A combustion system and control method applicable to a large-bore ammonia-diesel engine

Abstract

The present invention discloses a combustion system applicable to a large-bore ammonia-diesel engine, which includes an engine, a pre-chamber subsystem, a fuel supply subsystem, and an electronic control subsystem; the interior of the pre-chamber main body of the pre-chamber subsystem is of a plow-shaped structure, and a high-pressure double direct injection injector is installed on its upper left side; the fuel supply subsystem includes an ammonia tank, a diesel fuel tank, and an intake port ammonia injector. Two ammonia supply pipelines of the ammonia tank, one is connected to the liquid ammonia channel of the high-pressure double direct injection injector; the other is connected to the intake port ammonia injector; the diesel fuel pipeline is connected to the diesel fuel channel of the high-pressure double direct injection injector; the electronic control subsystem includes a temperature sensor, a glow plug, a high-pressure double direct injection injector, and an intake port ammonia injector, all of which are connected to the ECU unit. The ECU unit adjusts the injection strategy of the intake port ammonia injector according to the engine throttle opening; controls the liquid ammonia and diesel injection strategies of the high-pressure double direct injection injector and the heating switch of the glow plug according to the pre-chamber temperature to regulate the temperature and combustion mode of the pre-chamber.

Description

Technical Field

[0001] The present invention relates to an internal combustion engine combustion system in the field of thermal energy and power engineering, and particularly to a combustion system and control method suitable for a large-bore ammonia-diesel engine. Background Art

[0002] Internal combustion engines are the most widely used leading power equipment in the national economy and national defense construction. They consume more than 60% of the world's petroleum and emit 25% of the global carbon emissions, making them one of the main sources of air pollution. To meet the requirements of energy conservation and carbon reduction, zero-carbon fuels such as green ammonia and green hydrogen have gradually attracted the attention of academia and industry. Compared with hydrogen, ammonia has the advantages of high volumetric energy density, high hydrogen storage density, and convenient storage and transportation. However, ammonia has problems such as difficult ignition and slow flame propagation speed, which are particularly prominent in large-bore engines. When a large-bore engine uses a spark plug for ignition, there are serious afterburning problems caused by slow combustion speed and long flame propagation distance. When using a micro-ignition ignition method, there are problems with poor wide-operating-condition adaptability, and the combustion mode using dual fuels also leads to high carbon emissions. Pre-chamber jet ignition can effectively ignite ammonia fuel in the main combustion chamber with a small amount of fuel. For small-bore engines (bore diameter < 100 mm), most existing pre-chambers have good ignition effects; but for large-bore engines (bore diameter > 150 mm), they have higher requirements for the length of the jet flame and a farther jet flame propagation distance. It is necessary to organize stable multi-beam extremely long jet flames to quickly ignite the end mixed gas, so as to achieve stable, efficient and clean combustion of large-bore engines. Summary of the Invention

[0003] In view of the above-mentioned prior art, the present invention provides a combustion system and control method suitable for a large-bore ammonia-diesel engine, which uses the diesel spray wall-impingement cooling effect to extend the ignition delay period. During the long ignition delay period, a large amount of evaporated mixed gas is formed by diesel in the pre-chamber, creating a combustion mode mainly based on premixed combustion and controllable knocking, greatly increasing the pressure difference between the pre-chamber and the main combustion chamber, forming a turbulent jet flame with an extremely long flame length and an extremely high flame speed, and meeting the requirements of stable, efficient combustion of large-bore engines.

[0004] To solve the above technical problems, a combustion system suitable for a large-bore ammonia-diesel engine proposed by the present invention includes an engine, a pre-chamber subsystem, a fuel supply subsystem, and an electronic control subsystem;

[0005] The pre - combustion chamber subsystem includes a pre - combustion chamber main body. Inside the pre - combustion chamber main body is a plow - shaped pre - combustion chamber cavity. A communication cavity leading to the main combustion chamber of the engine is provided on the lower right side of the pre - combustion chamber cavity. At the upper end of the pre - combustion chamber main body leading to the main combustion chamber of the engine, a high - pressure dual - direct - injection injector, a glow plug, and a temperature sensor are installed side by side from left to right in sequence. The high - pressure dual - direct - injection injector and the glow plug both vertically extend into the pre - combustion chamber cavity. The high - pressure dual - direct - injection injector includes a main body, and a diesel channel and an ammonia channel are provided on the main body.

