liquid applied to cooling system of wind generating set

Abstract

The invention relates to the technical field of wind generating set cooling, in particular to a novel nanofluid cooling liquid applied to a wind generating set cooling system, which combines ultrahigh pressure homogenization and micro-channel mixing technologies, significantly improves the heat conductivity coefficient of the cooling liquid, fixes nanoparticles through a three-dimensional network structure, and improves the heat conductivity coefficient of the cooling liquid. Therefore, the heat dissipation efficiency and the operation reliability of key components such as the frequency converter of the wind generating set are effectively improved; a metal inerting agent and a synergistic antioxidant system are combined to form a multi-layer protection mechanism, so that metal corrosion and fluid oxidation are remarkably inhibited, the service life of the system is greatly prolonged, and the maintenance frequency and cost are reduced; on-line monitoring and fault diagnosis mechanisms are combined, a clear performance-process parameter association database is set in the preparation process, quality controllability and problem traceability of the whole process from raw material processing to finished product filling are achieved, and product batch consistency and reliability are guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wind turbine cooling technology, in particular to a new type of nanofluid cooling liquid applied to a wind turbine cooling system. BACKGROUND

[0002] As the core pillar of the clean and renewable energy field, wind turbines are accelerating towards large-scale and high-efficiency iteration. This development trend has greatly increased the power density of core components such as AC frequency converters, generators, and variable pitch systems, which in turn has led to a geometric increase in device heat generation, posing unprecedentedly stringent requirements on the thermal conductivity, long-term corrosion resistance, and high-temperature stability of the cooling liquid.

[0003] After searching, patent No. CN115260999B "Cooling liquid for wind turbine and preparation method thereof" discloses the following technical solution: the cooling liquid contains 0.20-2.00% of polyether amine, 0.01-0.05% of azole organic compound, 0.01-0.20% of organic silicon, 0.01-0.10% of stabilizer, and 30-60% of antifreeze, with the balance being water. This solution selects components with low ionization or slow dissociation, enabling the cooling liquid to achieve a low conductivity of less than 150 μs / cm, and specifically addressing the pitting and crevice corrosion problems of various aluminum alloy materials such as 3003, 4043, 4104, 5052, and 6061 in wind turbines, providing basic corrosion protection for the unit. However, this technical solution is difficult to adapt to the core needs of wind turbines moving towards high power and long life, and its limitations mainly lie in three key dimensions.

[0004] Firstly, the passive mechanism of corrosion inhibition cannot cope with complex corrosion scenarios. This solution relies too much on the uniform adsorption of organic corrosion inhibitors such as polyether amine on the metal surface to form a protective layer. This passive protection mode is prone to problems such as discontinuous adsorption layer and protection failure when facing local micro-environment changes caused by component assembly gaps, mechanical stress concentration, etc., making it difficult to effectively resist the occurrence and spread of local pitting.

[0005] Secondly, there is a significant shortcoming in thermal conductivity. This formula does not optimize the thermal conductivity system for high heat emission of large power turbines. The combination of conventional water-based systems with basic organic additives cannot match the rapid increase in heat dissipation demand of core components, leading to heat accumulation and affecting the operation efficiency and component life of the unit.

[0006] Thirdly, the long-term stability under high temperature is insufficient. The conventional antioxidant system in the scheme is prone to gradual failure during long-term high-temperature operation of the unit, which not only causes problems such as acidification of the coolant and degradation of components, but also triggers a chain reaction of abnormal rise of electrical conductivity and accelerated metal corrosion. This series of problems will continuously erode the cooling system and core components of the unit, seriously damage the stability of long-term operation of the system, and greatly shorten the maintenance cycle and overall service life of the unit. SUMMARY

[0007] The technical problems solved by the application are as follows: Although the above scheme realizes basic protection of specific aluminum alloys by using organic corrosion inhibitors such as polyetheramine, the passive corrosion inhibition mechanism and limited thermal conductivity cannot meet the development needs of wind turbine generators towards high power and long service life. The above formula relies too much on uniform adsorption of corrosion inhibitors on the metal surface, and cannot cope with local pitting caused by factors such as gaps and stress. Moreover, the conventional antioxidant system is prone to failure under long-term high-temperature operation, leading to acidification of the coolant, degradation of components, and further triggering a chain reaction of rising electrical conductivity and accelerated corrosion, which seriously threatens the stability and service life of long-term operation of the system.

