Ammonia fuel modified fusion fuel preparation system and fuel verification method

Abstract

The invention discloses an ammonia fuel modified fusion fuel preparation system and a fuel verification method. The system comprises a gas supply unit, an ammonia supply unit, an ammonia-hydrogen mixing unit, an ammonia-hydrogen aftertreatment unit, a fuel injector and a fuel verification unit. The ammonia-hydrogen mixing unit injects hydrogen and liquid ammonia into the ammonia-hydrogen mixing unit to form liquid ammonia-hydrogen fused fuel; an outlet of the ammonia-hydrogen mixing unit is respectively communicated with the ammonia-hydrogen post-processing unit, the fuel injector and the outside; and the ammonia-hydrogen post-treatment unit absorbs ammonia gas from the ammonia-hydrogen mixing unit and the fuel injector, and then hydrogen purification and storage are carried out. The fuel verification unit is used for receiving and measuring the fuel ejected from the fuel injector so as to verify the hydrogen content of the fuel; and comparing the actually obtained hydrogen content with the preset theoretical hydrogen content of the fusion fuel to verify the influence of pressure fluctuation caused in the fusion fuel application process on the actual value of the hydrogen solubility, thereby preparing the corresponding ammonia-hydrogen fusion fuel according to the working requirements of different ammonia-hydrogen engines.

Description

Technical Field

[0001] This invention relates to the field of internal combustion engine technology, specifically to a fusion fuel preparation system and fuel verification method that modifies and upgrades ammonia fuel. Background Technology

[0002] Global warming caused by greenhouse gases has led to more frequent extreme weather events, seriously threatening human living space. Ammonia (NH3), as a zero-carbon fuel, has a mature production process, is easy to store and transport, and is considered a highly promising hydrogen energy carrier, making it an important candidate for achieving net-zero greenhouse gas emissions from marine propulsion. However, the high ignition point, low reactivity, and low laminar flame velocity of ammonia fuel limit its use as a single fuel in internal combustion engines, especially in marine engines that prioritize high efficiency and stability. Currently, the mainstream stable ignition and combustion technology for ammonia-fueled engines involves installing ignition fuel injectors to utilize highly reactive hydrocarbon fuels, such as diesel and dimethyl ether, to form a compression ignition flame in the engine, igniting the difficult-to-ignite ammonia fuel. However, the carbon dioxide produced by the combustion of hydrocarbon fuels hinders decarbonization in the engine industry, and the ignition fuel injectors installed on the engine cylinder head further increase the complexity of the engine's fuel supply system, injection system, and cylinder head structure. Especially under low load conditions, due to the low total calorific value of fuel, it is impossible to ignite the extremely low diesel energy ratio, lacks the ability to regulate combustion, and can hardly ignite the ammonia jet, resulting in unstable engine combustion and severely restricting the engine's reliability and adaptability.

[0003] To overcome the combustion defects of ammonia fuel, existing technologies have proposed several solutions. CN115111089B discloses a pre-combustion chamber ammonia fuel engine system. Its core technology involves catalytically decomposing a portion of the ammonia fuel using exhaust waste heat or electric heating to produce hydrogen. The hydrogen is then injected into the pre-combustion chamber for ignition, and the resulting high-energy jet flame ignites the ammonia fuel in the main combustion chamber. This engine system relies on a complete chain of catalytic decomposition, hydrogen separation, and purification. This process exhibits thermal inertia, resulting in a slow dynamic response to changes in engine operating conditions, making it difficult to achieve precise and rapid control of the hydrogen / ammonia ratio under transient conditions. Ammonia cracking for hydrogen production requires energy, and the temperature generated by engine exhaust is insufficient for ammonia cracking, necessitating additional energy. CN115234369B discloses an ammonia-hydrogen fusion fuel diffusion combustion control system based on reactivity regulation. It creates a highly reactive hydrogen-air premixed gas by directly injecting hydrogen into the main combustion chamber, which then mixes with injected ammonia fuel to form an ammonia-hydrogen fusion fuel. The turbulent jet flame generated in the pre-combustion chamber ignites the ammonia-hydrogen mixture in the cylinder, resulting in diffusion combustion. This technology indicates that producing hydrogen through ammonia cracking requires additional energy input, leading to energy loss. Adding a hydrogen storage tank increases space utilization costs. Furthermore, configuring two injection systems for ammonia and hydrogen increases the design complexity of the cylinder head. If a mixed gas is used for storage, according to the law of partial pressures, the saturated vapor pressure of ammonia at room temperature is 1 MPa, while the storage pressure of hydrogen is 35 MPa. Therefore, the proportion of ammonia in the mixture must not exceed 1 / 35; otherwise, the ammonia will liquefy and cannot be injected into the cylinder in gaseous form. Existing technologies attempt to improve the combustion characteristics of ammonia fuel by introducing hydrogen, often employing the approach of "first cracking to produce hydrogen, then injecting it separately" or "in-cylinder mixing." Under current fuel supply technologies, it is difficult to ensure a balance between stable ammonia ignition and combustion, engine economy, clean combustion, and decarbonization and emission reduction, which poses a significant obstacle to the future development of green, clean, and efficient marine internal combustion engine power.

