An ammonia fuel internal combustion engine combustion device

Abstract

The present invention discloses an ammonia fuel internal combustion engine combustion device, belonging to the technical field of internal combustion engine combustion. It includes a hydrogen-assisted ammonia fuel injector, an ammonia catalytic cracking device, an ammonia-hydrogen combustion system, an ammonia fuel pressure tank, and a hydrogen booster pump; the upper part of the hydrogen-assisted ammonia fuel injector is provided with an ammonia fuel injector, the middle part is provided with an ammonia-hydrogen mixing chamber, and the lower part is provided with a hydrogen injector; one side wall lower end of the ammonia fuel pressure tank is connected to the inlet of the ammonia catalytic cracking device through a pipeline for transporting ammonia to the ammonia catalytic cracking device to produce hydrogen through catalytic cracking. The present invention realizes combustion on an internal combustion engine with only one kind of ammonia fuel, the system is simple and convenient to use; direct injection at low pressure in the cylinder, with low cost, high reliability, and high thermal efficiency; compared with the existing hydrocarbon fuels, ammonia is a carbon-free fuel without the problem of CO2 greenhouse gas emissions, and part of the ammonia is catalytically cracked into hydrogen and then participates in combustion together, which is beneficial to realizing rapid combustion, solving the problem of slow ammonia combustion speed, and improving the thermal efficiency.

Description

Technical Field

[0001] The present invention relates to a combustion device for an ammonia-fuel internal combustion engine, belonging to the technical field of internal combustion engine combustion. Background Art

[0002] Internal combustion engines are the main power sources in the transportation field. Traditional internal combustion engines use fossil energy as fuel, generate heat through combustion, and then perform external work through thermal work conversion. Fossil energy belongs to hydrocarbon fuels, and the application of internal combustion engines inevitably produces emission pollutants such as NOx, PM, HC, CO, and CO2. And CO2 is a greenhouse gas and the main culprit of global warming. In order to control global warming, the Paris Agreement was adopted at the Paris Climate Change Conference on December 12, 2015. The long-term goal of the Paris Agreement is to control the increase in the global average temperature within 2 degrees Celsius above the pre-industrial level and strive to limit the temperature increase within 1.5 degrees Celsius, and also proposes to achieve a balance between anthropogenic greenhouse gas emissions and removals in the second half of this century.

[0003] All fields have turned to the research and development of low-carbon or carbon-free new energy application technologies. As for internal combustion engines, the research and development of hydrogen / ammonia carbon-free fuel combustion technologies have also emerged. In particular, hydrogen fuel burns very cleanly in internal combustion engines. Except for NOx emissions, there are no harmful emissions such as CO2, CO, HC, and PM generated by hydrocarbon fuel combustion. However, due to the low energy density, difficult storage and transportation, and poor safety of hydrogen fuel, it is not very realistic to commercially apply hydrogen fuel in internal combustion engines at present. And ammonia fuel, which is also carbon-free as a hydrogen energy carrier, is comparable to existing gasoline and diesel in terms of energy density, preparation, storage and transportation, and safety. Therefore, it may become a better carbon-free alternative fuel for internal combustion engines. However, due to the high auto-ignition temperature, slow combustion speed, and high ignition energy of ammonia, there are technical difficulties to overcome in its application in internal combustion engines.

