Ammonia-diesel dual-fuel engine with opposed pistons
The opposed-piston ammonia-diesel dual-fuel engine design with an ammonia combustion chamber and strategic injector placement and heating rods enhances mixing and combustion efficiency, addressing poor mixing and ignition issues, and improving ammonia utilization.
Patent Information
- Application Number
- CN202411512578.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-28
- Publication Date
- 2024-12-10
AI Technical Summary
Opposed-piston ammonia-diesel engines face challenges with poor mixing of the combustion mixture, difficulty in ammonia combustion, low indicated efficiency, and low ammonia fuel utilization due to high ignition temperature and low flame propagation speed, leading to environmental pollution from unburned ammonia.
An opposed-piston ammonia-diesel dual-fuel engine design featuring an ammonia combustion chamber connected to the main combustion chamber through a channel, with an ammonia injector and diesel injector, electromagnetic heating rods, and a ceramic fiber coating to enhance mixing and combustion efficiency.
Improves combustion efficiency by forming concentrated and stratified ammonia mixtures, addressing poor mixing and ignition issues, and enhancing ammonia utilization, reducing emissions.
Smart Images
Figure CN119102873A_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the technical field of opposed piston engines, and in particular relates to an opposed piston ammonia-diesel dual-fuel engine. Background Art
[0002] Compared with the traditional four-stroke engine, the opposed-piston two-stroke engine has no cylinder head and valve structure. Instead, two opposed pistons are arranged in the same cylinder. The mixture of fuel and air burns in the enclosed space composed of the intake piston, exhaust piston and cylinder liner to complete the energy conversion. The lack of cylinder head and valve structure greatly improves the compactness and power-to-weight ratio of the opposed-piston two-stroke engine.
[0003] The greenhouse effect and other environmental problems caused by the widespread use of carbon dioxide emitted by engines are becoming increasingly prominent. Ammonia completely burns to produce water and nitrogen, and has broad application prospects as an alternative fuel for engines. However, due to the high working frequency of opposed-piston two-stroke engines and the harsh air port ventilation process, the mixing of the combustion mixture is poor. In addition, ammonia has a high ignition temperature, poor ignition performance, and low flame propagation speed, resulting in low engine indication efficiency. A large amount of unburned ammonia will also enter the external environment through the exhaust pipe, causing environmental pollution. Therefore, how to achieve efficient utilization of ammonia has become an urgent problem to be solved in opposed-piston ammonia-diesel engines. Summary of the invention
[0004] In view of this, the present application aims to propose an opposed-piston ammonia-diesel dual-fuel engine to solve the problems of poor mixing of the combustion mixture of the opposed-piston ammonia engine, difficulty in ammonia combustion, low indicated efficiency and low ammonia fuel utilization, so as to achieve efficient utilization of ammonia fuel in the opposed-piston engine.
[0005] To achieve the above purpose, the technical solution of this application is implemented as follows:
[0006] The present application provides an opposed piston ammonia-diesel dual fuel engine, comprising a cylinder liner, an intake piston, a diesel injector, an exhaust piston, an ammonia injector, and an ammonia combustion chamber;
[0007] The intake piston and the exhaust piston are arranged opposite to each other in the cylinder liner, and the enclosed area of the intake piston, the exhaust piston and the cylinder liner forms a main combustion chamber;
[0008] The ammonia combustion chamber is connected to the main combustion chamber through an ammonia combustion chamber channel, and the ammonia injector is arranged on the outer wall of the ammonia combustion chamber and corresponds to the ammonia combustion chamber channel;
[0009] The diesel injector is arranged on the outer wall of the cylinder liner and corresponds to the outlet of the ammonia combustion chamber channel.
[0010] Furthermore, a pit is provided on the end surface of the intake piston and the exhaust piston which are close to each other, and a main combustion chamber is formed between the two pits.
[0011] Further, the ammonia combustion chamber is a centrally symmetrical spherical or ellipsoidal structure, and is provided as an integral structure with the ammonia combustion chamber channel, and the ammonia injector is located on the center line of the ammonia combustion chamber and the ammonia combustion chamber channel;
[0012] The center line of the ammonia combustion chamber channel and the center line of the diesel injector form an angle.
[0013] Furthermore, the angle is selected to be 90° to 180° according to the engine swirl ratio.
[0014] Furthermore, at least two electromagnetic heating rods are arranged circumferentially on the outer wall of the ammonia combustion chamber.
[0015] Furthermore, the outer surface of the ammonia combustion chamber is coated with a coating layer.