[0004] Compared to the automotive and aerospace industries, marine propulsion systems offer advantages such as unrestricted space and load capacity, larger engine size, and more stringent boundary conditions. Current combustion technologies for marine engines tend to favor high-pressure direct injection ammonia fuel diffusion combustion based on the Diesel cycle. To this end, an ammonia modification method based on ammonia-hydrogen dissolution theory is considered, aiming to prepare a liquid ammonia-hydrogen mixed fuel. This enhances the ignition reactivity of ammonia, thereby strengthening the engine's overall combustion stability and adaptability to multiple boundary conditions. Without altering existing intake boundary conditions and compression ratios, this research aims to develop an advanced combustion technology that achieves extremely low hydrocarbon fuel consumption, potentially even eliminating dependence on hydrocarbon fuels and achieving net-zero greenhouse gas emissions. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention proposes a fusion fuel preparation system and fuel verification method for ammonia fuel modification. This invention utilizes the dissolution of hydrogen in liquid ammonia to prepare ammonia-hydrogen fuel. Furthermore, a closed-loop method of "preparation-verification-comparison-correction" is used to ultimately ensure the correctness of the proportions, thereby preparing corresponding ammonia-hydrogen fusion fuels for different ammonia-hydrogen engines. In the prepared fusion fuel, hydrogen is dissolved in liquid ammonia in molecular form, resulting in a uniform distribution of hydrogen molecules within the liquid ammonia, improving the activity of the liquid ammonia spray, and lowering the fuel's ignition threshold.

[0006] The first aspect of this invention is to provide a fusion fuel preparation system for ammonia fuel modification, including a gas supply unit, an ammonia supply unit, an ammonia-hydrogen mixing unit, an ammonia-hydrogen aftertreatment unit, a fuel injector, and a fuel verification unit.

[0007] The gas supply unit is used to provide hydrogen or purging gas;

[0008] The ammonia supply unit is used to supply liquid ammonia;

[0009] The ammonia-hydrogen mixing unit includes a pressure-bearing sealed container for mixing liquid ammonia from the ammonia supply unit with hydrogen from the gas supply unit inside the pressure-bearing sealed container to form liquid ammonia-hydrogen fusion fuel; the inlet of the pressure-bearing sealed container is connected to the gas supply unit and the ammonia supply unit respectively; its outlet is connected to the ammonia-hydrogen after-treatment unit, the fuel injector and the outside respectively.

[0010] The fuel injector has its fuel inlet connected to the outlet of the ammonia-hydrogen mixing unit via a pipeline for injecting the prepared ammonia-hydrogen fused fuel; the fuel injector's return port is connected to the ammonia-hydrogen after-treatment unit.

[0011] The ammonia-hydrogen aftertreatment unit includes an ammonia aftertreatment device and a hydrogen recovery device. The inlet of the ammonia aftertreatment device is connected to both the outlet of a pressure-sealed container and the fuel injector return port. The ammonia aftertreatment device is used to chemically react the incoming ammonia- and / or hydrogen-containing mixed gas or liquid ammonia-hydrogen fusion fuel with a weak acid solution within it, absorbing the ammonia gas, and then passing the remaining hydrogen-containing mixed gas through a pipeline into the hydrogen recovery device. The hydrogen recovery device uses physical adsorption and filtration to purify the gas from the ammonia aftertreatment device, separating and recovering hydrogen.

[0012] The fuel verification unit is used to receive and measure the fuel injected from the fuel injector to verify its hydrogen content; compare the actual hydrogen content with the theoretical hydrogen content of the preset fusion fuel to verify the impact of pressure fluctuations caused during the application of the fusion fuel on the actual value of hydrogen solubility, and then prepare corresponding ammonia-hydrogen fusion fuels for different ammonia-hydrogen engines.

[0013] Specifically, the impact of pressure fluctuations caused during the verification of the application of the fusion fuel on the actual value of hydrogen solubility refers to the impact of pressure fluctuations caused during the pressurization of the liquid ammonia pump, the lifting of the fuel injector needle valve, and the establishment of pressure at the nozzle on the actual value of hydrogen solubility. In order to prepare suitable ammonia-hydrogen fusion fuels in a targeted manner for the minimum hydrogen content required by ammonia-hydrogen engines with different operating modes.

[0014] Furthermore, the ammonia-hydrogen mixing unit also includes a pressure sensor and a valve assembly; the pressure sensor is disposed inside the pressure-bearing sealed container to monitor its internal pressure; the valve assembly is electrically connected to a computer to control the opening / closing of the corresponding valve assembly based on the feedback from the pressure sensor and the control commands from the computer, thereby realizing overpressure protection and automatic pressure regulation of the pressure-bearing sealed container;

[0015] The valve assembly includes a first solenoid valve, a third solenoid valve, a pressure limiting valve, and a pressure relief valve;

[0016] The pressure relief valve is installed on the pipeline between the pressure-bearing sealed container and the ammonia hydrogen post-treatment unit. It opens when the pressure inside the pressure-bearing sealed container exceeds a preset safety threshold to safely release pressure.

[0017] The pressure relief valve is located on another pipeline between the pressure-bearing sealed container and the ammonia-hydrogen post-treatment unit, and is controlled by the computer to open in order to discharge liquid ammonia;

[0018] The first solenoid valve is installed on the pipeline between the pressure-bearing sealed container and the gas supply unit, and is controlled by the computer to open, so that the hydrogen / purge gas from the gas inlet unit is introduced into the pressure-bearing sealed container.

[0019] The third solenoid valve is installed on the pipeline between the pressure-bearing sealed container and the fuel injector, and is used to deliver the fused fuel prepared in the pressure-bearing sealed container into the fuel injector.

[0020] Furthermore, the valve assembly also includes a manual pressure relief valve and a fourth solenoid valve; the manual pressure relief valve connects the pressure-bearing sealed container and the outdoor atmosphere / ammonia aftertreatment device, and is used to discharge the gas in the pressure-bearing sealed container by means of exhaust; the fourth solenoid valve connects the pressure-bearing sealed container and the ammonia aftertreatment device, and is opened by computer control during the purging gas purging and hydrogen filling process.

[0021] In a more preferred embodiment, the fourth solenoid valve is positioned diagonally opposite the first solenoid valve.

[0022] Furthermore, the hydrogen recovery device is equipped with a hydrogen molecular sieve for separating and purifying hydrogen from the gas after ammonia absorption.

