Ammonia hydrogen engine-fuel cell hybrid system waste heat recovery device and control method

Abstract

The application discloses an ammonia-hydrogen engine-fuel cell hybrid system waste heat recovery device and a control method, and belongs to the technical field of hybrid power vehicle power systems. The device comprises a high-temperature stage and a low-temperature stage organic Rankine cycle system, a heat pump system, a fuel cell cooling system, a condensation heat dissipation system and a fuel supply circuit. The high-temperature stage cycle recovers high heat of engine exhaust gas, and the low-temperature stage cycle recovers low heat of cylinder liner water and fuel cell coolant; the heat pump system has the functions of fuel cell heating and waste heat taste improvement; the condensation heat dissipation system condenses the working medium while its waste heat is used to evaporate liquid ammonia in the fuel supply circuit. The control method intelligently switches three waste heat recovery modes of pure engine, pure fuel cell and hybrid drive according to the required power, the fuel cell temperature and the ambient temperature, and dynamically controls each subsystem. The application realizes efficient cascade recovery and comprehensive utilization of waste heat, and significantly improves the vehicle energy utilization rate, the thermal efficiency and the system compactness.

Description

Technical Field

[0001] This invention belongs to the field of waste heat recovery technology for hybrid vehicle power systems, specifically relating to a waste heat recovery device and control method for an ammonia-hydrogen engine-fuel cell hybrid system. Background Technology

[0002] Driven by both energy structure transformation and environmental protection, hybrid vehicles have become an important technological development direction in the transportation sector due to their advantages of high energy efficiency and low emissions. To further achieve near-zero carbon emissions, hybrid power systems that combine clean hydrogen-oxygen fuel cells with zero-carbon fuel-driven ammonia-hydrogen engines offer a promising power solution for hybrid vehicles. This system can flexibly adjust power output according to operating conditions, effectively reducing energy consumption.

[0003] However, in the actual operation of hybrid vehicles, both the electrochemical reaction of the fuel cell and the combustion process of the ammonia-hydrogen engine generate a large amount of waste heat. These heat sources vary in temperature, ranging from tens of degrees Celsius in cylinder liner water to hundreds of degrees Celsius in engine exhaust gas, and are dispersed and dynamically change with the vehicle's operating mode. Currently, most waste heat management methods for hybrid vehicles still use separate cooling circuits, directly releasing waste heat into the environment. This not only causes significant energy waste and limits further improvement in vehicle energy efficiency, but also fails to effectively utilize waste heat to serve other vehicle systems such as cabin heating and fuel pretreatment.

[0004] In particular, under the complex multi-mode switching conditions of hybrid vehicles, such as pure electric drive, hybrid drive, and engine direct drive, traditional single waste heat recovery systems struggle to dynamically adapt to changes in heat source conditions and vehicle thermal demands. This results in problems such as low recovery efficiency, poor system coupling, and the inability to achieve energy cascading and intelligent allocation. Therefore, developing an integrated system highly compatible with ammonia-hydrogen engine-fuel cell hybrid vehicles, capable of efficient, dynamic recovery and comprehensive utilization of multi-grade waste heat, is urgently needed and of great significance for deeply exploring the energy-saving potential of vehicles and improving driving range and economy. Summary of the Invention

