Methanol engine cold start system based on pulse plasma catalytic combustion

Abstract

The utility model discloses a kind of methanol engine cold start system and method based on pulse plasma catalytic combustion, including gas mixer, methanol engine, pulse plasma catalytic combustor and reflux pump;The gas mixer inlet section accesses air, throat section accesses methanol, and outlet end is equipped with electric control proportional valve;The outlet end of the gas mixer is connected to methanol engine and pulse plasma catalytic combustor respectively by electric control tee valve;The pulse plasma catalytic combustor is equipped with plasma zone and catalytic zone inside;The inlet of the pulse plasma catalytic combustor is connected with the outlet end of gas mixer, and outlet is connected with reflux pump, and reflux to the throat section of gas mixer.The utility model is excited by pulse plasma body, and synergizes with catalyst, reduces reaction activation energy, so that methanol mixed gas can be excited at low temperature, produce 60-70 ℃ heating gas, provide necessary heat for engine start, without relying on external energy source, realize complete autonomous start.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of cold start of methanol engine, especially to a kind of methanol engine cold start system based on pulse plasma catalytic combustion. BACKGROUND

[0002] As a potential alternative fuel, methanol has attracted much attention due to its high octane rating and excellent clean emission characteristics. The pollutant emissions generated during its combustion are significantly lower than those of traditional fossil fuels, effectively reducing environmental pollution.

[0003] However, the physical and chemical properties of methanol also pose significant challenges in practical applications, particularly in terms of starting performance in low-temperature environments. Methanol has a high latent heat of vaporization, meaning that under low-temperature conditions, its vaporization process requires the absorption of a large amount of heat, making it difficult for the fuel to quickly form a combustible mixture. Additionally, methanol has a high auto-ignition temperature, further increasing the difficulty of starting in low-temperature environments. These characteristics result in a significant decrease in starting performance for methanol fuel below -10℃, and in extreme low-temperature environments of -30℃~-40℃, reliable starting is difficult to achieve, severely limiting its application and promotion in cold regions.

[0004] To solve the problem of low-temperature starting of methanol fuel, various solutions have been proposed in existing technology. For example, by adding gasoline as an auxiliary fuel, the low freezing point and easy evaporation characteristics of gasoline are used to improve the formation conditions of the mixture, but this method requires an additional gasoline supply system, resulting in a complex fuel supply structure and reliance on gasoline, a non-renewable resource, which contradicts the development concept of methanol as a renewable fuel. For another example, a gas preheating device is used to preheat the fuel or intake system, which can improve the starting performance in low-temperature environments to some extent, but this technology requires external energy to provide preheating power and cannot achieve completely autonomous starting, limiting its applicability in scenarios lacking external energy supply.

[0005] In summary, existing technology has the shortcomings of complex structure and reliance on external energy in solving the problem of low-temperature starting of methanol fuel, making it difficult to meet the demand for autonomous and reliable starting of methanol fuel in practical applications. INVENTION CONTENTS

[0006] To solve the above problems, the utility model provides a kind of methanol engine cold start system based on pulse plasma catalytic combustion, which can be used for the autonomous cold start of methanol engine in extremely cold environment.

[0007] Therefore, the technical scheme of the utility model is: a methanol engine cold start system based on pulse plasma catalytic combustion, comprising a gas mixer, a methanol engine, a pulse plasma catalytic combustor and a reflux pump. The gas mixer is internally of a Venturi structure, the inlet section of which is connected to air, the throat section of which is connected to methanol, and the outlet end of which is provided with an electrically-controlled proportional valve; the outlet end of the gas mixer is connected to a methanol engine and a pulse plasma catalytic combustor through an electrically-controlled three-way valve respectively; The pulse plasma catalytic combustor is internally provided with a plasma zone and a catalytic zone; the plasma zone is provided with electrode plates on both sides thereof, and the catalytic zone is filled with a catalyst; the inlet of the pulse plasma catalytic combustor is connected to the outlet end of the gas mixer, and the outlet thereof is connected to a reflux pump, which is connected to the throat section of the gas mixer through a reflux pipe.

[0008] As a preferred scheme of the above scheme and on the basis of the above scheme: further comprising a temperature control module, the temperature control module comprising a temperature sensor and a PID controller, the temperature sensor being located at the mixed gas outlet port of the gas mixer and used for monitoring the temperature of the mixed gas; the PID controller being used for controlling the on-off of the electrically-controlled three-way valve and adjusting the opening degree of the electrically-controlled proportional valve.

