A diesel-ammonia dual-fuel engine combustion system and combustion method using hydrogenation active reforming

Abstract

The purpose of the present invention is to provide a diesel-ammonia dual-fuel engine combustion system and combustion method using hydrogenation active reforming, including a single common rail dual injector, an ammonia fuel injector, a hydrogen injector, etc. In order to achieve the precision control of engine fuel injection, the ammonia fuel is supplied by multi-point injection in the intake duct, and the diesel fuel is supplied by high-low flow injection using a single common rail dual injector. According to the operating conditions of the diesel / ammonia dual-fuel engine, the present invention adopts two working modes, namely, a pure diesel combustion mode and a dual-fuel combustion mode, and at the same time adopts the Miller cycle to optimize the piston workmanship and dual reforming to improve the combustion activity of ammonia fuel, thereby reducing pollutant emissions under the full operating conditions of the engine.

Description

Technical Field

[0001] The present invention relates to an engine combustion system, in particular to a dual-fuel engine combustion system and method. Background Art

[0002] Ammonia is a nitrogen-hydrogen compound that produces no carbon emissions during combustion. It is currently the chemical product with the largest output besides sulfuric acid. It has a wide source and low cost. However, ammonia fuel has problems such as high flash point, high minimum ignition energy, slow combustion speed and low combustion temperature, which limits the widespread application of ammonia fuel engines.

[0003] Patent CN115111089A mentions a pre-combustion chamber ammonia fuel engine system, which uses direct injection of ammonia in the cylinder and ignites hydrogen through the pre-combustion chamber to complete combustion. The patent uses hydrogen as the catalytic decomposition of ammonia fuel, and uses hydrogen fuel cells and other equipment to provide energy for ammonia catalysis. The system only needs to provide ammonia fuel to reduce pollutant emissions, but the patent has high requirements for hydrogen purity, and there are technical blind spots in maintaining system stability and operating start conditions under full operating conditions of the engine. Summary of the invention

[0004] The purpose of the present invention is to provide a diesel ammonia dual-fuel engine combustion system and a combustion method using hydrogenation active reforming, which can take into account emission, power and economy under different working conditions and achieve efficient and clean combustion.

[0005] The object of the present invention is achieved in that:

[0006] The present invention discloses a diesel-ammonia dual-fuel engine combustion system using hydrogenation active reforming, which is characterized by comprising a cylinder head, a cylinder wall, a piston, a diesel fuel tank, an ammonia fuel storage tank, and a hydrogen gas storage tank. The cylinder head, the cylinder wall, and the piston form a cylinder. The cylinder head is provided with an injector a, an injector b, an intake valve, and an exhaust valve. The cylinder is connected to an intake manifold via an intake valve, and the cylinder is connected to an exhaust manifold via an exhaust valve. An ammonia fuel injector and a hydrogen injector are provided in the intake manifold. The diesel fuel tank is connected to an oil delivery pump, a fuel filter, an injection pump, and a high-pressure fuel rail in sequence. The high-pressure fuel rail is respectively connected to injector a and injector b. The ammonia fuel storage tank is connected to an ammonia fuel pump in sequence. The fuel delivery pump, ammonia fuel filter, ammonia injection pump, ammonia fuel rail, the ammonia fuel rail is connected to the ammonia fuel injector, the hydrogen gas storage tank is connected to the vaporizer and pressure regulator and the hydrogen gas rail in sequence, the hydrogen gas rail is connected to the hydrogen injector, the injector a is vertically installed on the cylinder head, and its axis coincides with the center line of the cylinder, the injector b is vertically installed on the cylinder head, and its axis is parallel to the axis of the injector a, the ammonia fuel injector is obliquely installed on the intake manifold, and the ammonia fuel injection direction points to the inside of the cylinder along the intake manifold, the hydrogen injector is obliquely installed on the intake manifold and the axis of the hydrogen injector is coplanar with the axis of the ammonia fuel injector, and the hydrogen injection direction intersects with the ammonia fuel injection direction.

