Heat Transfer Mixture

Abstract

The heat transfer mixture is represented by the equation: 1 = Vpg / Vnf + Vw / Vnf + Vpw / Vnf + Vsf / Vnf + Vbs / Vnf + Vac / Vnf + Vci / Vnf. Vnf is the volume of nanofluid. Vpg is the volume of propylene glycol. Vw is the volume of water. Vpw is the volume of nanopowder. Vsf is the volume of surfactant. Vbs is the volume of base additive. Vac is the volume of acid additive. Vci is the volume of corrosion inhibitor.

Description

[Technical Field]

[0001] Technical Field FIELD OF THE DISCLOSURE

[0001] The present disclosure relates generally to refrigerants, and more particularly to nanofluids comprising aluminum oxide nanoparticles for use in thermal systems. [Background technology]

[0002] background For well over a century, micro-sized particles with high thermal conductivity have been used to increase the thermal properties of working fluids. However, micro-sized particles can be abrasive and can precipitate due to their high density. More recently, nano-sized particles have been introduced into a base liquid to form nanofluids. In particular, copper-, aluminum-, or carbon-based nanoparticles have been used to form colloidal suspension fluids with improved thermal properties.

[0003] Conventional nanofluids have demonstrated varying degrees of improvement in thermal performance through the addition of nanoparticles to thermal fluids. Many conventional nanofluids utilize copper(II) oxide (CuO) nanoparticles to form nanofluids due to the favorable thermal properties of copper(II) oxide powder. However, nanofluids formed using copper(II) oxide nanofluids have several drawbacks that may hinder their commercial use in thermal systems. For example, fluids containing copper(II) oxide nanoparticles tend to mix with and retain air and oxygen in the fluid, which can adversely affect the thermal properties of the fluid and cause problems in the thermal system. Furthermore, copper(II) oxide nanoparticles tend to aggregate and / or adhere to the fluid's container in a thermal system, potentially causing obstruction and fouling of the fluid's flow in the system. Furthermore, commercially available dark-colored nanofluids are less desirable than the lighter-colored fluids of the present application. Summary of the Invention [Problem to be solved by the invention]

[0004]

[0004] Therefore, there is currently a need for commercially viable nanofluids that have effective thermal properties, are relatively stable in use, and are capable of being mass-produced. This disclosure describes improvements over these prior art. [Means for solving the problem]

[0005] overview In one embodiment, in accordance with the principles of the present disclosure, the heat transfer mixture is represented by the equation: 1=Vpg / Vnf+Vw / Vnf+Vpw / Vnf+Vsf / Vnf+Vbs / Vnf+Vac / Vnf+Vci / Vnf. Vnf is the volume of nanofluid. Vpg is the volume of propylene glycol. Vw is the volume of water. Vpw is the volume of nanopowder. Vsf is the volume of surfactant. Vbs is the volume of base additive. Vac is the volume of acid additive. Vci is the volume of corrosion inhibitor.

[0006] In one embodiment, in accordance with the principles of the present disclosure, a heat transfer mixture includes or consists of propylene glycol, water, a nanopowder including Al2O3, a surfactant, a base additive, an acid additive, and a corrosion inhibitor. The nanopowder has a particle size of about 100 nanometers to about 600 nanometers. The heat transfer mixture includes about 1% to about 20% by volume of the nanopowder. The heat transfer mixture includes about 0.1% to about 3% by volume of the surfactant. The heat transfer mixture has a pH of about 8.5 to about 12.

[0007] In one embodiment, in accordance with the principles of the present disclosure, a heat transfer mixture comprises or consists of about 30% to about 70% by volume propylene glycol, about 30% to about 70% by volume water, about 1.0% to about 20% by volume of a nanopowder comprising Al2O3, about 0.1% to about 3% by volume of a surfactant, about 1.0% to about 10% by volume of a base additive, about 1.0% to about 10% by volume of an acid additive, and about 0.001% to about 1.0% by volume of a corrosion inhibitor. The nanopowder has a particle size of about 100 nanometers to about 600 nanometers. The heat transfer mixture has a pH of about 10.0.

[0008] In one embodiment, in accordance with the principles of the present disclosure, the heat transfer mixture is represented by the equation: 1 = Vpg / Vnf + Vw / Vnf + Vpw / Vnf + Vsf / Vnf + Vbs / Vnf. Vnf is the volume of nanofluid. Vpg is the volume of propylene glycol. Vw is the volume of water. Vpw is the volume of nanopowder. Vsf is the volume of surfactant. Vbs is the volume of base additive.

[0009] In one embodiment, in accordance with the principles of the present disclosure, a heat transfer mixture includes or consists of propylene glycol, water, a nanopowder including Al2O3, a surfactant, and a base additive. The nanopowder has a particle size of about 100 nanometers to about 600 nanometers. The heat transfer mixture includes about 1% to about 20% by volume of the nanopowder. The heat transfer mixture includes about 1% to about 3% by volume of the surfactant. The heat transfer mixture has a pH greater than 8.5.

[0010] In one embodiment, in accordance with the principles of the present disclosure, a heat transfer mixture comprises or consists of about 25% to about 50% by volume propylene glycol, about 30% to about 70% by volume water, about 1.0% to about 20% by volume of a nanopowder comprising Al2O3, about 0.1% to about 3% by volume of a surfactant, and about 1.0% to about 10% by volume of a base additive. The nanopowder has a particle size of about 100 nanometers to about 600 nanometers. The heat transfer mixture has a pH of about 10.0.

[0011] In one embodiment, in accordance with the principles of the present disclosure, the heat transfer mixture is represented by the equation: 1=Veg / Vnf+Vw / Vnf+Vpw / Vnf+Vsf / Vnf+Vbs / Vnf+Vac / Vnf+Vci / Vnf. Vnf is the volume of nanofluid. Veg is the volume of ethylene glycol. Vw is the volume of water. Vpw is the volume of nanopowder. Vsf is the volume of surfactant. Vbs is the volume of base additive. Vac is the volume of acid additive. Vci is the volume of corrosion inhibitor.

[0012] In one embodiment, in accordance with the principles of the present disclosure, a heat transfer mixture includes or consists of ethylene glycol, water, a nanopowder including Al2O3, a surfactant, a base additive, an acid additive, and a corrosion inhibitor. The nanopowder has a particle size of about 100 nanometers to about 600 nanometers. The heat transfer mixture includes about 10% to about 20% by volume of the nanopowder. The heat transfer mixture includes about 0.1% to about 3% by volume of the surfactant. The heat transfer mixture has a pH greater than 8.5.