[0008] In view of the deficiencies of the prior art, the application provides a new nanofluid coolant for a wind turbine generator cooling system and its application, thereby solving the technical problems mentioned in the background art.

[0009] To achieve the above object, the application is implemented by the following technical solutions: A new nanofluid coolant for a wind turbine generator cooling system, which is composed of the following components by weight percentage: Deionized water and glycerol complexing agent: deionized water and industrial-grade glycerol are mixed at a mass ratio of 5:1 to 7:1, accounting for 78% to 90% of the coolant; Core-shell structure composite nanoparticles: composite particles with high thermal conductivity nanodiamond as core and mesoporous silica as shell, accounting for 1.5% to 4.5% of the coolant; Multifunctional composite dispersion stabilizer: composed of ionic dispersant fatty alcohol polyoxyethylene ether phosphate and non-ionic dispersant block polyether L64 at a weight ratio of 1.5:1, accounting for 2.0% to 3.5% of the coolant; Self-repairing composite corrosion inhibitor: compounded by methyl benzotriazole, sodium tungstate and pH-responsive microcapsules at a weight ratio of 1:1.8:0.7, the pH-responsive microcapsules use gelatin and gum arabic as wall material and cyclohexanehexaphosphate as core material, accounting for 2.5% to 4.5% of the coolant; Synergistic antioxidant system: composed of main antioxidant beta-(3,5-di-tert-butyl-4-hydroxyphenyl) octadecyl propionate and auxiliary antioxidant triphenyl phosphite at a weight ratio of 3:1, accounting for 0.4% to 1.0% of the coolant; Intelligent pH regulator and stabilizer: 2-amino-2-methyl-1-propanol, 0.3% to 0.7% of the coolant; Metallic inactivator: sodium salt of mercaptobenzothiazole, 0.15% to 0.35% of the coolant; Nano defoaming agent: paste formed by dispersing hydrophobic silica nanoparticles in a polydimethylsiloxane carrier, 0.08% to 0.18% of the coolant.

[0010] Further, the deionized water is treated by three-stage purification: sequentially passing through quartz sand filtration to remove suspended solids, activated carbon adsorption to remove organic matter, and mixed ion exchange resin column to remove ion impurities, with a final conductivity of ≤1.0 μS / cm, and stored in a sealed pressure tank filled with high-purity nitrogen; the glycerol purity is ≥99.8%.

[0011] Further, the preparation method of the core-shell structure composite nanoparticles includes: Disperse the initial particle size of 50-100 nm nanodiamonds in an alkaline aqueous solution with pH=10.5, and stir at 300-500 r / min for 30-60 min for surface hydroxyl activation; Add cetyltrimethylammonium bromide as a template agent to the above system in a molar ratio of 1:15 with tetraethyl orthosilicate, and react at 50-60°C for 4-6 h to form an ordered mesoporous silica shell layer on the surface of the nanodiamonds in situ, with a pore size of 2-5 nm; After the reaction is completed, remove the unreacted substances by centrifugal washing, and calcine at 550°C for 4 hours to remove the template agent, to obtain core-shell structure composite nanoparticles.

[0012] Further, in the multifunctional composite dispersion stabilizer, the fatty alcohol polyoxyethylene ether phosphate provides electrostatic repulsion, the block polyether L64 provides steric hindrance effect, and the two dispersants synergistically inhibit the agglomeration of the core-shell structure composite nanoparticles.

[0013] Further, the pH-responsive microcapsules are prepared by complex coacervation: dissolve gelatin and gum arabic in deionized water at a mass ratio of 1:1, add cyclohexanehexol hexaphosphate (wall material to core material mass ratio 2:1), adjust the pH to 4.0-4.5 at 40-50°C, stir for 1-2 h, and then cool to below 5°C to solidify, to obtain microcapsules with an average particle size of 700-900 nm (average 800 nm); the microcapsules are stable at a coolant pH of 8.5, and when local corrosion causes the pH to drop below 7.5, the wall material dissolves to release cyclohexanehexol hexaphosphate.

