A highly stable nanofluid fuel

Abstract

This invention discloses a highly stable nanofluid fuel, belonging to the field of engine fuel technology. The high-stability nanofluid fuel provided by this invention uses alkanes with high melting points as the solidifying agent, enabling solid-state storage at room temperature, and hydrocarbon fuels with low freezing points as the liquefying agent, achieving solid-to-liquid transformation without additional external force or heat source. This invention achieves liquefaction from storage to use through four steps: melting the solidifying agent particles, adding surfactants and high-energy solid particles to complete solidification, and then adding the liquefying agent. The preparation is simple, low-cost, and effectively improves the long-term dispersion stability of the nanofluid fuel.

Description

Technical Field

[0001] This invention belongs to the field of engine fuel technology, and in particular relates to a highly stable nanofluid fuel. Background Technology

[0002] Nanofluid fuels are novel high-density fluid fuels prepared by dispersing high-energy metal particles such as boron and aluminum in liquid fuel. They possess both high fluidity and high energy density, showing great potential to replace traditional liquid fuels as the next generation of aerospace propulsion power, and thus hold significant research and application value. Ideally, nanofluid fuels should exhibit a two-phase dispersion system where high-energy metal particles are stably suspended in liquid fuel. However, due to the significant density difference between the solid and liquid phases, and the tendency for key energetic components (nanometal particles) to aggregate, metal particle sedimentation often occurs during fuel storage. This significantly reduces the usable energy of the fuel pumped into the combustion system, substantially diminishing the energy advantages of nanofluid fuels.

[0003] Existing research on improving the stability of nanofluid fuels mainly focuses on two technical approaches: particle surface modification and base liquid gelation. Particle surface modification utilizes modifier molecules to form an adsorption layer on the particle surface, increasing steric hindrance to inhibit agglomeration and thus slowing particle settling. However, surface modification can only maintain short-term stable dispersion of the fuel, making it difficult to meet long-term storage requirements. Base liquid gelation, on the other hand, adds gelling agents to the base liquid to form a molecular network structure, increasing the base liquid viscosity and thus inhibiting the settling of metal particles. However, the addition of gelling agents alters the fuel's viscosity and other physicochemical properties and adversely affects atomization and combustion. Summary of the Invention

[0004] To address the issues of poor stability and short storage time of nanofluid fuels, this invention provides a highly stable nanofluid fuel. This fuel achieves solid-state storage at room temperature by adding high-melting-point alkanes, preserving the dispersion stability of energetic metal particles. During use, low-freezing-point hydrocarbon fuels are added, transforming it from a solid to a liquid nanofluid fuel for use. This invention utilizes solid-liquid phase change to achieve a high-energy nanofluid fuel that is stored in solid state and liquefied for use. Its physical structure ensures long-term stable storage of the fuel, and during use, no external force or heat source is required, achieving the demand for low-energy-consumption, high-response, and dispersedly stable nanofluid fuel.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a highly stable nanofluid fuel, comprising a storage solid nanofluid fuel and a liquefying agent; the storage solid nanofluid fuel comprises high-energy solid particles, a surfactant, and a curing agent.

[0006] Furthermore, by mass percentage, the highly stable nanofluid fuel comprises the following components: high-energy solid particles: 0.1%–20%, surfactant: 0.1%–2%, curing agent: 10%–50%, and the balance being liquefying agent.

[0007] Furthermore, the particle size of the stored solid nanofluid fuel is 0.1–3 mm.

[0008] Furthermore, the high-energy solid particles are selected from one or more of boron powder, aluminum powder, or magnesium powder, and the particle size of the high-energy solid particles is 1-100 nm, with a purity of 95% or higher.

[0009] Furthermore, the surfactant includes one or more of Span 85, Span 80, and Tween 85.

[0010] Furthermore, the curing agent is selected from one or more of n-octadecane, n-eicosane, n-docosahexadecane, and n-tetracosane.

[0011] The curing agent used in this invention is an alkane that is solid at room temperature, including but not limited to straight-chain or branched alkanes with C18-C28 carbon atoms and their mixtures.

[0012] Furthermore, the liquefaction agent used in this invention is a hydrocarbon fuel that is liquid at room temperature and has a low freezing point, including but not limited to aviation kerosene RP-1, RP-2, RP-3 and synthetic hydrocarbon fuels JP10 (hanging tetrahydrodicyclopentadiene) and tetracycloheptane. Hanging tetrahydrodicyclopentadiene or tetracycloheptane is preferred.