[0013] In one embodiment, in accordance with the principles of the present disclosure, a heat transfer mixture comprises or consists of about 25% to about 50% by volume ethylene glycol, about 30% to about 70% by volume water, about 1.0% to about 20% by volume of a nanopowder comprising Al2O3, about 0.1% to about 3% by volume of a surfactant, about 0% to about 10% by volume of a base additive, about 1% to about 10% by volume of an acid additive, and about 0.001% to about 1.0% by volume of a corrosion inhibitor. The nanopowder has a particle size of about 100 nanometers to about 600 nanometers. The heat transfer mixture has a pH of about 10.0.

[0014] In one embodiment, in accordance with the principles of the present disclosure, the heat transfer mixture is represented by the formula: 1 = Veg / Vnf + Vw / Vnf + Vpw / Vnf + Vsf / Vnf + Vac / Vnf. Vnf is the volume of nanofluid. Veg is the volume of ethylene glycol. Vw is the volume of water. Vpw is the volume of nanopowder. Vsf is the volume of surfactant. Vac is the volume of acid additive.

[0015] In one embodiment, in accordance with the principles of the present disclosure, a heat transfer mixture includes or consists of ethylene glycol, water, a nanopowder including Al2O3, a surfactant, and an acid additive. The nanopowder has a particle size of about 100 nanometers to about 600 nanometers. The heat transfer mixture includes about 1% to about 20% by volume of the nanopowder. The heat transfer mixture includes about 0.1% to about 3% by volume of the surfactant. The heat transfer mixture has a pH of about 8.5 to about 12.0.

[0016] In one embodiment, in accordance with the principles of the present disclosure, a heat transfer mixture comprises or consists of about 25% to about 50% by volume ethylene glycol, about 30% to about 70% by volume water, about 1.0% to about 20% by volume of a nanopowder comprising Al2O3, about 0.1% to about 3% by volume of a surfactant, and about 0% to about 10% by volume of an acid additive. The nanopowder has a particle size of about 100 nanometers to about 600 nanometers. The heat transfer mixture has a pH of about 10.0.

[0017] BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present disclosure will become more readily apparent from the detailed description taken in conjunction with the following drawings. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a graph illustrating performance characteristics of heat transfer mixtures according to the principles of the present disclosure. [Figure 2]

[0019] 1 is a graph illustrating performance characteristics of heat transfer mixtures according to principles of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0019]

[0020] Like reference numbers refer to like parts throughout the figures.

[0020] Detailed Description

[0021] The present disclosure will be more readily understood by reference to the following detailed description of the disclosure in conjunction with the accompanying drawing figures, which form a part of this disclosure. It should be understood that the present disclosure is not limited to the specific devices, methods, conditions, or parameters described and / or illustrated herein, and that the terminology used herein is for the purpose of describing particular embodiments by way of example only, and is not intended to limit the present disclosure as claimed. Also, as used herein, including the appended claims, the singular forms "a," "an," and "the" include the plural, and reference to a particular numerical value includes at least that particular value unless the context clearly dictates otherwise. Ranges can be expressed herein as "about" or "approximately" from one particular value and / or to "about" or "approximately" another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to another particular value. Similarly, when values ​​are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another embodiment. Ranges disclosed herein include any upper limit of that range and any lower limit of that range. It should also be understood that all spatial references, such as horizontal, vertical, top, upper, lower, bottom, left and right, are for illustrative purposes only and can be varied within the scope of this disclosure. For example, references to "upper" and "lower" are relative to one another and are used only in that context, and are not necessarily "superior" and "inferior."

[0021]

[0022] The following discussion includes a description of heat transfer mixtures in accordance with the principles of the present disclosure. Alternative embodiments are also disclosed. Reference will now be made in detail to exemplary embodiments of the present disclosure.

[0022]

[0023] The present disclosure relates to formulations, processes, and applications for nanofluids having aluminum oxide nanoparticles with selected specifications for size characteristics and morphology and the ability to stably suspend in a base fluid having a specific chemical composition. In some embodiments, a solid phase is dispersed in the liquid. The solid phase is made up of clusters with dimensions such that phonon scattering that can occur at the liquid-solid interface is avoided. The heat transfer mixtures of the present disclosure are formulated and processed to maximize the heat transfer capabilities of the nanofluids with the above in mind. In some embodiments, the heat transfer mixtures of the present disclosure are concentrated nanofluids having about 1% to about 20% nanoparticles by volume, which can be introduced into thermal systems with an improved solution for delivering existing heat transfer fluids into the thermal system.

[0023]

[0024] Nanofluids are heterogeneous suspensions or mixtures containing two phases, a solid and a liquid, where the dimensions of the solid component in the suspension are on the order of nanometers. The two phases of the suspension can also be separated by mechanical methods because the materials used to form the heterogeneous mixture or suspension do not change their structure as they would in a solution, for example.

[0024]

[0025] The presence of aluminum oxide nanoparticles endows the nanofluid with suitable thermal and hydrodynamic properties compared to the base fluid, such as thermal conductivity, heat capacity, viscosity, density, and electrical conductivity.

[0025]

[0026] In many nanofluids known in the prior art, the solid-phase nanoparticles tend to settle due to gravity. This is a phenomenon with several consequences, as it reduces the volume concentration of nanoparticles in the nanofluid, which can lead to unexpected thermal and fluid properties. Furthermore, in unstable nanofluids, particles tend to accumulate in the pipes through which the nanofluid is introduced, causing clogging and therefore obvious problems in certain applications.

[0026]

[0027] Another phenomenon observed in nanofluids known in the prior art is the tendency of nanopowders to form clusters or agglomerates (solids made up of a combination of different nanometer particles) with dimensions substantially larger than the individual particles. This phenomenon has adverse effects, since it changes the properties of the nanofluid, increasing the tendency for sedimentation and significantly increasing the wear of the fluid, which can lead to the failure of certain components of the system.

[0027]

[0028] The heat transfer mixtures of the present disclosure are configured to have high thermal conductivity, higher density and heat capacity, resulting in nanofluids with higher heat exchange capacity, and are stable nanofluids whose solid phase does not tend to separate from the liquid phase or deposit on pipe surfaces in the system.

[0028]

[0029] In some embodiments, the heat transfer mixture of the present disclosure includes water, propylene glycol, and ethylene glycol as the base fluid, along with a surfactant additive to provide a stable suspension of the nanoparticles.

[0029]

[0030] The physical variables of the suspension that are fundamental to know for the optimization of the stabilization process are the pH of the suspension, the zeta potential of the suspension, the hydrophilic-hydrophobic balance (HLB) and the specific surface area (SSA) of the nanoparticles.

[0030]

[0031] Particles dispersed in a liquid typically develop an electrostatic charge on their surface, which generates an electric field that contributes to the redistribution of ions around the nanoparticle surface, increasing the concentration of ions with a charge opposite to that of the particle surface.

