Ammonia internal combustion engine system and control method thereof

Abstract

This application relates to an ammonia internal combustion engine system and its control method, belonging to the field of internal combustion engines. The ammonia internal combustion engine system includes an ammonia supply device, an ammonia decomposition device, an engine block, and an ignition device. The ammonia supply device includes an ammonia injector for supplying ammonia. The ammonia decomposition device includes a catalyst for decomposing ammonia into nitrogen and hydrogen. The engine block includes a main combustion chamber. The ignition device is partially located within the main combustion chamber. The control method for the ammonia internal combustion engine includes controlling the total ammonia flow rate to 20–23 L / min, simultaneously controlling the ammonia decomposition rate in the ammonia decomposition device to 50–60%, and controlling the equivalence ratio to 1.05–1.23. This control process prioritizes power characteristics while also considering good burnout and emission characteristics. It not only provides a reference for the design and application of ammonia internal combustion engines but also represents a practical control method for ammonia internal combustion engines.

Description

Technical Field

[0001] This application relates to an ammonia internal combustion engine system and its control method, belonging to the field of internal combustion engines. Background Technology

[0002] Ammonia is an excellent carrier for hydrogen energy. An ammonia molecule consists of one nitrogen atom and three hydrogen atoms, with hydrogen atoms accounting for 17.6% of the molecule's mass. As the molecular structure shows, ammonia itself does not contain carbon atoms. Therefore, ammonia does not produce carbon dioxide during combustion; its complete combustion produces clean water and nitrogen, eliminating carbon dioxide emissions and not contributing to the greenhouse effect. The main challenge of using ammonia as an internal combustion engine fuel is its poor ignition and combustion performance. This is mainly manifested in its high ignition energy, slow flame propagation speed, and narrow flammability limit. Therefore, the combustion effect of ammonia fuel directly applied to internal combustion engines is less than satisfactory.

[0003] To improve the ignition and combustion of ammonia in internal combustion engines, researchers have proposed the following solutions: First, a dual-fuel system, mixing ammonia with gasoline or other hydrocarbon fuels; second, fuel additives, using hydrogen as a fuel additive. For the first approach, in spark-ignition internal combustion engines, the main hydrocarbon fuels used in ammonia and hydrocarbon dual-fuel systems are generally petroleum, methane, or other carbon-containing fuels, which undoubtedly produce byproducts such as carbon dioxide, carbon monoxide, and soot, thus subject to relevant carbon emission regulations. For the second approach, using the carbon-free fuel additive hydrogen to improve the ignition and combustion performance of ammonia in spark-ignition internal combustion engines is one of the most effective methods. This involves using a catalytic decomposition device to decompose a portion of the ammonia into hydrogen and nitrogen, resulting in a partially decomposed ammonia gas with good ignition and combustion characteristics. However, adding hydrogen as an additive requires new gas storage devices and ventilation pipelines, increasing equipment volume, posing safety risks to hydrogen storage, and requiring precise control of the hydrogen-to-ammonia supply ratio, which is challenging. Current research in this area is limited.

[0004] Based on the aforementioned pain points in the application of ammonia in internal combustion engines, researchers have proposed a new approach: installing an ammonia decomposition device before the ammonia enters the cylinder to partially decompose the ammonia into a partially decomposed ammonia, hydrogen, and nitrogen gas before it enters the cylinder for combustion. The low ignition energy, fast flame propagation speed, and wide flammability limit of hydrogen complement those of ammonia, thereby improving the ignition and combustion performance of ammonia and achieving good combustion performance of ammonia fuel in the internal combustion engine, ultimately achieving carbon-free operation of the internal combustion engine.

[0005] In existing technologies, Sawyer et al. decomposed ammonia into hydrogen and nitrogen using a decomposer made of stainless steel, loosely filled with a catalyst. The entire decomposer was electrically heated by a heater, and they found that approximately 25% of the ammonia was decomposed. Ryu et al. used exhaust heat to provide heat for the ammonia decomposer. After decomposition by the catalyst, ammonia was converted into a partially decomposed gas of ammonia, hydrogen, and nitrogen, which was then mixed evenly with air and gasoline before entering the internal combustion engine for combustion. Compared to an undecomposed ammonia-gasoline internal combustion engine, the decomposed ammonia-gasoline internal combustion engine had an average power increase of 0.2 kW, reduced nitrogen oxide emissions by 25 g / kW·h, reduced ammonia emissions by 2.5 g / kW·h, and reduced carbon monoxide emissions by 8 g / kW·h. Frigo et al. developed a decomposer suitable for ammonia internal combustion engines. The catalyst in the decomposer was a ruthenium-based catalyst. Experiments showed that at an engine speed of 3000 rpm, the partially decomposed ammonia gas had a similar thermal efficiency to that of a gasoline internal combustion engine, both around 28%. Ezzat et al. determined the thermodynamic advantages of partial ammonia decomposition in ammonia internal combustion engines through their research. Their study showed that as the mass fraction of ammonia in the partially decomposed ammonia gas increases, the output power of the internal combustion engine increases, but the energy and energy utilization rate of the entire system decrease.

[0006] Therefore, the aforementioned prior art disclosures indicate that ammonia fuel has the potential to be a carbon-free fuel for spark-ignition internal combustion engines. However, the narrow combustibility limit, low flame propagation speed, and high ignition energy of ammonia are scientific problems that urgently need to be solved. To address these issues, partially decomposing ammonia into hydrogen and nitrogen before it enters the spark-ignition internal combustion engine is a highly innovative and effective method.

[0007] However, this method is still in the theoretical stage and has not yet entered the practical application stage. Therefore, there is relatively little research on it. Implementation requires redesigning the internal combustion engine system, including a suitable intake system, a stable and effective ammonia decomposition device, and an exhaust gas treatment device. For example, in existing technologies, there is very little research on the actual impact of ammonia decomposition rate on internal combustion engine combustion. While the ammonia decomposition rate also has a significant impact on internal combustion engine emissions, existing technologies lack in-depth research on the impact of ammonia decomposition rate on the emissions of spark-ignition internal combustion engines.

[0008] Furthermore, in existing research on ammonia spark-ignition internal combustion engines, the total ammonia flow rate is often neglected; studies only use a single flow rate, ignoring the impact of different total ammonia flow rates on the engine. Finally, the stoichiometry ratio is equally important for internal combustion engines, reflecting the ratio of fuel to air. Different stoichiometry ratios result in different combustion and emission characteristics of partially decomposed ammonia in internal combustion engines, yet there is a lack of research on the impact of stoichiometry ratios on partially decomposed ammonia internal combustion engines in existing technologies.

[0009] Based on the problems existing in the above-mentioned technologies, there is an urgent need for a method that can be applied to ammonia internal combustion engines by systematically studying the effects of ammonia decomposition rate, total ammonia flow rate, and equivalence ratio on the combustion and emission characteristics of spark-ignition internal combustion engines. Summary of the Invention

[0010] To address the aforementioned issues, an ammonia internal combustion engine system and its control method are provided. This control method ensures good power characteristics of the ammonia internal combustion engine, such as speed, torque, power, and thermal effect, as well as good burnout characteristics, such as exhaust ammonia concentration, combustion efficiency, and fuel equivalence ratio. Furthermore, it considers good emission characteristics of nitric oxide, nitrogen dioxide, and nitrous oxide. This is a control process for an ammonia internal combustion engine that prioritizes power characteristics while also taking into account burnout and emission characteristics, providing an important reference for the practical design and application of ammonia internal combustion engines.

[0011] According to one aspect of this application, an ammonia internal combustion engine system is provided, the ammonia internal combustion engine system including a fuel supply module and an internal combustion engine module, the internal combustion engine module including an internal combustion engine body, the internal combustion engine body being a dual spark plug ignition type internal combustion engine, the fuel supply module being connected to the intake valve of the internal combustion engine body, the fuel supply module being used to supply the required fuel gas to the internal combustion engine module, and the ammonia decomposer being provided with a catalyst;

[0012] The fuel supply module includes an ammonia cylinder, a first flow meter, and an ammonia decomposer. The ammonia cylinder is connected to the first flow meter, and the other end of the first flow meter is connected to the ammonia decomposer. A gas pressure reducing valve is provided between the first flow meter and the ammonia decomposer. The opposite end of the first flow meter of the ammonia decomposer is connected to the intake valve of the internal combustion engine body.

[0013] Optionally, a second flow meter is provided between the ammonia decomposer and the inlet valve.

[0014] Optionally, the catalyst may include one or more of vanadium, ruthenium, rhodium, nickel, or platinum.

[0015] Optionally, the ammonia internal combustion engine system may also include a turbocharger.

[0016] Optionally, the ammonia internal combustion engine system further includes an exhaust gas recirculator, which is used to recover the discharged exhaust gas and provide heat to the ammonia decomposer.

[0017] According to another aspect of this application, a control method for any of the above-mentioned ammonia internal combustion engine systems is provided, the control method comprising:

[0018] 1) Ammonia supply and decomposition: Control the ammonia gas in the ammonia cylinder to enter the ammonia decomposer and undergo catalytic decomposition into ammonia and hydrogen;

[0019] 2) Intake: Open the intake valve of the internal combustion engine body, close the exhaust valve of the internal combustion engine body, and the gas in the ammonia decomposer enters the internal combustion engine body;

[0020] 3) Ignition: The ignition device ignites the ignition.

[0021] 4) Exhaust: Controls the opening of the exhaust valve of the internal combustion engine body and the closing of the intake valve of the internal combustion engine body.

[0022] Optionally, the total flow rate of ammonia provided by the ammonia cylinder is controlled to be 20~23L / min, the decomposition rate of ammonia in the ammonia decomposer is controlled to be 50~60%, and the equivalence ratio is controlled to be 1.05~1.23.