[0013] Furthermore, the preparation method of the stored solid nanofluid fuel includes the following steps: adding a surfactant to a molten curing agent, mixing it for the first time at a constant temperature, then adding high-energy solid particles, mixing it for the second time at a constant temperature, stopping heating, solidifying it into a block at room temperature, and pulverizing it to obtain the stored solid nanofluid fuel.

[0014] In the preparation of solid-state nanofluid fuels, after heating is stopped, the system achieves solid-state storage at room temperature through the three-dimensional lattice network formed by the curing agent.

[0015] Furthermore, the initial mixing temperature under constant temperature is 80°C, and the secondary mixing temperature under constant temperature is 75°C.

[0016] Secondly, the present invention provides a method for using the high-stability nanofluid fuel described above. When using the high-stability nanofluid fuel provided by the present invention, the high-stability nanofluid fuel that has solidified into a block is taken out, a liquefying agent is added, and the dissolution temperature reduction effect derived from Raoult's law is used to induce lattice defects in the curing agent, so that the system can spontaneously change from solid to liquid nanofluid fuel without external heating (ambient temperature is 15-30°C).

[0017] Compared with the prior art, the present invention has the following advantages and technical effects: (1) The high-stability nanofluid fuel provided by this invention uses alkanes with high melting points as the curing agent, enabling solid storage at room temperature. The liquefaction agent is a hydrocarbon fuel with a low freezing point, allowing for solid-to-liquid transformation without external force or heat source. This invention achieves the transition from storage to use through four steps: melting the curing agent particles, adding surfactants and high-energy solid particles to complete the curing process, and then adding the liquefaction agent to achieve liquefaction. The preparation is simple and low-cost, effectively improving the long-term dispersion stability of the nanofluid fuel. During the storage stage, the dense three-dimensional solid lattice formed after cooling of straight-chain alkanes, along with the surfactants that can efficiently adsorb onto the surface of high-energy metal particles, ensures a uniform dispersion. This chemical anti-settling and physical curing not only achieves the long-term stability of the nanofluid fuel but also protects against leakage risks during transportation, improving the safety of transportation and storage.

[0018] (2) The liquefaction process of the present invention does not require external shear stress or high temperature heat source. By utilizing the dissolution temperature reduction effect of Raoult's law and the principle of lattice collapse, the fuel can spontaneously decondense under normal temperature environment with only simple solvent mixing, and the operation process is convenient.

[0019] (3) The curing agent and liquefying agent used in this invention are themselves high-quality hydrocarbon fuels. They do not require the high-power shear pumps required by traditional gel fuels, which greatly reduces the equipment cost and operating energy consumption of fuel supply. Moreover, the preparation process is simple, which greatly optimizes the economic benefits of fuel. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 Example 2 describes the process for preparing and liquefying solid-state nanofluid fuels; Figure 2A comprehensive comparison of the theoretical solid-liquid phase transition temperatures of the straight-chain alkane (n-octadecane, n-eicosane, n-docosahexadecane, and n-tetracosane)-JP10 system; Figure 3 Image a, from left to right, shows the storage state of the solid nanofluid fuels prepared in Examples 1-1, 1-2, 1-3, and 1-4 after one month; image b, from left to right, shows the morphology of the solid nanofluid fuels prepared in Examples 1-1, 1-2, 1-3, and 1-4 after the addition of a liquefying agent. Figure 4 From left to right, the images show the storage state of the solid nanofluid fuels prepared in Examples 2-1, 2-2, and 2-3 after one month of storage, and the morphological images after the addition of liquefaction agents. Figure 5 From left to right, the images show the storage state of the solid nanofluid fuels prepared in Examples 3-1 and 3-2 after one month of storage, and the morphological images after the addition of liquefaction agents. Detailed Implementation

[0022] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0023] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0024] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0025] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0026] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0027] The room temperature / room temperature in this invention refers to 20-25°C.

[0028] Unless otherwise specified, all materials used in this invention are commercially available products.

[0029] This invention provides a highly stable nanofluid fuel, which includes a solid-state nanofluid fuel and a liquefying agent; the solid-state nanofluid fuel includes high-energy solid particles, a surfactant, and a curing agent.

[0030] In some preferred embodiments of the present invention, the following components are included by mass percentage: high-energy solid particles: 0.1% to 20%, surfactant: 0.1% to 2%, curing agent: 10% to 50%, and the balance being liquefying agent.

[0031] In some preferred embodiments of the present invention, the particle size of the stored solid nanofluid fuel is 0.1 to 3 mm.