[0031]

[0032] This charge distribution creates an electric potential called the zeta potential, which can vary with distance from the particle. When two particles approach each other so closely that their double layers overlap, they repel each other with an electrostatic force whose strength is determined by the zeta potential, while simultaneously being attracted to each other due to the well-known van der Waals attractive force. If the zeta potential is too low, the repulsive force is not strong enough to overcome the van der Waals attractive force between the particles, and the particles begin to aggregate, destabilizing the suspension. When surfactants are added to aqueous suspensions, the high zeta potential instead prevents aggregation and maintains uniform dispersion. Surfactant molecules interpose themselves on the separation interface between the liquid and solid phases, with the polar portion facing toward the liquid phase and the polar portion facing toward the solid phase.

[0032]

[0033] In some embodiments, the heat transfer mixture of the present disclosure is a two-phase mixture consisting of a liquid fraction and a solid fraction, comprising aluminum oxide nanoparticles, purified water, propylene glycol, ethylene glycol, a polar nonionic surfactant, an anionic surfactant, a nonpolar surfactant, and sodium hydroxide.

[0033]

[0034] In some embodiments, the disclosed heat transfer mixture is a stable suspension with an appropriate concentration of nanoparticles, up to about 20% by volume. This can be diluted up to 1:20 to achieve the desired system fluid. Despite the dilution, the nanofluid is stable and contains enough additives to prevent corrosion and maintain a stable suspension for the final system purpose. In some embodiments, the disclosed heat transfer mixture exhibits stability for at least 1680 hours. In particular, increased thermal conductivity is achieved by adding high concentrations of nanofluid to base heat transfer fluids composed of water, water and propylene glycol, or ethylene glycol. For example, increased thermal conductivity of a base fluid composed of a 60:40 volumetric concentration of water and propylene glycol is achieved by adding high concentrations of stable nanofluid. In practice, with a 2% nanofluid concentration and 40% propylene glycol by volume in the system fluid, an increase in thermal conductivity of 15% to 17% is achieved. FIG. 1 shows the increase in thermal conductivity obtained by adding nanofluid to a base fluid composed of water and propylene glycol in a volumetric concentration of 60:40.

[0034]

[0035] In some embodiments, the heat transfer mixture of the present disclosure is a deliberately suspended mixture of nanometer-sized solid particles in a base fluid. By suspending small solid particles in the energy transfer fluid, their thermal conductivity can be improved, the convective heat transfer in a closed-loop circulating water system can be increased, and the energy demand can be reduced, thereby obtaining an effective and innovative method for significantly improving the heat transfer characteristics. The heat transfer mixture of the present disclosure can be used in various industrial and commercial HVAC systems and related components such as coolers, heat exchangers, boilers, and energy recovery units. The heat exchanger has a size adapted to a specific approach temperature. The lower the approach operating temperature, the larger the heat exchanger. In fact, the specific surface area of the heat exchanger is determined by the temperature difference between the two heat fluids. The surface area S of the heat exchanger required to exchange the total heat quantity Qtot at time Δt is also influenced by the fluids involved and the material properties of the exchanger surface exposed to deterioration over time. With the heat transfer mixture of the present disclosure, the thermal conductivity and mass flow rate of the system fluid increase, so the heat transfer between the air and the heat fluid increases, thereby enhancing the heat exchanger performance.

[0035]

[0036] In some embodiments, the heat transfer mixture of the present disclosure comprises aluminum oxide (Al2O3) [10 - 20% by volume] and a base fluid composed of water [15% - 90%] + propylene glycol or ethylene glycol [75% - 0%]. The amount of surfactant ranges from 2.0% to 4.0% by weight of the amount of nanoparticles. In terms of volume, this is approximately 0.1% to about 3% of the volume of the nanofluid in the mixture. The size distribution curve of the clusters of nanoparticles needs to have at least 50% of the volume of nanoparticles with diameters in the range of 100 nm < D < 600 nm. Figure 2 shows the size distribution curve of the clusters of nanoparticles used in the heat transfer mixture of the present disclosure.

[0036]

[0037] In some embodiments, in order to maintain the nanofluid stably by adding a surfactant, the following conditions are used in the formulation as a function of the amount of glycol and the nanoparticle concentration: 1 = a pg + b w + c np + dsf +e bs +f ac +g ci The parameter range is 0.293 pg <0.488;0.354 w <0.683;0.01 <c np <0.2;0.0012 <d sf <0.0234;0.013 <e bs <0.068;0.013 <f ac <0.068; and 0.0002 <g ci <0.001. The ratios of these variables are as follows: pg =Vpg / Vnf;b w =Vw / Vnf;c np =Vpw / Vnf;d sf =Vsf / Vnf;e bs =Vbs / Vnf;f ac =Vac / Vnf; and g ci = Vci / Vnf. These variables are defined as follows: Vnf = volume of nanofluid; Vpg = volume of propylene glycol; Vw = volume of water; Vpw = volume of nanopowder; Vsf = volume of surfactant; Vbs = volume of base; Vac = volume of acid. In some embodiments, the heat transfer mixture includes ethylene glycol instead of or in addition to propylene glycol. In some embodiments, the heat transfer mixture is free of base and consists of propylene glycol or ethylene glycol, water, nanopowder, surfactant, acid, and corrosion inhibitor. In some embodiments, the heat transfer mixture is free of base and acid and consists of propylene glycol or ethylene glycol, water, nanopowder, surfactant, and corrosion inhibitor. In some embodiments, the heat transfer mixture is free of acid and consists of propylene glycol or ethylene glycol, water, nanopowder, surfactant, base, and corrosion inhibitor.

[0037]

[0038] ​​In some embodiments, the heat transfer mixture of the present disclosure is produced by adding a surfactant followed by a milling step; this is a cold milling process, so the surfactant is not affected by localized high temperatures due to friction. A fluidizer is used instead of sonication, which is a mechanical process in which the nanofluid is subjected to very high shear rates. During this process, the fluid reaches velocities of up to 400 m / s and passes through diamond-coated microchannels, which reduces the clusters to the desired size.