[0004] The existing technology for realizing normal combustion of ammonia fuel in internal combustion engines is to use a combustion improver, such as diesel, gasoline, etc., to participate in combustion together with ammonia. For example, as Figure 1 shown, it can be seen from the figure that in order to realize the normal combustion of ammonia fuel in existing internal combustion engines, Figure 1The device shown requires a hydrocarbon fuel such as diesel as an ignition improver. That is, ammonia fuel is sprayed into the intake passage 303, mixed with air, and enters the engine combustion chamber 9 during the intake stroke to form an ammonia-air mixture (the specific structure is that the ammonia fuel pressure tank 4 is connected to the ammonia fuel pressure rail 7 through a conduit, and the other end of the ammonia fuel pressure rail 7 is connected to the top of the ammonia fuel injector 101 through a pipe. The intake passage 303 is installed on the engine cylinder head 301 and extends into the combustion chamber 9, and the bottom of the ammonia fuel injector 101 is connected to the intake passage 303). As an ignition improver for the hydrocarbon fuel, the hydrocarbon fuel is sucked from the hydrocarbon fuel tank 11 into the hydrocarbon fuel booster pump 12, pressurized, sent to the hydrocarbon fuel rail 13, and finally sent to the hydrocarbon fuel injector 10. After being started by a trigger signal, the hydrocarbon fuel is sprayed into the combustion chamber 9 near the compression top dead center (the specific structure is: one end of the hydrocarbon fuel tank 11 is connected to the hydrocarbon fuel booster pump 12 through a conduit, the outlet end of the hydrocarbon fuel booster pump 12 is connected to the hydrocarbon fuel rail 13 through a conduit, the other end of the hydrocarbon fuel rail 13 is connected to the top of the hydrocarbon fuel injector 10 through a conduit, the hydrocarbon fuel injector 10 is installed on the engine cylinder head 301 and extends into the combustion chamber 9, and an exhaust passage 304 is also provided on the engine cylinder head 301). After the hydrocarbon fuel such as diesel is first compressed and ignited, the temperature and pressure of the ammonia-air mixture in the engine cylinder increase sharply, causing the ammonia fuel to catch fire and realizing the normal combustion of the ammonia fuel. It can be seen that the prior art requires two fuel injection systems, namely an ammonia fuel injection system and a hydrocarbon fuel injection system, with a complex system and troublesome fuel filling; moreover, the main fuel ammonia is injected outside the engine cylinder, resulting in a lower thermal efficiency compared with in-cylinder direct injection; furthermore, the participation of the hydrocarbon fuel ignition improver inevitably generates the greenhouse gas CO2.

[0005] Therefore, in view of the above defects, it is necessary to design an internal combustion engine combustion device that uses only ammonia fuel to solve the above defects. Summary of the Invention

[0006] The present invention aims at the technical problems mentioned in the above background art and adopts the following technical solutions to achieve:

[0007] An ammonia fuel internal combustion engine combustion device includes a hydrogen-assisted ammonia fuel injector, an ammonia catalytic cracking device, an ammonia-hydrogen combustion system, an ammonia fuel pressure tank, and a hydrogen booster pump; an ammonia fuel injector is provided at the upper part of the hydrogen-assisted ammonia fuel injector, an ammonia-hydrogen mixing chamber is provided in the middle, and a hydrogen injector is provided at the lower part;

[0008] The ammonia-hydrogen combustion system includes an engine cylinder head and a spark plug;

[0009] One end of the side wall at the lower part of the ammonia fuel pressure tank is connected to the inlet of the ammonia catalytic cracking device through a pipeline, for transporting ammonia into the ammonia catalytic cracking device to produce hydrogen through catalytic cracking. The top side wall of the ammonia fuel pressure tank is connected to an ammonia fuel pressure rail through a pipeline. The outlet end of the ammonia fuel pressure rail is connected to an ammonia fuel injector through a pipeline. The ammonia fuel injector is connected to the top of the hydrogen injector of the hydrogen-assisted ammonia fuel injector.

[0010] One end of the ammonia catalytic cracking device is connected to a hydrogen booster pump through a pipeline. The outlet end of the hydrogen booster pump is connected to a hydrogen pressure rail through a pipeline. The hydrogen pressure rail is connected to the inner top side wall of the hydrogen injector through a pipeline. The bottom of the hydrogen injector extends into the combustion chamber and is connected to the inside of the combustion chamber.

[0011] An ammonia-hydrogen mixing chamber is provided in the middle of the hydrogen-assisted ammonia fuel injector. The outlet end of the hydrogen pressure rail is connected to the ammonia-hydrogen mixing chamber through a pipeline for mixing ammonia and hydrogen. The ammonia-hydrogen mixing chamber is connected to the inner top side wall of the hydrogen injector.

[0012] A spark plug is installed on the engine cylinder head and is connected to the combustion chamber. The spark plug is close to the hydrogen injector for forming spray-guided combustion to achieve stratified combustion.

[0013] As a preferred example, the ammonia-hydrogen combustion system further includes an exhaust passage. One side wall of the exhaust passage is connected to an exhaust gas pipeline. The top of the exhaust gas pipeline is connected to the bottom of the ammonia catalytic cracking device for providing heat energy to the ammonia catalytic cracking device to promote the catalytic cracking of ammonia into hydrogen. One end of the exhaust passage is connected to the external environment, and the other end extends into the engine cylinder head and is connected to the combustion chamber.