[0032] In some preferred embodiments of the present invention, the high-energy solid particles are selected from one or more of boron powder, aluminum powder, or magnesium powder.

[0033] In some preferred embodiments of the present invention, the surfactant includes one or more of Span 85, Span 80 and Tween 85.

[0034] In some preferred embodiments of the present invention, the curing agent is selected from one or more of n-octadecane, n-eicosane, n-docosahexadecane and n-tetracosane.

[0035] In some preferred embodiments of the present invention, the liquefying agent is selected from tetrahydrodicyclopentadiene or tetracycloheptane.

[0036] In some preferred embodiments of the present invention, the method for preparing the solid-state nanofluid fuel includes the following steps: Step 1: Weigh the curing agent using an electronic balance, place the weighed curing agent in a beaker, place it on a magnetic stirrer, and set the heating to complete melting; Step 2: Under constant temperature (80℃), add surfactant to beaker and turn on magnetic stirring to ensure uniform mixing of system; Step 3: Add high-energy solid particles to the beaker and continue stirring at a constant temperature (75°C) until the mixture becomes a uniform suspension with no obvious particle agglomeration or sedimentation. Step 4: Turn off heating and stirring, place the mixture at room temperature to solidify into a block, crush it, and then prepare the storage solid nanofluid fuel.

[0037] This invention also provides a method for using the high-stability nanofluid fuel, wherein a liquefying agent is added to the stored solid nanofluid fuel, and the fuel spontaneously transforms from solid to liquid without heating.

[0038] The core mechanism of the highly stable nanofluid fuel provided by this invention is based on Raoult's law and the van der Hoff ideal solubility equation, wherein the van der Hoff ideal solubility equation is: Where x: mole fraction of curing agent in the system; The latent heat of phase change refers to the enthalpy change required for a curing agent to change from a solid to a liquid state. R: molar gas constant, with a value of 8.314 J / (mol·K); T m : is the melting point (K); T: Target liquefaction temperature (K).

[0039] Raoult's law describes the relationship between vapor pressure and concentration in an ideal solution. This law states that, under ideal solution conditions, the decrease in chemical potential of the system after the introduction of a heterogeneous component into the solvent depends solely on the mole fraction *x* of the solute particles, regardless of the solute's geometry or chemical composition. This inevitable thermodynamic consequence, purely due to the increase in mixing entropy, macroscopically manifests as classical colligative properties such as a decrease in the freezing point of the solution. In a solid-liquid two-phase equilibrium system, by combining this deviation in chemical potential with the van der Hoff equation, the ideal solubility equation currently used to predict the phase transition temperature of ideal solid solutions can be derived.

[0040] Table 1 shows the performance parameters of common straight-chain alkanes. Based on the performance parameters provided in Table 1 and the van der Hoff ideal solubility equation, the changes in the ideal dissolution temperature of straight-chain alkanes with the addition of JP10 are shown in Table 1. Figure 2 As shown.

[0041] Table 1 like Figure 2As shown, ideally, if the system is required to spontaneously achieve solid-liquid phase transition and complete liquefaction at room temperature (20℃), the theoretically required mass fractions of the liquefying agent (JP10) are approximately 34.5% n-octadecane, 64.3% n-eicosane, 81.3 wt% n-docosahexadecane, and 91.4% n-tetracosane. With the increase of the melting point and latent heat of phase transition of alkanes, the proportion of liquefying agent added also increases accordingly to achieve the same dissolution temperature. Therefore, in the provided high-stability nanofluid fuel, when the solidifying agents are n-octadecane, n-eicosane, n-docosahexadecane, and n-tetracosane, and the liquefying agent used is JP10 (carried tetrahydrodicyclopentadiene), the mass percentages of the liquefying agent need to be controlled to be greater than 34.5%, 64.3%, 81.3 wt%, and 91.4%, respectively, to achieve spontaneous solid-liquid phase transition and complete liquefaction at room temperature (20℃).

