Green and clean ADN-based electric control gel propellant and preparation method thereof

Abstract

The invention discloses a green and clean ADN-based electric control gel propellant and a preparation method thereof, and belongs to the field of special liquid propellants. The electrically controlled gel propellant comprises: 65%-75% of an ADN solution; 10%-15% of ammonium nitrate; 10%-20% of fuel; 5%-10% of a gelling agent; and 0.2%-2% of a functional additive. According to the ADN-based electrogel propellant, ammonium dinitramide serves as a main oxidizing agent, and the propellant has the electrical excitation trigger ignition characteristic and has the advantages of being continuously adjustable in thrust and clean in combustion product. Through optimization of formula design and process innovation, the problems of high pollution, high toxicity, limited ignition technology, high maintenance difficulty and the like of a traditional propellant are solved, and the propellant can be applied to the technical field of space micro-propulsion of a spaceflight micro-propulsion system and the like.

Description

Technical Field

[0001] This invention belongs to the field of special liquid propellants, specifically relating to a green and clean ADN-based electro-controlled gel propellant and its preparation method. Background Technology

[0002] With the development of aerospace technology, space propulsion technology is continuously evolving towards precision and environmental protection. Existing space propulsion systems mainly fall into four categories: chemical propulsion, electric propulsion, nuclear propulsion, and emerging technologies. Chemical propulsion is further divided into solid propulsion, liquid propulsion, and hybrid solid-liquid propulsion. Solid propulsion is difficult to adjust thrust, liquid propulsion has a complex structure, and hybrid solid-liquid propulsion has a low fuel regression rate. Electric propulsion (such as ion and Hall thrusters) has high specific impulse and is suitable for deep space exploration and long-term satellite orbit maintenance, but it has low thrust, complex structure, and high design difficulty. Nuclear propulsion is still in the research and development stage. Emerging technologies (such as light sails and antimatter propulsion) are still in the experimental or conceptual stage. Cold gas propulsion is used for microsatellite attitude fine-tuning, but its endurance is limited, constrained by high-pressure containers, and its continuous operating time is short, making it difficult to meet long-term propulsion requirements.

[0003] In recent years, to address the growing demand in the space propulsion field, electrically controlled gel propellants have provided an effective technological approach. Electrically controlled gel propellants are a novel type of propellant that combines the characteristics of gel propellants with electro-regulation capabilities. By uniformly mixing a solid dispersion in a liquid dispersion, adding a gelling agent and other additives, a three-dimensional propellant with a fixed gel morphology is formed. It combines the high energy density and high specific impulse of traditional solid propellants with the controllable combustion characteristics of liquid propellants. Using ADN solution as the energy base liquid, its gel propellant can ignite sensitively to electrical stimulation, enabling instantaneous start-stop and flow regulation of propellant combustion. Furthermore, complete combustion produces water and nitrogen, resulting in clean combustion products, effectively overcoming the disadvantages of hydrazine-based liquid propellants such as flammability, explosiveness, and high toxicity.

[0004] Designing an ADN-based gel propellant with electrically triggered ignition characteristics, adjustable thrust, and clean combustion products is of significant research importance and practical engineering application value. Summary of the Invention

[0005] The purpose of this invention is to provide a green and clean ADN-based electro-controlled gel propellant and its preparation method, which can overcome the limitations of existing ADN-based propellant catalytic ignition and the defects of unstable gel performance and difficult ignition in gel propulsion technology.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] A green and clean ADN-based electro-gel propellant, the components of which include ADN solution, ammonium nitrate, fuel, gelling agent, and functional additives;

[0008] Based on the total mass of the gel propellant being 100%, the mass percentage content of each component is as follows:

[0009] ADN solution: 65%~75%;

[0010] Ammonium nitrate: 10%–15%;

[0011] Fuel: 10%–20%;

[0012] Gelling agent: 5%–10%;

[0013] Functional additives: 0.2%–2%.

[0014] Furthermore, ammonium dinitramide (ADN) solution is the main oxidant.

