Combustion system and control method of internal combustion engine coupled with ammonia online reforming and hydrogen catalytic combustion

Abstract

The application discloses a combustion system and a control method of an internal combustion engine coupled with ammonia online reforming and hydrogen catalytic combustion, and the combustion system comprises a fuel supply and switching unit, an ammonia online catalytic reforming unit and an engine main body, the fuel supply and switching unit comprises a first fuel delivery pipeline and a second fuel delivery pipeline, the ammonia online catalytic reforming unit is connected with the output end of the first fuel delivery pipeline, and the engine main body is provided with a reforming product injector and an ignition chamber, wherein the reforming product injector is connected with the output end of the ammonia online catalytic reforming unit, and the ignition chamber is connected with the output end of the second fuel delivery pipeline. The technical scheme of the application can be compatible with various low-carbon fuels, realize efficient and stable combustion, and has a novel combustion system with energy self-sustaining and recycling capabilities, so as to promote the transformation and upgrading of the internal combustion engine to a green, efficient and intelligent direction.

Description

Technical Field

[0001] This invention belongs to the field of internal combustion engine power and new energy utilization technology, and particularly relates to an internal combustion engine combustion system and control method that couples online ammonia reforming and hydrogen catalytic combustion. Background Technology

[0002] Currently, the global energy system is undergoing a profound transformation from high-carbon to low-carbon, and then to zero-carbon. Internal combustion engines, as core power devices in transportation, construction machinery, power generation, and shipping, have long been highly dependent on fossil fuels, resulting in massive emissions of greenhouse gases and pollutants. Statistics show that carbon dioxide emissions from traditional gasoline and diesel engines account for more than 70% of total emissions in the transportation sector, along with emissions of particulate matter (PM) and nitrogen oxides (NOx), posing a serious threat to the environment and human health. Under the dual pressures of energy security and environmental protection, promoting the diversification, decarbonization, and even zero-carbonization of internal combustion engine fuels has become an inevitable trend in the industry's development.

[0003] In recent years, new alternative fuels such as methanol, ammonia, and hydrogen have been regarded as important technological paths to achieve carbon neutrality in the field of internal combustion engines due to their renewable, low-carbon, or zero-carbon characteristics. Among them, methanol fuel has a high oxygen content, a low carbon-to-hydrogen ratio, and good atomization and combustion characteristics, and has achieved initial commercial application in some countries and regions; ammonia fuel contains no carbon elements, does not produce carbon dioxide during combustion, and can be synthesized from hydrogen produced by renewable energy and then combined with nitrogen to achieve a zero-carbon cycle throughout its entire life cycle. At the same time, its low liquefaction pressure and convenient storage and transportation make it an ideal zero-carbon fuel for future heavy transportation and marine power; hydrogen, as the ultimate clean fuel, has only water as a combustion product, has extremely high flame propagation speed and reactivity, and can significantly improve combustion efficiency and thermal efficiency.

[0004] However, despite the promising environmental prospects of these fuels, their practical application still faces numerous technical bottlenecks. The significant differences in the physicochemical properties and combustion characteristics of different fuels result in poor engine adaptability. For example, methanol has a high latent heat of vaporization and low energy density, requiring optimized injection and ignition strategies; ammonia has a slow combustion rate, high ignition energy, and difficulty in ignition, easily leading to unstable combustion, decreased thermal efficiency, and increased emissions of unburned ammonia and nitrogen oxides; while hydrogen has excellent combustion performance, its flammability and explosiveness, high storage and transportation costs, and low volumetric energy density pose challenges for its large-scale safe application. Secondly, most existing internal combustion engines are designed for single fuel or fixed-ratio dual fuels, making it difficult to flexibly switch fuels based on regional fuel supply changes or price fluctuations, thus limiting the widespread adoption of low-carbon fuels.

[0005] To improve the combustion performance of ammonia fuel, researchers both domestically and internationally have proposed a technical route for hydrogen production through ammonia cracking to assist combustion. This involves decomposing a portion of ammonia into hydrogen and nitrogen through online reforming, utilizing the high reactivity of hydrogen to promote in-cylinder combustion. However, existing ammonia reforming technologies mostly rely on high-temperature electric heating or independent reaction devices, resulting in complex system structures, high start-up temperatures, and high energy consumption. Furthermore, they fail to effectively utilize engine exhaust waste heat, leading to low overall energy efficiency. In addition, hydrogen typically requires independent storage or external supply, increasing system complexity and safety risks, and failing to achieve cascaded energy utilization and internal system circulation.

[0006] Therefore, in response to the aforementioned profound technical contradictions, there is an urgent need for a new type of combustion system that can be compatible with a variety of low-carbon fuels and achieve efficient and stable combustion. Summary of the Invention

[0007] This invention aims to provide an internal combustion engine combustion system and control method that couples online ammonia reforming and hydrogen catalytic combustion. This novel combustion system is compatible with a variety of low-carbon fuels, achieves efficient and stable combustion, and has energy self-sufficiency and recovery capabilities, thereby promoting the transformation and upgrading of internal combustion engines towards green, efficient, and intelligent directions.

