An ammonia-diesel dual fuel engine combustion control system and method

Abstract

The application provides an ammonia-diesel dual-fuel engine combustion control system and method, and relates to the technical field of engines.The control system comprises an engine, an ammonia supply device, a control device and a diesel supply device, the cylinder head of the engine is provided with a diesel electrically-controlled nozzle, and the intake valve of the engine is communicated with an air inlet pipe.The ammonia supply device comprises an ammonia tank, an ammonia pipeline and an ammonia nozzle, the control device is used for adjusting the energy replacement rate of ammonia by controlling the ammonia fuel injection amount of the ammonia nozzle and the diesel injection amount of the diesel electrically-controlled nozzle, and controlling the diesel electrically-controlled nozzle to adopt different injection modes under different ammonia energy replacement rates.The control strategy of the overall excess air coefficient being 1.0 is adopted to reduce the nitrogen oxide and particulate matter emissions in tail gas, different injection modes are adopted according to different ammonia energy replacement rates, the optimal in-cylinder combustion effect is achieved under different ammonia energy replacement rates, the power of the engine is improved, the amount of nitrogen oxide and particulate matter emissions is reduced, and the engine realizes high-efficiency and stable combustion.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engine, in particular to a combustion control system and method of ammonia-diesel dual fuel engine. BACKGROUND

[0002] In recent years, the world has paid more and more attention to the research and application of ammonia fuel. Due to the high natural temperature, large ignition energy and slow combustion speed of ammonia fuel, it is difficult to use it as a single fuel in an engine. Therefore, it is usually mixed with high activity fuel in an engine to expand the application conditions of ammonia fuel. A large amount of research has been conducted on the mixed combustion of ammonia and diesel. At present, the ammonia fuel supply mode of ammonia-diesel dual fuel engine on the engine is divided into low-pressure gaseous ammonia injection in the intake port and high-pressure liquid ammonia injection in the cylinder. If low-pressure gaseous ammonia injection is used, it belongs to premixed combustion, and ammonia and air are mixed uniformly, so that ammonia combustion is sufficient. However, due to the occupation of a part of air volume by gaseous ammonia in the intake port, the pump loss will increase when the ammonia energy replacement rate is high, which is not conducive to the efficient combustion of the engine. If high-pressure liquid ammonia injection in the cylinder is used, it belongs to diffusion combustion, the injection phase can be accurately controlled, and it does not occupy the air volume in the intake port, so it is easier to realize high replacement rate combustion of ammonia. However, due to the large latent heat of vaporization of liquid ammonia, the vaporization of liquid ammonia injected into the cylinder will cause a sharp decrease in cylinder temperature, which is not conducive to flame propagation and mixed gas combustion in the cylinder.

[0003] On the other hand, generally, when the overall excess air ratio of a pure diesel engine is 1.0, the combustion is rough, the engine shakes greatly, the thermal efficiency is low, and the phenomenon of "black smoke" appears. Increasing the oxygen content in a lean-burn way can reduce the emission of soot and particulate matter, but cannot avoid the generation of soot and particulate matter under high load. In the ammonia-diesel dual fuel combustion process, the zero-carbon property of ammonia fuel will not increase the emission of soot, so the organization strategy of the mixed gas can be different from that of a diesel engine. In order to solve the above problems, it is necessary to provide a control method of ammonia-diesel dual fuel engine. SUMMARY

[0004] The present application provides a kind of ammonia-diesel dual fuel engine combustion control system, to solve the problems of low efficiency of engine, high nitrogen oxides and particulate matter emissions in existing technology.

[0005] The present application provides a kind of ammonia-diesel dual fuel engine combustion control system, comprising:

[0006] An engine, the cylinder head of the engine is provided with a diesel electronic control nozzle, the intake valve of the engine is communicated with the intake pipe, and the high-pressure oil rail pressure of the engine is greater than or equal to 1400 bar;

[0007] The ammonia supply device comprises an ammonia bottle, an ammonia pipeline and a gaseous ammonia nozzle, the diesel electric control nozzle is communicated with the outlet of the ammonia bottle through the ammonia pipeline, the gaseous ammonia nozzle is arranged on the air inlet pipe, the gaseous ammonia nozzle is used for spraying ammonia into the air inlet pipe, the spraying pressure of the gaseous ammonia nozzle is greater than or equal to 5 bar and less than or equal to 7 bar;

[0008] A control device is electrically connected with the gaseous ammonia nozzle and the diesel electric control nozzle, and is used for adjusting the energy replacement rate of ammonia by controlling the ammonia spraying amount of the gaseous ammonia nozzle and the diesel spraying amount of the diesel electric control nozzle, and controlling the diesel electric control nozzle to adopt different spraying modes under different ammonia energy replacement rates.

