Three-electrode hydroxylammonium nitrate-based liquid propellant electrolytic preheating-electrolytic ignition method

Abstract

The application discloses a three-electrode hydroxylammonium nitrate-based liquid propellant electrolysis preheating-electrolysis ignition method and belongs to the fields of liquid rocket engines and electrochemistry. Three electrolysis electrodes, including two anodes and one cathode, are arranged in an electrolysis chamber to form two groups of electrolysis electrode pairs. After hydroxylammonium nitrate-based liquid propellant is injected into the electrolysis chamber, electrolysis preheating is started by electrifying one group of electrolysis electrode pairs; when a preset switching time is reached, the electrolysis electrode pairs currently working are turned off, and the electrolysis is continued by switching to another group of electrolysis electrode pairs which are not working; and low-voltage and fast electrolysis ignition is realized. The three-electrode electrolysis structure can shorten the time for ignition and for the reaction to reach the highest temperature, improve the system response speed, change the preheating and ignition voltage, has a large voltage adjustment and optimization space, has a relatively stable electrolysis ignition current, has a small instantaneous power consumption, can save electrolysis power consumption and reduce electrolysis electrode loss, and is favorable for the reuse of the electrodes.

Description

Technical Field

[0001] This invention relates to the fields of liquid rocket engines and electrochemistry, and particularly to a three-electrode method for electrolytic preheating and electrolytic ignition of hydroxylamine nitrate-based liquid propellants. Background Technology

[0002] Hydroxyllammonium nitrate (HAN) is a new generation of environmentally friendly, low-freezing-point, high-density green propellant. It is suitable as a replacement for highly toxic traditional hydrazine propellants, and its specific impulse is comparable to that of anhydrous hydrazine. Currently, the mainstream ignition method for hydroxylammonium nitrate-based liquid propellants is catalytic ignition. However, catalytic ignition has the following disadvantages: ① it cannot be cold-started, and the catalytic bed needs to be preheated; ② the catalyst deactivates, resulting in long ignition delay, high ignition difficulty, and poor reusability.

[0003] Based on the ionic liquid properties of hydroxylamine nitrate propellants, they can be electrolyzed and ignited by applying an electric current to induce an electrochemical reaction. Electrolytic ignition does not require a catalyst bed, is easy to ignite, has a short ignition delay, and is highly reusable. However, traditional dual-electrode electrolytic ignition still has the following drawbacks: ① When operating with certain specific electrolytic electrode areas, it may lead to a significant increase in electrolysis time; ② The power required for electrolysis, especially the instantaneous power, is relatively high. Summary of the Invention

[0004] To overcome the above problems, this invention proposes a three-electrode hydroxylamine nitrate liquid propellant electrolytic preheating-electrolytic ignition method, which uses three electrodes for preheating and then rapid ignition, effectively shortening the electrolytic ignition time.

[0005] The technical solution of the present invention is as follows:

[0006] A three-electrode method for electrolytic preheating and electrolytic ignition of hydroxylamine nitrate liquid propellant includes the following steps:

[0007] Three electrolytic electrodes are set in the electrolysis chamber, including two positive electrodes and one negative electrode, which constitute two sets of electrolytic electrode pairs (sharing a single negative electrode).

[0008] After the hydroxylamine nitrate liquid propellant is injected into the electrolysis chamber, a set of electrolysis electrodes is energized to start electrolysis preheating;

[0009] After the preset switching time is reached, the currently working electrolytic electrode pair is turned off, and the electrolysis is switched to another set of non-working electrolytic electrodes (which share the negative electrode with the first set of electrodes) to continue electrolysis. The fast-reading electrolytic ignition mode is activated until electrolytic ignition and combustion are completed, generating thrust.

[0010] Preferably, the effective area ratio of the positive electrode to the negative electrode of the electrolytic electrode is 0.5-2.0, and the length, width and thickness of the positive electrode and the negative electrode can be freely adjusted as needed.

[0011] Preferably, the working voltage is adjustable within the range of 30V-150V during the electrolysis step.

[0012] Preferably, the electrolyte solution is a hydroxylamine nitrate-based liquid propellant, comprising an aqueous solution of hydroxylamine nitrate and a mixed liquid propellant consisting of hydroxylamine nitrate and fuel.

[0013] Preferably, each pair of electrolytic electrodes is driven by an independent control circuit to achieve time-sharing energization and electrical isolation switching.