[0008] According to one aspect of the present invention, an internal combustion engine combustion system coupling ammonia online reforming and hydrogen catalytic combustion is provided, comprising a fuel supply and switching unit, an ammonia online catalytic reforming unit, and an engine body. The fuel supply and switching unit includes a first fuel delivery pipeline and a second fuel delivery pipeline. The first fuel delivery pipeline includes a liquid ammonia tank, a first flow meter, a first supply pump, and a first three-way control valve connected in sequence. The second port of the first three-way control valve serves as the output end of the first fuel delivery pipeline. The second fuel delivery pipeline includes a methanol tank, a second flow meter, a second supply pump, a second three-way control valve, a third three-way control valve, and a fourth three-way control valve connected in sequence. The second port of the fourth three-way control valve serves as the output end of the second fuel delivery pipeline. The third port of the second three-way control valve is connected to the second port of the fourth three-way control valve. The third port of the third three-way control valve is connected to the input end of the mixed fuel preparation device. The output end of the mixed fuel preparation device is connected to the second port of the fourth three-way control valve. The third port of the fourth three-way control valve is connected to the third port of the first three-way control valve, thereby controlling the fuel supply path and providing ammonia fuel, methanol fuel, or mixed fuel to the engine body. The online ammonia catalytic reforming unit includes a reformer, a first booster pump, a pressure stabilizing tank, and a hydrogen storage tank connected in sequence. The input end of the reformer is connected to the output end of the first fuel delivery pipeline. The output end of the pressure stabilizing tank is connected to the output end of the online ammonia catalytic reforming unit. The input end of the hydrogen storage tank is connected to the output end of the pressure stabilizing tank. The output end of the hydrogen storage tank is connected to the output end of the online ammonia catalytic reforming unit. The reformer is equipped with a hydrogen catalytic reaction layer to utilize the heat released from the catalytic combustion of some hydrogen to compensate for the endothermic reaction of ammonia decomposition. The engine body is equipped with a reforming product injector and an ignition chamber. The reforming product injector is connected to the output end of the online ammonia catalytic reforming unit via a second booster pump, and the ignition chamber is connected to the output end of the second fuel delivery pipeline.

[0009] According to some embodiments, the engine body is also provided with a main combustion chamber: The ignition chamber is equipped with a spark plug and an ignition chamber fuel injector, and the main combustion chamber is equipped with a high-pressure fuel injector. The high-pressure fuel injector and the ignition chamber fuel injector are respectively controlled by the engine electronic control unit. The high-pressure fuel injector and the ignition chamber fuel injector are respectively connected to the output end of the second fuel delivery pipeline; The ignition chamber fuel injector and the high-pressure fuel injector are both direct injection injectors, and the flame jet generated by the ignition chamber is used to ignite ammonia or a methanol / ammonia mixture containing hydrogen as a combustion aid.

[0010] According to some embodiments, the internal combustion engine combustion system further includes an ignition and control unit: The ignition and control unit is connected to the control terminals and / or data acquisition terminals of each flow meter, supply pump, and three-way control valve in the fuel supply and switching unit, thereby automatically switching the opening or closing of each port of each three-way control valve according to the fuel supply and operating conditions. The ignition and control unit controls the reforming product injector, the high-pressure fuel injector, and the ignition chamber fuel injector in the engine body through the engine electronic control unit, respectively, to achieve fuel ratio regulation, flow distribution, and combustion optimization control.

[0011] According to some embodiments, the reformer further includes: An insulation layer is installed on the outside of the reformer tank to prevent heat loss; An ammonia thermal decomposition layer is set in the middle of the reformer tank and contains a catalyst for the ammonia decomposition reaction. A heat-conducting structure is provided between the hydrogen catalytic reaction layer and the ammonia thermal decomposition layer, thereby efficiently transferring the heat released by hydrogen catalytic combustion to the ammonia decomposition region.

[0012] According to some embodiments, the reformer utilizes the exhaust waste heat from the engine main body as a heat source to decompose a portion of the ammonia fuel into hydrogen-containing reformed gas.

[0013] According to some embodiments, the output end of the hydrogen storage tank and the output end of the pressure stabilizing tank are connected to the input end of the reformer; Hydrogen enters the reformer to participate in the hydrogen catalytic combustion reaction, thereby utilizing the heat released from combustion to increase the exhaust temperature.

[0014] According to another aspect of the present invention, a control method for an internal combustion engine combustion system is provided, comprising: Determine the target operating mode based on the current fuel supply status and engine operating conditions; According to the target operating mode, the three-way control valve group of the fuel supply and switching unit is controlled by the ignition and control unit to control the fuel path and ratio, thereby realizing three operating modes; The operating modes include pure ammonia mode, pure methanol mode, and methanol / ammonia mixed mode.

[0015] According to some embodiments, determining the target operating mode based on the current fuel supply status and engine operating conditions includes: During cold start and idling, the system operates in pure methanol mode. Under low load conditions, select the methanol / ammonia mixed mode; Under medium load conditions, when the exhaust temperature meets the reformer start-up threshold, the system switches between methanol / ammonia mixed mode and pure ammonia mode. Under high load conditions, select either pure ammonia mode or methanol / ammonia mixed mode.

[0016] According to some embodiments, the control method further includes: During the initial cold start of the system, hydrogen is introduced into the hydrogen catalytic reaction layer inside the reformer using a hydrogen storage tank. The hydrogen reacts with oxygen in the exhaust gas to produce catalytic combustion and release heat, raising the internal temperature of the reformer to the temperature required for the ammonia decomposition reaction.

[0017] According to some embodiments, the control method further includes: When the internal hydrogen concentration of the reformer exceeds the limit, the exhaust temperature is abnormal, or the fuel pipeline pressure fluctuates, the system will be forced to switch to pure methanol mode and / or the fuel supply will be cut off.

[0018] The technical solutions provided by the embodiments of the present invention have the following beneficial effects: This invention fundamentally solves the problems of poor fuel adaptability, low ammonia combustion efficiency, and high hydrogen storage and transportation risks in existing low-carbon fuel internal combustion engines by constructing a complete system consisting of a fuel supply and switching unit, an online ammonia catalytic reforming unit, and an engine body.

[0019] By enabling the independent and coordinated operation of the first and second fuel delivery pipelines, along with a multi-stage three-way control valve and a mixed fuel preparation device, flexible switching between three operating modes—pure ammonia, pure methanol, and methanol / ammonia mixed fuel—is achieved. This allows the engine to automatically select the optimal energy strategy based on fuel supply conditions and operating conditions, significantly improving the equipment's environmental adaptability and operational economy.