[0009] A diesel supply device is communicated with the diesel electric control nozzle, and is used for conveying diesel to the diesel electric control nozzle.

[0010] According to the ammonia-diesel dual fuel engine combustion control system provided by the application, the ammonia supply device further comprises:

[0011] A first mass flow meter is arranged on the ammonia pipeline, and is used for detecting the ammonia flow and mass output by the ammonia bottle.

[0012] According to the ammonia-diesel dual fuel engine combustion control system provided by the application, the ammonia supply device further comprises:

[0013] A pressure reducing valve is arranged on the outlet of the ammonia bottle, and is used for reducing the ammonia pressure output by the outlet of the ammonia bottle.

[0014] According to the ammonia-diesel dual fuel engine combustion control system provided by the application, the ammonia supply device further comprises:

[0015] A first display device is electrically connected with the first mass flow meter, and is used for displaying the ammonia flow and mass output by the ammonia bottle.

[0016] According to the ammonia-diesel dual fuel engine combustion control system provided by the application, the air inlet pipe is provided with a pressure regulating valve and a pressure stabilizing tank, the pressure regulating valve is used for regulating the air inlet pressure of the air inlet pipe, the pressure regulating valve is electrically connected with the first display device and the control device, and the first display device is further used for displaying the air inlet pressure of the air inlet pipe; the pressure stabilizing tank is used for maintaining the pressure in the air inlet pipe stable, and the pressure stabilizing tank is electrically connected with the control device.

[0017] According to the ammonia-diesel dual fuel engine combustion control system provided by the application, the ammonia supply device further comprises:

[0018] A power dynamometer is connected to the output shaft of the engine.

[0019] The combustion control system of the ammonia-diesel dual fuel engine provided by the application comprises a storage tank, an oil delivery pipe, a filter and a high-pressure oil pump.

[0020] The filter is arranged at the oil inlet of the oil delivery pipe, and the high-pressure oil pump is connected in series to the oil delivery pipe.

[0021] The combustion control system of the ammonia-diesel dual fuel engine provided by the application further comprises a liquid ammonia nozzle and an electric heating plug arranged on the cylinder head of the engine.

[0022] The liquid ammonia nozzle is connected to the outlet of the ammonia tank through a liquid ammonia pipeline, and the liquid ammonia pipeline is provided with a booster pump and a second mass flow meter.

[0023] (1)

[0024] Wherein, is the theoretical air-fuel ratio of the ammonia-diesel mixed gas, is calculated by the following formula (2).

[0025] (2)

[0026] Wherein, is the theoretical air-fuel ratio of pure diesel, is the theoretical air-fuel ratio of pure ammonia, is the mass flow of the ammonia fuel, is the flow of diesel;

[0027] is the actual air-fuel ratio of the ammonia-diesel mixed gas, and if low-pressure gaseous ammonia injection is used, is calculated by the following formula (3).

[0028] (3)

[0029] If high-pressure in-cylinder liquid ammonia injection is used, is calculated by the following formula (4).

[0030] (4)

[0031] wherein, is the air flow rate in the intake pipe.

[0032] The present application also provides an ammonia-diesel dual fuel engine combustion control method, which is based on the ammonia-diesel dual fuel engine combustion control system of any one of the above, the engine adopts a control strategy with a global excess air ratio of 1.0, and the compression ratio of the engine is 18-23, so as to reduce the nitrogen oxide and particulate matter emissions in the exhaust gas, and the control method comprises the following steps:

[0033] When the ammonia replacement rate is less than 30%, pre-injection is controlled to be performed on the diesel electric control nozzle at 10°-20°CA before the top dead center, and main injection is controlled to be performed on the diesel electric control nozzle at 2°-4°CA before the top dead center;

[0034] When the ammonia replacement rate is 30%-70%, pre-injection is controlled to be performed on the diesel electric control nozzle at 20°-60°CA before the top dead center, main injection is controlled to be performed on the diesel electric control nozzle at 2°-4°CA before the top dead center, and post-injection is controlled to be performed on the diesel electric control nozzle at 10°-40°CA before the top dead center;

[0035] When the ammonia replacement rate is 70%-100%, main injection is controlled to be performed on the diesel electric control nozzle at 0°-10°CA before the top dead center, and liquid ammonia injection is controlled to be performed on the liquid ammonia nozzle at 20°-300°CA before the top dead center.