[0038]

[0039] In some embodiments, the surfactant is a sodium salt solution of polyaminopolyether methylene phosphonic acid [CAS:130668-24-5], and the concentration of the surfactant based on the volume of the nanofluid is about 1% to about 3% by volume. In some embodiments, the surfactant is an anionic surfactant, such as, for example, the anionic surfactants listed below. [ka]

[0039]

[0040] In some embodiments, the surfactant includes nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants, as well as blends thereof. Suitable nonionic surfactants include, but are not limited to, alkyl polyglycosides, sorbitan esters, methyl glucoside esters, ethoxylated amines, ethoxylated diamines, polyglycerol esters, ethoxylated alkyls, polypropoxylated and / or polyethoxylated alcohols. Suitable anionic surfactants are selected from the group consisting of alkali metal alkyl sulfates, alkyl ether sulfonates, alkyl sulfonates, alkylaryl sulfonates, linear and branched alkyl ether sulfates and sulfonates, alcohol polypropoxylated sulfates, alcohol polyethoxylated sulfates, alcohol polypropoxylated polyethoxylated sulfates, alkyl disulfonates, alkylaryl disulfonates, alkyl disulfates, alkyl sulfosuccinates, alkyl ether sulfates, linear or branched ether sulfates, alkali metal carboxylates, fatty acid carboxylates, and phosphate esters. Suitable cationic surfactants include, but are not limited to, arginine methyl ester, alkanolamines, and alkylenediamides. Suitable surfactants may also include surfactants containing a nonionic spacer arm central extension and an ionic or nonionic polar group. Other suitable surfactants are dimeric or gemini surfactants and cleavable surfactants.

[0040]

[0041] In some embodiments, the amount of surfactant used is optimized as a function of the weight and size distribution of the nanoparticles. In some embodiments, the surfactant comprises a heat-resistant compound (Tmax=220°C), which provides an important advantage to the process since it can be mixed before milling without causing degradation due to the high temperature of friction of the milling media. Having a surfactant included during the milling process optimizes the process by improving the dispersant effect on the nanopowder.

[0041]

[0042] In some embodiments, the nanoparticles are clusters in the 100-600 nm range. The solid phase is made of clusters with dimensions that avoid phonon scattering that can occur at the liquid-solid interface. This condition optimizes heat transfer efficiency and thermal wave propagation. In some embodiments, to achieve this distribution of clusters, 0.3 mm grinding media and a 4500 rpm mill are used for 3 hours.

[0042]

[0043] In some embodiments, the heat transfer mixture of the present disclosure is produced using a fluidizer instead of sonication. This is a mechanical process in which the nanofluid is subjected to very high shear rates. The fluid, under pressure at 2000 bar, reaches velocities of up to 400 m / s and passes through diamond-coated microchannels, thereby reducing the clusters to the desired size. A cryogenic grinder is used to avoid temperature increases during the process due to friction with the grinding media. Sodium hydroxide is used to adjust the pH to 10 to optimize the solution for sedimentation. pH=10 is the chemical condition for nanofluids that results in a zeta potential of over 25 mV, which resists nanoparticle sedimentation.

[0043]

[0044] Using a fluidizer, pressures of 2000 bar and suitable shear rates can be achieved. Fluidizers also increase the volumetric flow rate of the process, which is much more feasible compared to sonication processes. Cold grinding avoids the decomposition of surfactants inside the chamber during grinding. Heat-resistant surfactants are more suitable to avoid additive degradation during the grinding process, where high-temperature friction occurs.

[0044]

[0045] In some embodiments, the heat transfer mixture of the present disclosure includes nanoparticles that form clusters or agglomerates, i.e., particles that consist of a large number of nanometer particles with dimensions substantially larger than a single particle. This phenomenon was previously thought to be detrimental because clusters were thought to only increase the likelihood of settling. However, it has been discovered that the use of clusters or agglomerates of nanoparticles within a certain size range in conjunction with a surface-active additive can help improve the effective thermal properties of the heat transfer mixture.

[0045]

[0046] In some embodiments, the heat transfer mixtures of the present disclosure result in stable nanofluids whose solid phase does not tend to separate from the liquid phase and deposit at the bottom of the container in which the nanofluid is stored or in the pipes of the system in which the nanofluid is utilized.

[0046]

[0047] In some embodiments, the solid phase of the heat transfer mixture of the present disclosure comprises aluminum oxide nanopowder. In some embodiments, the liquid phase of the heat transfer mixture comprises water and a surfactant. In particular, as explained in detail below, the properties that determine the heat exchange capacity and stability of the nanofluid are the morphological, dimensional, and structural properties of the solid components and the presence and concentration of chemical additives in the liquid phase. Factors that affect the stabilization of the suspension against nanoparticle aggregation are the pH of the suspension, interfacial tension, and the surface electrostatic charge of the nanoparticles.

[0047]

[0048] Generally, particles dispersed in a liquid have an electrostatic charge on their surface, which determines the electric field responsible for the redistribution of ions in the space surrounding the particle. This increases the concentration of ions of opposite charge to that on the particle surface. In particular, the liquid layer surrounding a particle consists of two layers: an inner zone (the Stern layer) with ions strongly bound to the particle, and an outer zone (the Gouy-Chapman or diffuse layer) with weaker electrostatic interactions. These two zones constitute a double electric layer around each particle. Within the diffuse layer, two zones can be defined, separated by a plane that is the shear plane. As the particle moves, ions in the diffuse layer closer to the particle than the shear plane move with the particle, while ions beyond the shear plane are constantly replaced by other ions present in the liquid.

[0048]

[0049] This charge distribution determines an electric potential (the zeta potential) that can vary with particle distance. When two particles come close enough that their double layers overlap, they repel each other with an electrostatic force whose strength is determined by the zeta potential, and at the same time are attracted to each other due to the well-known van der Waals attractive force. If the zeta potential is too low, the repulsive force is not strong enough to overcome the van der Waals attractive force between the particles, and they begin to aggregate, thereby destabilizing the suspension. A high zeta potential avoids aggregation and maintains the uniformity of the dispersion.

[0049]

[0050] Another condition that influences suspension stability is the wetting state of the solid particles, i.e., the ability of a liquid to distribute on the solid surface, which is determined by the surface tension of the liquid and solid phases.

[0050]

[0051] In fact, when a liquid and a solid come into contact, interfacial tension occurs due to the interaction between these phases. If we assume that a liquid drop is in contact with a solid surface, the contour of the liquid portion placed on the solid surface forms an angle Θ, which is the wetting angle, which is greater or less than 90° depending on whether cohesive forces prevail between the liquid molecules or whether adhesive forces prevail between the molecules of two different solid and liquid phases. The angle Θ is determined by the following relationship: cos(Θ)=(YS-ySL) / yL(1) where yS, ySL, and yL are the surface tensions between the solid and air, between the solid and liquid (interfacial tension), and between the liquid and air, respectively. From (1), we can see how the wettability of a liquid can be increased by decreasing the surface tension of the liquid.

[0051]

[0052] To achieve this result within the suspension, and thus reduce the tendency of particles to aggregate, the inventors introduce a substance that affects the liquid-solid surface tension (a surfactant). Surfactants are a class of organic compounds that contain a hydrophilic part (polar, having an affinity for water, making them soluble) and a hydrophobic part (non-polar, having an affinity for oily substances, making them insoluble in water). By adding a surfactant to an aqueous suspension, the surfactant molecules themselves align themselves at the separation interface between the liquid and solid phases, with the polar part facing toward the liquid phase and the non-polar part facing toward the solid phase (or the gas phase in the case of a liquid-air separation interface).

