Liquid ammonia ejector anti-icing heating device utilizing tail gas waste heat and method of liquid ammonia ejector anti-icing heating device

Abstract

The invention discloses a liquid ammonia ejector anti-icing heating device utilizing tail gas waste heat and a method thereof. The liquid ammonia ejector anti-icing heating device comprises a control module, a tail gas heat guiding module, a heating sleeve and a heat exchange medium cooling module. The heating sleeve sleeves and is in heat conduction contact with the outer wall of a liquid ammonia ejector of the ammonia-hydrogen engine; an engine exhaust manifold adjusts the flow of tail gas introduced into the tail gas heat guiding module through a waste gas bypass valve. A first heat exchange channel in the tail gas heat guiding module, a second heat exchange channel in the heating sleeve and a third heat exchange channel of the heat exchange medium cooling module are connected in series through a first branch and a second branch to form a medium circulation loop. The control module dynamically adjusts the opening degree of the waste gas bypass valve and the second electromagnetic valve and the rotating speed of the driving pump according to the temperature of the nozzle of the liquid ammonia ejector, so that the flow and the speed of a heat exchange medium in the medium circulation loop are adjusted, and the temperature of the nozzle of the liquid ammonia ejector is kept at 40-80 DEG C through tail gas waste heat in the operation process of an engine.

Description

Technical Field

[0001] This invention relates to the field of internal combustion engine technology, and is a liquid ammonia injector anti-icing heating device and method that utilizes waste heat from exhaust gas. Background Technology

[0002] In recent years, zero-carbon fuels have become an important direction for the development of internal combustion engine technology. Liquid ammonia (NH3), as a highly promising hydrocarbon-free carrier, has attracted widespread attention due to its convenience in production, storage, and transportation. However, directly injecting liquid ammonia into the engine cylinder for combustion faces a key technical challenge: liquid ammonia has an extremely high latent heat of vaporization at room temperature (approximately 1370 kJ / kg). During direct injection in the engine combustion chamber, liquid ammonia rapidly absorbs heat and evaporates, causing a sharp drop in the temperature of the injector nozzle and surrounding metal components. When the injection duration is long or the ambient temperature is low, severe icing can occur at the injector tip due to condensation and frosting of moisture in the air. This icing leads to poor fuel atomization, reduced injection flow, and even injector needle valve sticking and failure, seriously affecting the stable operation and combustion efficiency of the engine.

[0003] Currently, there is no effective solution to the problem of injector icing in ammonia fuel engines. The conventional approach is to introduce electric heating elements, such as wrapping heating wires around the injector or integrating a PTC (positive temperature coefficient) heater. However, this method has significant drawbacks: firstly, electric heating consumes a lot of power, increasing the energy burden on the entire vehicle and hindering energy efficiency; secondly, introducing high-voltage electric heating introduces complex electrical control, insulation safety, and electromagnetic compatibility design issues, increasing system complexity and cost, and making compact integration difficult in space-constrained engines.

[0004] In the field of waste heat utilization, existing technologies offer some inspiration. For example, CN103291426B discloses a waste heat recovery and utilization device for automotive exhaust gas. This device recovers waste heat from exhaust gas through a collector, stores the heat in a heat accumulator, and finally uses a heat exchanger to heat engine components such as coolant and oil, thereby improving low-temperature starting performance. This technology demonstrates the feasibility of using exhaust gas waste heat to heat engine components; however, its system is complex, focuses on serving the engine itself, and does not offer a solution for the fuel injector, a specific component requiring rapid and precise thermal management.

[0005] Therefore, there is an urgent need in this field for a dedicated solution to the icing problem of liquid ammonia direct injection injectors. An ideal device should be able to utilize readily available heat sources inherent in engine operation without relying on an external power source, and should be characterized by its compact structure, rapid response, simple control, and continuous operation to ensure the stable and reliable operation of ammonia fuel engines under various operating conditions. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention proposes a liquid ammonia injector anti-icing heating device and method utilizing exhaust gas waste heat. The liquid ammonia injector anti-icing heating device utilizing exhaust gas waste heat is integrated into the ammonia-hydrogen engine body. It utilizes exhaust gas waste heat recovery + high-efficiency heat pipe heating jacket structure + closed-loop control strategy to achieve internal energy recycling with zero additional energy consumption.