[0042] Example 1 In this embodiment, amorphous boron particles produced by Shanghai Shuitian Co., Ltd. were selected as high-energy solid particles. The boron particles had a particle size of 80 nm and a purity of 99%. Span 80 was used as the surfactant, JP10 (tetrahydrodicyclopentadiene) was used as the liquefying agent, and n-octadecane was used as the curing agent. The preparation method of storing solid nanofluid fuel in this embodiment includes the following steps: ① Weigh n-octadecane using an electronic balance, place the weighed n-octadecane in a beaker, place it on a magnetic stirrer, and set the heating temperature to 70℃ until it is completely melted; ② Under constant temperature (80℃) conditions, add Span 80 to the beaker, turn on the magnetic stirrer, set the speed to 240 r / min, and the stirring time to 20 min to ensure that the system is mixed evenly; ③ Add boron powder to the beaker and continue stirring for 30 minutes at a constant temperature (75℃) until the mixture is a uniform suspension with no obvious particle agglomeration or sedimentation. ④ Turn off heating and stirring, place the mixture in a room temperature environment to solidify it into a block, and prepare the storage solid nanofluid fuel. By grinding, it is pulverized to obtain the storage solid nanofluid fuel with a particle size of 0.1-3 mm.

[0043] In this embodiment, the steps for using highly stable nanofluid fuel are as follows: JP10 is added to the stored solid nanofluid fuel, and liquefaction is completed. Table 2 shows the percentage of raw material components, particle size of the stored solid nanofluid fuel, and liquefaction time of the four groups of highly stable nanofluid fuels provided in this embodiment and Comparative Example 1. In Comparative Example 1, n-octadecane is not added to prepare the nanofluid fuel.

[0044] Table 2 The solid-state nanofluid fuels prepared in Examples 1-1 to 1-4 were stored for one month. Figure 3 Image a, from left to right, shows the storage state of the solid nanofluid fuels prepared in Examples 1-1, 1-2, 1-3, and 1-4 after one month; image b, from left to right, shows the morphology of the solid nanofluid fuels prepared in Examples 1-1, 1-2, 1-3, and 1-4 after the addition of a liquefying agent. Figure 3 As can be seen from the table: after one month of storage, the curing is uniform and stable. Adding the corresponding JP10 from Table 2 and liquefying it for 10-20 minutes yields the following result: Figure 3 The uniform nanofluid fuel is shown. According to the above theoretical prediction, when the curing agent is n-octadecane, about 34.5% JP10 needs to be added to reach room temperature (20°C). Ignoring the influence of boron and Span 80 on the liquefaction of n-octadecane, 50% JP10 was added to the high-stability nanofluid fuels in Examples 1-1, 1-2, 1-3 and 1-4, which is greater than the theoretical value, and can achieve the liquefaction of stored solid nanofluid fuels.

[0045] Table 3 shows the specific stabilization times of the solid-state nanofluid fuels prepared in Examples 1-1-Examples 1-4 and the nanofluid fuels prepared in Comparative Example 1.

[0046] Table 3 As shown in Table 3, the nanofluid fuel prepared in Comparative Example 1, lacking a curing agent, completely settled within 12 hours, maintaining only good dispersion in the initial mixing stage. With prolonged standing time, the high-density boron powder settled under gravity and van der Waals forces, thus losing its good performance. In contrast, the solid-state nanofluid fuels prepared in Examples 1-1-1-4, after curing and storage, achieved stable storage for more than 30 days, maintaining good performance during use and demonstrating superior long-term storage and stability. This invention, by introducing n-octadecane to solidify and encapsulate the nanofluid fuel during preparation, maintains its optimal dispersion stability over a long period. Liquefaction is achieved simply by adding tetrahydrodicyclopentadiene during use, resulting in a stable nanofluid fuel. Traditional liquid nanofluid fuels, however, have short storage times, settle quickly, and struggle to maintain long-term dispersion stability.

[0047] Example 2 In this embodiment, n-docosahexanes with a longer carbon chain are selected as the curing agent. The other raw materials are the same as in Example 1. Compared with Example 1, n-docosahexanes have a higher melting point and latent heat of phase change. The preparation method of the stored solid nanofluid fuel and the steps of using the high-stability nanofluid fuel are the same as in Example 1. Table 4 shows the percentage of raw material components, particle size of the stored solid nanofluid fuel, and liquefaction time of the three groups of high-stability nanofluid fuels provided in this embodiment. Figure 1 Example 2 describes the process for preparing and liquefying solid nanofluid fuel.

[0048] Table 4 Figure 4 From left to right, the images show the storage state of the solid nanofluid fuels prepared in Examples 2-1, 2-2, and 2-3 after one month of storage, and their morphology after the addition of liquefaction agents. Figure 4 As shown, after one month of storage, the solid nanofluid fuels prepared in Examples 2-1, 2-2, and 2-3 maintained the same morphology as their initial state, demonstrating good solidification and storage performance. Since docosane has a high melting point of 44°C, the present invention placed the aforementioned solid nanofluid fuels in an oven overnight at a temperature of 40°C. The samples did not liquefy due to the increased temperature, exhibiting excellent storage characteristics.