[0052]

[0053] To control suspension stability, it is necessary to intervene in the electrostatic charge around the particles and the interfacial tension between the solid and liquid phases.

[0053]

[0054] In some embodiments, the solid phase of the heterogeneous mixture comprises aluminum oxide nanoparticles of a particular morphology and size. In some embodiments, the solid phase dispersed in the liquid is comprised of nanometer-sized particles (nanopowder or nanoparticles) having an average size of about 100 nanometers to about 600 nanometers. In some embodiments, the solid phase dispersed in the liquid is comprised of nanometer-sized particles (nanopowder or nanoparticles) having an average size of about 200 nanometers to about 500 nanometers. In some embodiments, the solid phase dispersed in the liquid is comprised of nanometer-sized particles (nanopowder or nanoparticles) having an average size of about 300 nanometers to about 400 nanometers. In some embodiments, the solid phase dispersed in the liquid is comprised of nanometer-sized particles (nanopowder or nanoparticles) having an average size of about 400 nanometers to about 600 nanometers. In some embodiments, the solid phase dispersed in the liquid is comprised of nanometer-sized particles (nanopowder or nanoparticles) having an average size of about 100 nanometers to about 600 nanometers. In some embodiments, the solid phase dispersed in the liquid is comprised of nanometer-sized particles (nanopowder or nanoparticles) having an average size between about 300 nanometers and about 600 nanometers. In some embodiments, the solid phase dispersed in the liquid is comprised of nanometer-sized particles (nanopowder or nanoparticles) having an average size between 100 nanometers and 600 nanometers. In some embodiments, the solid phase dispersed in the liquid is comprised of nanometer-sized particles (nanopowder or nanoparticles) having an average size between 300 nanometers and 600 nanometers.

[0054]

[0055] In some embodiments, the concentration of the nanopowder or nanoparticles is between about 0.1% by volume of the nanofluid and about 50% by volume of the nanofluid. In some embodiments, the concentration of the nanopowder or nanoparticles is between about 1.0% by volume of the nanofluid and about 40% by volume of the nanofluid. In some embodiments, the concentration of the nanopowder or nanoparticles is between about 2% by volume of the nanofluid and about 30% by volume of the nanofluid. In some embodiments, the concentration of the nanopowder or nanoparticles is between about 3% by volume of the nanofluid and about 30% by volume of the nanofluid. In some embodiments, the concentration of the nanopowder or nanoparticles is between about 4% by volume of the nanofluid and about 30% by volume of the nanofluid. In some embodiments, the concentration of the nanopowder or nanoparticles is between about 5% by volume of the nanofluid and about 30% by volume of the nanofluid. In some embodiments, the concentration of the nanopowder or nanoparticles is between about 6% by volume of the nanofluid and about 25% by volume of the nanofluid. In some embodiments, the concentration of the nanopowder or nanoparticles is between about 10% by volume of the nanofluid and about 20% by volume of the nanofluid. In some embodiments, the concentration of the nanopowder or nanoparticles is between 0.1% by volume of the nanofluid and 50% by volume of the nanofluid. In some embodiments, the concentration of the nanopowder or nanoparticles is between 1.0% by volume of the nanofluid and 40% by volume of the nanofluid. In some embodiments, the concentration of the nanopowder or nanoparticles is between 2% by volume of the nanofluid and 30% by volume of the nanofluid. In some embodiments, the concentration of the nanopowder or nanoparticles is between 3% by volume of the nanofluid and 30% by volume of the nanofluid. In some embodiments, the concentration of the nanopowder or nanoparticles is between 4% by volume of the nanofluid and 30% by volume of the nanofluid. In some embodiments, the concentration of the nanopowder or nanoparticles is between 5% by volume of the nanofluid and 30% by volume of the nanofluid. In some embodiments, the concentration of the nanopowder or nanoparticles is between 6% by volume of the nanofluid and 25% by volume of the nanofluid. In some embodiments, the concentration of the nanopowder or nanoparticles is between 10% by volume of the nanofluid and 20% by volume of the nanofluid.

[0055]

[0056] In some embodiments, the heat transfer mixture of the present disclosure is a two-phase mixture composed of a liquid fraction and a solid fraction, the liquid fraction including water, propylene glycol or ethylene glycol, a surfactant, a pH adjusting additive at concentrations that maximize the zeta potential and minimize the interfacial tension between the solid and liquid phases, and a corrosion inhibitor.

[0056]

[0057] In some embodiments, the mass ratio between the amount of surfactant present in the liquid phase and the amount of nanopowder is about 2% to about 4%. In some embodiments, the mass ratio between the amount of surfactant present in the liquid phase and the amount of nanopowder is about 2.5% to about 3.5%. In some embodiments, the mass ratio between the amount of surfactant present in the liquid phase and the amount of nanopowder is about 3%. In some embodiments, the mass ratio between the amount of surfactant present in the liquid phase and the amount of nanopowder is between 3.5%.

[0057]

[0058] In some embodiments, the surfactant concentration is from about 0.1% based on the total volume of the nanofluid to about 3% based on the total volume of the nanofluid. In some embodiments, the surfactant concentration is from about 0.5% based on the total volume of the nanofluid to about 2.5% based on the total volume of the nanofluid. In some embodiments, the surfactant concentration is from about 1% based on the total volume of the nanofluid to about 2% based on the total volume of the nanofluid.

[0058]

[0059] In some embodiments, the nanoparticles in the nanofluid have a regular morphology, particularly a spherical morphology, which can optimize heat exchange capacity and reduce the tendency of the nanoparticles to become trapped on the surfaces of the pipe. In some embodiments, the nanoparticles in the nanofluid have an irregular morphology. In some embodiments, the nanoparticles in the nanofluid are in the form of clusters.

[0059]

[0060] In some embodiments, the heat transfer mixture of the present disclosure has a viscosity of 1 g / cm 3 ~1.65g / cm 3In some embodiments, the heat transfer mixture of the present disclosure has a dynamic viscosity at 20°C of 1 cps to 30 cps. In some embodiments, the heat transfer mixture of the present disclosure at a 2% nanoparticle concentration has a thermal conductivity increase (at 20°C) of 15% to 17%, and the increase in thermal conductivity is linear with the concentration in the heat transfer mixture.