[0023] Furthermore, the system also includes a hydrogen recovery circuit, which includes a gas pump and a hydrogen pressure stabilizing tank. The inlet of the gas pump is connected to the outlet of the hydrogen recovery device, and the outlet of the gas pump is connected to the inlet of the hydrogen pressure stabilizing tank. The outlet of the hydrogen pressure stabilizing tank is connected to the gas supply unit, so that the recovered hydrogen can be sent back to the ammonia-hydrogen mixing unit for recycling.

[0024] Furthermore, the ammonia supply unit includes a liquid ammonia pump and a high-pressure oil pipe; the high-pressure oil pipe is connected to the inlet of the pressure-bearing sealed container through a second solenoid valve, and a multi-hole spray pipe is connected inside the pressure-bearing sealed container for spraying and atomizing the liquid ammonia from the high-pressure oil pipe.

[0025] Furthermore, the fuel verification unit includes a non-pressurized sealed container, inside which a hydrogen sensor is installed to detect the hydrogen concentration in the injected fuel; a mass scale is installed at the bottom of the non-pressurized sealed container to weigh the total mass of the injected fuel; and the nozzle of the fuel injector extends into the non-pressurized sealed container.

[0026] Furthermore, the ammonia post-treatment device is equipped with an ammonia leak alarm to monitor the residual ammonia concentration in the gas discharged after absorption by the weak acid solution, and to issue an alarm when the concentration exceeds the limit.

[0027] Furthermore, the gas supply unit includes a hydrogen source and a nitrogen source, as well as a four-way valve; the first port and the second port of the four-way valve are respectively connected to the hydrogen source and the nitrogen source, the third port is connected to the gas inlet of the ammonia-hydrogen mixing unit, and the fourth port is connected to the hydrogen recovery circuit.

[0028] A second aspect of the present invention is to provide a fuel validation method for the ammonia fuel reforming and modification fusion fuel preparation system, comprising:

[0029] Step 1: Pre-set the theoretical hydrogen solubility of the fused fuel. Based on the ammonia-hydrogen dissolution test data, obtain the pressure and temperature conditions required to produce the fused fuel with the pre-set hydrogen-ammonia content ratio. First, open the first solenoid valve 4 and the fourth solenoid valve 9, and use the purging gas from the gas supply unit to purge the pressure-bearing sealed container 11. Then, use hydrogen from the gas supply unit to purge the purging gas inside the pressure-bearing sealed container 11. After that, fill the pressure-bearing sealed container 11 with hydrogen until the pressure inside the pressure-bearing sealed container 11 reaches the preset initial pressure value, then proceed to Step 2:

[0030] Step 2: Close the first solenoid valve 4. Liquid ammonia from the ammonia supply unit enters the pressure-bearing sealed container 11 through the second solenoid valve 6 in the form of a spray at a preset initial pressure value. Then, according to the target pressure for preparing fused fuel preset in Step 1, liquid ammonia is injected into the pressure-bearing sealed container in stages. After each stage of injection, the container is allowed to stand to allow the hydrogen in the pressure-bearing sealed container 11 to dissolve in the liquid ammonia. The pressure of the liquid ammonia injected in each stage increases incrementally until the pressure inside the container reaches the final target pressure. Then, the container is allowed to stand for a sufficient time to allow the ammonia and hydrogen to fully fuse and form ammonia-hydrogen fused fuel.

[0031] Step 3: The ammonia-hydrogen fusion fuel formed after settling is quantitatively injected into the fuel verification unit through a fuel injector; the fuel verification unit is used to separate liquid ammonia and hydrogen, and the total mass of liquid ammonia and the hydrogen concentration are measured to calculate the actual hydrogen solubility to verify its hydrogen content; the actual hydrogen solubility is compared with the theoretical hydrogen solubility set in Step 1 to verify the impact of pressure fluctuations caused by the prepared fusion fuel during the current application of the ammonia-hydrogen engine on the actual value of hydrogen solubility; if they are inconsistent, return to Step 1 to modify the theoretical hydrogen solubility, thereby preparing the corresponding ammonia-hydrogen fusion fuel according to the current working requirements of the ammonia-hydrogen engine.

[0032] Furthermore, step two analyzes the specific process of pressurized fusion, including:

[0033] Starting from the initial pressure, liquid ammonia is injected into the pressure-bearing sealed container in multiple pressure steps. The operation of each pressure step includes: starting the liquid ammonia pump to increase the liquid ammonia pressure to the target value, opening the second solenoid valve 6 to spray high-pressure liquid ammonia into the container, and closing the second solenoid valve 6 when the pressure in the container reaches the target pressure of the pressure step, stopping the injection and allowing it to stand; then proceeding to the next higher pressure step until the final target pressure is reached.

[0034] Furthermore, after the injection verification in step three, the process also includes: releasing the remaining fused fuel in the pressure-sealed container, and purging the container with purging gas to remove residual hydrogen and perform post-treatment.

[0035] The beneficial effects of this invention are as follows:

[0036] This invention fundamentally solves the stability problem in the ammonia-hydrogen fuel preparation process by integrating a fusion fuel preparation system with a closed-loop verification method. This invention does not aim to completely eliminate pressure fluctuations during the dynamic preparation process, but rather ensures the correctness of the ratio through a closed-loop method of "preparation-verification-comparison-correction". Even if a small amount of hydrogen is released due to pressure fluctuations during the preparation process, this invention can accurately measure the hydrogen solubility of the actual prepared fuel through the final verification step.

[0037] Furthermore, this invention compares measured values ​​with theoretical values ​​and determines whether the prepared fusion fuel meets the preset requirements by measuring the hydrogen content; if the ratio is not in line due to factors such as pressure fluctuations, it can provide feedback and correct the initial parameters for the next preparation, and through iterative methods, finally prepare fusion fuel that meets the preset ratio.