[0006] The fuel supply subsystem includes an ammonia tank, a diesel tank, and an intake - port ammonia injector. The nozzle of the intake - port ammonia injector extends into the intake port of the engine. The ammonia tank is provided with two ammonia supply pipelines. An ammonia booster pump is provided on one of the ammonia supply pipelines. The outlet of the ammonia booster pump is connected to the inlet of the ammonia channel of the high - pressure dual - direct - injection injector. The ammonia booster pump boosts the ammonia and transports it to the high - pressure dual - direct - injection injector. The other ammonia supply pipeline is connected to the intake - port ammonia injector. A diesel booster pump is provided on the diesel pipeline of the diesel tank. The outlet of the diesel booster pump is connected to the inlet of the diesel channel of the high - pressure dual - direct - injection injector. The diesel booster pump boosts the diesel and transports it to the high - pressure dual - direct - injection injector.

[0007] The electronic control subsystem includes an ECU unit. The temperature sensor, the glow plug, the high - pressure dual - direct - injection injector, and the intake - port ammonia injector are all connected to the ECU unit.

[0008] Furthermore, for the combustion system applicable to an ammonia - diesel large - bore engine of the present invention, the diesel channel and the ammonia channel in the high - pressure dual - direct - injection injector are two independent fuel supply pipelines.

[0009] At the same time, the present invention also provides a control method for a combustion system applicable to an ammonia - diesel large - bore engine, including: the ECU unit adjusts the injection strategy of the intake - port ammonia injector according to the engine throttle opening, and is responsible for supplying gaseous ammonia fuel to the main combustion chamber of the engine; the temperature sensor is responsible for detecting the temperature of the pre - combustion chamber, and the glow plug is responsible for heating the combustible mixture in the pre - combustion chamber; the ECU unit controls the ammonia injection amount of the high - pressure dual - direct - injection injector and the heating switch of the glow plug according to the pre - combustion chamber temperature, thereby regulating the temperature of the pre - combustion chamber to ensure that the mixture in the pre - combustion chamber can stably ignite and avoid the ablation of the injector; the high - pressure dual - direct - injection injector independently injects liquid ammonia and diesel into the pre - combustion chamber. The ECU unit affects the oil - film thickness, fuel reactivity, and pre - combustion chamber temperature in the pre - combustion chamber by controlling the injection strategy of the high - pressure dual - direct - injection injector, and then regulates the diesel ignition delay period to ensure pre - mixed combustion in the pre - combustion chamber and form a controllable weak - detonation combustion mode.

[0010] Furthermore, the injection strategy of the high-pressure dual-direct injection injector includes: when the engine is warming up and running normally, controlling the high-pressure dual-direct injection injector to inject liquid ammonia first and then diesel; when starting cold, controlling the high-pressure dual-direct injection injector to inject only diesel; wherein, during the warm-up stage, controlling the high-pressure dual-direct injection injector to inject liquid ammonia with an energy ratio of 10% - 30% and diesel with an energy ratio of 70% - 90%; when running normally, controlling the high-pressure dual-direct injection injector to inject liquid ammonia with an energy ratio of 50% - 70% and diesel with an energy ratio of 30% - 50%.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0012] (1) The combustion system of the present invention utilizes the diesel spray wall impingement cooling effect to extend the ignition delay period. During the long ignition delay period, a large amount of evaporated and mixed gas is formed by diesel in the pre-combustion chamber, creating a combustion mode mainly based on premixed combustion and controllable detonation, greatly increasing the pressure difference between the pre-combustion chamber and the main combustion chamber, and forming a turbulent jet flame with an extremely long flame length and an extremely high flame speed. Specifically, a plow-shaped pre-combustion chamber is adopted in combination with the swirl during the compression process to achieve large-area fuel spray wall impingement, forming a large-area oil film, and liquid ammonia is used to regulate the fuel activity and the temperature of the pre-combustion chamber. The three cooperate with each other to ensure premixed combustion in the pre-combustion chamber, realizing a controllable weak detonation combustion mode, resulting in a very high pressure difference between the pre-combustion chamber and the main combustion chamber, and then forming a jet flame with a longer flame length and a higher flame speed.

