An emergency ammonia leakage treatment method and device for a vehicle-mounted ammonia power system

Abstract

The application discloses an emergency ammonia leakage treatment method and device for a vehicle-mounted ammonia power system, and the method comprises the following steps: collecting pipeline pressure, nozzle end pressure, ammonia tank end and engine end ammonia gas concentration and pipeline key joint vibration data at a high frequency; the GCU calculates a pressure drop rate, and determines a rupture early warning when the pressure drop rate exceeds a first rate threshold; reading an ammonia gas sensor concentration value to confirm the rupture; performing a graded protection action according to the leakage grade, performing emergency shutdown and triggering root cutoff when the pipeline is ruptured, switching to a pure diesel mode when there is moderate leakage, and combining a geographic fence to judge a stop area, triggering an alarm and performing human-machine cooperative leakage point positioning when there is trace leakage; the leaked ammonia gas is collected by a double-layer metal hose outer pipe and is sent into a dilution tank for closed-loop absorption treatment. The application realizes the whole-process prevention and control from millisecond-level rupture prediction to graded treatment, leakage point positioning and harmless treatment, and takes into account the timeliness of detection and the accuracy of treatment.

Description

Technical Field

[0001] This invention relates to the field of vehicle-mounted intelligent safety monitoring and control technology, specifically to an emergency ammonia leakage handling method and device for a vehicle-mounted ammonia power system. Background Technology

[0002] Ammonia is being gradually applied to vehicle power systems as a clean fuel. However, there is a risk of leakage during the storage, transportation, and injection of liquid ammonia or ammonia gas. Ammonia gas is corrosive and toxic, and leaks can easily cause safety accidents and environmental pollution. Therefore, leakage protection of vehicle ammonia power systems is a key issue for their commercial application.

[0003] Existing solutions for handling leaks in vehicle-mounted ammonia-powered systems have the following main shortcomings:

[0004] (1) The existing solution relies on an ammonia concentration sensor to detect leaks. It can only trigger the protection action after the ammonia has diffused to the sensor location and the concentration has reached the alarm threshold. The response is obviously delayed and cannot achieve a rapid response at the moment of pipeline rupture. It is prone to false alarms due to pressure fluctuations. At the same time, it lacks early detection of the causes of leakage. The vehicle environment is continuously subjected to vibration loads, and the pipeline joints are prone to loosening under long-term alternating stress, which is one of the main causes of ammonia leakage. The existing solution cannot provide early warning intervention in the stage of loosening but before leakage.

[0005] (2) In terms of leak location and maintenance guidance, the existing solution can only determine whether the leak occurred on the ammonia tank side or the engine side, and cannot further narrow down the scope of investigation. After receiving the alarm, maintenance personnel still need to blindly inspect each joint along the pipeline, resulting in low investigation efficiency.

[0006] (3) Most existing pipelines adopt a single-layer conveying structure. After leakage, ammonia gas directly diffuses into the vehicle or the external environment. There is no leakage collection and recovery treatment process, which can easily cause environmental and personal injury. Although some schemes use double-walled pipes to collect leaked ammonia gas, the subsequent treatment method is passive absorption. There is a lack of closed-loop monitoring of the treatment process. After the absorption medium is saturated, there is a risk of secondary ammonia gas escape.

[0007] (4) The existing solution’s leakage handling strategy is a single-vehicle closed decision-making, which lacks linkage with the vehicle’s external environment information and cannot dynamically adjust the handling strategy according to the type of space in which the vehicle is located, resulting in ammonia accumulation and secondary safety risks. Summary of the Invention

[0008] (a) Technical problems to be solved

[0009] To address the shortcomings of existing technologies, this invention provides an emergency ammonia leak handling method and apparatus for vehicle-mounted ammonia power systems, solving the problems mentioned in the background section.

[0010] (II) Technical Solution

[0011] To achieve the above objectives, the present invention provides an emergency ammonia leak handling method for a vehicle-mounted ammonia power system, comprising the following steps: S1: Real-time pressure values ​​in the ammonia supply pipeline are acquired via a high-frequency pressure transmitter, real-time pressure values ​​at the nozzle end are acquired via an NGPT sensor, and real-time vibration data at key pipeline joints are acquired via a vibration sensor. S2: The vehicle control unit (GCU) calculates the pressure drop rate within a preset time window. When the pressure drop rate exceeds the first preset rate threshold, it is determined to be a rupture warning and proceeds to S3. When the pressure drop rate does not exceed the first preset rate threshold, monitoring continues according to the conventional concentration grading detection logic. S3: In the rupture warning state, the GCU reads the real-time concentration values ​​of the ammonia sensor at the ammonia tank end and the ammonia sensor at the engine end; if the concentration exceeds the rupture confirmation threshold, it is determined that the pipeline rupture is confirmed, and S4 is executed; if the concentration does not exceed the rupture confirmation threshold, the rupture warning is lifted and normal monitoring is restored. S4: Execute graded protection actions based on the leakage assessment results: When a pipeline rupture is confirmed, the entire vehicle is shut down immediately, and the low-temperature overflow shut-off valve at the root of the ammonia tank is triggered to shut off at the root. When the ammonia concentration is in the medium leakage threshold range, the liquid ammonia solenoid valve and the gaseous ammonia solenoid valve are shut off, and the power system is switched to pure diesel mode. When the ammonia concentration is in the trace leakage threshold range, a leakage inspection alarm is triggered and the current power mode is maintained. S5: Leaked ammonia gas is collected through the outer tube of a double-layered metal hose and sent to a dilution tank for absorption and treatment. After treatment, the gas is filtered twice and then discharged into the air.