[0020] Most importantly, this invention utilizes the waste heat from engine exhaust to drive an online ammonia catalytic reforming unit, converting a portion of the ammonia fuel into hydrogen-rich reformed gas in real time. This highly reactive hydrogen is introduced into the intake manifold via a reforming product injector to participate in combustion, effectively improving the inherent defects of slow combustion speed and difficult ignition of ammonia fuel, significantly increasing the in-cylinder combustion rate and thermal efficiency, while avoiding the safety hazards caused by high-pressure hydrogen storage.

[0021] In addition, the system ensures the stability of reformed gas supply by setting up a pressure stabilizing tank, and relies on the ignition chamber jet ignition technology to reliably ignite ammonia or ammonia / methanol mixture in the main combustion chamber using the high temperature and high speed jet generated by the ignition chamber, further ensuring combustion stability and efficiency under various fuel modes, and finally achieving an internal combustion engine combustion solution that integrates fuel flexibility, high thermal efficiency, low emissions and high safety.

[0022] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of an internal combustion engine combustion system that couples online ammonia reforming and hydrogen catalytic combustion, as an example embodiment of the present invention.

[0024] Figure 2 This is a schematic diagram illustrating the working principle of the reformer in an internal combustion engine combustion system that couples online ammonia reforming and hydrogen catalytic combustion, as an example embodiment of the present invention.

[0025] Figure 3 This is a flowchart illustrating the control method of an internal combustion engine combustion system coupled with online ammonia reforming and hydrogen catalytic combustion, as an example embodiment of the present invention.

[0026] Figure 4This is a schematic diagram of various operating modes in the control method of the internal combustion engine combustion system coupled with online ammonia reforming and hydrogen catalytic combustion in an exemplary embodiment of the present invention.

[0027] Figure 5 This is a schematic diagram of the operating condition strategy in the control method of the internal combustion engine combustion system coupled with online ammonia reforming and hydrogen catalytic combustion in an exemplary embodiment of the present invention. Detailed Implementation

[0028] To further understand the content of this invention, a detailed description of the invention is provided in conjunction with the accompanying drawings and embodiments. The invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the relevant invention and are not intended to limit the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0029] This embodiment proposes an internal combustion engine combustion system and control method that couples online ammonia reforming and hydrogen catalytic combustion. This novel combustion system is compatible with a variety of low-carbon fuels, achieves efficient and stable combustion, and has energy self-sufficiency and recovery capabilities, thereby promoting the transformation and upgrading of internal combustion engines towards green, efficient, and intelligent directions.

[0030] According to some embodiments, the internal combustion engine combustion system of the present invention can flexibly switch between pure ammonia, pure methanol, and methanol / ammonia mixed fuel modes. Utilizing ignition chamber jet ignition technology and combined with the synergistic design of online ammonia catalytic reforming for hydrogen production and waste heat recovery from hydrogen catalytic combustion, it achieves diversified fuel utilization, improved combustion performance, and optimized emission control. It has significant innovation, novelty, and practicality, providing a new technical approach for the engineering application of low / zero carbon fuel internal combustion engines.

[0031] like Figure 1 As shown, this embodiment proposes an internal combustion engine combustion system that couples online ammonia reforming and hydrogen catalytic combustion.

[0032] According to an example embodiment, the internal combustion engine combustion system includes a fuel supply and switching unit 100, an online ammonia catalytic reforming unit 200, and an engine body 300. The fuel supply and switching unit 100 includes a first fuel delivery pipeline and a second fuel delivery pipeline. The first fuel delivery pipeline includes a liquid ammonia tank 14, a first flow meter 12, a first supply pump 10, and a first three-way control valve 9 connected in sequence. The second port B of the first three-way control valve 9 serves as the output end of the first fuel delivery pipeline.

[0033] The second fuel delivery pipeline includes a methanol tank 16, a second flow meter 13, a second supply pump 11, a second three-way control valve 8, a third three-way control valve 7, and a fourth three-way control valve 6 connected in sequence. The second port B of the fourth three-way control valve 6 serves as the output end of the second fuel delivery pipeline. The third port C of the second three-way control valve 8 is connected to the second port B of the fourth three-way control valve 6, and the third port C of the third three-way control valve 7 is connected to the input end of the mixed fuel preparation device 15. The output end of the mixed fuel preparation device 15 is connected to the second port B of the fourth three-way control valve 6, and the third port C of the fourth three-way control valve 6 is connected to the third port C of the first three-way control valve 9, thereby controlling the fuel supply path and providing ammonia fuel, methanol fuel, or a mixed fuel to the engine body 300.

[0034] Furthermore, the ammonia online catalytic reforming unit 200 includes a reformer 5, a first booster pump 19, a pressure stabilizing tank 18, and a hydrogen storage tank 17 connected in sequence. The input end of the reformer 5 is connected to the output end of the first fuel delivery pipeline. The output end of the pressure stabilizing tank 18 is connected to the output end of the ammonia online catalytic reforming unit 200. The output end of the pressure stabilizing tank 18 is also connected to the input end of the hydrogen storage tank 17. The output end of the hydrogen storage tank 17 is connected to the output end of the ammonia online catalytic reforming unit 200. The reformer 5 has a hydrogen catalytic reaction layer inside, which is used to compensate for the endothermic reaction of ammonia decomposition by utilizing the heat released from the catalytic combustion of some hydrogen. As the core hydrogen production module of this system, the ammonia online catalytic reforming unit 200 adopts a series topology of "reaction-boosting-pressure stabilization" to realize the in-situ preparation and stable supply of highly active hydrogen-containing reformed gas from liquid ammonia feedstock.

