Aviation kerosene biological alternative fuel based on multi-objective optimization

Abstract

The invention relates to the technical field of biofuels, and discloses an aviation kerosene biological alternative fuel based on multi-objective optimization, which is characterized in that a comprehensive selection index system comprising density, kinematic viscosity, thermodynamic characteristics (lower calorific value and hydrogen-carbon ratio) and molecular weight is established based on a multi-objective optimization model constructed by a genetic algorithm; the invention discloses a biological fuel formula for replacing RP-3 aviation kerosene by optimizing the design of biological alternative fuel components, the biological alternative fuel is prepared from the following components in parts by volume: 70-80 parts of second-generation biodiesel, 10-15 parts of tetrahydrofuran and 7-15 parts of isopropanol, the components are easy to obtain, the production process is simple, and the biological alternative fuel is suitable for large-scale production. The second-generation biodiesel, tetrahydrofuran and isopropanol are used as raw materials, the obtained biofuel has low kinematic viscosity, the low calorific value reaches 43 MJ / kg or above, the physicochemical property of the biofuel is similar to that of RP-3 aviation kerosene, and the biofuel has good substitutability and wide popularization value.

Description

Technical Field

[0001] This invention relates to the field of biofuel technology, and more specifically to a biofuel alternative to aviation kerosene based on multi-objective optimization. Background Technology

[0002] With the rapid development of the global economy, the aviation industry is booming, but it also faces both opportunities and severe challenges. A particularly prominent issue is the environmental threat posed by the large-scale consumption of aviation kerosene (e.g., CO2, CO, NO). x (etc.). In order to mitigate the environmental impact of aviation fuel, the International Air Transport Association (IATA) has also set targets for controlling carbon emissions: to improve fuel efficiency by 1.5% annually from 2009 to 2020; to achieve zero carbon emissions growth by 2020; and to reduce carbon emissions by 50% by 2050 compared to 2005.

[0003] With the rapid development of the aviation industry, RP-3 aviation fuel is the mainstay aviation kerosene in my country's military and civil aviation sectors. It boasts advantages such as a narrow distillation range (150℃-280℃) and excellent low-temperature fluidity, meeting the requirements for use in high-altitude, low-temperature environments. Furthermore, RP-3 has a high calorific value and stable combustion efficiency, providing continuous and sufficient power to aero engines. Its high cleanliness and low sulfur content reduce engine carbon deposits and corrosion, extending equipment lifespan. However, RP-3's cetane number is between gasoline and diesel, significantly lower than diesel, resulting in a longer ignition delay and insufficient ignition reliability. In compression-ignition engines, excessive premixed gas generation is likely, leading to higher hydrocarbon (HC) emissions than diesel. Additionally, due to its weaker ignition performance, the increase in unburned hydrocarbon (HC) intermediates during combustion further contributes to higher HC emissions than diesel, especially under low-load conditions. Therefore, achieving IATA's DE targets is extremely difficult given the widespread use of RP-3. Thus, in-depth exploration of biofuels as a supplementary fuel to aviation kerosene is particularly important. This research field not only aims to alleviate the tight supply of aviation kerosene, but also strives to reduce the aviation industry's contribution to greenhouse gases, which is of strategic significance for promoting the green transformation of the aviation industry and the long-term sustainable development of my country's ecological environment.

[0004] Therefore, our team aims to innovatively design a biofuel to replace RP-3 aviation kerosene in order to solve current energy and environmental problems. Summary of the Invention

[0005] The present invention aims to provide a bio-alternative aviation kerosene fuel based on multi-objective optimization, so as to replace RP-3 aviation fuel and solve current energy and environmental problems.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a bio-alternative fuel for aviation kerosene based on multi-objective optimization, which is composed of the following raw materials in parts by weight: 70-80 parts of second-generation biodiesel, 10-15 parts of tetrahydrofuran, and 7-15 parts of isopropanol. Preferably, as an improvement, the bio-alternative fuel is a liquid fuel with a low calorific value ≥43MJ / kg.