[0005] To address the aforementioned problems in existing technologies, this invention provides a waste heat recovery device and control method for an ammonia-hydrogen engine-fuel cell hybrid system. Based on the organic Rankine cycle principle, it employs a high- and low-temperature dual Rankine organic cycle to utilize the heat in the ammonia-hydrogen engine and fuel cell in a cascade manner. By absorbing residual heat from the exhaust gas of the ammonia-hydrogen engine, cylinder liner water, and fuel cell coolant, it can fully cool the ammonia-hydrogen engine and fuel cell, and convert thermal energy into electrical energy. This achieves full recovery of waste heat from the power system, reduces energy consumption, improves thermal efficiency, and reduces environmental pollution.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] As a first aspect of the present invention, a waste heat recovery device for an ammonia-hydrogen engine-fuel cell hybrid system is provided, comprising a fuel cell, an ammonia-hydrogen engine, a high-temperature organic Rankine cycle system, a low-temperature organic Rankine cycle system, a fuel cell cooling system, a heat pump system, a power generation and energy storage system, a condensation and heat dissipation system, and a fuel supply circuit; the high-temperature organic Rankine cycle system is used to absorb heat from the exhaust gas of the ammonia-hydrogen engine, and the low-temperature organic Rankine cycle system is used to absorb heat from the exhaust gas of the ammonia-hydrogen engine, cylinder liner water, and fuel cell coolant; the power generation and energy storage system is used to respectively recover the heat absorbed by the high-temperature organic Rankine cycle system and the low-temperature organic Rankine cycle system. It can be converted into electrical energy and stored in the power battery, which in turn provides power to the electric heater in the fuel supply circuit; the heat pump system has a fuel cell heating mode and a low-temperature organic Rankine cycle heating mode; the fuel cell cooling system has a fuel cell-air heat exchange mode, a fuel cell-heat pump heat exchange mode, and a fuel cell-low-temperature organic Rankine cycle heat exchange mode; when the ammonia-hydrogen engine is working, the fuel supply circuit is responsible for providing hydrogen and ammonia for combustion to the ammonia-hydrogen engine; the condensation and heat dissipation system is responsible for cooling the organic working fluid in the high-temperature organic Rankine cycle system and the low-temperature organic Rankine cycle system and heating the liquid ammonia in the fuel supply circuit.

[0008] Furthermore, the cryogenic organic Rankine cycle system includes a cryogenic working fluid pump, a fuel cell cooler, a heat pump condenser, a cryogenic regenerator, a cylinder liner water cooler, a cryogenic exhaust heat exchanger, a cryogenic expander, a cryogenic condenser, and a cryogenic storage tank. The cryogenic storage tank is used to store the cryogenic organic working fluid. The cryogenic storage tank, cryogenic working fluid pump, cryogenic regenerator, cylinder liner water cooler, cryogenic exhaust heat exchanger, and cryogenic expander are connected in sequence. The cryogenic expander, cryogenic regenerator, cryogenic condenser, and cryogenic storage tank are then connected in sequence to form the cryogenic organic Rankine cycle system. The cryogenic expander is connected to the cryogenic generator of the power generation and energy storage system. The cryogenic organic Rankine cycle system is coupled to the condensation and heat dissipation system through the cryogenic condenser and is connected to the fuel cell. The cooling system is coupled to the fuel cell cooler and to the heat pump system via a heat pump condenser. The high-temperature organic Rankine cycle system includes a high-temperature working fluid pump, a high-temperature regenerator, a high-temperature exhaust heat exchanger, a high-temperature expander, a high-temperature condenser, and a high-temperature storage tank. The high-temperature storage tank stores the high-temperature organic working fluid. The high-temperature storage tank, high-temperature working fluid pump, high-temperature regenerator, high-temperature exhaust heat exchanger, and high-temperature expander are connected in sequence. The high-temperature expander, the high-temperature regenerator, the high-temperature condenser, and the high-temperature storage tank are then connected in sequence to form a high-temperature organic Rankine cycle system loop. The high-temperature expander is connected to the high-temperature generator of the power generation and energy storage system. The high-temperature organic Rankine cycle system is coupled to the condensation and heat dissipation system via the high-temperature condenser.

[0009] Furthermore, the condensation and heat dissipation system includes a coolant pump, a high-temperature stage condenser, a low-temperature stage condenser, a coolant radiator, a primary fan, and a liquid ammonia evaporator. The low-temperature stage condenser, high-temperature stage condenser, coolant pump, coolant radiator, and liquid ammonia evaporator are connected in sequence, and the liquid ammonia evaporator is then connected to the low-temperature stage condenser to form a condensation and heat dissipation circulation system loop. The primary fan is connected to the coolant radiator. The condensation and heat dissipation system is coupled to the high-temperature stage organic Rankine cycle system through the high-temperature stage condenser. The condensation and heat dissipation system is also coupled to the low-temperature stage organic Rankine cycle system through the low-temperature stage condenser.