[0060]

[0061] In some embodiments, nanofluid preparation involves mixing water, nanoparticles, a surfactant, and propylene glycol or ethylene glycol; grinding in a high-speed mill; and fluidizing. In the mixing step, tap water, a powder containing surfactant, propylene glycol or ethylene glycol, and nanoparticles are mixed in amounts to achieve the desired volumetric solids percentage. This mixing is performed using a cryogenic grinder, which is maintained at a low temperature to avoid temperature increases due to friction with the grinding media. The solution is milled using a continuous mill consisting of a jug containing zirconia particles. Using this method, nanoparticle clusters are not crushed. Particle size = 0.3 mm to 1 mm, determined by the mixture concentration. After milling, the nanofluid is collected at the outlet in a continuous fluidizer. The fluidizer utilizes a mechanical process that subjects the nanofluid to very high shear rates. During this process, the fluid reaches velocities of up to 400 m / s and passes through diamond-coated microchannels, where the clusters are reduced to a selected size. In some embodiments, sonication is not involved in the preparation of nanofluids. In some embodiments, sodium hydroxide is used to adjust the pH of the nanofluid to 10.0.

[0061]

[0062] In some embodiments, the liquid component of the heat transfer mixture of the present disclosure does not contain any additives, such as, for example, base additives, acid additives, or corrosion inhibitors. In some embodiments, the liquid component of the heat transfer mixture of the present disclosure includes a base as the only additive. In some embodiments, the liquid component of the heat transfer mixture of the present disclosure includes an acid as the only additive. In some embodiments, the liquid component of the heat transfer mixture of the present disclosure includes a corrosion inhibitor as the only additive. In some embodiments, the base additive includes sodium hydroxide [NaOH], potassium hydroxide [KOH], or calcium hydroxide [Ca(OH)], which is used to increase the pH of the product after the preparation process, because a pH of 10 is the necessary basic level to ensure the stability of nanoparticles in suspension. Indeed, the "zeta potential" relates to the field of electrochemistry surrounding nanoparticles in a fluid and becomes more pronounced when the pH is above 8.5. In some embodiments, acid additives, including hydrochloric acid, acetic acid, and / or phosphoric acid, are used to form nanofluids with ethylene glycol because in this case the pH is above 10 and an acid is needed to lower the pH to 10 for a stable nanofluid suspension. In some embodiments, corrosion inhibitors, including molybdate anions, calcium nitrite, zinc phosphate, chromate, and / or lanthanide compounds, are used to prevent corrosion between the nanoparticles and the metal surfaces of the system in which they are introduced. The inhibitors are useful for avoiding pitting caused by deposition and contact between the nanoparticles and the metal surfaces.

[0062]

[0063] In some embodiments, the liquid component of the heat transfer mixture of the present disclosure includes one or more additives to achieve other desired chemical and physical properties and characteristics. In some embodiments, the additives include, in addition to the aforementioned components, a base additive, an acid additive, and / or a corrosion inhibitor. That is, the heat transfer mixture of the present disclosure can include, in addition to water, nanoparticles, a surfactant, and propylene glycol and / or ethylene glycol, a base additive, an acid additive, and / or a corrosion inhibitor. In some embodiments, the base additive, the acid additive, and / or the corrosion inhibitor are mixed with the nanoparticles, the surfactant, and the propylene glycol and / or ethylene glycol during the mixing step.

[0063]

[0064] In some embodiments, the base additive is configured to increase the pH of the nanofluid. In some embodiments, the heat transfer mixture includes propylene glycol, and the surfactant results in a fluid with a pH less than 7. Therefore, a base additive, such as sodium hydroxide, is used to increase the pH to 10. In some embodiments, the base additive includes KOH, NaOH, NaHCO3, Ca(OH)2, K2CO3, and / or Na2CO3. In some embodiments, the acid additive is configured to decrease the pH of the nanofluid. In some embodiments, the heat transfer mixture includes ethylene glycol, and the fluid results in a pH greater than 10. Therefore, an acid is used to decrease the pH to 10 and mitigate corrosion. In some embodiments, the acid additive includes hydrochloric acid, acetic acid, and / or phosphoric acid. In some embodiments, the corrosion inhibitor is configured to prevent corrosion of the nanoparticles. In some embodiments, the corrosion inhibitor includes molybdate anion, calcium nitrite, zinc phosphate, chromate, and / or lanthanide compounds, and is used to prevent corrosion between the nanoparticles and the metal surfaces of the system in which they are introduced. The inhibitor is useful to avoid the pitting phenomenon caused by deposition and contact between the nanoparticles and the metal surface.

[0064]

[0065] In some embodiments, the base additive includes triazoles such as tolyltriazole and benzotriazole, aspartic acid, sebacic acid, borax, molybdates such as molybdenum oxide and sodium molybdate dihydrate, nitrites, amine-based compounds such as ethylenediamine, propylenediamine, morpholine, short chain aliphatic dicarboxylic acids such as maleic acid, succinic acid, and adipic acid, thiazoles such as mercaptobenzothiazole, thiadiazoles such as 2-mercapto-5-hydrocarbylthio-1,3,4-thiadiazole, 2-mercapto-5-hydrocarbyldithio-1,3,4-thiadiazole, 2,5-bis(hydrocarbylthio)-1,3,4-thiadiazole, and 2,5-(bis)hydrocarbyldithio)-1,3,4-thiadiazole, sulfonates, imidazolines, or combinations of two or more thereof.

[0065]

[0066] In some embodiments, the liquid component of the heat transfer mixture of the present disclosure does not include propylene glycol or ethylene glycol. In such embodiments, the liquid component of the heat transfer mixture of the present disclosure consists of water. In this embodiment, the heat transfer mixture is represented by the equation: 1 = Vw / Vnf + Vpw / Vnf + Vsf / Vnf + Vbs / Vnf + Vac / Vnf + Vci / Vnf, where Vnf is the volume of nanofluid, Vw is the volume of water, Vpw is the volume of nanopowder, Vsf is the volume of surfactant, Vbs is the volume of base additive, Vac is the volume of acid additive, and Vci is the volume of corrosion inhibitor. In one embodiment, the surfactant is HEDP / PBTC / PCA-etidronic acid / phosphonobutane-tricarboxylic acid / phosphino-carboxylic acid.

[0066]

[0067] The heat transfer mixtures of the present disclosure have a wide range of applications, including HVAC, power generation, chemical processing, and data center cooling. With respect to HVAC, the heat transfer mixtures can be used in a variety of industrial and commercial HVAC systems and related component applications, such as chillers, heat exchangers, boilers, and energy recovery units. In any hydronic heating and / or cooling system, the heat transfer mixtures reduce heat exchanger approach temperatures, increasing heat transfer efficiency and reducing energy losses.

[0067]

[0068] It will be understood that various modifications to the embodiments disclosed herein are possible. Accordingly, the above description should not be construed as limiting, but merely as examples of various embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.

