A liquid ammonia-hydrogen-electric hybrid engine system and its operating method

Abstract

A liquid ammonia-hydrogen-electric hybrid engine system includes a dual direct-injection ammonia engine, a power battery, a liquid ammonia evaporator, and an ammonia partial catalytic cracking device; the dual direct-injection ammonia engine and the power battery provide power output simultaneously or selectively; the dual direct-injection ammonia engine has two fuel direct injection inlets, an air inlet, and an exhaust gas outlet, and the two fuel direct injection inlets are respectively connected to liquid ammonia and an ammonia-hydrogen-nitrogen mixture; the liquid ammonia evaporator vaporizes part of the liquid ammonia, and the resulting ammonia is input into the ammonia partial catalytic cracking device and cracked therein to obtain an ammonia-hydrogen-nitrogen mixture; a portion of the output of the dual direct-injection ammonia engine is converted into electrical energy and stored in the power battery, which provides electrical energy for an electric auxiliary heat cold start device, which is used to achieve cold start of the liquid ammonia evaporator and the ammonia partial catalytic cracking device. The present invention can control pollutant emissions at a low level and solve the problem of liquid ammonia as a fuel having poor ignition and combustion characteristics.

Description

Technical Field

[0001] The present invention relates to an ammonia hybrid engine system, and in particular to a liquid ammonia-hydrogen-electric hybrid engine system and an operating method thereof. Background Art

[0002] The use of carbon-free fuels such as hydrogen and ammonia in the automotive sector can reduce CO2 emissions. Hydrogen can be stored and transported in high-pressure cylinders, but this is expensive and has a short range.

[0003] Ammonia can be synthesized from hydrogen as a raw material, and its storage and transportation pressure and temperature parameters are low, resulting in low cost. When using ammonia as a fuel in engines, direct injection of liquid ammonia is often used to achieve high-power combustion to increase engine power. However, due to the low laminar flame speed and high minimum ignition energy of liquid ammonia combustion, its combustion stability is poor. Summary of the Invention

[0004] To overcome the shortcomings of the aforementioned prior art, the present invention aims to provide a liquid ammonia-hydrogen-electric hybrid engine system and its operating method. This system utilizes a liquid ammonia vaporization process, online partial cracking to produce hydrogen, and the use of an ammonia-hydrogen-nitrogen mixture to improve combustion. This system, firstly, addresses the stability issues associated with liquid ammonia injection combustion. Secondly, coupling a power battery with an electric auxiliary heat cold start device solves the engine cold start problem. Thirdly, it utilizes waste heat from exhaust gas and cooling water to improve system efficiency. Furthermore, the present invention utilizes a central control unit to select operating modes and control the ammonia cracking flow rate and cracking volume ratio, intelligently controlling stable combustion, nitrogen oxide (NOx), and unburned ammonia-hydrogen emissions, achieving zero carbon emissions while simultaneously achieving optimal operating conditions.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A liquid ammonia-hydrogen-electric hybrid engine system includes a dual direct-injection ammonia engine, a power battery, a liquid ammonia evaporator, and an ammonia partial catalytic cracking device; the dual direct-injection ammonia engine and the power battery provide power output simultaneously or selectively;

[0007] The dual direct injection ammonia engine has two fuel direct injection inlets, one air inlet and one exhaust gas outlet, wherein the two fuel direct injection inlets are connected to liquid ammonia and ammonia-hydrogen-nitrogen mixed gas respectively;

[0008] The liquid ammonia evaporator vaporizes part of the liquid ammonia, and the obtained ammonia gas is fed into the ammonia partial catalytic cracking device and cracked therein to obtain the ammonia-hydrogen-nitrogen mixed gas;

[0009] Part of the output of the dual direct injection ammonia engine is converted into electrical energy and stored in a power battery. The power battery provides electrical energy for the electric auxiliary heat cold starting device, and the electric auxiliary heat cold starting device is used to achieve cold starting of the liquid ammonia evaporator and the ammonia partial catalytic cracking device.

[0010] In one embodiment, the dual direct injection ammonia engine has two fuel supply modes, namely, a liquid ammonia direct injection mode for increasing power and an ammonia-hydrogen-nitrogen mixed gas direct injection mode, in which hydrogen is used as an oxidant to improve combustion.