[0012] Furthermore, step S1 also includes a joint loosening warning step: The GCU establishes a vibration spectrum baseline model for each critical joint in the pipeline under normal operating conditions. When the real-time vibration spectrum at a certain joint location is abnormal relative to the vibration spectrum baseline model, it is determined as a joint loosening warning, triggering a preventive tightening prompt. When the ammonia sensor corresponding to the same joint location detects a minor leak after the joint loosening warning, the GCU associates the joint loosening warning with the minor leak event, marks it as a leak caused by vibration loosening, and prompts the maintenance guide to tighten the joint at that location.

[0013] Furthermore, in S2, the pressure drop rate The calculation method is as follows: ; In the formula, The pipeline pressure value collected by the pressure transmitter at the start point of the preset time window; The pipeline pressure value collected by the pressure transmitter at the end of the preset time window. The preset time window is the time interval from the start point to the end point.

[0014] Furthermore, after determining a moderate leak and switching to pure diesel mode in step S4, the following steps are also included: S41a: The GCU obtains the vehicle's current location via GPS and combines it with map data to determine whether the vehicle is in a no-parking zone such as a tunnel, bridge, or underground garage. S42a: If in a no-stopping zone, maintain the pure diesel limited power operation state, plan the shortest driving route, and simultaneously switch the dilution tank vent valve to internal circulation mode to prohibit the emission of gas outside the vehicle until leaving the no-stopping zone. Then, restore the vent valve to the state of being connected to the atmosphere to discharge the absorbed gas and perform a safe stop. If not in a no-stopping zone, directly perform a safe pull-over.

[0015] Furthermore, step S42a also includes a diluent treatment step: When the ambient temperature exceeds the preset high temperature threshold, the circulation disturbance frequency of the absorbent in the dilution tank is automatically increased to improve the uniformity and dynamic diffusion rate of the dilution in the dilution tank and compensate for the decrease in ammonia solubility at high temperature. When the altitude exceeds the preset altitude threshold, the residence time of the treated gas in the activated carbon filter section is automatically extended to compensate for the accelerated gas escape under low pressure.

[0016] Furthermore, after determining a minor leak in S4 and triggering a leak inspection alarm, a human-machine collaborative leak point location step is also included: S41b: Based on the order and ratio of the concentration increases detected by the ammonia sensor at the ammonia tank end and the ammonia sensor at the engine end, the GCU initially determines that the leak point is near the ammonia tank end or the engine end. S42b: The instrument panel displays segmented troubleshooting guidance information, guiding operators to use portable ammonia test strips to perform non-contact ammonia escape confirmation at each node in the preset pipeline node sequence. S43b: The operator feeds back the confirmation results of each node to the GCU. The GCU combines the sensor data with the manual confirmation results to calculate the distance of the leak point relative to the ammonia sensor at the ammonia tank end. The specific pipeline section where the leak is located can be identified using the following formula: ; In the formula, This refers to the total length of the pipeline from the ammonia sensor at the ammonia tank end to the ammonia sensor at the engine end. The time when the ammonia sensor at the ammonia tank end detects the peak value of the concentration gradient. The time when the ammonia sensor at the engine end detects the peak value of the concentration gradient. This represents the diffusion rate of ammonia gas within the pipeline. S44b: The GCU reports the positioning results to the OBD system.

[0017] Furthermore, the above-mentioned emergency ammonia leak handling method also includes sensor self-diagnosis and fault tolerance steps: the GCU establishes an ammonia concentration prediction model based on pressure and temperature correlation parameters; when the deviation between the measured value of the ammonia sensor and the predicted value of the model continues to exceed a preset threshold, the sensor is determined to be faulty, the ammonia concentration input source of the safety control logic is switched to the virtual concentration signal generated by the prediction model, the safety monitoring function is maintained without degradation, and a sensor fault alarm is triggered.

[0018] Furthermore, the above-mentioned emergency ammonia leak handling method also includes a pipeline health assessment step: the GCU continuously records the frequency, duration and cumulative concentration of micro-leakage events, and triggers a preventive maintenance prompt when the cumulative leakage amount and leakage frequency exceed the preset health threshold.

[0019] Furthermore, S5 also includes a closed-loop management process for the absorption medium in the dilution tank: real-time acquisition of pH value and liquid level data of the absorption liquid in the dilution tank; automatic triggering of absorption liquid replacement and water replenishment operations when the pH value exceeds the preset saturation threshold; and closing the leaking ammonia gas inlet valve when the liquid level exceeds the preset safety threshold.

[0020] Furthermore, an emergency ammonia leak handling device for a vehicle-mounted ammonia power system, applied to the above-mentioned leak handling method, includes: The ammonia tank body has a low-temperature overflow shut-off valve integrated at its base. The double-layer metal hose has an inner tube for ammonia delivery and an outer tube for collecting leaked ammonia. A dilution tank, connected to the outer pipe, is used to absorb and treat the collected leaked ammonia gas; The ammonia gas sensor at the ammonia tank end and the ammonia gas sensor at the engine end are used to detect the ammonia gas concentration at both ends, respectively. Pressure transmitters and NGPT sensors are used to collect pressure at the ammonia tank end and nozzle end, respectively. Vibration sensors are placed at key pipe joints to collect vibration data; The vehicle control unit (GCU) is electrically connected to various sensors, liquid ammonia solenoid valves, gaseous ammonia solenoid valves, and cryogenic overcurrent shut-off valves.