[0007] The diesel-ammonia dual-fuel engine combustion system using hydrogenation active reforming of the present invention may also include:

[0008] 1. Both injector a and injector b have nozzles with multi-hole structures. The spray holes of injector a are evenly distributed, while the spray holes of injector b are of different sizes.

[0009] 2. The ammonia fuel injector has a mid-section heating and an axial needle type single-hole injector structure, and a heating resistor is installed in the middle of the ammonia fuel injector.

[0010] The invention discloses a diesel-ammonia dual-fuel engine combustion method using hydrogenation active reforming, which is characterized by comprising a pure diesel combustion mode: according to different engine operating conditions, the working states of injectors a and b are dynamically adjusted; when the engine is in starting, idling and low-load conditions, only injector b is in the working state, injector b starts to spray before compression top dead center, and the injection start point is delayed as the load increases; by using a small flow injector and making injector b work in a linear characteristic region, accurate control of the injection amount is achieved; when the engine is in a medium-high load condition, the injector a and injector b are simultaneously operated, and injector a works in a linear characteristic region, injector a starts to spray before compression top dead center, and the injection start point is delayed as the load increases; injector b performs diesel injection when the engine output power is greater than 75% of the rated power, thereby meeting the power requirement of the diesel / ammonia dual-fuel engine.

[0011] The diesel-ammonia dual-fuel engine combustion method using hydrogenation active reforming of the present invention may also include:

[0012] 1. Dual fuel combustion mode: Ammonia fuel injector, hydrogen injector and fuel injector b work together, the injection start point of ammonia fuel injector is 10℃A-40℃A after exhaust valve closing, and the injection end point is 10℃A-20℃A before intake valve closing. As the engine load increases, the injection start point is advanced accordingly, and the total calorific value of the injected ammonia fuel accounts for 80%-85% of the total fuel calorific value; the injection start point of hydrogen injector is 20℃A-50℃A after exhaust valve closing, and the injection end point is 10℃A-20℃A before ammonia fuel injector closing, and The injection start point is advanced as the injection amount of ammonia fuel increases, and the total calorific value of the injected hydrogen fuel accounts for 5%-10% of the total fuel calorific value; injector b injects before the compression top dead center and in the second half of the compression stroke, and the calorific value of the injected diesel fuel accounts for 10%-15% of the total fuel calorific value; when the ammonia fuel injector injects, hydrogen is injected at the same time, and injector b injects diesel during the cylinder compression process, and the low-temperature reaction active groups formed by the diesel pre-injection are used to further improve the reaction activity of the mixed gas in the cylinder, thereby realizing the double reforming of the activity of the mixed gas.

[0013] The advantages of the present invention are as follows: the present invention adopts a multi-mode fuel mixing supply method according to the different operating conditions of the diesel / ammonia dual-fuel engine, combines the Miller cycle to optimize the piston workmanship and double reforming to improve the combustion activity of the ammonia fuel, gives full play to the low-carbon fuel and multi-fuel complementary and synergistic advantages of the diesel / ammonia dual-fuel engine, improves the engine fuel injection precision control, and reduces the emission of engine pollutants, so that the diesel / ammonia dual-fuel engine can take into account the emission, power and economy under different operating conditions, realizes efficient and clean combustion of the ammonia-diesel dual-fuel engine, and gives full play to the advantages of ammonia fuel such as low pollution, high octane number and high economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural schematic diagram of the present invention;

[0015] Figure 2 is a schematic diagram of the structure of an ammonia fuel injector;

[0016] Figure 3 This is the fuel distribution diagram in the cylinder under low load condition in pure diesel combustion mode;

[0017] Figure 4 This is the fuel distribution diagram in the cylinder under medium and high load conditions in pure diesel combustion mode;

[0018] Figure 5 It is the fuel distribution diagram in the cylinder during the engine intake process in the dual-fuel combustion mode;

