Methanol independent preheating system and method for realizing fuel evaporation and inlet air heating

Abstract

The invention discloses an independent methanol preheating system capable of realizing fuel evaporation and inlet air heating, relates to a methanol engine, and solves the technical problems that an existing boiler heating scheme is long in starting time and large in methanol consumption, and a vehicle-mounted storage battery cannot provide enough output power. Comprising a first methanol nozzle, a heating plug and a second methanol nozzle, the first methanol nozzle, the heating plug and the second methanol nozzle are sequentially arranged in a common rail pipe, one end of the common rail pipe is communicated with an air inlet header pipe, and the system further comprises a fire retardant net and a combustion layer for promoting stable combustion of methanol fuel. The combustion layer is installed between the first methanol nozzle and the heating plug, and the fire-retardant net is installed between the second methanol nozzle and the heating plug. The invention also discloses a methanol independent preheating method for realizing fuel evaporation and inlet air heating. The air inlet temperature can be remarkably improved, and the success rate of cold start of the methanol engine is increased.

Description

Technical Field

[0001] This invention relates to methanol engines, and more specifically, to a methanol independent preheating system and method for achieving fuel evaporation and intake air heating. Background Technology

[0002] like Figure 1 As shown, by heating the engine's cooling water in a boiler, it usually takes about 30 minutes at -35℃ to raise the engine's cooling water temperature to above 50℃. The temperature of the engine cylinder head and body is also close to that temperature, allowing the methanol engine to be started directly.

[0003] In addition, numerous researchers have studied the effects of methanol fuel droplet enhanced evaporation and methanol engine intake air heating on improving methanol cold starting. 1) Methanol fuel droplet enhanced evaporation involves injecting methanol onto a PTC heating element, where the methanol droplets rapidly boil and vaporize under the high temperature of the PTC heating element; 2) Methanol engine intake air heating typically involves installing an intake grille heater in the intake manifold to heat the engine's intake system. These measures can all improve the cold starting of methanol engines, but due to limitations in battery power supply, ultra-high-power electric heating measures cannot be used, thus the improvement effect is extremely limited. This study analyzed a 15L methanol engine and found that to increase the air temperature during starting and completely vaporize the methanol, an electric heating power of approximately 8kW is required, corresponding to a battery current demand exceeding 300A, which the onboard battery cannot meet.

[0004] (1) Although the boiler heating scheme has been widely used in the market and can effectively achieve cold start of methanol engine at low temperature of -35℃, it takes a long time. It requires more than 30 minutes in advance to preheat the cooling water of methanol engine, resulting in a long start-up time and a large amount of methanol consumed.

[0005] (2) The scheme of using electric heating technology to promote the vaporization of methanol droplets and heat the air is not feasible for mass production because the vehicle battery cannot provide sufficient output power. Because methanol has a large latent heat of vaporization, for a 15L methanol engine, the methanol vaporization power during the starting process is as high as 4kW, and the air heating power requirement is as high as 4kW. It is necessary to maintain an accessory power consumption of 8kW for a long time, which ordinary vehicle batteries cannot meet. Therefore, it is limited to the laboratory research stage. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an independent methanol preheating system and method for realizing fuel evaporation and intake air heating, which addresses the shortcomings of the existing boiler heating schemes, such as long start-up time, large methanol consumption, and insufficient output power provided by the vehicle battery.

[0007] The present invention discloses an independent methanol preheating system for achieving fuel evaporation and intake air heating, comprising a first methanol nozzle, a heating plug, and a second methanol nozzle. The first methanol nozzle, the heating plug, and the second methanol nozzle are sequentially arranged in a common rail, one end of which is connected to the intake manifold. The system also includes a flame arrester and a combustion layer for promoting stable combustion of methanol fuel. The combustion layer is installed between the first methanol nozzle and the heating plug, and the flame arrester is installed between the second methanol nozzle and the heating plug.

[0008] As a further improvement, the first methanol nozzle is oriented towards the combustion layer.