[0007] The first aspect of this invention is to provide a liquid ammonia injector anti-icing heating device utilizing exhaust gas waste heat. The heating device is integrated into the ammonia-hydrogen engine body and includes a control module, an exhaust gas heat extraction module, a heating jacket, and a heat exchange medium cooling module. The heating jacket is fitted and heat-conductingly contacts the outer wall of the liquid ammonia injector of the engine body, and has a second heat exchange channel inside. Its main body is arranged around the nozzle area of ​​the liquid ammonia injector. The control module is communicatively connected to the engine's ECU. The exhaust manifold of the engine regulates the exhaust gas flow rate into the exhaust gas heat extraction module through an exhaust gas bypass valve. The exhaust gas heating module is integrated into the exhaust manifold of the engine body, and a first heat exchange channel is provided inside it. The exhaust gas from the engine flows through the exhaust gas heating module to heat up the heat exchange medium in the first heat exchange channel. The heat exchange medium cooling module is integrated into the engine body and located between the exhaust gas heating module and the heating jacket. A third heat exchange channel is provided inside it, and cooling water is used to cool down the heat exchange medium in the third heat exchange channel. The first heat exchange channel of the exhaust gas heating module, the second heat exchange channel of the heating jacket, and the third heat exchange channel of the heat exchange medium cooling module are connected in series through the first branch and the second branch to form a medium circulation loop. The inlet of the third heat exchange channel is connected to the second branch through the first solenoid valve, and its outlet is connected to the second branch through the third solenoid valve; a drive pump is installed on the first branch. On the second branch, a second solenoid valve is also provided between the first solenoid valve and the third solenoid valve; the first solenoid valve, the second solenoid valve and the third solenoid valve are all electrically connected to the control module. The control module dynamically adjusts the opening degree of the exhaust bypass valve, the second solenoid valve, and the speed of the drive pump according to the temperature at the nozzle of the liquid ammonia injector, thereby adjusting the flow rate and speed of the heat exchange medium in the medium circulation loop, so that the engine can use the waste heat of the exhaust gas to maintain the temperature at the nozzle of the liquid ammonia injector at 40-80 ℃ during operation.

[0008] Furthermore, a temperature sensor is provided on the inner wall of the heating jacket. The temperature sensor is located at the nozzle of the liquid ammonia injector and is used to measure and feed back the temperature of the nozzle area to the control module in real time. The temperature sensor is electrically connected to the control module.

[0009] Furthermore, a temperature control unit is also provided on the first branch, the temperature control unit including a PID control unit and a pressure sensor and a flow sensor provided on the first branch; the drive pump, pressure sensor and flow sensor are all electrically connected to the PID control unit; the PID control unit receives the control signal from the control module and performs closed-loop regulation of the speed of the drive pump.

[0010] Furthermore, the first and third heat exchange channels are S-shaped pipe discs respectively installed in the exhaust gas heat extraction module and the heat exchange medium cooling module, and the S-shaped pipes are selected from stainless steel thin-walled pipes or S-shaped metal pipes; the second heat exchange channel is an annular metal pipe.

[0011] Optionally, the material of the S-shaped metal tube is selected from one of the following: copper, copper alloy, aluminum, and aluminum alloy.

[0012] Furthermore, the inner wall surface of the second heat exchange channel is provided with a capillary wick structure.

[0013] Furthermore, the capillary core structure is a sintered metal powder layer or a metal wire mesh.

[0014] Furthermore, the heat exchange medium is selected from at least one of pure water, aqueous ethylene glycol solution, or aqueous propylene glycol solution.

[0015] A second aspect of this invention provides a heating method for a liquid ammonia injector anti-icing heating device utilizing exhaust gas waste heat, applied to an ammonia-hydrogen engine. The outer wall of the liquid ammonia injector in the engine is covered with a heating jacket, and the engine exhaust manifold is connected to an exhaust gas heating module via an exhaust bypass valve. The method includes: Step 1: Obtain the real-time temperature of the nozzle area of ​​the liquid ammonia injector; compare the real-time temperature with a preset temperature threshold, which includes at least a low-temperature start-up threshold, a target stability threshold, and a high-temperature protection threshold; Step 2: Based on the comparison results in Step 1, generate a closed-loop temperature control adjustment command to adjust the opening degree of the exhaust gas bypass valve, the speed of the drive pump, and the opening degree of the second solenoid valve, so as to control the exhaust gas flow rate introduced into the exhaust gas heating module and the heat exchange medium flow rate through the heating jacket, thereby making the real-time temperature of the liquid ammonia injector nozzle area approach and maintain within the target stable threshold range. The closed-loop temperature control adjustment command includes: when the real-time temperature is less than the low-temperature start-up threshold and the engine has started running, the exhaust bypass valve opening is set to 85%-100%, the drive pump is set to 90%-100% of the rated speed, and the second solenoid valve opening is set to 90%-100% to maximize the exhaust heat input and heat exchange medium flow rate, and to rapidly heat the liquid ammonia injector. When the low temperature start-up threshold is less than or equal to the real-time temperature and less than the target stable threshold lower limit, the opening of the exhaust gas bypass valve is set to 65%-85%, the drive pump speed is adjusted to 70%-90% of the rated speed, and the opening of the second solenoid valve is maintained to accelerate the temperature rise. When the lower limit of the target stability threshold is less than or equal to the real-time temperature, the opening of the exhaust bypass valve is adjusted to 45%-65%, and the pump speed is adjusted to 50%-70% of the rated speed; and the opening of the second solenoid valve is maintained to maintain temperature stability. When the upper limit of the target stability threshold is less than the real-time temperature and less than the high temperature protection threshold, the opening of the exhaust bypass valve is adjusted to 25%-45%, the speed of the drive pump is adjusted to 25%-45% of the rated speed, and the opening of the second solenoid valve is reduced proportionally to the speed of the drive pump to maintain temperature stability. When the real-time temperature exceeds the high-temperature protection threshold, the exhaust gas bypass valve, drive pump, and second solenoid valve are controlled to be at their lowest opening / speed to minimize heating intensity and prevent overheating.

