Marine methanol engine combustion control method and system

Abstract

The invention relates to a combustion control method and system for a marine methanol engine. The method comprises the steps that released heat of corresponding heaters in all air cylinders and the methanol injection amount injected by corresponding methanol injectors are obtained, and the initial temperature of methanol before the methanol enters the methanol injectors is obtained; the total air inlet amount and the air inlet temperature of air of the marine methanol engine are obtained; based on the methanol injection amount, the total gas inlet amount, the gas inlet temperature and the initial temperature, the heating heat needed for heating the methanol mixed gas in each cylinder to the spontaneous ignition point is determined; the heating power of each heater is controlled through the transformer; in response to the fact that the released heat is larger than or equal to the heating heat, the heating power of the current heater is kept unchanged; and in response to the released heat being less than the heating heat, increasing the heating power of the heater until the released heat is greater than or equal to the heating heat. The problem that the marine methanol engine is difficult to start and burn is solved.

Description

Technical Field

[0001] This invention relates to the field of marine engine technology, and in particular to a combustion control method and system for a marine methanol engine. Background Technology

[0002] Diesel engines, as a type of internal combustion engine, are widely used in the marine industry due to their reliability, high thermal efficiency, good economy, and large output torque. The vast majority of ship power comes from diesel engines. Currently, diesel engines still primarily rely on petroleum fuels, which presents challenges such as emission control and petroleum supply security. Using cleaner fuels, such as methanol and natural gas, is one possible solution.

[0003] Methanol, with the molecular formula CH3OH, can be produced biologically from plant stalks such as corn and sugarcane, or renewablely through carbon capture and utilization. However, large-scale methanol production primarily relies on chemical and physical methods derived from minerals like coal and natural gas. Coal-to-methanol production not only alleviates the dependence of automotive internal combustion engines on petroleum energy but also facilitates the efficient utilization of high-sulfur coal resources, making it a significant alternative fuel for engines. Therefore, methanol is considered one of the most promising alternative fuels for engines to achieve widespread application.

[0004] Currently, using methanol as an alternative fuel for engines still presents some problems, such as the corrosiveness and toxicity of methanol, environmental pollution from residual methanol and formaldehyde after incomplete combustion, and the difficulty of cold starting pure methanol fuel. The specific reasons are as follows: (1) Methanol is corrosive. When used as a substitute fuel, it will cause certain corrosion to the relevant parts of the methanol supply system and injection system. Unburned methanol in the cylinder will flow into the crankcase to dilute the lubricating oil and aggravate the wear between the piston and the cylinder wall.

[0005] (2) Methanol has the characteristics of low saturated vapor pressure and high latent heat of vaporization. Liquid methanol is difficult to evaporate, which will cause starting difficulties when the engine is cold. When methanol is injected into the cylinder and evaporates, it will absorb a large amount of heat in the cylinder, which will affect the engine's performance at low load and low speed.

[0006] (3) Methanol itself is toxic, which puts stricter requirements on its storage, transportation and use. Ingestion or inhalation of excessive methanol vapor can cause poisoning.

[0007] (4) Compared with diesel engines, methanol engines produce unconventional emissions, such as unburned methanol and formaldehyde generated from incomplete combustion. These emissions are harmful to human health and the environment.

[0008] Currently, a commonly used technology in marine engine manufacturing is diesel and methanol dual-fuel technology. This involves injecting diesel and methanol separately into the engine for combustion. Diesel is injected directly into the cylinder, while methanol is injected through the intake manifold. Air and methanol mix in the intake manifold before entering the cylinder, where diesel fuel ignites the methanol mixture pre-installed in the cylinder. This technology requires simultaneous control of both methanol and diesel fuel injection and is widely used and mature in marine engine manufacturing. However, its drawbacks include a complex engine structure and the need to store both methanol and diesel fuels. Furthermore, methanol has a high auto-ignition temperature, making it difficult to burn completely in the cylinder, especially during cold starts, leading to starting and running difficulties. Due to the combustion characteristics of methanol and the complexity of the engine's operating environment, precise control of the methanol combustion process is difficult, resulting in uneven combustion efficiency across cylinders and affecting overall engine performance. Summary of the Invention

[0009] Therefore, the present invention provides a combustion control method and system for a marine methanol engine, which can accurately control the heating process in each cylinder of the methanol engine to maintain normal combustion conditions, thus solving the problem of difficult start-up and combustion of marine methanol engines.