[0035] According to some embodiments, the output end of the hydrogen storage tank 17 is connected to the output end of the ammonia online catalytic reforming unit 200, and the output end of the pressure stabilizing tank 18 is connected to the input end of the hydrogen storage tank 17, thereby storing a portion of the reformed gas for use during system startup or mode switching. The output ends of the hydrogen storage tank 17 and the pressure stabilizing tank 18 are connected to the input end of the reformer 5. A hydrogen catalytic combustion reaction zone is provided upstream of the reformer 5. Hydrogen enters the reformer 5 to participate in the hydrogen catalytic combustion reaction, thereby utilizing the heat released by combustion to increase the exhaust temperature. By adding a small amount of hydrogen to the exhaust gas, an exothermic reaction occurs with oxygen to increase the exhaust temperature, which can be achieved by increasing the exhaust temperature by 50–300K, improving the energy supply conditions for the reforming reaction. At the same time, catalytic combustion can stabilize the exhaust temperature field, avoid local overheating, and improve system durability and energy efficiency.

[0036] The topology of this embodiment enables the system to independently supply ammonia fuel to the engine and reformer 5 in pure ammonia mode by controlling the on / off state of each three-way valve. For example, it allows for a single-route supply of methanol in pure methanol mode, and in methanol / ammonia mixed mode, ammonia and methanol are premixed in the fuel preparation device 15 before being supplied to the engine. This provides solid hardware support for the engine to select the optimal combustion strategy under different operating conditions. It not only solves the problem of poor adaptability caused by the single fuel type in traditional internal combustion engines, but also achieves complementary fuel characteristics and improves combustion stability through the introduction of the fuel preparation device 15. This fundamentally solves the problems of poor fuel adaptability, low ammonia combustion efficiency, and high hydrogen storage and transportation risks in existing low-carbon fuel internal combustion engines.

[0037] According to some embodiments, the reformer 5 utilizes the exhaust waste heat of the engine body 300 as a heat source to decompose part of the ammonia fuel into hydrogen-containing reformed gas. Inside the ammonia online catalytic reforming unit 200, liquid ammonia first undergoes an endothermic decomposition reaction in the reformer 5 using the exhaust waste heat of the engine and internal catalytic action, transforming into a hydrogen-rich mixed gas; subsequently, the generated reformed gas is pressurized by the first booster pump 19 to overcome pipeline resistance and meet injection pressure requirements; finally, the pressurized gas enters the pressure stabilizing tank 18 for buffering and flow stabilization.

[0038] The pressure stabilizing tank 18 effectively eliminates airflow pressure oscillations caused by reforming reaction rate fluctuations or engine intake pulsations, ensuring a constant reforming gas flow rate and pressure output to the engine main body 300. This embodiment's structural design not only achieves efficient online cracking of ammonia fuel, avoiding the safety hazards of high-pressure hydrogen storage tanks, but also significantly improves the control precision of hydrogen combustion through physical pressure stabilization, providing a reliable gaseous fuel guarantee for the engine to achieve lean combustion and efficient clean operation.

[0039] Furthermore, the engine body 300 is provided with a reforming product injector 1 and an ignition chamber. The ignition chamber is provided with a spark plug 4 and an ignition chamber fuel injector 3. The reforming product injector 1 is connected to the output end of the ammonia online catalytic reforming unit 200 through a second booster pump 20, and the ignition chamber is connected to the output end of the second fuel delivery pipeline.

[0040] According to some embodiments, the engine body 300 is further provided with a main combustion chamber, which is equipped with a high-pressure fuel injector 2. The high-pressure fuel injector 2 and the ignition chamber fuel injector 3 are respectively controlled by the engine electronic control unit (ECU). The high-pressure fuel injector 2 and the ignition chamber fuel injector 3 are respectively connected to the output end of the second fuel delivery pipeline. The ignition chamber fuel injector 3 and the high-pressure fuel injector 2 are both direct injection injectors. The flame jet generated by the ignition chamber is used to ignite ammonia or a methanol / ammonia mixture containing hydrogen as a combustion aid. The engine body 300 adopts a dual-chamber structure layout with a separate main combustion chamber and ignition chamber, and integrates the reforming product injector 1, the ignition chamber fuel injector 3, and the main combustion chamber high-pressure fuel injector 2, forming a multi-level, high-efficiency combustion supply system.

[0041] Specifically, the input end of the reforming product injector 1 is connected to the output end of the ammonia online catalytic reforming unit 200, responsible for precisely injecting the highly reactive hydrogen-containing gas produced by reforming into the intake manifold or cylinder as a combustion aid. The ignition chamber is connected to the output end of the second fuel delivery pipeline and contains a spark plug 4 and an ignition chamber fuel injector 3. This injector is a direct injection type, controlled by the engine electronic control unit, and is used to precisely inject ammonia or mixed fuel into the ignition chamber. The main combustion chamber is also equipped with a high-pressure fuel injector 2 controlled by the ECU. This injector is also a direct injection type and is connected to the second fuel delivery pipeline, used to inject the main fuel into the main combustion chamber.

[0042] During operation, the fuel in the ignition chamber is ignited by spark plug 4, generating a high-temperature, high-speed flame jet. This jet passes through the nozzle and enters the main combustion chamber, reliably igniting the ammonia or methanol / ammonia mixture containing hydrogen as a combustion aid. This effectively overcomes the problems of high ignition energy and slow flame propagation associated with ammonia fuel. Combined with hydrogen combustion aid, it significantly improves the combustion rate and stability in the main combustion chamber, achieving efficient and clean lean combustion. This allows the system to flexibly respond to different fuel characteristics, unlocking the possibility of freely switching between ammonia, methanol, and their mixtures as flexible fuels.

