Heat transfer fluid
By adding non-azole, aromatic, and heterocyclic additives to the heat transfer fluid, the problem of insufficient corrosion protection of aluminum by existing heat transfer fluids is solved, achieving effective protection of aluminum and stability of conductivity, thus avoiding component damage.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ BV
- Filing Date
- 2024-12-11
- Publication Date
- 2026-07-10
AI Technical Summary
Existing heat transfer fluids provide poor corrosion protection in systems containing aluminum, and azole/silicate systems can lead to metal corrosion and scaling problems.
A heat transfer fluid containing 10-90% freezing point depressant, 90-10% water, and 0.005-5% non-azole, aromatic, or heterocyclic additives is used to improve corrosion protection of aluminum.
It significantly improves corrosion protection for copper, stainless steel, and aluminum, reduces conductivity during fluid aging, and prevents short circuits and damage to heating components.
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Abstract
Description
Technical Field
[0001] This invention relates to heat transfer fluids, particularly heat transfer fluids with low conductivity. Background Technology
[0002] Across a range of industries, new technologies are being sought to provide more energy-efficient and lower CO2 solutions. This invention relates to many possible efficiencies driving lower energy demands and lower CO2 emissions. Firstly, this invention relates to electric vehicle technology. Secondly, the invention is also applicable to thermal management of IT equipment, such as servers. However, the invention described herein is not inherently limited to the technologies to which it can be applied. This invention can be applied to any heat-generating electrical technology.
[0003] By 2040, electric vehicles are projected to account for up to 50% of all new passenger vehicle sales. This includes battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), and fuel cell electric vehicles (FCEVs). Hybrid electric vehicles combine batteries with conventional internal combustion engines or fuel cells. Fuel cell electric vehicles also require batteries for buffering and temporary energy storage.
[0004] Current battery technology relies on lithium-ion batteries, and lithium-ion batteries are likely to remain the dominant battery technology for at least the next 15 years. While slow charging at home or at your destination may be the primary charging method, many customers who want to drive long distances will need high-performance fast charging (HPC) on the go. To improve and shorten the charging process, it is necessary to increase the voltage, current, or both. Higher currents also increase the amount of residual heat generated. The level of residual heat can be very high, reaching 20 kWh or higher. Effective thermal management is needed to control the temperature uniformity within the battery pack to prevent irreversible degradation of the battery cells.
[0005] In electric vehicles, other components also require thermal management, particularly cooling. During operation, both the electric motor and the inverter generate heat. Thermal management methods applicable to each of these components and preferably integrated into the circuitry containing all of these components (including the battery) would be most desirable.
[0006] Fuel cell-powered electrical systems also generate a significant amount of waste heat during operation (approximately 50% of the energy is generated as waste heat), which needs to be removed during operation.
[0007] Thermal management of components also presents challenges for other industries. The thermal management of IT components, especially servers, presents numerous challenges. Air cooling of these components requires high energy consumption and expensive cooling infrastructure. Simpler, more energy-efficient systems for thermal management of these electronic components are highly desirable.
[0008] Many cooling systems have historically used air passing through a heat source to manage excess heat. However, such systems are limited in terms of heat capacity and cannot manage heat generated, for example, in electrical equipment subjected to strain from processes such as HPC. The infrastructure included in air-cooled systems can also be complex, expensive, and involve the maintenance of many moving components.
[0009] More advanced thermal management systems have been developed that use a conventional water / glycol mixture as the heat transfer fluid. Battery packs containing a large number of individual battery cells can be effectively cooled using the water / glycol mixture. This is rapidly becoming the primary thermal management technology used in electric vehicles sold today because it is more efficient than air cooling.
[0010] Developing improved working fluids for thermal management in electrical systems remains an ongoing challenge. Such working fluids require excellent material compatibility, thermodynamic properties, and low flammability. Importantly, the fluid must possess a low conductivity level that can be maintained as the fluid ages to prevent short circuits and / or damage to heat-generating components.
[0011] To maintain corrosion protection, additives are contained in typical low-conductivity heat transfer fluids. Of particular note is the heat transfer fluid formulation described in US2006 / 0219975, which contains one or more azole derivatives and orthosilicates to provide protection for metals in the heat transfer system.
[0012] While the aforementioned azole / silicate systems are known for protecting “yellow” metals such as copper and brass, they offer less effective corrosion protection against aluminum, a critical component of modern heat transfer systems. Furthermore, overtreatment with silicates can actually lead to metal corrosion and / or the formation of sludge / scale in heat transfer systems.
[0013] There remains a need for suitable low-conductivity heat transfer fluids that provide improved corrosion protection, especially for systems containing aluminum. Summary of the Invention
[0014] This invention provides a heat transfer fluid comprising:
[0015] (a) 10% to 90% by mass of freezing point depressant based on the total mass of the heat transfer fluid;
[0016] (b) Based on the total mass of the heat transfer fluid, 90% to 10% by mass of water; and
[0017] (c) Based on the total mass of the heat transfer fluid, 0.005% to 5% by mass of a first additive, wherein the first additive is a nonazole, aromatic, or heterocyclic additive.