[0016] Furthermore, the heating method also includes a cooling step: During the heating process, when the real-time temperature of the nozzle area rises above 85°C and the engine load or ambient temperature drops to the preset conditions, the control module closes the second solenoid valve and opens the first and third solenoid valves. This allows the heat exchange medium to flow through the heat exchange medium cooling module for cooling before returning to the exhaust gas heating module, thus preventing overheating of the liquid ammonia injector.

[0017] Furthermore, the heating method also includes safety protection steps: During the heating process, the pressure and flow rate of the heat exchange medium in the medium circulation loop are monitored in real time by pressure and flow sensors. When any of the following fault conditions are detected, the control module immediately shuts down the heating device and issues an alarm: Case 1: The reading of the pressure sensor continuously or momentarily exceeds the preset pressure safety limit; Scenario 2: The reading of the pressure sensor remains below the preset pressure safety lower limit; Scenario 3: The reading of the flow sensor remains below the preset minimum safe flow threshold; Case 4: The temperature sensor fails.

[0018] The beneficial effects of this invention are as follows: The liquid ammonia injector anti-icing heating device utilizing exhaust gas waste heat described in this invention is not an independent after-treatment device, but a thermal management system integrated into the ammonia-hydrogen engine itself. Its core heat source comes from the high-temperature exhaust gas in the engine exhaust manifold. Compared with traditional electric heating solutions, it does not require additional engine power or battery power, and can achieve internal energy recycling. It not only solves the heating problem, but also reduces the power loss of engine accessories, which helps to improve the thermal efficiency of the ammonia-hydrogen engine. The heating method uses a temperature sensor embedded in the heating jacket to monitor the nozzle area temperature in real time. The PID control unit dynamically adjusts the drive pump speed and bypass valve opening according to the set target temperature, forming a fast and accurate closed-loop temperature control method. This active control strategy can ensure that the nozzle temperature is always within the ideal range, preventing low-temperature freezing and avoiding the risk of overheating caused by continuous heating, thus realizing intelligent thermal management. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the anti-icing heating device for liquid ammonia injectors utilizing waste heat from exhaust gas, as described in this invention. Figure 2 This is a partially enlarged schematic diagram of the fuel injector and heating jacket; Figure 3 This is a flowchart of the heating method for the liquid ammonia injector anti-icing heating device that utilizes the waste heat of exhaust gas.

[0020] Among them, 1: control module; 2: heating jacket; 3: liquid ammonia injector; 4: signal transmission line; 5: first solenoid valve; 6: heat exchange medium cooling module; 7: exhaust gas heating module; 8: PID control unit; 9: drive pump; 10: pressure sensor; 11: flow sensor; 12: second solenoid valve; 13: third solenoid valve; 14: temperature sensor; 15: gasket; 16: fastening bolt; 17: heating jacket inlet; 18: heating jacket outlet; 19: second heat exchange channel; 20: first branch; 21: second branch. Detailed Implementation

[0021] To make the objectives, technical solutions, beneficial effects, and significant advancements of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings provided in the examples of the present invention. Obviously, all 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.

[0022] In the description of this application, unless otherwise expressly specified and limited, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more; unless otherwise specified or explained, the terms "connected," "fixed," etc., should be interpreted broadly. For example, "connected" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0023] like Figure 1 As shown, a liquid ammonia injector anti-icing heating device utilizing waste heat from exhaust gas includes a control module 1, an exhaust gas heat extraction module 7, a heating jacket 2, a heat exchange medium cooling module 6, a drive pump 9, and a temperature control unit; the exhaust gas heat extraction module 7, the heating jacket 2, the first branch 20, and the second branch 21 form a medium circulation loop.