[0021] (III) Beneficial Effects

[0022] (1) This invention improves the detection response of pipeline rupture from the second-level response of traditional concentration alarms, which require waiting for ammonia to diffuse to the sensor, to the millisecond-level response through the dual mechanism of pressure drop rate prediction and ammonia concentration confirmation. At the same time, the secondary confirmation of the concentration sensor effectively avoids false alarms caused by instantaneous pressure fluctuations. By monitoring the vibration spectrum changes of key pipeline joints through vibration sensors, an early warning is issued when the joint is loose but has not yet leaked. The vibration abnormality event is causally correlated with the subsequent minor leakage event, and various fault types such as pipeline rupture, moderate leakage, minor leakage, and ammonia blockage are distinguished and corresponding graded protection actions are triggered, avoiding unnecessary shutdowns or fault expansion, and taking into account detection speed, judgment accuracy and fault diagnosis depth.

[0023] (2) This invention uses the difference in the timing of the peak concentration gradient of the dual sensors to perform electronic coarse positioning, initially determining that the leak point is close to the ammonia tank end or the engine end, thus narrowing down the scope of investigation. On this basis, the instrument panel displays structured segmented investigation guidance information, guiding the operator to use portable ammonia test strips to perform non-contact confirmation segment by segment according to the preset pipeline node sequence. Finally, the distance to the leak point is accurately calculated by combining the sensor data and the manual confirmation results using the positioning formula. The combination of electronic detection and manual confirmation significantly shortens the fault investigation time and reduces the labor intensity of blind inspection by maintenance personnel. At the same time, the positioning results are uploaded through the OBD system, allowing the maintenance station to obtain the leak location information in advance and prepare the corresponding spare parts.

[0024] (3) The present invention adopts an integrated structure of inner tube transportation and outer tube collection of double-layer metal hose to realize the fully enclosed collection of leaked ammonia from the leak point to the dilution tank, and prevents ammonia from spreading to the vehicle or the external environment. Through real-time closed-loop monitoring of pH sensor and liquid level sensor in dilution tank, when the pH value of the absorbent exceeds the saturation threshold, the absorbent replacement and water replenishment operation is automatically triggered. When the liquid level exceeds the safety threshold, the leaked ammonia inlet valve is automatically closed to prevent secondary ammonia escape and dilution tank overflow caused by saturation of absorbent medium. At the same time, GCU records the amount of ammonia absorbed in each leak event, calculates the remaining effective capacity of absorbent medium, and issues a preventive replacement reminder before the medium fails, realizing the full-process automated closed-loop management and predictive maintenance of the treatment process.

[0025] (4) After switching to pure diesel mode in the case of moderate leakage, the GCU combines GPS and map data to determine the no-parking area, distinguish between enclosed scenarios such as tunnels, bridges, and underground garages and open roads, and plan the shortest driving route to avoid ammonia accumulation and secondary safety risks caused by parking in enclosed spaces.

[0026] (5) In this invention, when the ammonia sensor fails, the GCU generates a virtual concentration signal based on the ammonia concentration prediction model established by the related parameters such as pressure and temperature, and automatically switches to the input source of the safety control logic. Algorithm redundancy replaces hardware redundancy. Without increasing the cost of additional sensor hardware or occupying additional vehicle installation space, the safety monitoring function is maintained without degradation, thus solving the safety protection problem during the vacuum period from sensor failure to repair. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall process of the present invention; Figure 2 This is a schematic diagram of the workflow of step S2 in this invention; Figure 3 This is a schematic diagram of the workflow of step S4 in this invention; Figure 4 This is a schematic diagram of the overall structure of the vehicle-mounted emergency ammonia leak treatment device of the present invention; Figure 5 This is another schematic diagram of the overall structure of the vehicle-mounted emergency ammonia leak treatment device of the present invention; Figure 6 This is a schematic diagram of the internal structure of the double-layer metal hose in this invention.

[0028] In the picture: 1-Ammonia tank body; 2-Cryogenic overflow shut-off valve; 3-Double-layer metal hose; 31-Inner pipe; 32-Outer pipe; 4-Dilution tank; 5-Ammonia sensor at the ammonia tank end; 6-Ammonia sensor at the engine end; 7-Pressure transmitter; 8-NGPT sensor; 9-Vibration sensor; 10-GCU; 11-Liquid ammonia solenoid valve; 12-Gasmic ammonia solenoid valve. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Please see Figures 1 to 6 As shown, the embodiments of the present invention provide the following technical solutions:

[0031] Example 1

[0032] This embodiment provides an emergency ammonia leak handling method for a vehicle-mounted ammonia power system, including the following steps. Please refer to [link / reference]. Figure 1 : S1: The real-time pressure value in the ammonia supply pipeline is collected by the pressure transmitter 7 at high frequency, the real-time pressure value at the nozzle end is collected by the NGPT sensor 8, and the real-time vibration data at the key joints of the pipeline is collected by the vibration sensor 9. Step S1 also includes a joint loosening warning step: The GCU10 establishes a vibration spectrum baseline model for each critical pipeline joint under normal operating conditions. This vibration spectrum baseline model is established by performing a Fast Fourier Transform on vibration signals collected at each joint location under normal operating conditions to extract the amplitude and energy distribution characteristics of each frequency band. When the real-time vibration spectrum at a certain joint location is abnormal relative to the vibration spectrum baseline model, it is determined as a joint loosening warning, triggering a preventive tightening prompt. The abnormality determination conditions are: the amplitude of a certain frequency band exceeds a preset multiple of the amplitude of the corresponding frequency band in the baseline model, or the total energy of the vibration signal exceeds a preset multiple of the total energy of the baseline model, and the duration exceeds a preset determination period. When the ammonia sensor corresponding to the same joint location detects a minor leak after the joint loosening warning, the GCU10 associates the joint loosening warning with the minor leak event, marks it as a leak caused by vibration loosening, and prompts the maintenance guide to tighten the joint at that location. The key pipeline joints include the connection joints between the ammonia tank outlet and the liquid ammonia solenoid valve 11, between the liquid ammonia solenoid valve 11 and the pre-vaporizer, between the pre-vaporizer and the post-vaporizer, between the post-vaporizer and the pressure regulating valve, between the pressure regulating valve and the ammonia filter, and between the ammonia filter and the nozzle assembly.