[0018] The present invention also provides a heat transfer system, the heat transfer system comprising:
[0019] A shell with internal space;
[0020] Heating components housed within the internal space; and
[0021] A heat transfer fluid, disposed within an internal space, such that the heating element is in contact with the heat transfer fluid; wherein the heat transfer fluid comprises:
[0022] -Based on the total mass of the heat transfer fluid, 10% to 90% by mass of freezing point depressant;
[0023] -Based on the total mass of the heat transfer fluid, 90% to 10% water by mass; and
[0024] -Based on the total mass of the heat transfer fluid, 0.005% to 5% by mass of a first additive, wherein the first additive is a non-azole, aromatic, or heterocyclic additive.
[0025] Furthermore, the present invention provides the use of a heat transfer fluid in a heat transfer system to provide improved metal corrosion inhibition, wherein, based on the total mass of the heat transfer fluid, the heat transfer fluid comprises 10% to 90% by mass of a freezing point depressant; 90% to 10% by mass of water, based on the total mass of the heat transfer fluid; and
[0026] Based on the total mass of the heat transfer fluid, 0.005% to 5% by mass of a first additive, wherein the first additive is a non-azole, aromatic, or heterocyclic additive. Detailed Implementation
[0027] One or more specific embodiments of this disclosure will now be described. These described embodiments are examples of the currently disclosed technology. Furthermore, for the purpose of providing a concise description of these embodiments, not all features of an actual specific implementation can be described in the specification.
[0028] When describing the elements of various embodiments of this disclosure, the articles “a,” “an,” and “the” are intended to indicate the presence of one or more elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that additional elements besides those listed may also be present. Furthermore, it should be understood that references to “an embodiment” or “an embodiment” of this disclosure are not intended to be construed as excluding the existence of additional embodiments that also incorporate the described features.
[0029] In the context of this invention, when a composition comprises two or more components, these components are selected in a total amount not exceeding 100% by mass.
[0030] The inventors have surprisingly discovered that heat transfer fluids containing non-azole aromatic heterocyclic additives with two or more heteroatoms provide significantly improved corrosion protection in heat transfer fluid systems.
[0031] The heat transfer fluid contains a freezing point depressant. Suitable freezing point depressants for heat transfer fluids according to this teaching include, but are not limited to, alcohols and mixtures of alcohols (e.g., monohydric alcohols, polyhydric alcohols, and mixtures thereof). Representative alcohols used as freezing point depressants include, but are not limited to, methanol, ethanol, propanol, butanol, furfural, furfuryl alcohol, tetrahydrofurfuryl alcohol, ethoxylated furfuryl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol (1,2-propanediol), 1,3-propylene glycol (1,3-propanediol), dipropylene glycol, butanediol, glycerol, glycerol 1,2-dimethyl ether, glycerol 1,3-dimethyl ether, glycerol monoethyl ether, sorbitol, 1,2,6-hexanetriol, trimethylolpropane, C1-C4 alkoxyalkanols (e.g., methoxyethanol), and combinations thereof. Preferably, the freezing point depressant comprises an alcohol selected from the group consisting of ethylene glycol, 1,2-propanediol, 1,3-propanediol, glycerol, and combinations thereof. Most preferably, the freezing point depressant is a diol.
[0032] The concentration of the freezing point depressant is between 10% and 90% by mass based on the total mass of the heat transfer fluid, and can vary depending on the application. Preferably, the freezing point depressant is present in an amount of at least 20% by mass, more preferably at least 30% by mass, and even more preferably at least 40% by mass based on the total mass of the heat transfer fluid. Furthermore, the freezing point depressant may be present in an amount of up to 80% by mass, more preferably up to 70% by mass, and even more preferably up to 60% by mass based on the total mass of the heat transfer fluid.
[0033] The water present in the heat transfer fluid is suitably deionized or distilled water. The concentration of water, based on the total mass of the heat transfer fluid, is between 10% and 90% by mass, and can vary depending on the application. Preferably, water is present in an amount of at least 20% by mass, more preferably at least 30% by mass, and even more preferably at least 40% by mass, based on the total mass of the heat transfer fluid. Furthermore, water may be present in an amount of up to 80% by mass, more preferably up to 70% by mass, and even more preferably up to 60% by mass, based on the total mass of the heat transfer fluid.
[0034] By definition, azoles comprise a five-membered aromatic ring containing at least two heteroatoms, at least one of which is nitrogen. Typically, the remaining heteroatoms in azoles are selected from the group consisting of sulfur, nitrogen, and oxygen. Therefore, the term azoles encompasses, but is not limited to, imidazoles, oxazoles, thiazoles, isazoles, isothiazoles, and pyrazoles.
[0035] The first additive in the heat transfer fluid of the present invention is a non-azole, aromatic, heterocyclic additive. Therefore, the first additive does not contain a five-membered aromatic ring containing nitrogen and at least one other heteroatom.
[0036] The first additive preferably comprises one or more compounds selected from: (i) compounds containing an optionally substituted six-membered aromatic ring having two heteroatoms; and (ii) optionally substituted compounds of formula (I).