[0015] Furthermore, the ADN solution has a mass fraction concentration of 75%.

[0016] Furthermore, the fuel is preferably one or a mixture of methanol and glycerol, both of which are analytical grade.

[0017] Furthermore, the gelling agent is preferably one or a mixture of sodium alginate and sodium carboxymethyl starch.

[0018] Furthermore, the functional additives are thickeners and surfactants.

[0019] Furthermore, the thickener is preferably one or more of methylcellulose, ethylcellulose, and sodium carboxymethylcellulose.

[0020] Furthermore, pectin is the preferred surfactant.

[0021] A method for preparing a green and clean ADN-based electro-controlled gel propellant, the method comprising the following steps:

[0022] 1) Mix the weighed ADN solution and fuel, and use a vacuum stirrer to stir under vacuum at room temperature and a speed of 1000 r / min for 2 min to obtain mixed propellant solution A;

[0023] 2) Add the auxiliary oxidant to the propellant mixture solution A obtained in step 1), and stir it for 5 minutes at a constant temperature of 40℃ and a speed of 1500r / min using a vacuum stirrer until the auxiliary oxidant is completely dissolved to obtain the mixed propellant solution B.

[0024] 3) Add the gelling agent to the propellant mixture solution B obtained in step 2), sonicate for 5 min, and stir with a vacuum mixer at a constant temperature of 40℃ and a speed of 2000 r / min for 20 min until the gelling agent is fully expanded and dissolved and there are no obvious large particles in the solution, to obtain a flowable viscous liquid C.

[0025] 4) Add thickener and surfactant to the flowable viscous liquid C obtained in step 3), and stir with a vacuum mixer at a constant temperature of 40℃ and a speed of 2000r / min for 20min until the gel propellant is uniform and free of bubbles and the system loses its fluidity.

[0026] 5) Cool the gel propellant obtained in step 4) to room temperature to obtain a uniform and stable gel propellant.

[0027] Compared with the prior art, the present invention has the following unique advantages:

[0028] 1) The main oxidant used in this invention is ADN, which has an oxygen balance of +25.79%, higher than the oxygen balance of hydroxylamine nitrate HAN (+21.43%). During combustion, it can provide more active oxygen to the fuel to improve combustion efficiency.

[0029] 2) This invention uses electric ignition technology, which has advantages over traditional ADN preheating catalytic ignition technology, such as reliable and rapid ignition performance, no reliance on catalysts, flexible control range, low energy consumption and simple operation.

[0030] 3) The gelling agents used in this invention are sodium alginate and sodium carboxymethyl starch. Both gelling agents are water-soluble anionic polymers. The ionization of the anionic groups forms a strong ion-dipole interaction with water molecules, while the hydrophilic groups form hydrogen bonds with water, thereby promoting dissolution, improving the uniformity of the gel system, and thus significantly improving the combustion stability of the gel and enhancing the ignition capability of the gel propellant.

[0031] 4) The pectin molecular chains in the functional additives of this invention form a network through hydrogen bonds, which can stabilize fuel and oxidizer particles in the propellant and prevent sedimentation or separation. While not affecting the combustion performance of this gel propellant, it can enhance the propellant's adaptability, maintain good rheological characteristics, and enhance its atomization performance;

[0032] 5) The combustion products of the gel propellant produced using the scheme disclosed in this invention are clean and pollution-free, which conforms to the concept of green propulsion and reflects environmental friendliness;

[0033] 6) The process for preparing gel propellants based on the present invention is simple, low in cost, and easy to scale up for industrial production. Attached Figure Description

[0034] Figure 1This is a combustion sequence diagram of the propellant at 150V in Example 1 of the present invention.

[0035] Figure 2 This is a combustion sequence diagram of Example 1 of the present invention at 150V without the addition of functional additives.

[0036] Figure 3 This is a diagram showing the ignition delay time of the propellant under different voltages in Comparative Example 1 of the present invention.

[0037] Figure 4 This is a diagram showing the ignition delay time of the propellant under different voltages in Comparative Example 2 of the present invention.