[0010] Furthermore, the fuel cell cooling system includes a fuel cell radiator, a fuel cell cooler, a fuel cell cooling water pump, a heat pump heat exchanger, a three-way valve (number 3), a three-way valve (number 4), a three-way valve (number 5), and a three-way valve (number 6). The fuel cell outlet is connected to the three-way valve (number 3). One path of the three-way valve (number 3) is connected sequentially to the heat pump heat exchanger and the five-way valve, and then returns to the fuel cell via the fuel cell cooling water pump. The other path of the three-way valve (number 3) is connected to the four-way valve. The two outlets of the four-way valve are connected to the fuel cell radiator and the fuel cell cooler, respectively. The outlets of the fuel cell radiator and the fuel cell cooler converge at the six-way valve. The outlets of the six-way valve and the heat pump heat exchanger are connected to the five-way valve, and finally, the system completes the circulation via the fuel cell cooling water pump, returning to the fuel cell inlet. The fuel cell cooling system is coupled to the low-temperature organic Rankine cycle system through the fuel cell cooler, and the fuel cell cooling system is coupled to the heat pump system through the heat pump heat exchanger.

[0011] Furthermore, the heat pump system includes a compressor, a No. 1 three-way valve, a No. 2 three-way valve, a solenoid valve, a No. 1 electronic expansion valve, a No. 2 electronic expansion valve, a heat pump heat exchanger, an external heat exchanger, and a heat pump condenser; the compressor outlet is connected to the No. 1 three-way valve; one branch of the No. 1 three-way valve is sequentially connected to the solenoid valve, the heat pump heat exchanger, and the No. 2 three-way valve, and finally connected to the compressor inlet; the other branch of the No. 1 three-way valve is sequentially connected to the heat pump condenser, the No. 1 electronic expansion valve, the heat pump heat exchanger, the No. 2 three-way valve, the No. 2 electronic expansion valve, and the external heat exchanger, and finally flows into the compressor inlet; the heat pump system is coupled to the low-temperature organic Rankine cycle system through the heat pump condenser, and the heat pump system is coupled to the fuel cell cooling system through the heat pump heat exchanger.

[0012] Furthermore, the fuel supply circuit includes a liquid ammonia storage tank, a switching valve, a liquid ammonia pump, a No. 3 electronic expansion valve, a liquid ammonia evaporator, a superheater, a No. 7 three-way valve, an ammonia cracking and separation unit, a No. 1 electric heater, and a No. 2 electric heater. The liquid ammonia storage tank, the switching valve, the liquid ammonia pump, the No. 3 electronic expansion valve, the liquid ammonia evaporator, and the superheater are connected in sequence, and then the flow is split through the No. 7 three-way valve. One branch of the No. 7 three-way valve is connected to the ammonia-hydrogen engine, and the other branch of the No. 7 three-way valve is connected in sequence to the ammonia cracking and separation unit, the superheater, and the ammonia-hydrogen engine. The No. 1 electric heater is connected to the ammonia cracking and separation unit, and the No. 2 electric heater is connected to the superheater, thus forming the fuel supply circuit. The fuel supply circuit is coupled to the condensation and heat dissipation system through the liquid ammonia evaporator.

[0013] As a second aspect of the present invention, a control method for a waste heat recovery device in an ammonia-hydrogen engine-fuel cell hybrid system is provided, which is implemented using the waste heat recovery device for an ammonia-hydrogen engine-fuel cell hybrid system described in the present invention, and includes the following steps:

[0014] Obtain the vehicle's required power and the fuel cell stack temperature;

[0015] The operating mode of the power system is determined based on the required power: when the required power is ≤ the first threshold, a pure ammonia-hydrogen engine waste heat recovery mode is adopted; when the required power is ≥ the second threshold, a hybrid drive waste heat recovery mode is adopted; when the required power is between the first threshold and the second threshold, a pure fuel cell waste heat recovery mode is adopted; wherein, the second threshold is greater than the first threshold.

[0016] In the pure ammonia-hydrogen engine waste heat recovery mode, the waste heat of ammonia-hydrogen engine exhaust gas and cylinder liner water is recovered through the high-temperature organic Rankine cycle system and the low-temperature organic Rankine cycle system, while the heat pump system and fuel cell cooling system are shut down.

[0017] In the hybrid drive waste heat recovery mode, if the fuel cell stack temperature is not higher than the target temperature, the heat pump system is started to heat the fuel cell, and the high-temperature organic Rankine cycle system and the low-temperature Rankine cycle system are run to recover the waste heat of the engine and fuel cell; if the fuel cell stack temperature is higher than the target temperature, the heat pump system is turned off, and the low-temperature Rankine cycle is used to directly recover the waste heat of the fuel cell coolant.