[0010] To solve the above-mentioned technical problems, the present invention provides a combustion control method for a marine methanol engine. The marine methanol engine includes a controller, a transformer, multiple cylinders, methanol injectors arranged corresponding to each cylinder, and heaters arranged corresponding to each cylinder. Each heater is electrically connected to the transformer. The controller controls the heating power of each heater by controlling the voltage setting of the transformer. Methanol is injected into the cylinder through the methanol injectors and mixed with air introduced into the cylinder. The resulting methanol-gas mixture is burned to perform work by the heat released by the heaters. The control method includes: The heat released by the corresponding heater in each cylinder and the amount of methanol injected by the corresponding methanol injector are obtained, and the initial temperature of methanol before entering the methanol injector is obtained. Obtain the total intake air volume and intake air temperature of the marine methanol engine; Based on the methanol injection quantity, the total intake volume, the intake temperature, and the initial temperature, the heating heat required to heat the methanol mixture in each cylinder to the auto-ignition point is determined. The heating power of each heater is controlled by the transformer; In response to the release of heat being greater than or equal to the heating heat, the current heating power of the heater remains unchanged; In response to the release of heat being less than the heating heat, the heating power of the heater is increased until the release of heat is greater than or equal to the heating heat.

[0011] In one embodiment of the present invention, it further includes: Obtain the exhaust temperature of each cylinder during actual operation; The preset exhaust temperature threshold for each cylinder during operation, and the temperature fluctuation value during methanol combustion; In response to the exhaust temperature being less than the difference between the exhaust temperature threshold and the temperature fluctuation value, the heating power of the heater is increased.

[0012] In one embodiment of the present invention, the temperature fluctuation value is 20°C.

[0013] In one embodiment of the invention, the heater releases heat Q A The calculation is as follows: ; in, U This refers to the heating voltage output from the transformer to each heater, expressed in volts (V). R The resistance of each heater is expressed in Ω. t Heating time, measured in seconds; heat released. Q A The unit is J.

[0014] In one embodiment of the present invention, the amount of heat required to heat the methanol mixture in each of the cylinders to its auto-ignition point is [not specified]. Q B The calculation is as follows: ; Where c0 is the latent heat of vaporization of methanol, in J / kg, which is the heat required for a unit mass of methanol to change from liquid to gas. q represents the amount of methanol injected per unit time in each cylinder, in kg. 64.7 is the boiling point of methanol, in °C. t8 is the initial temperature of methanol before it enters the methanol injector, in °C; c1 is the specific heat capacity of methanol vapor at 65℃, in J / kg·℃; t7 is the air temperature entering each cylinder, in °C; c2 is the specific heat capacity of air at temperature t7, expressed in J / kg·℃; q7 represents the total intake air volume, in kg. n Let q be the number of cylinders in a marine methanol engine, with each cylinder receiving an average amount of air, and the intake air volume for each cylinder being q7 / n.

[0015] The present invention also provides a combustion control system for a marine methanol engine, comprising: The parameter acquisition module is used to acquire the heat released by the corresponding heater in each cylinder, the amount of methanol injected by the methanol injector, the initial temperature of methanol before entering the methanol injector, and the total intake air volume and intake air temperature of the marine methanol engine. The heating heat acquisition module is used to determine the heating heat required to heat the methanol mixture in each cylinder to the auto-ignition point based on the methanol injection amount, the total intake air volume, the intake air temperature, and the initial temperature. A heating power adjustment module is used to control the heating power of each heater through the transformer; in response to the released heat being greater than or equal to the heating heat, the current heating power of the heater remains unchanged; in response to the released heat being less than the heating heat, the heating power of the heater is increased until the released heat is greater than or equal to the heating heat.

[0016] The technical solution of the present invention has the following advantages compared with the prior art: The present invention discloses a combustion control method and system for a marine methanol engine. By using a controller to precisely adjust the heating power of the heaters in each cylinder, the mixture of methanol and air can be heated to its auto-ignition point, thereby achieving stable combustion of methanol and solving the problem of difficult methanol combustion.

[0017] Multiple sensors are used to monitor intake air temperature, methanol temperature, and exhaust temperature of each cylinder in real time to ensure normal combustion in each cylinder. By preset exhaust temperature thresholds and controlling temperature fluctuation ranges, the heater power is further precisely adjusted to prevent incomplete combustion or abnormal temperature. Attached Figure Description

[0018] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0019] Figure 1 This is a flowchart of the combustion control method for a marine methanol engine according to the present invention.