[0036] The ammonia-diesel dual fuel engine combustion control system provided by the present application adopts different injection modes according to different ammonia energy replacement rates, achieves optimal in-cylinder combustion effect under different ammonia energy replacement rates, improves the power of the engine, reduces the amount of nitrogen oxide and particulate matter emissions, and realizes efficient and stable combustion of the engine. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the present application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort.

[0038] Figure 1 is a structural schematic diagram of the ammonia-diesel dual fuel engine combustion control system provided by the present application.

[0039] Figure 2 is a schematic diagram of the engine IMEP with different global excess air ratios provided by the present application.

[0040] Figure 3is a schematic diagram of the nitrogen oxide emission of the different overall excess air coefficients provided by the present application.

[0041] Figure 4 is a schematic diagram of the particulate emission when the overall excess air coefficient is 1.0 provided by the present application.

[0042] Figure 5 is a structural schematic diagram of the ammonia-diesel dual fuel engine combustion control system provided by another embodiment of the present application.

[0043] Reference signs:

[0044] 10, engine; 11, diesel electric control nozzle; 12, air intake pipe; 13, pressure regulating valve; 14, pressure stabilizing tank; 15, liquid ammonia nozzle; 16, electric heating plug; 17, liquid ammonia pipeline; 18, booster pump; 19, second mass flow meter; 20, ammonia supply device; 21, ammonia gas cylinder; 22, ammonia pipeline; 23, gaseous ammonia nozzle; 24, first mass flow meter; 30, control device; 40, diesel supply device; 41, oil storage tank; 42, oil delivery pipeline; 50, first display device; 60, electric dynamometer; 70, combustion analyzer; 71, emission analyzer; 72, engine particulate analyzer; 73, second display device. DETAILED DESCRIPTION

[0045] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below with reference to the drawings in the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0046] In the description of the embodiments of the present application, it should be noted that the orientations or positional relationships indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and are not intended to indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0047] In the description of the embodiments of the present application, it should be noted that unless specifically defined and limited otherwise, the terms "connected", "connected to", "connection" should be interpreted broadly, for example, can be fixed connection, can also be detachable connection, or integral connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0048] In the embodiments of the present application, unless specifically defined and limited otherwise, the first feature is "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature "above", "over" and "on" the second feature can be that the first feature is directly above or obliquely above the second feature, or only means that the first feature is higher in horizontal height than the second feature. The first feature "below", "under" and "under" the second feature can be that the first feature is directly below or obliquely below the second feature, or only means that the first feature is lower in horizontal height than the second feature.

[0049] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the present application and the features of the different embodiments or examples without contradiction.

[0050] The specific structure and working principle of the ammonia-diesel dual-fuel engine combustion control system of the present application are described below. Figures 1-5 The specific structure and working principle of the ammonia-diesel dual-fuel engine combustion control system of the present application are described below.

[0051] Figure 1 The structure diagram of the ammonia-diesel dual-fuel engine combustion control system provided by the present application is illustrated, as shown in Figure 1As shown, the ammonia-diesel dual fuel engine combustion control system comprises an engine 10, an ammonia supply device 20, a control device 30 and a diesel supply device 40, the cylinder head of the engine 10 is provided with a diesel electronic control nozzle 11, the intake valve of the engine 10 is communicated with an intake pipe 12, and the high-pressure oil rail pressure of the engine 10 is greater than or equal to 1400 bar. The ammonia supply device 20 comprises an ammonia bottle 21, an ammonia pipeline 22 and an ammonia nozzle 23, the diesel electronic control nozzle 11 is communicated with the outlet of the ammonia bottle 21 through the ammonia pipeline 22, the ammonia nozzle 23 is arranged on the intake pipe 12, the ammonia nozzle 23 is used for spraying ammonia into the intake pipe 12, the spraying pressure of the ammonia nozzle 23 is greater than or equal to 5 bar and less than or equal to 7 bar. The control device 30 is electrically connected with the ammonia nozzle 23 and the diesel electronic control nozzle 11, the control device 30 is used for adjusting the energy replacement rate of ammonia by controlling the ammonia spraying amount of the ammonia nozzle 23 and the diesel spraying amount of the diesel electronic control nozzle 11, and controlling the diesel electronic control nozzle 11 to adopt different spraying modes under different ammonia energy replacement rates. The diesel supply device 40 is communicated with the diesel electronic control nozzle 11, and the diesel supply device 40 is used for delivering diesel to the diesel electronic control nozzle 11.