[0013] (2) The combustion system of the present invention utilizes the characteristic of liquid ammonia vaporization endotherm to cool the pre-combustion chamber, and an electric heating plug is used to heat the combustible mixture in the pre-combustion chamber. The two cooperate to effectively regulate the temperature of the pre-combustion chamber, control the length of the diesel ignition delay period, and solve the problems of pre-combustion chamber injector ablation and difficult cold start ignition. Description of the Drawings

[0014] Figure 1 is a schematic diagram of the composition of the combustion system of the present invention;

[0015] Figure 2 is Figure 1 a schematic diagram of the pre-combustion chamber subsystem 2 shown in;

[0016] Figure 3 is Figure 1 a schematic diagram of the internal structure of the high-pressure dual-direct injection injector 8 shown in.

[0017] In the figure:

[0018] 1 - Engine 2 - Pre-combustion chamber subsystem 3 - Fuel supply subsystem

[0019] 4 - Electronic control subsystem 5 - Pre-combustion chamber main body 6 - Temperature sensor

[0020] 7 - Glow plug 8 - High - pressure double - direct - injection injector 801 - Main body

[0021] 802 - Diesel channel 803 - Liquid ammonia channel 9 - Pre - combustion chamber inner cavity

[0022] 10 - Ammonia tank 11 - Diesel fuel tank 12 - Ammonia booster pump

[0023] 13 - Diesel booster pump 14 - Ammonia supply pipeline 15 - Diesel pipeline

[0024] 16 - Inlet - passage ammonia injector 17 - ECU unit 18 - Connecting cavity Specific implementation mode

[0025] The following further describes the present invention in conjunction with the accompanying drawings and specific embodiments, but the following embodiments are by no means any limitation to the present invention.

[0026] A combustion system applicable to an ammonia - diesel large - bore engine proposed by the present invention includes an engine 1, a pre - combustion chamber subsystem 2, a fuel supply subsystem 3, and an electronic control subsystem 4; as Figure 1 shown.

[0027] As Figure 2 and Figure 3 shown, the pre - combustion chamber subsystem includes a pre - combustion chamber main body 5. The inner part of the pre - combustion chamber main body 5 is a plow - shaped pre - combustion chamber inner cavity 9. A connecting cavity 18 leading to the main combustion chamber of the engine is provided on the lower right side of the pre - combustion chamber inner cavity 9. At the upper end of the pre - combustion chamber main body 5 leading to the main combustion chamber of the engine, a high - pressure double - direct - injection injector 8, a glow plug 7, and a temperature sensor 6 are sequentially installed side by side from left to right. Both the high - pressure double - direct - injection injector 8 and the glow plug 7 vertically extend into the pre - combustion chamber inner cavity 9. In the present invention, the high - pressure double - direct - injection injector 8 is installed on the upper left side of the pre - combustion chamber inner cavity 9, and the connecting cavity 18 between the pre - combustion chamber inner cavity 9 and the pre - combustion chamber injection hole is located on the lower right side of the pre - combustion chamber inner cavity. This design ensures that a strong vortex is formed in the pre - combustion chamber during the compression process. After diesel and liquid ammonia are injected into the pre - combustion chamber inner cavity 9, fuel impingement on the wall occurs, forming a large - area oil film. The temperature sensor 6 is responsible for detecting the pre - combustion chamber temperature, and the glow plug 7 is responsible for heating the combustible mixture in the pre - combustion chamber. The ECU controls the liquid ammonia injection amount and the heating switch of the glow plug 7 according to the pre - combustion chamber temperature. The two are used in cooperation to regulate the temperature of the pre - combustion chamber, ensuring that the mixture in the pre - combustion chamber can ignite stably and avoid the ablation of the injector. Figure 3It is a schematic diagram of the internal pipeline of the high-pressure dual-direct injection injector in the present invention. The high-pressure dual-direct injection injector 8 includes a main body 801, and a diesel channel 802 and an ammonia channel 803 are provided on the main body 801. The diesel channel 802 and the ammonia channel 803 in the high-pressure dual-direct injection injector are two independent fuel supply pipelines. Diesel is transported to the pre-chamber through the diesel channel 802 of the high-pressure dual-direct injection injector, and ammonia is transported to the pre-chamber through the ammonia channel 803 of the high-pressure dual-direct injection injector. The two fuel delivery pipelines have no interference and blending inside the injector and are two independent fuel supply pipelines.