[0009] As a preferred scheme of the above scheme and on the basis of the above scheme: the gas mixer comprises an inlet section, a contraction section, a throat section, a diffusion section and a mixing section, the inlet section being connected to air; the throat section is connected to two paths, one of which is connected to methanol and the other of which is connected to the mixed gas heated by the pulse plasma catalytic combustor; the mixing section is internally provided with multiple-stage turbulence vanes.

[0010] As a preferred scheme of the above scheme and on the basis of the above scheme: the electrically-controlled proportional valve is used for adjusting the air-methanol ratio λ, and the ratio λ is 0.8-1.4.

[0011] As a preferred scheme of the above scheme and on the basis of the above scheme: the plasma zone of the pulse plasma catalytic combustor is close to the inlet, and the catalytic zone is close to the outlet; the anode of the plasma zone is made of titanium alloy material, and the surface thereof is coated with platinum; the cathode is made of tungsten material.

[0012] As a preferred scheme of the above scheme and on the basis of the above scheme: the catalytic zone is internally provided with multiple layers of corrugated channels, and the corrugated channels are provided with a plurality of perforations; the adjacent corrugated channels are filled with foam ceramics, and the foam ceramics and the corrugated channels are communicated through the perforations.

[0013] As a preferred scheme of the above scheme and on the basis of the above scheme: the corrugated channels are divided into three sections, the surface of the first section of channels is coated with Pt / CeO2, the surface of the second section of channels is coated with Pd / ZrO2, and the surface of the third section of channels is blank.

[0014] Compared with the prior art, the utility model has the advantages of: 1. By pulse plasma excitation and gradient catalyst synergistic effect, plasma reduces the reaction activation energy, so that methanol mixed gas can be excited at low temperature, ensuring that pre-combustion can be successfully completed in extremely cold environment to produce 60-70℃ heating gas, providing necessary heat for engine start, without relying on external energy source, realizing completely autonomous start.

[0015] 2. The gas mixer adopts Venturi structure, uses Venturi effect negative pressure to suck in methanol atomized droplets, cooperates with multi-stage turbulence to form turbulent flow, so that air and methanol are mixed more uniformly; at the same time, through the electric control proportional valve, the lambda value (air-fuel ratio) is dynamically adjusted between 0.8-1.4, ensuring that the mixed gas ratio is optimal from cold start to full load process, improving combustion efficiency.

[0016] 3. The pulse plasma catalytic combustor is internally provided with multi-layer corrugated channel type perforated carrier and foam ceramic filling structure, which increases the gas-solid contact area, realizes cross mixing of main channel airflow and interlayer airflow through the cooperation of channel perforation and foam ceramic porous structure, strengthens the mass transfer effect, improves the catalytic reaction rate, shortens the pre-combustion time, and speeds up the engine start process.

[0017] 4. The temperature control module adopts PID closed loop regulation, dynamically adjusts the on-off of the electric control three-way valve and the opening of the electric control proportional valve through the temperature sensor, accurately controls the heating gas temperature at 60-70℃, avoids the influence of too high or too low temperature on the start effect, and ensures the stable operation of the system under different working conditions. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The system flowchart of the utility model; Figure 2 The structure schematic view of the gas mixer of the utility model; Figure 3 The structure schematic view of the pulse plasma catalytic combustor of the utility model; In the drawing, it is marked as: gas mixer 1, inlet section 11, contraction section 12, throat section 13, diffusion section 14, mixing section 15, turbulence blade 16, electric control proportional valve 2, electric control three-way valve 3, pulse plasma catalytic combustor 4, plasma area 41, catalytic area 42, electrode plate 43, corrugated channel 44, foam ceramic 45, Pt / CeO2 catalyst 46, Pd / ZrO2 catalyst 47, perforation 48, temperature sensor 5. DETAILED DESCRIPTION

[0019] Referring to the drawings. The methanol engine cold start system based on pulse plasma catalytic combustion described in the embodiment comprises a gas mixer, a methanol engine, a pulse plasma catalytic combustor, a reflux pump and a temperature control module.

[0020] The gas mixer 1 is internally a Venturi structure, including an inlet section 11, a contraction section 12, a throat section 13, a diffusion section 14 and a mixing section 15, the inlet section 11 of which is connected to air, the throat section 13 of which is connected to two paths, one of which is connected to methanol and the other of which is connected to mixed gas heated by the pulse plasma catalytic burner; the mixing section 15 is provided with multiple-stage turbulence vanes 16.