[0038] Figure 5 This is a physical image of the gel propellant used in Comparative Example 4 of the present invention. Detailed Implementation

[0039] The present invention will now be described in detail with reference to specific embodiments, but the scope of protection is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention should be included within the scope of protection of the present invention.

[0040] This invention provides a green and clean ADN-based electro-gel propellant, the components of which include: ADN solution; ammonium nitrate; fuel; gelling agent; and functional additive components;

[0041] Based on the total mass of the gel propellant being 100%, the mass percentage content of each component is as follows:

[0042] ADN solution: 65% ~ 75%;

[0043] Ammonium nitrate: 10%–15%

[0044] Fuel: 10%–20%;

[0045] Gelling agent: 5%–10%;

[0046] Functional additives: 0.2%–2%.

[0047] The ADN solution has a mass fraction concentration of 75%. The fuel is one or a mixture of methanol and glycerol, both of analytical grade. The gelling agent is one or a mixture of sodium alginate and sodium carboxymethyl starch. Functional additives include thickeners and surfactants. The thickener is one or more of methylcellulose, ethylcellulose, and sodium carboxymethyl cellulose. The surfactant is pectin.

[0048] Example 1

[0049] (1) A green and clean ADN-based electro-controlled gel propellant, the formulation components and their mass fractions are shown in Table 1.

[0050] Table 1 Formulation Components of Example 1

[0051] Formulation components Content (%wt) ADN solution 65.9 Glycerol 13.7 ammonium nitrate 11.9 Sodium carboxymethyl starch 7.4 Methylcellulose 0.5 pectin 0.6

[0052] Weigh the raw materials according to the formula in Table 1;

[0053] A measured amount of ADN solution was weighed and mixed with glycerol. The mixture was then stirred under vacuum at 1000 rpm for 2 minutes at room temperature to obtain mixed propellant solution A. Ammonium nitrate was added to solution A and stirred under vacuum at 1500 rpm for 5 minutes at 40°C until the ammonium nitrate was completely dissolved to obtain mixed propellant solution B. Sodium carboxymethyl starch was added to solution B and sonicated for 5 minutes. The mixture was then stirred under vacuum at 2000 rpm for 20 minutes at 40°C until the gelling agent was fully swollen and the system was free of large particles to obtain a flowable viscous liquid C. Thickener methylcellulose and surfactant pectin were added to liquid C and stirred under vacuum at 2000 rpm for 20 minutes at 40°C until the system was homogeneous, free of bubbles, and lost its flowability. The resulting gel propellant was allowed to stand and cool to room temperature to obtain a uniform and stable gel propellant.

[0054] (2) Based on theoretical calculations, the performance indicators of the green and clean ADN-based electro-controlled gel propellant are as follows:

[0055] Theoretical specific impulse at 7.09 MPa: 216.2 s

[0056] Theoretical combustion chamber temperature: 1981.15K

[0057] Theoretical combustion products and their proportions: 28.8% H2O, 20.7% CO2, 26.8% N2, 23.7% H2

[0058] The combustion sequence diagram of the propellant at 150V in this embodiment is shown below. Figure 1 As shown

[0059] Example 2

[0060] (1) A green and clean ADN-based electro-controlled gel propellant, the formulation components and their mass fractions are shown in Table 2.

[0061] Table 2 Formulation Components Table of Example 2

[0062] Formulation components Content (%wt) ADN solution 65.8 Glycerol 5.3 methanol 7.6 ammonium nitrate 13.1 Sodium carboxymethyl starch 7.2 Ethyl cellulose 0.6 pectin 0.4

[0063] Weigh the raw materials according to the formula in Table 2;

[0064] Weigh out a measured amount of ADN solution, glycerol, and methanol, mix them, and vacuum stir for 2 minutes at 1000 rpm at room temperature to obtain mixed propellant solution A. Add ammonium nitrate to solution A and stir for 5 minutes at 1500 rpm at 40°C until the ammonium nitrate is completely dissolved to obtain mixed propellant solution B. Add sodium carboxymethyl starch gelling agent to solution B, sonicate for 5 minutes, and then stir for 20 minutes at 2000 rpm at 40°C until the gelling agent is fully swollen and there are no obvious large particles in the system to obtain a flowable viscous liquid C. Add ethyl cellulose thickener and pectin surfactant to liquid C and stir for 20 minutes at 2000 rpm at 40°C until the system is homogeneous, free of bubbles, and loses its flowability. Allow the obtained gel propellant to stand and cool to room temperature to finally obtain a uniform and stable gel propellant.