[0016] Furthermore, the coating layer is ceramic fiber.
[0017] Compared with the prior art, the opposed piston ammonia-diesel dual-fuel engine described in this application has the following beneficial effects:
[0018] An opposed-piston ammonia-diesel dual-fuel engine described in the present application is provided with an ammonia combustion chamber on the outside of the cylinder liner, the ammonia combustion chamber is connected to the main combustion chamber through an ammonia combustion chamber channel, and under the action of an ammonia injector and a diesel injector, ammonia in the ammonia combustion chamber is driven by an intake vortex to form a relatively concentrated ammonia mixture with diesel and air, and ammonia, diesel and air in the main combustion chamber form a relatively thin ammonia mixture, thereby solving the problem of poor mixing of the combustion mixture of ammonia, diesel and fresh air caused by the high working frequency and harsh air port ventilation process of the opposed-piston two-stroke engine; at the same time, in the main combustion chamber and the ammonia combustion chamber, the mixtures with different ammonia concentrations form stratified multiple combustion of ammonia, thereby solving the problems of high ammonia ignition temperature, poor ignition performance, low flame propagation speed and low ammonia utilization rate, and improving the engine combustion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:
[0020] Figure 1 This is a schematic diagram of the structure of an opposed piston ammonia-diesel dual-fuel engine according to an embodiment of the present application;
[0021] Figure 2This is a plan cross-sectional view of an opposed piston ammonia-diesel dual-fuel engine according to an embodiment of the present application;
[0022] Figure 3 This is a schematic diagram of the working medium flow in the ammonia combustion chamber during the compression stroke of an opposed-piston ammonia-diesel dual-fuel engine described in an embodiment of the present application.
[0023] Description of reference numerals:
[0024] 1-cylinder liner; 2-intake piston; 3-diesel injector; 4-exhaust piston; 5-main combustion chamber; 6-electromagnetic heating rod; 7-ammonia injector; 8-ammonia combustion chamber; 81-coating layer; 82-ammonia combustion chamber channel. DETAILED DESCRIPTION
[0025] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.
[0026] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should be the usual meanings understood by people with ordinary skills in the field to which the present application belongs. The "first", "second" and similar words used in the embodiments of the present application do not represent any order, quantity or importance, but are only used to distinguish different components. "Including" or "comprising" and similar words mean that the elements or objects appearing in front of the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.
[0027] See also Figure 1 and Figure 2 As shown, this embodiment provides an opposed piston ammonia-diesel dual fuel engine, including a cylinder liner 1, an intake piston 2, a diesel injector 3, an exhaust piston 4, an ammonia injector 7, and an ammonia combustion chamber 8;
[0028] The intake piston 2 and the exhaust piston 4 are arranged opposite to each other in the cylinder liner 1, and the enclosed area of the intake piston 2, the exhaust piston 4 and the cylinder liner 1 forms a main combustion chamber 5;
[0029] The ammonia combustion chamber 8 is connected to the main combustion chamber 5 through the ammonia combustion chamber passage 82, and the ammonia injector 7 is arranged on the outer wall of the ammonia combustion chamber 8 and corresponds to the ammonia combustion chamber passage 82;
[0030] The diesel injector 3 is disposed on the outer wall of the cylinder liner 1 and corresponds to the outlet of the ammonia combustion chamber passage 82 .
[0031] Specifically, in the present embodiment, the engine used is an opposed piston two-stroke engine, which is different from the existing two-stroke or four-stroke engine. The engine does not have a cylinder head and a valve structure. However, due to the high working frequency and harsh air port ventilation process of the opposed piston two-stroke engine, the mixing property of the combustion mixture of ammonia, diesel and fresh air is poor. Therefore, in the present embodiment, an ammonia combustion chamber 8 is arranged outside the cylinder liner 1, and the ammonia combustion chamber channel 82 of the ammonia combustion chamber 8 is connected to the main combustion chamber 5. Under the action of the ammonia injector 7 and the diesel injector 3, the ammonia in the ammonia combustion chamber 8 forms a relatively concentrated ammonia mixture with the diesel and the air under the drive of the intake vortex, and the ammonia, diesel and the air in the main combustion chamber 5 form a relatively thin ammonia mixture, thereby solving the problem of poor mixing property of the combustion mixture of ammonia, diesel and fresh air caused by the high working frequency and harsh air port ventilation process of the opposed piston two-stroke engine.