[0014] Further, in the synergistic antioxidant system, the main antioxidant terminates the oxidation chain reaction by providing hydrogen atoms, and the auxiliary antioxidant decomposes hydroperoxide into non-radical products, so that the oxidation induction period of the coolant exceeds 1500 hours under the condition of normal pressure and 120℃; 2-amino-2-methyl-1-propanol stabilizes the pH value of the coolant at 8.5-8.8.

[0015] Further, in the metal inactivator, the sulfur atom in the molecule preferentially chemisorbs with the active sites on the metal surface to form an inert protective film with high chemical stability.

[0016] Further, in the nanometer defoaming agent, the hydrophobic silica nanoparticles form defect points by inserting into the foam liquid film to destroy the surface tension balance of the liquid film to eliminate foam, wherein the particle size of the hydrophobic silica is 10-50 nm.

[0017] Further, the cooling system for the wind turbine generator set includes cooling of the alternating frequency converter, the generator or the gear box.

[0018] Compared with the prior art, the present application has the following beneficial effects: I. Breakthrough in thermal conductivity performance to adapt to the heat dissipation needs of high-power units To solve the problem of low thermal conductivity of conventional water-based systems and the difficulty in matching the high heat emission of high-power units, the present application innovatively uses core-shell structure composite nanoparticles with high thermal conductivity nanodiamond as the core and mesoporous silica as the shell. Through ultra-high pressure homogenization (three-stage pressure gradient: 50MPa / 150MPa / 250MPa) and micro-channel mixing (channel diameter 500μm + high pressure pulse synergy) technology, the nanoparticles are highly dispersed in the base fluid (D50≤45nm, PDI≤0.10), and the three-dimensional network structure is used to fix the particles. This design not only increases the thermal conductivity of the coolant at 25℃ to 0.75-0.82W / (m・K), which is 15%-20% higher than that of conventional water-based systems, but also keeps the particles stable and non-settled under extreme temperature cycles of-45℃ to 110℃, effectively solving the heat accumulation problem of core components such as alternating frequency converters and generators of high-power units, significantly improving the equipment heat dissipation efficiency and long-term operation reliability, and avoiding performance degradation or component damage caused by overheating. II. Constructing an active-passive synergistic corrosion prevention system to prolong the service life of the system and reduce maintenance costs To solve the problem of passive adsorption of organic corrosion inhibitors and the failure of local pitting protection, and the easy failure of antioxidant system at high temperature leading to chain corrosion, the present application constructs a multi-layer protection mechanism. First, the self-repairing corrosion inhibition design based on pH-responsive microcapsules can rapidly release hexaphosphorylated cyclohexanehexol to target repair the corrosion points on the metal surface when the pH drops below 7.5 due to local corrosion, breaking through the limitations of existing passive protection; Second, the metal inactivator (sodium mercaptobenzothiazole) is used to form an inert protective film on the metal surface to block the active sites from contacting the corrosion medium; third, the primary and auxiliary antioxidants (β-(3,5-di-tert-butyl-4-hydroxyphenyl) octadecyl propionate and triphenyl phosphite, weight ratio 3:1) are used to extend the oxidation induction period of the coolant at 120°C to more than 1500 hours, which is 2-3 times higher than the existing conventional antioxidant system. The multi-layer protection mechanism works together to control the corrosion rate of the coolant on Q235 steel, 3003 / 6061 aluminum alloy, etc. to ≤0.005 mm / a, effectively inhibiting metal corrosion and fluid acidification degradation, avoiding abnormal conductivity rise, significantly extending the service life of the cooling system to more than 5 years, reducing maintenance frequency by more than 40%, and significantly reducing operation and maintenance costs. Three, precise control of the whole process to ensure product stability and batch consistency To solve the problem of performance fluctuation of the existing scheme due to lack of production process control, the present scheme uses multi-stage dispersion, structure shaping (micro-channel mixing + high-pressure pulse treatment for 120 minutes), maturation and solidification (25°C standing for 48 hours), etc. Precise process steps combined with online pH monitoring, laser particle size analysis, turbidity detection and other real-time control means ensure that the coolant performs well throughout its life cycle: pH is stably controlled at 8.5-8.8 (avoiding the pH fluctuation risk of the existing scheme), foam is completely eliminated within 5 minutes and does not regenerate at high temperature, and performance does not decay after 6 months of long-term storage. At the same time, a performance-process parameter correlation database is established, combined with a fault diagnosis and traceability mechanism (such as problems such as abnormal ultra-high pressure homogenization pressure and substandard microcapsule encapsulation rate can be accurately located and solved), realizing the whole process quality control from raw material three-stage purification (deionized water conductivity ≤1.0 μS / cm) to finished product hundred-level clean filling, ensuring product batch consistency and reliability, and avoiding the risk of cooling system adaptation due to production fluctuations. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 Flowchart of the preparation method of the novel nanofluid coolant of the present application; DETAILED DESCRIPTION