[0021] The gas mixer 1 adopts a Venturi induction structure to form negative pressure, inhale micro-atomized droplets (particle size <25 μm) of the methanol nozzle, and set multiple-stage turbulence vanes to form a turbulent mixing chamber, cooperate with multiple-stage turbulence to form turbulent flow, so that air and methanol are more uniformly mixed. An electric control proportional valve 2 is arranged at the outlet end of the gas mixer 1, which can adjust the air-methanol ratio to realize the adjustment of λ=0.8-1.4.

[0022] The outlet end of the gas mixer 1 is divided into two paths through an electric control three-way valve 3, one of which is normally connected to the air inlet end of the methanol engine, and the other of which is a pre-combustion loop connected to the pulse plasma catalytic burner 4.

[0023] The pulse plasma catalytic burner integrates the catalytic burner and the pulse plasma generator, has a compact structure design with a shell diameter of 60-80 mm and a total length of 250-300 mm. The pulse plasma catalytic burner 4 is provided with a plasma zone 41 and a catalytic zone 42 from the inlet to the outlet; the plasma zone 41 has a length of 20-40 mm, is provided with electrode plates 43 on both sides, has an electrode spacing of 10-15 mm, a voltage range of 10-20 kV, a frequency of 30-50 kHz, and a power setting of 80-150 W, so as to generate stable and efficient plasma and enhance the activation and rate of the reaction process. The anode of the electrode plate uses titanium alloy (Ti) material coated with platinum (Pt) to improve the high temperature resistance; the cathode uses tungsten (W) which has good electrical conductivity and high temperature resistance. The combination of pulse discharge and shock discharge is adopted to optimize the generation efficiency and stability of the plasma.

[0024] The catalytic zone 42 is provided with multiple layers of corrugated channels 44, and the corrugated channels 44 are provided with a plurality of perforations 48; the adjacent corrugated channels 44 are filled with foamed ceramic 45, and the foamed ceramic 45 is connected with the corrugated channels 44 through the perforations 48. The foamed ceramic 45 has a three-dimensional interconnected pore structure (porosity is usually >70%), and the internal channels are interconnected with the perforations 48 of the corrugated channels 44. When the main channel gas flow enters the interlayer through the perforations, a branch flow is formed in the porous network of the foamed ceramic, and after diffusion and disturbance through countless micro-channels, it returns to the main channel through other perforations, forming a cross-flow path of “main channel→foamed ceramic→main channel”, which breaks the laminar flow state in the main channel, mixes the unreacted mixed gas with the gas flow that has contacted the catalyst, and improves the overall reaction uniformity.

[0025] The corrugated channel supports gradient coating technology, that is, the corrugated channel is divided into three sections, the surface of the first section of the channel (the inlet side) is coated with a Pt / CeO2 catalyst 46, the high activity of Pt is used to start the preliminary oxidation of methanol at a low temperature (20-30°C), and CeO2 is used as a catalyst promoter to promote oxygen transfer and reduce the accumulation of formaldehyde intermediates; the surface of the second section of the channel (the middle section) is coated with a Pd / ZrO2 catalyst 47, Pd further catalyzes the deep oxidation of the intermediate product into CO2 and H2O, and the ZrO2 carrier improves the thermal stability of the catalyst; the third section of the channel adopts a blank layer (without catalyst), and the main function is to stabilize the outlet gas temperature (controlled at 60-70°C) through heat exchange to avoid the impact of high temperature on the downstream pipeline and components.

[0026] The outlet of the pulse plasma catalytic combustor 4 is connected to a backflow pump, and the backflow pump is connected to the throat section of the gas mixer through a backflow pipe, so as to send the heated gas back to the gas mixer to heat the low-temperature mixed gas.

[0027] The temperature control module includes a temperature sensor 5 and a PID controller, and adopts closed-loop negative feedback regulation to control the on-off of the electrically controlled three-way valve and adjust the opening of the electrically controlled proportional valve. The system sets the temperature to a certain value (the middle value can be taken, such as 65°C) within the range of 60-70°C, and the control target is to stabilize the temperature of the mixed gas at the inlet of the engine around the set value.

[0028] The temperature sensor is installed at the inlet of the methanol engine to measure the temperature of the entering mixed gas T in in real time. The PID controller compares the measured temperature with the set value T set , calculates the temperature deviation e=T set -T inPID operation is performed to generate a control output signal u (an analog quantity, 0-10V or 4-20mA) sent to an electric control proportional valve. The electric control proportional valve adjusts the valve opening degree according to the PID output to change the methanol flow rate (the air flow rate is constant) into the catalytic combustor, so as to change the combustion temperature and the output gas temperature of the catalytic combustor.