[0011] In one embodiment, the liquid ammonia-hydrogen-electric hybrid engine system further includes: a liquid ammonia tank, a liquid ammonia pump, and an ammonia-hydrogen gas compressor;

[0012] The two direct fuel injection inlets are respectively connected to the liquid ammonia pump and the ammonia-hydrogen gas compressor; the liquid ammonia pump is connected to one outlet of the liquid ammonia tank, and the other outlet of the liquid ammonia tank is connected to the liquid ammonia inlet of the liquid ammonia evaporator; the ammonia-hydrogen gas compressor is connected to the mixed gas outlet of the ammonia partial catalytic cracking unit.

[0013] In one embodiment, the liquid ammonia-hydrogen-electric hybrid engine system further comprises: an exhaust gas heat exchanger;

[0014] The exhaust gas outlet of the dual direct injection ammonia engine is connected to the heat source inlet of the exhaust gas heat exchanger, and the heat source outlet of the exhaust gas heat exchanger is connected to the selective catalytic reduction device and the catalytic oxidation device in sequence; the exhaust gas heat absorbed by the exhaust gas heat exchanger is transferred to the liquid ammonia evaporator and the ammonia partial catalytic cracking device respectively, providing heat for the gasification and cracking of the liquid ammonia.

[0015] In one embodiment, the liquid ammonia-hydrogen-electric hybrid engine system further comprises: a cooling water heat exchanger;

[0016] The heat source inlet of the cooling water heat exchanger is connected to the cooling water outlet of the cooling water jacket of the dual direct injection ammonia engine. The waste heat of the cooling water absorbed by the cooling water heat exchanger is transferred to the liquid ammonia evaporator and the ammonia partial catalytic cracking device respectively, providing heat for the gasification and cracking of liquid ammonia.

[0017] In one embodiment, the liquid ammonia-hydrogen-electric hybrid engine system further includes: a central control unit;

[0018] The central control unit centrally controls various fuel supply components, valves, sensors, heat transmission, and detects the composition and content of exhaust emissions.

[0019] In one embodiment, the fuel and air supply amounts of the dual direct injection ammonia engine are controlled, wherein the equivalence ratio is controlled to be 1.15, liquid ammonia is directly injected into the cylinder, and gaseous ammonia is controlled to have a cracking volume ratio of 0-30% through the ammonia partial catalytic cracking device.

[0020] The operating method of the liquid ammonia-hydrogen-electric hybrid engine system of the present invention includes:

[0021] When the dual direct injection ammonia engine is started, the power battery provides electrical energy to the electric auxiliary heat cold start device, supplies heat to the liquid ammonia evaporator and the ammonia partial catalytic cracking device, supplies liquid ammonia to the liquid ammonia evaporator to evaporate and vaporize under heat, and then passes into the ammonia partial catalytic cracking device to partially crack into an ammonia-hydrogen-nitrogen mixture. The ammonia-hydrogen-nitrogen mixture is directly injected into the dual direct injection ammonia engine for ignition. After ignition, liquid ammonia is directly injected into the dual direct injection ammonia engine for combustion. During stable operation, the power proportion of the ammonia-hydrogen-nitrogen mixture injection is controlled within 10%;

[0022] When unstable combustion of liquid ammonia occurs, the liquid ammonia evaporator and the ammonia partial catalytic cracking device are controlled according to the received unstable combustion signal to increase the flow rate of ammonia vaporized and cracked and the ammonia cracking volume ratio, thereby increasing the hydrogen ratio in the ammonia-hydrogen-nitrogen mixture and improving combustion stability. At this time, the power ratio of the ammonia-hydrogen-nitrogen mixture injection is controlled within 20%, of which the hydrogen volume ratio is controlled within 50%;

[0023] When outputting power, the dual direct injection ammonia engine and the power battery provide power output simultaneously or selectively, and the dual direct injection ammonia engine generates electricity to provide electrical energy to the power battery.