[0032] At the same time, in the main combustion chamber 5 and the ammonia combustion chamber 8, the mixed gases with different ammonia concentrations form stratified multiple combustion of ammonia, which solves the problems of high ammonia ignition temperature, poor ignition performance, low flame propagation speed and low ammonia utilization rate, and improves the engine combustion efficiency.
[0033] In some embodiments, a recess is provided on the end surface of the intake piston 2 and the exhaust piston 4 that are close to each other, and a main combustion chamber 5 is formed between the two recesses.
[0034] Specifically, in this embodiment, since the opposed-piston two-stroke engine has no cylinder head, the diesel injector 3 is arranged on the outer wall of the cylinder liner 1 and is located between the intake piston 2 and the exhaust piston 4. Then, a main combustion chamber 5 is formed in the area between the intake piston 2, the exhaust piston 4 and the inner wall of the cylinder head, and a diesel-air mixture containing a small amount of ammonia burns in the main combustion chamber 5.
[0035] In some embodiments, the ammonia combustion chamber 8 is a centrally symmetrical spherical or ellipsoidal structure, and is arranged as an integral structure with the ammonia combustion chamber channel 82. The center line of the ammonia combustion chamber channel 82 forms an angle with the center line of the diesel injector 3, and the angle is selected to be 90° to 180° according to the engine swirl ratio.
[0036] Specifically, in the present embodiment, an ammonia combustion chamber 8 with a spherical or ellipsoidal structure is provided, the ammonia combustion chamber 8 is provided outside the cylinder liner 1, and the ammonia combustion chamber channel 82 of the ammonia combustion chamber 8 is connected with the main combustion chamber 5. During the gas combustion process, due to the pressure difference between the main combustion chamber 5 and the ammonia combustion chamber 8, the mixed gas will flow between the ammonia combustion chamber 8 and the main combustion chamber 5, thereby realizing stratified and multiple combustions of different ammonia concentrations, thereby improving the engine combustion efficiency.
[0037] It should be noted that the swirl ratio is a parameter that measures the intensity of air rotation in the combustion chamber. It has a great influence on the performance of the engine. A higher swirl ratio can usually enhance the mixing of fuel and air, thereby improving the uniformity of combustion, reducing the emission of unburned matter, and improving thermal efficiency; but an excessively high swirl ratio may lead to excessively strong mixing, which is not conducive to the expansion of the fire core, slowing down the combustion speed and reducing power output.
[0038] In the present application, an angle is formed between the center line of the ammonia combustion chamber channel 82 and the center line of the diesel injector 3, that is, the outlet angle of the ammonia combustion chamber channel is limited. Since the ventilation frequency of the opposed two-stroke engine is high, the existence of the angle can guide the airflow to produce specific vortex and turbulent structures, enhance the air flow in the combustion chamber, and the fuel (ammonia) of the ammonia combustion chamber 8 and the fuel (diesel) of the diesel injector 3 enter the combustion chamber at different angles, which can promote the full mixing of the two fuels and air to form a more uniform mixed gas, which helps to improve combustion efficiency.
[0039] In this embodiment, the angle is set to 90° to 180°. A large number of tests have proved that when the airflow enters the ammonia combustion chamber 8, it will produce a stronger rotational motion and a higher swirl ratio, which can improve the mixing degree of fuel and air and is suitable for working conditions that require efficient combustion and reduced emissions; at the same time, the angle can ensure that the airflow formed by ammonia, diesel and air can be evenly distributed in the ammonia combustion chamber 8, and the combustion is more uniform. Setting it to an acute angle not only affects the swirl ratio, resulting in insufficient mixing of ammonia, diesel and air, which is not conducive to organizing combustion; it also affects the distribution of the airflow in the combustion chamber, causing the airflow to be concentrated in a certain area of the combustion chamber, resulting in uneven combustion, increasing local high-temperature areas, and possibly causing an increase in nitrogen oxide (NOx) emissions.
[0040] In some embodiments, at least two electromagnetic heating rods 6 are arranged circumferentially on the outer wall of the ammonia combustion chamber 8 to increase the heating temperature in the ammonia combustion chamber 8 .
[0041] In some embodiments, the outer surface of the ammonia combustion chamber 8 is coated with a coating layer 81 , and the coating layer 81 is ceramic fiber.
[0042] Specifically, in the present embodiment, ceramic fibers are coated on the outer surface of the ammonia combustion chamber 8. The test data analysis proves that the ammonia combustion chamber 8 using ceramic fibers has better thermal insulation performance, can effectively reduce heat, and improve combustion efficiency. Compared with the traditional brittle silicon nitride ceramics, alumina ceramics or zirconium oxide ceramics (which are prone to cracks or breakage under thermal shock or mechanical stress), ceramic fibers have certain flexibility, can better adapt to thermal expansion and contraction, and reduce the risk of coating cracking. Moreover, the density of ceramic fibers is relatively low, which can significantly reduce the overall weight of the combustion chamber and reduce the structural load of the equipment.