[0043] Furthermore, the reformer 5 adopts a multi-layer coaxial structure. An insulation layer is installed on the outside of the reformer 5 tank to prevent heat loss. An ammonia thermal decomposition layer is installed in the middle of the reformer 5 tank, containing a catalyst for ammonia decomposition. The ammonia decomposition catalyst is preferably a ruthenium (Ru)-based catalyst or a nickel (Ni)-based catalyst to achieve a high-conversion ammonia cracking reaction. A hydrogen catalytic reaction layer is installed inside the reformer 5 tank to allow some hydrogen to react exothermically with oxygen in the exhaust gas, releasing heat to compensate for the endothermic reaction of ammonia. A heat-conducting structure is provided between the hydrogen catalytic reaction layer and the ammonia thermal decomposition layer, thereby efficiently transferring the heat released by hydrogen catalytic combustion to the ammonia decomposition zone. This cleverly achieves internal heat self-compensation, utilizing the combustion heat of the reaction product (hydrogen) to maintain the continuous high temperature required for ammonia decomposition. Thus, without consuming additional external energy, the high conversion rate and operational stability of the reformer 5 are ensured. Its working principle is described in [link to relevant documentation]. Figure 2 .

[0044] According to some embodiments, the reformer 5 includes an intake passage, a reaction chamber, a catalyst carrier, a heat exchange jacket, and a gas outlet. Engine exhaust enters the reformer 5 through the exhaust pipe, providing the heat required for the reaction; ammonia gas is introduced from the input end and undergoes ammonia thermal decomposition reaction in the reaction chamber under the action of a catalyst. The reformed gas produced is mainly composed of hydrogen and nitrogen. The reformed products flow through the outlet to the reformed product injector 1 in the engine body, where they are used as combustion-supporting gas to improve the in-cylinder combustion rate and combustion completeness.

[0045] According to some embodiments, the reformed gas produced by the reformer 5 is mainly fed directly into the engine intake manifold as an auxiliary combustion gas to improve combustion efficiency, and also enters the reformer 5 to participate in hydrogen catalytic combustion to increase exhaust temperature. However, to optimize system operational stability and meet different operating conditions, some of the reformed gas is also guided to the hydrogen storage tank 17. By storing a small amount of reformed gas, the hydrogen storage tank 17 can provide the necessary hydrogen during the initial start-up of the reformer 5 to accelerate its entry into working condition, and buffer and regulate the supply of reformed gas during mode switching. Through this structural design, the heat of the ammonia decomposition reaction and the hydrogen catalytic reaction complement each other, reducing the system's dependence on high-temperature exhaust gas, allowing the reformer 5 to start stably at a lower exhaust temperature (approximately 600K), and realizing the secondary utilization of exhaust gas energy.

[0046] According to some embodiments, the internal combustion engine combustion system further includes an ignition and control unit. This ignition and control unit is connected to the control terminals and / or data acquisition terminals of each flow meter, supply pump, and three-way control valve in the fuel supply and switching unit 100, thereby automatically switching the opening or closing of each port of the three-way control valve according to fuel supply and operating conditions. The ignition and control unit controls the reforming product injector 1, the high-pressure fuel injector 2, and the ignition chamber fuel injector 3 in the engine body 300 respectively through the engine electronic control unit, achieving fuel ratio regulation, flow distribution, and combustion optimization control.

[0047] The ignition and control unit in this embodiment achieves comprehensive closed-loop management from hardware execution to software strategy. It is physically deeply coupled with the fuel supply and switching unit 100, maintaining real-time communication with the control terminals and data acquisition terminals of flow meters, supply pumps, and three-way control valves on each pipeline. Based on this comprehensive data interaction, the control unit can accurately perceive the current fuel supply status and the actual operating conditions of the engine, and then automatically, quickly, and accurately execute the opening or closing commands of each three-way control valve port, achieving seamless switching between pure ammonia, pure methanol, or mixed fuel supply paths.

[0048] Furthermore, the ignition and control unit further refines and coordinates the combustion terminals through the engine electronic control unit (ECU). It independently controls the reformate injector 1, the main combustion chamber fuel high-pressure injector 2, and the ignition chamber fuel injector 3 within the engine body 300, thereby perfectly combining macroscopic fuel mode switching with the microscopic in-cylinder combustion process. This not only dynamically adjusts the ratio of hydrogen oxidizer to main fuel according to demand but also optimizes multi-point flow distribution.

[0049] According to some embodiments, the engine electronic control unit (ECU) serves as the core brain of the system, collecting key operating parameters from the engine and fuel system in real time and at high frequency, including but not limited to: fuel (ammonia, methanol) balance and supply flow, pressure of each fuel line, intake and exhaust temperatures, internal temperature and pressure of reformer 5, internal hydrogen concentration of reformer 5, engine speed, etc.

[0050] The ECU can dynamically implement fuel distribution and injection strategies, as well as coordinated control during the reforming process, based on real-time data and engine operating characteristics. This is achieved through precise control of the supply pumps for each fuel (ammonia, methanol), the opening of the three-way valve, and the injection timing, pulse width, and pressure of the injectors. This enables seamless switching and proportional adjustment between various fuel modes, such as pure ammonia, pure methanol, and methanol / ammonia blends, to optimize combustion efficiency, power output, and emissions performance.

[0051] Based on engine operating conditions and hydrogen demand, the system coordinates and adjusts the hydrogen distribution to reformer 5 and the flow rate of the ammonia fuel pump to ensure that reformer 5 operates at the optimal temperature and efficiently and on-demand produces hydrogen online. Simultaneously, it manages the distribution of reformer gas to hydrogen storage tank 17 to meet start-up and transient buffering needs. This deep hardware and software collaborative control strategy ensures that the engine maintains optimal air-fuel ratio and ignition timing under various complex operating conditions, ultimately achieving efficient combustion optimization and emission control in multi-fuel modes.