[0033] S2: The vehicle control unit GCU10 calculates the pressure drop rate within a preset time window. When the pressure drop rate exceeds a first preset rate threshold, a rupture warning is issued, and the process proceeds to S3. When the pressure drop rate does not exceed the first preset rate threshold, monitoring continues according to a preset concentration threshold grading logic. Please refer to [link to relevant documentation]. Figure 2 ; In S2, the pressure drop rate The calculation method is as follows: ; In the formula, The pipeline pressure value collected by pressure transmitter 7 is the starting point of the preset time window; The pipeline pressure value collected by pressure transmitter 7 at the end of the preset time window. The preset time window length, i.e., the time interval from the start point to the end point. Time window length The recommended value is 0.1s to 0.5s. This value needs to balance response speed and anti-interference capability. If the value is too small, it is easily affected by instantaneous pressure fluctuations, leading to false alarms. Excessive values ​​will increase response delay; the first preset rate threshold is determined based on the system's rated operating pressure and pipeline rupture test data. When the value is negative and its absolute value exceeds the first preset rate threshold, it indicates that the pipeline pressure has dropped sharply in a short period of time, which is judged as a rupture warning.

[0034] The preset concentration threshold grading logic includes: when the ammonia concentration is below the first concentration threshold, it is determined that there is no leakage and the system continues to operate normally; when the ammonia concentration is between the first concentration threshold and the second concentration threshold, it is determined that there is a minor leak, triggering a leak inspection alarm and maintaining the current power mode; when the ammonia concentration is between the second concentration threshold and the third concentration threshold, it is determined that there is a moderate leak, shutting off the liquid ammonia solenoid valve 11 and the gaseous ammonia solenoid valve 12, and switching the power system to pure diesel mode.

[0035] S3: In the rupture warning state, GCU10 reads the real-time concentration values ​​of ammonia sensor 5 at the ammonia tank end and ammonia sensor 6 at the engine end; if the concentration exceeds the rupture confirmation threshold, it is determined that the pipeline rupture is confirmed, and S4 is executed; if the concentration does not exceed the rupture confirmation threshold, the rupture warning is lifted and the system continues to operate in a leak-free state; the rupture confirmation threshold is higher than the third concentration threshold, and its specific value is determined based on the relationship between ammonia diffusion rate and concentration in the pipeline rupture test.

[0036] S4: Execute graded protection actions based on the leakage determination results. Please refer to [link / reference]. Figure 3 : When a pipeline rupture is confirmed, the entire vehicle is shut down immediately, and the cryogenic overflow shut-off valve 2 at the root of the ammonia tank body 1 is triggered to perform root shut-off. The cryogenic overflow shut-off valve 2 adopts a purely mechanical structure. When the ammonia flow rate through the valve body exceeds the preset large flow rate threshold, the valve core automatically closes under the action of fluid pressure difference, without the need for electrical control signal triggering, thereby cutting off the liquid ammonia supply from the source. When the ammonia concentration is in the moderate leakage threshold range, shut off the liquid ammonia solenoid valve 11 and the gaseous ammonia solenoid valve 12, and switch the power system to pure diesel mode. When the ammonia concentration is within the trace leakage threshold range, a leakage inspection alarm is triggered and the current power mode is maintained.

[0037] After determining a moderate leak and switching to pure diesel mode in step S4, the following steps are also included: S41a: The GCU10 obtains the vehicle's current location via GPS and combines it with map data to determine whether the vehicle is in a no-parking zone such as a tunnel, bridge, or underground parking garage. The type of no-parking zone can be pre-stored in the GCU10's storage unit or obtained in real time via the vehicle network. S42a: If in a no-stopping zone, maintain the pure diesel limited-power operation, plan the shortest departure route, and simultaneously switch the vent valve of dilution tank 4 to internal circulation mode, prohibiting the emission of gas outside the vehicle until leaving the no-stopping zone. Then, restore the vent valve to the state of being open to the atmosphere to release the absorbed gas (the gas here refers to the clean gas remaining after the ammonia has been fully absorbed by the diluent, mainly air and a small amount of nitrogen), and perform a safe stop. If not in a no-stopping zone, directly perform a safe pull-over. Step S42a also includes a diluent treatment step: When the ambient temperature exceeds the preset high temperature threshold, the circulation disturbance frequency of the absorbent in the dilution tank 4 is automatically increased to improve the uniformity and dynamic diffusion rate of the dilution in the dilution tank 4, and to compensate for the decrease in ammonia solubility at high temperature. The increase in circulation disturbance frequency is positively correlated with the temperature difference exceeding the high temperature threshold. When the altitude exceeds the preset altitude threshold, the residence time of the treated gas in the activated carbon filter section is automatically extended to compensate for the accelerated gas escape under low pressure. The extension of residence time is positively correlated with the altitude difference exceeding the altitude threshold.