[0019] Figure 6 It is the fuel distribution diagram in the cylinder at medium and high load of the engine under the dual-fuel combustion mode;

[0020] Figure 7 It is a schematic diagram of the working phase range of the fuel injector under the pure diesel combustion mode;

[0021] Figure 8 It is a schematic diagram of the working phase range of the fuel injector in the dual fuel combustion mode;

[0022] Fig. 9 It is the working state of the fuel injector in the pure diesel combustion mode;

[0023] Fig.10 It is the working state of the fuel injector in the dual fuel combustion mode. DETAILED DESCRIPTION

[0024] The present invention is described in more detail below with reference to the accompanying drawings:

[0025] Combination Figure 1-10The present invention includes an injector a9, an injector b10, an ammonia fuel injector 7, a hydrogen injector 20, a high-pressure fuel rail 5, a cylinder head 11, an intake manifold 28, an intake valve 8, an exhaust valve 27, etc.; the injector a9 is vertically installed on the cylinder head 11, and its axis coincides with the center line of the cylinder; the injector b10 is vertically installed on the cylinder head 11, and its axis is parallel to the axis of the injector a9 and keeps a certain distance; the ammonia fuel injector 7 is obliquely installed on the intake manifold 28, and the ammonia fuel injection direction points to the inside of the cylinder along the intake manifold 28; the hydrogen injector 20 is obliquely installed on the intake manifold 28 and the axis of the hydrogen injector 20 is coplanar with the axis of the ammonia fuel injector 7, and the hydrogen injection direction intersects with the ammonia fuel injection direction, so as to form a counter-jet when the fuel is injected to enhance the mixing with the air. According to the operating conditions of the diesel / ammonia dual-fuel engine, two working modes, pure diesel combustion mode and dual-fuel combustion mode, are adopted. At the same time, Miller cycle and double reforming are used to improve the combustion activity of ammonia fuel, give full play to the low-carbon and multi-fuel complementary and synergistic advantages of diesel / ammonia dual-fuel engine fuel, optimize and control the fuel injection amount, injection timing and injection law of ammonia fuel injector 7, hydrogen injector 20, injector a9, and injector b10, so as to enhance the engine fuel injection accuracy and realize the control of fuel distribution in the cylinder, and improve the economy and power of the engine under all operating conditions.

[0026] The single common rail dual injector is composed of a high-pressure oil rail 5, an injector a9, an injector b10, etc.; the injectors a9 and b10 are connected to the high-pressure oil rail 5; the injectors a9 and b10 have multi-spray hole structure nozzles, the spray holes of the injector a9 are evenly distributed, and the spray holes of the injector b10 are of different sizes; the diesel injection amount of the injector a9 can meet the fuel supply requirements of the engine under medium and high loads and high speeds; the diesel injection amount of the injector b10 can meet the precise control of fuel supply under low-load and low-speed conditions, starting conditions, idling conditions, and active reforming and ignition conditions of ammonia fuel. The single common rail dual injector system can take into account the precise control requirements of large and small flows of the engine under different operating conditions.

[0027] The Miller cycle is used to improve the economy of the dual-fuel engine. A long expansion stroke and short compression stroke design is adopted. That is, during the intake process, the opening period of the intake valve 8 is shortened, and the intake valve 8 is closed before the piston reaches the bottom dead center, so that the cylinder compression ratio is smaller than the expansion ratio, thereby improving the thermal efficiency of the engine.

[0028] The ammonia fuel injector 7 has a mid-section heating and an axial needle type single-hole injector structure. A heating resistor 26 is installed in the middle of the ammonia fuel injector 7. The heating resistor 26 works in the ammonia fuel injection stage to promote the vaporization of the ammonia fuel and strengthen the disturbance between the ammonia fuel and the air in the intake stage to make the mixture uniform.