[0065] (2) Based on theoretical calculations, the performance indicators of the green and clean ADN-based electro-controlled gel propellant are as follows:

[0066] Theoretical specific impulse at 7.09 MPa: 233.6 s

[0067] Theoretical combustion chamber temperature: 2263.92K

[0068] Theoretical combustion products and proportions: 31.6% H2O, 19.4% CO2, 25.8% N2, 23.2% H2

[0069] Example 3

[0070] (1) A green and clean ADN-based electro-controlled gel propellant, the formulation components and their mass fractions are shown in Table 3.

[0071] Table 3 Formulation Components of Example 3

[0072] Formulation components Content (%wt) ADN solution 65.2 Glycerol 14.3 ammonium nitrate 11.2 Sodium alginate 5.6 Sodium carboxymethyl cellulose 3.1 pectin 0.6

[0073] Weigh the raw materials according to the formula in Table 3;

[0074] A measured amount of ADN solution was weighed and mixed with glycerol. The mixture was then stirred under vacuum at 1000 rpm for 2 minutes at room temperature to obtain mixed propellant solution A. Ammonium nitrate was added to solution A and stirred under vacuum at 1500 rpm for 5 minutes at 40°C until the ammonium nitrate was completely dissolved to obtain mixed propellant solution B. Sodium alginate was added to solution B and sonicated for 5 minutes. The mixture was then stirred under vacuum at 2000 rpm for 20 minutes at 40°C until the gelling agent was fully swollen and the system was free of large particles to obtain a flowable viscous liquid C. Sodium carboxymethyl cellulose and pectin were added to liquid C and stirred under vacuum at 2000 rpm for 20 minutes at 40°C until the system was homogeneous, free of bubbles, and lost its flowability. The resulting gel propellant was allowed to stand and cool to room temperature to obtain a uniform and stable gel propellant.

[0075] (2) Based on theoretical calculations, the performance indicators of the green and clean ADN-based electro-controlled gel propellant are as follows:

[0076] Theoretical specific impulse at 7.09 MPa: 236.9 s

[0077] Theoretical combustion chamber temperature: 2515.92K

[0078] Theoretical combustion products and their proportions: 39.4% H2O, 19.9% ​​CO2, 27.6% N2, 13.1% H2

[0079] Example 1 formulation consists of ADN solution, glycerol, ammonium nitrate, sodium carboxymethyl starch, methylcellulose, and pectin.

[0080] To study the effect of functional additives on propellant combustion performance, we used high-speed photography to obtain a sequence of combustion flame images. Figure 1 This is a combustion sequence diagram of the propellant at 150V in Embodiment 1 of the present invention. Figure 2 This is a combustion sequence diagram of Example 1 of the present invention at 150V without the addition of functional additives. (Comparison is needed.) Figure 1 and Figure 2 It can be concluded that the addition of functional additives enhances the stability of the flame shape during combustion and reduces the phenomenon of flameout or deflagration.

[0081] To further compare the effects of changes in formulation components on combustion performance, we set up Comparative Example 1 and Comparative Example 2.

[0082] Comparative Example 1

[0083] The components are the same as in Example 1, but the main oxidant is replaced with hydroxylamine nitrate and the auxiliary oxidant is replaced with lithium perchlorate.