[0023] Optionally, the total flow rate of ammonia provided by the ammonia cylinder is controlled to be 20~22.5L / min, the decomposition rate of ammonia in the ammonia decomposer is controlled to be 50~55%, and the equivalence ratio is controlled to be 1.10~1.12.

[0024] Optionally, the total flow rate of ammonia provided by the ammonia cylinder is controlled to be 22.5 L / min, the decomposition rate of ammonia in the ammonia decomposer is controlled to be 50%, and the equivalent ratio is controlled to be 1.12.

[0025] The beneficial effects of this application include, but are not limited to:

[0026] 1. The control process of the ammonia internal combustion engine system according to this application can achieve excellent power characteristics such as speed, torque, power and thermal efficiency, while maintaining excellent ammonia burnout rate, including ammonia concentration, ammonia combustion efficiency, exhaust gas temperature and fuel equivalence ratio, and can also take into account good emission characteristics, resulting in low concentrations of nitric oxide, nitrogen dioxide and nitrous oxide in the emissions.

[0027] 2. Based on the control process of the ammonia internal combustion engine system of this application, the influence of ammonia decomposition rate, total ammonia flow rate and equivalence ratio on the combustion characteristics and emission characteristics of spark ignition internal combustion engines, which are not addressed in the prior art, is systematically studied. This study has important reference significance for the design and implementation of ammonia internal combustion engines.

[0028] 3. Based on the control technology of the ammonia internal combustion engine system in this application, and by studying aspects not yet addressed in existing technologies, a control method for ammonia internal combustion engines that integrates power characteristics, ammonia burnout rate, and emission characteristics has been obtained. This method has good practicality and economic value. The control conditions involved in the scheme include three equally important control parameters: ammonia decomposition rate, total ammonia flow rate, and equivalence ratio. Furthermore, by comprehensively considering power characteristics, ammonia burnout rate, and emission characteristics, with power characteristics as the primary factor and ammonia burnout rate and emission characteristics as secondary factors, a highly adaptable control method for ammonia internal combustion engines has been obtained. This promotes the development and application of ammonia internal combustion engines and provides guidance for the design and practice of ammonia internal combustion engines. Attached Figure Description

[0029] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0030] Figure 1 This is a schematic diagram of the structure of the ammonia internal combustion engine test platform involved in the embodiments of this application;

[0031] Figure 2 This is a schematic diagram showing the effect of ammonia decomposition rate on the speed and torque of an internal combustion engine in Experimental Example 1 of this application.

[0032] Figure 3 This is a schematic diagram showing the effect of ammonia decomposition rate on internal combustion engine power in Experimental Example 1 of this application.

[0033] Figure 4 This is a schematic diagram showing the effect of ammonia decomposition rate on the thermal efficiency of an internal combustion engine in Experimental Example 1 of this application.

[0034] Figure 5 This is a schematic diagram showing the effect of ammonia decomposition rate on ammonia emissions (left) and ammonia burnout rate (right) in the exhaust gas involved in Experiment Example 1 of this application.

[0035] Figure 6 This is a schematic diagram showing the effect of ammonia decomposition rate on equivalence ratio (left) and tail gas temperature (right) in Experiment Example 1 of this application.

[0036] Figures 7(a), 7(b), and 7(c) are schematic diagrams showing the effects of ammonia decomposition rate on the emissions of nitric oxide, nitrogen dioxide, and nitrous oxide in Experimental Example 1 of this application.

[0037] Figure 8 This is a schematic diagram showing the effect of total ammonia flow rate on internal combustion engine torque in Experimental Example 2 of this application.

[0038] Figure 9This is a schematic diagram showing the effect of total ammonia flow rate on internal combustion engine power in Experimental Example 2 of this application.

[0039] Figure 10 This is a schematic diagram showing the effect of total ammonia flow rate on the thermal efficiency of an internal combustion engine in Experimental Example 2 of this application.

[0040] Figure 11 This is a schematic diagram showing the effect of the total ammonia flow rate on the ammonia concentration (left) and ammonia burnout rate (right) in the exhaust gas involved in Experiment Example 2 of this application.

[0041] Figure 12 This is a schematic diagram showing the effect of total ammonia flow rate on equivalence ratio (left) and tail gas temperature (right) in Experiment Example 2 of this application;

[0042] Figures 13(a), 13(b), and 13(c) are schematic diagrams showing the effects of the total ammonia flow rate on the emissions of nitric oxide, nitrogen dioxide, and nitrous oxide in Experimental Example 2 of this application, respectively.

[0043] Figure 14 This is a schematic diagram showing the effect of the equivalence ratio on the torque of an internal combustion engine in Experimental Example 3 of this application.

[0044] Figure 15 This is a schematic diagram showing the effect of the equivalence ratio on the power of an internal combustion engine in Experiment Example 3 of this application.

[0045] Figure 16 This is a schematic diagram showing the effect of equivalence ratio on the thermal efficiency of an internal combustion engine in Experimental Example 3 of this application.

[0046] Figure 17 This is a schematic diagram showing the effect of equivalence ratio on ammonia concentration (left) and ammonia burnout rate (right) in the exhaust gas of an internal combustion engine, as described in Experimental Example 3 of this application.

[0047] Figure 18 This is a schematic diagram showing the effect of the equivalence ratio on the exhaust gas temperature in Experiment Example 3 of this application.

[0048] Figures 19(a), 19(b), and 19(c) are schematic diagrams showing the effects of the equivalence ratio involved in Experiment Example 3 of this application on the concentrations of nitric oxide, nitrogen dioxide, and nitrous oxide in the exhaust gas. Detailed Implementation

[0049] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments. Unless otherwise specified, the raw materials and catalysts in the embodiments of the present application are all purchased through commercial channels.

[0050] like Figure 1As shown, the testing system for the ammonia internal combustion engine in this application includes four main experimental devices: First, an ammonia internal combustion engine and dynamometer system for studying the speed, torque, power, and thermal efficiency of the ammonia-partially decomposed gas internal combustion engine; second, a Fourier transform infrared spectroscopy analyzer for studying the concentration of ammonia and nitrous oxide in the engine exhaust gas; third, a Testo 340 flue gas analyzer for studying the concentrations of oxygen, nitric oxide, and nitrogen dioxide in the exhaust gas after water and ammonia removal from the internal combustion engine; and fourth, a sheathed thermocouple for studying the temperature of the engine exhaust gas. All experiments were conducted at ambient temperature and pressure.

[0051] This application's research on the combustion and emission characteristics of an internal combustion engine based on partially decomposed ammonia gas mainly focuses on three aspects. First, it measures the engine's power characteristics, ammonia burnout rate, and exhaust emissions under different ammonia decomposition rates to clarify the impact of the ammonia decomposition rate on the engine. Next, under a fixed ammonia decomposition rate, it studies the effect of different total ammonia flow rates on the engine's power characteristics, ammonia burnout rate, and exhaust emissions, exploring the influence of total ammonia flow rates on the engine. Finally, under fixed ammonia decomposition rates and total ammonia flow rates, it studies the effect of different equivalence ratios on the engine's power characteristics, ammonia burnout rate, and exhaust emissions, obtaining the influence of the equivalence ratio on the engine.

[0052] Figure 1 The diagram shows the experimental setup of the entire experimental system. The entire experimental system consists of four subsystems: an ammonia internal combustion engine fuel system, an internal combustion engine system, an internal combustion engine dynamometer system, and an internal combustion engine exhaust gas detection system.

[0053] The ammonia internal combustion engine fuel system mainly includes an ammonia cylinder, a hydrogen and nitrogen mixture cylinder, an ammonia flow meter, a hydrogen-nitrogen mixture flow meter, a gas pressure reducing valve, an air filter, an air flow meter, and a gas mixer. The ammonia cylinder and the hydrogen-nitrogen mixture cylinder are both high-pressure cylinders used to supply the fuel gases required for the experiment. The hydrogen-nitrogen mixture cylinder has a hydrogen to nitrogen ratio of 3:1 to simulate ammonia decomposition. The ammonia and hydrogen-nitrogen mixture flow meters control the flow rate of the mixture. Adjusting the flow meters according to experimental requirements allows for different ammonia decomposition rates and different total ammonia flow rates. The gas pressure reducing valve reduces the pressure of the ammonia and hydrogen-nitrogen mixture, preventing excessive pressure from damaging the experimental gas path and internal combustion engine components. The air filter filters impurities from the air drawn into the internal combustion engine. The air flow meter measures the flow rate of the air drawn into the internal combustion engine. A gas mixer is used to mix fuel gases such as ammonia, hydrogen, and nitrogen with the self-inhaled air to facilitate their combustion in an internal combustion engine.

[0054] The internal combustion engine system mainly includes the internal combustion engine used in the experiment and related experimental accessories. The internal combustion engine used in this application is the Yamaha MX400 from Japan, a single-cylinder, four-stroke spark-ignition internal combustion engine. The internal combustion engine dynamometer system is model Weige ACD-11kW, mainly including a control cabinet, a loading cabinet, a loading motor, and speed and torque sensors. The internal combustion engine exhaust gas measurement system mainly includes the measurement of ammonia concentration, nitric oxide concentration, nitrogen dioxide concentration, nitrous oxide concentration, and exhaust gas temperature. A Testo 340 flue gas analyzer is used to measure nitric oxide and nitrogen dioxide in the exhaust gas. A sheathed thermocouple is installed at the exhaust pipe intake of the internal combustion engine to measure the exhaust gas temperature at this location, and a paperless recorder is used to record the measurement data.

[0055] In this scheme, the flow rates of ammonia, hydrogen, and nitrogen are controlled and measured by flow meters. The dynamometer measures the speed and torque of the internal combustion engine based on the partial decomposition of ammonia. The following is the process for calculating the power and thermal efficiency of the internal combustion engine.

