High-efficiency hydrogen internal combustion engine post-processing system and method

Abstract

The invention discloses an efficient hydrogen internal combustion engine post-treatment method, relates to the field of hydrogen internal combustion engine post-treatment, and solves the technical problems that an existing hydrogen internal combustion engine post-treatment system is high in complexity and poor in low-temperature performance, and the treatment effect is affected by water vapor interference. The method comprises the steps that part of water vapor in exhaust gas of the hydrogen internal combustion engine is converted into condensate water, the inlet NOx concentration is obtained, the inlet NOx concentration is compared with a preset NOx target emission limit value, and when the inlet NOx concentration is larger than the NOx target emission limit value, the needed NH3 synthesis amount is calculated according to the inlet NOx concentration and the preset NOx target emission limit value; and according to the required NH3 synthesis amount, the injection rate and the plasma power are calculated, the flow of condensate water is controlled according to the injection rate, and the plasma power serves as the output power of the PSCR reactor. The invention further discloses a high-efficiency hydrogen internal combustion engine aftertreatment system. The method does not depend on urea, and the installation cost of a urea-related treatment device is reduced.

Description

Technical Field

[0001] This invention relates to the field of hydrogen internal combustion engine aftertreatment, and more specifically, to a high-efficiency hydrogen internal combustion engine aftertreatment system and method. Background Technology

[0002] Hydrogen engines are considered a significant alternative to traditional fossil fuel engines due to their zero-carbon emissions. However, during the high-temperature combustion process, nitrogen and oxygen in the air still react to produce NO. X It has become a major pollutant. Furthermore, due to the low ignition energy and rapid diffusion of hydrogen, incomplete combustion is prone to occur, resulting in small amounts of unburned H2 in the exhaust gas. Currently, measures are being taken to address NO... X The mainstream technology for control is selective catalytic reduction (SCR), which relies on injecting an aqueous urea solution (AdBlue) into the exhaust pipe. The urea solution pyrolyzes to produce NH3, which then reacts with NO on the catalyst surface. X The reaction produces N2 and H2O. However, this technology has the following significant drawbacks:

[0003] The system is highly complex: it requires a urea storage tank, metering pump, injection valve, heating and defrosting device and control system, which increases the overall vehicle cost, weight and potential failure points; Poor low-temperature performance: Urea crystallizes below -11°C, requiring additional energy for thawing; traditional SCR catalysts typically have an ignition temperature above 200°C, resulting in high NO levels during the cold start phase. x The conversion efficiency is extremely low; Water vapor interference: The exhaust of hydrogen engines contains more than 60% water. In traditional SCR, a large amount of water vapor will inhibit NH3 adsorption, reduce catalyst activity, and even cause condensation corrosion. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a high-efficiency hydrogen internal combustion engine aftertreatment system and method to address the shortcomings of the existing technology, thereby solving the technical problems of high complexity, poor low-temperature performance and water vapor interference affecting the treatment effect of the existing hydrogen internal combustion engine aftertreatment system.

[0005] The present invention discloses an efficient aftertreatment method for a hydrogen internal combustion engine. The method involves converting a portion of the water vapor in the exhaust gas of the hydrogen internal combustion engine into condensate, obtaining the inlet NOx concentration, comparing the inlet NOx concentration with a preset NOx target emission limit, and calculating the required NH3 synthesis amount based on the inlet NOx concentration and the preset NOx target emission limit when the inlet NOx concentration exceeds the limit. The method also involves calculating the injection rate and plasma power based on the required NH3 synthesis amount, controlling the flow rate of condensate injected into the PSCR reactor based on the injection rate, and using the plasma power as the output power of the PSCR reactor.

[0006] With further improvement, the expression for calculating the required amount of NH3 synthesized is as follows: ; in, n_NH3 The required amount of NH3 to be synthesized. k Stoichiometric coefficient C_target NOx target emission limits, C_in This represents the NOx concentration at the inlet.

[0007] Furthermore, the expression for calculating the injection rate is as follows: ; in, Q_water For the injection rate, n_NH 3 represents the required amount of NH3 to be synthesized, and k1 is the first proportionality coefficient.

[0008] Furthermore, the expression for calculating the plasma power is as follows: ; in, p For plasma power, n_NH3 K is the required amount of NH3 to be synthesized, and k2 is the second proportionality coefficient.

[0009] Furthermore, when the inlet NOx concentration is less than or equal to the NOx target emission limit, it enters a low-power standby mode.

[0010] Furthermore, after the PSCR reactor starts working, an NH3 concentration threshold is set, and the outlet NOx concentration and NH3 concentration of the PSCR reactor are obtained. The conversion efficiency is obtained based on the inlet NOx concentration and outlet NOx concentration, and the ammonia slip degree is obtained based on the NH3 concentration and NH3 concentration threshold. The injection rate and plasma power are adjusted based on the ammonia slip degree and conversion efficiency.