[0024] In one embodiment, after the engine is started, the exhaust gas heat exchanger is used to recover the heat from the combustion exhaust gas and transfer it to the liquid ammonia evaporator and the ammonia partial catalytic cracking unit respectively;

[0025] The cooling water heat exchanger is used to recover the heat in the cooling water of the dual direct injection ammonia engine and transfer it to the liquid ammonia evaporator and the ammonia partial catalytic cracking unit respectively.

[0026] In one embodiment, the ammonia power of the dual direct injection ammonia engine is in the range of 100-300 kW, and the thermal efficiency of the entire system is close to 60%.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] Compared with the existing technology, the liquid ammonia-hydrogen-electric hybrid engine system of the present invention improves combustion stability by vaporizing liquid ammonia and partially cracking the ammonia through an ammonia catalytic cracking device to form an ammonia-hydrogen mixed gas. By coupling the power battery, an electric auxiliary heat cold start device is used to solve the cold start problem of the liquid ammonia evaporator and the ammonia partial catalytic cracking device. The system efficiency is improved by utilizing the waste heat of exhaust gas and cooling water. The present invention can also select the operating mode and control the flow rate and cracking volume ratio of ammonia cracking through a central control unit, intelligently control stable combustion, nitrogen oxides and unburned ammonia hydrogen emissions, achieve zero carbon emissions, and achieve the optimal operating state. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the system structure of the present invention. DETAILED DESCRIPTION

[0030] The embodiments of the present invention are described in detail below with reference to the accompanying drawings and examples.

[0031] Traditional ammonia fuel engines have poor combustion stability and low overall system efficiency. To this end, the present invention provides a liquid ammonia-hydrogen-electric hybrid engine system, which uses an "ammonia-hydrogen co-combustion" concept to regulate the ammonia flame with hydrogen. On the one hand, the high activity of hydrogen promotes the stability of ammonia combustion. On the other hand, hydrogen is obtained by cracking ammonia downstream, and combustion does not require strict requirements on the purity of hydrogen, ultimately achieving decarbonization of the fuel system.

[0032] like Figure 1 As shown, the present invention is a liquid ammonia-hydrogen-electric hybrid engine system, which mainly includes a dual direct-injection ammonia engine 3, a power battery 4, a liquid ammonia evaporator 10, and an ammonia partial catalytic cracking unit 11. The power of the dual direct-injection ammonia engine 3 and the power battery 4 are connected in parallel, and can provide power output 5 simultaneously or selectively.

[0033] The dual direct-injection ammonia engine 3 of the present invention has two direct fuel injection inlets: a liquid fuel direct injection inlet and a gaseous fuel direct injection inlet, which are connected to liquid ammonia and an ammonia-hydrogen-nitrogen mixture, respectively. Accordingly, it has two fuel supply modes: liquid ammonia direct injection mode and ammonia-hydrogen-nitrogen mixture direct injection mode. The liquid ammonia direct injection mode can increase power, while the hydrogen injected in the ammonia-hydrogen-nitrogen mixture direct injection mode can serve as an oxidant to improve combustion. The dual direct-injection ammonia engine 3 also has an air inlet for injecting air and an exhaust outlet for discharging exhaust gas.

[0034] The liquid ammonia evaporator 10 is a device that uses heat energy to evaporate and gasify liquid ammonia. The ammonia gas obtained is sent to the ammonia partial catalytic cracking device 11, where the ammonia gas is cracked to obtain an ammonia-hydrogen-nitrogen mixed gas.

[0035] Specifically, the present invention injects a portion of liquid ammonia directly into the dual direct-injection ammonia engine 3, and then vaporizes and catalytically cracks another portion of the liquid ammonia to produce an ammonia-hydrogen-nitrogen mixed gas. This mixed gas is then injected into the dual direct-injection ammonia engine 3, utilizing the mixed gas for ignition and improved combustion stability. This invention can control pollutant emissions to a low level while addressing the issue of poor combustion characteristics associated with liquid ammonia as a fuel.

[0036] The power battery 4 of the present invention can be charged using external electricity, or it can convert a portion of the energy output by the dual direct-injection ammonia engine 3 into electrical energy and store it in the power battery 4. In addition to providing power output 5, the power battery 4 can also provide electricity to the electric auxiliary heat cold starting device 13, which can achieve a cold start of the liquid ammonia evaporator 10 and the ammonia partial catalytic cracking device 11.