[0014] As a preferred example, the ammonia-hydrogen combustion system further includes an intake passage and a piston. One end of the intake passage is installed on the engine cylinder head and is connected to the combustion chamber. The intake passage and the exhaust passage are symmetrically arranged on the engine cylinder head, and the piston is located inside the combustion chamber.

[0015] As a preferred example, both the ammonia fuel injector and the hydrogen injector of the hydrogen-assisted ammonia fuel injector are installed on the engine cylinder head.

[0016] Beneficial effects:

[0017] 1) Only one kind of ammonia fuel is used to achieve combustion on an internal combustion engine, with a simple system and convenient use.

[0018] 2) Low-pressure direct injection in the cylinder, with low cost, high reliability, and high thermal efficiency.

[0019] The present invention adopts the in-cylinder low-pressure hydrogen-assisted ammonia fuel injection technology. Compared with the existing in-cylinder high-pressure direct injection technology for diesel engines, the injection pressure is two orders of magnitude lower (for example, the pressure required for in-cylinder high-pressure direct injection of existing diesel engines is greater than 2000 bar, while the injection pressure of the present invention is less than 20 bar), and the reliability is good; compared with the intake port injection technology, the metering is accurate and the thermal efficiency is high.

[0020] 3) Compared with existing hydrocarbon fuels, ammonia is a carbon-free fuel and there is no problem of CO2 greenhouse gas emissions.

[0021] 4) Part of the ammonia is catalytically cracked into hydrogen and then participates in combustion together, which is conducive to achieving rapid combustion, solving the problem of slow ammonia combustion speed, and improving the thermal efficiency. Description of the Drawings

[0022] Figure 1 is a schematic structural diagram of the prior art;

[0023] Figure 2 is a schematic diagram of the device of the present invention;

[0024] In the figure: 1 - hydrogen-assisted ammonia fuel injector; 101 - ammonia fuel injector; 102 - ammonia-hydrogen mixing chamber; 103 - hydrogen injector; 2 - ammonia catalytic cracking device; 3 - ammonia-hydrogen combustion system; 301 - engine cylinder head; 302 - piston; 303 - intake port; 304 - exhaust port; 305 - spark plug; 4 - ammonia fuel pressure tank; 5 - hydrogen booster pump; 6 - exhaust gas passage; 7 - ammonia fuel pressure rail; 8 - hydrogen pressure rail; 9 - combustion chamber; 10 - hydrocarbon fuel injector; 11 - hydrocarbon fuel tank; 12 - hydrocarbon fuel booster pump; 13 - hydrocarbon fuel rail. Detailed Embodiments

[0025] In order to make it easy to understand the technical means, creative features, achieved purposes and effects of the present invention, the present invention will be further described below with reference to specific drawings.

[0026] As Figure 2 shown, an ammonia fuel internal combustion engine combustion device includes a hydrogen-assisted ammonia fuel injector 1, an ammonia catalytic cracking device 2, an ammonia-hydrogen combustion system 3, an ammonia fuel pressure tank 4, and a hydrogen booster pump 5; the hydrogen-assisted ammonia fuel injector 1 includes an ammonia fuel injector 101 at the upper part, an ammonia-hydrogen mixing chamber 102 in the middle, and a hydrogen injector 103 at the lower part; the ammonia-hydrogen combustion system 3 includes an engine cylinder head 301 and a spark plug 305;

[0027] One end of the side wall at the lower part of the ammonia fuel pressure tank 4 is connected to the inlet of the ammonia catalytic cracking device 2 through a pipeline, for transporting ammonia into the ammonia catalytic cracking device 2, and hydrogen is produced through catalytic cracking. The top side wall of the ammonia fuel pressure tank 4 is connected to an ammonia fuel pressure rail 7 through a pipeline. The outlet end of the ammonia fuel pressure rail 7 is connected to an ammonia fuel injector 101 through a pipeline. The ammonia fuel injector 101 is connected to the top of a hydrogen injector 103 of the hydrogen-assisted ammonia fuel injector 1.

[0028] One end of the ammonia catalytic cracking device 2 is connected to a hydrogen booster pump 5 through a pipeline. The outlet end of the hydrogen booster pump 5 is connected to a hydrogen pressure rail 8 through a pipeline. The hydrogen pressure rail 8 is connected to the inner top side wall of the hydrogen injector 103 through a pipeline. The bottom of the hydrogen injector 103 extends into the combustion chamber 9 and is connected to the inside of the combustion chamber 9.