[0029] The heating gas output by the catalytic combustor enters the methanol engine, and the temperature sensor measures the temperature again and feeds back to the PID controller to complete the closed-loop regulation. The control logic can be divided into the following key steps and variables: PID control algorithm: the controller calculates the proportional term, integral term and differential term according to the deviation e: u(t)=K P e(t)+K I ∫e(t) dt+K D de(t) / dt Variable definition: set temperature T set (60-70℃), actual measured temperature T in , temperature deviation e=T set -T in , PID output control quantity u (0-10V or 4-20mA analog signal), etc.

[0030] Wherein K P , K I , K D are the proportional, integral and differential coefficients respectively.

[0031] The formula shows that the PID control is based on the proportional, cumulative and change trend of the deviation between the set value and the measured value for regulation. When T in <T set , the deviation is positive, the PID increases the output signal u, so that the three-way valve opening degree is increased, the methanol supply amount of the catalytic combustor is increased, and the output temperature is increased; on the contrary, when T in >T set , the deviation is negative, the PID reduces the valve opening degree, and the output temperature is reduced.

[0032] Feedback Closed-Loop Structure: The system employs negative feedback closed-loop control. A temperature sensor continuously sends the intake air temperature at the methanol engine inlet to the PID controller, which compares it with the setpoint and outputs a control signal to drive the actuator. The actuator—an electronically controlled proportional valve—receives the PID output (0-10VDC or 420mA) and adjusts the valve opening; 0V corresponds to a slightly closed valve, and 10V corresponds to a fully open valve. Changes in valve opening cause changes in the methanol flow rate into the catalytic combustor, thereby regulating the combustion gas temperature and outputting heated gas to the methanol engine. The methanol engine inlet temperature is fed back to the PID controller by the sensor, forming a closed loop that allows the system to automatically adjust to near the setpoint based on deviations.

[0033] Cold start of a methanol engine includes the following steps: S1. Before a cold start of the engine, air and methanol are mixed through a gas mixer. The mixer uses a Venturi-induced structure to draw in atomized methanol droplets using negative pressure and creates turbulence through multi-stage baffles, making the air and methanol mix more evenly. This structure ensures precise control of the methanol injection quantity, and the λ value (air-fuel ratio) can be dynamically adjusted between 0.8 and 1.4 to ensure optimal combustion performance.

[0034] S2. The temperature sensor monitors the temperature of the air-fuel mixture in real time. The temperature control module determines whether the pre-combustion unit needs to be activated. When the temperature of the air-fuel mixture is ≥60℃, the air-fuel mixture is sent into the methanol engine and the methanol engine starts normally. When the temperature of the gas mixture does not reach the ignition threshold (i.e., <60℃), adjust the conduction state of the electronically controlled three-way valve to send part of the gas mixture into the pulse plasma catalytic burner for pre-combustion.

[0035] S3. After the gas mixture enters the pulse plasma catalytic burner, it is first activated in the plasma zone of the catalytic burner: ① Pulsed high-voltage discharge: The electrodes (anode titanium alloy coated with platinum, cathode tungsten) generate pulsed plasma at a voltage of 10–20kV and a frequency of 30–50 kHz, releasing high-energy electrons and active particles (such as O and OH free radicals). ② These active particles break the chemical bonds between methanol molecules (CH3OH) and oxygen molecules (O2), reducing the activation energy of the reaction. This allows oxidation reactions that are difficult to occur at low temperatures (such as methanol decomposition and oxidation) to be initiated at temperatures below -20°C, solving the problem that traditional catalysts cannot be ignited at low temperatures.

[0036] After being excited by plasma, the mixed gas enters a catalytic zone filled with a gradient composite catalyst, where the complete oxidation of methanol is achieved through layered catalysis. ①Inlet section (Pt / CeO2): Platinum (Pt) is the active component, which can catalyze the initial oxidation of methanol at 20–30℃ to produce formaldehyde (HCHO) and intermediate products; CeO2 is a co-catalyst, which promotes oxygen transfer and reduces formaldehyde accumulation through its oxygen storage and release capacity.

[0037] ②Mid-stage (Pd / ZrO2): Palladium (Pd) further catalyzes the deep oxidation of intermediate products, converting formaldehyde and other substances into carbon dioxide (CO2) and water (H2O); ZrO2 serves as a support, improving the thermal stability and anti-sintering ability of the catalyst.