[0052] The ammonia-diesel dual fuel engine combustion control system provided by the application adopts different spraying modes according to different ammonia energy replacement rates, achieves the optimal in-cylinder combustion effect under different ammonia energy replacement rates, improves the power of the engine 10, reduces the amount of nitrogen oxide and particulate matter emissions, and realizes high-efficiency, stable combustion of the engine 10.

[0053] In an embodiment of the application, the control device 30 is an ECU control unit, and of course, the specific type of the control device 30 is not limited to this, and other types of control devices 30 can also be used.

[0054] The ammonia nozzle 23 sprays ammonia into the intake pipe 12, and the spraying pressure is not less than 5 bar and less than or equal to 7 bar. Diesel is sprayed into the cylinder of the engine 10 by the diesel electronic control nozzle 11 in the way of in-cylinder direct injection, wherein the high-pressure oil rail pressure should be not less than 1400 bar to obtain a long penetration distance. According to the intake amount and the ammonia energy proportion, the control device 30 controls the ammonia spraying amount of the ammonia nozzle 23 and the diesel spraying amount of the diesel electronic control nozzle 11. According to the demand of the intake amount and power of the engine 10, the overall excess air ratio of the ammonia-diesel dual fuel is always maintained at 1.0, corresponding spraying strategies are adopted under different engine 10 working conditions, the optimal in-cylinder combustion effect is achieved, and high-efficiency, clean and stable combustion of the engine 10 is realized.

[0055] In one embodiment of the present application, the ammonia supply device 20 further comprises a first mass flow meter 24, which is arranged in the ammonia pipeline 22 and used to detect the flow rate and mass of ammonia output by the ammonia cylinder 21. The control device 30, the first mass flow meter 24, and the ammonia injection nozzle 23 cooperate to realize closed-loop control, thereby accurately controlling the ammonia injection amount.

[0056] In one embodiment of the present application, the ammonia supply device 20 further comprises a pressure reducing valve, which is arranged at the outlet of the ammonia cylinder 21 and used to reduce the ammonia pressure output by the outlet of the ammonia cylinder 21 to adapt to the combustion requirements of the engine 10. Since ammonia is stored in liquid form, the natural gasification speed of liquid ammonia is slow, and the pressure reducing valve plays a key role in this process, improving the gasification speed of ammonia and solving the fuel supply problem of the ammonia-diesel dual-fuel engine 10.

[0057] In one embodiment of the present application, the ammonia-diesel dual-fuel engine combustion control system further comprises a first display device 50, which is electrically connected to the first mass flow meter 24 and used to display the flow rate and mass of ammonia output by the ammonia cylinder 21. The first mass flow meter 24 is a high-precision measuring device that can measure the flow mass and volumetric flow rate of ammonia. The first display device 50 displays the flow rate and mass of ammonia output by the ammonia cylinder 21 in real time, which is crucial for monitoring the combustion efficiency of the engine 10 and ensuring the safe operation of the engine 10. The control device 30 can adjust the fuel supply, optimize the combustion process, and improve the combustion efficiency of the engine 10 based on these data.

[0058] In one embodiment of the present application, the intake pipe 12 is provided with a pressure regulating valve 13 and a pressure stabilizing tank 14. The pressure regulating valve 13 is used to adjust the intake pressure of the intake pipe 12, and is electrically connected to the first display device 50 and the control device 30. The first display device 50 is also used to display the intake pressure of the intake pipe 12, and the control device 30 can accurately control the intake amount of the intake pipe 12 by controlling the pressure regulating valve 13. The pressure stabilizing tank 14 is used to maintain the pressure in the intake pipe 12 stable, and is electrically connected to the control device 30. The pressure regulating valve 13 and the pressure stabilizing tank 14 work together, with the pressure regulating valve 13 responsible for adjusting the pressure as needed, and the pressure stabilizing tank 14 responsible for providing a buffer when the pressure fluctuates to maintain the pressure in the intake pipe 12 stable.