[0038] Moreover, in the prepared fusion fuel, hydrogen is dissolved in liquid ammonia in molecular form, which makes hydrogen molecules evenly distributed in the liquid ammonia, improves the activity of liquid ammonia spray, and reduces the ignition threshold of the fuel. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the ammonia fuel modification and fusion fuel preparation system described in this invention.

[0040] Among them, 1: Hydrogen pressure reducing valve; 2: Nitrogen pressure reducing valve; 3: Four-way valve; 4: First solenoid valve; 5: Pressure sensor; 6: Second solenoid valve; 7: Hydrogen leak alarm; 8: Third solenoid valve; 9: Fourth solenoid valve; 10: Perforated spray pipe; 11: Pressure-bearing sealed container; 12: Pressure limiting valve; 13: Pressure relief valve; 14: Liquid ammonia pump; 15: Liquid ammonia pressure reducing valve; 16: High-pressure oil pipe; 17: Pressure regulating oil circuit; 18: Hydrogen sensor; 19: Non-pressure-bearing sealed container; 20: Weighing scale; 21: Ammonia after-treatment device; 22: Hydrogen recovery device; 23: Outdoor atmosphere; 24: Fuel injector; 25: Computer; 26: Air pump; 27: Pressure gauge; 28: Hydrogen pressure stabilizing chamber; 29: Manual pressure relief valve. Detailed Implementation

[0041] To make the objectives, technical solutions, beneficial effects, and significant advancements of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings provided in the examples of the present invention. Obviously, all the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] In the description of this application, unless otherwise expressly specified and limited, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more; unless otherwise specified or explained, the terms "connected," "fixed," etc., should be interpreted broadly. For example, "connected" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0043] like Figure 1 As shown, a fusion fuel preparation system for ammonia fuel modification includes a gas supply unit, an ammonia supply unit, an ammonia-hydrogen mixing unit, an ammonia-hydrogen aftertreatment unit, a fuel injector 24, and a fuel verification unit.

[0044] like Figure 1 The area marked by the blue dashed box indicates that the gas supply unit includes a hydrogen cylinder, a nitrogen cylinder, and gas pipelines, all made of stainless steel. The gas pipelines are equipped with a hydrogen pressure reducing valve 1, a nitrogen pressure reducing valve 2, and a four-way valve 3. One end of the hydrogen cylinder is connected to the four-way valve 3 via the hydrogen pressure reducing valve 1, and the other end of the nitrogen cylinder is connected to the four-way valve 3 via the nitrogen pressure reducing valve 2. The other end of the four-way valve 3 is connected to the hydrogen pressure regulating chamber 28 via a solenoid valve; the other end of the four-way valve 3 is connected to the inlet of the pressure-bearing sealed container 11 via an inlet solenoid valve 4. The hydrogen pressure reducing valve 1 is located at the hydrogen cylinder outlet, and the nitrogen pressure reducing valve 2 is located at the nitrogen cylinder outlet. The hydrogen pressure reducing valve 1, nitrogen pressure reducing valve 2, and four-way valve 3 are electrically connected to a computer for opening / closing under computer control.

[0045] like Figure 1 The area marked by the red dashed box in the middle describes the ammonia supply unit, which includes a liquid ammonia cylinder, a liquid ammonia pump 14, and a high-pressure oil pipe 16. The liquid ammonia cylinder is connected to the inlet of the liquid ammonia pump 14 via a pipeline, and a liquid ammonia pressure reducing valve 15 is installed on the pipeline between the outlet of the liquid ammonia cylinder and the liquid ammonia pump 14. The outlet of the liquid ammonia pump 14 is connected to one end of the high-pressure oil pipe 16, and the other end of the high-pressure oil pipe 16 is connected to a pressure-bearing sealed container 11 via a pipeline. A liquid ammonia inlet solenoid valve 6 is installed on the high-pressure oil pipe 16.

[0046] The ammonia-hydrogen mixing unit has overpressure protection and automatic pressure regulation functions, and includes the pressure-bearing sealed container 11 and valve assembly. Figure 1 The interior of the pressure-bearing sealed container 11 shown is divided into a green part and a yellow part from top to bottom, wherein the green part is a gas layer and the yellow part is a mixed fuel layer.

[0047] The pressure-bearing sealed container 11 includes seven openings in a clockwise direction: a first opening, a second opening, a third opening, a fourth opening, a fifth opening, a sixth opening, and a seventh opening. The first opening is connected to the outside atmosphere 23 via a manual pressure relief valve 29; the second opening is connected to the air intake unit via a first solenoid valve 4; the third opening is connected to the ammonia supply unit via a second solenoid valve 6; and the fourth opening is connected to the ammonia-hydrogen post-treatment unit via a pressure limiting valve 12. The air pump 26 pressurizes the hydrogen filtered by the hydrogen recovery device 22 and stores it in the hydrogen pressure stabilizing tank 28 for reuse.

[0048] The fifth opening connects to the ammonia-hydrogen aftertreatment unit via pressure relief valve 13. The sixth opening connects to the ammonia-hydrogen aftertreatment unit sequentially via the fourth solenoid valve 9 and the hydrogen leak alarm 7. The seventh opening connects to the fuel inlet of the fuel injector 24 via the third solenoid valve 8.

[0049] Pressure sensor 5 is installed at the top of the inner wall of the pressure-bearing sealed container 11, and can interact with... Figure 1 The green part of the gas layer is in contact.

[0050] When an operational error occurs and the pressure sensor 5 detects that the pressure in the pressure-bearing sealed container 11 exceeds a preset limit, the pressure-limiting valve 12 automatically opens for tight pressure relief. Since the pressure relief stops when the pressure in the pressure-bearing sealed container 11 drops to the pressure threshold of the pressure-limiting valve 12 during emergency pressure relief, no phase change occurs in the liquid fuel mixture. Only hydrogen is discharged from the pressure-limiting valve 12 and recovered after filtration by the hydrogen recovery device 22. At this time, because hydrogen is discharged from the pressure-bearing sealed container 11, a pressure drop is achieved during overpressure, meeting the requirements for safe production.