[0018] In pure fuel cell waste heat recovery mode, if the fuel cell stack temperature is not higher than the target temperature, the heat pump system is started for heating; if the fuel cell stack temperature is higher than the target temperature and the fuel cell power is not higher than the battery power threshold, the fuel cell cooling system dissipates heat to the environment; if the fuel cell stack temperature is higher than the target temperature and the fuel cell power is higher than the battery power threshold, the heat pump system is started to improve the waste heat quality of the fuel cell and drive the low-temperature Rankine cycle to generate electricity.

[0019] Furthermore, in the waste heat recovery mode of the pure ammonia-hydrogen engine: the fuel supply circuit, the high-temperature organic Rankine cycle system, the low-temperature organic Rankine cycle system, the power generation and energy storage system, and the condensation and heat dissipation system are started and operated; the heat pump system and the fuel cell cooling system are stopped.

[0020] Furthermore, in the hybrid-driven waste heat recovery mode:

[0021] When the operating temperature of the fuel cell stack is less than or equal to the target temperature, the high-temperature organic Rankine cycle system, the low-temperature organic Rankine cycle system, the power generation and energy storage system, the fuel supply loop, and the condensation and heat dissipation system start to operate. The fuel cell cooling system operates in fuel cell-heat pump heat exchange mode; the heat pump system operates in fuel cell heating mode.

[0022] When the operating temperature of the fuel cell stack exceeds the target temperature, the high-temperature organic Rankine cycle system, the low-temperature organic Rankine cycle system, the power generation and energy storage system, the fuel supply loop, and the condensation and heat dissipation system begin to operate. The fuel cell cooling system operates in the fuel cell-low-temperature organic Rankine cycle heat exchange mode; the heat pump system stops operating.

[0023] Furthermore, in the pure fuel cell waste heat recovery mode:

[0024] When the operating temperature of the fuel cell stack is less than or equal to the target temperature, the fuel supply loop, the high-temperature organic Rankine cycle system, the low-temperature organic Rankine cycle system, the power generation and energy storage system, and the condensation and heat dissipation system stop operating; the heat pump system operates in fuel cell heating mode; and the fuel cell cooling system operates in fuel cell-heat pump heat exchange mode.

[0025] When the fuel cell stack operating temperature is greater than the target temperature and the fuel cell power is less than or equal to the battery power threshold, the fuel supply loop, high-temperature organic Rankine cycle system, low-temperature organic Rankine cycle system, power generation and energy storage system, condensation and heat dissipation system, and heat pump system stop operating; the fuel cell cooling system operates in fuel cell-air heat exchange mode.

[0026] When the fuel cell stack operating temperature is greater than the target temperature and the fuel cell power is greater than the battery power threshold, the fuel supply loop and the high-temperature organic Rankine cycle system stop operating; the low-temperature organic Rankine cycle system, the power generation and storage system, and the condensation and heat dissipation system start operating, the heat pump system operates in the low-temperature organic Rankine cycle heating mode, and the fuel cell cooling system operates in the fuel cell-heat pump heat exchange mode.

[0027] Compared with the prior art, the waste heat recovery device and control method for the ammonia-hydrogen engine-fuel cell hybrid system provided by the present invention have the following beneficial effects:

[0028] It achieves efficient energy recovery in a tiered manner, significantly improving the overall vehicle energy efficiency: By constructing a dual organic Rankine cycle with high-temperature and low-temperature stages, it precisely matches and recovers high-grade engine exhaust gas and medium- and low-grade cylinder liner water and fuel cell coolant waste heat, realizing tiered and efficient energy conversion, converting waste heat into electrical energy storage, and directly improving the overall fuel utilization rate of the hybrid system and the energy economy of the vehicle.

[0029] Intelligent multi-mode dynamic switching perfectly suits the complex operating conditions of hybrid vehicles: The proposed control strategy can intelligently determine and switch the system operating mode from pure engine / pure fuel cell / hybrid drive recovery mode based on the vehicle's real-time power demand, fuel cell temperature, and ambient temperature. This ensures that the waste heat recovery system can dynamically adapt to the full operating conditions of hybrid vehicles, achieving an optimal balance between thermal management needs and energy recovery, and improving the system's practicality and overall efficiency.