[0037]
[0038] Where X is selected from O, S and NH, and R is selected from N and CH.
[0039] The first additive comprises a compound selected from those containing an optionally substituted six-membered aromatic ring having two heteroatoms, preferably including at least one, and more preferably two, nitrogen atoms. If present, the substitution of the six-membered aromatic ring appropriately includes an additional aromatic ring. Preferred compounds are selected from those containing an optionally substituted six-membered aromatic ring having two heteroatoms, chosen from the list of the following: quinazolines, pyrazines, and pyridazines.
[0040] When the first additive contains a compound of formula (I) with optional substitution, preferably the compound is selected from a list consisting of 7-aza-indole, benzofuran and benzothiophene.
[0041] Preferably, the heat transfer fluid further comprises one or more azole derivatives. More preferably, the azole derivatives are selected from the list of the following: benzimidazole, benzotriazole, toluenetriazole, and mixtures thereof.
[0042] In addition to the first additive and optional azole derivatives, the heat transfer fluid may contain other additives. These other additives may be selected from a list including: nonionic surfactants, low conductivity corrosion inhibitors, nonconductive colorants, defoamers or defoamers, biocides, pH adjusters, wetting agents, other nonconductive or low conductivity corrosion inhibitors, nonionic dispersants, scale inhibitors, bittering agents, other heat transfer fluid / antifreeze additives, and combinations thereof. If present, one or more optional additional components should be nonconductive or have low conductivity.
[0043] Preferably, the heat transfer fluid is substantially free of silicon-containing compounds.
[0044] The invention will now be described with reference to the following non-limiting embodiments.
[0045] Example
[0046] As shown in Tables 1 and 2, a series of heat transfer fluid compositions were blended and tested.
[0047] Table 1
[0048]
[0049] Table 2 (Comparative Examples)
[0050]
[0051] All examples were tested according to a modified ASTM D1384 (Corrosion Test for Glassware) performed for 2 weeks at 80°C with a ventilation rate of 100 mL / min. Conductivity was measured according to ASTM D1125. The metal corrosion rate was also measured in milliliters per year (mpy) based on the electrochemical testing platform.
[0052] Compared to simple ethylene glycol / water fluids (reference example), the formulations according to the present invention provide significantly improved protection against copper, stainless steel, and aluminum corrosion. Compared to heat transfer fluids containing only azoles and azole / TEOS additives (Comparative Examples 1 to 5), the heat transfer fluids of the present invention provide significantly improved protection against aluminum corrosion. Examples 3 and 4 demonstrate the superior results of the heat transfer fluids of the present invention, wherein non-azole, aromatic, heterocyclic additives are used in combination with azole-based additives such as TTZ.
Claims
1. A heat transfer fluid, said heat transfer fluid comprising: (a) 10% to 90% by mass of freezing point depressant based on the total mass of the heat transfer fluid; (b) 90% to 10% by mass of water, based on the total mass of the heat transfer fluid; and (c) Based on the total mass of the heat transfer fluid, 0.005% to 5% by mass of a first additive, wherein the first additive is a non-azole, aromatic, or heterocyclic additive.
2. The heat transfer fluid according to claim 1, wherein the freezing point depressant is a diol.
3. The heat transfer fluid according to claim 1 or claim 2, wherein the first additive comprises one or more compounds selected from: (i) a compound containing an optionally substituted six-membered aromatic ring having two heteroatoms; and (ii) an optionally substituted compound of formula (I). Where X is selected from O, S and NH, and R is selected from N and CH.
4. The heat transfer fluid of claim 3, wherein the first additive comprises a compound selected from those containing an optionally substituted six-membered aromatic ring, the ring containing two nitrogen atoms.
5. The heat transfer fluid of claim 4, wherein the first additive comprises one or more compounds selected from the list of the following: quinazoline, pyrazine, and pyridazine.
6. The heat transfer fluid of claim 3, wherein the first additive comprises an optionally substituted compound of formula (I), the compound being selected from the list of the following: 7-aza-indole, benzofuran, and benzothiophene.
7. The heat transfer fluid according to any one of claims 1 to 6, wherein the heat transfer fluid further comprises one or more azole derivatives, said one or more azole derivatives preferably selected from the list of the following: benzimidazole, benzotriazole, toluenetriazole, and mixtures thereof.
8. A heat transfer system, the heat transfer system comprising: A shell with internal space; Heating components are installed within the internal space; and A heat transfer fluid, wherein the heat transfer fluid is disposed within the internal space such that the heating component is in contact with the heat transfer fluid; wherein the heat transfer fluid comprises: - 10% to 90% by mass of freezing point depressant based on the total mass of the heat transfer fluid; -Based on the total mass of the heat transfer fluid, 90% to 10% by mass is water; and -Based on the total mass of the heat transfer fluid, 0.005% to 5% by mass of a first additive, wherein the first additive is a non-azole, aromatic, or heterocyclic additive.
9. Use of the heat transfer fluid according to any one of claims 1 to 7 in a heat transfer system to provide improved metal corrosion inhibition.
10. The use according to claim 9, wherein the use is to provide improved copper and aluminum corrosion inhibition.