[0084] Under the condition of maintaining a constant applied voltage, compared with the gel propellant of Comparative Example 1, the ignition delay time of the gel propellant of Example 1 showed a significant shortening trend during the combustion start-up phase. This difference directly reflects the advantage of Example 1 in ignition response speed. Further observation of the data change pattern shows that as the applied voltage gradually increases, the ignition delay time of the gel propellant of Example 1 shows a continuous and stable decreasing trend, reflecting the correlation between voltage parameters and the ignition delay characteristics of the propellant.

[0085] Comparative Example 2

[0086] The components are the same as in Example 1, but the main oxidant is replaced with hydroxylamine nitrate and the gelling agent is replaced with xanthan gum.

[0087] from Figure 4 Similar conclusions can be drawn, namely, under the same voltage, the ignition delay time of the gel propellant in Example 1 is reduced compared to that in Comparative Example 2, and the ignition delay time gradually decreases as the voltage increases.

[0088] Comparative Examples 1 and 2 reveal that the composite system of primary oxidant, secondary oxidant, fuel, gelling agent, and functional additives constructed in this application exhibits a clear core component dominance: the primary oxidant ADN, secondary oxidant ammonium nitrate, and gelling agent sodium carboxymethyl starch together form the key framework for performance assurance. Ammonium nitrate can reduce incomplete reactions during combustion by regulating the oxygen balance of the system, while the gelling agent sodium carboxymethyl starch ensures the uniformity of the system by controlling gel viscosity and dispersibility. Both provide fundamental support for the performance of combustion. The primary oxidant ADN is the core variable determining the quality of combustion performance. With its superior energy release efficiency, ADN can release chemical energy at a faster reaction rate during combustion, shortening the energy accumulation time in the ignition stage and increasing the energy output intensity of the combustion process. Therefore, it plays an irreplaceable and positive role in the formation and actual performance of good combustion performance of gel propellants.

[0089] To investigate the sequential steps in the preparation of gel propellants, Comparative Example 3 and Comparative Example 4 were set up.

[0090] Example 1

[0091] This invention discloses a method for preparing a green and clean ADN-based electro-controlled gel propellant, the method comprising the following steps:

[0092] 1) Mix the weighed ADN solution and fuel, and use a vacuum stirrer to stir under vacuum at 1000 r / min for 2 min at room temperature to obtain mixed propellant solution A;

[0093] 2) Add ammonium nitrate to the propellant mixture solution A obtained in step 1), and stir with a vacuum mixer at a constant temperature of 40℃ and a speed of 1500r / min for 5 minutes until the auxiliary oxidant is completely dissolved to obtain the mixed propellant solution B;

[0094] 3) Add the gelling agent to the propellant mixture solution B obtained in step 2), sonicate for 5 min, and stir with a vacuum mixer at a constant temperature of 40℃ and a speed of 2000 r / min for 20 min until the gelling agent is fully expanded and dissolved and there are no obvious large particles in the solution, to obtain a flowable viscous liquid C.

[0095] 4) Add thickener and surfactant to the flowable viscous liquid C obtained in step 3), and stir with a vacuum mixer at a constant temperature of 40℃ and a speed of 2000r / min for 20min until the gel propellant is uniform and free of bubbles and the system loses its fluidity.

[0096] 5) Cool the gel propellant obtained in step 4) to room temperature to obtain a uniform and stable gel propellant.

[0097] Comparative Example 3

[0098] Unlike the preparation process described above, step 3 precedes step 2. This change in order disrupts the rationality of the mixed solution system construction, resulting in the auxiliary oxidant failing to fully contact, wet, and uniformly disperse during subsequent mixing. In the subsequent combustion performance test, this non-uniform dispersion directly led to differences in combustion behavior. The small particle splashing during flame combustion was more severe than in Example 1. The splashed particles not only formed more obvious jet-like trajectories in the flame, but the splashing range was also expanded, adversely affecting both combustion efficiency and stability.