[0052] See Figure 3 This illustrates the control method for the combustion system of an internal combustion engine.

[0053] In S101, the target operating mode is determined based on the current fuel supply status and engine operating conditions.

[0054] According to some embodiments, the operation mode definition and logic determination program is first executed, which clearly defines three core operating conditions: pure ammonia mode, pure methanol mode, and methanol / ammonia mixed mode. For each mode, a precise on or off state matrix of each three-way control valve is preset, thereby constructing the basic logic architecture for fuel path switching.

[0055] In S103, according to the target operating mode, the three-way control valve group of the fuel supply and switching unit is controlled by the ignition and control unit to control the fuel path and ratio, thereby realizing three operating modes.

[0056] According to some embodiments, the current fuel supply status and engine operating parameters are collected in real time, compared and analyzed with the preset operating strategy, and the preset operating strategy is automatically executed to automatically match the optimal operating mode based on the current fuel supply and operating conditions. According to the judgment result, instructions are sent to each actuator to automatically execute the corresponding valve action to complete the physical switching of the fuel supply path, ensuring that the internal combustion engine can flexibly adjust to the optimal combustion state according to the actual energy conditions.

[0057] Further, see Figure 4 The figure shows three operating modes of the system. The ignition and control unit controls the fuel supply and switching unit to control the on or off state of each three-way control valve.

[0058] According to some embodiments, in pure ammonia mode, the ammonia passage valve is opened, connecting the BC path of the fourth three-way control valve 6 and the ABC path of the first three-way control valve 9, allowing liquid ammonia to enter the engine's main combustion chamber, ignition chamber, and reformer 5, respectively. High-pressure direct ammonia injection can increase the fuel volumetric injection rate, and the high-energy jet generated in the ignition chamber ensures stable ignition of the liquid ammonia spray. Hydrogen generated from ammonia reforming is introduced into the intake manifold via pipeline and then enters the combustion chamber during the engine's intake stroke, where it burns together with the ammonia, further improving the problems of slow combustion speed and difficult ignition.

[0059] In pure methanol mode, only the methanol passage is open, and the BC circuit of the second three-way control valve 8 is connected. Methanol is burned through ignition chamber injection and direct injection into the main combustion chamber. High-pressure direct injection of methanol can increase the volumetric injection volume of fuel, and the high latent heat of vaporization can reduce the in-cylinder temperature, thereby suppressing NOx emissions. The high-energy jet generated in the ignition chamber can ensure stable ignition and efficient combustion of the methanol spray.

[0060] In methanol / ammonia mixing mode, the valves for ammonia, methanol, and the mixing passage are opened simultaneously. The AC path of the fourth three-way control valve 6, the ABC path of the third three-way control valve 7, the AB path of the second three-way control valve 8, and the ABC path of the first three-way control valve 9 are all connected. Liquid ammonia and methanol are thoroughly mixed in the mixer to form a homogeneous fuel mixture, which is then directly injected into the combustion chamber and ignition chamber. The high reactivity of methanol promotes stable ignition and rapid, efficient combustion of the ammonia fuel. Part of the ammonia enters the reformer 5 to produce hydrogen, which is then injected through the intake manifold to participate in combustion, further improving the completeness of combustion of the fuel mixture and reducing emissions of unburned ammonia, methanol, and N2O.

[0061] Furthermore, such as Figure 5 The preset operating conditions strategy includes: operating in pure methanol mode under cold start and idling conditions; switching to methanol / ammonia mixed mode under low load conditions; switching between methanol / ammonia mixed mode and pure ammonia mode under medium load conditions when the exhaust temperature meets the reformer 5 start threshold; and using pure ammonia mode or methanol / ammonia mixed mode under high load conditions.

[0062] Specifically, during cold starts and idling, the engine cylinder and exhaust temperatures are low, resulting in insufficient combustion activity of ammonia fuel and the inability of reformer 5 to effectively produce hydrogen. In this situation, the system prioritizes pure methanol mode, combined with hydrogen injection from the hydrogen storage tank 17. Compared to ammonia fuel, methanol has better combustion activity and ignition performance at low temperatures, allowing for rapid ignition and stable operation, which quickly raises the exhaust temperature, creating conditions for the subsequent start-up of the ammonia catalytic reformer 5 and avoiding the difficulties of cold starts with ammonia fuel.

[0063] According to some embodiments, during the initial cold start phase of the system, hydrogen is introduced into the hydrogen catalytic reaction layer inside the reformer 5 via the hydrogen storage tank 17. This hydrogen reacts with oxygen in the exhaust gas through catalytic combustion, releasing heat and rapidly raising the internal temperature of the reformer 5 to the temperature required for the ammonia decomposition reaction. During the cold start phase, since the engine exhaust temperature is still low and insufficient to directly drive the endothermic decomposition reaction of ammonia, the system uses the external hydrogen storage tank 17 as a temporary supply device to directionally introduce hydrogen into the hydrogen catalytic reaction layer inside the reformer 5 via control logic. The hydrogen entering the reaction layer reacts rapidly with residual oxygen in the exhaust gas through catalytic combustion under the action of the catalyst. This exothermic process releases a large amount of heat energy in a very short time, which is efficiently transferred to the ammonia thermal decomposition layer via the aforementioned heat-conducting structure. This "self-heating" mechanism can overcome the thermal inertia during cold starts and quickly raise the internal temperature of the reformer 5 to the active temperature range required for the ammonia decomposition reaction. This significantly shortens the preheating waiting time of the reformer 5, ensuring that the engine can quickly use ammonia fuel or reformed hydrogen for combustion after a cold start, and significantly improves the dynamic response performance and operating efficiency of the system during the cold start phase.