[0024] The medium circulation loop is as follows: the heat exchange medium from the exhaust gas heating exhaust gas ignition module 7 of the engine exhaust manifold flows through the first branch 20, the heating jacket 2, the second branch 21, and the heat exchange medium cooling module 6 in sequence through the second output end, and then flows into the heat exchange channel in the exhaust gas heating module 7 through the second input end. In this embodiment, the heat exchange medium in the circulation loop is water.

[0025] The exhaust gas heating module 7 includes a housing and a first heat exchange channel located inside the housing. The housing is provided with a first input end, a first output end, a second input end, and a second output end. The first input end and the first output end are arranged along the length of the exhaust gas heating module 7. The rear end of the engine exhaust manifold is connected to the first input end of the exhaust gas heating module 7 via a pipeline to heat the heat exchange medium in the first heat exchange channel inside the housing. The high-temperature exhaust gas from the engine is treated by an exhaust gas aftertreatment device from the first output end before being discharged to the outside. The exhaust gas aftertreatment device converts harmful pollutants produced after engine combustion into substances that are harmless or less harmful to the atmospheric environment through physical filtration and chemical reactions, thereby ensuring that vehicle emissions meet national and regional mandatory environmental protection regulations. Since the exhaust gas aftertreatment part is not the inventive point of this invention, it will not be described in detail here; any exhaust gas aftertreatment device that can achieve the above-mentioned purpose is acceptable. The second input end and the second output end are located on one side of the housing and between the first input end and the first output end, serving as the inlet and outlet of the first heat exchange channel. The exhaust gas heating module 7 is a wound-tube micro heat exchanger, with a high thermal conductivity metal S-shaped tube forming a first heat exchange channel inside the housing. The two ends of the first heat exchange channel are respectively connected to a second input end and a second output end. One end of the second input end is connected to one end of the first heat exchange channel, and the other end is connected to one end of the first branch 20, the other end of which is connected to the inlet of the heating jacket. One end of the second output end is connected to the other end of the first heat exchange channel, and the other end is connected to one end of the second branch 21, the other end of which is connected to the outlet of the heating jacket.

[0026] The first heat exchange channel is an S-shaped thin-walled tube, and the heat exchange medium is contained in the first heat exchange channel; when the exhaust gas passes through the exhaust gas heating module 7, it heats the heat exchange medium inside.

[0027] The heating sleeve 2 is a wraparound metal sleeve structure, fitted onto the outer surface of the liquid ammonia injector 3. It is secured to the heating sleeve 2 and the liquid ammonia injector 3 by fastening bolts 16, maintaining stable thermal contact. The liquid ammonia injector 3 is located on the cylinder head of the hydrogen-ammonia engine and is used to inject liquid ammonia directly into the combustion chamber at high speed.

[0028] like Figure 2As shown, the heating jacket 2 has a second heat exchange channel inside, used to accommodate the high-temperature heat exchange medium. The second heat exchange channel 19 is an annular high thermal conductivity metal heat pipe, and its main body surrounds the outer wall of the nozzle area of ​​the liquid ammonia injector 3. Furthermore, the inner wall of the second heat exchange channel 19 is provided with a capillary core structure, within which a sintered metal powder layer is provided. The sintered metal powder layer is a porous structure formed by high-temperature sintering of copper-based powder, with a porosity of 35%-45%. In another embodiment, the capillary core structure is a metal wire mesh, which is a 300-mesh stainless steel wire mesh layered and woven structure. The heating jacket inlet 17, located at the upper end of the heating jacket, receives the heat exchange medium from the first branch 20. As the heat exchange medium flows through the annular second heat exchange channel, it transfers the heat it carries to the nozzle of the liquid ammonia injector 3, which is tightly fitted to its inner side, via thermal conduction. The medium then flows from the heating jacket outlet 18, located at the lower end of the heating jacket 2, into the second branch 21 or is transferred to the heat exchange medium cooling module 6. An annular injector sealing gasket 15 is installed at the interface between the liquid ammonia injector 3 and the heating jacket 2 to seal and prevent gas leakage from the engine cylinder. The temperature sensor 14 is embedded in the outer wall of the heating jacket 2 and located on the injector surface near the nozzle needle valve. It is used to measure the nozzle surface temperature in real time and feed it back to the control module 1; the temperature sensor 14 is a thermistor. Because liquid ammonia has an extremely high latent heat of vaporization, continuous injection will cause the temperature of the metal around the nozzle to drop sharply, leading to condensation, frost, or even ice formation. Through the above heat exchange process, the nozzle surface temperature can be quickly raised to a stable range of 0-20 ℃, thereby effectively suppressing low-temperature icing and ensuring smooth injection and atomization quality.