[0029] Double reforming is: when the diesel / ammonia dual-fuel engine works in dual-fuel mode, hydrogen is injected at the same time as the ammonia fuel injector 7 is injected. The flammable property of hydrogen can improve the reactivity of the ammonia fuel and air mixture. At the same time, the cross-injection of hydrogen and ammonia fuel can enhance the uniformity of the mixture with the air. Injector b10 performs multiple diesel injections during the cylinder compression process, and uses the low-temperature reactive groups formed by diesel pre-injection to further improve the reactivity of the mixture in the cylinder, thereby realizing double reforming of the mixture activity and solving the problem of slow combustion of ammonia fuel.

[0030] By comprehensively adjusting the injection amount, injection timing and injection pattern of injector a9, injector b10, ammonia fuel injector 7 and hydrogen injector 20, the fuel proportion distribution, concentration and combustion mode in the combustion process are changed. The patented diesel / ammonia dual-fuel engine can realize two working modes: pure diesel combustion mode and dual-fuel combustion mode. The specific implementation plan is as follows:

[0031] (1) In pure diesel combustion mode: According to different engine operating conditions, the working status of injector a9 and injector b10 is dynamically adjusted. When the engine is in starting, idling and low load conditions, only injector b10 is in working state. Injector b10 starts to spray before compression top dead center, and the injection start point is gradually delayed as the load increases to optimize the combustion timing. By using a small flow injector and making injector b10 work in the linear characteristic area, accurate control of the injection amount is achieved to improve the engine economy. When the engine is in medium and high load conditions, in order to solve the problem that the injection amount of injector b10 cannot meet the engine fuel flow demand, injector a9 and injector b10 are used to work at the same time, and it is ensured that injector a9 works in the linear characteristic area. Injector a9 starts to spray before compression top dead center, and the injection start point is gradually delayed as the load increases to optimize the combustion timing. At the same time, in order to prevent injector b10 from generating carbon deposition or ablation due to high temperature combustion, injector b10 performs diesel injection when the engine output power is greater than 75% of the rated power to meet the power requirements of the diesel / ammonia dual-fuel engine.

[0032] (2) In the dual-fuel combustion mode: the ammonia fuel injector 7, the hydrogen injector 20 and the fuel injector b10 work in coordination, the injection start point of the ammonia fuel injector 7 is 10°C A-40°C A after the exhaust valve 27 is closed, and the injection end point is 10°C A-20°C A before the intake valve 8 is closed. As the engine load increases, the injection start point is gradually advanced, and the total calorific value of the injected ammonia fuel accounts for 80%-85% of the total fuel calorific value; the injection start point of the hydrogen injector 20 is 20°C A-50°C A after the exhaust valve 27 is closed, and the injection end point is 10°C A-20°C A before the ammonia fuel injector is closed, and the injection start point is gradually advanced as the ammonia fuel injection amount increases, and the total calorific value of the injected hydrogen fuel accounts for 5%-10% of the total fuel calorific value; the fuel injector b10 performs multiple injections before the compression top dead center and in the second half of the compression stroke, and the calorific value of the injected diesel fuel accounts for 10%-15% of the total fuel calorific value. When the ammonia fuel injector 7 is injecting, hydrogen is injected at the same time. The flammable property of hydrogen can improve the reactivity of the ammonia fuel and air mixture. At the same time, the cross injection of hydrogen and ammonia fuel can enhance the uniformity of the mixture with air. Injector b10 performs multiple diesel injections during the cylinder compression process, and uses the low-temperature reactive groups formed by diesel pre-injection to further improve the reactivity of the mixture in the cylinder, thereby achieving dual reforming of the mixture activity, accelerating the flame propagation speed, completing combustion in a short time, reducing emissions, and providing strong power for the engine.