[0038] After determining a minor leak in S4 and triggering a leak inspection alarm, the process also includes a human-machine collaborative leak location step: S41b: Based on the order and ratio of the concentration increase detected by the ammonia sensor 5 at the ammonia tank end and the ammonia sensor 6 at the engine end, GCU10 initially determines whether the leak point is near the ammonia tank end or the engine end; when the ammonia sensor 5 at the ammonia tank end detects the concentration increase before the ammonia sensor 6 at the engine end, and the concentration ratio is greater than the preset ratio threshold, the leak point is determined to be near the ammonia tank end; otherwise, the leak point is determined to be near the engine end. S42b: The instrument panel displays segmented troubleshooting guidance information, instructing operators to use portable ammonia test strips to sequentially confirm ammonia escape at each node according to the preset pipeline node sequence. The pipeline node sequence is as follows: ammonia tank outlet connector, liquid ammonia solenoid valve 11 inlet and outlet connectors, pre-vaporizer inlet and outlet connectors, post-vaporizer inlet and outlet connectors, pressure regulator inlet and outlet connectors, ammonia filter inlet and outlet connectors, and nozzle assembly inlet connector. Before conducting the troubleshooting, operators must ensure that the engine is off, the hood and ammonia tank door are open and naturally ventilated for at least 1 minute. Operators should stand upwind during the troubleshooting, and the recommended troubleshooting time for each node should not exceed 30 seconds. The portable ammonia test strip changes from yellow to dark brown upon contact with ammonia, with a color change response speed of less than 1 second and a detection sensitivity of up to 1 ppm. S43b: The operator feeds back the confirmation results of each node to GCU10 through the instrument panel interface or vehicle diagnostic interface. GCU10 combines the sensor data with the manual confirmation results to calculate the distance of the leak point relative to the ammonia sensor 5 at the ammonia tank end. The specific pipeline section where the leak is located can be identified using the following formula: ; In the formula, This refers to the total length of the pipeline from ammonia sensor 5 at the ammonia tank end to ammonia sensor 6 at the engine end. The time when the ammonia sensor 5 at the ammonia tank end detects the peak value of the concentration gradient. The time when the ammonia sensor 6 at the engine end detects the peak value of the concentration gradient. The diffusion rate of ammonia gas within the pipeline; when At that time, the leak point was closer to the engine end; when At that time, the leak point was closer to the ammonia tank end; the diffusion rate The value of is affected by factors such as the pressure and temperature of the medium in the pipeline, the pipe diameter, and the leakage hole diameter, and needs to be determined in advance through system calibration tests; the concentration gradient peak value refers to the moment when the concentration rise rate reaches its maximum value in the curve of ammonia concentration change over time detected by the sensor. S44b: GCU10 reports the location results to the OBD system, allowing the maintenance station to obtain the leak location information in advance and prepare the corresponding spare parts through the OBD system.

[0039] S5: Leaked ammonia gas is collected through the outer pipe 32 of the double-layer metal hose 3 and sent to the dilution tank 4 for absorption treatment. After treatment, the gas is filtered twice and then discharged into the air.

[0040] S5 also includes a closed-loop management process for the absorption medium in dilution tank 4: real-time acquisition of pH value and liquid level data of the absorption liquid in dilution tank 4; automatic triggering of absorption liquid replacement and water replenishment operations when the pH value exceeds the preset saturation threshold; and closing the leaking ammonia inlet valve to prevent dilution tank 4 from overflowing when the liquid level exceeds the preset safety threshold.

[0041] The specific implementation method of the closed-loop management steps for the absorption medium in the dilution tank 4 is as follows: As ammonia is continuously absorbed, the initial pH value of the fresh absorbent increases, the concentration of ammonia monohydrate in the absorbent increases, and the pH value rises accordingly. When the pH value exceeds the preset saturation threshold, it indicates that the absorbent is close to ammonia saturation. The GCU10 automatically opens the drain valve at the bottom of the dilution tank 4 to discharge the saturated ammonia water into the vehicle wastewater storage tank, and opens the water replenishment valve at the top of the dilution tank 4 to replenish fresh water until the pH value returns to the initial set range.

[0042] The remaining effective capacity of the above-mentioned absorption medium Calculate as follows: ; In the formula, The initial total ammonia absorption capacity specified by the manufacturer for the absorption medium; For the first The ammonia absorption capacity consumed in a single leak event; the amount consumed in a single leak event. The calculation method is as follows:

[0043] In the formula, The ammonia absorption coefficient corresponding to a unit pH change was determined through experimental calibration. The pH value of the absorbent before the leak occurred; This refers to the pH value of the absorbent solution after the handling of the leak incident. This refers to the volume of the absorbent in dilution tank 4. When When the temperature drops below the preset threshold, the GCU10 triggers a preventative maintenance prompt, reminding operators to replace the absorbent medium in a timely manner.

[0044] In addition, the above-mentioned emergency ammonia leakage handling method for vehicle-mounted ammonia power systems also includes sensor self-diagnosis and fault tolerance steps: GCU10 establishes an ammonia concentration prediction model based on pressure and temperature correlation parameters; when the deviation between the measured value of the ammonia sensor and the predicted value of the model continues to exceed a preset threshold, the sensor is determined to be faulty, the ammonia concentration input source of the safety control logic is switched to the virtual concentration signal generated by the prediction model, the safety monitoring function is maintained without degradation, and a sensor fault alarm is triggered.

[0045] The ammonia concentration prediction model described above can be a multiple linear regression model, the expression of which is: ; In the formula, This is a model estimate of the ammonia concentration; This represents the real-time pressure value of the pipeline. This refers to the real-time temperature value of the pipeline. This represents the real-time flow rate of ammonia. These are the weighting coefficients for each correlation parameter. The weighting coefficients and bias terms are constants for the bias term; these are obtained through training using the least squares regression method based on historical normal operating data collected during the system calibration phase. When the measured value of the ammonia sensor... With model estimates deviation If the deviation exceeds the preset threshold continuously and the duration exceeds the preset judgment time, the GCU10 determines that the ammonia sensor is faulty.

[0046] Furthermore, the emergency ammonia leak handling method for the vehicle-mounted ammonia power system also includes a pipeline health assessment step: the GCU10 continuously records the frequency, duration, and cumulative concentration of minor leak events. When the cumulative leakage amount and leakage frequency exceed the preset health threshold, a preventive maintenance prompt is triggered.