Claims

1. formula: 1=Vpg / Vnf+Vw / Vnf+Vpw / Vnf+Vsf / Vnf+Vbs / Vnf+Vac / Vnf+Vci / Vnf (where Vnf is the volume of the nanofluid, Vpg is the volume of propylene glycol; Vw is the volume of water, Vpw is the volume of the nanopowder; Vsf is the volume of the surfactant; Vbs is the volume of the base additive; Vac is the volume of the acid additive; Vci is the volume of the corrosion inhibitor A heat transfer mixture consisting of a nanofluid represented by: The surfactant is a heat transfer mixture consisting of etidronic acid (HEDP), phosphonobutane-tricarboxylic acid (PBTC) and phosphino-carboxylic acid (PCA).

2. 2. The heat transfer mixture of claim 1, wherein 29.3%<Vpg / Vnf<48.8%.

3. 2. The heat transfer mixture of claim 1, wherein 35.4%<Vw / Vnf<68.3%.

4. 2. The heat transfer mixture of claim 1, wherein 1%<Vpw / Vnf<20%.

5. 2. The heat transfer mixture of claim 1, wherein 0.12%<Vsf / Vnf<2.34%.

6. 2. The heat transfer mixture of claim 1, wherein 1.3%<Vbs / Vnf<6.8%.

7. 2. The heat transfer mixture of claim 1, wherein 1.3<Vac / Vnf<6.

8.

8. 2. The heat transfer mixture of claim 1, wherein 0.02<Vci / Vnf<0.

1.

9. 29.3%<Vpg / Vnf<48.8%; 35.4%<Vw / Vnf<68.3%; 1%<Vpw / Vnf<20%; 0.12%<Vsf / Vnf<2.34%; 1.3%<Vbs / Vnf<6.8%; 1.3<Vac / Vnf<6.8; and 2. The heat transfer mixture of claim 1, wherein 0.02<Vci / Vnf<0.

1.

10. 29.3%<Vpg / Vnf<48.8%; 35.4%<Vw / Vnf<68.3%; 1%<Vpw / Vnf<20%; 0.12%<Vsf / Vnf<2.34%; 0%<Vbs / Vnf<6.8%; 0<Vac / Vnf<6.8; and 2. The heat transfer mixture of claim 1, wherein 0<Vci / Vnf<0.

1.

11. 10. The heat transfer mixture of claim 1, wherein the nanopowder is aluminum oxide.

12. 10. The heat transfer mixture of claim 1, wherein the nanopowder is aluminum oxide in the range of 100 nanometers to 600 nanometers.

13. 10. The heat transfer mixture of claim 1 having a pH of 8.5 to 12.

0.

14. 14. The heat transfer mixture of claim 13 having a pH of 10.

0.

15. propylene glycol; Water and a nanopowder comprising Al2O3; a surfactant; a base additive; an acid additive; Corrosion inhibitors and A heat transfer mixture comprising: the nanopowder has a particle size of 100 nanometers to 600 nanometers; the heat transfer mixture comprises 1% to 20% by volume of the nanopowder; the heat transfer mixture comprises 0.1% to 3% by volume of the surfactant; The heat transfer mixture has a pH greater than 8.5, The surfactant is a heat transfer mixture consisting of etidronic acid (HEDP), phosphonobutane-tricarboxylic acid (PBTC) and phosphino-carboxylic acid (PCA).

16. 5% to 75% by volume of propylene glycol; 30% to 70% by volume of water; 1.0% to 20% by volume of a nanopowder comprising Al2O3; 0.1% to 3% by volume of a surfactant; 0% to 10% by volume of a base additive; 0% to 10% by volume of an acid additive; 0.001% to 1.0% by volume of a corrosion inhibitor; A heat transfer mixture comprising: the nanopowder has a particle size of 100 nanometers to 600 nanometers; The heat transfer mixture has a pH of 10.0; The surfactant is a heat transfer mixture consisting of etidronic acid (HEDP), phosphonobutane-tricarboxylic acid (PBTC) and phosphino-carboxylic acid (PCA).

17. formula: 1=Vpg / Vnf+Vw / Vnf+Vpw / Vnf+Vsf / Vnf+Vbs / Vnf (where Vnf is the volume of the nanofluid, Vpg is the volume of propylene glycol; Vw is the volume of water, Vpw is the volume of the nanopowder; Vsf is the volume of the surfactant; Vbs is the volume of the base additive A heat transfer mixture consisting of a nanofluid represented by: The surfactant is a heat transfer mixture consisting of etidronic acid (HEDP), phosphonobutane-tricarboxylic acid (PBTC) and phosphino-carboxylic acid (PCA).

18. 18. The heat transfer mixture of claim 17, wherein 5%<Vpg / Vnf<75%.

19. 18. The heat transfer mixture of claim 17, wherein 5%<Vw / Vnf<94%.

20. 18. The heat transfer mixture of claim 17, wherein 0.1%<Vpw / Vnf<20%.

21. 18. The heat transfer mixture of claim 17, wherein 0.01%<Vsf / Vnf<3%.

22. 18. The heat transfer mixture of claim 17, wherein 0.1%<Vbs / Vnf<10%.

23. 5%<Vpg / Vnf<75%; 5%<Vw / Vnf<94%; 0.1%<Vpw / Vnf<20%; 0.01%<Vsf / Vnf<3%; and 18. The heat transfer mixture of claim 17, wherein 0.1%<Vbs / Vnf<10%.

24. propylene glycol; Water and a nanopowder comprising Al2O3; a surfactant; Base additives and A heat transfer mixture comprising: the nanopowder has a particle size of 100 nanometers to 600 nanometers; the heat transfer mixture comprises 1% to 20% by volume of the nanopowder; the heat transfer mixture comprises 0.010% to 3% by volume of the surfactant; The heat transfer mixture has a pH of 8.5 to 12; The surfactant is a heat transfer mixture consisting of etidronic acid (HEDP), phosphonobutane-tricarboxylic acid (PBTC) and phosphino-carboxylic acid (PCA).

25. 5% to 70% by volume of propylene glycol; 5% to 94% by volume of water; 1.0% to 20% by volume of a nanopowder comprising Al2O3; 0.01% to 3% by volume of a surfactant; 1.0% to 10% by volume of a base additive; A heat transfer mixture comprising: the nanopowder has a particle size of 100 nanometers to 600 nanometers; The heat transfer mixture has a pH of 10.0; The surfactant is a heat transfer mixture consisting of etidronic acid (HEDP), phosphonobutane-tricarboxylic acid (PBTC) and phosphino-carboxylic acid (PCA).

26. formula: 1=Veg / Vnf+Vw / Vnf+Vpw / Vnf+Vsf / Vnf+Vbs / Vnf+Vac / Vnf+Vci / Vnf (where Vnf is the volume of the nanofluid, V is the volume of ethylene glycol, Vw is the volume of water, Vpw is the volume of the nanopowder; Vsf is the volume of the surfactant; Vbs is the volume of the base additive; Vac is the volume of the acid additive; Vci is the volume of the corrosion inhibitor A heat transfer mixture consisting of a nanofluid represented by: The surfactant is a heat transfer mixture consisting of etidronic acid (HEDP), phosphonobutane-tricarboxylic acid (PBTC) and phosphino-carboxylic acid (PCA).