[0059] In one embodiment of the present application, the ammonia-diesel dual fuel engine combustion control system further comprises an electric dynamometer 60, the output shaft of the engine 10 is connected to the electric dynamometer 60, and the electric dynamometer 60 is electrically connected to the control device 30. The electric dynamometer 60 measures the mechanical energy output by the engine 10 and converts it into electrical energy for measurement. This energy conversion process enables the electric dynamometer 60 to accurately measure the power output of the engine 10. The electric dynamometer 60 measures and evaluates the performance of the engine 10 to optimize combustion efficiency and reduce emissions.

[0060] In one embodiment of the present application, the diesel fuel supply device 40 comprises a fuel tank 41 and a fuel delivery pipe 42, and the fuel tank 41 is connected to the diesel electronic fuel injector 11 through the fuel delivery pipe 42.

[0061] In one embodiment of the present application, the diesel fuel supply device 40 further comprises a filter and a high-pressure fuel pump. The filter is installed at the inlet of the fuel delivery pipe 42, and its main function is to filter impurities and water in the fuel. This is crucial for protecting precision components such as fuel pumps and injectors from wear and blockage. The high-pressure fuel pump is connected in series to the fuel delivery pipe 42. The function of the high-pressure fuel pump is to pressurize the low-pressure fuel that has been preliminarily filtered to a certain pressure, and to deliver the diesel fuel to the diesel electronic fuel injector 11 at a certain pressure, flow rate, and cleanliness. This is crucial for the stable combustion and performance of the ammonia-diesel dual fuel engine 10, because the injection of diesel fuel must be precisely synchronized with the injection of ammonia gas to achieve optimal combustion efficiency and minimal emissions.

[0062] In one embodiment of the present application, Figure 5 An example of the structure of the ammonia-diesel dual fuel engine combustion control system provided by another embodiment of the present application is shown in FIG. 2. Figure 5As shown, the cylinder head of the engine 10 is further provided with a liquid ammonia nozzle 15 and a glow plug 16, the liquid ammonia nozzle 15 is communicated with the outlet of the ammonia bottle 21 through a liquid ammonia pipeline 17, the liquid ammonia pipeline 17 is provided with a booster pump 18 and a second mass flow meter 19, the liquid ammonia nozzle 15 and the glow plug 16 are electrically connected with the control device 30, and the second mass flow meter 19 is electrically connected with the first display device 50. The second mass flow meter 19 is used for detecting the flow and mass of the liquid ammonia output by the ammonia bottle 21, the liquid ammonia nozzle 15 is used for spraying liquid ammonia to the surface of the glow plug 16, and the glow plug 16 is used for heating the liquid ammonia. At 70%~100% high replacement rate, the combustion of ammonia will be dominant, if the gaseous supply mode is used, the air volume of the intake pipe will be occupied, the pumping loss will be increased, and the engine thermal efficiency will be reduced, therefore, the liquid ammonia supply mode is used, the liquid ammonia is directly injected into the cylinder through the liquid ammonia pipeline 17 and the booster pump 18, and then through the liquid ammonia nozzle 15, and the injection pressure is 200~1000bar. The injection timing is adjusted at 20°CA~300°CA before the top dead center, because the latent heat of ammonia is large, the liquid ammonia entering the cylinder will cause the temperature in the cylinder to decrease sharply, therefore, the glow plug 16 is added to heat the liquid ammonia sprayed on the glow plug 16, so as to make up the heat absorbed by the vaporization of the liquid ammonia, increase the temperature in the cylinder, promote the full combustion of the ammonia fuel, and reduce the unburned ammonia emission. In order to improve the combustion efficiency of the ammonia fuel, the compression ratio of the engine must be a high compression ratio of 18~23.