[0030] An innovative heat pump coupling mechanism overcomes the challenge of low-grade waste heat recovery: A heat pump system is creatively deeply coupled, enabling it to function as a "waste heat grade enhancement device" under specific operating conditions. This design breaks through the technical bottleneck of directly generating electricity from low-grade fuel cell waste heat. By increasing its temperature through heat pump circulation, it can drive a Rankine cycle for power generation, greatly expanding the boundaries and efficiency of waste heat recovery.

[0031] High integration and synergistic optimization achieve system compactness and doubled efficiency: Waste heat from the condensation and cooling system is used to evaporate liquid ammonia in the fuel supply loop, achieving synergy between thermal management and fuel supply, and improving overall system efficiency. Through optimized piping and valve control strategies, key components such as the heat pump condenser and fuel cell cooler are assigned different functions in different modes, greatly improving system integration and component utilization, which helps reduce the difficulty and cost of hybrid vehicle deployment. Attached Figure Description

[0032] Figure 1 This is a schematic diagram illustrating the composition and working principle of the waste heat recovery device of the ammonia-hydrogen engine-fuel cell hybrid system described in Embodiment 1 of the present invention.

[0033] Figure 2 This is an overall flowchart of the control method for the waste heat recovery device of the ammonia-hydrogen engine-fuel cell hybrid system described in Embodiment 2 of the present invention.

[0034] Figure 3 This is a flowchart illustrating the waste heat recovery mode of the ammonia-hydrogen engine in Embodiment 2 of the present invention.

[0035] Figure 4 This is the working circuit of the waste heat recovery device in the waste heat recovery mode of the pure ammonia-hydrogen engine in Embodiment 2 of the present invention.

[0036] Figure 5 This is a flowchart of the hybrid-driven waste heat recovery mode in Embodiment 2 of the present invention.

[0037] Figure 6 This is the working circuit of the waste heat recovery device in the hybrid drive waste heat recovery mode in Embodiment 2 of the present invention.

[0038] Figure 7 This is a flowchart of the pure fuel cell waste heat recovery mode in Embodiment 2 of the present invention.

[0039] Figure 8 This is the working circuit of the waste heat recovery device in the pure fuel cell waste heat recovery mode in Embodiment 2 of the present invention.

[0040] In the picture:

[0041] 1-Ammonia-hydrogen engine; 2-Fuel cell; 3-High-temperature working fluid pump; 4-High-temperature stage regenerator; 5-High-temperature stage exhaust heat exchanger; 6-High-temperature stage expander; 7-High-temperature stage condenser; 8-High-temperature stage liquid storage tank; 9-Low-temperature stage working fluid pump; 10-Fuel cell cooler; 11-Heat pump condenser; 12-Low-temperature stage regenerator; 13-Cylinder liner water cooler; 14-Low-temperature stage exhaust heat exchanger; 15-Low-temperature stage expander; 16-Low-temperature stage condenser; 17-Low-temperature stage liquid storage tank; 18-Coolant working fluid pump; 19-Coolant radiator; 20-Fan 1; 21-Liquid ammonia evaporator; 22-Fuel cell radiator; 23-Fan 2; 24-Fuel cell cooling water pump; 25-Heat pump heat exchanger; 2 6- No. 1 three-way valve; 27- No. 2 three-way valve; 28- No. 3 three-way valve; 29- No. 4 three-way valve; 30- No. 5 three-way valve; 31- No. 6 three-way valve; 32- No. 7 three-way valve; 33- External heat exchanger; 34- Compressor; 35- Solenoid valve; 36- No. 1 electronic expansion valve; 37- No. 2 electronic expansion valve; 38- High-temperature generator; 39- Low-temperature generator; 40- AC-DC converter; 41- DC-DC converter; 42- Power battery; 43- Liquid ammonia storage tank; 44- Switch valve; 45- Liquid ammonia pump; 46- No. 3 electronic expansion valve; 47- Superheater; 48- Ammonia cracking and separation unit; 49- No. 1 electric heater; 50- No. 2 electric heater; 51- Cylinder liner water pump. Detailed Implementation

[0042] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments:

[0043] Example 1:

[0044] This embodiment describes a waste heat recovery device for an ammonia-hydrogen engine-fuel cell hybrid system, such as... Figure 1 As shown.