[0007] Preferably, as an improvement, the biofuel has a density of 0.772-0.795 g / mL; a hydrogen / carbon ratio of 2.13-2.16; and a kinematic viscosity of 1.590-1.78 mm. 2 / s.

[0008] Preferably, as an improvement, a method for preparing aviation kerosene bio-alternative fuel based on multi-objective optimization includes the following steps: S1. Establish a candidate component library for biofuel alternatives; S2. Collect the physicochemical property data of all components in the candidate component library; S3. Based on the physicochemical properties data, the components in the candidate component library are screened to obtain a preliminary component dataset; S4. Construct a multi-objective optimization model; S5. Based on the genetic algorithm, the component allocation ratio in the initial component dataset is optimized through multiple generations of iteration, and the optimal component formula is output to prepare bio-alternative fuels. S6, Performance Verification.

[0009] Preferably, as an improvement, in step S1, the candidate component library includes biodiesel, ethers, alcohols, and furan biofuels.

[0010] Preferably, as an improvement, in step S2, the physicochemical property data includes component density, kinematic viscosity, thermodynamic properties and molecular weight data, and the thermodynamic properties include lower heating value and hydrogen-to-carbon ratio.

[0011] Preferably, as an improvement, in step S4, the calculation formulas for the various selection indicators of bio-alternative fuels are as follows: (1) to (5): Formula for calculating the average molecular weight of biomass fuel:

[0012] Formula for calculating the hydrogen-to-carbon ratio of biomass fuels:

[0013] Formula for calculating the lower calorific value of biomass fuel:

[0014] Formula for calculating the density of biomass fuel:

[0015] Formula for calculating the viscosity of biomass fuel:

[0016] In the formula, v i x is the volume fraction. i y is the mole fraction. i ρ is the mass fraction, η is the density, T is the viscosity, and T is the temperature.

[0017] Preferably, as an improvement, the optimized function is as shown in equation (6).

[0018] In the formula, N target To determine the number of selection indicators, E i,sur E is the selection index value for biomass fuel. i,RP-3 The selection index value for RP-3 aviation kerosene is denoted as ; the smaller the fitness function value of the best individual, the higher its fitness is ; when the iteration reaches a certain number of times, the average fitness of the population reaches the threshold, the calculation is terminated and the final result is output, obtaining the biomass fuel component ratio.

[0019] Preferably, as an improvement, the application of aviation kerosene bio-alternative fuel based on multi-objective optimization in aviation fuel.

[0020] Preferably, as an improvement, biofuel alternatives are used alone.

[0021] The principle and advantages of this solution are as follows: In practical applications, current direct-process bio-jet fuels have low aromatic hydrocarbon content, low density, high viscosity, and are prone to leakage. They cannot meet immediate use requirements when used alone and must be blended with petroleum-based jet fuel before being put into flight. Furthermore, due to the complex composition of aviation kerosene, alternative fuels are often selected based on their higher content of components or alkanes with similar carbon and hydrogen atom numbers, which still cannot avoid harm to energy and the environment. This technical solution innovatively develops a bio-alternative fuel (bio-liquid fuel) that can be used alone. Considering the stringent performance requirements of aviation kerosene in its application scenarios—meeting combustion efficiency under high temperature and pressure conditions in engines, ensuring stable injection atomization, and controlling pollutant emissions—this solution, for the first time, constructs a comprehensive selection system including five key physicochemical parameters, each corresponding to the core functional requirements of aviation kerosene. Density (20℃): Directly affects the amount of fuel stored in the fuel tank and the efficiency of pipeline transportation. If the density deviation is too large, it will lead to inaccurate metering of the engine fuel supply system. The solution controls it at 0.795g / ml (0.7846g / ml for RP-3), with a deviation of only 1.3%, ensuring compatibility with the existing fuel supply system. Kinematic viscosity: A key indicator determining fuel atomization. Too high a viscosity results in insufficient fuel breakup during injection, forming large droplets, leading to incomplete combustion and increased carbon buildup; too low a viscosity may cause leaks in pipeline seals. The proposed solution reduces the viscosity to 1.590 mmHg by adding tetrahydrofuran and isopropanol. 2 / s (RP-3 is 1.78mm) 2 / s), which solves the problem of high viscosity of traditional biodiesel and avoids the risk of leakage caused by excessive dilution; Low calorific value: Aero engines have extremely high requirements for fuel energy density, and the low calorific value directly determines the aircraft's range. The proposed solution uses second-generation biodiesel as the main component (accounting for 78.15%), which itself has a high energy density, ultimately achieving a fuel low calorific value of 43.28 MJ / kg, only 0.32% lower than RP-3 (43.42 MJ / kg), with almost no impact on range. Hydrogen-to-carbon ratio: directly related to carbon emissions during fuel combustion—the higher the hydrogen-to-carbon ratio, the less CO2 is produced per unit of energy during combustion. The proposed solution controls the hydrogen-to-carbon ratio at 2.16 (2.08 for RP-3), further reducing carbon emissions while ensuring energy density, aligning with the aviation industry's "carbon reduction" goals. Molecular weight: By blending multiple components (second-generation biodiesel + tetrahydrofuran + isopropanol), the average molecular weight of the fuel is adjusted to match the intermolecular forces and evaporation rate of RP-3, avoiding excessively fast or slow combustion speeds due to molecular weight differences, and ensuring stable engine power.