[0063] In one embodiment of the present application, the diesel supply device 40 further comprises a combustion analyzer 70, an emission analyzer 71, an engine particle analyzer DMS500, and a second display device 73. The engine particle analyzer DMS500 is referred to as the engine particle analyzer 72 for short. The exhaust valve of the engine 10 is connected to the exhaust pipe. The combustion analyzer 70, the emission analyzer 71, and the engine particle analyzer 72 are all connected to the exhaust pipe. The combustion analyzer 70, the emission analyzer 71, and the engine particle analyzer 72 are all electrically connected to the second display device 73. The combustion analyzer 70 is used to measure and analyze various parameters during the combustion process of the engine 10, such as combustion efficiency, combustion stability, and combustion temperature. These parameters are crucial for optimizing the combustion process of the engine 10, improving combustion efficiency, and reducing emissions. By precisely controlling the combustion process, the generation of harmful emissions can be reduced, and the utilization of fuel can be improved. The emission analyzer 71 is used to measure and analyze the composition of the gases emitted by the engine 10, including but not limited to carbon dioxide, carbon monoxide, nitrogen oxides, and hydrocarbons. These data are very important for evaluating the environmental performance of the engine 10 and complying with emission standards. The emission analyzer 71 can help engineers understand the composition of emissions, so that appropriate measures can be taken to reduce the emission of pollutants. The engine particle analyzer 72 is used to measure particulate matter in the emissions of the engine 10. The engine particle analyzer 72 can measure particles ranging in size from 5 nanometers to 2.5 micrometers, providing real-time data on the size, number, and mass of particulate matter.

[0064] In one embodiment of the present application, during the operation of the engine 10, ammonia and diesel form an ammonia-diesel mixture inside the engine 10. The overall excess air ratio λ of the ammonia-diesel mixture can be calculated by the following formula (1):

[0065] (1)

[0066] wherein, is the theoretical air-fuel ratio of the ammonia-diesel mixture, can be calculated by the following formula (2):

[0067] (2)

[0068] wherein, is the theoretical air-fuel ratio of pure diesel, the value of is 14.5; is the theoretical air-fuel ratio of pure ammonia, the value of is 6.17; is the mass flow rate of ammonia fuel, is the flow rate of diesel;

[0069] is the actual air-fuel ratio of the ammonia-diesel mixture, if low-pressure gaseous ammonia injection is used The calculation can be performed by the following formula (3) ;

[0070] (3)

[0071] If high-pressure cylinder-injection of liquid ammonia is used, The calculation can be performed by the following formula (4) ;

[0072] (4)

[0073] wherein, is the air flow in the intake pipe.

[0074] When formula (3) is used to calculate the actual air-fuel ratio, since ammonia is injected in the intake pipe, a part of the air mass flow is occupied, and therefore in the calculation of the actual air-fuel ratio, the ammonia mass in the intake pipe needs to be subtracted.

[0075] The ammonia-diesel dual-fuel engine combustion control system provided by the application uses different injection modes according to different ammonia energy replacement rates, achieves optimal in-cylinder combustion effect under different ammonia energy replacement rates, improves the power of the engine 10, reduces the amount of nitrogen oxide and particulate matter emissions, and realizes efficient and stable combustion of the engine 10.

[0076] The application further provides an ammonia-diesel dual-fuel engine combustion control method, which is based on the ammonia-diesel dual-fuel engine combustion control system of any one of the above embodiments, the engine adopts a control strategy with an overall excess air ratio of 1.0, and the compression ratio of the engine is 18-23, so as to reduce the nitrogen oxide and particulate matter emissions in the exhaust gas, and the ammonia-diesel dual-fuel engine combustion control method comprises the following steps.

[0077] When the ammonia replacement rate is less than 30 %, pre-injection is controlled to be performed on the diesel electric control nozzle 11 at 10°-20°CA before the top dead center, and main injection is controlled to be performed on the diesel electric control nozzle 11 at 2°-4°CA before the top dead center;

[0078] It should be noted that when the ammonia replacement rate is less than 30 %, the diesel combustion proportion is large, pre-injection is controlled to be performed on the diesel electric control nozzle 11 at 10°-20°CA before the compression top dead center, the combustion heat of the diesel in this part increases the overall temperature in the engine cylinder, so that the diesel entering the cylinder through main injection (2°-4°CA before the top dead center) can be ignited faster, the proportion of diesel premixed combustion is reduced, the maximum pressure rise rate is reduced, and rough combustion is avoided.