[0009] Furthermore, the second methanol nozzle is oriented towards the flame arrestor mesh, and the angle between the second methanol nozzle and the inner wall of the common rail is 45°.

[0010] Furthermore, the combustion layer is a porous combustion mesh or combustion cotton.

[0011] Furthermore, the fire-retardant mesh is made of metal.

[0012] Furthermore, the fire-resistant mesh has a mesh count of 16 to 22.

[0013] A method for using the aforementioned methanol independent preheating system to achieve fuel evaporation and intake air heating functions includes the following steps: Before starting the engine, firstly, the heating plug is turned on to preheat the combustion screen; then, the first throttle valve installed in the intake manifold is closed, and the second throttle valve installed at the connection between the intake manifold and the common rail is opened, setting the opening of the second throttle valve to a preset first opening; simultaneously, the engine is started, and the first methanol nozzle is turned on to inject methanol fuel onto the preheated combustion screen; the second methanol nozzle is turned on to inject methanol fuel onto the flame arrestor screen; the exhaust flow rate is obtained, and the opening of the second throttle valve is set according to the exhaust flow rate; the real-time engine coolant temperature is obtained, and when the real-time coolant temperature is equal to a preset coolant temperature threshold, the first methanol nozzle, the second methanol nozzle, and the second throttle valve are closed.

[0014] As a further improvement, the preheating time for the combustion mesh is 1 minute.

[0015] Furthermore, the water temperature threshold is 50°C.

[0016] Furthermore, when the first methanol nozzle is opened to inject methanol fuel into the preheated combustion grid, the heating plug is closed.

[0017] Beneficial effects The advantages of this invention are: 1. This invention, by setting up a flame arrestor and a combustion layer that promotes stable combustion of methanol fuel, with the combustion layer installed between the first methanol nozzle and the heating plug, and the flame arrestor installed between the second methanol nozzle and the heating plug, allows methanol to be sprayed onto the high-temperature flame arrestor, ensuring sufficient contact between methanol droplets and the flame arrestor surface, thus enhancing methanol evaporation and vaporization. The flame arrestor prevents further flame spread. By spraying methanol onto the high-temperature flame arrestor, ensuring sufficient contact between methanol droplets and the flame arrestor surface, the evaporation and vaporization of methanol is enhanced, thereby constructing a methanol combustion chamber in front of the flame arrestor. This utilizes the chemical energy released from the combustion of methanol to heat the engine intake air and vaporize more methanol, eliminating the need for electrical energy to heat the air and methanol droplets, significantly reducing the current demand on the battery, significantly improving intake air temperature, and increasing the success rate of cold starting the methanol engine.

[0018] 2. This invention integrates the flame arrestor mesh, combustion layer, first methanol nozzle, second methanol nozzle, and heating plug within a common rail, which is arranged in parallel with the intake manifold. No heating measures are installed on the intake manifold itself. The intake path is switched by controlling two throttle valves. Air flows through this heating module only during cold starts; during normal operation, air does not pass through it. Compared to traditional electric heating grilles, this module significantly reduces intake resistance during normal engine operation, thereby improving engine performance. Attached Figure Description

[0019] Figure 1 This is a schematic diagram illustrating the application of existing boiler heating technology in the cold start of a methanol engine. Figure 2 This is a structural diagram of the methanol independent preheating system of the present invention.

[0020] Wherein: 1-First methanol nozzle, 2-Heating plug, 3-Combustion layer, 4-Flame arrestor mesh, 5-Second methanol nozzle, 6-Common rail, 7-First throttle valve, 8-Second throttle valve, 9-Intake manifold. Detailed Implementation

[0021] The present invention will be further described below with reference to embodiments, but this does not constitute any limitation on the present invention. Any limited modifications made by any person within the scope of the claims of the present invention are still within the scope of the claims of the present invention. See Figure 2The present invention discloses an independent methanol preheating system for realizing fuel evaporation and intake air heating, comprising a first methanol nozzle 1, a heating plug 2, and a second methanol nozzle 5. The first methanol nozzle 1, the heating plug 2, and the second methanol nozzle 5 are sequentially arranged in a common rail pipe 6, one end of which is connected to the intake manifold 9. The system also includes a flame arrester 4 and a combustion layer 3 for promoting stable combustion of methanol fuel. The combustion layer 3 is installed between the first methanol nozzle 1 and the heating plug 2, and the flame arrester 4 is installed between the second methanol nozzle 5 and the heating plug 2.