[0064] Under low-load conditions, the exhaust temperature is relatively low, and the combustion activity of ammonia fuel remains insufficient. The system switches to a methanol / ammonia mixed mode. The good combustion characteristics of methanol improve the combustion stability of ammonia and reduce unburned materials. Meanwhile, although the hydrogen production efficiency of reformer 5 is limited, it can still produce a small amount of hydrogen to aid combustion, improving the combustion activity of the mixed fuel and ensuring stable operation under low load conditions.

[0065] Under medium load conditions, the exhaust temperature is sufficient for stable operation of reformer 5, resulting in high hydrogen production efficiency. The system can flexibly select between a methanol / ammonia mixed mode or a pure ammonia mode. The mixed mode balances combustion efficiency and emissions; the pure ammonia mode maximizes the use of zero-carbon ammonia fuel, achieving efficient and stable zero-carbon operation through sufficient hydrogen combustion assistance. The choice depends on fuel supply, economics, and emission requirements.

[0066] Under high-load conditions, the exhaust temperature is high, and the hydrogen production efficiency of reformer 5 is optimal, with sufficient hydrogen for combustion. The system preferentially selects the pure ammonia mode. The pure ammonia mode can achieve the best efficiency and stability, achieving zero carbon emissions. If further optimization of NOx emissions is required, or if methanol supply is economically advantageous, it can be switched to the methanol / ammonia mixed mode, utilizing the high volumetric latent heat of vaporization of methanol to reduce the in-cylinder combustion temperature, achieving a balance between combustion efficiency and emissions.

[0067] Preferably, when fuel supply is sufficient, it is recommended to fill the tank with both types of fuel. When fuel supply is limited, a single fuel (methanol or ammonia) can be selected for refueling depending on the actual situation. The engine can flexibly adapt and optimize its operation under each fuel mode. For example, when both types of fuel are sufficient in the fuel tank, the system can adjust the switching and ratio of the three modes in real time according to engine load, speed, and fuel availability to achieve automatic and seamless fuel switching.

[0068] According to some embodiments, the control method further includes: when the internal hydrogen concentration of the reformer 5 exceeds the limit, the exhaust temperature is abnormal, or the fuel line pressure fluctuates, forcibly switching to pure methanol mode and / or cutting off the fuel supply. Optionally, a comprehensive fault diagnosis and safety protection mechanism built into the ECU can be used to continuously monitor all the above-mentioned key parameters. For example, when the exhaust temperature rises or falls abnormally, the internal hydrogen concentration of the reformer 5 exceeds the safe range, the fuel line pressure fluctuates abnormally, or abnormal combustion phenomena such as knocking or misfire are detected, the ECU will immediately activate a preset safety strategy to reduce the engine speed to avoid further damage, and at the same time issue a warning signal to alert the operator. These synergistic optimization control and multi-level safety protection functions jointly ensure that the flexible fuel internal combustion engine system maintains an efficient, stable, and safe operating state in complex and ever-changing operating environments, and maximizes its low-carbon and environmentally friendly advantages.

[0069] The internal combustion engine combustion system and control method coupled with online ammonia reforming and hydrogen catalytic combustion described in this invention cleverly integrates online ammonia reforming for hydrogen production, hydrogen catalytic combustion, and ignition chamber jet ignition technology into the internal combustion engine system, constructing a highly efficient and fuel-adaptive internal combustion system. By adding the ignition and control unit, the system possesses the ability to intelligently and seamlessly switch between pure ammonia, pure methanol, and methanol / ammonia mixed modes based on engine load, speed, and fuel supply conditions. This high degree of flexibility ensures that the engine can select the optimal fuel strategy under various operating scenarios. For example, during cold starts, the volatility of methanol ensures reliable starting, while during high-load periods, the zero-carbon characteristics of ammonia achieve clean power, significantly improving fuel compatibility and operating efficiency.

[0070] By utilizing the high-temperature exhaust gas from the engine to drive the reformer 5, ammonia is decomposed into hydrogen-rich reformed gas in real time, achieving effective waste heat recovery. Furthermore, innovatively, some hydrogen reacts with oxygen in the exhaust gas within the reformer 5 to release heat. A heat-conducting structure maintains the endothermic environment required for the ammonia decomposition reaction, forming a highly efficient internal self-circulation of exhaust gas energy. The generated hydrogen, acting as a highly reactive combustion aid, is introduced into the combustion chamber, significantly accelerating the combustion rate of ammonia or methanol / ammonia mixed fuels, greatly improving combustion efficiency, while effectively avoiding the complexity and safety hazards of traditional high-pressure hydrogen storage.

[0071] By employing advanced ignition chamber jet ignition technology, a small amount of fuel is ignited in an independent ignition chamber by spark plug 4 to generate a high-temperature, high-speed flame jet, which is then injected into the main combustion chamber. This technology can efficiently and reliably ignite the gas-fuel mixture, solving the problem of difficult ignition of hydrogen-containing ammonia. Even in pure methanol mode without hydrogen, the high-energy flame jet can ensure rapid and stable ignition of methanol, making it a key support for achieving stable combustion of multiple fuels under all operating conditions.

[0072] In summary, this invention significantly improves the system's thermal efficiency and combustion stability by enabling flexible fuel utilization, online hydrogen production for combustion assistance, and deep reuse of waste gas energy, supplemented by efficient ignition technology. Its compact structure, high safety, strong fuel compatibility, and significant energy-saving and emission-reduction effects make it highly suitable for various application scenarios with strict emission and efficiency requirements, such as ships, heavy vehicles, and distributed energy sources.