[0037] Through combination, the system of the present invention has multiple power output forms, namely direct output from the dual direct injection ammonia engine 3, direct output from the power battery 4, and coupled output from the dual direct injection ammonia engine 3 and the power battery 4. The power of the power battery 4 can be generated by the dual direct injection ammonia engine 3 and the charging input.

[0038] In the embodiment of the present invention, continue to refer to Figure 1 The liquid ammonia-hydrogen-electric hybrid engine system may also include: a liquid ammonia tank 1, a liquid ammonia pump 2 and an ammonia-hydrogen gas compressor 12.

[0039] The liquid ammonia tank 1 is used to store and provide the liquid ammonia required by the system. It has two outlets. One outlet is connected to the liquid fuel direct injection inlet of the dual direct-injection ammonia engine 3 via a liquid ammonia pump 2, where it is pressurized and injected with liquid ammonia. The other outlet is connected to the liquid ammonia evaporator 10, which provides liquid ammonia for evaporation. The ammonia-hydrogen gas compressor 12 is connected to the mixed gas output pipeline of the ammonia partial catalytic cracking unit 11, and the resulting ammonia-hydrogen-nitrogen mixed gas is pressurized and injected into the dual direct-injection ammonia engine 3.

[0040] That is, the dual direct-injection ammonia engine 3 of the present invention has two fuel sources. One is to directly inject liquid ammonia from the liquid ammonia tank 1 directly into the engine by pressurizing the liquid ammonia pump 2. The other is to vaporize the liquid ammonia in the liquid ammonia evaporator 10, partially crack it through the ammonia partial catalytic cracking unit 11 to form an ammonia-hydrogen-nitrogen mixed gas, and then pass it through the ammonia-hydrogen gas compressor 12 before direct injection.

[0041] In the embodiment of the present invention, continue to refer to Figure 1 The liquid ammonia-hydrogen-electric hybrid engine system may further include an exhaust gas heat exchanger 6. The exhaust gas heat exchanger 6 is used to recover the exhaust waste heat of the dual direct injection ammonia engine 3 and provide it to the liquid ammonia evaporation and catalytic cracking process.

[0042] Specifically, the heat source inlet of the exhaust gas heat exchanger 6 is connected to the exhaust gas outlet of the dual direct injection ammonia engine 3. The heat source outlet of the exhaust gas heat exchanger 6 is then connected to a selective catalytic reduction device 7 and a catalytic oxidation device 8. The exhaust gas after heat exchange is discharged to the selective catalytic reduction device 7 and then to the catalytic oxidation device 8. The selective catalytic reduction device 7 and the catalytic oxidation device 8 are used to treat the exhaust gas after heat exchange so that the exhaust gas finally discharged from the system meets environmental protection requirements. Specifically, the selective catalytic reduction device 7 converts nitrogen oxides contained in the exhaust gas into nitrogen with a conversion efficiency of 100%. The catalytic oxidation device 8 oxidizes unburned ammonia and hydrogen in the exhaust gas into nitrogen and water with a conversion efficiency of 100%. The final exhaust gas is mainly composed of nitrogen and water vapor, achieving zero-carbon and pollution-free emissions. The exhaust gas heat exchanger 6 has two cold source outlets, which are respectively connected to the liquid ammonia evaporator 10 and the ammonia partial catalytic cracking device 11. The exhaust gas heat absorbed by the cold source is transferred to these two devices, providing heat for the vaporization and cracking of the liquid ammonia.

[0043] In the embodiment of the present invention, continue to refer to Figure 1 The liquid ammonia-hydrogen-electric hybrid engine system may further include a cooling water heat exchanger 9. The cooling water heat exchanger 9 is used to recover the cooling water heat of the dual direct injection ammonia engine 3 and provide it to the liquid ammonia evaporation and catalytic cracking process.

[0044] Specifically, the heat source inlet of the cooling water heat exchanger 9 is connected to the cooling water outlet of the cooling water jacket of the dual direct injection ammonia engine 3, and the cold source outlet of the cooling water heat exchanger 9 is connected to the liquid ammonia evaporator 10 and the ammonia partial catalytic cracking device 11 respectively, so that the cooling water heat absorbed by the cold source is transferred to these two devices, providing heat for the gasification and cracking of liquid ammonia.