[0056] The torque and speed of the ammonia partial decomposition gas internal combustion engine during operation are measured by a dynamometer. The power of the internal combustion engine is calculated as follows, where W is the power of the internal combustion engine in kW. Pi; n is the engine speed in rpm; T is the engine torque in N·m.

[0057]

[0058] The thermal efficiency of an internal combustion engine can be calculated from its power output and the flow rates of ammonia, hydrogen, and nitrogen, using the following formula: where η is the thermal efficiency of the internal combustion engine; W is the power output of the internal combustion engine; W0... NH3 and W H2 The energy input is for ammonia and hydrogen, expressed in J / s. Nitrogen is not included in the calculation because it does not participate in the reaction.

[0059]

[0060] The concentrations of oxygen, nitric oxide, and nitrogen dioxide in the exhaust gas after water and ammonia removal were measured using a Testo 340. The following is the process for calculating the concentrations and equivalence ratios of nitric oxide and nitrogen dioxide in the total exhaust gas. The overall reaction equation for the combustion of partially decomposed ammonia gas in an internal combustion engine is as follows.

[0061]

[0062] Assuming the ammonia supply flow rate in the experiment is Q L / min, the oxygen self-absorbed by the internal combustion engine is Y L / min, and the ammonia flow rate during the reaction is XL / min, the concentration of ammonia in the total exhaust gas and the concentration of oxygen in the exhaust gas after water and ammonia removal can be expressed by the following formulas, where C NH33 / 4X is the concentration of ammonia in the total exhaust gas; CO2 is the concentration of oxygen in the exhaust gas after water and ammonia removal; 3 / 4X is the flow rate of oxygen in the reaction, in L / min; 1 / 2X is the flow rate of nitrogen produced in the reaction, in L / min; 3 / 2X is the flow rate of water produced in the reaction, in L / min; 3.76Y is the flow rate of nitrogen aspirated by the internal combustion engine, in L / min.

[0063]

[0064]

[0065] The concentration C of ammonia in the total exhaust gas, as measured by Fourier transform infrared spectroscopy. NH3 The concentration C of oxygen in the exhaust gas after water and ammonia removal, as measured by the Testo 340 flue gas analyzer. O2 Therefore, by combining the two formulas above, we can calculate the total ammonia flow rate XL / min and the oxygen flow rate YL / min from the internal combustion engine. From this, we can calculate the total exhaust gas flow rate and the exhaust gas flow rate after water and ammonia removal. The calculation process is as follows, where C... 1NO / NO2 C represents the concentrations of nitric oxide and nitrogen dioxide in the total exhaust gas. 2NO / NO2 The concentrations of nitric oxide and nitrogen dioxide in the tail gas after water and ammonia removal are given.

[0066]

[0067] The equivalence ratio of the reaction can be calculated from this, as shown in the following formula, where It is the equivalent ratio.

[0068]

[0069] Given that most current research focuses on the combustion and emission characteristics of internal combustion engines at a specific ammonia decomposition rate, and lacks studies on the impact of ammonia decomposition rate on internal combustion engine systems, this project experimentally investigates the influence of ammonia decomposition rate on the combustion and emission characteristics of internal combustion engines, primarily focusing on three aspects: engine power characteristics, ammonia burnout rate, and nitrogen oxide emission characteristics. This project systematically studies the effects of ammonia decomposition rate, total ammonia flow rate, and equivalence ratio on the combustion and emission characteristics of spark-ignition internal combustion engines. Combustion characteristics include the engine power characteristics and ammonia burnout rate. Power characteristics include studies on engine speed, torque, power, and thermal efficiency; ammonia burnout rate includes the concentration of ammonia in the exhaust gas, ammonia combustion efficiency, exhaust gas temperature, and fuel equivalence ratio. Emission characteristics include the concentrations of nitric oxide, nitrogen dioxide, and nitrous oxide emitted from the exhaust gas of ammonia-fired internal combustion engines.

[0070] Specifically, the study involved the following aspects: First, it systematically investigated the effects of ammonia decomposition rate on the power characteristics, ammonia burnout rate, and emission characteristics of spark-ignition internal combustion engines, obtaining the influence law of different ammonia decomposition rates on internal combustion engines and determining the suitable ammonia decomposition rate for spark-ignition internal combustion engines; Second, it systematically investigated the effects of total ammonia flow rate on the power characteristics, ammonia burnout rate, and emission characteristics of spark-ignition internal combustion engines, obtaining the influence of different total ammonia flow rates on internal combustion engines and determining the appropriate total ammonia flow rate for this internal combustion engine; Third, it systematically investigated the effects of equivalence ratio on the power characteristics, ammonia burnout rate, and emission characteristics of ammonia spark-ignition internal combustion engines, obtaining the influence of different equivalence ratios on internal combustion engines, providing reference value for the equivalence ratio research in the design and operation of ammonia partially decomposed gas internal combustion engines.

[0071] Based on the above research on the application of ammonia in internal combustion engines, a control process for an ammonia internal combustion engine system has been obtained.

[0072] The present application solution will be specifically described below through specific embodiments and experimental examples.

[0073] Example 1

[0074] An ammonia internal combustion engine system includes a fuel supply module and an internal combustion engine module. The internal combustion engine module includes an internal combustion engine body, which is a dual spark plug ignition type internal combustion engine. The fuel supply module is connected to the intake valve of the internal combustion engine body. The fuel supply module is used to supply the required fuel gas to the internal combustion engine module. A catalyst is provided in the ammonia decomposer.

[0075] The fuel supply module includes an ammonia cylinder, a first flow meter, and an ammonia decomposer. The ammonia cylinder is connected to the first flow meter, and the other end of the first flow meter is connected to the ammonia decomposer. A gas pressure reducing valve is installed between the first flow meter and the ammonia decomposer. The opposite end of the first flow meter of the ammonia decomposer is connected to the intake valve of the internal combustion engine. A second flow meter is also installed between the ammonia decomposer and the intake valve. The catalyst includes metallic vanadium.

[0076] Experimental Example 1: Effect of Ammonia Decomposition Rate

[0077] The tests were conducted according to the experimental conditions in Table 1, specifying the flow rates of ammonia, hydrogen, and nitrogen as follows, under a total ammonia flow rate of 25 L / min, during the ammonia decomposition rate variation from 20% to 70%. The experiments revealed that when the ammonia decomposition rate was below 20%, the internal combustion engine performance was poor, and misfires frequently occurred. Conversely, catalysts required for ammonia decomposition rates above 70% were expensive and economically unfeasible. Therefore, an ammonia decomposition rate of 20%–70% was chosen.

[0078] Table 1

[0079]

[0080] 1) The effect of ammonia decomposition rate on power characteristics

[0081] Power is the most fundamental and important performance characteristic of an internal combustion engine. When using partially decomposed ammonia gas as fuel, the power characteristics of burning this gas must first be considered. Therefore, this study first investigates the impact of different ammonia decomposition rates on the power characteristics of an ammonia-fueled internal combustion engine, mainly including engine speed, torque, power, and thermal efficiency.

[0082] Figure 2 The effect of ammonia decomposition rate on the speed and torque of an internal combustion engine was shown. Both speed and torque were experimentally measured under conditions of a total ammonia flow rate of 25 L / min, engine speed of 800–1200 rpm, and ammonia decomposition rate of 20%–70%. Figure 2 It can be seen that as the ammonia decomposition rate increases from 20% to 50%, the maximum speed of the internal combustion engine increases from 2100 rpm to 3000 rpm. Further increasing the ammonia decomposition rate from 50% to 70% only increases the maximum speed from 3000 rpm to 3200 rpm. This is mainly because as the ammonia decomposition rate increases, the proportion of hydrogen in the partially decomposed ammonia gas increases, thus increasing the combustible region and combustible limit of the mixture, leading to an increase in the maximum speed of the internal combustion engine. The increase in the maximum speed from 50% to 70% is limited, only increasing from 3000 rpm to 3200 rpm, which is very close to the maximum speed of 3600 rpm for gasoline-powered internal combustion engines.

[0083] Depend on Figure 2 Similarly, it can be seen that under a total ammonia flow rate of 25 L / min and a fixed ammonia decomposition rate, the torque of the internal combustion engine first increases and then decreases as the engine speed increases. During the ammonia decomposition rate variation from 20% to 40%, the engine torque reaches its maximum at 1200 rpm; while during the variation from 50% to 70%, the engine torque reaches its maximum at 1100 rpm. Therefore, it can be concluded that under low decomposition rate conditions, the internal combustion engine reaches its maximum torque at a higher engine speed, while under high decomposition rate conditions, the engine reaches its maximum torque at a lower engine speed. Meanwhile, as the ammonia decomposition rate increases from 20% to 50%, the measured maximum torque increases from 5.7 N·m to 11.2 N·m. This is because as the ammonia decomposition rate increases, the proportion of hydrogen in the mixture increases, which expands the flammability limit of the mixture and increases the flame propagation speed, thereby increasing the reactivity of the fuel. Moreover, the preferential diffusion combustion of hydrogen leads to higher combustion efficiency. In addition, the maximum indicated pressure in the internal combustion engine cylinder increases at this time, which will generate greater torque.

[0084] As the ammonia decomposition rate increased from 50% to 70%, the measured maximum torque decreased from 11.2 N·m to 10.6 N·m. This may be because, with the total fuel energy remaining almost unchanged, the increased ammonia decomposition rate resulted in a larger proportion of nitrogen produced from the ammonia decomposition. Since nitrogen does not participate in the reaction and is directly discharged from the cylinder, it carries away a large amount of heat, causing significant heat loss. This effect is not obvious at low decomposition rates, but it is very significant at high decomposition rates.

[0085] In summary, when the ammonia decomposition rate is 50%, the internal combustion engine speed and torque are basically at their optimal levels.