[0011] A high-efficiency hydrogen internal combustion engine aftertreatment system, the system comprising, The condensation unit is used to convert some of the water vapor in the exhaust of the hydrogen internal combustion engine into condensate. PSCR reactor, used for exhaust gas post-treatment; An inlet NOx sensor is used to acquire the inlet NOx concentration of the PSCR reactor and output the inlet NOx concentration signal; A water pump, installed downstream of the condensation unit, is used to spray the condensate into the PSCR reactor; The ECU receives the inlet NOx concentration signal and uses the aforementioned efficient hydrogen internal combustion engine aftertreatment method to control the water pump and PSCR reactor based on the inlet NOx concentration.

[0012] Beneficial effects The advantages of this invention are: This invention obtains the inlet NOx concentration and compares it with a preset NOx emission limit. When the inlet NOx concentration exceeds the target emission limit, the required NH3 synthesis amount is calculated based on the inlet NOx concentration and the preset target emission limit. The injection rate and plasma power are then calculated based on the required NH3 synthesis amount. The flow rate of condensate is controlled based on the injection rate, and the plasma power is used as the output power of the PSCR reactor. This achieves urea independence, reduces the installation cost of urea-related treatment devices, and improves space utilization. It also enables low-temperature start-up, avoiding the poor low-temperature treatment performance caused by urea treatment. Furthermore, it utilizes water vapor in the exhaust gas for condensation and incorporation into the SCR treatment, avoiding water vapor interference and improving resource utilization. Attached Figure Description

[0013] Figure 1 This is a flowchart of the high-efficiency hydrogen internal combustion engine aftertreatment method of the present invention; Figure 2 This is a simplified structural diagram of the high-efficiency hydrogen internal combustion engine aftertreatment system of the present invention.

[0014] The components are: 1-hydrogen engine exhaust system, 2-condensation unit, 3-micro water storage chamber, 4-inlet NOx sensor, 5-outlet NOx sensor, 6-ECU, and 7-PSCR reactor. Detailed Implementation

[0015] 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.

[0016] See Figures 1-2 The present invention provides an efficient after-treatment method for hydrogen internal combustion engines, such as... Figure 1 As shown, this method involves converting some of the water vapor in the exhaust of a hydrogen internal combustion engine into condensate, and then using the condensate in the exhaust to add it to the SCR treatment. This avoids interference from water vapor and improves resource utilization.

[0017] Obtain the inlet NOx concentration and compare it with the preset NOx target emission limit. If the inlet NOx concentration is greater than the NOx target emission limit, calculate the required NH3 synthesis amount based on the inlet NOx concentration and the preset NOx target emission limit.

[0018] The formula for calculating the required amount of NH3 to be synthesized is as follows: ; in, n_NH3 The required amount of NH3 to be synthesized. k Stoichiometric coefficient C_target NOx target emission limits, C_in This represents the NOx concentration at the inlet.

[0019] Calculate the jet rate and plasma power based on the required NH3 synthesis amount. The feed ratio of H2O:N2 is approximately 3:1. Based on the target NH3 synthesis amount, the injection rate of the micro-pump is proportional to the required NH3 synthesis amount. Therefore, the following relationship can be obtained: .

[0020] The above relationship can be transformed into an expression for calculating the injection rate as follows: ; in, Q_water For the injection rate, n_NH 3 represents the required amount of NH3 synthesized, k1 is the first proportionality coefficient, and k1 is the correlation coefficient between the injection rate and the amount of NH3 synthesized.

[0021] Similarly, the plasma power output p is proportional to the required n_NH3, thus yielding the following relationship: .

[0022] The above relationship can be transformed into the following expression for calculating plasma power: ; in, p For plasma power, n_NH3 The required amount of NH3 to be synthesized. k2 This is the second proportionality coefficient.

[0023] The flow rate of condensate injected into PSCR reactor 7 is controlled according to the injection rate, and the plasma power is used as the output power of PSCR reactor 7. Under the synergistic effect of plasma and catalyst, NH3 is efficiently synthesized by in-situ reduction reaction of N2 and H2O in the exhaust gas in the upstream region of the reactor.

[0024] This allows for independence from urea, reducing the installation costs of urea-related treatment equipment and improving space utilization; it also enables low-temperature start-up, avoiding the situation where urea treatment leads to poor low-temperature treatment performance.

[0025] The synthesized NH3 is carried to the downstream catalytic zone of the PSCR along with the exhaust gas. NH3 reacts with NOx in the catalytic zone to generate N2 and H2O (standard SCR pathway). At the same time, the active species generated in the plasma field can also promote the direct reduction of NOx and the oxidative removal of unburned hydrogen (non-SCR pathway).