[0029] The heat exchange medium cooling module 6 includes a shell and a third heat exchange channel located within the shell. The third heat exchange channel is also a thin-walled metal S-shaped tube. Cooling water within the third heat exchange channel cools the heat exchange medium inside the heat exchange medium cooling module 6. The inlet of the third heat exchange channel is connected to a second branch 21 via a first solenoid valve 5, and the outlet of the third heat exchange channel is connected to the second branch 21 via a third solenoid valve 13. A second solenoid valve 12 is also installed on the second branch 21, located between the first solenoid valve 5 and the third solenoid valve 13. All three solenoid valves (5, 12, and 13) are electrically connected to the control module 1, which controls the opening and closing of the pipeline by controlling their switching.

[0030] The first branch 20 is equipped with a temperature control unit and a drive pump 9. The temperature control unit includes a PID control unit 8, a pressure sensor 10, and a flow sensor 11. The drive pump 9, pressure sensor 10, and flow sensor 11 are all electrically connected to the PID control unit 8, which is electrically connected to the control module 1. The pressure sensor 10 and flow sensor 11 monitor the pressure and flow rate of the heat exchange medium flowing through it, and transmit the data to the control module 1 via the signal transmission line 4. The PID control unit 8 receives the control signal from the control module 1 and performs closed-loop regulation of the speed of the drive pump 9 to provide flow power for the heat exchange medium. It also has an internal storage tank for storing the liquid heat exchange medium.

[0031] The control module 1 is electrically connected to the ECU, and the control module 1 is connected to the PID control unit through the signal transmission line 4. The control module is used to receive signals from the pressure sensor 10, the flow sensor 11 and the temperature sensor in real time and output control commands, and to run the temperature control strategy according to the received signals.

[0032] like Figure 3 As shown, the heating method of the liquid ammonia injector anti-icing heating device utilizing waste heat from exhaust gas is as follows: The anti-icing heating device for the liquid ammonia injector is attached to an ammonia-hydrogen engine, which includes a cylinder liner, a cylinder head, and a piston. The space formed by the cylinder liner, cylinder head, and piston is a combustion chamber. The cylinder head is equipped with a spark plug, a liquid ammonia injector 3, a hydrogen injector, an intake manifold, and an exhaust manifold. The exhaust gas from the engine's exhaust manifold is connected to the exhaust gas heating module 7 via an exhaust bypass valve (not shown in the figure).

[0033] The outer surface of the liquid ammonia injector 3 is covered by the heating jacket 2, and the medium circulation loop of the liquid ammonia injector anti-icing heating device flows through the tail gas heating module 7, the heating jacket 2, the first branch 20 and the second branch 21.