[0086] Figure 3 The effect of ammonia decomposition rate on the power of an internal combustion engine was shown. Power was experimentally measured under conditions of a total ammonia flow rate of 25 L / min, engine speed of 800–1200 rpm, and ammonia decomposition rate of 20%–70%. Figure 3 It can be seen that as the internal combustion engine speed increases from 800 rpm to 3200 rpm, the measured power first increases and then decreases. The engine power reaches its maximum value at an ammonia decomposition rate of 20% and a speed of 1200 rpm, an ammonia decomposition rate of 30%–60% and a speed of 1500 rpm, and an ammonia decomposition rate of 70% and a speed of 1800 rpm. As the ammonia decomposition rate increases from 20% to 50%, the maximum power of the internal combustion engine increases from 0.73 kW to 1.41 kW. However, as the ammonia decomposition rate increases from 50% to 70%, the maximum power only increases from 1.41 kW to 1.45 kW. This shows that at ammonia decomposition rates of 50%–70%, especially at speeds below 2400 rpm, the engine power remains essentially unchanged.

[0087] In summary, when the ammonia decomposition rate reaches 50%, the maximum power of the internal combustion engine is basically at its optimal level.

[0088] Figure 4 This study demonstrates the effect of ammonia decomposition rate on the thermal efficiency of an internal combustion engine. The thermal efficiency was experimentally measured under conditions of a total ammonia flow rate of 25 L / min, engine speed of 800–1200 rpm, and ammonia decomposition rate of 20%–70%. Figure 4It can be seen that as the engine speed increases from 800 rpm to 1200 rpm, the engine's thermal efficiency first increases and then decreases. The engine reaches its maximum thermal efficiency at 1200 rpm and ammonia decomposition rate of 20%–30%, at 1500 rpm and ammonia decomposition rate of 40%–60%, and at 1800 rpm and ammonia decomposition rate of 70%. As the ammonia decomposition rate increases from 20% to 50%, the maximum thermal efficiency increases from 11.49% to 20.29%. With increasing ammonia decomposition rate, the proportion of hydrogen in the air-fuel mixture increases, which may lead to an increase in the combustion zone within the engine cylinder and an increase in the heat release rate throughout the reaction process. However, as the ammonia decomposition rate increases from 50% to 70%, the engine's thermal efficiency decreases from 20.29% to 20.12%.

[0089] 2) The effect of ammonia decomposition rate on ammonia burnout rate

[0090] To study the combustion of partially decomposed ammonia gas in an internal combustion engine, it is necessary to investigate not only the work done by the combustion of the partially decomposed ammonia gas but also the combustion characteristics of the ammonia itself. However, directly studying the combustion of ammonia within the cylinder of an internal combustion engine is very difficult and requires numerical simulation or other specialized methods. The inventors investigated the combustion of ammonia in an internal combustion engine by studying the emission of ammonia in the exhaust gas, calculating the ammonia burnout rate, and measuring the equivalence ratio of the reaction and the exhaust gas temperature.

[0091] Figure 5 The effect of ammonia decomposition rate on ammonia emissions (left) and ammonia burnout rate (right) in the exhaust gas is shown. In this experiment, ammonia emissions in the exhaust gas were measured under the conditions of a total ammonia flow rate of 25 L / min, a rotation speed of 800–3200 rpm, and ammonia decomposition rates of 30%, 50%, and 70%. Ammonia burnout rate was measured under the experimental conditions of a total ammonia flow rate of 25 L / min, a rotation speed of 1200–2100 rpm, and ammonia decomposition rates of 30%, 50%, and 70%.

[0092] Depend on Figure 5(Left) As can be seen, as the internal combustion engine speed increases from 800 rpm to 3200 rpm, the concentration of ammonia in the exhaust gas first decreases and then remains constant. Below 1200 rpm, the ammonia concentration in the exhaust gas is very high, resulting in significant fuel waste. Above 2100 rpm, although the ammonia concentration in the exhaust gas remains low, the engine power and thermal efficiency are also low. This phenomenon indicates that above 2100 rpm, the increased self-drawn air from the engine leads to a lower ammonia concentration in the exhaust gas. However, the lower power and thermal efficiency at this point suggest the presence of a large amount of unburned ammonia decomposition gas, resulting in fuel waste. Therefore, the suitable engine speed for this partially ammonia-decomposed gas internal combustion engine is 1200 rpm to 2100 rpm.

[0093] Depend on Figure 5 (Left) Similarly, it can be seen that as the ammonia decomposition rate increases from 30% to 70%, the ammonia concentration in the internal combustion engine exhaust gas decreases significantly between 800 rpm and 1200 rpm. However, as the engine speed increases, the ammonia concentration in the exhaust gas remains essentially unchanged. Increasing the ammonia decomposition rate from 30% to 50% significantly reduces the ammonia concentration in the exhaust gas, while simultaneously improving the engine's torque, power, and thermal efficiency. Therefore, increasing the ammonia decomposition rate from 30% to 50% promotes the combustion of partially decomposed ammonia gas. Furthermore, it can be observed that a higher ammonia decomposition rate is required at low engine speeds to reduce ammonia emissions in the exhaust gas.

[0094] Next, the ammonia burnout rate is calculated by measuring the ammonia concentration in the exhaust gas. The ammonia burnout rate is the ratio of the total ammonia flow rate reacting to the total ammonia flow rate input during the combustion process in an internal combustion engine. The ammonia burnout rate directly reflects the combustion status of ammonia in an internal combustion engine. The formula for calculating the ammonia burnout rate is as follows, where Z is the ammonia burnout rate, and Q... r Q represents the total flow rate of ammonia gas during the reaction. t This represents the total flow rate of the input ammonia gas.

[0095]

[0096] Depend on Figure 5 (Right) The effects of internal combustion engine speed and ammonia decomposition rate on ammonia burnout rate can be visually observed: as the internal combustion engine speed increases from 1200 rpm to 2100 rpm, the ammonia burnout rate increases; as the ammonia decomposition rate increases from 30% to 70%, the ammonia burnout rate also increases. Therefore, it can be concluded that in this internal combustion engine, increasing the engine speed by 1200~2100 rpm and increasing the ammonia decomposition rate by 30%~70% can promote ammonia combustion, improve ammonia combustion efficiency, and increase the ammonia burnout rate.

[0097] Figure 6The effect of ammonia decomposition rate on equivalence ratio and tail gas temperature was shown. In this experiment, the equivalence ratio and tail gas temperature were measured under the conditions of a total ammonia flow rate of 25 L / min, a rotation speed of 1200–2100 rpm, and ammonia decomposition rates of 30%, 50%, and 70%. Figure 6 (Left) It can be seen that as the internal combustion engine speed increases, the amount of naturally aspirated air increases, thus the equivalence ratio generally shows a downward trend. Additionally, as the ammonia decomposition rate increases from 30% to 50%, the equivalence ratio decreases slightly. However, as the ammonia decomposition rate increases from 50% to 70%, the equivalence ratio decreases significantly, dropping by approximately 0.1, at internal combustion engine speeds of 1800 rpm to 2100 rpm.

[0098] Based on the preceding content and the experimental results of ammonia burnout rate under the same conditions, the equivalence ratio decreases with increasing engine speed, while the total ammonia flow rate remains constant at 25 L / min. This indicates that the amount of self-drawn air in the internal combustion engine increases, and after combustion with the partially decomposed ammonia gas, the ammonia burnout rate is improved. Furthermore, increasing the ammonia decomposition rate lowers the equivalence ratio of the internal combustion engine, which also improves the ammonia burnout rate. Therefore, under the conditions of a total ammonia flow rate of 25 L / min, engine speed of 1200–2100 rpm, and ammonia decomposition rates of 30%, 50%, and 70%, lowering the equivalence ratio improves the ammonia burnout rate. This suggests that under the conditions of this experimental example, the internal combustion engine is more suitable for operation under low equivalence ratio conditions.

[0099] Figure 6 (Right) shows the effect of ammonia decomposition rate on exhaust gas temperature. Exhaust gas temperature also reflects the effect of... Figure 6 (Right) It can be seen that as the ammonia decomposition rate increases from 30% to 70%, the exhaust gas temperature decreases. Combined with the previous discussion on ammonia burnout rate, increasing the ammonia decomposition rate lowers the exhaust gas temperature. This decrease in exhaust gas temperature reflects a reduction in heat loss in the internal combustion engine, which improves the combustion efficiency of the partially decomposed ammonia gas, thus increasing the ammonia burnout rate.

[0100] 3) The effect of ammonia decomposition rate on the nitrogen oxide emission characteristics of internal combustion engines

[0101] The combustion products of ammonia-based partial decomposition gas internal combustion engines do not contain carbonaceous substances, but they do contain atmospheric pollutants such as nitric oxide, nitrogen dioxide, and nitrous oxide. Studying the formation patterns of nitrogen oxides and controlling their generation is equally important in research on ammonia-based internal combustion engines. Therefore, this paper explores the formation patterns of nitric oxide, nitrogen dioxide, and nitrous oxide in ammonia-based partial decomposition gas internal combustion engines, providing data and support for the research and control of exhaust pollution from ammonia-based internal combustion engines.

[0102] Figures 7(a), 7(b), and 7(c) show the effects of ammonia decomposition rate on the concentrations of nitric oxide, nitrogen dioxide, and nitrous oxide in the exhaust gas, respectively. In this experiment, the concentrations of nitric oxide, nitrogen dioxide, and nitrous oxide were measured under the conditions of a total ammonia flow rate of 25 L / min, a rotation speed of 1200–2100 rpm, and ammonia decomposition rates of 30%, 50%, and 70%.