[0028] As Figure 1 shown, the fuel supply subsystem includes an ammonia tank 10, a diesel tank 11, and an intake port ammonia injector 16. The nozzle of the intake port ammonia injector 16 extends into the intake port of the engine 1. The ammonia tank 10 is provided with two ammonia supply pipelines 14. An ammonia booster pump 12 is provided on one of the ammonia supply pipelines. The outlet of the ammonia booster pump 12 is connected to the inlet of the ammonia channel 803 of the high-pressure dual-direct injection injector 8. The ammonia booster pump 12 boosts the ammonia and transports it to the high-pressure dual-direct injection injector 8 to supply liquid ammonia fuel to the pre-chamber. Since the ammonia fuel pressure required by the intake port ammonia injector 16 is relatively low and the pressure of the ammonia tank is sufficient to meet the requirements of the injector, the other ammonia supply pipeline is directly connected to the intake port ammonia injector 16 to supply gaseous ammonia fuel to the main combustion chamber using the pressure of the ammonia tank 10. A diesel booster pump 13 is provided on the diesel pipeline 15 of the diesel tank 11. The outlet of the diesel booster pump 13 is connected to the inlet of the diesel channel 802 of the high-pressure dual-direct injection injector 8. The diesel booster pump 13 boosts the diesel and transports it to the high-pressure dual-direct injection injector 8, which is responsible for providing high-pressure diesel for the pre-chamber.

[0029] As Figure 1As shown, the electronic control subsystem includes an ECU unit 17, and the temperature sensor 6, glow plug 7, high-pressure dual direct injection injector 8, and intake port ammonia injector 16 are all connected to the ECU unit 17. The ECU unit 17 adjusts the injection strategy of the intake port ammonia injector 16 according to the throttle opening of the engine 1, and is responsible for supplying gaseous ammonia fuel to the main combustion chamber of the engine; the temperature sensor 6 is responsible for detecting the pre-combustion chamber temperature, and the glow plug 7 is responsible for heating the combustible mixture in the pre-combustion chamber; the ECU unit 17 controls the liquid ammonia injection amount of the high-pressure dual direct injection injector 8 and the heating switch of the glow plug 7 according to the pre-combustion chamber temperature. The two are used in combination to regulate the temperature of the pre-combustion chamber, ensuring that the mixture in the pre-combustion chamber can stably ignite and avoid the ablation of the injector. The high-pressure dual direct injection injector 8 independently injects liquid ammonia and diesel into the pre-combustion chamber. The ECU unit 17 affects the oil film thickness, fuel activity, and pre-combustion chamber temperature in the pre-combustion chamber by controlling the injection strategy of the high-pressure dual direct injection injector 8, thereby regulating the diesel ignition delay period, ensuring pre-mixed combustion in the pre-combustion chamber, and forming a controllable weak detonation combustion mode. That is, when the ECU unit 17 controls both the engine warm-up and normal operation, the high-pressure dual direct injection injector first injects liquid ammonia and then injects diesel. During cold start, only diesel is injected. During the warm-up stage, liquid ammonia with an energy ratio of 10% - 30% and diesel with an energy ratio of 70% - 90% are injected. During normal operation, liquid ammonia with an energy ratio of 50% - 70% and diesel with an energy ratio of 30% - 50% are injected, ensuring that the pre-combustion chamber is always in a pre-mixed combustion state, achieving a controllable weak detonation combustion mode, and further forming a high-speed jet flame with a longer flame length. The specific operation process is as follows:

[0030] Step 1: The ECU unit 17 adjusts the injection strategy of the intake port ammonia injector 16 according to the throttle opening of the engine, and provides gaseous ammonia fuel for the main combustion chamber.