[0029] An ammonia-hydrogen mixing chamber 102 is provided in the middle of the hydrogen-assisted ammonia fuel injector 1. The outlet end of the hydrogen pressure rail 8 is connected to the ammonia-hydrogen mixing chamber 102 through a pipeline, for mixing ammonia and hydrogen; the ammonia-hydrogen mixing chamber 102 is connected to the inner top side wall of the hydrogen injector 103.

[0030] A spark plug 305 is installed on the engine cylinder head 301 and is connected to the combustion chamber 9, and the spark plug 305 is close to the hydrogen injector 103, for forming spray-guided combustion and realizing stratified combustion.

[0031] The ammonia-hydrogen combustion system 3 further includes an exhaust passage 304. One side wall of the exhaust passage 304 is connected to an exhaust gas pipeline 6. The top of the exhaust gas pipeline 6 is connected to the bottom of the ammonia catalytic cracking device 2, for providing heat energy to the ammonia catalytic cracking device 2 to promote the catalytic cracking of ammonia into hydrogen. One end of the exhaust passage 304 is connected to the external environment, and the other end extends into the engine cylinder head 301 and is connected to the combustion chamber 9.

[0032] The ammonia-hydrogen combustion system 3 further includes an intake passage 303 and a piston 302. One end of the intake passage 303 is installed on the engine cylinder head 301 and is connected to the combustion chamber 9. The intake passage 303 and the exhaust passage 304 are symmetrically arranged on the engine cylinder head 301, and the piston 305 is located inside the combustion chamber 9.

[0033] Both the ammonia fuel injector 101 and the hydrogen injector 103 of the hydrogen-assisted ammonia fuel injector 1 are installed on the engine cylinder head 301.

[0034] Working principle: When the internal combustion engine is running, at a certain moment during the upward movement of the piston 302 in the compression stroke, the ammonia fuel injector 101 of the hydrogen-assisted ammonia fuel injector 1 starts to open first, injecting the ammonia fuel in the ammonia fuel pressure rail 7 into the middle ammonia-hydrogen mixing chamber 102 at a pressure P1. This ammonia-hydrogen mixing chamber 102 is connected to the hydrogen pressure rail 8. Therefore, ammonia and hydrogen are mixed in the ammonia-hydrogen mixing chamber 102;

[0035] After a certain period of time, when the lower hydrogen injector 103 opens, the ammonia-hydrogen mixture in the ammonia-hydrogen mixing chamber 102 is sprayed into the combustion chamber 9 at a pressure P2. During this process, the compressed hydrogen expands to tear the droplets of the ammonia spray, improving the spray quality;

[0036] The hydrogen injection amount only needs to be about 30% of the total ammonia-hydrogen injection amount;

[0037] The ammonia catalytic cracking device 2 introduces a part of ammonia from the ammonia fuel pressure tank 4 for catalytic cracking to produce hydrogen. A part of the exhaust gas in the exhaust passage 304 of the engine is introduced into the ammonia catalytic cracking device 2 through the exhaust gas passage 6 to provide heat energy for promoting the catalytic cracking of ammonia into hydrogen. The hydrogen produced by cracking is then pressurized to P2 (P2 is less than P1) by the hydrogen booster pump 5 and then led to the hydrogen pressure rail 8 to be supplied to the hydrogen injector 103 of the hydrogen-assisted ammonia fuel injector 1;

[0038] The piston 302 continues to move upward, compressing the air in the cylinder and forming a certain air movement. When the hydrogen injector 103 opens near the top dead center of compression and sprays the ammonia-hydrogen mixture in the ammonia-hydrogen mixing chamber into the combustion chamber 9 at a pressure P2, guided by the spray and in cooperation with the air movement in the combustion chamber 9, an ammonia-hydrogen-air mixture with a stoichiometric ratio is formed near the spark plug 305, and the mixture gradually becomes leaner in the direction away from the spark plug 305 towards the periphery of the combustion chamber 9. In this way, a stratified ammonia-hydrogen-air mixture with a higher concentration near the spark plug 305 and gradually becoming leaner away from the spark plug 305 towards the periphery of the combustion chamber 9 is formed inside the entire combustion. Subsequently, at a certain moment near the top dead center of the compression stroke, the spark plug 305 is triggered to ignite, igniting the ammonia-hydrogen-air mixture, and the combustion starts from near the spark plug 305 and gradually advances towards the periphery of the combustion chamber 9. Since the diffusion of hydrogen in the combustion chamber 9 improves the ignition performance of the ammonia-hydrogen-air mixture, normal combustion is ensured.