[0038] ③Outlet blank layer: Through heat exchange in the catalyst-free area, the outlet gas temperature is controlled to be stable at 60–70℃ to avoid the impact of overheating on subsequent pipelines.

[0039] The chemical equation for the entire catalytic reaction can be simplified to: 2CH3OH + 3O2 → 2CO2 + 4H2O + heat The heat released by the reaction raises the gas temperature to 60–70°C, meeting the requirement for heating the mixed gas.

[0040] When the temperature is below the set value (e.g., <60℃), the PID controller automatically increases the methanol supply and adjusts the valve opening to increase the burner's output temperature. When the temperature is too high (e.g., >70℃), the PID system reduces the valve opening, decreases the methanol supply, and keeps the temperature stable within the set range.

[0041] S4. When the temperature of the heated gas reaches 60~70℃, the heated gas is returned to the gas mixer by the return pump. By heating the mixed gas, the methanol achieves a good vaporization effect and is ignited by the engine spark plug, ensuring that the temperature inside the engine cylinder rises rapidly to the auto-ignition temperature of methanol (about 470℃), providing the necessary heat for engine starting.

[0042] S5. After the methanol engine starts successfully, the pre-combustion circuit is automatically shut off, the pulse plasma catalytic burner is disconnected, and the normal operating mode is restored. Through the precise adjustment of methanol supply and air flow by the temperature control system, efficient combustion and emission compliance are ensured throughout the entire process from cold start to full-load operation.

[0043] The above description is merely a preferred embodiment of this utility model. The protection scope of this utility model is not limited to the above embodiments. All technical solutions falling within the scope of this utility model's concept are protected. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of this utility model should also be considered within the protection scope of this utility model.

Claims

1. A cold start system for a methanol engine based on pulsed plasma catalytic combustion, characterized in that: Includes a gas mixer, a methanol engine, a pulsed plasma catalytic combustor, and a reflux pump; The gas mixer has a venturi structure inside, with air entering the inlet section, methanol entering the throat section, and an electronically controlled proportional valve at the outlet. The outlet of the gas mixer is connected to the methanol engine and the pulse plasma catalytic combustor via an electronically controlled three-way valve. The pulsed plasma catalytic burner has a plasma zone and a catalytic zone inside; electrode plates are provided on both sides of the plasma zone, and the catalytic zone is filled with catalyst; the inlet of the pulsed plasma catalytic burner is connected to the outlet of the gas mixer, the outlet is connected to a reflux pump, and the reflux pump is connected to the throat section of the gas mixer through a reflux pipe.

2. The methanol engine cold start system based on pulsed plasma catalytic combustion as described in claim 1, characterized in that: It also includes a temperature control module, which includes a temperature sensor and a PID controller. The temperature sensor is located at the mixing outlet of the gas mixer and is used to monitor the temperature of the mixed gas. The PID controller is used to control the on / off state of the electronically controlled three-way valve and to adjust the opening degree of the electronically controlled proportional valve.

3. The methanol engine cold start system based on pulsed plasma catalytic combustion as described in claim 1, characterized in that: The gas mixer includes an inlet section, a contraction section, a throat section, a diffusion section, and a mixing section. The inlet section is connected to air. The throat section is connected to two paths, one to methanol and the other to the mixed gas heated by a pulsed plasma catalytic burner. The mixing section is equipped with multi-stage turbulence-inducing blades.

4. The methanol engine cold start system based on pulsed plasma catalytic combustion as described in claim 1, characterized in that: The electronically controlled proportional valve is used to adjust the ratio λ of air to methanol, and the ratio λ is 0.8~1.

4.

5. The methanol engine cold start system based on pulsed plasma catalytic combustion as described in claim 1, characterized in that: The plasma zone of the pulsed plasma catalytic burner is located near the inlet, and the catalytic zone is located near the outlet; the anode of the plasma zone is made of titanium alloy with a platinum coating, and the cathode is made of tungsten.

6. The methanol engine cold start system based on pulsed plasma catalytic combustion as described in claim 1, characterized in that: The catalytic zone is provided with multiple corrugated channels, and the corrugated channels are provided with several perforations; foam ceramics are filled between adjacent corrugated channels, and the foam ceramics are connected to the corrugated channels through the perforations.

7. The methanol engine cold start system based on pulsed plasma catalytic combustion as described in claim 1, characterized in that: The corrugated channel is divided into three sections. The surface of the first section is coated with Pt / CeO2, the surface of the second section is coated with Pd / ZrO2, and the surface of the third section is blank.

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