[0073] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An internal combustion engine combustion system coupling ammonia online reforming and hydrogen catalytic combustion, characterized in that, The internal combustion engine combustion system includes a fuel supply and switching unit, an online ammonia catalytic reforming unit, and the engine body. The fuel supply and switching unit includes a first fuel delivery pipeline and a second fuel delivery pipeline; The first fuel delivery pipeline includes a liquid ammonia tank, a first flow meter, a first supply pump, and a first three-way control valve connected in sequence. The second port of the first three-way control valve serves as the output end of the first fuel delivery pipeline. The second fuel delivery pipeline includes a methanol tank, a second flow meter, a second supply pump, a second three-way control valve, a third three-way control valve, and a fourth three-way control valve connected in sequence. The second port of the fourth three-way control valve serves as the output end of the second fuel delivery pipeline. The third port of the second three-way control valve is connected to the second port of the fourth three-way control valve. The third port of the third three-way control valve is connected to the input end of the mixed fuel preparation device. The output end of the mixed fuel preparation device is connected to the second port of the fourth three-way control valve. The third port of the fourth three-way control valve is connected to the third port of the first three-way control valve, thereby controlling the fuel supply path and providing ammonia fuel, methanol fuel, or mixed fuel to the engine body. The online ammonia catalytic reforming unit includes a reformer, a first booster pump, a pressure stabilizing tank, and a hydrogen storage tank connected in sequence. The input end of the reformer is connected to the output end of the first fuel delivery pipeline. The output end of the pressure stabilizing tank is connected to the output end of the online ammonia catalytic reforming unit. The input end of the hydrogen storage tank is connected to the output end of the pressure stabilizing tank. The output end of the hydrogen storage tank is connected to the output end of the online ammonia catalytic reforming unit. The reformer is equipped with a hydrogen catalytic reaction layer to utilize the heat released from the catalytic combustion of some hydrogen to compensate for the endothermic reaction of ammonia decomposition. The engine body is equipped with a reforming product injector and an ignition chamber. The reforming product injector is connected to the output end of the online ammonia catalytic reforming unit via a second booster pump, and the ignition chamber is connected to the output end of the second fuel delivery pipeline.

2. The internal combustion engine combustion system according to claim 1, characterized in that, The engine body is also equipped with a main combustion chamber: The ignition chamber is equipped with a spark plug and an ignition chamber fuel injector, and the main combustion chamber is equipped with a high-pressure fuel injector. The high-pressure fuel injector and the ignition chamber fuel injector are respectively controlled by the engine electronic control unit. The high-pressure fuel injector and the ignition chamber fuel injector are respectively connected to the output end of the second fuel delivery pipeline; The ignition chamber fuel injector and the high-pressure fuel injector are both direct injection injectors, and the flame jet generated by the ignition chamber is used to ignite ammonia or a methanol / ammonia mixture containing hydrogen as a combustion aid.

3. The internal combustion engine combustion system according to claim 2, characterized in that, The internal combustion engine combustion system also includes an ignition and control unit: The ignition and control unit is connected to the control terminals and / or data acquisition terminals of each flow meter, supply pump, and three-way control valve in the fuel supply and switching unit, thereby automatically switching the opening or closing of each port of each three-way control valve according to the fuel supply and operating conditions. The ignition and control unit controls the reforming product injector, the high-pressure fuel injector, and the ignition chamber fuel injector in the engine body through the engine electronic control unit, respectively, to achieve fuel ratio regulation, flow distribution, and combustion optimization control.

4. The internal combustion engine combustion system according to claim 1, characterized in that, The reformer also includes: An insulation layer is installed on the outside of the reformer tank to prevent heat loss; An ammonia thermal decomposition layer is set in the middle of the reformer tank and contains a catalyst for the ammonia decomposition reaction. A heat-conducting structure is provided between the hydrogen catalytic reaction layer and the ammonia thermal decomposition layer, thereby efficiently transferring the heat released by hydrogen catalytic combustion to the ammonia decomposition region.

5. The internal combustion engine combustion system according to claim 1, characterized in that, The reformer utilizes the waste heat from the engine's main exhaust as a heat source to decompose a portion of the ammonia fuel into hydrogen-containing reformed gas.

6. The internal combustion engine combustion system according to claim 1, characterized in that, The output end of the hydrogen storage tank and the output end of the pressure stabilizing tank are connected to the input end of the reformer; Hydrogen enters the reformer to participate in the hydrogen catalytic combustion reaction, thereby utilizing the heat released from combustion to increase the exhaust temperature.

7. A control method for an internal combustion engine combustion system applied to the internal combustion engine combustion system according to any one of claims 1 to 6, characterized in that, include: Determine the target operating mode based on the current fuel supply status and engine operating conditions; According to the target operating mode, the three-way control valve group of the fuel supply and switching unit is controlled by the ignition and control unit to control the fuel path and ratio, thereby realizing three operating modes; The operating modes include pure ammonia mode, pure methanol mode, and methanol / ammonia mixed mode.

8. The control method according to claim 7, characterized in that, The process of determining the target operating mode based on the current fuel supply status and engine operating conditions includes: During cold start and idling, the system operates in pure methanol mode. Under low load conditions, select the methanol / ammonia mixed mode; Under medium load conditions, when the exhaust temperature meets the reformer start-up threshold, the system switches between methanol / ammonia mixed mode and pure ammonia mode. Under high load conditions, select either pure ammonia mode or methanol / ammonia mixed mode.

9. The control method according to claim 7, characterized in that, Also includes: During the initial cold start of the system, hydrogen is introduced into the hydrogen catalytic reaction layer inside the reformer using a hydrogen storage tank. The hydrogen reacts with oxygen in the exhaust gas to produce catalytic combustion and release heat, raising the internal temperature of the reformer to the temperature required for the ammonia decomposition reaction.

10. The control method according to claim 7, characterized in that, Also includes: When the internal hydrogen concentration of the reformer exceeds the limit, the exhaust temperature is abnormal, or the fuel pipeline pressure fluctuates, the system will be forced to switch to pure methanol mode and / or the fuel supply will be cut off.

Images