[0045] Therefore, the present invention provides heat for the liquid ammonia evaporator 10 and the ammonia partial catalytic cracking unit 11 in three ways. During a cold start, heat is provided by an electric auxiliary heat cold start unit 13 driven by the power battery 4. When the dual direct-injection ammonia engine 3 is operating, waste heat from the exhaust gas is supplied to the liquid ammonia evaporator 10 and the ammonia partial catalytic cracking unit 11, respectively, via the exhaust gas heat exchanger 6. Waste heat from the cooling water of the dual direct-injection ammonia engine 3 is supplied to the liquid ammonia evaporator 10 and the ammonia partial catalytic cracking unit 11, respectively, via the cooling water heat exchanger 9. This waste heat utilization improves the thermal efficiency of the system.

[0046] In the embodiment of the present invention, continue to refer to Figure 1The liquid ammonia-hydrogen-electric hybrid engine system may also include a central control unit 14. This central control unit 14 is the master control unit, capable of centrally controlling various fuel supply components, valves, sensors, heat transfer, and detecting the composition and content of exhaust emissions. This embodiment incorporates automatic control, namely the central control unit 14. By detecting exhaust gas composition and content, the central control unit 14 adjusts the supply of each fuel to achieve optimal thermal efficiency and low emissions for the dual direct injection ammonia engine 3.

[0047] For example, the central control unit 14 can control the fuel and air supply to the dual direct-injection ammonia engine 3, with an equivalence ratio of approximately 1.15. Liquid ammonia is directly injected into the cylinders, while gaseous ammonia is cracked by the ammonia partial catalytic cracking unit 11 at a volume ratio of 0-30%. Under these conditions, the system can achieve optimal operation. The ammonia power output of the dual direct-injection ammonia engine 3 ranges from 100-300 kW, and the overall system thermal efficiency is close to 60%.

[0048] The operating method of the liquid ammonia-hydrogen-electric hybrid engine system of the present invention includes:

[0049] When the dual direct injection ammonia engine 3 is started, the power battery 4 provides electric energy to the electric auxiliary heat cold start device 13, supplies heat to the liquid ammonia evaporator 10 and the ammonia partial catalytic cracking device 11, and the liquid ammonia tank 1 supplies liquid ammonia to the liquid ammonia evaporator 10 so that it evaporates and vaporizes under heat, and passes into the ammonia partial catalytic cracking device 11 to partially crack into an ammonia-hydrogen-nitrogen mixture. The ammonia-hydrogen-nitrogen mixture is directly injected into the dual direct injection ammonia engine 3 through the ammonia-hydrogen gas compressor 12. The ignition energy and stability are reduced by hydrogen. After ignition, the liquid ammonia is pressurized and directly injected from the liquid ammonia tank 1 through the liquid ammonia pump 2 to the dual direct injection ammonia engine 3 for combustion. During stable operation, the power proportion of the ammonia-hydrogen-nitrogen mixture injection is controlled within 10%.

[0050] After the engine starts, to achieve heat recycling, the combustion exhaust gas passes through the exhaust gas heat exchanger 6, which recovers heat from the combustion exhaust gas and transfers it to the liquid ammonia evaporator 10 and the ammonia partial catalytic cracking unit 11, respectively, achieving cascade energy utilization. The cooling water in the cooling water jacket of the dual direct injection ammonia engine 3 passes through the cooling water heat exchanger 9, which recovers heat from the cooling water in the dual direct injection ammonia engine 3 and transfers it to the liquid ammonia evaporator 10 and the ammonia partial catalytic cracking unit 11, respectively, achieving cascade energy utilization. The exhaust gas heat exchanger 6 and the cooling water heat exchanger 9 can be used simultaneously or alternatively.