[0103] As shown in Figure 7(a), the concentration of nitric oxide in the exhaust gas continuously increases with the engine speed from 1200 rpm to 2100 rpm. Existing research indicates that nitric oxide is mainly generated in the high-temperature combustion zone or near the flame front in ammonia-fueled internal combustion engines. As mentioned earlier, the exhaust gas temperature increases with the engine speed from 1200 rpm to 2100 rpm, which also means an increase in the temperature inside the engine cylinder, leading to a higher nitric oxide concentration. The concentration of nitric oxide in the exhaust gas increases with the ammonia decomposition rate from 30% to 70% because the increased ammonia decomposition rate leads to a higher proportion of hydrogen in the mixture, increasing the flame propagation speed and resulting in higher pressure and temperature inside the engine cylinder, ultimately leading to an increase in the nitric oxide concentration in the exhaust gas.

[0104] Figure 7(b) shows the effect of ammonia decomposition rate on nitrogen dioxide emissions. As can be seen from Figure 7(b), the concentration of nitrogen dioxide in the exhaust gas increases with increasing engine speed from 1200 rpm to 2100 rpm. The concentration of nitrogen dioxide in the exhaust gas also increases with increasing ammonia decomposition rate from 30% to 70%. The emission patterns of nitrogen dioxide and nitric oxide are consistent; the formation of nitrogen dioxide is closely related to that of nitric oxide, and the difference in their concentrations is only in magnitude.

[0105] Figure 7(c) shows the effect of ammonia decomposition rate on nitrous oxide emissions. As shown in Figure 7(c), the concentration of nitrous oxide in the exhaust gas increases with engine speed from 1200 rpm to 2100 rpm. Furthermore, the concentration of nitrous oxide in the exhaust gas continues to rise as the ammonia decomposition rate increases from 30% to 70%. It is noteworthy that nitrous oxide is also a greenhouse gas contributing to global warming, with an effect 265 times greater than that of carbon dioxide. However, according to experimental data analysis, the emission concentration of nitrous oxide in internal combustion engines using partially decomposed ammonia is still relatively low. Therefore, ammonia as a fuel has significant potential for reducing greenhouse gas emissions.

[0106] Figures 7(a), 7(b), and 7(c) show that under the experimental conditions, the emissions of nitric oxide, nitrogen dioxide, and nitrous oxide in the exhaust gas exhibit the same trend, with higher concentrations at higher engine speeds and higher decomposition rates. In the exhaust gas emissions from internal combustion engines containing partially decomposed ammonia, nitric oxide concentration is the highest, while nitrogen dioxide and nitrous oxide concentrations are similar, but one order of magnitude lower than nitric oxide.

[0107] In summary, based on the experimental results, increasing the ammonia decomposition rate and the hydrogen ratio enhances the reaction activity, which can improve the power characteristics of the internal combustion engine and the combustion characteristics of ammonia. However, it will also increase the emission of nitrogen oxides in the exhaust gas of the internal combustion engine.

[0108] Based on the above research, the following analytical conclusions can be drawn:

[0109] At a total ammonia flow rate of 25 L / min, as the ammonia decomposition rate increases from 20% to 50%, the proportion of hydrogen in the partially decomposed ammonia gas increases, promoting ammonia combustion and significantly increasing the engine speed, torque, power, and thermal efficiency. However, as the ammonia decomposition rate continues to increase from 50% to 70%, the engine speed increases only slightly, suggesting that the promoting effect of hydrogen on the combustion of partially decomposed ammonia gas is limited within this range. As the ammonia decomposition rate increases from 50% to 70%, the engine torque, power, and thermal efficiency remain essentially constant; however, compared to gasoline fuel, the engine's torque, power, and thermal efficiency are lower.

[0110] In ammonia-partially decomposed gas internal combustion engines, a 50% ammonia decomposition rate optimizes the engine's power characteristics. Furthermore, to achieve higher thermal efficiency, a lower ammonia decomposition rate is required at low engine speeds, while a higher rate is needed at high engine speeds.

[0111] As the ammonia decomposition rate increases from 30% to 70%, the concentration of ammonia in the exhaust gas increases significantly at low speeds, while at high speeds, the concentration remains essentially unchanged. Furthermore, as the ammonia decomposition rate increases from 30% to 70%, the ammonia burnout rate significantly improves. Increasing the ammonia decomposition rate also results in a decrease in exhaust gas temperature, reducing heat loss and improving combustion efficiency, thereby enhancing the thermal efficiency of the internal combustion engine.

[0112] The concentrations of nitric oxide, nitrogen dioxide, and nitrous oxide in the exhaust gas of ammonia-fueled internal combustion engines increase with increasing engine speed. In ammonia-partially decomposed gas internal combustion engines, nitric oxide is the primary pollutant in the exhaust gas, while nitrogen dioxide and nitrous oxide are relatively less abundant. As the ammonia decomposition rate increases from 30% to 70%, the increased proportion of hydrogen leads to higher combustion temperatures and pressures, resulting in a significant increase in the concentrations of nitric oxide, nitrogen dioxide, and nitrous oxide in the exhaust gas. Therefore, increasing the ammonia decomposition rate improves the engine's power characteristics and promotes ammonia combustion, but it also leads to higher nitrogen oxide emissions.

[0113] Therefore, based on the fact that the power characteristics of the internal combustion engine are basically optimal at a 50% ammonia decomposition rate, the ammonia decomposition rate is controlled at around 50% in the control process of the ammonia internal combustion engine.

[0114] Experiment Example 2: The Effect of Total Ammonia Flow Rate

[0115] In the previous study on ammonia decomposition rate, it was found that the power characteristics of the internal combustion engine were essentially optimal at a 50% ammonia decomposition rate, and this 50% decomposition rate was closer to actual operating conditions. Based on this, subsequent research was conducted on the basis of a 50% ammonia decomposition rate. During the actual operation of an ammonia-fueled internal combustion engine, the fuel quantity, i.e., the total ammonia flow rate, has a significant impact on combustion and emissions. Therefore, this experimental case study investigated the power characteristics, ammonia burnout rate, and nitrogen oxide emissions of the internal combustion engine under different total ammonia flow rates, exploring the suitable range of total ammonia flow rates for this partially decomposed ammonia internal combustion engine.

[0116] Table 2 shows the set flow rates of ammonia, hydrogen, and nitrogen when the total ammonia flow rate varied from 15 to 25 L / min under a 50% ammonia decomposition rate. Subsequent experiments were conducted according to the experimental conditions set in the table. To ensure the accuracy of the experimental results, all experiments were performed at least three times.

[0117] Table 2

[0118]

[0119] 1) The effect of total ammonia flow rate on the power characteristics of internal combustion engines

[0120] Fuel quantity has a direct impact on the power of internal combustion engines. Within a certain range, increasing the fuel quantity allows more fuel to burn, release heat, and perform work in the engine, thus increasing its power. However, due to the engine's mechanical structure and air limitations, exceeding a certain fuel quantity can lead to incomplete combustion and may even cause a decrease in engine power. Therefore, it is essential to investigate the impact of total ammonia flow rate on the power characteristics of internal combustion engines.

[0121] Figure 8 The effect of total ammonia flow rate on the torque of an internal combustion engine is shown. The torque was experimentally measured under conditions of 50% ammonia decomposition rate, engine speed of 1200–2100 rpm, and total ammonia flow rate of 15–25 L / min. Figure 8It can be seen that, at a 50% ammonia decomposition rate and an internal combustion engine speed of 1200-2100 rpm, as the total ammonia flow rate increases from 15 L / min to 22.5 L / min, the maximum torque of the internal combustion engine at 1200 rpm increases from 6.5 N·m to 11.7 N·m. However, when the total ammonia flow rate increases from 22.5 L / min to 25 L / min, the maximum torque of the internal combustion engine at 1200 rpm decreases from 11.7 N·m to 10.32 N·m, and with the increase of speed, the torque at a total ammonia flow rate of 25 L / min is basically equal to that at a total ammonia flow rate of 22.5 L / min. Based on the above analysis, it can be concluded that when the total ammonia flow rate increases from 15 L / min to 22.5 L / min, the internal combustion engine torque increases, while when it increases to 25 L / min, the torque remains unchanged or decreases slightly. Overall, under the conditions of this experiment, when the total ammonia flow rate exceeds 25 L / min, the torque of the internal combustion engine will decrease slightly.

[0122] Figure 9 The effect of total ammonia flow rate on the power of an internal combustion engine was shown. The power was experimentally measured under the conditions of 50% ammonia decomposition rate, engine speed of 1200–2100 rpm, and total ammonia flow rate of 15–25 L / min. Figure 9 It can be seen that, under the conditions of 50% ammonia decomposition rate and an internal combustion engine speed of 1200~2100 ppm, as the total ammonia flow rate increases from 15 L / min to 22.5 L / min, the maximum power of the internal combustion engine increases from 0.82 kW to 1.94 kW. However, at an internal combustion engine speed of 1200 rpm, when the total ammonia flow rate increases from 22.5 L / min to 25 L / min, the maximum power of the internal combustion engine decreases from 1.49 kW to 1.31 kW, and the power of the internal combustion engine remains basically unchanged as the engine speed ranges from 1500 to 2100 rpm.

[0123] Figure 10 The effect of total ammonia flow rate on the thermal efficiency of an internal combustion engine was demonstrated. The thermal efficiency was experimentally measured under conditions of 50% ammonia decomposition rate, engine speed of 1200–2100 rpm, and total ammonia flow rate of 15–25 L / min. Figure 10 It can be seen that, under the conditions of 50% ammonia decomposition rate and internal combustion engine speed of 1200~2100 rpm, as the total ammonia flow rate increases from 15 L / min to 22.5 L / min, the maximum thermal efficiency of the internal combustion engine increases from 20.1% to 23.80%. However, as the total ammonia flow rate increases from 22.5 L / min to 25 L / min, the thermal efficiency of the internal combustion engine decreases.