[0020] Figure 2 This is a schematic diagram of the methanol engine principle in Embodiment 2 of the present invention. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0022] In this invention, when directions (up, down, left, right, front, and back) are described, it is only for the convenience of describing the technical solution of this invention, and does not indicate or imply that the technical features referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0023] In this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," "exceeding," etc., are understood to exclude the stated number; "above," "below," "within," etc., are understood to include the stated number. In the description of this invention, the terms "first" and "second" are used only to distinguish technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0024] In this invention, unless otherwise explicitly defined, the terms "setting," "installing," and "connecting" should be interpreted broadly. For example, they can refer to a direct connection or an indirect connection through an intermediate medium; a fixed connection, a detachable connection, or an integrally formed connection; a mechanical connection, an electrical connection, or a connection capable of mutual communication; or the internal connection of two components or the interaction between two components. Those skilled in the art can reasonably determine the specific meaning of the above terms in this invention based on the specific content of the technical solution.

[0025] Example 1 Reference Figure 1 As shown, this embodiment provides a combustion control method for a marine methanol engine, applied to a marine methanol engine. The marine methanol engine includes a controller, a transformer, multiple cylinders, methanol injectors arranged corresponding to each cylinder, and heaters arranged corresponding to each cylinder. Each heater is electrically connected to the transformer. The controller controls the heating power of each heater by controlling the gear selection of the transformer. Methanol is injected into the cylinder through the methanol injectors and mixed with the air introduced into the cylinder. The resulting methanol mixture is burned to do work by the heat released by the heaters.

[0026] The control method includes: S1. Obtain the heat released by the corresponding heater in each cylinder, and the amount of methanol injected by the corresponding methanol injector, and obtain the initial temperature of methanol before entering the methanol injector. Obtain the total intake air volume and intake air temperature of the marine methanol engine; S2. Based on the methanol injection quantity, the total intake volume, the intake temperature, and the initial temperature, determine the heating heat required to heat the methanol mixture in each cylinder to its auto-ignition point. S3. Control the heating power of each heater through the transformer; S4. In response to the released heat being greater than or equal to the heated heat, the current heating power of the heater remains unchanged; S5. In response to the released heat being less than the heated heat, increase the heating power of the heater until the released heat is greater than or equal to the heated heat.

[0027] To monitor the operating status of each cylinder and ensure that methanol in each cylinder can burn normally and produce power, the control method further includes: Obtain the exhaust temperature of each cylinder during actual operation; The preset exhaust temperature threshold for each cylinder during operation, and the temperature fluctuation value during methanol combustion; In response to the exhaust temperature being less than the difference between the exhaust temperature threshold and the temperature fluctuation value, the heating power of the heater is increased.

[0028] Specifically, the heater releases heat Q A The calculation is as follows: ; in, U This refers to the heating voltage output from the transformer to each heater, expressed in volts (V). R The resistance of each heater is expressed in Ω. t Heating time, measured in seconds; heat released. Q A The unit is J.

[0029] Specifically, the amount of heat required to heat the methanol mixture in each cylinder to its auto-ignition point. Q B The calculation is as follows: ; Where c0 is the latent heat of vaporization of methanol, in J / kg, which is the heat required for a unit mass of methanol to change from liquid to gas. q represents the amount of methanol injected per unit time in each cylinder, in kg. 64.7 is the boiling point of methanol, in °C. t8 is the initial temperature of methanol before it enters the methanol injector, in °C; c1 is the specific heat capacity of methanol vapor at 65℃, in J / kg·℃; t7 is the air temperature entering each cylinder, in °C; c2 is the specific heat capacity of air at temperature t7, expressed in J / kg·℃; q7 represents the total intake air volume, in kg. n Let q be the number of cylinders in a marine methanol engine, with each cylinder receiving an average amount of air, and the intake air volume for each cylinder being q7 / n.

[0030] Through the above control methods, precise combustion control of methanol was achieved by accurately controlling the heating power of each cylinder, under the premise that the engine operates on methanol as the sole fuel, thus solving the problem of difficult starting and combustion of marine methanol engines.