[0034] Step 1: System Initialization. After the engine is ignited and started, the engine control unit (ECU) first reads the ambient temperature and engine coolant temperature and transmits them to the control module 1. The control module 1 receives the temperature from the temperature sensor 14, obtains the surface temperature of the liquid ammonia injector 3, and initializes the first solenoid valve 5, the second solenoid valve 12, the third solenoid valve 13, the drive pump 9, the temperature sensor 14, the pressure sensor 10, and the flow sensor 11, establishing communication with the control module 1. Step 2: Temperature sensor 14 collects the surface temperature of the liquid ammonia injector nozzle in real time (denoted as...). The temperature signal is fed back to the control module 1 in real time. The control module 1 presets three temperature thresholds as the judgment criteria for the control logic: a low-temperature start-up threshold, a target stability threshold range, and a high-temperature protection threshold. The low-temperature start-up threshold T1 is set to 20℃. Below this temperature, moisture in the air is easily condensed and frozen in the nozzle. The target stability threshold T2 is set to 55℃±10℃. This temperature threshold is higher than the freezing critical temperature but lower than the cooling water temperature of 90℃, avoiding heat transfer conflicts and being far away from the liquid ammonia decomposition temperature. The high-temperature protection threshold T3 is set to 75℃ to prevent the nozzle from overheating and causing premature vaporization of liquid ammonia, which would affect the spray atomization. The control module 1 compares the real-time temperature values ​​of the liquid ammonia injector 3 collected in real time by the temperature sensor 14 in the following order: low temperature start-up threshold, target stability threshold, and high temperature protection threshold. Step 3: Based on the comparison results of Step 2, operate the speed of the drive pump 9, the opening degree of the waste gas bypass valve, and the opening degree of the second solenoid valve 12, specifically including: The real-time temperature at the nozzle of the liquid ammonia injector When the engine is running and the low-temperature start-up threshold T1 is reached, an icing risk is identified. The exhaust bypass valve is opened at 85%-100% to maximize the introduction of high-temperature exhaust gas (300-500℃), allowing the exhaust gas from the engine exhaust manifold to flow through the exhaust gas heat transfer module 7. Simultaneously, the drive pump 9 is started at 90%-100% of its rated speed, and the second solenoid valve 12 is opened at 90%-100% to ensure that the heating jacket flow path is completely unobstructed and achieve efficient heat transfer. The medium circulation loop is started, and the exhaust gas from the engine flows through the exhaust gas heat transfer module 7, maximizing the circulation flow of the heat exchange medium and quickly transferring the waste heat of the exhaust gas (the exhaust gas temperature is usually 300-500℃, which can quickly increase the nozzle temperature). This allows the heat exchange medium to absorb the waste heat of the exhaust gas and raise its temperature, causing the nozzle temperature to quickly move away from the icing risk zone. After being heated, the heat exchange medium enters the heating jacket 2 located at the front end of the liquid ammonia injector 3 through the first branch 20. The heat of the exhaust gas is transferred to the nozzle area of ​​the liquid ammonia injector 3 through heat pipe conduction, thereby heating and de-icing the nozzle surface. When T1≤ <T2 lower limit (i.e., 20℃≤ <45℃), which is considered a slight risk of icing, requires continuous heating to approach the target range; adjust the opening of the exhaust bypass valve to 65%-85%, adjust the speed of the drive pump 9 to 70%-90% of the rated speed to accelerate the temperature rise and reduce the temperature difference with the target temperature; keep the opening of the second solenoid valve 12 at 90%-100% to ensure that the heating jacket flow path is completely unobstructed, and start the medium circulation loop; When T2 lower limit ≤ ≤T2 upper limit (i.e., 45℃≤ If the temperature is ≤65℃, it is determined to be in the target stable range. The opening of the waste gas bypass valve is adjusted to 45%-65%, the speed of the drive pump 9 is adjusted to 50%-70% of the rated speed to maintain a stable circulation of the heat exchange medium, and the opening of the second solenoid valve 12 is kept at 90%-100% to maintain a stable temperature by utilizing the waste heat of the exhaust gas. When T2 upper limit < ≤T3 (i.e., 65℃ < If the temperature is ≤75℃, it is determined that the temperature is close to the upper limit and the temperature rise needs to be actively suppressed; the opening of the exhaust bypass valve is adjusted to 25%-45% to significantly reduce the input of heat in the exhaust gas; the speed of the drive pump 9 is adjusted to 25%-45% of the rated speed to significantly reduce the flow of heat exchange medium; the opening of the second solenoid valve 12 is reduced proportionally to the speed of the drive pump (e.g., if the pump speed is 40%, the valve opening is 40%), and the flow of medium entering the heating jacket is throttled synchronously. when >T3 (i.e., >75℃) indicates a risk of overheating, requiring minimization of heating and enhanced heat dissipation; adjust the exhaust bypass valve opening to 15%-25% to minimize exhaust heat input; adjust the drive pump 9 speed to 20%-30% of its rated speed to maintain only the minimum medium circulation and prevent stagnation; reduce the opening of the second solenoid valve 12 proportionally to the drive pump speed (e.g., if the pump speed is 25%, then the valve opening is 25%) to minimize the heat exchange medium flowing to the heating jacket; The above temperature monitoring is continuously performed in a loop during the operation of the system, automatically adjusting the speed of the drive pump, the opening of the waste gas bypass valve and the second solenoid valve 12, thereby controlling the flow rate of the heat exchange medium and the amount of exhaust gas introduced, so that the injector temperature is maintained within the target range of 40-80 ℃. The heat exchange medium flows from the outlet of the heating jacket 2 through the second branch 21 and then returns to the exhaust gas heating module 7 to complete one heating cycle.

[0035] when If the temperature is >85℃ and the engine torque is <30% of the maximum torque or the ambient temperature is >35℃, close the second solenoid valve 12, stop the drive pump 9 from working, and open the first solenoid valve 5 and the third solenoid valve 13; so that the heat exchange medium flows from the outlet of the heating jacket 2 through the second branch 21, the first solenoid valve 5, the heat exchange medium cooling module 6, and the third solenoid valve 13 in sequence and then returns to the exhaust gas heating module 7 to prevent the liquid ammonia injector 3 from overheating.