[0099] Comparative Example 4

[0100] Unlike the preparation process described above, step 3 is omitted. The gelling agent and functional additives from steps 3 and 4 are added to the mixed solution all at once and stirred uniformly, ultimately forming a gel. However, the microscopic uniformity of this gel is significantly insufficient. Figure 5 As shown, there may be particulate flocs. These flocs may not be fully dispersed or dissolved in the gel matrix due to factors such as the influence of material reaction compatibility, forming a locally uneven dispersion state. In the combustion test, this can cause the injection pump to clog, resulting in unstable or even completely interrupted propellant delivery flow, which seriously interferes with the continuity of the combustion test and the reliability of the test results.

[0101] Therefore, the synthesis process of this invention has strict requirements on the order of addition of each component. The synthesis steps require the oxidant and gelling agent to be added to the mixed solution sequentially, and finally the functional additive is added. After each addition, the stirring rate and time must be controlled to provide a stable and uniform reaction base for the subsequent gelation reaction. Otherwise, problems such as slow ignition response, large flame fluctuations, and low combustion efficiency will occur, seriously affecting the actual effect of the product. The above content is only an illustration of the preferred embodiment of this invention and is not intended to limit the scope of protection of this invention. It should be noted that any improvements, optimizations, or equivalent substitutions made by those skilled in the art without departing from the core principles of this invention should be included in the scope of protection of this invention.

Claims

1. A green and clean ADN-based electro-controlled gel propellant, characterized in that, The components of this electrically controlled gel propellant include: ADN solution; ammonium nitrate; fuel; gelling agent; and functional additive components. Based on the total mass of the gel propellant being 100%, the mass percentage content of each component is as follows: ADN solution: 65%~75%; Ammonium nitrate: 10%–15% Fuel: 10%–20%; Gelling agent: 5%–10%; Functional additives: 0.2%–2%.

2. The green and clean gel propellant according to claim 1, characterized in that: The ADN solution is the main oxidant, with a mass fraction concentration of 75%.

3. The green and clean gel propellant according to claim 1, characterized in that: The ammonium nitrate mentioned is a co-oxidizing agent.

4. The green and clean gel propellant according to claim 1, characterized in that: The fuel is one or both of methanol and glycerol.

5. The green and clean gel propellant according to claim 1, characterized in that: The gelling agent is one or both of sodium alginate and sodium carboxymethyl starch.

6. The green and clean gel propellant according to claim 1, characterized in that: The functional additives include thickeners and surfactants.

7. The green and clean gel propellant according to claim 6, characterized in that: The thickener is one or more of methylcellulose, ethylcellulose, and sodium carboxymethylcellulose.

8. The green and clean gel propellant according to claim 6, characterized in that: The surfactant mentioned is pectin.

9. The green and clean gel propellant according to claim 1, characterized in that: The components of this electro-controlled gel propellant are: 65.9% ADN solution, 13.7% glycerol, 11.9% ammonium nitrate, 7.4% sodium carboxymethyl starch, 0.5% methylcellulose, and 0.6% pectin.

10. A method for preparing the green and clean gel propellant according to any one of claims 1 to 9, characterized in that: The steps of this method include: 1) Mix the weighed ADN solution and fuel, and use a vacuum stirrer to stir under vacuum at 1000 r / min for 2 min at room temperature to obtain mixed propellant solution A; 2) Add ammonium nitrate to the propellant mixture solution A obtained in step 1), and stir with a vacuum mixer at a constant temperature of 40℃ and a speed of 1500r / min for 5 minutes until the auxiliary oxidant is completely dissolved to obtain the mixed propellant solution B; 3) Add the gelling agent to the propellant mixture solution B obtained in step 2), sonicate for 5 min, and stir with a vacuum mixer at a constant temperature of 40℃ and a speed of 2000 r / min for 20 min until the gelling agent is fully expanded and dissolved and there are no obvious large particles in the solution, to obtain a flowable viscous liquid C. 4) Add thickener and surfactant to the flowable viscous liquid C obtained in step 3), and stir with a vacuum mixer at a constant temperature of 40℃ and a speed of 2000r / min for 20min until the gel propellant is uniform and free of bubbles and the system loses its fluidity. 5) Cool the gel propellant obtained in step 4) to room temperature to obtain a uniform and stable gel propellant.

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