[0047] The cumulative leakage The calculation method is as follows: ; In the formula, This represents the cumulative leakage amount from a single minor leakage event. For the first Ammonia concentration values ​​at each sampling point; The time interval between adjacent sampling points is denoted as . The GCU10 sums the product of concentration and time at all sampling points within the duration of each minor leak event to obtain the cumulative leak amount for that event. When the average cumulative leak amount of the most recent N minor leak events exceeds the first health threshold, or the frequency of minor leak events exceeds the second health threshold, the GCU10 determines that the pipeline health has declined and triggers a preventive maintenance prompt.

[0048] Example 2

[0049] An emergency ammonia leak handling device for a vehicle-mounted ammonia power system, applied to the aforementioned leak handling method, see details below. Figure 4 , Figure 5 and Figure 6 ,include: The ammonia tank body 1 has a cryogenic overflow shut-off valve 2 integrated at its base and fixedly connected thereto; the cryogenic overflow shut-off valve 2 is used to automatically trigger mechanical action when a large flow leakage occurs, so as to achieve the shut-off of liquid ammonia delivery at the base of the ammonia tank body 1.

[0050] The double-layer metal hose 3 adopts an integrated double-layer pipe structure. Its inner pipe 31 is an ammonia gas delivery channel, used to sequentially deliver liquid ammonia or ammonia gas to the vaporization, filtration, and injection components. The outer pipe 32 is a leak ammonia gas collection channel, used to collect all leaked ammonia gas caused by pipeline malfunctions and send it to the leak detection and recovery pipe. The double-layer metal hose 3 is fixedly connected to each pipeline section between the ammonia tank body 1 and the pre-vaporizer, the pre-vaporizer and the post-vaporizer, the post-vaporizer and the pressure regulating valve, the pressure regulating valve and the ammonia filter, and the ammonia filter and the nozzle assembly.

[0051] The dilution tank 4 is connected and fixedly connected to the outer pipe 32 through a leak detection and recovery pipe, and is used to absorb and treat the collected leaked ammonia gas. The internal volume of the dilution tank 4 is 50L, and the tank is filled with ammonia water absorption medium. The dilution tank 4 is equipped with a pH sensor and a liquid level sensor for real-time monitoring of the absorption liquid status.

[0052] Ammonia sensor 5 at the ammonia tank end and ammonia sensor 6 at the engine end are used to simultaneously detect leaks of ammonia in the recovery pipe and minor leaks in ammonia tank assembly components and joints. Ammonia sensor 5 at the ammonia tank end is integrated into the ammonia tank assembly and fixedly connected to it. It is used to detect minor leaks in engine end components and joints. Pressure transmitter 7 and NGPT sensor 8 are used to collect pressure at the ammonia tank end and pressure at the nozzle end, respectively; Vibration sensors 9 are arranged at key pipeline joints and are fixedly connected to them for collecting vibration data; the key pipeline joints include the connection joints between the ammonia tank outlet and the liquid ammonia solenoid valve 11, between the liquid ammonia solenoid valve 11 and the pre-vaporizer, between the pre-vaporizer and the post-vaporizer, between the post-vaporizer and the pressure regulating valve, between the pressure regulating valve and the ammonia filter, and between the ammonia filter and the nozzle assembly.

[0053] The vehicle control unit GCU10 is electrically connected to the pressure transmitter 7, NGPT sensor 8, ammonia sensor 5 at the ammonia tank end, ammonia sensor 6 at the engine end, vibration sensor 9, liquid ammonia solenoid valve 11, gaseous ammonia solenoid valve 12, and cryogenic overcurrent shut-off valve 2. Signals from all sensing components are transmitted to GCU10, which processes the data and triggers emergency protection actions. GCU10 is also linked to the vehicle's OBD system. The device also includes a pre-vaporizer, a post-vaporizer, a pressure regulator, an ammonia filter, a nozzle assembly, and an engine mixer. All components are sequentially fixed together via double-layer metal hoses 3.

[0054] Example 3

[0055] This embodiment applies to a heavy-duty truck's onboard ammonia-diesel dual-fuel power system with a rated operating pressure of 0.8 MPa. In this embodiment, the ammonia concentration grading thresholds are set as follows: first concentration threshold 5 ppm (lower limit for trace leakage), second concentration threshold 50 ppm (lower limit for moderate leakage), third concentration threshold 200 ppm (upper limit for moderate leakage), and rupture confirmation threshold 500 ppm; the first preset rate threshold for pressure drop is determined based on pipeline rupture test calibration; the dilution tank 4 has an internal volume of 50 L and is filled with ammonia water absorption medium; the ammonia sensor 5 at the ammonia tank end is integrated into the ammonia tank assembly, and the ammonia sensor 6 at the engine end is installed at the engine-side nozzle connector; vibration sensors 9 are arranged at key pipeline connectors. The pressure transmitter 7, NGPT sensor 8, ammonia sensor, and vibration sensor 9 are connected to the GCU10 via a CAN bus, and the GCU10 is linked to the vehicle's OBD system.

[0056] The working process of this embodiment is as follows: During normal system operation, liquid ammonia enters the pre-vaporizer and post-vaporizer from the ammonia tank body 1 via the liquid ammonia solenoid valve 11 for vaporization. The vaporized ammonia gas is then regulated by a pressure regulator, filtered by an ammonia filter, and enters the nozzle assembly via the gaseous ammonia solenoid valve 12. The nozzle assembly then injects a metered amount of ammonia into the engine mixer for combustion. During this process, the GCU10 continuously receives and analyzes data from various sensors.

[0057] When vibration sensor 9 detects an anomaly in the vibration spectrum at a critical pipe joint location relative to the baseline model, GCU10 determines it as a loose joint warning and triggers a preventative tightening prompt in the cab. If subsequently, the ammonia sensor at the same joint location detects a trace leak (concentration between 5 ppm and 50 ppm), GCU10 associates the loosening warning with the leak event, marks it as a leak caused by vibration loosening, and prompts the maintenance guide to tighten the joint at that location.