[0031] Example 2 In this embodiment, refer to Figure 2 The diagram shows the principle of a methanol engine. The engine is an inline six-cylinder engine. The intake air temperature sensor T7 and the intake air flow sensor Q7 are respectively arranged on the engine intake manifold. Intake air temperature sensor T7 and intake air flow sensor Q7 are used to measure the total intake air volume and intake air temperature of the engine, respectively, and transmit the signals to the controller through the wiring harness. Methanol injectors J1-J6 are arranged for each cylinder. The methanol injection quantity of each cylinder is controlled by the controller to execute the methanol injector. The controller controls the methanol pump to draw methanol from the methanol tank and increase the methanol pressure, and injects the methanol directly into the cylinder through the methanol injector. Methanol temperature sensor T8 is arranged in the methanol tank. Heaters H1-H6 are arranged corresponding to each cylinder, powered by a 24V power supply connected to a transformer. The transformer has six interfaces (1-6), controlling the voltage output of the heaters in cylinders 1-6. Each interface of the transformer has five settings (a / b / c / d / e): setting a is 24V output, setting b is 100V output, setting c is 200V output, setting d is 300V output, and setting e is 400V output. The transformer setting is controlled by a controller. The heaters in each cylinder are connected to the transformer output. The controller controls the voltage input of the heaters in all six cylinders by adjusting the transformer setting for each cylinder. Exhaust temperature sensors T1-T6 are installed at the exhaust outlet of each cylinder to measure the exhaust temperature.

[0032] When the engine is running, the controller collects the exhaust temperature t1-t6, intake air temperature t7, and methanol temperature t8 of each cylinder through sensors T1-T8, and measures the total intake air volume q7 through the intake air flow sensor Q7. Combined with the set injection volume q1-q6 of each methanol injector, the controller calculates the amount of heat required to heat the mixture of methanol and air injected into each cylinder to its auto-ignition point. Then, by adjusting the voltage setting of the control transformer, the controller adjusts the heating power of the heater to ensure that the heater releases a certain amount of heat per unit time. Q A The amount of heat required to heat the methanol mixture to its auto-ignition point is higher than the amount of heat required to heat the mixture. QB This allows methanol to burn and perform work within the cylinder.

[0033] Taking cylinder number 1 as an example, the heat released by the heater corresponding to cylinder number 1 is: ; Where U1 is the heating voltage output from the transformer to cylinder 1, R is the resistance of the heater in cylinder 1, and t is the heating time. The calculation method for the heat released by the heaters in cylinders 2-6 is the same.

[0034] The amount of heat required to heat the methanol mixture in cylinder 1 to its auto-ignition point Q B1 The calculation is as follows: ; Where c0 is the latent heat of vaporization of methanol, in J / kg, which is the heat required for a unit mass of methanol to change from liquid to gas. q1 is the amount of methanol injected per unit time in cylinder 1, in kg; 64.7 is the boiling point of methanol, in °C. t8 is the initial temperature of methanol before it enters the methanol injector (i.e., the methanol temperature inside the methanol tank), in °C. c1 is the specific heat capacity of methanol vapor at 65℃, in J / kg·℃; t7 is the air temperature entering each cylinder, in °C; c2 is the specific heat capacity of air at temperature t7, expressed in J / kg·℃; q7 represents the total intake air volume, in kg. The intake volume of cylinder 1 is q7 / 6.

[0035] When the controller calculates Q A1 ≥ Q B1 If so, maintain the current gear selection for the heater in transformer cylinder 1. Q A1 < Q B1 When this happens, the controller adjusts the heater setting in cylinder 1 to a higher voltage setting until it reaches the specified voltage. Q A1 ≥ Q B1 The calculation and control methods for cylinders 2-6 are the same as those for cylinder 1.

[0036] To monitor the operating status of each cylinder and ensure that methanol in cylinders 1-6 burns and produces power normally, exhaust temperature sensors T1-T6 are installed at the exhaust ports of cylinders 1-6 to collect the exhaust temperatures t1-t6 of each of the six cylinders. Taking cylinder 1 as an example, when the methanol injection quantity is q1 and the intake quantity is (q7 / 6), the exhaust temperature of cylinder 1 under normal operating conditions is t1 / t6. n1 , will t n The controller is calibrated to the normal operating limits. Temperature fluctuations during methanol combustion generally do not exceed 20°C. When the controller detects t1 < (t... n1 When the temperature is -20℃, the controller will adjust the heating level of cylinder 1 to a higher voltage level to provide greater heating power and ensure that the methanol in cylinder 1 burns normally.

[0037] By utilizing multiple sensors to monitor intake air temperature, methanol temperature, and exhaust temperature of each cylinder in real time, normal combustion in each cylinder is ensured. Furthermore, by preset exhaust temperature thresholds and controlling temperature fluctuation ranges, the heater power is precisely adjusted to prevent incomplete combustion or abnormal temperatures.

[0038] Example 3 Based on the same inventive concept, this embodiment provides a combustion control system for a marine methanol engine. The principle of solving the problem is similar to that of the aforementioned combustion control method for a marine methanol engine, and the repeated parts will not be described again.