[0031] Step 2: The temperature sensor 6 detects the pre-combustion chamber temperature. When the pre-combustion chamber temperature is too low (during cold start), the ECU unit 17 controls the glow plug 7 to start heating, quickly increasing the temperature of the combustible mixture in the pre-combustion chamber. The ECU unit 17 controls the high-pressure dual direct injection injector 8 to only inject diesel. The injection timing is 20℃A - 30℃A before top dead center, and the injection amount is relatively large, ensuring that spray liquid phase wall collision occurs in the pre-combustion chamber. The large-area oil film results in a longer ignition delay period for diesel. Pre-mixed combustion mainly occurs in the pre-combustion chamber, and a violent weak detonation phenomenon occurs. The high pressure difference between the pre-combustion chamber and the main combustion chamber pushes the jet flame in the pre-combustion chamber into the main combustion chamber, and the jet flame with a longer flame length and higher flame speed ignites the combustible mixture in the main combustion chamber.

[0032] Step 3: When the cold start phase ends and the temperature of the pre - combustion chamber is relatively low (warm - up phase), the ECU unit 17 controls the glow plug 7 to continue heating, continuously increasing the temperature of the combustible mixture in the pre - combustion chamber. The ECU unit 17 controls the high - pressure dual - direct - injection injector to inject liquid ammonia with an energy ratio of 10% - 30% and diesel with an energy ratio of 70% - 90%. First, the liquid ammonia is injected, and then the diesel is injected. With the cooperation of the plow - shaped structure in the inner cavity of the pre - combustion chamber, large - area fuel wall - impingement occurs in the pre - combustion chamber. At this time, the liquid ammonia mainly plays the role of reducing the combustion activity in the pre - combustion chamber and prolonging the ignition delay period of diesel. The amount of liquid ammonia is small, and its function of vaporizing and absorbing heat to cool the pre - combustion chamber is weak. Although the temperature of the pre - combustion chamber increases, the addition of low - activity ammonia fuel still results in a relatively long ignition delay period of diesel, ensuring that the pre - combustion chamber is mainly in the premixed combustion mode, controlling weak detonation combustion in the pre - combustion chamber, and forming a high - pressure jet flame in the pre - combustion chamber that sprays into the main combustion chamber to ignite the combustible mixture in the main combustion chamber.

[0033] Step 4: When the warm - up phase ends and the engine is operating normally, the temperature of the pre - combustion chamber is relatively high at this time. The ECU unit 17 turns off the heating switch of the glow plug 7 and stops heating the combustible mixture in the pre - combustion chamber. The ECU unit 17 controls the high - pressure dual - direct - injection injector 8 to inject liquid ammonia with an energy ratio of 50% - 70% and diesel with an energy ratio of 30% - 50%. First, the liquid ammonia is injected in advance, and then the diesel is injected. The liquid ammonia and diesel undergo large - area fuel wall - impingement in the inner cavity 9 of the plow - shaped pre - combustion chamber. The liquid ammonia can effectively reduce the temperature of the pre - combustion chamber and avoid injector ablation. By using the multiple effects of fuel wall - impingement, controlling the temperature of the pre - combustion chamber, and reducing fuel activity to prolong the ignition delay period of diesel, it is ensured that the mixture in the pre - combustion chamber continues to be in the premixed combustion mode, achieving weak detonation combustion in the pre - combustion chamber, and continuously forming a strong high - speed jet flame in the pre - combustion chamber to ignite the combustible mixture in the main combustion chamber.

[0034] In summary, the present invention is a combustion system and control method for a large - bore ammonia - diesel engine. It prolongs the fuel ignition delay period by forming a large - area oil film through fuel wall - impingement, controlling fuel activity, and the temperature of the pre - combustion chamber, ensuring that the pre - combustion chamber is mainly in the premixed combustion mode and forming a controllable weak detonation combustion mode. By using the extremely high pressure difference between the pre - combustion chamber and the main combustion chamber to form a violent jet flame, the extremely long jet flame length and extremely high jet flame speed can effectively ignite the combustible mixture in the large - bore main combustion chamber.