[0045] The heat sources of the ammonia-hydrogen engine-fuel cell hybrid system mainly include the exhaust gas from the ammonia-hydrogen engine, cylinder liner water, and fuel cell coolant. Based on the heat source temperature, the waste heat sources are categorized into high- and medium-grade ammonia-hydrogen engine exhaust gas, and low-grade cylinder liner water and fuel cell coolant.

[0046] The waste heat recovery system includes a fuel cell, an ammonia-hydrogen engine, a high-temperature organic Rankine cycle system, a low-temperature organic Rankine cycle system, a fuel cell cooling system, a heat pump system, a power generation and energy storage system, a condensation and heat dissipation system, and a fuel supply circuit. The high-temperature organic Rankine cycle system absorbs heat from the exhaust gas of the ammonia-hydrogen engine, while the low-temperature organic Rankine cycle system absorbs heat from the exhaust gas, cylinder liner water, and fuel cell coolant. The power generation and energy storage system converts the heat absorbed by the high-temperature and low-temperature organic Rankine cycles into electrical energy, which is then stored in the power battery. The power battery also provides power to the electric heater in the fuel supply circuit. When the fuel cell is operating, the heat pump system and fuel cell cooling system perform cold start and temperature maintenance. Under specific operating conditions, the heat pump system provides heat to the low-temperature organic Rankine cycle system. When the ammonia-hydrogen engine is operating, the fuel supply circuit provides hydrogen and ammonia for combustion. The condensation and heat dissipation system cools the organic working fluids in both the high-temperature and low-temperature organic Rankine cycles and heats the liquid ammonia in the fuel supply circuit, causing it to evaporate into a gaseous state.

[0047] Specifically, the cryogenic organic Rankine cycle system is used to absorb heat from the cylinder liner water of the cylinder liner water pump 51 of the ammonia-hydrogen engine 1, the engine exhaust gas, and the fuel cell coolant. The cryogenic organic Rankine cycle system includes a cryogenic working fluid pump 9, a fuel cell cooler 10, a heat pump condenser 11, a cryogenic regenerator 12, a cylinder liner water cooler 13, a cryogenic exhaust heat exchanger 14, a cryogenic expander 15, a cryogenic condenser 16, and a cryogenic storage tank 17. The cryogenic storage tank 17 stores the cryogenic organic working fluid. The cryogenic storage tank 17, cryogenic working fluid pump 9, cryogenic regenerator 12, cylinder liner water cooler 13, cryogenic exhaust heat exchanger 14, and cryogenic expander 15 are connected in sequence. The expander 15, the low-temperature stage regenerator 12, the low-temperature stage condenser 16, and the low-temperature stage liquid storage tank 17 are then connected in sequence to form a low-temperature stage organic Rankine cycle system; the low-temperature stage expander 15 is connected to the low-temperature stage generator 39 of the power generation and energy storage system; the low-temperature stage organic Rankine cycle system is coupled to the condensation and heat dissipation system through the low-temperature stage condenser 16; the low-temperature stage organic Rankine cycle system is coupled to the fuel cell cooling system through the fuel cell cooler 10; and the low-temperature stage organic Rankine cycle system is coupled to the heat pump system through the heat pump condenser 11.

[0048] The low-temperature organic Rankine cycle system operates in two modes: start-up mode and start-stop mode. In start-up mode, the low-pressure, low-temperature organic working fluid is pumped out by the low-temperature working fluid pump 9. The high-pressure, low-temperature organic working fluid then enters the fuel cell cooler 10, heat pump condenser 11, low-temperature regenerator 12, cylinder liner water cooler 13, and low-temperature exhaust heat exchanger 14 to absorb heat. At this point, the low-temperature organic working fluid is evaporated into a high-temperature, high-pressure gaseous form, which then enters the low-temperature expander 15 to perform work. The expander drives the connected low-temperature generator 39 to convert thermal energy into electrical energy. The high-temperature, low-pressure exhaust gas then enters the low-temperature regenerator 12 to release some energy, heating the low-temperature organic working fluid. Finally, it enters the low-temperature condenser 16, where it is condensed into a saturated liquid and enters the low-temperature storage tank 17, completing the low-temperature organic Rankine cycle. In start-stop mode, the system stops operating.