[0079] When the ammonia replacement rate is between 30% and 70%, the diesel electric control nozzle 11 is controlled to perform pre-injection 20-60°CA before the top dead center, the diesel electric control nozzle 11 is controlled to perform main injection 2-4°CA before the top dead center, and the diesel electric control nozzle 11 is controlled to perform post-injection 10-40°CA after the top dead center;

[0080] It should be noted that when the ammonia replacement rate is between 30% and 70%, the pre-injection time can be further advanced to 20-60°CA before the top dead center. By advancing the pre-injection time, the heat atmosphere of the in-cylinder mixture is improved, thereby improving the ammonia combustion efficiency. At the same time, a post-injection (10-40°CA after the top dead center) is added to ignite the unburned ammonia gas near the cylinder wall, thereby reducing unburned ammonia emissions. The post-injection time should not be too late to reduce the impact on the thermal efficiency of the engine 10.

[0081] When the ammonia replacement rate is between 70% and 100%, the diesel electric control nozzle 11 is controlled to perform main injection 0-10°CA before the top dead center, and the liquid ammonia nozzle 15 is controlled to perform liquid ammonia injection 20-300°CA before the top dead center.

[0082] When the ammonia replacement rate is higher than 70%, the diesel injection amount is reduced, and the rough combustion phenomenon is weakened. Therefore, no diesel pre-injection is performed to improve the combustion isovolume and reduce excessive heat loss, thereby improving the combustion efficiency. The main injection at this time is performed in a low-temperature environment, and has a longer ignition delay period. Therefore, the main injection time needs to be appropriately relaxed to 0-10°CA before the compression top dead center.

[0083] Figure 2 A schematic diagram of the engine IMEP provided by the present application using different overall excess air ratios is shown, Figure 3 A schematic diagram of the nitrogen oxide emission provided by the present application using different overall excess air ratios is shown, Figure 4 A schematic diagram of the particulate matter emission provided by the present application when the overall excess air ratio is 1.0 is shown, Figures 2 to 4 As shown in the figure, the ammonia-diesel dual-fuel engine combustion control method of the present application controls the diesel injection amount according to the intake amount and the ammonia replacement rate, so that the overall excess air ratio is controlled to be 1.0. The control strategy using an overall excess air ratio of 1.0 can effectively reduce the nitrogen oxide and particulate matter emissions in the exhaust gas through combustion means, while improving the IMEP (Indicated mean effective pressure) of the engine 10.

[0084] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the same; and although the present application has been described in detail with reference to the foregoing embodiments, it should be appreciated by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features thereof can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An ammonia-diesel dual-fuel engine combustion control system, characterized in that: include: An engine (10), wherein a cylinder head of the engine (10) is provided with a diesel electronically controlled nozzle (11), an intake valve of the engine (10) is in communication with an intake pipe (12), and a high-pressure fuel rail pressure of the engine (10) is greater than or equal to 1400 bar; an ammonia supply device (20), comprising an ammonia cylinder (21), an ammonia pipeline (22), and an ammonia gas nozzle (23); the diesel electronically controlled nozzle (11) is connected to the outlet of the ammonia cylinder (21) via the ammonia pipeline (22); the ammonia gas nozzle (23) is arranged on the intake pipe (12); the ammonia gas nozzle (23) is used to inject ammonia gas into the intake pipe (12); and the injection pressure of the ammonia gas nozzle (23) is greater than or equal to 5 bar and less than or equal to 7 bar; a control device (30), the control device (30) being electrically connected to the gas ammonia nozzle (23) and the diesel electronically controlled nozzle (11), the control device (30) being used to adjust the energy substitution rate of ammonia by controlling the ammonia injection amount of the gas ammonia nozzle (23) and the diesel injection amount of the diesel electronically controlled nozzle (11), and controlling the diesel electronically controlled nozzle (11) to adopt different injection modes under different ammonia energy substitution rates; A diesel supply device (40) is connected to the diesel electronically controlled nozzle (11), and the diesel supply device (40) is used to deliver diesel to the diesel electronically controlled nozzle (11).

2. The ammonia-diesel dual-fuel engine combustion control system according to claim 1, characterized in that: The ammonia supply device (20) further includes: A first mass flow meter (24) is provided on the ammonia pipeline (22), and the first mass flow meter (24) is used to detect the flow rate and quality of ammonia outputted from the ammonia cylinder (21).

3. The ammonia-diesel dual-fuel engine combustion control system according to claim 2, characterized in that: The ammonia supply device (20) further includes: A pressure reducing valve is provided at the outlet of the ammonia cylinder (21), and is used to reduce the pressure of ammonia outputted from the outlet of the ammonia cylinder (21).