[0051] The ammonia-hydrogen aftertreatment unit includes an ammonia aftertreatment device 21 and a hydrogen recovery device 22. The pressure relief valve 12 and the fourth solenoid valve 9 are both connected to the inlet of the hydrogen recovery device 22 via pipelines. The outlet of the hydrogen recovery device 22 is connected in sequence via pipelines to a gas pump 26 and a hydrogen pressure stabilizing chamber 28, and then enters the intake unit via a solenoid valve. The pressure relief valve 13 and the return port of the fuel injector 24 are both connected to the inlet of the ammonia aftertreatment device 21 via pipelines. The ammonia-hydrogen mixed fuel from the fuel injector 24 enters the ammonia aftertreatment device 21 via the return port. The outlet of the ammonia aftertreatment device 21 is connected to the inlet of the hydrogen recovery device 22 via pipelines.

[0052] The ammonia aftertreatment device 21 includes a sealed container with two air inlets and one exhaust outlet. The sealed container contains an oxalic acid solution, which reacts with the incoming gas to absorb ammonia. The remaining hydrogen is then piped into a hydrogen recovery device 22 to prevent residual ammonia molecules from causing impurities in the recovered hydrogen. One air inlet of the ammonia aftertreatment device 21 is connected to a pressure relief valve 13. When it is necessary to discharge the mixed fuel from the pressurized sealed container 11, the pressure relief valve 13 is opened, discharging the mixture into the ammonia aftertreatment device 21 for ammonia aftertreatment and hydrogen recovery. Another air inlet of the ammonia aftertreatment device 21 is connected to the return port of the fuel injector 24. When the liquid mixed fuel in the pressure-sealed container 11 is injected into the fuel injector 24, the mixed fuel will flow out from the return port of the fuel injector at low pressure (i.e., the blue pipe next to the injector) to create a pressure difference. It then enters the ammonia aftertreatment device 21 through the pipe. The mixed fuel first enters the first sealed container, where the ammonia is absorbed by the oxalic acid solution. To prevent ammonia leakage, the mixed fuel then enters the second sealed container, where the oxalic acid solution again absorbs the ammonia from the mixed fuel. The other air inlet is connected to the pressure relief valve 13 through a pipe, absorbing the ammonia from the mixed fuel discharged from the pressure relief valve 13 in the same way as described above, preventing ammonia leakage.

[0053] The exhaust port of the ammonia post-treatment device 21 is connected to the inlet of the hydrogen recovery device 22 via a pipeline. An ammonia leak alarm is installed at the connection between the top of the second sealed container and the exhaust port. If the ammonia is not completely absorbed in the second sealed container, the alarm on the top of the ammonia post-treatment device 21 will be triggered, and the red light of the alarm will flash and a siren will sound. At this time, the oxalic acid solution should be replaced in time.

[0054] The hydrogen recovery device 22 includes a cylindrical shell, inside which, from top to bottom, are arranged a porous support plate, a hydrogen molecular sieve, an inert alumina sphere layer, and a metal mesh layer. A spring is installed between the porous support plate and the top of the shell to provide elasticity to the porous support plate; under the action of the spring, the porous support plate compresses the hydrogen molecular sieve downwards. The hydrogen molecular sieve allows smaller hydrogen molecules to pass through while absorbing larger molecules such as nitrogen, ammonia, oxygen, and water. The inert alumina sphere layer is 50-200 mm thick and filled with inert alumina spheres, which disperse the airflow and prevent the molecular sieve from directly impacting the support mesh, thus preventing pulverization. The metal mesh layer consists of multiple stacked metal mesh layers, which work in conjunction with the porous support plate to compress the molecular sieve and prevent it from shifting under pressure waves. When the mixed gas passes through the molecular sieve, large molecules are absorbed and temporarily stored by the sieve, while hydrogen also flows through the molecular sieve to the gas pump 26 and is pressurized and injected into the hydrogen pressure stabilizing chamber 28. During secondary experiments, the hydrogen can be used as purging nitrogen or to fill the pressure-bearing sealed container 11. Hydrogen recovery saves experimental materials, ensures experimental safety, and aligns with environmental protection principles.

[0055] The valve assembly includes a manual pressure relief valve 29, a first solenoid valve 4, a second solenoid valve 6, a third solenoid valve 8, a fourth solenoid valve 9, a pressure limiting valve 12, and a pressure relief valve 13. All valve bodies are electrically connected to a computer 25 and are opened / closed under its control.