[0026] After purification, the gas is released into the atmosphere. Throughout the process, the ECU monitors the inlet NO... X Concentration sensor and outlet NO X Feedback signals from concentration sensors or other relevant sensors are used to dynamically adjust plasma power and water spray rate in a closed loop, continuously optimizing system performance.

[0027] When the inlet NOx concentration is less than or equal to the NOx target emission limit, it enters a low-power standby mode.

[0028] Once the PSCR reactor starts operating, an NH3 concentration threshold is set, and the outlet NOx and NH3 concentrations of the PSCR reactor are obtained. The conversion efficiency is then calculated based on the inlet and outlet NOx concentrations. This calculation method is existing technology and will not be elaborated upon in this invention. The ammonia slip is then determined based on the NH3 concentration and the NH3 concentration threshold. The injection rate and plasma power are adjusted based on the ammonia slip and the conversion efficiency.

[0029] By comparing the NH3 concentration with the NH3 concentration threshold, if the NH3 concentration is less than the NH3 concentration threshold, the degree of ammonia escape is determined to be mild; if the NH3 concentration is greater than or equal to the NH3 concentration threshold, the degree of ammonia escape is determined to be severe.

[0030] Set a conversion efficiency threshold and compare the conversion efficiency threshold with the conversion efficiency. If the conversion efficiency is less than the conversion efficiency threshold and the ammonia slip is severe, it is determined that the injection rate and plasma power need to be adjusted; otherwise, no adjustment is needed.

[0031] The method for adjusting the injection rate and plasma power is as follows: First, obtain the initial injection rate and initial plasma power. Then, subtract the NH3 concentration from an NH3 concentration threshold to obtain the NH3 concentration difference. Next, subtract the conversion efficiency from a conversion efficiency threshold to obtain the conversion efficiency difference. Based on the NH3 concentration difference and conversion efficiency difference, calibrate the injection rate correction value and plasma power correction value. Finally, add the injection rate correction value to the initial injection rate to obtain the target injection rate, and add the plasma power correction value to the initial plasma power to obtain the target plasma power. This achieves closed-loop dynamic adjustment of the plasma power and water injection rate, continuously optimizing system performance and preventing ammonia escape and plasma anomalies caused by excessive NH3 synthesis.

[0032] like Figure 2 As shown, a high-efficiency hydrogen internal combustion engine aftertreatment system includes, The condensation unit 2 is located at the end of the exhaust manifold or in a bypass branch of the hydrogen internal combustion engine. It includes a compact thermoelectric cooler (TEC) or a high-efficiency plate / fin heat exchanger. Downstream of the cooler is a miniature water storage chamber 3 (volume ≤50 mL) equipped with a hydrophobic membrane and a water pump. Utilizing exhaust waste heat (which can be optimized through heat exchange design) or an external power source to drive the TEC, the high-temperature humid exhaust gas with high water content is cooled to below its dew point (e.g., <80°C), causing a portion of the water vapor (H2O) to condense into liquid water. This trace amount of liquid water is filtered through the hydrophobic membrane and temporarily stored in the miniature water storage chamber 3, serving as the hydrogen source required for subsequent NH3 synthesis.

[0033] PSCR reactor 7 is used for exhaust gas aftertreatment. The reactor shell houses a dielectric barrier discharge (DBD) or gliding arc plasma generation module. The core of the reactor is its internal catalytic unit.

[0034] The electrode surface or dielectric layer of PSCR reactor 7 is coated with a bifunctional composite catalyst coating, distributed in zones or gradients: Upstream catalytic zone: supported with a highly efficient NH3 synthesis catalyst (such as Ru / Al2O3, Fe-K / Al2O3, or Co-Mo-N). X Downstream catalytic zone: Supported with SCR catalysts exhibiting excellent low-temperature activity (such as Cu-SSZ-13 and Fe-ZSM-5 zeolite molecular sieves). The catalyst coating can be arranged in a physical partition layout or in a functional gradient on the electrode / dielectric layer surface.

[0035] The working process of PSCR reactor 7: In-situ NH3 synthesis: A micro water pump, according to control commands, precisely atomizes stored liquid water into the required amount and sprays it into the inlet of the PSCR reactor; a high-voltage power supply excites the plasma module to generate high-energy electrons (electrons). - Excited-state molecules and highly reactive free radicals (·H, ·OH, ·N); under the synergistic effect of plasma field strength and upstream catalyst, injected H2O and N2 in exhaust gas are decomposed and activated (dissociated) in the plasma field, and NH3 is synthesized on the surface of upstream catalyst via a Haber-Bosch-like pathway; NOx synergistic reduction: Pathway 1 (SCR-like reaction): NH3 generated in situ enters the downstream catalytic zone with the gas flow, and reacts with NO x Standard SCR reaction occurs Pathway 2 (Direct Plasma Reduction): The plasma-generated H₂, activated H₂, and electrons directly reduce NOx (e.g., ...). Unburned hydrogen (H2slip) removal: Unburned H2 in the exhaust gas is oxidized to H2O by reactive oxygen atoms (·O) and hydroxyl radicals (·OH) generated in the environment in the plasma, or participates in the NOx reduction reaction, achieving dual purification.