4. The ammonia-diesel dual-fuel engine combustion control system according to claim 2, characterized in that: Also includes: A first display device (50) is electrically connected to the first mass flow meter (24), and the first display device (50) is used to display the flow rate and mass of ammonia outputted from the ammonia cylinder (21).

5. The ammonia-diesel dual-fuel engine combustion control system according to claim 4, characterized in that: The intake pipe (12) is provided with a pressure regulating valve (13) and a pressure stabilizing tank (14). The pressure regulating valve (13) is used to regulate the intake pressure of the intake pipe (12). The pressure regulating valve (13) is electrically connected to the first display device (50) and the control device (30). The first display device (50) is also used to display the intake pressure of the intake pipe (12). The pressure stabilizing tank (14) is used to maintain the pressure in the intake pipe (12) stable. The pressure stabilizing tank (14) is electrically connected to the control device (30).

6. The ammonia-diesel dual-fuel engine combustion control system according to any one of claims 1 to 5, characterized in that: Also includes: An electric dynamometer (60) is connected to the output shaft of the engine (10).

7. The ammonia-diesel dual-fuel engine combustion control system according to any one of claims 1 to 5, characterized in that: The diesel supply device (40) comprises an oil storage tank (41), an oil delivery pipe (42), a filter and a high-pressure oil pump. The oil storage tank (41) is connected to the diesel electronically controlled nozzle (11) through the oil delivery pipe (42); the filter is arranged at the oil inlet of the oil delivery pipe (42), and the high-pressure oil pump is connected in series to the oil delivery pipe (42).

8. The ammonia-diesel dual-fuel engine combustion control system according to claim 4 or 5, characterized in that: The cylinder head of the engine (10) is further provided with a liquid ammonia nozzle (15) and a glow plug (16); the liquid ammonia nozzle (15) is connected to the outlet of the ammonia cylinder (21) through a liquid ammonia pipeline (17); a booster pump (18) and a second mass flow meter (19) are provided on the liquid ammonia pipeline (17); the liquid ammonia nozzle (15) and the glow plug (16) are both electrically connected to the control device (30); and the second mass flow meter (19) is electrically connected to the first display device (50).

9. The ammonia-diesel dual-fuel engine combustion control system according to any one of claims 1 to 5, characterized in that: During the operation of the engine (10), ammonia and diesel form an ammonia-diesel mixture inside the engine (10), and the overall excess air coefficient λ of the ammonia-diesel mixture can be calculated by the following formula (1); （1） in, is the theoretical air-fuel ratio of the ammonia-diesel mixture, It can be calculated by the following formula (2); （2） in, is the theoretical air-fuel ratio of pure diesel, is the theoretical air-fuel ratio of pure ammonia, is the mass flow rate of ammonia in the intake pipe, is the flow rate of diesel; is the actual air-fuel ratio of the ammonia-diesel mixture. If low-pressure ammonia injection is used It can be calculated by the following formula (3); （3） If high-pressure liquid ammonia injection is used, It can be calculated by the following formula (4); （4） in, is the air flow rate in the intake pipe.

10. A combustion control method for an ammonia-diesel dual-fuel engine, the control method being based on the combustion control system for an ammonia-diesel dual-fuel engine according to any one of claims 1 to 9, characterized in that: The engine adopts a control strategy with an overall excess air coefficient of 1.0 and a compression ratio of 18-23 to reduce nitrogen oxide and particulate matter emissions in the exhaust gas. The control method includes: When the ammonia replacement rate is less than 30%, the diesel electronically controlled nozzle (11) is controlled to perform a pre-injection at 10°-20°CA before the top dead center, and the diesel electronically controlled nozzle (11) is controlled to perform a main injection at 2°-4°CA before the top dead center; When the ammonia replacement rate is between 30% and 70%, the diesel electronically controlled nozzle (11) is controlled to perform pre-injection at 20° to 60° CA before the top dead center, the diesel electronically controlled nozzle (11) is controlled to perform main injection at 2° to 4° CA before the top dead center, and the diesel electronically controlled nozzle (11) is controlled to perform post-injection at 10° to 40° CA before the top dead center; When the ammonia replacement rate is between 70% and 100%, the diesel electronically controlled nozzle (11) is controlled to perform main injection at 0° to 10° CA before the top dead center, and the liquid ammonia nozzle (15) is controlled to perform liquid ammonia injection at 20° to 300° CA before the top dead center.

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