[0056] The manual pressure relief valve 29 connects the pressure-bearing sealed container 11 to the outdoor atmosphere / ammonia after-treatment device 21. When the pressure relief valve 13 malfunctions or the system needs to be stopped urgently, the gas in the pressure-bearing sealed container 11 is discharged by venting. Figure 1The diagram only shows the manual pressure relief valve 29 discharging air. The manual pressure relief valve 29 may also optionally be connected to the ammonia aftertreatment device 21. The fourth solenoid valve 9 is located diagonally opposite the first solenoid valve 4. The first solenoid valve 4 allows hydrogen / nitrogen from the intake unit to enter the pressure-bearing sealed container 11; the fourth solenoid valve 9 connects the pressure-bearing sealed container 11 to the hydrogen recovery device 22, and is computer-controlled to open or close during nitrogen purging and hydrogen filling processes, allowing gas to exit the tank or ensuring an increase in hydrogen pressure within the tank. The second solenoid valve 6 is computer-controlled to open, allowing high-pressure liquid ammonia in the high-pressure oil pipe 16 to be sprayed into the pressure-bearing sealed container 11 through a porous spray pipe 10, thus facilitating mixing. The porous spray pipe 10 increases the contact area between liquid ammonia and hydrogen, promoting hydrogen dissolution. After the mixed fuel is prepared, the third solenoid valve 8, computer-controlled, injects the mixed fuel into the fuel injector 24, which then sprays it out. The pressure relief valve 12, acting as a safety valve, opens instantly when the pressure in the pressure-bearing sealed container 11 exceeds a preset threshold, rapidly venting gas from the tank and ensuring experimental safety. The pressure relief valve 13, used by the computer 25, automatically controls the pressure during the injection and pressurization of liquid ammonia into the pressure-bearing sealed container 11. When the pressure exceeds a set value, it releases a portion of the liquid ammonia, reducing the pressure inside the tank. The liquid ammonia outlet solenoid valve 8, controlled by the computer 25, opens after the mixed fuel preparation is complete, discharging the liquid-phase mixed fuel from the pressure-bearing sealed container 11.

[0057] The fuel verification unit includes a non-pressurized sealed container 19, inside which a hydrogen sensor 18 is installed, and a high-precision mass scale 20 is installed at its bottom. The bottom of the fuel injector 24 extends into the non-pressurized sealed container 19.

[0058] The method for verifying fusion fuels using the aforementioned fusion fuel preparation system includes:

[0059] Step 1: Preprocessing stage

[0060] The hydrogen-ammonia content ratio in the fused fuel is preset (i.e., the theoretical hydrogen solubility). Based on ammonia-hydrogen dissolution test data, the pressure and temperature conditions required to produce the fused fuel with the preset hydrogen-ammonia content ratio are obtained. Since the compressibility of liquids is very low (<2%), liquid ammonia is considered an incompressible fluid in the calculations; therefore, a certain volume of liquid ammonia corresponds to a certain mass of liquid ammonia. Based on the volume of the pressure-bearing sealed container 11, the mass of liquid ammonia when the container is filled is calculated, and thus the required mass of hydrogen is calculated. According to the ideal state equation, the minimum hydrogen pressure required to prepare the preset fused fuel can be calculated. Therefore, when filling with hydrogen, the hydrogen pressure simply needs to exceed this minimum pressure. For filling with liquid ammonia, the data obtained from the pressure sensor can be observed, and the liquid ammonia can be pressurized in stages, with each stage filling the liquid ammonia to the target pressure.

[0061] Gas purging and filling process: First, keep all valves closed, open nitrogen pressure reducing valve 2, first solenoid valve 4, and fourth solenoid valve 9 to purge the pressure-bearing sealed container 11 with nitrogen, remove the air inside the pressure-bearing sealed container 11, avoid contact between hydrogen and oxygen, and ensure the safe use of hydrogen; the four-way valve of the air intake unit is always in the open state to connect multiple gas paths.

[0062] Maintain for 1-3 minutes, then close nitrogen pressure reducing valve 2 and open hydrogen pressure reducing valve 1 to purge nitrogen out of the pressure-bearing sealed container 11. Keep the fourth solenoid valve 9 open until the hydrogen leak alarm 7 sounds, confirming that the hydrogen has purged the nitrogen completely and that no excessive hydrogen has escaped. At this point, close the fourth solenoid valve 9 and continue filling the pressure-bearing sealed container 11 with hydrogen to increase the pressure inside the container and provide sufficient hydrogen for ammonia-hydrogen dissolution.

[0063] Step Two: The Pressurization and Filling Process of Liquid Ammonia

[0064] When the pressure inside the pressure-bearing sealed container 11 reaches 2 MPa (at this point, the hydrogen in the pressure-bearing sealed container 11 is considered to be in excess), close the first solenoid valve 4, open the liquid ammonia pressure reducing valve 15, connect the liquid ammonia bottle to the liquid ammonia pump 14, and start the liquid ammonia pump 14 to make the liquid ammonia pressure in the high-pressure oil pipe 16 reach 10 MPa. Open the second solenoid valve 6, and a portion of the liquid ammonia will be sprayed into the pressure-bearing sealed container 11 through the porous spray pipe 10; when the pressure inside the pressure-bearing sealed container 11 reaches 10 MPa, close the second solenoid valve 6, stop the liquid ammonia pump 14, and let it stand for 10-15 minutes;

[0065] Then, the liquid ammonia pump 14 is turned on to increase the pressure of the liquid ammonia in the high-pressure oil pipe 16 to 20 MPa. The second solenoid valve 6 is then opened. As the higher-pressure liquid ammonia is injected, the liquid in the pressure-bearing sealed container 11 flows, accelerating the dissolution of hydrogen. When the pressure in the pressure-bearing sealed container 11 reaches 20 MPa, the second solenoid valve 6 is closed, the liquid ammonia pump 14 is stopped, and the container is left to stand for 10-15 minutes.

[0066] Repeat the above operation, each time the liquid ammonia pump 14 is turned on, the pressure is increased by 10MPa until the pressure in the pressure-bearing sealed container reaches 50MPa; at this time, close the second solenoid valve 6, stop the liquid ammonia pump 14, close the liquid ammonia pressure reducing valve, and let it stand for more than 2 hours to allow the ammonia and hydrogen inside to fuse to form ammonia-hydrogen fused fuel.

[0067] Step 3: Injection of the mixed fuel and measurement of hydrogen solubility

[0068] Before fuel injector 24 injects fuel, observe and record the mass of high-precision mass scale 20 located at the bottom of non-pressure sealed container 19.

[0069] Open the third solenoid valve 8, and control the fuel injector 24 via computer 25 to inject the fused fuel in the pressure-bearing sealed container 11 into the non-pressure-bearing sealed container 19. The injection is completed after 100 injections.