[0014] Preferably, the preset switching time is dynamically adjusted based on real-time feedback of electrolysis current or temperature.

[0015] Working principle analysis:

[0016] In the traditional dual-electrode low-voltage electrolytic ignition process, the chemical reactions occurring on the electrodes and in the solution can be roughly divided into three stages:

[0017] Phase 1: When a voltage is suddenly applied, the ions in the HAN solution (mainly including NO3-) - NH3OH + and H + The ions are rapidly attracted to the corresponding electrode surfaces, triggering a series of electrochemical reactions. These reactions include redox reactions that occur almost simultaneously at both the negative and positive electrodes, causing a rapid increase in both current and temperature. On the positive electrode side, an oxygen evolution reaction occurs, which is a four-electron transfer process in an acidic environment. On the negative electrode side, a hydrogen evolution reaction and a reduction reaction of nitrate ions occur.

[0018] Phase Two: Due to the attraction of the positive electrode to the anion, NO3... - Ions gradually move toward the positive electrode and cover the electrode surface, occupying active sites and reducing the positive electrode area participating in the reaction. This leads to the inhibition of the oxygen evolution reaction on the positive electrode side, resulting in a decrease in electrolysis current and a decrease in the chemical reaction rate.

[0019] Phase Three: After a relatively long electrolysis process, the solution temperature rises to approximately 420 K. Simultaneously, due to the nitrate ions (NO3-) in Phase Two... - The reduction reaction of ) produces more nitrite ions (NO2). - The thermal decomposition reaction of HAN is eventually triggered, resulting in electrolytic ignition.

[0020] From the above reaction process, it is not difficult to see that NO3 -The adsorption of ions at the positive electrode is a key factor leading to a reduced electrolysis rate and a longer electrolysis ignition time. Based on this, we designed an electrolysis preheating-electrolysis ignition device using three electrodes (sharing a single negative electrode). Its advantage lies in that, during the first and second stages of the electrolysis reaction, NO3-... - Ions are largely adsorbed on the initially working positive electrode; then switch to another set of electrodes that were not previously in use (which can share the negative electrode with the first set of electrodes). At this point, NO3 is not yet present on the newly connected positive electrode. - The adsorption of ions creates numerous activation sites, which can accelerate the electrolysis reaction.

[0021] The beneficial effects of this invention are:

[0022] The present invention provides a low-voltage electrolytic preheating-electrolytic ignition method for hydroxylamine nitrate-based liquid propellants using a three-electrode configuration. This method introduces three electrodes to form reusable grouped electrode pairs and employs an alternating switching mechanism. Utilizing the ionic liquid characteristics of hydroxylamine nitrate-based propellants, it retains the advantages of traditional electrolytic ignition, such as no need for catalytic preheating, short ignition delay, and high repeatability. Furthermore, it offers greater voltage adjustment flexibility, effectively shortens the time required for the electrolytic reaction to reach its maximum temperature, significantly improves system response speed, reduces the overall instantaneous electrolytic power required, and enhances the reusability of the electrode plates. This makes the present invention highly valuable for applications in aerospace propulsion and other scenarios requiring high-frequency, high-efficiency ignition. Attached Figure Description

[0023] Figure 1 This is a simplified diagram of a propulsion device shown in an embodiment of the present invention, wherein A is marked as... Figure 2 The cutting position of the sectional view;

[0024] Figure 2 This is a cross-sectional view of the combustion chamber of the propulsion device, showing the specific circumferential distribution of the three electrode plates; in the figure: 1-platinum positive electrode A, 2-platinum positive electrode B, 3-stainless steel negative electrode, distributed at 120° intervals along the circumference.

[0025] Figure 3 The figure shows the current-temperature-time curves during the electrolytic preheating-electrolytic ignition process of hydroxylamine nitrate liquid propellant using a three-electrode system, as illustrated in this embodiment of the invention. The solid black line in the figure represents the current-temperature-time curve for electrolytic ignition of hydroxylamine nitrate liquid propellant using a conventional two-electrode system, which requires a longer electrolytic ignition time. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the invention.

[0027] This invention provides a three-electrode method for electrolytic preheating and electrolytic ignition of hydroxylamine nitrate liquid propellant. This method utilizes three electrodes in the electrolysis chamber to form a reusable electrode pair, employing a time-sharing switching mechanism combined with parameter optimization and control strategies to achieve a highly efficient, low-power, and repeatable ignition process. The core of this solution lies in the synergistic effect of the multi-electrode structure and intelligent switching control, which significantly improves electrolytic ignition performance.