[0022] Furthermore, traditional biofuel formulation design often employs a "trial and error" approach, which involves manually adjusting component ratios and verifying performance one by one. This method is prone to falling into the dilemma of single-parameter optimization and multi-parameter conflicts (for example, reducing viscosity may lead to a significant decrease in calorific value, while increasing the hydrogen-to-carbon ratio may cause viscosity to exceed limits). In contrast, the genetic algorithm used in this solution essentially simulates the "selection-crossover-mutation" process of biological evolution, achieving synergistic optimization of multiple parameters. (1) Initial population construction: Different ratios of candidate component libraries (biodiesel, ethers, alcohols, furans) are used as initial individuals, and each individual corresponds to a set of physicochemical parameters (density, viscosity, low calorific value, etc.); (2) Fitness function calculation: The square root of the sum of squares of the deviations of each fuel parameter from RP-3 is used as the fitness index (Formula 6). The smaller the deviation, the higher the fitness. This means that the goal of the algorithm is to make the overall performance of the fuel as close as possible to RP-3, rather than the single parameter optimization; (3) Multi-generation iterative optimization: Through "selection" (retaining individuals with high fitness), "crossover" (combining the ratios of two individuals with high fitness to generate new individuals), and "mutation" (randomly adjusting the ratios of some individuals to avoid getting trapped in local optima), after 182 generations of iteration, the average fitness of the population reaches the preset threshold, and finally the optimal ratio (78.15% second-generation biodiesel + 13.61% tetrahydrofuran + 8.24% isopropanol) is output.

[0023] This technical solution, based on a genetic algorithm, obtained the optimal formula and then investigated its actual atomization and combustion characteristics. A key aspect of this solution is the use of high-precision experimental platforms such as constant-volume incendiary bombs and shock tubes to verify the relevant atomization and basic combustion characteristics. The challenges overcome in this process include: Atomization characteristics verification: It is necessary to prove that the high viscosity disadvantage caused by biodiesel can be effectively offset by tetrahydrofuran and isopropanol, so that the atomization effect of the mixed fuel is similar to that of RP-3 aviation kerosene, which can meet the stringent requirements of aircraft engines.

[0024] Basic combustion characteristics verification: It is necessary to verify that the bio-based formulation is sufficiently close to RP-3 kerosene in key combustion parameters such as ignition delay time and laminar flame velocity to ensure that it will not cause knocking, flameout, or efficiency reduction in existing engines. This realizes the verification from "theoretically ideal formulation" to "feasible fuel in the laboratory".