[0049] Compared to n-octadecane, n-docosahexane has a higher melting point and latent heat of phase change; therefore, to achieve liquefaction at room temperature, a higher mass ratio of JP10 needs to be added, such as... Figure 4 As shown, liquefaction can be fully achieved after 10-20 minutes after the addition of JP10. Based on the above theoretical prediction, approximately 81.3% JP10 is required to reach room temperature (20°C). Ignoring the effects of boron and Span 80 on the liquefaction of n-dodecane, the high-stability nanofluid fuels in Examples 2-1, 2-2, and 2-3 contained 87.3%, 85%, and 75% JP10, respectively, which are close to the theoretical calculations, confirming the accuracy of the theoretical calculations.

[0050] Example 3 This embodiment mainly explores the effect of the particle size of stored solid nanofluid fuel on the fuel liquefaction rate. The experiment uses a uniform base liquid formula. The specific component content and liquefaction time are shown in Table 5. The preparation method is the same as in Example 2. Table 5 shows the percentage of raw material components, particle size of stored solid nanofluid fuel, and liquefaction time of the two groups of high-stability nanofluid fuels provided in this embodiment.

[0051] Table 5 Figure 5From left to right, the images show the storage state of the solid nanofluid fuels prepared in Examples 3-1 and 3-2 after one month of storage, and their morphology after the addition of liquefaction agents. Figure 5 As shown, after one month of storage, the particles are generally evenly dispersed. Figure 5 The left side shows Example 3-1, where the overall solidified storage fragments have a larger particle size; while the right side shows Example 3-2, which is a solidified fuel with smaller particles after pulverization. According to the proportions shown in Table 5, with the same mass of JP10 added, after 20 minutes, the solidified nanofluid fuel prepared in Example 3-2 achieved uniform liquefaction and distribution, presenting a uniform suspension, while Example 3-1 required 2 hours to fully liquefy. Because the smaller particles have a higher specific surface area, the effective contact area with the liquefying agent is larger, increasing the liquefaction rate and shortening the liquefaction time. Experiments show that the pulverized solidified nanofluid fuel can also maintain a uniform dispersion effect, and the liquefaction rate during the liquefaction stage is high, accelerating from 2 hours to 20 minutes, significantly reducing the waiting time for liquefaction.

[0052] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A highly stable nanofluid fuel, characterized in that, The highly stable nanofluid fuel includes a solid nanofluid fuel storage unit and a liquefying agent; the solid nanofluid fuel storage unit includes high-energy solid particles, a surfactant, and a curing agent.

2. The highly stable nanofluid fuel according to claim 1, characterized in that, The product comprises the following components by mass percentage: high-energy solid particles: 0.1%–20%, surfactant: 0.1%–2%, curing agent: 10%–50%, and the balance being liquefying agent.

3. The highly stable nanofluid fuel according to claim 1, characterized in that, The particle size of the stored solid nanofluid fuel is 0.1–3 mm.

4. The highly stable nanofluid fuel according to claim 1, characterized in that, The high-energy solid particles are selected from one or more of boron powder, aluminum powder, or magnesium powder.

5. The highly stable nanofluid fuel according to claim 1, characterized in that, The surfactant includes one or more of Span 85, Span 80, and Tween 85.

6. The highly stable nanofluid fuel according to claim 1, characterized in that, The curing agent is selected from one or more of n-octadecane, n-eicosane, n-docosahexadecane, and n-tetracosane.

7. The highly stable nanofluid fuel according to claim 1, characterized in that, The liquefying agent is selected from tetrahydrodicyclopentadiene or tetracycloheptane.

8. The highly stable nanofluid fuel according to claim 1, characterized in that, The preparation method of the solid-state nanofluid fuel includes the following steps: adding a surfactant to a molten curing agent, mixing it for the first time at a constant temperature, then adding high-energy solid particles, mixing it for the second time at a constant temperature, stopping heating, solidifying it into a block at room temperature, and pulverizing it to obtain the solid-state nanofluid fuel.

9. The highly stable nanofluid fuel according to claim 8, characterized in that, The initial mixing temperature under constant temperature is 80°C, and the secondary mixing temperature under constant temperature is 75°C.

10. A method of using the highly stable nanofluid fuel according to any one of claims 1 to 9, characterized in that, When in use, the liquefying agent is added to the stored solid nanofluid fuel, and it can spontaneously transform from solid to liquid nanofluid fuel without heating.

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