[0028] (1) Electrode structure and layout

[0029] Three electrolytic electrodes are installed in the electrolysis chamber, including a positive electrode (such as a platinum electrode) and a negative electrode (such as a stainless steel electrode). Different materials can be selected for the positive and negative electrodes to optimize electrolysis efficiency, depending on the requirements.

[0030] like Figure 1 and 2 As shown, the electrodes are distributed uniformly or non-uniformly along the circumference of the electrolysis chamber to ensure the uniformity of the electrolysis reaction and thermal management. For example, a 120° interval distribution can be used in a three-electrode system.

[0031] In this embodiment, the effective area ratio of the positive electrode to the negative electrode is controlled between 0.5 and 2.0. The length, width and thickness of the electrodes can be freely adjusted according to the electrolysis requirements to match the characteristics of different propellants.

[0032] (2) Electrolysis chamber and propellant injection

[0033] The electrolysis chamber is designed as a sealed container with an electrode fixing structure and a liquid inlet for injecting hydroxylamine nitrate-based liquid propellant, such as a 70% hydroxylamine nitrate solution.

[0034] After the hydroxylamine nitrate liquid propellant is injected into the electrolysis chamber, the electrolysis process is started through the control system.

[0035] (3) Electrode grouping and reuse mechanism, switching control

[0036] The electrodes are divided into two groups of electrode pairs (e.g., one group consists of platinum electrode A and a stainless steel electrode, and the other group consists of platinum electrode B and a stainless steel electrode). Different groups of electrode pairs can reuse the same electrode, such as using the stainless steel electrode as a common negative electrode. Each group of electrode pairs is controlled by an independent circuit to achieve electrical isolation and time-sharing energization.

[0037] After electrolysis is started, one set of electrode pairs works first, such as platinum electrode A and stainless steel electrode. After the preset switching time is reached (e.g., t1=10s), the current electrode pair is turned off and switched to another set of non-working electrode pairs, such as platinum electrode B and stainless steel electrode, to continue electrolysis.

[0038] In one specific embodiment of the present invention, the switching time can be dynamically adjusted based on real-time feedback, such as current feedback, temperature feedback, or a fixed time mode; the current feedback refers to monitoring changes in the electrolytic current and triggering switching when the current fluctuation exceeds a threshold; the temperature feedback refers to detecting the electrolyte temperature through a temperature sensor and adjusting the switching time according to the temperature rise rate; the fixed time mode refers to preset an optimized time interval based on experimental data, such as 10-30s.

[0039] In one specific embodiment of the present invention, the voltage is adjustable in the range of 30V-150V, and different electrode pairs before and after switching can use the same or different voltages.

[0040] In this embodiment, the steps of a three-electrode method for electrolytic preheating and electrolytic ignition of hydroxylamine nitrate liquid propellant are as follows:

[0041] S1, Initialization: Inject hydroxylamine nitrate propellant, set the electrode pair switching sequence and initial voltage.

[0042] S2, Start electrolysis: The first set of electrode pairs is energized. After the switching time is reached, the current electrode pair is automatically turned off and the next set of electrode pairs is activated to continue electrolysis.

[0043] S3, Termination: Power is supplied until the electrolyte temperature reaches its peak, ignition is complete, and the power is cut off.

[0044] Verification experiments were conducted to compare the effects of traditional dual-electrode electrolytic ignition and the three-electrode electrolytic ignition proposed in this invention. The experiments used two platinum metal sheets as positive electrodes, designated as platinum electrode A and platinum electrode B, and one stainless steel metal sheet as the negative electrode, also a stainless steel electrode. The three electrodes were evenly distributed at 120° circumferential angles. Figure 1 As shown, its parameters are as follows:

[0045]

[0046] As shown in the table, the effective area ratio of platinum electrode A and stainless steel electrode is different from that of platinum electrode A and stainless steel electrode; the former is smaller than the latter.

[0047] In the following experiments, the propellant used was 6g of 70% hydroxylamine nitrate solution, and the electrolysis voltage was 60V.

[0048] Traditional two-electrode mode experiment:

[0049] Slow-mode experiment: Only platinum electrode A and stainless steel electrode were connected to form a circuit to electrolyze the electrolyte. The obtained current and temperature data are as follows: Figure 3 As shown by the solid black line, the current response is gradual during electrolysis, the temperature rise rate is low, and the time required for the reaction to reach the maximum temperature is relatively long.