27. 27. The heat transfer mixture of claim 26, wherein 30.0%<Veg / Vnf<50.0%.

28. 27. The heat transfer mixture of claim 26, wherein 50.0%<Vw / Vnf<70.0%.

29. 27. The heat transfer mixture of claim 26, wherein 1%<Vpw / Vnf<3.0%.

30. 27. The heat transfer mixture of claim 26, wherein 0.12%<Vsf / Vnf<0.40%.

31. 27. The heat transfer mixture of claim 26, wherein 1.3%<Vbs / Vnf<2.0%.

32. 27. The heat transfer mixture of claim 26, wherein 0.0<Vac / Vnf<2.

0.

33. 27. The heat transfer mixture of claim 26, wherein 0.012<Vci / Vnf<0.

1.

34. 30%<Veg / Vnf<50.0%; 50.0%<Vw / Vnf<70.0%; 1%<Vpw / Vnf<3.0%; 0.12%<Vsf / Vnf<0.40%; 1.3%<Vbs / Vnf<2.0%; 0.0<Vac / Vnf<2.08; and 27. The heat transfer mixture of claim 26, wherein 0.02<Vci / Vnf<0.

1.

35. 35.0%<Veg / Vnf<45.0%; 55.0%<Vw / Vnf<65.0%; 1%<Vpw / Vnf<2.0%; 0.12%<Vsf / Vnf<0.40%; 1.3%<Vbs / Vnf<6.8%; 0<Vac / Vnf<2.0; and 27. The heat transfer mixture of claim 26, wherein 0.02<Vci / Vnf<0.

1.

36. 27. The heat transfer mixture of claim 26, wherein the nanopowder is aluminum oxide.

37. 27. The heat transfer mixture of claim 26, wherein the nanopowder is aluminum oxide in the range of 100 nanometers to 600 nanometers.

38. 27. The heat transfer mixture of claim 26 having a pH of 8.5 to 12.

0.

39. 27. The heat transfer mixture of claim 26 having a pH of 10.

0.

40. Ethylene glycol; Water and a nanopowder comprising Al2O3; a surfactant; a base additive; an acid additive; Corrosion inhibitors and A heat transfer mixture comprising: the nanopowder has a particle size of 100 nanometers to 600 nanometers; the heat transfer mixture comprises 10% to 20% by volume of the nanopowder; the heat transfer mixture comprises 0.4% to 3% by volume of the surfactant; The heat transfer mixture has a pH of 8.5 to 12.0; The surfactant is a heat transfer mixture consisting of etidronic acid (HEDP), phosphonobutane-tricarboxylic acid (PBTC) and phosphino-carboxylic acid (PCA).

41. 5% to 70% by volume of ethylene glycol; 5% to 94% by volume of water; 1.0% to 20% by volume of a nanopowder comprising Al2O3; 0.1% to 3% by volume of a surfactant; 1.0% to 10% by volume of a base additive; 0% to 6.8% by volume of an acid additive; 0.12% to 0.10% by volume of a corrosion inhibitor; A heat transfer mixture comprising: the nanopowder has a particle size of 100 nanometers to 600 nanometers; The heat transfer mixture has a pH of 10.0; The surfactant is a heat transfer mixture consisting of etidronic acid (HEDP), phosphonobutane-tricarboxylic acid (PBTC) and phosphino-carboxylic acid (PCA).

42. formula: 1=Veg / Vnf+Vw / Vnf+Vpw / Vnf+Vsf / Vnf+Vac / Vnf (where Vnf is the volume of the nanofluid, V is the volume of ethylene glycol, Vw is the volume of water, Vpw is the volume of the nanopowder; Vsf is the volume of the surfactant; Vac is the volume of the acid additive A heat transfer mixture consisting of a nanofluid represented by: The surfactant is a heat transfer mixture consisting of etidronic acid (HEDP), phosphonobutane-tricarboxylic acid (PBTC) and phosphino-carboxylic acid (PCA).

43. 43. The heat transfer mixture of claim 42, wherein 25%<Veg / Vnf<50%.

44. 43. The heat transfer mixture of claim 42, wherein 30%<Vw / Vnf<70%.

45. 43. The heat transfer mixture of claim 42, wherein 0.1%<Vpw / Vnf<20%.

46. 43. The heat transfer mixture of claim 42, wherein 0.01%<Vsf / Vnf<3%.

47. 43. The heat transfer mixture of claim 42, wherein 0%<Vac / Vnf<10%.

48. 25%<Veg / Vnf<50%; 30%<Vw / Vnf<70%; 0.1%<Vpw / Vnf<30%; 0.01%<Vsf / Vnf<5%; and 43. The heat transfer mixture of claim 42, wherein 0%<Vac / Vnf<10%.

49. Ethylene glycol; Water and a nanopowder comprising Al2O3; a surfactant; Acid Additives and A heat transfer mixture comprising: the nanopowder has a particle size of 100 nanometers to 600 nanometers; the heat transfer mixture comprises 10% to 20% by volume of the nanopowder; the heat transfer mixture comprises 0.1% to 3% by volume of the surfactant; The heat transfer mixture has a pH of 8.5 to 12.0; The surfactant is a heat transfer mixture consisting of etidronic acid (HEDP), phosphonobutane-tricarboxylic acid (PBTC) and phosphino-carboxylic acid (PCA).

50. 30% to 50% by volume of ethylene glycol; 50% to 70% by volume of water; 1.0% to 3.0% by volume of a nanopowder comprising Al2O3; 0.1% to 0.4% by volume of a surfactant; 0% to 2.0% by volume of an acid additive; A heat transfer mixture comprising: the nanopowder has a particle size of 100 nanometers to 600 nanometers; The heat transfer mixture has a pH of 10.0; The surfactant is a heat transfer mixture consisting of etidronic acid (HEDP), phosphonobutane-tricarboxylic acid (PBTC) and phosphino-carboxylic acid (PCA).

51. formula: 1=Vw / Vnf+Vpw / Vnf+Vsf / Vnf+Vbs / Vnf+Vac / Vnf+Vci / Vnf (where Vnf is the volume of the nanofluid, Vw is the volume of water, Vpw is the volume of the nanopowder; Vsf is the volume of the surfactant; Vbs is the volume of the base additive; Vac is the volume of the acid additive; Vci is the volume of the corrosion inhibitor A heat transfer mixture consisting of a nanofluid represented by: The surfactant is a heat transfer mixture consisting of etidronic acid (HEDP), phosphonobutane-tricarboxylic acid (PBTC) and phosphino-carboxylic acid (PCA).

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