[0020] The preferred embodiments of the present application will be described in detail with reference to the accompanying drawings, however the present application can be implemented in various different forms, and therefore the present application is not limited to the embodiments described below; The technical solutions in the embodiments of the present application are to solve the problems in the prior art. The above-mentioned solutions in the prior art can realize basic protection of specific aluminum alloys by using organic corrosion inhibitors such as polyether amines, but the passive corrosion inhibition mechanism and limited heat conduction performance are difficult to meet the development needs of wind turbine generators to high power and long service life. The above-mentioned formula relies too much on the uniform adsorption of corrosion inhibitors on the metal surface, and it is difficult to deal with local pitting caused by gaps, stress and other factors. In addition, the conventional antioxidant system is prone to failure under long-term high-temperature operation, leading to acidification of the coolant, degradation of components, and a chain reaction of rising electrical conductivity and accelerated corrosion, which seriously threatens the stability and service life of the system during long-term operation. The overall idea is as follows: Embodiments: The present embodiment introduces a new type of nanofluid coolant applied to the cooling system of a wind turbine generator. The specific content is as follows: I. Material composition The nanofluid coolant is composed of the following components by weight percentage (the total weight percentage of each component is 100%): 1. Base fluid Deionized water and glycerol complexing agent: 78% to 90% of the coolant, mix deionized water and industrial grade glycerol according to the mass ratio of 5:1 to 7:1, start the reaction kettle stirring device, set the speed to 350 rpm, stir for 40 minutes until the system is clear and uniform; The deionized water needs to be purified by three stages, including removing suspended solids by quartz sand filtration, removing organic matter by activated carbon adsorption, and removing ionic impurities by mixed ion exchange resin column, finally the electrical conductivity is ≤1.0 μS / cm, stored in a sealed pressure tank filled with high-purity nitrogen to prevent oxygen and carbon dioxide from dissolving into the system to cause acidification; The purity of glycerol is ≥99.8%, which contains three hydroxyl groups in its molecule, has a higher boiling point and better hygroscopicity and stability than ethylene glycol, can achieve a freezing point of ≤-40℃, its high-temperature anti-evaporation performance is improved by about 15%, and its biological toxicity is lower and more environmentally friendly.

[0021] 2. Nanoparticles Core-shell structure composite nanoparticles: 1.5% to 4.5% of the coolant, which is a composite particle with high thermal conductivity nanodiamond as the core and mesoporous silica as the shell, the core particle size is 50-100 nm, the shell thickness is 20-30 nm, the mesoporous pore size is 2-5 nm, and the total specific surface area is ≥350 m² / g; the preparation process is as follows: first, disperse the nanodiamond in an alkaline aqueous solution with pH=10.5, stir at 300-500 r / min for 30-60 minutes, and perform surface hydroxyl activation (ultrasonic assisted treatment with power 1000 W and frequency 40 kHz for 1 hour to enhance dispersion effect); then, add cetyltrimethylammonium bromide as a template agent and tetraethyl orthosilicate in a molar ratio of 1:15 to the reaction system, and hydrolysis condensation reaction at a temperature of 50-60°C and a stirring speed of 300-500 rpm for 4-6 hours to form a silica shell with ordered mesopores on the surface of the nanodiamond in situ; after the reaction, remove the template by centrifugal washing and calcination at 550°C for 4 hours to obtain core-shell structure composite nanoparticles coated with mesoporous shell; this structure uses nanodiamond with extremely high intrinsic thermal conductivity (about 2200 W / m·K) as a heat conduction highway, while the mesoporous silica shell greatly increases the specific surface area, and the rich silicon hydroxyl groups on its surface facilitate the combination with dispersant molecules, improving the dispersion stability.