[0070] Close the third solenoid valve 8 and open the pressure relief valve 13 to discharge the liquid ammonia in the pressure-bearing sealed container 11; after the pressure sensor 5 outputs that the pressure value in the pressure-bearing sealed container 11 has dropped to 1MPa, open the nitrogen pressure reducing valve 2 and the first solenoid valve 4 to purge the hydrogen in the pressure-bearing sealed container 11 with nitrogen; the ammonia and / or nitrogen discharged from the pressure relief valve 13 are absorbed in the ammonia post-treatment device 21.

[0071] After 100 injections, the mass of the weighing scale 20 is recorded to obtain the mass change of the non-pressurized sealed container 19, and the mass of liquid ammonia injected after 100 injections is obtained. The hydrogen concentration (mole fraction, unit is ppm) is obtained by measuring the hydrogen by the hydrogen sensor 18, and the hydrogen solubility ratio in the actual fused fuel (i.e. hydrogen solubility) is calculated.

[0072] The theoretical hydrogen solubility in the fused fuel was compared with the actual hydrogen solubility in the fused fuel to verify the impact of pressure fluctuations caused by the pressurization of the liquid ammonia pump, the lifting of the fuel injector needle valve, and the establishment of pressure at the nozzle on the actual hydrogen solubility of the fused fuel prepared based on the theoretical hydrogen solubility. Furthermore, if the theoretical hydrogen solubility and the actual hydrogen solubility in the fused fuel are inconsistent, the ratio of the fused fuel can be further modified based on the verification results to determine the minimum hydrogen content required by ammonia-hydrogen engines with different operating modes, thereby preparing a fused fuel with a hydrogen-ammonia ratio adapted to the corresponding ammonia-hydrogen engine.

[0073] This invention takes into account that pressure fluctuations during the lifting of the injector needle valve and the pressure build-up process at the nozzle can affect the actual solubility of the fused fuel sprayed by the injector. Therefore, it is necessary to verify the prepared fused fuel and consider its application. The purpose is to explore a strategy to support the application of ammonia-hydrogen fused fuel in engines.

[0074] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is merely for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in the embodiments can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A system for preparing a fusion fuel through ammonia fuel modification and upgrading, characterized in that, It includes a gas supply unit, an ammonia supply unit, an ammonia-hydrogen mixing unit, an ammonia-hydrogen aftertreatment unit, a fuel injector (24), and a fuel verification unit. The gas supply unit is used to provide hydrogen or purging gas; The ammonia supply unit is used to supply liquid ammonia; The ammonia-hydrogen mixing unit includes a pressure-sealed container (11) for mixing liquid ammonia from the ammonia supply unit with hydrogen from the gas supply unit in the pressure-sealed container (11) to form liquid ammonia-hydrogen fusion fuel; the inlet of the pressure-sealed container (11) is connected to the gas supply unit and the ammonia supply unit respectively; its outlet is connected to the ammonia-hydrogen after-treatment unit, the fuel injector (24) and the outside world respectively; The fuel injector (24) has its fuel inlet connected to the outlet of the ammonia-hydrogen mixing unit via a pipeline for injecting the prepared ammonia-hydrogen fused fuel; the fuel injector's return port is connected to the ammonia-hydrogen after-treatment unit. The ammonia-hydrogen aftertreatment unit includes an ammonia aftertreatment device (21) and a hydrogen recovery device (22). The inlet of the ammonia aftertreatment device (21) is connected to the outlet of the pressure-sealed container (11) and the return port of the fuel injector (24). The ammonia aftertreatment device (21) is used to chemically react the incoming ammonia- and / or hydrogen-containing mixed gas or liquid ammonia-hydrogen fusion fuel with the weak acid solution inside, absorb the ammonia, and send the remaining hydrogen-containing mixed gas into the hydrogen recovery device (22) through a pipeline. The hydrogen recovery device (22) uses physical adsorption and filtration to purify the gas from the ammonia aftertreatment device (21), separate and recover hydrogen. The fuel verification unit is used to receive and measure the fuel injected from the fuel injector (24) to verify its hydrogen content; compare the actual hydrogen content with the theoretical hydrogen content of the preset fusion fuel to verify the impact of pressure fluctuations caused during the application of fusion fuel on the actual value of hydrogen solubility, and then prepare corresponding ammonia-hydrogen fusion fuel for different ammonia-hydrogen engines.

2. The ammonia fuel upgrading and modification fusion fuel preparation system according to claim 1, characterized in that, The ammonia-hydrogen mixing unit also includes a pressure sensor (5) and a valve assembly; the pressure sensor (5) is located inside the pressure-bearing sealed container (11) and is used to monitor its internal pressure; the valve assembly is electrically connected to a computer (25) and is used to control the opening / closing of the corresponding valve assembly based on the feedback from the pressure sensor (5) and the control commands from the computer (25); The valve assembly includes a first solenoid valve (4), a third solenoid valve (8), a pressure limiting valve (12), and a pressure relief valve (13). The pressure relief valve (12) is installed on the pipeline between the pressure-bearing sealed container (11) and the hydrogen recovery device (22). It opens when the pressure inside the pressure-bearing sealed container (11) exceeds a preset safety threshold to safely release pressure. The pressure relief valve (13) is located on another pipeline between the pressure-bearing sealed container (11) and the ammonia post-treatment device (21), and is controlled by the computer (25) to open in order to discharge liquid ammonia; The first solenoid valve (4) is installed on the pipeline between the pressure-bearing sealed container (11) and the gas supply unit. It is controlled by the computer (25) to open, so that the hydrogen / purge gas of the gas inlet unit is introduced into the pressure-bearing sealed container (11). The third solenoid valve (8) is installed on the pipeline between the pressure-bearing sealed container (11) and the fuel injector (24) for feeding the fused fuel prepared in the pressure-bearing sealed container (11) into the fuel injector (24).