[0051] When unstable liquid ammonia combustion occurs, the central control unit 14 controls the liquid ammonia evaporator 10 and the ammonia partial catalytic cracking unit 11 based on the unstable combustion signal received. This increases the flow rate of ammonia vaporized and cracked, as well as the cracked ammonia volume ratio. This increases the hydrogen content in the ammonia-hydrogen-nitrogen mixture, improving combustion stability and achieving the goal of improving combustion stability. At this time, the power contribution of the ammonia-hydrogen-nitrogen mixture injection is controlled within 20%, with the hydrogen volume ratio controlled within 50%.

[0052] When outputting power, the dual direct-injection ammonia engine 3 and the power battery 4 can simultaneously or selectively provide power output 5 in various strategies. A portion of the output of the dual direct-injection ammonia engine 3 is used for work, while a portion is converted into electrical energy and stored in the power battery 4. Under low operating conditions, the power battery 4 can utilize the waste heat from the dual direct-injection ammonia engine 3 via the electric auxiliary heat cold start device 13 to provide heat to the liquid ammonia evaporator 10 and the ammonia partial catalytic cracking unit 11. A coupled control strategy for the waste heat from the dual direct-injection ammonia engine 3 and the electric auxiliary heat is provided by the central control unit 14.

[0053] In summary, this system can improve combustion stability by vaporizing liquid ammonia and partially cracking the ammonia online through an ammonia catalytic cracking unit to form an ammonia-hydrogen mixture. By coupling the power battery system, on the one hand, the cold start problem of the liquid ammonia evaporator and the ammonia partial catalytic cracking unit is solved through the electric auxiliary heat cold start device. The waste heat utilization of exhaust gas and cooling water improves the system efficiency. The present invention can also select the operating mode and control the flow rate and cracking volume ratio of ammonia cracking through a central control unit, intelligently control stable combustion, nitrogen oxides and unburned ammonia-hydrogen emissions, achieve zero carbon emissions, and achieve a more optimal operating state.

[0054] The above are only preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes based on the technical solution and invention concept of the present invention within the scope disclosed by the present invention, which falls within the scope of protection of the present invention.

Claims

1. A method for operating a liquid ammonia-hydrogen-electric hybrid engine system, the liquid ammonia-hydrogen-electric hybrid engine system comprising a dual direct-injection ammonia engine (3), a power battery (4), a liquid ammonia evaporator (10), and an ammonia partial catalytic cracking device (11); the dual direct-injection ammonia engine (3) and the power battery (4) provide power output (5) simultaneously or selectively; The dual direct injection ammonia engine (3) has two fuel direct injection inlets, an air inlet and an exhaust gas outlet, wherein the two fuel direct injection inlets are respectively connected to liquid ammonia and an ammonia-hydrogen-nitrogen mixed gas; The liquid ammonia evaporator (10) vaporizes part of the liquid ammonia, and the obtained ammonia gas is fed into the ammonia partial catalytic cracking device (11) and cracked therein to obtain the ammonia-hydrogen-nitrogen mixed gas; A portion of the output of the dual direct injection ammonia engine (3) is converted into electrical energy and stored in a power battery (4). The power battery (4) provides electrical energy for an electric auxiliary heat cold starting device (13). The electric auxiliary heat cold starting device (13) is used to achieve a cold start of the liquid ammonia evaporator (10) and the ammonia partial catalytic cracking device (11); Its characteristics are: When the dual direct injection ammonia engine (3) is started, the power battery (4) provides electric energy to the electric auxiliary heat cold start device (13), supplies heat to the liquid ammonia evaporator (10) and the ammonia partial catalytic cracking device (11), supplies liquid ammonia to the liquid ammonia evaporator (10) to evaporate and vaporize under heat, and passes into the ammonia partial catalytic cracking device (11) to partially crack into an ammonia hydrogen nitrogen mixed gas, and the ammonia hydrogen nitrogen mixed gas is directly injected into the dual direct injection ammonia engine (3) for ignition. After ignition, liquid ammonia is directly injected into the dual direct injection ammonia engine (3) for combustion. During stable operation, the power proportion of the ammonia hydrogen nitrogen mixed gas injection is controlled within 10%; When unstable combustion of liquid ammonia occurs, the liquid ammonia evaporator (10) and the ammonia partial catalytic cracking device (11) are controlled according to the received unstable combustion signal to increase the flow rate of ammonia gas vaporized and cracked and the ammonia cracking volume ratio, thereby increasing the hydrogen ratio in the ammonia-hydrogen-nitrogen mixed gas and improving the combustion stability; At this time, the power ratio of the ammonia-hydrogen-nitrogen mixture injection is controlled within 20%, among which the hydrogen volume ratio is controlled within 50%; When outputting power, the dual direct injection ammonia engine (3) and the power battery (4) provide power output (5) simultaneously or selectively, and the dual direct injection ammonia engine (3) generates electricity to provide electric energy to the power battery (4).