[0036] During the heating cycle, pressure sensor 10 and flow sensor 11 transmit signals to control module 1 in real time via PID control unit 8 to monitor the circulation status of the heat exchange medium. The heating device is immediately shut down and an alarm signal is issued if any of the following conditions are detected: Scenario 1: When the pressure sensor 10 continuously or momentarily exceeds 120% of the preset working pressure; at this time, there may be a blockage in the medium circulation loop, accidental valve closure, excessive pump output, or excessive temperature causing the medium to vaporize. Scenario 2: The reading of pressure sensor 10 is consistently lower than 80% of the preset working pressure; in this case, there may be media leakage, drive pump 9 failure, or valve opening being too large. Scenario 3: The real-time measurement value of flow sensor 11 is consistently lower than the minimum safe flow threshold set by control module 1; in this case, there may be a blockage in the medium circulation loop, accidental valve closure, or a malfunction of the flow sensor itself. Scenario 4: Temperature sensor failure; In this case, the temperature sensor circuit may be disconnected, the PID control unit may receive out-of-range signals such as 0V, 5V or 0mA, or the received temperature sensor signal may exceed a reasonable range such as -50°C or 200°C, or the system operating conditions may change significantly after more than 40 seconds of constant temperature.

[0037] Through the above steps, the exhaust gas waste heat is used to directionally heat the fuel injector during engine operation, avoiding low-temperature icing caused by the latent heat of liquid ammonia vaporization, and improving the injection atomization quality and engine operation stability.

[0038] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is merely for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in the embodiments can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A liquid ammonia injector anti-icing heating device utilizing waste heat from exhaust gas, characterized in that, It includes a control module (1), an exhaust gas heating module (7), a heating jacket (2), and a heat exchange medium cooling module (6); the heating jacket (2) is fitted and heat-conductingly contacts the outer wall of the liquid ammonia injector (3) of the ammonia-hydrogen engine; the control module (1) is connected to the engine's ECU; and the exhaust manifold of the engine regulates the exhaust gas flow into the exhaust gas heating module (7) through an exhaust gas bypass valve; The exhaust gas heating module (7) is provided with a first heat exchange channel. The exhaust gas from the engine flows through the exhaust gas heating module (7) to heat up the heat exchange medium in the first heat exchange channel. The heat exchange medium cooling module (6) is provided with a third heat exchange channel, which uses cooling water to cool down the heat exchange medium in the third heat exchange channel. The heating jacket (2) is provided with a second heat exchange channel (19), the main body of which surrounds the nozzle area of ​​the liquid ammonia injector (3). The first heat exchange channel of the exhaust gas heating module (7), the second heat exchange channel (19) of the heating jacket (2) and the third heat exchange channel of the heat exchange medium cooling module (6) are connected in series through the first branch (20) and the second branch (21) to form a medium circulation loop; The inlet of the third heat exchange channel is connected to the second branch (21) through the first solenoid valve (5), and its outlet is connected to the second branch (21) through the third solenoid valve (13); a drive pump (9) is provided on the first branch. On the second branch (21), a second solenoid valve (12) is also provided between the first solenoid valve (5) and the third solenoid valve (13); the first solenoid valve (5), the second solenoid valve (12) and the third solenoid valve (13) are all electrically connected to the control module (1); The control module (1) dynamically adjusts the opening degree of the exhaust bypass valve, the second solenoid valve (12) and the speed of the drive pump (9) according to the temperature at the nozzle of the liquid ammonia injector (3), thereby adjusting the flow rate and speed of the heat exchange medium in the medium circulation loop, so that the engine can use the residual heat of the exhaust gas to maintain the temperature at the nozzle of the liquid ammonia injector at 40-80 ℃ during operation.

2. The anti-icing heating device for liquid ammonia injectors utilizing waste heat from exhaust gas according to claim 1, characterized in that, A temperature sensor (14) is provided on the inner wall of the heating jacket (2). The temperature sensor (14) is located at the nozzle of the liquid ammonia injector (3) and is used to measure and feed back the temperature of the nozzle area to the control module (1) in real time. The temperature sensor (14) is electrically connected to the control module (1).

3. The anti-icing heating device for liquid ammonia injectors utilizing waste heat from exhaust gas according to claim 1, characterized in that, A temperature control unit is also provided on the first branch (20). The temperature control unit includes a PID control unit (8) and a pressure sensor (10) and a flow sensor (11) provided on the first branch. The drive pump (9), pressure sensor (10) and flow sensor (11) are all electrically connected to the PID control unit (8). The PID control unit (8) receives the control signal from the control module (1) and performs closed-loop regulation on the speed of the drive pump (9).

4. The anti-icing heating device for liquid ammonia injectors utilizing waste heat from exhaust gas according to claim 1, characterized in that, The first and third heat exchange channels are S-shaped pipe discs respectively installed in the exhaust gas heat extraction module (7) and the heat exchange medium cooling module (6). The S-shaped pipes are selected from stainless steel thin-walled pipes or S-shaped metal pipes; the second heat exchange channel (19) is an annular metal pipe.