[0022] The first methanol nozzle 1 faces the combustion layer 3. This allows the first methanol nozzle 1 to evenly spray methanol fuel onto the preheated combustion layer 3.

[0023] The second methanol nozzle 5 is oriented towards the flame arrestor mesh 4, and the angle between the second methanol nozzle 5 and the inner wall of the common rail pipe 6 is 45°. By optimizing the injection angle and direction, the jet formed after methanol atomization can make more full contact with the flame arrestor mesh, thereby effectively reducing the risk of flame propagation and ensuring maximum combustion efficiency.

[0024] The combustion layer is a porous combustion mesh or combustion cotton. Using porous combustion mesh or combustion cotton promotes stable combustion of liquid fuels. This is because porous media have a huge internal surface area. When fuel droplets collide with and diffuse onto these surfaces, an extremely thin liquid film is formed, increasing the contact area between the fuel and the high-temperature solid by thousands of times, resulting in an exponential increase in the evaporation rate. Furthermore, porous media themselves have heat storage capabilities, continuously absorbing heat from the flame to maintain a stable high-temperature zone, continuously providing the heat required for the evaporation of fresh liquid fuel, thereby achieving continuous gasification and combustion of the fuel.

[0025] The flame arrestor mesh is made of metal or other flame-arresting materials such as ceramics. The mesh size is 16-22 mesh. The flame arrestor mesh consists of numerous long, narrow channels that quench the flame and prevent its downstream propagation. When combustible gas passes through these narrow channels, the probability of free radicals colliding with the channel walls increases significantly (the smaller the channel diameter, the higher the collision frequency), causing the free radical destruction rate to exceed the formation rate. When the channel size is smaller than the critical quenching diameter (2.5mm-3.5mm for methanol), the number of free radicals decreases sharply, and the combustion reaction cannot continue. This flame arrestor mesh employs a multi-layered, staggered structure, allowing free radicals to be consumed through interlayer collisions, thus achieving flame quenching.

[0026] Methanol is sprayed onto a high-temperature flame arrestor, ensuring full contact between the methanol droplets and the flame arrestor surface. This enhances the evaporation and vaporization of the methanol. The flame arrestor prevents further flame spread. By spraying methanol onto the high-temperature flame arrestor surface, the methanol droplets fully contact the flame arrestor surface, enhancing the evaporation and vaporization of the methanol. This creates a methanol combustion chamber in front of the flame arrestor, utilizing the chemical energy released from the combustion of methanol to heat the engine intake air and vaporize more methanol. This eliminates the need for electrical energy to heat the air and methanol droplets, significantly reducing the current demand on the battery, significantly improving intake air temperature, and increasing the success rate of cold starts for methanol engines.

[0027] A method for using the aforementioned methanol independent preheating system that achieves fuel evaporation and intake air heating functions, wherein the method involves activating the heating plug 2 before starting the engine to preheat the combustion layer 3. The preheating time for the combustion layer 3 is 1 minute. This 1-minute preheating time can raise the temperature of the combustion layer 3 to over 800°C. The power of the heating plug 2 is approximately 400W.