[0036] The inlet NOx sensor 4 is used to obtain the inlet NOx concentration of the PSCR reactor 7 and output the inlet NOx concentration signal.

[0037] A water pump, installed downstream of condensation unit 2, is used to spray condensate into PSCR reactor 7.

[0038] ECU6 receives the inlet NOx concentration signal and uses the aforementioned efficient hydrogen internal combustion engine aftertreatment method to control the water pump and PSCR reactor 7 based on the inlet NOx concentration.

[0039] The system also includes an outlet NOx sensor 6 located at the PSCR reactor 7.

[0040] The air inlet of the condensing unit 2 is connected to the exhaust port of the hydrogen engine exhaust system. The condensate outlet of the condensing unit 2 is connected to the water inlet of the micro water storage chamber 3. The water outlet of the micro water storage chamber 3 is connected to the water inlet of the PSCR reactor 7 through a pipe. A water pump is installed on the pipe connecting the micro water storage chamber 3 and the PSCR reactor 7. The inlet NOx sensor 4 is installed at the air inlet of the PSCR reactor 7, and the outlet NOx sensor 6 is installed at the air outlet of the PSCR reactor 7. Both the inlet NOx sensor 4 and the outlet NOx sensor 6 are electrically connected to the ECU 6 (controller).

[0041] 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 high-efficiency hydrogen internal combustion engine aftertreatment method, characterized in that, The method involves converting some water vapor in the exhaust of a hydrogen internal combustion engine into condensate, obtaining the inlet NOx concentration, comparing the inlet NOx concentration with a preset NOx target emission limit, and calculating the required NH3 synthesis amount based on the inlet NOx concentration and the preset NOx target emission limit when the inlet NOx concentration is greater than the NOx target emission limit. The injection rate and plasma power are calculated based on the required NH3 synthesis amount, and the flow rate of condensate injected into the PSCR reactor (7) is controlled based on the injection rate. The plasma power is used as the output power of the PSCR reactor (7).

2. The high-efficiency hydrogen internal combustion engine aftertreatment method according to claim 1, characterized in that, The formula for calculating the required amount of NH3 to be synthesized is as follows: ； in, n_NH3 This represents the required amount of NH3 synthesized. k Stoichiometric coefficient C_target NOx target emission limits, C_in This represents the NOx concentration at the inlet.

3. The high-efficiency hydrogen internal combustion engine aftertreatment method according to claim 1, characterized in that, The formula for calculating the injection rate is as follows: ； in, Q_water For the injection rate, n_NH 3 represents the required amount of NH3 to be synthesized, and k1 is the first proportionality coefficient.

4. The high-efficiency hydrogen internal combustion engine aftertreatment method according to claim 1, characterized in that, The expression for calculating the plasma power is as follows: ； in, p For plasma power, n_NH3 K is the required amount of NH3 to be synthesized, and k2 is the second proportionality coefficient.

5. The high-efficiency hydrogen internal combustion engine aftertreatment method according to claim 1, characterized in that, When the inlet NOx concentration is less than or equal to the NOx target emission limit, it enters a low-power standby mode.

6. The high-efficiency hydrogen internal combustion engine aftertreatment method according to claim 1, characterized in that, Once the PSCR reactor starts operating, an NH3 concentration threshold is set, and the outlet NOx concentration and NH3 concentration of the PSCR reactor are obtained. The conversion efficiency is obtained based on the inlet NOx concentration and outlet NOx concentration, and the ammonia slip is obtained based on the NH3 concentration and the NH3 concentration threshold. The injection rate and plasma power are adjusted based on the ammonia slip and the conversion efficiency.

7. A high-efficiency hydrogen internal combustion engine aftertreatment system, characterized in that, The system includes, The condensation unit (2) is used to convert some of the water vapor in the exhaust gas of the hydrogen internal combustion engine into condensate. PSCR reactor (7) is used for exhaust gas post-treatment; An inlet NOx sensor (4) is used to obtain the inlet NOx concentration of the PSCR reactor (7) and output the inlet NOx concentration signal; A water pump, installed downstream of the condensation unit (2), is used to spray the condensate into the PSCR reactor (7); ECU (6) receives the inlet NOx concentration signal and uses the efficient hydrogen internal combustion engine aftertreatment method according to any one of claims 1-6 to control the water pump and PSCR reactor (7) based on the inlet NOx concentration.

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