5. The anti-icing heating device for liquid ammonia injectors utilizing waste heat from exhaust gas according to claim 4, characterized in that, The material of the S-shaped metal tube is selected from one of the following: copper, copper alloy, aluminum, and aluminum alloy.

6. The anti-icing heating device for liquid ammonia injectors utilizing waste heat from exhaust gas according to claim 4, characterized in that, The inner wall of the second heat exchange channel (19) is provided with a capillary wick structure.

7. The anti-icing heating device for liquid ammonia injectors utilizing waste heat from exhaust gas according to claim 1, characterized in that, The heat exchange medium is selected from at least one of pure water, aqueous ethylene glycol solution, or aqueous propylene glycol solution.

8. The heating method of the liquid ammonia injector anti-icing heating device utilizing waste heat from exhaust gas according to any one of claims 1-7, characterized in that... The heating method is applied to an ammonia-hydrogen engine, wherein the outer wall of the liquid ammonia injector (3) of the engine is covered with a heating jacket (2), and the engine exhaust manifold is connected to the exhaust gas heating module (7) through an exhaust bypass valve. The method includes: Step 1: Use temperature sensor (14) to obtain the real-time temperature of the nozzle area of ​​the liquid ammonia injector (3); compare the real-time temperature with a preset temperature threshold, which includes at least a low temperature start-up threshold, a target stability threshold and a high temperature protection threshold; Step 2: Based on the comparison results in Step 1, generate a closed-loop temperature control adjustment command to adjust the opening degree of the waste gas bypass valve, the speed of the drive pump (9) and the opening degree of the second solenoid valve (12) to control the flow rate of the exhaust gas introduced into the exhaust gas heating module (7) and the flow rate of the heat exchange medium flowing through the heating jacket (2), so that the real-time temperature of the nozzle area of ​​the liquid ammonia injector (3) approaches and is maintained within the range of the target stable threshold. The closed-loop temperature control adjustment command includes: when the real-time temperature is less than the low temperature start threshold and the engine has started running, the exhaust bypass valve opening is set to 85%-100%, the drive pump (9) is set to 90%-100% of the rated speed, and the second solenoid valve (12) opening is set to 90%-100% to maximize the exhaust heat input and heat exchange medium flow rate, and to rapidly heat the liquid ammonia injector (3); When the low temperature start-up threshold is less than or equal to the real-time temperature and less than the target stable threshold lower limit, the opening of the waste gas bypass valve is set to 65%-85%, the speed of the drive pump (9) is adjusted to 70%-90% of the rated speed, and the opening of the second solenoid valve (12) is maintained to accelerate the temperature rise; When the lower limit of the target stability threshold is less than or equal to the real-time temperature, the opening of the waste gas bypass valve is adjusted to 45%-65%, and the speed of the drive pump (9) is adjusted to 50%-70% of the rated speed; and the opening of the second solenoid valve (12) is maintained to maintain temperature stability. When the upper limit of the target stable threshold is less than the real-time temperature and less than the high temperature protection threshold, the opening of the exhaust bypass valve is adjusted to 25%-45%, the speed of the drive pump (9) is adjusted to 25%-45% of the rated speed, and the opening of the second solenoid valve (12) is reduced proportionally to the speed of the drive pump to maintain temperature stability. When the real-time temperature is greater than the high temperature protection threshold, the exhaust gas bypass valve, drive pump (9) and second solenoid valve (12) are controlled to be in the lowest opening / speed state to minimize the heating intensity and prevent overheating.

9. The heating method according to claim 8, characterized in that... The heating method also includes a cooling step: During the heating process, when the real-time temperature of the nozzle area rises above 85°C and the engine load or ambient temperature drops to the preset conditions, the control module (1) closes the second solenoid valve (12), opens the first solenoid valve (5) and the third solenoid valve (13), so that the heat exchange medium flows through the heat exchange medium cooling module (6) for cooling, and then returns to the exhaust gas heating module (7) to prevent overheating of the liquid ammonia injector (3).

10. The heating method according to claim 8, characterized in that... The heating method also includes safety protection steps: During the heating process, the pressure and flow rate of the heat exchange medium in the medium circulation loop are monitored in real time by pressure sensor (10) and flow sensor (11); when any of the following fault conditions are detected, the control module (1) immediately shuts down the heating device and issues an alarm: The reading of the pressure sensor (10) continuously or momentarily exceeds the preset pressure safety limit; The reading of the pressure sensor (10) remains below the preset pressure safety limit; The reading of the flow sensor (11) remains below a preset minimum safe flow threshold; or The temperature sensor (14) failed.

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