[0050] Multi-electrode switching mode experiment:

[0051] A dynamic switching experiment was conducted with a three-electrode configuration. The procedure was as follows: First, platinum electrode A and the stainless steel electrode were connected to form a circuit for electrolysis of the electrolyte. After a specific time t1 (10 s in the example), platinum electrode A was disconnected, and the circuit was switched to platinum electrode B, which then formed a circuit with the stainless steel electrode to continue electrolysis. After a specific time t2 (20 s in the example), platinum electrode B was disconnected again, and the circuit was switched back to platinum electrode A, which then formed a circuit with the stainless steel electrode to continue electrolysis. This alternating operation was repeated until electrolysis was completed. Data were recorded for five sets of different switching time parameters, such as... Figure 3 The solid lines in purple, red, blue, green, and orange are used to indicate this.

[0052] For ease of description, the ignition time in the traditional two-electrode electrolysis ignition experiment is defined as the time from the start of energization to the time when the solution reaches its maximum temperature, while the ignition time in the three-electrode electrolysis ignition experiment is defined as the time from the start of electrode switching to the time when the solution reaches its maximum temperature.

[0053] analyze Figure 3 Data shows that the multi-electrode switching mode does not affect the final maximum temperature, but it can affect the current electrolysis mode, significantly shortening the reaction time. Furthermore, with optimization of the switching time parameters, the ignition time gradually decreases. After switching, the system immediately inherits the electrolysis characteristics of the current electrode pair, proving that the reaction rate can be controlled in real time through dynamic electrode switching. The asymmetric electrode structure combined with the time-sharing switching strategy reduces overall power consumption while minimizing electrode polarization losses, providing a technical basis for repeated ignition.

[0054] Therefore, the electrolytic ignition method for hydroxylamine nitrate-based liquid propellant based on multiple electrodes provided by this invention can significantly shorten the time for the electrolytic reaction to reach the maximum temperature, improve the system response speed, achieve low-voltage ignition more quickly, and reduce the overall required electrolytic power.

[0055] The above description is merely a glimpse into the specific content and operation of this invention, but the scope of protection of this invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this invention should be included within the scope of protection of this invention. Therefore, the scope of protection of this invention should be determined by the scope of the claims.

Claims

1. A three-electrode method for electrolytic preheating-electrolytic ignition of hydroxylamine nitrate-based liquid propellant, characterized in that, Includes the following steps: Three electrolytic electrodes are set in the electrolysis chamber, including two positive electrodes and one negative electrode, which constitute two sets of electrolytic electrode pairs; After the hydroxylamine nitrate liquid propellant is injected into the electrolysis chamber, a set of electrolysis electrodes is energized to start electrolysis preheating; After the preset switching time is reached, the currently working electrolytic electrode pair is turned off, and the electrolysis is switched to another set of non-working electrolytic electrodes to continue electrolysis until electrolysis is completed and the propellant is ignited.

2. The three-electrode hydroxylamine nitrate liquid propellant electrolytic preheating-electrolytic ignition method according to claim 1, characterized in that, The effective area ratio of the positive to negative electrode of the electrolytic electrode is 0.5-2.

0.

3. The three-electrode hydroxylamine nitrate liquid propellant electrolytic preheating-electrolytic ignition method according to claim 1, characterized in that, During the electrolysis process, the working voltage is adjustable within the range of 30V-150V.

4. The three-electrode hydroxylamine nitrate liquid propellant electrolytic preheating-electrolytic ignition method according to claim 1, characterized in that, The electrolyte solution is a hydroxylamine nitrate-based liquid propellant, comprising an aqueous solution of hydroxylamine nitrate and a mixed liquid propellant composed of hydroxylamine nitrate and fuel.

5. The three-electrode hydroxylamine nitrate liquid propellant electrolytic preheating-electrolytic ignition method according to claim 1, characterized in that, Each pair of electrolytic electrodes is driven by an independent control circuit, enabling time-sharing energization and electrical isolation switching.

6. The three-electrode hydroxylamine nitrate liquid propellant electrolytic preheating-electrolytic ignition method according to claim 1, characterized in that, The preset switching time is dynamically adjusted based on real-time feedback of electrolysis current or temperature.

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