[0124] Analysis of the above results reveals that under ammonia flow rates of 15–22.5 L / min, the torque, power, and thermal efficiency of the internal combustion engine all increase significantly. However, under ammonia flow rates of 22.5–25 L / min, these parameters decrease. Therefore, it can be concluded that increasing the ammonia flow rate can replicate the effect of increasing the output power of traditional fuels, but this requires a certain flow rate range. In this experimental example, the maximum ammonia flow rate for the internal combustion engine was 22.5 L / min.

[0125] 2) The effect of total ammonia flow rate on ammonia burnout rate in internal combustion engines

[0126] The combustion of ammonia can be directly studied by measuring the ammonia burnout rate, thereby determining the optimal range of total ammonia flow rate for internal combustion engines under different operating conditions.

[0127] Figure 11 The effect of total ammonia flow rate on ammonia concentration and ammonia burnout rate in the exhaust gas of an internal combustion engine is shown. Both ammonia concentration and burnout rate were experimentally measured under conditions of 50% ammonia decomposition rate, engine speed of 1200–2100 rpm, and total ammonia flow rate of 15–25 L / min.

[0128] Depend on Figure 11 (Left) It can be seen that as the total ammonia flow rate increases from 15 L / min to 22.5 L / min, the ammonia concentration in the engine exhaust increases, especially in the 1200-1500 rpm range. As the total ammonia flow rate increases from 22.5 L / min to 25 L / min, the ammonia concentration in the exhaust increases significantly, by approximately 0.1%. This explains why the engine torque, power, and thermal efficiency are lower when the total ammonia flow rate increases from 22.5 L / min to 25 L / min. The increase in ammonia flow rate from 22.5 L / min to 25 L / min results in a large amount of unburned ammonia fuel in the exhaust, leading to fuel waste and a decrease in the engine's thermal efficiency.

[0129] Figure 11 (Right) This shows the effect of total ammonia flow rate on the ammonia burnout rate of an internal combustion engine, further illustrating the combustion characteristics of ammonia. As the total ammonia flow rate increased from 15 L / min to 17.5 L / min, the ammonia burnout rate decreased at 1200 rpm; it remained unchanged at 1500 rpm; and increased between 1800 and 2100 rpm. As the total ammonia flow rate increased from 17.5 L / min to 25 L / min, the ammonia burnout rate continuously decreased. Overall, under the experimental conditions, a lower total ammonia flow rate resulted in a higher ammonia burnout rate.

[0130] Figure 12 The effect of total ammonia flow rate on equivalence ratio (left) and exhaust gas temperature (right) is shown. Both equivalence ratio and exhaust gas temperature were experimentally measured under the conditions of 50% ammonia decomposition rate, 1200-2100 rpm rotation speed, and 15-25 L / min total ammonia flow rate.

[0131] Depend on Figure 12 (Left) It can be seen that as the total ammonia flow rate increases, the equivalence ratio increases from about 0.7 to about 0.9. With the engine speed of the ammonia-fueled internal combustion engine remaining constant, the amount of air drawn into the engine remains constant, while the total ammonia flow rate entering the cylinder increases from 15 L / min to 25 L / min. The lack of air limits the combustion of some of the ammonia decomposition gas, which in turn limits energy conversion. This is particularly evident at a total ammonia flow rate of 25 L / min. Under the condition of a total ammonia flow rate of 25 L / min, the power characteristics of the internal combustion engine deteriorate, the ammonia concentration in the exhaust gas increases significantly, and the ammonia burnout rate is the lowest.

[0132] Figure 12 (Right) It can be seen that as the total ammonia flow rate increases, the exhaust gas temperature of the internal combustion engine rises, reaching its highest point at a total ammonia flow rate of 25 L / min. In an ammonia-fueled internal combustion engine, the higher the total ammonia flow rate, the more exhaust gas is produced, and the more heat is carried away by the exhaust gas, especially under the condition of a total ammonia flow rate of 25 L / min, where heat loss is greatest, resulting in lower thermal efficiency of the internal combustion engine. Exhaust gas recirculation (EGR) can be used to reduce the exhaust gas temperature and can also utilize the unburned ammonia in the exhaust gas to partially decompose the gases, effectively promoting combustion in the internal combustion engine. Therefore, EGR technology can be used to solve the above problems.

[0133] 3) The impact of total ammonia flow rate on the nitrogen oxide emission characteristics of internal combustion engines

[0134] Fuel quantity has a direct impact on the exhaust emissions of internal combustion engines; the composition and concentration of various components in the exhaust gas differ under different fuel quantities. Therefore, it is essential to study the effect of different total ammonia flow rates on the emission characteristics of internal combustion engines in order to ensure that they meet emission standards.

[0135] Figures 13(a), 13(b), and 13(c) show the effects of total ammonia flow rate on the concentrations of nitric oxide, nitrogen dioxide, and nitrous oxide in the exhaust gas, respectively. The concentrations of nitric oxide, nitrogen dioxide, and nitrous oxide were experimentally measured under the conditions of 50% ammonia decomposition rate, rotation speed of 1200–2100 rpm, and total ammonia flow rate of 15–25 L / min.

[0136] Figure 13(a) shows the effect of total ammonia flow rate on nitric oxide emissions in the exhaust gas. As shown in Figure 13(a), when the total ammonia flow rate increases from 15 L / min to 17.5 L / min, the concentration of nitric oxide in the exhaust gas decreases with increasing rotational speed; when the total ammonia flow rate increases from 20 L / min to 22.5 L / min, the concentration of nitric oxide first increases and then decreases with increasing rotational speed; when the total ammonia flow rate is 25 L / min, the concentration of nitric oxide increases with increasing rotational speed. Within the experimental range, the maximum nitric oxide concentration is 4300 ppm, at which point the equivalence ratio is 0.86. Within the experimental range, the minimum nitric oxide concentration is 260 ppm, at which point the equivalence ratio is 0.94. The nitric oxide concentration is mainly affected by the concentration of O / H free radicals, and its net generation is the generation minus the consumption. Under these conditions, the ammonia concentration in the exhaust gas is relatively high, approximately 0.8%, indicating that the reaction between nitric oxide and ammonia leads to a significant decrease in its concentration.

[0137] Figure 13(b) shows the effect of total ammonia flow rate on nitrogen dioxide emissions in the exhaust gas. As shown in Figure 13(b), as the engine speed increases from 1200 rpm to 2100 rpm, the nitrogen dioxide concentration in the exhaust gas decreases at total ammonia flow rates of 15 L / min and 17.5 L / min; at total ammonia flow rates of 20 L / min and 22.5 L / min, the nitrogen dioxide concentration first increases and then decreases; at a total ammonia flow rate of 25 L / min, the nitrogen dioxide concentration increases. Overall, the changes in nitrogen dioxide concentration follow the same pattern as those in nitric oxide concentration, differing only in order of magnitude.

[0138] Figure 13(c) shows the effect of total ammonia flow rate on nitrous oxide emissions in the exhaust gas. As can be seen from Figure 13(c), unlike nitric oxide and nitrogen dioxide, at engine speeds of 1200–2100 rpm, the nitrous oxide concentration continuously decreases as the total ammonia flow rate increases from 15 L / min to 25 L / min. It is well known that nitrous oxide is more easily generated under low-temperature conditions and with less fuel. Figure 11 (Right) It can be seen that the temperature increases with increasing engine speed and total ammonia flow rate. High temperature negatively impacts the conversion of nitric oxide to nitrous oxide, resulting in lower nitrous oxide formation. Therefore, the nitrous oxide concentration decreases with increasing engine speed. Furthermore, increasing the total ammonia flow rate also reduces nitrous oxide formation, leading to lower exhaust gas concentration. Therefore, under conditions of low engine speed and high flow rate, minimal nitrous oxide emissions can be achieved.

[0139] In this experimental example, by studying the combustion and emission characteristics of an internal combustion engine with partially decomposed ammonia gas at a total ammonia flow rate of 15-25 L / min under a 50% ammonia decomposition rate, the study revealed the influence of total ammonia flow rate on the engine's power characteristics, ammonia burnout rate, and nitrogen oxide emissions, leading to the following conclusions:

[0140] Under a 50% ammonia decomposition rate, increasing the total ammonia flow rate from 15 L / min to 22.5 L / min significantly increases the torque, power, and thermal efficiency of the internal combustion engine. However, as the total ammonia flow rate increases to 25 L / min, at a speed of 1200 rpm, the incomplete combustion of partially decomposed ammonia gas leads to a slight decrease in the engine's torque, power, and thermal efficiency. Within the speed range of 1500–2100 rpm, the torque, power, and thermal efficiency remain essentially unchanged.

[0141] Under 50% ammonia decomposition rate and corresponding experimental conditions, the optimal power characteristics of this ammonia-partially decomposed gas internal combustion engine are observed at a total ammonia flow rate of 22.5 L / min. Increasing the total ammonia flow rate to 25 L / min does not significantly improve the engine's power characteristics, and may even reduce them, resulting in wasted ammonia fuel. Therefore, the maximum total ammonia flow rate for this ammonia-partially decomposed gas internal combustion engine is approximately 22.5 L.

[0142] The results of measuring the ammonia concentration in the exhaust gas showed that as the total ammonia flow rate increased, the ammonia concentration in the exhaust gas continued to rise. In particular, under the condition of a total ammonia flow rate of 25 L / min, the ammonia concentration in the exhaust gas increased by about 0.1%, and a large amount of unburned fuel was directly discharged from the internal combustion engine cylinder. At this time, the ammonia combustion rate reached the lowest level, which was 96.2%.

[0143] As the total ammonia flow rate increases from 15 L / min to 25 L / min, the equivalence ratio increases from 0.7 to 0.9. At the lowest possible torque, power, and thermal efficiency of the internal combustion engine, the equivalence ratio is above 0.9. With increasing total ammonia flow rate, the exhaust gas temperature of the internal combustion engine continuously rises, and the exhaust gas carries away more heat. Therefore, the torque, power, and thermal efficiency are lowest at a total ammonia flow rate of 25 L / min.