[0058] When the rate of decrease in pipeline pressure detected by pressure transmitter 7 exceeds the first preset rate threshold within a preset time window, GCU10 determines it as a rupture warning. If the concentration value detected by ammonia sensor 6 at the ammonia tank end or engine end exceeds 500ppm at this time, GCU10 determines it as a confirmed pipeline rupture, immediately controls the vehicle to shut down urgently, and the cryogenic overflow shut-off valve 2 is triggered simultaneously to cut off the liquid ammonia delivery at the root of ammonia tank body 1. The leaked ammonia is collected by the outer pipe 32 of the double-layer metal hose 3 and sent to the dilution tank 4 for absorption and treatment.

[0059] When the ammonia sensor detects a concentration between 50ppm and 200ppm (moderate leakage), the GCU10 automatically shuts off the liquid ammonia solenoid valve 11 and the gaseous ammonia solenoid valve 12, switching the power system to pure diesel mode. At this time, the GCU10 obtains the vehicle's current location via GPS. If the vehicle is in a no-stopping area such as a tunnel, bridge, or underground parking garage, it maintains limited power operation in pure diesel mode, plans the shortest exit route, and simultaneously switches the vent valve of the dilution tank 4 to internal recirculation mode, prohibiting the emission of gas outside the vehicle. If the ambient temperature exceeds 35℃, it automatically increases the frequency of the absorbent circulation disturbance in the dilution tank 4. If the altitude exceeds 2000m, it automatically extends the residence time of the activated carbon filter section. After leaving the no-stopping area, the normal venting function of the dilution tank 4 is restored, and a safe stop is executed.

[0060] When the ammonia sensor detects a concentration between 5 ppm and 50 ppm (minor leak), the GCU10 triggers an audible and visual alarm for leak inspection in the cab. The system maintains ammonia-powered mode. Based on the order in which the concentration increases from the ammonia tank-side sensor and the engine-side sensor, the GCU10 initially determines which end the leak is closer to. The instrument panel displays a segmented troubleshooting guide, instructing operators to perform non-contact ammonia escape confirmation using portable ammonia test strips, following the sequence of ammonia tank outlet connector, liquid ammonia solenoid valve 11 inlet and outlet connectors, pre-vaporizer inlet and outlet connectors, post-vaporizer inlet and outlet connectors, pressure regulator inlet and outlet connectors, ammonia filter inlet and outlet connectors, and nozzle assembly inlet connector. Combining sensor data and manual confirmation results, the GCU10 calculates the distance to the leak point using a positioning formula, pinpoints the specific pipeline section where the leak is located, and reports the location results to the OBD system.

[0061] When the pressure transmitter 7 detects a pressure of 0.8 MPa, the NGPT sensor 8 detects a pressure close to 0, and there are no abnormalities in the ammonia gas sensors 6 at both the ammonia tank end and the engine end, the GCU10 determines that the ammonia circuit is blocked, triggers a blockage alarm, and switches the power system to pure diesel mode.

[0062] When the ammonia sensor malfunctions, the GCU10 generates a virtual concentration signal based on a predictive model established by the correlation parameters of pressure and temperature. This signal is then switched to the input source of the safety control logic to maintain the safety monitoring function without degradation, while simultaneously triggering a sensor fault alarm.

[0063] Example 4

[0064] This embodiment is applicable to the on-board ammonia power system of a small passenger vehicle. To meet the requirements of lightweighting, the difference from Embodiment 3 is that: the dilution tank 4 is replaced with a micro adsorption dilution device with a volume of 10L, filled with a mixture of activated carbon and ammonia water adsorption medium; the ammonia concentration classification threshold is set as follows: the first concentration threshold is 3ppm, the second concentration threshold is 30ppm, the third concentration threshold is 150ppm, and the rupture confirmation threshold is 300ppm; the double-layer metal hose 3 is made of lightweight aluminum alloy, and the remaining processing methods and device structure are the same as in Embodiment 3.