[0025] The core advantage of this technical solution lies in its innovative application of genetic algorithms, typically used in computer science and engineering optimization, to fuel development. It creatively integrates genetic algorithms, commonly applied in computer science and engineering optimization, into fuel development. This allows it to find the global optimum among multiple conflicting objectives, such as low viscosity (often used as a post-hoc verification indicator, but innovatively treated as a "satisfaction indicator"), low calorific value with high density matching, and high hydrogen-to-carbon ratio (a fundamental chemical structure parameter often overlooked in complex combustion models and not considered an independent prerequisite for optimization; this solution explicitly lists the hydrogen-to-carbon ratio as one of the comprehensive selection indicators, leading the algorithm to prioritize chemically cleaner and more efficient molecular combinations, resulting in fuels that not only match RP-3 in macroscopic performance but also tend to be superior at the fundamental level of molecular combustion). This approach avoids sacrificing one parameter to satisfy another, a feat impossible with traditional trial-and-error methods.

[0026] In the early stages of technology development, the inventors attempted to design the formula following traditional approaches, prioritizing "maximizing calorific value," resulting in a high proportion of biodiesel. While this formula achieved a calorific value close to or even reaching that of RP-3, its kinematic viscosity was excessively high. In atomization experiments with constant-volume combustion bombs, the small fuel spray cone angle led to poor evaporation and mixing performance, incomplete combustion, and a significantly lower atomization effect compared to RP-3. At high biodiesel content, the formula may crystallize or experience a sharp decrease in fluidity at low temperatures, failing to meet the wide-temperature-range requirements for aviation fuel.

[0027] In addition, the inventors' team also attempted an optimized formulation consisting of second-generation diesel + methanol + n-propanol / n-butanol. This formulation performed well in the multi-objective optimization model, with good calculated values ​​for various macroscopic indicators (density, calorific value). However, in reality, methanol and biodiesel have poor compatibility, especially at low temperatures or in the presence of moisture, leading to phase separation and making the formulation unstable and unsuitable for practical application. Furthermore, methanol has a swelling effect on some elastic sealing materials, and its high latent heat of vaporization may negatively impact engine cold starts. This failure highlights that the molecular compatibility and chemical stability of components are crucial but easily overlooked "hidden" criteria. This forced the team to consider this constraint in the candidate biofuel components, ultimately selecting components such as tetrahydrofuran and isopropanol, which have excellent miscibility with biodiesel and better material compatibility, ensuring the physical stability and engineering practicality of the formulation.

[0028] In summary, the beneficial effects of this technical solution are as follows: 1. This technical solution is not limited to a single type of component, but combines "high energy density second-generation biodiesel" (main component), "low viscosity tetrahydrofuran" (to regulate atomization), and "low cost isopropanol" (to assist in regulating molecular weight) to achieve complementary performance.

[0029] 2. This technical solution uses a genetic algorithm to control the deviation of various key parameters from RP-3 to within 5% (some parameters, such as low calorific value, have a deviation of only 0.32%). The developed bio-alternative fuel can be used alone without blending, thus replacing aviation kerosene.

[0030] 3. In this technical solution, the developed bio-alternative fuel reduces the kinematic viscosity of the fuel while ensuring the calorific value. At the same time, the parameters such as the fuel density, carbon-hydrogen ratio, and surface tension are similar to those of aviation kerosene RP-3, demonstrating its feasibility as a potential alternative fuel. Moreover, the low calorific value of this bio-alternative fuel reaches more than 43 MJ / kg. Attached Figure Description

[0031] Figure 1 This represents the optimal function value for the best individual in this embodiment of the invention.

[0032] Figure 2 This describes the fuel spray development process under operating conditions of 2.1MPa-80MPa-423K in an embodiment of the present invention.

[0033] Figure 3 This refers to the ignition delay time of RP-3 aviation kerosene and bio-alternative fuel in this embodiment of the invention.

[0034] Figure 4 This describes the flame development process of fuel under operating conditions of 1-0.2MPa-400K in an embodiment of the present invention. Detailed Implementation

[0035] The following detailed description provides further details on specific embodiments, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the technical means used in the following embodiments are conventional means well known to those skilled in the art; the experimental methods used are all conventional methods; and the materials and reagents used are all commercially available.

[0036] Overview of the plan: A biofuel alternative to aviation kerosene based on multi-objective optimization, the fuel being a liquid fuel comprising, by mass percentage, 78.15% second-generation biodiesel, 13.61% tetrahydrofuran, and 8.24% isopropanol.