[0035] Although the present invention has been described above in conjunction with the accompanying drawings, the present invention is not limited to the above - mentioned specific embodiments. The above - mentioned specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many variations without departing from the purpose of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A combustion system applicable to an ammonia-diesel large-bore engine, comprising an engine (1), a pre-chamber subsystem (2), a fuel supply subsystem (3), and an electronic control subsystem (4); The pre-chamber subsystem includes a pre-chamber main body (5). The interior of the pre-chamber main body (5) is a plow-shaped pre-chamber cavity (9). A communication cavity (18) leading to the main combustion chamber of the engine is provided on the lower right side of the pre-chamber cavity (9), leading to the main combustion chamber of the engine. At the upper end of the pre-chamber main body (5), a high-pressure dual-direct injection injector (8), a glow plug (7), and a temperature sensor (6) are sequentially installed side by side from left to right. The high-pressure dual-direct injection injector (8) and the glow plug (7) both vertically extend into the pre-chamber cavity (9). The high-pressure dual-direct injection injector (8) includes a main body (801), and a diesel channel (802) and an ammonia channel (803) are provided on the main body (801); The fuel supply subsystem includes an ammonia tank (10), a diesel tank (11), and an intake port ammonia injector (16). The nozzle of the intake port ammonia injector (16) extends into the intake port of the engine (1). The ammonia tank (10) is provided with two ammonia supply pipelines. An ammonia booster pump (12) is provided on one of the ammonia supply pipelines. The outlet of the ammonia booster pump (12) is connected to the inlet of the ammonia channel (803) of the high-pressure dual-direct injection injector (8). The ammonia booster pump (12) boosts the ammonia and transports it to the high-pressure dual-direct injection injector (8). The other ammonia supply pipeline is connected to the intake port ammonia injector (16). A diesel booster pump (13) is provided on the diesel pipeline (15) of the diesel tank (11). The outlet of the diesel booster pump (13) is connected to the inlet of the diesel channel (802) of the high-pressure dual-direct injection injector (8). The diesel booster pump (13) boosts the diesel and transports it to the high-pressure dual-direct injection injector (8); The electronic control subsystem includes an ECU unit (17). The temperature sensor (6), the glow plug (7), the high-pressure dual-direct injection injector (8), and the intake port ammonia injector (16) are all connected to the ECU unit (17).

2. The combustion system applicable to an ammonia-diesel large-bore engine according to claim 1, wherein, The diesel channel (802) and the liquid ammonia channel (803) in the high-pressure dual direct injection injector are two independent fuel supply pipelines.

3. A control method for a combustion system applicable to an ammonia-diesel large-bore engine, characterized in that, Adopt the combustion system described in claim 1 or 2; The ECU unit (17) adjusts the injection strategy of the intake ammonia injector (16) according to the throttle opening of the engine (1), and is responsible for supplying gaseous ammonia fuel to the main combustion chamber of the engine; The temperature sensor (6) is responsible for detecting the pre-chamber temperature, and the glow plug (7) is responsible for heating the combustible mixture in the pre-chamber; the ECU unit (17) controls the liquid ammonia injection amount of the high-pressure dual direct injection injector (8) and the heating switch of the glow plug (7) according to the pre-chamber temperature, so as to regulate the temperature of the pre-chamber to ensure that the mixture in the pre-chamber can ignite stably and avoid ablation of the injector; The high-pressure dual direct injection injector (8) independently injects liquid ammonia and diesel into the pre-chamber. The ECU unit (17) affects the oil film thickness, fuel activity and pre-chamber temperature in the pre-chamber by controlling the injection strategy of the high-pressure dual direct injection injector (8), and then regulates the diesel ignition delay period to ensure pre-mixed combustion in the pre-chamber and form a controllable weak detonation combustion mode; The injection strategy of the high-pressure dual direct injection injector (8) includes: When the engine is cold started, control the high-pressure dual direct injection injector (8) to only inject diesel; When the engine is warming up and running normally, control the high-pressure dual direct injection injector (8) to inject liquid ammonia first and then diesel; among them, during the engine warming-up stage, control the high-pressure dual direct injection injector (8) to inject liquid ammonia with an energy ratio of 10% - 30% and diesel with an energy ratio of 70% - 90%; when the engine is running normally, control the high-pressure dual direct injection injector (8) to inject liquid ammonia with an energy ratio of 50% - 70% and diesel with an energy ratio of 30% - 50%.

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