[0022] 3. Functional additives Multifunctional composite dispersant stabilizer: 2.0% to 3.5% of the coolant, composed of ionic dispersant fatty alcohol polyoxyethylene ether phosphate and non-ionic dispersant block polyether L64 in a weight ratio of 1.5:1; fatty alcohol polyoxyethylene ether phosphate provides strong electrostatic repulsion, block polyether L64 provides steric hindrance effect, and the two dispersants work together to effectively inhibit the agglomeration of core-shell structure composite nanoparticles, delay the sedimentation rate, and achieve system stability.

[0023] 4. Self-repairing composite corrosion inhibitor 2.5%~4.5% of the coolant, which is compounded by methyl benzotriazole, sodium tungstate and pH responsive microcapsule with a weight ratio of 1:1.8:0.7; the pH responsive microcapsule is prepared by complex coacervation method with gelatin and gum arabic as wall material and hexahydroxy cyclohexane phosphate as core material, specifically: gelatin and gum arabic are dissolved in deionized water with a mass ratio of 1:1, hexahydroxy cyclohexane phosphate (wall material to core material mass ratio 2:1) is added, the pH is adjusted to 4.0-4.5 at 40-50℃, and after stirring for 1-2h, it is cooled to below 5℃ for solidification, obtaining microcapsules with an average particle size of 700-900nm (average 800nm); it is stable at normal pH 8.5 of the coolant, when the local pH drops to below 7.5 due to corrosion, the wall material dissolves to release hexahydroxy cyclohexane phosphate, which can form a stable chelate with a variety of metal ions, rapidly forming a dense protective film at the metal corrosion active site, achieving on-demand supply and targeted repair of the corrosion inhibitor.

[0024] 5. Synergistic antioxidant system: 0.4%~1.0% of the coolant, which is a composite system composed of main antioxidant β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate octadecanol and auxiliary antioxidant triphenyl phosphite with a weight ratio of 3:1, the two produce a synergistic effect, the main antioxidant terminates the oxidation chain reaction by providing hydrogen atoms, and the auxiliary antioxidant decomposes hydroperoxide into non-radical products, together extending the oxidation induction period of the coolant to more than 1500 hours under normal pressure at 120℃.

[0025] 6. Intelligent pH adjusting and stabilizing agent: 0.3%~0.7% of the coolant, 2-amino-2-methyl-1-propanol is selected, which has stronger buffering capacity and higher base reserve value than triethanolamine, can accurately stabilize the coolant pH value in the optimal range of 8.5~8.8, and can resist pH fluctuations caused by the invasion of acidic substances.

[0026] 7. Metal inactivator: 0.15%~0.35% of the coolant, which is sodium mercaptobenzothiazole, the sulfur atom in its molecule can preferentially chemisorb on the active sites of the metal surface, forming a layer of high chemical stability inert protective film, effectively blocking the dissolution of metal ions and inhibiting their catalytic effect on the oxidation of the base fluid.

[0027] 8. Nano defoaming agent: 0.08%~0.18% of the coolant, which is a paste formed by dispersing hydrophobic silica nanoparticles (particle size 10-50nm) in polydimethylsiloxane carrier, the nano-sized hydrophobic particles can insert into the foam film to form defect points, and cooperate with the low surface tension of polysiloxane to destroy the surface tension balance of the liquid film, achieving rapid defoaming and persistent foam suppression, especially after being subjected to long-term high shear of circulating pump, it can still maintain high efficiency.

[0028] II. Preparation method of nanofluid coolant S1, basic fluid treatment and protection: metered deionized water and glycerol were pumped into a 316L stainless steel reactor with jacketed insulation (maintained at 25±2℃), the top of the reactor was connected to a high-purity nitrogen (purity 99.999%) protection system, maintaining a slight positive pressure (+0.05 MPa) in the reactor. Turn on the double-layer inclined blade turbine stirrer, set the speed to 350 rpm, and continue stirring for 40 minutes. Then slowly add the formula amount of 2-amino-2-methyl-1-propanol through a precision metering diaphragm pump, continue stirring for 25 minutes after adding, and monitor and feedback control in real time through a high-precision online pH meter (accuracy ±0.01) to ensure that the pH value of the mixed solution is accurately and stably maintained in the range of 8.5-8.8.