[0037] A biofuel alternative to aviation kerosene based on multi-objective optimization, the fuel formulation optimization design includes the following steps: S1. Establish a candidate component library for biofuel alternatives, which includes common biofuels such as biodiesel, ethers, alcohols, and furans; S2. Collect the physicochemical property data of all components in the candidate component library, including component density, kinematic viscosity, thermodynamic properties (lower heating value, hydrogen-to-carbon ratio) and molecular weight data. S3. Based on the physicochemical properties data, the components in the candidate component library are screened to obtain a preliminary component dataset; S4. Construct a multi-objective optimization model, where the calculation formulas for various selection indicators of biofuel alternatives are as follows: Average molecular weight of biomass fuel:

[0038] Hydrogen-to-carbon ratio of biomass fuels:

[0039] Low calorific value of biomass fuel:

[0040] Density of biomass fuel:

[0041] Viscosity of biomass fuel:

[0042] In the formula, v i x is the volume fraction. i y is the mole fraction. i ρ is the mass fraction, η is the density, T is the viscosity, and T is the temperature.

[0043] The optimization function is shown in equation (6).

[0044] In the formula, N target To determine the number of selection indicators, E i,sur E represents a certain selection index value for biomass fuel. i,RP-3 This refers to a selection index value for RP-3 aviation kerosene.

[0045] The smaller the fitness function value of the optimal individual, the higher its fitness. When the iteration reaches a certain number of times, the average fitness of the population reaches a threshold, the calculation terminates, and the final result is output, yielding the biomass fuel composition ratio.

[0046] S5. Optimize the group allocation ratios in the initially selected component dataset through multiple generations using a genetic algorithm; for example... Figure 1As shown, during the iterative process of the genetic algorithm, after 182 iterations, the optimization function value of the best-performing individual in each generation of the population exhibits a continuous downward trend. This dynamic change process essentially reflects an efficient approximation strategy for the minimum value of the problem function. Specifically, as the iteration deepens, the continuous decrease in the optimization function value is directly related to the improvement of individual fitness; that is, a lower function value means a higher fitness level. When the algorithm iterates to a certain number of times, the average fitness of the entire population crosses the preset threshold, marking the convergence of the optimization process. At this point, the algorithm terminates and outputs the final optimization result, which corresponds to an optimization function value of 1.71 × 10⁻⁶. -3 This demonstrates the effectiveness of the algorithm in terms of solution efficiency and accuracy.

[0047] S6. Prepare bio-alternative fuels based on the optimal component formula output by the genetic algorithm; S7. The final bio-alternative fuel formula was obtained by verifying it through atomization and basic combustion characteristic experiments.

[0048] Example 1 To prepare biofuel alternatives, mix the following components and proportions (stir until homogeneous at room temperature) to obtain the biofuel alternatives: Second-generation biodiesel 78.15% Tetrahydrofuran 13.61% Isopropanol 8.24%.

[0049] Experimental Example 1: Analysis of Physicochemical Properties The physicochemical properties of the bio-alternative fuel prepared in Example 1 and RP-3 aviation kerosene were analyzed, and the results are shown in Table 1: Table 1. Partial physicochemical properties of Example 1 and RP-3 aviation kerosene

[0050] Comparative Example 1 The difference between this comparative example and Example 1 is that in this example, the bio-alternative fuel composition is 67.97% second-generation biodiesel + 23.03% methyl tert-butyl ether + 9% n-butanol. Testing showed its density to be 0.797 g / ml, lower heating value 42.62 MJ / kg, hydrogen-to-carbon ratio 2.07, surface tension 22.454, and kinematic viscosity 1.438 mm. 2 / s, which is not ideal compared to Example 1.

[0051] Comparative Example 2 In this comparative example, the proportion of second-generation biodiesel was increased to 85% or even 90% in order to better utilize its renewable properties. However, although such formulations perform reasonably well in terms of calorific value, their kinematic viscosity is significantly excessive, leading to a sharp deterioration in atomization performance during constant-volume combustion bomb testing, which fails to meet the stringent requirements of aero-engines for fuel injection and combustion efficiency.