[0065] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0066] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0067] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for handling emergency ammonia leaks in a vehicle-mounted ammonia power system, characterized in that, Includes the following steps: S1: Real-time pressure values ​​in the ammonia supply pipeline are acquired via a high-frequency pressure transmitter, real-time pressure values ​​at the nozzle end are acquired via an NGPT sensor, and real-time vibration data at key pipeline joints are acquired via a vibration sensor. Step S1 also includes a joint loosening warning step: The GCU establishes a vibration spectrum baseline model for each critical joint in the pipeline under normal operating conditions. When the real-time vibration spectrum at a certain joint location is abnormal relative to the vibration spectrum baseline model, it is determined as a joint loosening warning, triggering a preventive tightening prompt. When the ammonia sensor corresponding to the same joint location detects a minor leak after the joint loosening warning, the GCU associates the joint loosening warning with the minor leak event, marks it as a leak caused by vibration loosening, and prompts the maintenance guide to tighten the joint. S2: The vehicle control unit (GCU) calculates the pressure drop rate within a preset time window. When the pressure drop rate exceeds a first preset rate threshold, it is determined to be a rupture warning and proceeds to S3. When the pressure drop rate does not exceed the first preset rate threshold, monitoring continues according to the preset concentration threshold grading logic. S3: In the rupture warning state, the GCU reads the real-time concentration values ​​of the ammonia sensor at the ammonia tank end and the ammonia sensor at the engine end; if the concentration exceeds the rupture confirmation threshold, it is determined that the pipeline rupture is confirmed, and S4 is executed; if the concentration does not exceed the rupture confirmation threshold, the rupture warning is lifted and the system continues to operate in the no-leakage state. S4: Execute graded protection actions based on the leakage assessment results: When a pipeline rupture is confirmed, the entire vehicle is shut down immediately, and the low-temperature overflow shut-off valve at the root of the ammonia tank is triggered to shut off at the root. When the ammonia concentration is in the medium leakage threshold range, the liquid ammonia solenoid valve and the gaseous ammonia solenoid valve are shut off, and the power system is switched to pure diesel mode. When the ammonia concentration is in the trace leakage threshold range, a leakage inspection alarm is triggered and the current power mode is maintained. After determining a minor leak in S4 and triggering a leak inspection alarm, the process also includes a human-machine collaborative leak point location step: S41b: Based on the order and ratio of the concentration increases detected by the ammonia sensor at the ammonia tank end and the ammonia sensor at the engine end, the GCU initially determines that the leak point is near the ammonia tank end or the engine end. S42b: The instrument panel displays segmented troubleshooting guidance information, guiding operators to use portable ammonia test strips to perform non-contact ammonia escape confirmation at each node in the preset pipeline node sequence. S43b: The operator feeds back the confirmation results of each node to the GCU. The GCU combines the sensor data with the manual confirmation results to calculate the distance of the leak point relative to the ammonia sensor at the ammonia tank end. The specific pipeline section where the leak is located can be identified using the following formula: ； In the formula, This refers to the total length of the pipeline from the ammonia sensor at the ammonia tank end to the ammonia sensor at the engine end. The time when the ammonia sensor at the ammonia tank end detects the peak value of the concentration gradient. The time when the ammonia sensor at the engine end detects the peak value of the concentration gradient. This represents the diffusion rate of ammonia gas within the pipeline. S44b: The GCU reports the positioning results to the OBD system; S5: Leaked ammonia gas is collected through the outer tube of a double-layered metal hose and sent to a dilution tank for absorption treatment.

2. The emergency ammonia leak handling method for a vehicle-mounted ammonia power system according to claim 1, characterized in that, In S2, the pressure drop rate The calculation method is as follows: ； In the formula, The pipeline pressure value collected by the pressure transmitter at the start point of the preset time window; The pipeline pressure value collected by the pressure transmitter at the end of the preset time window. The preset time window is the time interval from the start point to the end point.

3. The emergency ammonia leakage handling method for a vehicle-mounted ammonia power system according to claim 1, characterized in that, After determining a moderate leak and switching to pure diesel mode in step S4, the following steps are also included: S41a: The GCU obtains the vehicle's current location via GPS and combines it with map data to determine whether the vehicle is in a no-parking zone such as a tunnel, bridge, or underground garage. S42a: If in a no-stopping zone, maintain the pure diesel limited power operation state, plan the shortest driving route, and simultaneously switch the dilution tank vent valve to internal circulation mode to prohibit the emission of gas outside the vehicle until leaving the no-stopping zone. Then, restore the vent valve to the state of being connected to the atmosphere to discharge the absorbed gas and perform a safe stop. If not in a no-stopping zone, directly perform a safe pull-over.

4. The emergency ammonia leakage handling method for a vehicle-mounted ammonia power system according to claim 3, characterized in that, Step S42a further includes a diluent treatment step: When the ambient temperature exceeds the preset high temperature threshold, the circulation disturbance frequency of the absorbent in the dilution tank is automatically increased to improve the uniformity and dynamic diffusion rate of the dilution in the dilution tank and compensate for the decrease in ammonia solubility at high temperatures.

5. The emergency ammonia leak handling method for a vehicle-mounted ammonia power system according to claim 1, characterized in that, It also includes sensor self-diagnosis and fault tolerance steps: the GCU establishes an ammonia concentration prediction model based on pressure and temperature correlation parameters; when the deviation between the measured value of the ammonia sensor and the model prediction value continues to exceed a preset threshold, the sensor is determined to be faulty, the ammonia concentration input source of the safety control logic is switched to the virtual concentration signal generated by the prediction model, the safety monitoring function is maintained without degradation, and a sensor fault alarm is triggered.

6. The emergency ammonia leak handling method for a vehicle-mounted ammonia power system according to claim 1, characterized in that, It also includes a pipeline health assessment step: the GCU continuously records the frequency, duration and cumulative concentration of minor leak events. When the cumulative leakage amount and frequency exceed the preset health threshold, a preventive maintenance prompt is triggered.

7. The emergency ammonia leakage handling method for a vehicle-mounted ammonia power system according to claim 1, characterized in that, S5 also includes a closed-loop management process for the absorption medium in the dilution tank: real-time acquisition of pH value and liquid level data of the absorption liquid in the dilution tank; automatic triggering of absorption liquid replacement and water replenishment operations when the pH value exceeds the preset saturation threshold; and closing the leaking ammonia gas inlet valve when the liquid level exceeds the preset safety threshold.

8. An emergency ammonia leak handling device for a vehicle-mounted ammonia power system, applied to the leak handling method described in claim 1, characterized in that, include: The ammonia tank body has a low-temperature overflow shut-off valve integrated at its base. The double-layer metal hose has an inner tube for ammonia delivery and an outer tube for collecting leaked ammonia. A dilution tank, connected to the outer pipe, is used to absorb and treat the collected leaked ammonia gas; The ammonia gas sensor at the ammonia tank end and the ammonia gas sensor at the engine end are used to detect the ammonia gas concentration at both ends, respectively. Pressure transmitters and NGPT sensors are used to collect pressure at the ammonia tank end and nozzle end, respectively. Vibration sensors are placed at key pipe joints to collect vibration data; The vehicle control unit (GCU) is electrically connected to various sensors, liquid ammonia solenoid valves, gaseous ammonia solenoid valves, and cryogenic overcurrent shut-off valves.

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