[0029] S2, multi-stage preparation of mother liquor: in another premix tank equipped with a disc-type ultrasonic transducer (power 1.5 kW), add about 25% of the total amount of the mixed solution with adjusted pH. Start the high-speed homogenizing stirrer and set the speed to 4000 rpm to form a strong vortex. Under the synergistic action of stirring and ultrasonic cavitation, methyl benzotriazole, sodium tungstate, pH-responsive microcapsules, composite antioxidants (premixed with primary and secondary antioxidants), and sodium mercaptobenzothiazole are added in sequence. Maintain this synergistic dispersion condition for 60 minutes, and the cavitation effect of ultrasonic waves effectively breaks up the possible small aggregates of corrosion inhibitors, ensuring that all components, especially the nanocapsules, are uniformly dispersed, forming an extremely stable composite additive mother liquor.

[0030] S3, directional assembly and dispersion: the prepared core-shell structure composite nanoparticles and multifunctional composite dispersion stabilizer (fatty alcohol polyoxyethylene ether phosphate, block polyether L64) are added to the remaining basic fluid. First, use a high-speed shear emulsifier at 12000 rpm for primary dispersion for 15 minutes to initially open the particle agglomeration using strong mechanical force. Then, use an ultrahigh pressure homogenizer for final dispersion: set the three-stage homogenization pressure to 50 MPa (first stage), 150 MPa (second stage), and 250 MPa (third stage), and circulate the material 6 times. During the homogenization process, use a -5℃ ethylene glycol water solution as the cooling medium through an external double-helix tube cooler to ensure that the discharge temperature is always below 30℃. After this treatment, the nanoparticles are not only fully dispersed into primary particles, but the mesoporous silica shell on their surface also forms a firm adsorption layer with the dispersion agent molecules. The final dispersion has a D50 particle size ≤45 nm and a PDI ≤0.10.

[0031] S4, Structure shaping The composite additive mother liquor prepared in S2 is slowly pumped into the nanodispersion prepared in S3 by a constant flow pump at a controllable flow rate (50 L / h), and the receiving container is the main reactor, which is continuously stirred at 250 rpm. Then, the microchannel mixer (channel diameter 500 pm) built-in the reactor and the external loop high-pressure pulse device (pulse frequency 10 Hz, pressure peak 5 MPa) are started, so that the mixed liquid undergoes high-intensity vortex and pulse shear at the microscale. This process lasts for 120 minutes, which promotes the physical and chemical interaction between nanoparticles, additive molecules and base fluid, realizes the uniform mixing and stable combination of each component, and ensures the dispersion stability of the system.

[0032] S5, Defoaming and maturation The mixed liquid obtained in S4 is transferred to a static maturation tank, and the stirring speed is reduced to 50 rpm. The nanodefoaming agent is pre-diluted with 10 times the weight of the base fluid, and then uniformly sprayed on the liquid surface by a spraying device. Then the stirring is completely stopped, the maturation tank is sealed, and the maturation is carried out at a constant temperature of 25±1℃ for 48 hours. This long-term maturation process allows the intermolecular forces in the system to fully relax and solidify, reaching a stable state with the lowest energy, and ensuring that the defoaming agent molecules uniformly migrate to the interface to complete self-assembly.

[0033] S6, End filling After maturation is completed, the coolant is detected online by using a laser particle size analyzer and a turbidimeter. The qualified product successively passes through the terminal filtration of the cartridge filter with a pore size of 5 pm (to remove potential mechanical impurities), 1 pm (to remove extremely small amount of soft aggregates), and 0.45 pm (to ensure sterilization). The finished coolant after filtration is filled in a hundred-level clean environment, the filling line uses underwater filling technology to reduce the introduction of air bubbles, and is immediately sealed after replacing the headspace air with nitrogen, and is labeled and stored in the warehouse.