[0144] The concentrations of nitric oxide, nitrogen dioxide, and nitrous oxide were measured within the range of total ammonia flow rate from 15 L / min to 25 L / min. The results showed that the concentrations of nitric oxide and nitrogen dioxide exhibited consistent patterns, differing only in magnitude. At speeds of 1200–2100 rpm and at flow rates of 15 L / min and 17.5 L / min, the concentrations of nitric oxide and nitrogen dioxide continuously decreased; at flow rates of 20 L / min and 22.5 L / min, the concentrations of nitric oxide and nitrogen dioxide first increased and then decreased; at a flow rate of 25 L / min, the concentrations of nitric oxide and nitrogen dioxide continuously decreased. Conversely, as the total ammonia flow rate increased, the concentration of nitrous oxide continuously decreased. Analysis revealed that when the ammonia concentration in the exhaust gas was high, the nitrogen oxide concentration decreased; conversely, when the ammonia concentration in the exhaust gas was low, the nitrogen oxide concentration increased.

[0145] Therefore, a total ammonia flow rate of 20~22.5 L / min is selected.

[0146] Experiment Example 3 Effect of Equivalent Ratio

[0147] The previous study explored the effects of ammonia decomposition rate and total ammonia flow rate on the ammonia partially decomposed gas internal combustion engine, and clarified the optimal ammonia decomposition rate and total ammonia flow rate for this engine. The equivalence ratio is also crucial for ammonia partially decomposed gas internal combustion engines, reflecting the amount of air required for fuel combustion. This chapter investigates the effects of different equivalence ratios on the engine's power characteristics, ammonia burnout rate, and oxy-oxide emission characteristics under conditions of 50% ammonia decomposition rate and 20 L / min total ammonia flow rate, deriving a suitable equivalence ratio range for the operation of this ammonia partially decomposed gas internal combustion engine.

[0148] Table 3 shows the experimental conditions for different equivalence ratios under the conditions of 50% ammonia decomposition rate, a total ammonia flow rate of 20 L / min, and a rotation speed of 1200 rpm. Subsequent experiments were conducted according to the experimental conditions set in the table. To ensure the accuracy of the experimental results, all experiments were performed at least three times.

[0149] In this experiment, the total ammonia flow rate of the internal combustion engine was fixed at 20 L / min. Therefore, the effect of the equivalence ratio on the power characteristics of the internal combustion engine actually reflects the effect of the air volume on the power characteristics of the internal combustion engine during operation.

[0150] Table 3

[0151]

[0152] 1) The effect of equivalence ratio on the power characteristics of internal combustion engines

[0153] Figure 14The effect of equivalence ratio on the torque of an internal combustion engine is shown. The torque was experimentally measured under the conditions of 50% ammonia decomposition rate, 20 L / min total ammonia flow rate, 1200 rpm engine speed, and equivalence ratio of 0.84 to 1.39.

[0154] Depend on Figure 14 It is known that as the equivalence ratio increases, the torque of the internal combustion engine first increases and then decreases. Under experimental conditions, the equivalence ratio reaches its maximum torque at 1.12. When the equivalence ratio is small, the amount of fuel in the internal combustion engine remains constant, and excess air carries away a large amount of heat during combustion, reducing the engine's output torque. Therefore, the torque increases with the increase of the equivalence ratio. Studies have found that as the equivalence ratio increases within the range of 0.6 to 1.1, the flame propagation speed of ammonia and hydrogen continuously increases, and the flame propagation speed of the ammonia-hydrogen mixture is faster under low equivalence ratio conditions than under high equivalence ratio conditions. When the equivalence ratio is greater than 1.12, as the equivalence ratio increases, the amount of fuel remains constant, but the amount of air drawn into the internal combustion engine decreases. The lack of sufficient oxygen worsens the combustion process, leading to a decrease in engine torque.

[0155] Figure 15 This demonstrates the effect of equivalence ratio on the power of an internal combustion engine. The engine power was experimentally measured under conditions of 50% ammonia decomposition rate, 20 L / min total ammonia flow rate, 1200 rpm engine speed, and equivalence ratios ranging from 0.84 to 1.39. Figure 15 It can be seen that as the equivalence ratio increases, the power of the internal combustion engine first increases and then decreases. Under experimental conditions, consistent with torque, the equivalence ratio is also 1.12 when the internal combustion engine reaches its maximum power. Before the equivalence ratio is below 1.12, as the equivalence ratio increases, the amount of fuel in the internal combustion engine remains constant, the excess air decreases, reducing combustion heat loss, and more heat is used for work, increasing the output power. However, when the equivalence ratio is above 1.12, the increased equivalence ratio results in a lack of air in the internal combustion engine, while the fuel remains constant, causing a large amount of fuel combustion to deteriorate, leading to less work done by the internal combustion engine and a decrease in power. Consistent with torque, the internal combustion engine has a higher power in the range of equivalence ratios of 0.98 to 1.29. Within this range, the combustion of the internal combustion engine is better, the internal combustion engine does more work, and the power is greater.

[0156] Figure 16 This demonstrates the effect of equivalence ratio on the thermal efficiency of an internal combustion engine. The engine's thermal efficiency was measured under experimental conditions: an ammonia decomposition rate of 50%, a total ammonia flow rate of 20 L / min, an engine speed of 1200 rpm, and an equivalence ratio ranging from 0.84 to 1.39. Figure 16It can be seen that as the equivalence ratio increases, the thermal efficiency of an internal combustion engine first increases and then decreases. Under experimental conditions, consistent with torque and power, the equivalence ratio is also 1.12 when the internal combustion engine reaches its maximum thermal efficiency. When the equivalence ratio is below 1.12, as the equivalence ratio increases, the amount of fuel in the internal combustion engine remains constant, resulting in excess air in the engine. This reduces the heat carried away by the air during combustion, minimizing heat loss and increasing the engine's thermal efficiency. However, when the equivalence ratio is above 1.12, as the equivalence ratio increases, the amount of air in the engine becomes insufficient, causing some fuel to not participate in combustion and reducing thermal efficiency. Consistent with torque and power, to maintain a high thermal efficiency, the equivalence ratio should be within the range of 0.98 to 1.29.

[0157] 2) Effect of equivalence ratio on ammonia burnout rate in internal combustion engines

[0158] The stoichiometric ratio has a significant impact on the combustion of ammonia. Therefore, by studying the effect of the stoichiometric ratio on the ammonia burnout rate, a suitable stoichiometric ratio range for the internal combustion engine can be determined, providing a theoretical basis for the mechanical design and practical application of ammonia internal combustion engines.

[0159] Figure 17 The effect of equivalence ratio on ammonia concentration (left) and ammonia burnout rate (right) in the exhaust gas of an internal combustion engine is shown. Ammonia concentration and ammonia burnout rate were measured under experimental conditions of 50% ammonia decomposition rate, 20 L / min total ammonia flow rate, 1200 rpm engine speed, and equivalence ratios of 0.84–1.39.

[0160] Depend on Figure 17 (Left) It can be seen that as the equivalence ratio increases, when the equivalence ratio is less than 1.23, the ammonia concentration in the exhaust gas is around 0.6%, showing a slight increase. However, when the equivalence ratio is greater than 1.23, the ammonia concentration in the exhaust gas increases significantly. When the equivalence ratio is 1.39, the ammonia concentration in the exhaust gas can even reach 2.1%, indicating that a large amount of fuel ammonia in the exhaust gas is unburned, and the combustion process in the internal combustion engine lacks oxygen. The results show that to maintain a low ammonia concentration in the exhaust gas of an internal combustion engine, the equivalence ratio needs to be below 1.23.

[0161] Depend on Figure 17 (Right) It can be seen that when the equivalence ratio increases from 0.84 to 1.12, the ammonia burnout rate in the exhaust gas is around 97%, and it increases slightly with the increase of the equivalence ratio. However, when the equivalence ratio is greater than 1.12, the ammonia burnout rate decreases significantly, reaching a minimum of 89% at an equivalence ratio of 1.39. When the equivalence ratio is below 1.12, the ammonia burnout rate in the internal combustion engine is relatively high, generally remaining around 97%, indicating good ammonia combustion. Conversely, when the equivalence ratio is greater than 1.12, the ammonia combustion in the internal combustion engine is poor, and the ammonia burnout rate decreases. In summary, when the equivalence ratio is kept below 1.12, the ammonia burnout rate in the internal combustion engine is relatively high.

[0162] Figure 18 The effect of equivalence ratio on the exhaust gas temperature of an internal combustion engine is shown. The exhaust gas temperature was experimentally measured under the conditions of 50% ammonia decomposition rate, 20 L / min total ammonia flow rate, 1200 rpm engine speed, and equivalence ratios ranging from 0.84 to 1.39. Figure 18 It can be seen that as the equivalence ratio increases from 0.84 to 0.98, the exhaust gas temperature of the internal combustion engine rises slightly, reaching its maximum temperature; as the equivalence ratio increases from 0.98 to 1.23, the exhaust gas temperature decreases slowly; and as the equivalence ratio increases from 1.23 to 1.39, the exhaust gas temperature decreases significantly, reaching its lowest point. The results indicate that when the equivalence ratio is greater than 1.23, the fuel combustion in the cylinder is poor, the cylinder temperature decreases significantly, leading to a reduction in exhaust gas temperature.

[0163] 3) The effect of equivalence ratio on the nitrogen oxide emission characteristics of internal combustion engines

[0164] The study on the influence of equivalence ratio on the nitrogen oxide emission characteristics of internal combustion engines mainly reflects the variation law of component concentration of combustion products formed after the combustion of ammonia partial decomposition gas with different air volumes in internal combustion engines.