[0028] Then, close the first throttle valve 7 installed in the intake manifold 9, and open the second throttle valve 8 installed at the connection between the intake manifold 9 and the common rail 6. Set the opening of the second throttle valve 8 to the preset first opening. Simultaneously, start the engine and open the first methanol injector 1 to inject methanol fuel onto the preheated combustion layer 3, allowing the methanol to achieve surface combustion on the mesh surface of the combustion layer 3. The heat released by combustion can significantly increase the intake air temperature, and the heat is also transferred to the combustion layer 3. When the first methanol injector 1 is opened to inject methanol fuel onto the preheated combustion layer 3, the heater plug 2 is closed. The combustion layer 3 can also maintain a high temperature under the radiative heat transfer of the flame. The flame will be extinguished after passing through the flame arrestor 4, while the temperature of the flame arrestor 4 will increase. The air temperature is further increased when the air passes through the flame arrestor 4.

[0029] The second methanol nozzle 5 is opened to inject methanol fuel onto the flame arrestor 4. Under the combined action of the high-temperature air and the high-temperature flame arrestor 4, the methanol injected from the second methanol nozzle 5 rapidly vaporizes and mixes evenly with the air.

[0030] The mixture of methanol vapor and air flows through the second throttle valve 8, and then enters each cylinder through the intake manifold, ultimately enabling the methanol engine to ignite normally. Exhaust flow rate is obtained by an oxygen sensor installed in the engine exhaust pipe, and the opening of the second throttle is set according to the exhaust flow rate. This method of setting the opening is a mature existing technology and can be calibrated based on experimental data. This adjusts the second throttle valve 8 to control the actual airflow entering the cylinder, maintaining the stoichiometric ratio of the air-fuel mixture within the range of 1 to 1.5.

[0031] The engine's real-time coolant temperature is acquired. When the real-time coolant temperature equals a preset coolant temperature threshold, the first methanol injector 1, the second methanol injector 5, and the second throttle valve 8 are closed. The coolant temperature threshold is 50°C. Finally, the engine performs fuel injection and controls the first throttle valve 7 according to normal operating conditions.

[0032] The intake path is switched by adjusting two throttle valves. Air flows through the heating module only during cold starts; during normal operation, air does not pass through this module. Compared with traditional electric heating grilles, this module can significantly reduce intake resistance during normal engine operation, thereby improving engine performance.

[0033] For ease of understanding, the following analysis uses a 15L methanol engine as an example to illustrate the cold start process at -35℃: Because the temperature of the engine's intake manifold, intake port, cylinder head, cylinder liners, and piston walls is the same as the ambient temperature (-35°C), the heated, high-temperature air absorbs heat from these walls as it passes through, causing its temperature to drop rapidly. Unlike traditional gasoline and diesel engines, methanol is difficult to ignite at low temperatures. Based on experience, the engine's intake air must be heated to above 60°C to ensure the methanol engine can start normally.

[0034] The following is an analysis of the traditional electric heating mode: During the start-up process of the methanol engine, the ambient temperature is -35℃, the intake air flow rate is 50 kg / h (i.e., 0.01389 kg / s), and the methanol fuel consumption is 8 kg / h (i.e., 0.002222 kg / s). The power estimates for air heating and methanol vaporization are as follows: Air heating power: air specific heat capacity C p Approximately 1 kJ / kg·K; temperature difference ΔT = 60℃ - (-35℃) = 95℃; traditional air intake grilles, in order to reduce intake resistance, have extremely limited contact between the heating elements and the air, resulting in low heating efficiency. Extremely low, typically only 30%. In summary, the power of the air heater can be calculated. P heat1 : Methanol vaporization power consumption P heat2 The total heat absorption Q of methanol vaporization and heating to 50°C is 1349 kJ / kg, specifically including: 249 kJ / kg of liquid methanol absorbed from -35°C to its boiling point of 60°C, and 1100 kJ / kg of latent heat of the gas. The heating efficiency of the methanol vaporization process is... The efficiency is 75%. Therefore, the methanol vaporization power consumption is calculated as follows: P heat2 : .

[0035] Battery current: For heavy commercial vehicles, the battery is typically 24V, therefore the current I = 8000W / 24V = 333A. Traditional vehicle batteries cannot meet this requirement.