2. The working method according to claim 1, characterized in that: After the engine is started, the heat in the combustion exhaust gas is recovered by the exhaust gas heat exchanger (6) and transferred to the liquid ammonia evaporator (10) and the ammonia partial catalytic cracking device (11) respectively; The cooling water heat exchanger (9) is used to recover heat from the cooling water of the dual direct injection ammonia engine (3), and the heat is transferred to the liquid ammonia evaporator (10) and the ammonia partial catalytic cracking device (11) respectively.

3. The working method according to claim 1, characterized in that: The ammonia power of the dual direct injection ammonia engine (3) ranges from 100 to 300 kW, and the thermal efficiency of the entire system is close to 60%.

4. The working method according to claim 1, characterized in that: The dual direct injection ammonia engine (3) has two fuel supply modes, namely a liquid ammonia direct injection mode for increasing power and an ammonia-hydrogen-nitrogen mixed gas direct injection mode, in which hydrogen is used as a combustion aid to improve combustion.

5. The working method according to claim 1, characterized in that: The liquid ammonia-hydrogen-electric hybrid engine system further comprises: a liquid ammonia tank (1), a liquid ammonia pump (2) and an ammonia-hydrogen gas compressor (12); The two direct fuel injection inlets are connected to the liquid ammonia pump (2) and the ammonia-hydrogen gas compressor (12) respectively; the liquid ammonia pump (2) is connected to one outlet of the liquid ammonia tank (1); the other outlet of the liquid ammonia tank (1) is connected to the liquid ammonia inlet of the liquid ammonia evaporator (10); and the ammonia-hydrogen gas compressor (12) is connected to the mixed gas outlet of the ammonia partial catalytic cracking device (11).

6. The working method according to claim 4 or 5, characterized in that: The liquid ammonia-hydrogen-electric hybrid engine system further includes: an exhaust gas heat exchanger (6); The exhaust gas outlet of the dual direct injection ammonia engine (3) is connected to the heat source inlet of the exhaust gas heat exchanger (6), and the heat source outlet of the exhaust gas heat exchanger (6) is connected to the selective catalytic reduction device (7) and the catalytic oxidation device (8) in sequence; the exhaust gas heat absorbed by the exhaust gas heat exchanger (6) is transferred to the liquid ammonia evaporator (10) and the ammonia partial catalytic cracking device (11) respectively, to provide heat for the gasification and cracking of the liquid ammonia.

7. The working method according to claim 6, characterized in that: The liquid ammonia-hydrogen-electric hybrid engine system further comprises: a cooling water heat exchanger (9); The heat source inlet of the cooling water heat exchanger (9) is connected to the cooling water outlet of the cooling water jacket of the dual direct injection ammonia engine (3). The waste heat of the cooling water absorbed by the cooling water heat exchanger (9) is respectively transferred to the liquid ammonia evaporator (10) and the ammonia partial catalytic cracking device (11), thereby providing heat for the vaporization and cracking of the liquid ammonia.

8. The working method according to claim 7, characterized in that: The liquid ammonia-hydrogen-electric hybrid engine system further includes: a central control unit (14); The central control unit (14) uniformly controls various fuel supply components, valves, sensors, various heat transmissions, and detects the composition and content of exhaust emissions.

9. The working method according to claim 1, characterized in that: The fuel and air supply amounts of the dual direct injection ammonia engine (3) are controlled, wherein the equivalence ratio is controlled to be 1.15, liquid ammonia is directly injected into the cylinder, and gaseous ammonia is controlled to have a cracking volume ratio of 0-30% through the ammonia partial catalytic cracking device (11).

Images