[0165] Figures 19(a), 19(b), and 19(c) show the effects of equivalence ratio on the concentrations of nitric oxide, nitrogen dioxide, and nitrous oxide in the exhaust gas, respectively. The concentrations of nitric oxide, nitrogen dioxide, and nitrous oxide were experimentally measured under the conditions of 50% ammonia decomposition rate, 20 L / min total ammonia flow rate, 1200 rpm rotation speed, and equivalence ratios ranging from 0.84 to 1.39.

[0166] As shown in Figure 19(a), the concentration of nitric oxide in the exhaust gas decreases with increasing equivalence ratio. When the equivalence ratio is less than 1.12, the nitric oxide concentration decreases relatively slowly, while when the equivalence ratio is greater than 1.12, the nitric oxide concentration in the exhaust gas drops sharply to around 1100 ppm. The results indicate that when the equivalence ratio is less than 1.12, the torque, power, and thermal efficiency of the internal combustion engine gradually increase with increasing equivalence ratio, indicating that the fuel combustion in the internal combustion engine cylinder is good at this time, and more ammonia fuel is converted into nitrogen. However, when the equivalence ratio is greater than 1.12, the torque, power, and thermal efficiency of the internal combustion engine decrease with increasing equivalence ratio, the combustion condition of the internal combustion engine begins to deteriorate, the ammonia in the internal combustion engine cylinder is incompletely burned, and the remaining ammonia undergoes a reduction reaction with nitric oxide, leading to a sharp decrease in the nitric oxide concentration in the exhaust gas of the internal combustion engine.

[0167] As shown in Figure 19(b), the nitrogen dioxide concentration in the exhaust gas first increases and then decreases with increasing equivalence ratio. When the equivalence ratio is less than 1.05, the nitrogen dioxide concentration in the exhaust gas increases slightly with increasing equivalence ratio. However, when the equivalence ratio is greater than 1.05, the nitrogen dioxide concentration in the exhaust gas decreases significantly with increasing equivalence ratio. Nitrogen dioxide is mainly generated from nitric oxide; therefore, the change in nitrogen dioxide concentration in the exhaust gas is closely related to nitric oxide. When the equivalence ratio is less than 1.05, the nitric oxide concentration remains at a high level, resulting in a high nitrogen dioxide concentration, which may even increase slightly. When the equivalence ratio is greater than 1.05, the concentration of nitric oxide from combustion products begins to decrease, leading to a continuous decrease in the nitrogen dioxide concentration in the exhaust gas. As shown in Figure 19(c), the nitrous oxide concentration in the exhaust gas first increases and then decreases with increasing equivalence ratio. The change pattern of nitrous oxide concentration is consistent with that of nitrogen dioxide.

[0168] Overall, nitric oxide is the main exhaust pollutant in internal combustion engines that partially decompose ammonia. During the reaction process, nitrogen dioxide and nitrous oxide are mainly formed from nitric oxide. The formation of nitrous oxide accounts for no more than 30% of the total consumption of nitric oxide, while nitrogen dioxide accounts for no more than 5%. The formation of nitrogen dioxide and nitrous oxide in internal combustion engines is also closely related to nitric oxide, but the relationship among the three is quite complex and requires further research.

[0169] This experimental example investigated the effects of equivalence ratio on the power characteristics, ammonia burnout rate, and nitrogen oxide emissions of an internal combustion engine under conditions of 50% ammonia decomposition rate, a total ammonia flow rate of 20 L / min, and 1200 rpm, within the equivalence ratio range of 0.84 to 1.39. The main findings are as follows:

[0170] As the equivalence ratio gradually increases, the torque, power, and thermal efficiency of an internal combustion engine first increase and then decrease. When the equivalence ratio is less than 1.12, the torque, power, and thermal efficiency of the internal combustion engine gradually increase with the increase of the equivalence ratio; when the equivalence ratio is greater than 1.12, the torque, power, and thermal efficiency of the internal combustion engine decrease with the increase of the equivalence ratio. At an equivalence ratio of 1.12, the torque, power, and thermal efficiency are at their maximum.

[0171] Ammonia partially decomposed gas exhibits good power characteristics within an equivalence ratio range of 0.98 to 1.29, indicating good combustion performance in the internal combustion engine.

[0172] The ammonia concentration in the exhaust gas increases with the increase of the equivalence ratio. When the equivalence ratio is less than 1.23, the ammonia concentration in the exhaust gas increases slightly and remains at around 0.6%. However, when the equivalence ratio is greater than 1.23, due to the lack of air in the internal combustion engine, combustion deteriorates and the ammonia concentration in the exhaust gas increases significantly, resulting in fuel waste.

[0173] As the equivalence ratio increases, the ammonia burnout rate increases slightly when the equivalence ratio is less than 1.12, but decreases significantly when the equivalence ratio is greater than 1.12. Therefore, to maintain a high ammonia burnout rate in an ammonia internal combustion engine, the equivalence ratio should not be lower than 1.12.

[0174] When the equivalence ratio increases from 0.84 to 0.98, the exhaust gas temperature of the internal combustion engine rises slightly; when the equivalence ratio increases from 0.98 to 1.23, the exhaust gas temperature decreases slightly; and when the equivalence ratio is greater than 1.23, the exhaust gas temperature decreases significantly. The results indicate that when the equivalence ratio exceeds 1.23, the in-cylinder combustion conditions of the internal combustion engine are poor, resulting in low in-cylinder temperatures and consequently lower exhaust gas temperatures.

[0175] As the equivalence ratio increases, the concentration of nitric oxide in the exhaust gas initially decreases slowly. When the equivalence ratio is greater than 1.12, due to poor combustion in the internal combustion engine and an increase in ammonia concentration in the exhaust gas, the nitric oxide concentration decreases significantly. The changes in nitrogen dioxide and nitrous oxide follow a similar pattern. As the equivalence ratio increases, when the equivalence ratio is less than 1.05, the concentrations of nitrogen dioxide and nitrous oxide increase slightly due to the higher nitric oxide concentration. However, when the equivalence ratio is greater than 1.05, the concentration of nitric oxide in the exhaust gas begins to decrease, leading to a significant decrease in the concentrations of nitrogen dioxide and nitrous oxide.

[0176] In summary, the equivalence ratio should be selected between 1.05 and 1.12.

[0177] Based on the fact that there is no existing research focus on ammonia internal combustion engines in the current technology, this application investigates the effects of total ammonia flow rate, ammonia decomposition rate, and equivalence ratio on the power characteristics, burnout rate characteristics, and emission characteristics of ammonia internal combustion engines. A practical control process for ammonia internal combustion engines is obtained. This control process not only provides a basis for the design of ammonia internal combustion engines, but also provides a direct and practical solution for the control process during the use of ammonia internal combustion engines.

[0178] This control process ensures good power characteristics of the ammonia internal combustion engine, such as speed, torque, power, and thermal effect. It also ensures good burnout characteristics, such as ammonia concentration in the exhaust gas, combustion efficiency, and fuel equivalence ratio. Furthermore, it takes into account good emission characteristics of nitric oxide, nitrogen dioxide, and nitrous oxide. It is a control process for ammonia internal combustion engines that focuses on power characteristics while taking into account burnout and emission characteristics. It has significant practical application value and is an essential control parameter affecting the operating performance of ammonia internal combustion engines, as well as in the design and operation of ammonia internal combustion engines. Given that no related research has been disclosed in the prior art, the solution proposed in this application also has guiding significance for the application and development of ammonia internal combustion engines in the prior art, and has great social and economic value.

[0179] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A control method for an ammonia internal combustion engine system, characterized in that, The ammonia internal combustion engine system includes a fuel supply module and an internal combustion engine module. The internal combustion engine module includes an internal combustion engine body, which is a dual spark plug ignition type internal combustion engine. The fuel supply module is connected to the intake valve of the internal combustion engine body and is used to supply the required fuel gas to the internal combustion engine module. The fuel supply module includes an ammonia cylinder, a first flow meter, and an ammonia decomposer. The ammonia cylinder is connected to the first flow meter, and the other end of the first flow meter is connected to the ammonia decomposer. A gas pressure reducing valve is provided between the first flow meter and the ammonia decomposer. The opposite end of the first flow meter of the ammonia decomposer is connected to the intake valve of the internal combustion engine. A second flow meter is provided between the ammonia decomposer and the intake valve. A catalyst is provided in the ammonia decomposer, and the catalyst includes one or more of vanadium, ruthenium, rhodium, nickel, or platinum. The control method includes: 1) Ammonia supply and decomposition: Control the ammonia gas in the ammonia cylinder to enter the ammonia decomposer and undergo catalytic decomposition into ammonia and hydrogen; 2) Intake: Open the intake valve of the internal combustion engine body, close the exhaust valve of the internal combustion engine body, and the gas in the ammonia decomposer enters the internal combustion engine body; 3) Ignition: The ignition device ignites the ignition. 4) Exhaust: Controls the opening of the exhaust valve of the internal combustion engine body and the closing of the intake valve of the internal combustion engine body; The total flow rate of ammonia gas supplied by the ammonia cylinder is controlled to be 20~22.5L / min, the decomposition rate of ammonia gas in the ammonia decomposer is controlled to be 50~55%, and the equivalence ratio is controlled to be 1.10~1.

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2. The control method for an ammonia internal combustion engine system according to claim 1, characterized in that, The total flow rate of ammonia gas supplied by the ammonia cylinder is controlled at 22.5 L / min, the decomposition rate of ammonia gas in the ammonia decomposer is controlled at 50%, and the equivalent ratio is controlled at 1.

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3. The control method for an ammonia internal combustion engine system according to claim 1, characterized in that, The ammonia internal combustion engine system also includes a turbocharger.

4. The control method for an ammonia internal combustion engine system according to claim 1, characterized in that, The ammonia internal combustion engine system also includes an exhaust gas recirculator, which is used to recover the discharged exhaust gas and provide heat to the ammonia decomposer.

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