[0039] This embodiment provides a combustion control system for a marine methanol engine, including: The parameter acquisition module is used to acquire the heat released by the corresponding heater in each cylinder, the amount of methanol injected by the methanol injector, the initial temperature of methanol before entering the methanol injector, and the total intake air volume and intake air temperature of the marine methanol engine. The heating heat acquisition module is used to determine the heating heat required to heat the methanol mixture in each cylinder to the auto-ignition point based on the methanol injection amount, the total intake air volume, the intake air temperature, and the initial temperature. A heating power adjustment module is used to control the heating power of each heater through the transformer; in response to the released heat being greater than or equal to the heating heat, the current heating power of the heater remains unchanged; in response to the released heat being less than the heating heat, the heating power of the heater is increased until the released heat is greater than or equal to the heating heat.

[0040] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0041] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0042] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0043] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0044] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for controlling combustion of a marine methanol engine, characterized in that: The marine methanol engine comprises a controller, a transformer, a plurality of cylinders, a methanol injector arranged corresponding to each cylinder, and a heater arranged corresponding to each cylinder, each of the heaters is electrically connected to the transformer, the controller controls the gear selection of the transformer to control the heating power of each heater, methanol is sprayed into the cylinder through the methanol injector and mixed with the air introduced into the cylinder, and the obtained methanol mixed gas is burned to do work by releasing heat through the heater; The control method comprises: Obtaining the heat released by the corresponding heater in each cylinder and the amount of methanol injected by the corresponding methanol injector, and obtaining the initial temperature of the methanol before entering the methanol injector; Obtaining the total amount of air intake and the intake temperature of the marine methanol engine; Determining the heating amount required to heat the methanol mixture in each cylinder to the auto-ignition point based on the methanol injection amount, the total intake air amount, the intake air temperature and the initial temperature; Controlling the heating power of each of the heaters through the transformer; In response to the released heat being greater than or equal to the heated heat, maintaining the current heating power of the heater unchanged; In response to the released heat being less than the heated heat, the heating power of the heater is increased until the released heat is greater than or equal to the heated heat.

2. A marine methanol engine combustion control method according to claim 1, characterized in that: Also includes: Obtaining the exhaust temperature of each cylinder when it is actually working; Presetting the exhaust temperature threshold value when each cylinder is working, and the temperature fluctuation value when methanol is burning; In response to the exhaust temperature being less than a difference between the exhaust temperature threshold and the temperature fluctuation value, a heating power of the heater is increased.

3. A marine methanol engine combustion control method according to claim 2, characterized in that: The temperature fluctuation value is 20°C.

4. A marine methanol engine combustion control method according to claim 1, characterized in that: The heater releases heat Q A The calculation is as follows: ； in, U It is the heating voltage output by the transformer to each heater, in V; R is the resistance of each heater, in Ω; t is the heating time, in seconds; the heat released Q A The unit is J.

5. A marine methanol engine combustion control method according to claim 1, characterized in that: The heating amount required to heat the methanol mixed gas in each cylinder to the auto-ignition point Q B The calculation is as follows: ； Where c0 is the latent heat of vaporization of methanol, in J / kg, which is the heat required for a unit mass of methanol to change from liquid to gas; q is the amount of methanol injected per unit time in each cylinder, in kg; 64.7 is the boiling point of methanol, in °C; t8 is the initial temperature of methanol before entering the methanol injector, in °C; c1 is the specific heat capacity of methanol vapor at 65°C, in J / kg·°C; t7 is the temperature of the air entering each cylinder, in °C; c2 is the specific heat capacity of air at temperature t7, in J / kg·℃; q7 is the total intake air volume, in kg; n is the number of cylinders in the marine methanol engine. The air volume is evenly distributed in each cylinder, and the air intake volume of each cylinder is q7 / n.

6. A marine methanol engine combustion control system, characterized in that: A marine methanol engine combustion control method according to any one of claims 1 to 5, comprising: A parameter acquisition module is used to obtain the heat released by the corresponding heater in each cylinder, the amount of methanol injected by the methanol injector, the initial temperature of the methanol before entering the methanol injector, and the total amount of air intake and the intake temperature of the marine methanol engine; A heating heat acquisition module, used for determining the heating heat required to heat the methanol mixed gas in each cylinder to the auto-ignition point based on the methanol injection amount, the total intake air amount, the intake air temperature and the initial temperature; A heating power adjustment module is used to control the heating power of each of the heaters through the transformer; in response to the released heat being greater than or equal to the heating heat, keep the current heating power of the heater unchanged; in response to the released heat being less than the heating heat, increase the heating power of the heater until the released heat is greater than or equal to the heating heat.

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