Claims

1. A combustion method of a diesel-ammonia dual-fuel engine combustion system using hydrogenation active reforming, characterized in that: The system comprises a cylinder head, a cylinder wall, a piston, a diesel fuel tank, an ammonia fuel storage tank, and a hydrogen gas storage tank. The cylinder head, the cylinder wall, and the piston form a cylinder. The cylinder head is provided with an injector a, an injector b, an intake valve, and an exhaust valve. The cylinder is connected to an intake manifold via an intake valve, and the cylinder is connected to an exhaust manifold via an exhaust valve. An ammonia fuel injector and a hydrogen injector are provided in the intake manifold. The diesel fuel tank is connected to a fuel delivery pump, a fuel filter, a fuel injection pump, and a high-pressure fuel rail in sequence. The high-pressure fuel rail is respectively connected to injector a and injector b. The ammonia fuel storage tank is connected to an ammonia fuel delivery pump, an ammonia fuel filter, an ammonia injector, and a high-pressure fuel rail in sequence. A pump, an ammonia fuel rail, the ammonia fuel rail is connected to an ammonia fuel injector, a hydrogen gas storage tank is connected to an evaporator and a pressure regulator, and a hydrogen gas rail in sequence, the hydrogen gas rail is connected to a hydrogen injector, an injector a is vertically mounted on a cylinder head, and its axis coincides with a center line of a cylinder, an injector b is vertically mounted on a cylinder head, and its axis is parallel to the axis of an injector a, an ammonia fuel injector is obliquely mounted on an intake manifold, and an ammonia fuel injection direction is directed toward the inside of the cylinder along the intake manifold, a hydrogen injector is obliquely mounted on an intake manifold, and the axis of the hydrogen injector is coplanar with the axis of the ammonia fuel injector, and the hydrogen injection direction intersects with the ammonia fuel injection direction; The method includes a pure diesel combustion mode: according to different engine operating conditions, the working states of injectors a and b are dynamically adjusted; when the engine is in starting, idling, and low-load conditions, only injector b is in a working state, injector b starts to spray before compression top dead center, and the injection start point is delayed as the load increases; by using a small flow injector and making injector b work in a linear characteristic region, accurate control of the injection amount is achieved; when the engine is in a medium-to-high load condition, injector a and injector b are used to work simultaneously, and injector a works in a linear characteristic region, injector a starts to spray before compression top dead center, and the injection start point is delayed as the load increases, and injector b performs diesel injection when the engine output power is greater than 75% of the rated power, so as to meet the power requirements of the diesel / ammonia dual-fuel engine; Dual fuel combustion mode: Ammonia fuel injector, hydrogen injector and fuel injector b work together. The injection start point of ammonia fuel injector is 10℃A-40℃A after exhaust valve closing, and the injection end point is 10℃A-20℃A before intake valve closing. As engine load increases, the injection start point is advanced accordingly. The total calorific value of the injected ammonia fuel accounts for 80%-85% of the total fuel calorific value; the injection start point of hydrogen injector is 20℃A-50℃A after exhaust valve closing, and the injection end point is 10℃A-20℃A before intake valve closing, and the injection The injection start point is advanced as the ammonia fuel injection amount increases, and the total calorific value of the injected hydrogen fuel accounts for 5%-10% of the total fuel calorific value; injector b injects before the compression top dead center and in the second half of the compression stroke, and the calorific value of the injected diesel fuel accounts for 10%-15% of the total fuel calorific value; when the ammonia fuel injector is injected, hydrogen is injected at the same time, and injector b injects diesel during the cylinder compression process, and the low-temperature reaction active groups formed by the diesel pre-injection are used to further improve the reaction activity of the mixture in the cylinder, thereby realizing double reforming of the activity of the mixture.

2. The combustion method of a diesel-ammonia dual-fuel engine combustion system using hydrogenation active reforming according to claim 1, characterized in that: Both the injector a and the injector b have nozzles with a multi-hole structure. The spray holes of the injector a are evenly distributed, while the spray holes of the injector b are of different sizes.

3. The combustion method of a diesel-ammonia dual-fuel engine combustion system using hydrogenation active reforming according to claim 1, characterized in that: The ammonia fuel injector is provided with a mid-section heating and an axial needle type single-hole injector structure, and a heating resistor is installed in the middle of the ammonia fuel injector.

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