[0036] The following is an example of the methanol independent preheating system of the present invention. By comparing it with the above-mentioned traditional electric heating mode analysis method, a significant improvement effect is obtained.

[0037] Example 1: Analysis of the heating mode of this patent The amount of methanol required for air heating The lower heating value (LHV) of methanol is approximately 20.0 MJ / kg. To achieve a heat release of 8 kW, the required methanol flow rate is 8 kJ / s ÷ 20,000 kJ / kg = 0.0004 kg / s = 1.44 kg / h.

[0038] Battery current: The heating plug has a power of 400W, corresponding to a current of 400W / 24V=16.7A, which can be met by a regular vehicle battery.

[0039] This patent uses the chemical energy generated by the combustion of methanol at a rate of 1.44 kg / h to heat the air and vaporize the methanol, which greatly reduces the power demand on the battery.

[0040] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention, and these will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A methanol independent preheating system for realizing fuel evaporation and intake air heating, comprising a first methanol nozzle (1), a heating plug (2), and a second methanol nozzle (5), wherein the first methanol nozzle (1), the heating plug (2), and the second methanol nozzle (5) are sequentially arranged in a common rail (6), one end of the common rail (6) being connected to the intake manifold (9), characterized in that, The system also includes a flame arrestor (4) and a combustion layer (3) that promotes stable combustion of methanol fuel. The combustion layer (3) is installed between the first methanol nozzle (1) and the heating plug (2), and the flame arrestor (4) is installed between the second methanol nozzle (5) and the heating plug (2).

2. The methanol independent preheating system for realizing fuel evaporation and intake air heating according to claim 1, characterized in that, The first methanol nozzle (1) faces the combustion layer (3).

3. The methanol independent preheating system for realizing fuel evaporation and intake air heating according to claim 1, characterized in that, The second methanol nozzle (5) faces the flame arrestor mesh (4), and the angle between the second methanol nozzle (5) and the inner wall of the common rail pipe (6) is 45°.

4. The methanol independent preheating system for realizing fuel evaporation and intake air heating according to claim 1, characterized in that, The combustion layer (3) is a porous combustion mesh or combustion cotton.

5. A methanol independent preheating system for realizing fuel evaporation and intake air heating according to claim 1, characterized in that, The fire-resistant mesh is made of metal.

6. The methanol independent preheating system for realizing fuel evaporation and intake air heating according to claim 1, characterized in that, The fire-resistant mesh has a mesh size of 16 to 22.

7. A method for using a methanol independent preheating system according to any one of claims 1-6 to achieve fuel evaporation and intake air heating functions, characterized in that, The method is as follows: before starting the engine, first turn on the heating plug (2) to preheat the combustion layer (3); then close the first throttle valve (7) installed in the intake manifold (9), open the second throttle valve installed at the connection between the intake manifold (9) and the common rail (6), set the opening of the second throttle valve (8) to a preset first opening, start the engine, open the first methanol nozzle (1) to inject methanol fuel onto the preheated combustion layer (3); open the second methanol nozzle (5) to inject methanol fuel onto the flame arrestor (4); obtain the exhaust flow rate, set the opening of the second throttle valve according to the exhaust flow rate; obtain the real-time water temperature of the engine, and when the real-time water temperature is equal to the preset water temperature threshold, close the first methanol nozzle (1), the second methanol nozzle (5) and the second throttle valve (8).

8. The methanol independent preheating method for achieving fuel evaporation and intake air heating according to claim 7, characterized in that, The preheating time for the combustion layer (3) is 1 minute.

9. A method for independent preheating of methanol to achieve fuel evaporation and intake air heating according to claim 7, characterized in that, The water temperature threshold is 50℃.

10. A method for independently preheating methanol to achieve fuel evaporation and intake air heating according to claim 7, characterized in that, When the first methanol nozzle (1) is opened to inject methanol fuel into the preheated combustion layer (3), the heating plug (2) is closed.

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