3. The ammonia fuel upgrading and modification fusion fuel preparation system according to claim 1, characterized in that, The valve assembly also includes a manual pressure relief valve (29) and a fourth solenoid valve (9); the manual pressure relief valve (29) connects the pressure-bearing sealed container (11) and the outdoor atmosphere / ammonia aftertreatment device (21) and is used to discharge the gas in the pressure-bearing sealed container (11) by exhaust; the fourth solenoid valve (9) connects the pressure-bearing sealed container (11) and the ammonia aftertreatment device (21) and is opened by computer control during the purging gas purging and hydrogen filling process.

4. The ammonia fuel upgrading and modification fusion fuel preparation system according to claim 1, characterized in that, The hydrogen recovery device (22) is equipped with a hydrogen molecular sieve for separating and purifying hydrogen from the gas after ammonia absorption.

5. The ammonia fuel upgrading and modification fusion fuel preparation system according to claim 1, characterized in that, The system also includes a hydrogen recovery circuit, which includes a gas pump (26) and a hydrogen pressure stabilizing tank (28). The inlet of the gas pump (26) is connected to the outlet of the hydrogen recovery device (22), and the outlet of the gas pump (26) is connected to the inlet of the hydrogen pressure stabilizing tank (28). The outlet of the hydrogen pressure stabilizing tank (28) is connected to the gas supply unit, so that the recovered hydrogen can be sent back to the pressure-bearing sealed container (11) for recycling.

6. The ammonia fuel upgrading and modification fusion fuel preparation system according to claim 5, characterized in that, The gas supply unit includes a hydrogen source and a nitrogen source, as well as a four-way valve (3); the first port and the second port of the four-way valve (3) are respectively connected to the hydrogen source and the nitrogen source, the third port is connected to the air inlet of the pressure-bearing sealed container (11), and the fourth port is connected to the hydrogen recovery circuit.

7. The ammonia fuel upgrading and modification fusion fuel preparation system according to claim 1, characterized in that, The ammonia supply unit includes a liquid ammonia pump (14) and a high-pressure oil pipe (16); the high-pressure oil pipe (16) is connected to the inlet of the pressure-bearing sealed container (11) through a second solenoid valve (6), and a multi-hole spray pipe (10) is connected inside the pressure-bearing sealed container (11) for spraying and atomizing the liquid ammonia from the high-pressure oil pipe (16).

8. The ammonia fuel upgrading and modification fusion fuel preparation system according to claim 1, characterized in that, The fuel verification unit includes a non-pressurized sealed container (19), inside which a hydrogen sensor (18) is installed to detect the hydrogen concentration in the injected fuel; a mass scale (20) is installed at the bottom of the non-pressurized sealed container (19) to weigh the total mass of the injected fuel; and the nozzle of the fuel injector (24) extends into the non-pressurized sealed container (19).

9. A fuel validation method for a fusion fuel preparation system based on ammonia fuel upgrading and modification according to any one of claims 1-8, comprising: Step 1: Pre-set the theoretical hydrogen solubility of the fusion fuel, and obtain the pressure and temperature conditions required to make the fusion fuel with the pre-set hydrogen-ammonia content ratio based on the ammonia-hydrogen dissolution test data; First, open the first solenoid valve (4) and the fourth solenoid valve (9), and use the purging gas of the gas supply unit to purge the pressure-bearing sealed container (11), and then use the hydrogen gas of the gas supply unit to purge the purging gas in the pressure-bearing sealed container (11); then fill the pressure-bearing sealed container (11) with hydrogen gas until the pressure in the pressure-bearing sealed container (11) reaches the preset initial pressure value, and then proceed to Step 2; Step 2: Close the first solenoid valve (4), and liquid ammonia from the ammonia supply unit enters the pressure-bearing sealed container (11) through the second solenoid valve (6) in the form of a spray at a preset initial pressure value; then, according to the target pressure for preparing fused fuel preset in Step 1, liquid ammonia is injected into the pressure-bearing sealed container in stages, and after each stage of injection, it is left to stand, so that the hydrogen in the pressure-bearing sealed container (11) dissolves in the liquid ammonia, and the pressure of the liquid ammonia injected in each stage increases incrementally; until the pressure in the container reaches the final target pressure, and then it is left to stand for a sufficient time to allow the ammonia and hydrogen to fully fuse and form ammonia-hydrogen fused fuel; Step 3: The ammonia-hydrogen fusion fuel formed after settling is quantitatively injected into the fuel verification unit through the fuel injector (24); the fuel verification unit is used to separate liquid ammonia and hydrogen, and the total mass of liquid ammonia and the concentration of hydrogen are measured to calculate the actual hydrogen solubility to verify its hydrogen content; the actual hydrogen solubility is compared with the theoretical hydrogen solubility set in Step 1 to verify the impact of pressure fluctuations caused by the prepared fusion fuel on the actual value of hydrogen solubility during the current application of the ammonia-hydrogen engine; if they are inconsistent, return to Step 1 to modify the theoretical hydrogen solubility, so as to prepare the corresponding ammonia-hydrogen fusion fuel according to the current working requirements of the ammonia-hydrogen engine.

10. The fuel verification method according to claim 9, characterized in that... Step two analyzes the specific process of pressurized fusion, including: Starting from the initial pressure, liquid ammonia is injected into the pressure-bearing sealed container (11) in multiple pressure steps. The operation of each pressure step includes: starting the liquid ammonia pump (14) to raise the liquid ammonia pressure to the target value, opening the second solenoid valve (6) to spray high-pressure liquid ammonia into the container, and closing the second solenoid valve (6) to stop the injection and let it stand after the pressure in the container reaches the target pressure of the pressure step; then proceeding to the next higher pressure step until the final target pressure is reached.

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