[0039] Such a cycle ensures the normal operation of the internal combustion engine under a single ammonia fuel supply, achieving zero-carbon emission combustion.

[0040] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. An ammonia fuel internal combustion engine combustion device, characterized in that: It includes a hydrogen-assisted ammonia fuel injector, an ammonia catalytic cracking device, an ammonia-hydrogen combustion system, an ammonia fuel pressure tank, and a hydrogen booster pump; the upper part of the hydrogen-assisted ammonia fuel injector is provided with an ammonia fuel injector, the middle part is provided with an ammonia-hydrogen mixing chamber, and the lower part is provided with a hydrogen injector; The ammonia-hydrogen combustion system includes an engine cylinder head and a spark plug; One lower end side wall of the ammonia fuel pressure tank is connected and communicated with the inlet of the ammonia catalytic cracking device through a pipeline for transporting ammonia into the ammonia catalytic cracking device to produce hydrogen through catalytic cracking. The top side wall of the ammonia fuel pressure tank is connected and communicated with an ammonia fuel pressure rail through a pipeline. The outlet end of the ammonia fuel pressure rail is connected and communicated with the ammonia fuel injector through a pipeline, and the ammonia fuel injector is connected and communicated with the top of the hydrogen injector of the hydrogen-assisted ammonia fuel injector; One end of the ammonia catalytic cracking device is connected and communicated with a hydrogen booster pump through a pipeline. The outlet end of the hydrogen booster pump is connected and communicated with a hydrogen pressure rail through a pipeline. The hydrogen pressure rail is connected and communicated with the inner top side wall of the hydrogen injector through a pipeline. The bottom of the hydrogen injector extends into the combustion chamber and is connected and communicated with the inside of the combustion chamber; The outlet end of the hydrogen pressure rail is connected and communicated with the ammonia-hydrogen mixing chamber through a pipeline for mixing ammonia and hydrogen; the ammonia-hydrogen mixing chamber is connected and communicated with the inner top side wall of the hydrogen injector for spraying the ammonia fuel in the ammonia fuel pressure rail into the middle ammonia-hydrogen mixing chamber at a pressure P1, and the hydrogen produced by cracking then passes through the hydrogen booster pump and is pressurized to P2, and P2 is less than P1, and then leads to the hydrogen pressure rail to supply the hydrogen injector of the hydrogen-assisted ammonia fuel injector; the spark plug is installed on the engine cylinder head and is connected and communicated with the combustion chamber, and the spark plug is close to the hydrogen injector for forming spray-guided combustion to achieve stratified combustion; specifically: after a certain period of time, when the lower hydrogen injector is opened, the ammonia-hydrogen mixture in the ammonia-hydrogen mixing chamber is sprayed into the combustion chamber at a pressure P2. During this process, the compressed hydrogen expands and tears the droplets of the ammonia spray, improving the spray quality.

2. The combustion device of an ammonia-fuel internal combustion engine according to claim 1, wherein: The ammonia-hydrogen combustion system further includes an exhaust passage. One side wall of the exhaust passage is connected and communicated with an exhaust gas pipeline. The top of the exhaust gas pipeline is connected and communicated with the bottom of the ammonia catalytic cracking device for supplying heat energy to the ammonia catalytic cracking device to promote the catalytic cracking of ammonia into hydrogen. One end of the exhaust passage is connected and communicated with the external environment, and the other end extends into the engine cylinder head and is connected and communicated with the combustion chamber.

3. The combustion device of an ammonia-fuel internal combustion engine according to claim 2, characterized in that: The ammonia-hydrogen combustion system further includes an intake passage and a piston. One end of the intake passage is installed on the engine cylinder head and is connected and communicated with the combustion chamber. The intake passage and the exhaust passage are symmetrically arranged on the engine cylinder head, and the piston is located inside the combustion chamber.

4. A combustion device for an ammonia-fuel internal combustion engine according to claim 1, characterized in that: Both the ammonia fuel injector and the hydrogen injector of the hydrogen-assisted ammonia fuel injector are installed on the engine cylinder head.

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