[0043] The working principle of the opposed piston ammonia-diesel dual fuel engine described in this embodiment is as follows:
[0044] (1) During the engine compression process, the air in the cylinder enters the ammonia combustion chamber 8 through the ammonia combustion chamber passage 82 to form a Figure 3 As shown in the intake vortex, at a certain moment of the compression stroke, the ammonia injector 7 injects ammonia into the ammonia combustion chamber 8, and the ammonia spray is fully mixed with the fresh air under the action of the strong vortex. Due to the presence of the coating layer 81 and the electromagnetic heating rod 6, an ammonia mixture with a higher temperature and a larger ammonia concentration is formed in the ammonia combustion chamber 8. The presence of the ammonia combustion chamber 8 solves the problem of poor mixing of the combustion mixture of ammonia, diesel and fresh air due to the high working frequency and harsh air port ventilation process of the opposed piston two-stroke engine.
[0045] (2) Near the compression top dead center, the diesel injector 3 injects diesel into the main combustion chamber 5. The diesel-air mixture containing a small amount of ammonia burns at high temperature and high pressure. At this time, the pressure of the main combustion chamber 5 is higher than that of the ammonia combustion chamber 8. The combustion fire core enters the ammonia combustion chamber 8 under the action of the pressure difference, igniting the ammonia, diesel, and air mixture with a higher temperature and ammonia concentration, forming a concentrated ammonia combustion. As the piston gradually moves away from the top dead center, the pressure of the ammonia combustion chamber 8 is greater than that of the main combustion chamber 5, and the incompletely burned concentrated ammonia mixture jets into the main combustion chamber 5, forming a lean ammonia secondary combustion. Multiple combustions with different ammonia concentrations solve the problems of high ammonia ignition temperature, poor ignition performance, low flame propagation speed, and low ammonia utilization, and improve the engine combustion efficiency.
[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.
[0047] The embodiments of the present application are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present application should be included in the scope of protection of the present application.
Claims
1. An opposed piston ammonia-diesel dual fuel engine, characterized in that: It comprises a cylinder liner (1), an intake piston (2), a diesel injector (3), an exhaust piston (4), an ammonia injector (7), and an ammonia combustion chamber (8); The intake piston (2) and the exhaust piston (4) are arranged opposite to each other in the cylinder liner (1), and the enclosed area of the intake piston (2), the exhaust piston (4) and the cylinder liner (1) forms a main combustion chamber (5); The ammonia combustion chamber (8) is connected to the main combustion chamber (5) through an ammonia combustion chamber passage (82); the ammonia injector (7) is arranged on the outer wall of the ammonia combustion chamber (8) and corresponds to the ammonia combustion chamber passage (82); The diesel injector (3) is arranged on the outer wall of the cylinder liner (1) and corresponds to the outlet of the ammonia combustion chamber channel (82).
2. The opposed piston ammonia-diesel dual fuel engine according to claim 1, characterized in that: A concave pit is provided on the end surface of the intake piston (2) and the exhaust piston (4) on one side close to each other, and a main combustion chamber (5) is formed between the two concave pits.
3. The opposed piston ammonia-diesel dual fuel engine according to claim 1, characterized in that: The ammonia combustion chamber (8) is a centrally symmetrical spherical or ellipsoidal structure, and is arranged as an integral structure with the ammonia combustion chamber channel (82); the ammonia injector (7) is located on the center line of the ammonia combustion chamber (8) and the ammonia combustion chamber channel (82); The center line of the ammonia combustion chamber channel (82) and the center line of the diesel injector (3) form an angle.
4. The opposed piston ammonia-diesel dual fuel engine according to claim 1, characterized in that: The angle is selected to be 90° to 180° according to the engine swirl ratio.
5. The opposed piston ammonia-diesel dual fuel engine according to claim 1, characterized in that: At least two electromagnetic heating rods (6) are arranged circumferentially on the outer wall of the ammonia combustion chamber (8).
6. The opposed piston ammonia-diesel dual fuel engine according to claim 1, characterized in that: The outer surface of the ammonia combustion chamber (8) is coated with a coating layer (81).
7. The opposed piston ammonia-diesel dual fuel engine according to claim 6, characterized in that: The coating layer (81) is ceramic fiber.