[0034] S7, the prepared nanofluid coolant sample is placed in a programmable high-low temperature impact test box, and the extreme temperature cycle of-45℃ (maintained for 4 hours) to 110℃ (maintained for 4 hours) is executed for 200 times. If any visible stratification or precipitation layer thickness exceeding 0.1% of the total height of the liquid column appears at the bottom after centrifugal acceleration (4000 rpm, 30 min) test, the S3 ultra-high pressure homogenization step needs to be traced back to check whether the three-stage pressure reaches the set value (especially the 250 MPa stage) or the cycle number is insufficient, and the 300 MPa ultra-high pressure single impact treatment needs to be repeated; if the actual thermal conductivity of the coolant is lower than 0.85 W / m・K at 85℃ working condition, the S4 micro-reaction coupling step needs to be traced back to check whether the micro-channel mixer is blocked to cause insufficient mixing intensity, or the pulse device is abnormal, the parts need to be cleaned or replaced and then the coupling process is performed again; if the corrosion rate of low carbon steel exceeds 0.5 mil / year in the accelerated electrochemical corrosion test (referring to ASTM D2776-79, polarization resistance method), the S2 additive mother liquor preparation step needs to be traced back to check the encapsulation rate and stability of the pH-responsive microcapsule, or whether the nitrogen protection in the S1 step is invalid to cause the initial dissolved oxygen content exceeding the standard, the oxygen content analyzer needs to be used for detection and the protection measures need to be strengthened. The corresponding database based on the above key process parameters and final performance indicators is established, and the product quality prediction and intelligent control are realized by using big data analysis.

[0035] III. Performance test and application The new nanofluid coolant obtained by the above material composition and preparation method is tested: the thermal conductivity is 0.75-0.82 W / (m・K) at 25℃, no stratification for 30 days, no precipitation after centrifugation (3000 r / min, 30 min); the corrosion rate of Q235 steel, copper and aluminum is ≤0.005 mm / a; the oxidation induction period is 1550-1650 h at 120℃ under normal pressure; the foam is completely eliminated within 5 min after adding, and no foam is regenerated in the 120℃ cycle test; the pH remains at 8.5-8.7 after 6 months of storage.

[0036] The new nanofluid coolant is suitable for the cooling system of a wind turbine generator set, including the cooling of an alternating current frequency converter, a generator or a gear box, which can stably work at-30℃-120℃ working condition and has a service life of more than 5 years.

[0037] It should finally be noted that the foregoing merely describes examples of the present specification and that modifications, improvements, and alterations are likely to occur to those skilled in the art upon the reading and understanding of this specification. Any modifications, improvements, or alterations are intended to be included within the spirit and scope of the present specification. The present specification has used certain terminology in describing the embodiments of the present specification. Use of such terms as "one embodiment," "an embodiment," and / or "some embodiments" is intended to convey a certain feature, structure, or characteristic described in relation to at least one embodiment of the present specification. It is submitted, therefore, that no inference should be drawn from such terms that the features, structures, or characteristics described in connection with any one embodiment are necessary to every other embodiment. Moreover, it should be noted that certain features, structures, or characteristics described in the context of one or more embodiments of the present specification can be combined with features, structures, or characteristics of other embodiments. In addition, it should be noted that the order in which the process elements and sequences are presented in the description above is not meant to be limiting.

Claims

1. A novel nanofluid coolant for use in wind turbine generator cooling systems, characterized in that, It consists of the following components by weight percentage: Deionized water and glycerol compound: Deionized water and industrial grade glycerol are mixed at a mass ratio of 5:1 to 7:1, accounting for 78% to 90% of the coolant; Core-shell composite nanoparticles: composite particles with highly thermally conductive nanodiamond as the core and mesoporous silica as the shell, accounting for 1.5% to 4.5% of the coolant; Multifunctional composite dispersion stabilizer: composed of ionic dispersant fatty alcohol polyoxyethylene ether phosphate and nonionic dispersant block polyether L64 in a weight ratio of 1.5:1, accounting for 2.0% to 3.5% of the coolant; Self-healing composite corrosion inhibitor: It is composed of methylbenzotriazole, sodium tungstate and pH-responsive microcapsules in a weight ratio of 1:1.8:0.