[0052] Comparative Example 3 In this comparative example, other common oxygen-containing components, such as methanol or ethanol, were used to replace tetrahydrofuran and isopropanol. However, these lower alcohols have poor compatibility with second-generation biodiesel, are prone to phase separation under wide temperature range conditions, and have insufficient system stability. We also considered using components such as n-butyl ether to replace oxygen-containing components, but these were abandoned due to economic reasons.

[0053] Comparative Example 4 In this comparative example, in pursuit of formulation simplicity, a two-component system consisting only of biodiesel and one main solvent was attempted. However, experiments demonstrated that no single solvent can simultaneously and perfectly control the viscosity, polarity, hydrogen-to-carbon ratio, and calorific value of the fuel. For example, while using only tetrahydrofuran can effectively reduce viscosity, it may cause the overall hydrogen-to-carbon ratio and calorific value to deviate from the target; using only isopropanol may introduce new problems related to miscibility and stability while improving viscosity.

[0054] Experiment Example 2: Atomization Characteristics Test of Bioalternative Fuel Formulation The bio-alternative fuel prepared in Example 1 was subjected to atomization characteristic tests. Atomization, as the initial stage of the combustion process, has a significant impact on engine combustion efficiency. Therefore, after obtaining a biomass fuel formulation with properties similar to RP-3 aviation kerosene, the spray characteristics of RP-3 aviation kerosene and the bio-alternative fuel were studied in a high-temperature, high-pressure, constant-volume combustion bomb. Taking an injection pressure of 80 MPa, an ambient back pressure of 2.1 MPa, and an ambient temperature of 423 K as an example, the atomization characteristics of the fuel were tested. The spray of both fuels exhibited a typical three-stage development characteristic of "jet-split-atomization": in the initial stage, the liquid core jet is dominant, and the boundary is formed by the shearing of the airflow, resulting in slight disturbances; then the disturbances amplify, causing the liquid core to break into liquid filaments and large droplets, forming a continuous spray cone; finally, the liquid filaments further break into small droplets, and the spray field gradually stabilizes. This development law is highly consistent with the spray evolution process of RP-3 aviation kerosene, verifying the feasibility of this bio-alternative fuel in terms of spray dynamics. Its spray development process is as follows: Figure 2 .

[0055] Experiment Example 3: Basic Combustion Characteristics Test of Bioalternative Fuel Formulation The combustion characteristics of the bio-alternative fuel prepared in Example 1 were tested, and the test indicators included: (1) Ignition delay time: Ignition delay is of great significance for improving combustion efficiency, improving fuel thermal efficiency and reducing pollutant emissions.

[0056] Test method: The ignition delay time of RP-3 aviation kerosene and bio-alternative fuel was studied using a shock tube test platform with an equivalence ratio of 1 and initial pressures set at 0.2 MPa and 0.9 MPa, respectively.

[0057] Test results: such as Figure 3 As shown, the logarithm of the ignition delay time for both fuels is linearly related to the reciprocal of the ignition temperature, and gradually shortens as the ignition temperature increases. With increasing pressure, the reaction rate increases, and the ignition delay time of the fuel decreases. At an equivalence ratio of 1 and initial pressures of 2 atm and 9 atm, the ignition delay time of the biofuel matches well with that of RP-3 aviation kerosene.

[0058] (2) Laminar combustion rate: The laminar combustion rate reflects the most important and fundamental physicochemical properties of the gas mixture. It is a comprehensive reflection of the overall diffusivity, heat release capacity and combustion reaction rate of the combustible gas mixture.

[0059] Test method: The laminar combustion rate of biomass fuel and actual RP-3 aviation kerosene was compared using a constant volume incendiary bomb test platform.

[0060] Test results are as follows Figure 4 As shown, taking an equivalence ratio of 1, an ambient back pressure of 0.2 MPa, and an ambient temperature of 400 K as an example, the flame development processes of biofuel and RP-3 aviation kerosene are highly similar under the same operating conditions: in the early stages of flame core development, influenced by the ignition electrode, the flame core develops slowly along the electrode direction; a small portion of the heat from fuel combustion is conducted to the ignition electrode, heating it and ultimately affecting the direction of flame core propagation. A MATLAB program was used to process the image, obtain the flame radius, and calculate the laminar combustion rate. The calculated laminar combustion rates for biofuel and RP-3 aviation kerosene were 47.6 cm / s and 47.5 cm / s, respectively, verifying the accuracy of biofuel in predicting the combustion characteristics of RP-3 aviation kerosene.

[0061] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A biofuel alternative to aviation kerosene based on multi-objective optimization, characterized in that, It is composed of the following raw materials in parts by weight: 70-80 parts second-generation biodiesel, 10-15 parts tetrahydrofuran, and 7-15 parts isopropanol.

2. The aviation kerosene bio-alternative fuel based on multi-objective optimization according to claim 1, characterized in that: The biofuel is a liquid fuel with a lower calorific value of ≥43MJ / kg. The mass fraction of each raw material in the biofuel is 78.15 parts second-generation biodiesel, 13.61 parts tetrahydrofuran, and 8.24 parts isopropanol.

3. The aviation kerosene bio-alternative fuel based on multi-objective optimization according to claim 1, characterized in that: The density of biofuel alternatives is 0.772-0.795 g / mL; the hydrogen / carbon ratio is 2.13-2.16; and the kinematic viscosity is 1.590-1.78 mm. 2 / s.

4. A method for preparing aviation kerosene bio-alternative fuel based on multi-objective optimization according to any one of claims 1 to 3, characterized in that, Includes the following steps: S1. Establish a candidate component library for biofuel alternatives; S2. Collect the physicochemical property data of all components in the candidate component library; S3. Based on the physicochemical properties data, the components in the candidate component library are screened to obtain a preliminary component dataset; S4. Construct a multi-objective optimization model; S5. Based on the genetic algorithm, the component allocation ratio in the initial component dataset is optimized through multiple generations of iteration, and the optimal component formula is output to prepare bio-alternative fuels. S6, Performance Verification.

5. The method for preparing aviation kerosene bio-alternative fuel based on multi-objective optimization according to claim 4, characterized in that: In step S1, the candidate component library includes biodiesel, ethers, alcohols, and furan biofuels.

6. The method for preparing aviation kerosene bio-alternative fuel based on multi-objective optimization according to claim 5, characterized in that: In step S2, the physicochemical property data include component density, kinematic viscosity, thermodynamic properties and molecular weight data. The thermodynamic properties include lower heating value and hydrogen-to-carbon ratio.

7. The method for preparing aviation kerosene bio-alternative fuel based on multi-objective optimization according to claim 6, characterized in that: In step S4, the calculation formulas for the various selection indicators of bio-alternative fuels are as follows: (1) to (5): Formula for calculating the average molecular weight of biomass fuel: Formula for calculating the hydrogen-to-carbon ratio of biomass fuels: Formula for calculating the lower calorific value of biomass fuel: Formula for calculating the density of biomass fuel: Formula for calculating the viscosity of biomass fuel: In the formula, v i x is the volume fraction. i y is the mole fraction. i ρ is the mass fraction, η is the density, T is the viscosity, and T is the temperature.

8. The method for preparing aviation kerosene bio-alternative fuel based on multi-objective optimization according to claim 7, characterized in that: The optimization function is shown in equation (6). In the formula, N target To determine the number of selection indicators, E i,sur E is the selection index value for biomass fuel. i,RP-3 The selection index value for RP-3 aviation kerosene is: the smaller the fitness function value of the best individual, the higher its fitness is; when the iteration reaches a certain number of times, the average fitness of the population reaches the threshold, the calculation is terminated and the final result is output, and the biomass fuel component ratio is obtained.

9. The application of a multi-objective optimization-based biofuel for aviation kerosene in aviation fuel, as described in any one of claims 1 to 3.

10. The application of a multi-objective optimization-based biofuel for aviation kerosene in aviation fuel according to claim 9, characterized in that: The biofuel can be used alone.

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