7. The pH-responsive microcapsules use gelatin and gum arabic as wall materials and cyclohexanehexaphosphate as core material, accounting for 2.5% to 4.5% of the coolant. Synergistic antioxidant system: Composed of the primary antioxidant β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and the auxiliary antioxidant triphenyl phosphite in a weight ratio of 3:1, accounting for 0.4% to 1.0% of the coolant; Intelligent pH adjuster and stabilizer: 2-amino-2-methyl-1-propanol, accounting for 0.3% to 0.7% of the coolant; Metal inertizer: Sodium mercaptobenzothiazole, accounting for 0.15% to 0.35% of the coolant; Nano defoamer: A paste-like substance formed by dispersing hydrophobic silica nanoparticles in a polydimethylsiloxane carrier, accounting for 0.08% to 0.18% of the coolant.

2. The novel nanofluid coolant for use in wind turbine generator cooling systems as described in claim 1, characterized in that, The deionized water undergoes a three-stage purification process: sequentially passing through a quartz sand filter to remove suspended solids, activated carbon adsorption to remove organic matter, and a mixed ion exchange resin column to remove ionic impurities, resulting in a final conductivity ≤1.0μS / cm. It is then stored in a sealed pressure tank filled with high-purity nitrogen; the glycerol purity is ≥99.8%.

3. The novel nanofluid coolant for use in wind turbine generator cooling systems as described in claim 1, characterized in that, The preparation method of the core-shell structured composite nanoparticles includes: Nanodiamonds with an initial particle size of 50-100 nm were dispersed in an alkaline aqueous solution with pH=10.5 and surface hydroxylation was activated by stirring at 300-500 r / min for 30-60 min. Hexadecyltrimethylammonium bromide was used as a template agent and added to the above system with tetraethyl orthosilicate at a molar ratio of 1:

15. The reaction was carried out at 50-60°C for 4-6 hours to form an ordered mesoporous silica shell on the surface of nanodiamonds. The pore size of the mesopores was 2-5 nm. After the reaction was completed, unreacted substances were removed by centrifugation and washing, and the template agent was removed by calcination at 550°C for 4 hours to obtain core-shell structured composite nanoparticles.

4. The novel nanofluid coolant for use in a wind turbine generator cooling system as described in claim 1, characterized in that, In the aforementioned multifunctional composite dispersant and stabilizer, fatty alcohol polyoxyethylene ether phosphate provides electrostatic repulsion, while block polyether L64 provides steric hindrance. The two dispersants work synergistically to inhibit the aggregation of core-shell structured composite nanoparticles.

5. The novel nanofluid coolant for use in a wind turbine generator cooling system as described in claim 1, characterized in that, The pH-responsive microcapsules were prepared using a complex coagulation method: gelatin and gum arabic were dissolved in deionized water at a mass ratio of 1:1, and cyclohexanehexaphosphate (wall material to core material mass ratio of 2:1) was added. The pH was adjusted to 4.0–4.5 at 40–50°C, and the mixture was stirred for 1–2 hours before being cooled to below 5°C to solidify, resulting in microcapsules with an average particle size of 700–900 nm (average 800 nm). The microcapsules were stable at pH 8.5 in the cooling solution. When local corrosion caused the pH to drop below 7.5, the wall material dissolved and released cyclohexanehexaphosphate.

6. The novel nanofluid coolant for use in a wind turbine generator cooling system as described in claim 1, characterized in that, In the synergistic antioxidant system, the primary antioxidant terminates the oxidation chain reaction by providing hydrogen atoms, and the secondary antioxidant decomposes hydrogen peroxide into non-free radical products, thereby enabling the oxidation induction period of the coolant to exceed 1500 hours under normal pressure and 120°C conditions; 2-amino-2-methyl-1-propanol stabilizes the pH of the coolant at 8.5-8.

8.

7. The novel nanofluid coolant for use in a wind turbine generator cooling system as described in claim 1, characterized in that, In the metal inert agent molecule, sulfur atoms preferentially undergo chemical adsorption with active sites on the metal surface to form a highly chemically stable inert protective film.

8. The novel nanofluid coolant for use in a wind turbine generator cooling system as described in claim 1, characterized in that, In the nano defoamer, hydrophobic silica nanoparticles form defect points by inserting into the foam liquid film, thereby disrupting the surface tension balance of the liquid film and eliminating foam. The particle size of the hydrophobic silica is 10-50 nm.

9. A novel nanofluid coolant for use in a wind turbine generator cooling system as described in any one of claims 1 to 8, characterized in that, Cooling systems for wind turbine generators, including cooling of AC inverters, generators, or gearboxes.

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