[0049] Specifically, the high-temperature organic Rankine cycle system is used to recover heat contained in the exhaust gas of an ammonia-hydrogen engine. The high-temperature organic Rankine cycle system includes a high-temperature working fluid pump 3, a high-temperature regenerator 4, a high-temperature exhaust heat exchanger 5, a high-temperature expander 6, a high-temperature condenser 7, and a high-temperature liquid storage tank 8. The high-temperature liquid storage tank 8 is used to store the high-temperature organic working fluid. The high-temperature working fluid pump 3, the high-temperature regenerator 4, the high-temperature exhaust heat exchanger 5, and the high-temperature expander 6 are connected in sequence. The high-temperature expander 6, the high-temperature regenerator 4, the high-temperature condenser 7, and the high-temperature liquid storage tank 8 are then connected in sequence to form a high-temperature organic Rankine cycle system loop. The high-temperature expander 6 is connected to a high-temperature generator 38 of the power generation and energy storage system. The high-temperature organic Rankine cycle system is coupled to the condensation and heat dissipation system through the high-temperature condenser 7.

[0050] The high-temperature organic Rankine cycle system has two modes: start-up mode and start-stop mode. The start-up mode works as follows: Low-pressure, low-temperature high-temperature organic working fluid is pumped out by the high-temperature working fluid pump 3 and enters the high-temperature regenerator 4. The regenerator 4 absorbs heat from the exhaust gas of the organic working fluid for primary heating. Then, it enters the high-temperature exhaust heat exchanger 5 to absorb some heat from the exhaust gas of the ammonia-hydrogen engine for secondary heating. The high-temperature organic working fluid is evaporated into a high-temperature, high-pressure gaseous form, and then enters the high-temperature expander 6 to perform work. The expander drives the high-temperature generator 38 to convert thermal energy into electrical energy. At this time, the pressure of the organic working fluid decreases. The low-pressure, high-temperature organic working fluid exhaust gas then enters the high-temperature regenerator 4 to release some heat, preheating the organic working fluid from the high-temperature working fluid pump 3. The exhaust gas is then condensed into a saturated liquid by the high-temperature condenser 7 of the condensation and heat dissipation system and finally enters the high-temperature storage tank 8, thus completing the high-temperature organic Rankine cycle. The working principle of the start-stop mode of the high-temperature organic Rankine cycle system is as follows: the high-temperature organic Rankine cycle system stops running.

[0051] Specifically, the condensation and heat dissipation system is used to cool and condense the exhaust gas of the organic working fluid in the high-temperature organic Rankine cycle system and the low-temperature organic Rankine cycle system, and to provide heat for the liquid ammonia in the fuel supply loop to evaporate the liquid ammonia. The condensation and heat dissipation system includes a coolant working fluid pump 18, a high-temperature condenser 7 and a low-temperature condenser 16, a coolant radiator 19, a primary fan 20, and a liquid ammonia evaporator 21. The low-temperature condenser 16, the high-temperature condenser 7, the coolant working fluid pump 18, the coolant radiator 19, and the liquid ammonia evaporator 21 are connected in sequence. The liquid ammonia evaporator 21 is then connected to the low-temperature condenser 16 to form a condensation and heat dissipation cycle system loop. The primary fan 20 is connected to the coolant radiator 19. The condensation and heat dissipation system is coupled to the high-temperature organic Rankine cycle system through the high-temperature condenser 7; the condensation and heat dissipation system is coupled to the low-temperature organic Rankine cycle system through the low-temperature condenser 16.

[0052] The condensation and heat dissipation system has three operating modes: low-temperature condensation and heat dissipation mode, high-temperature condensation and heat dissipation mode, and start-stop mode. The ambient temperature is categorized into low-temperature (-10℃~15℃) and medium-high-temperature (above 15℃). The working principle of the low-temperature condensation and heat dissipation mode is as follows: When the ambient temperature is low (-10℃~15℃) and the condensation and heat dissipation system is operating, the low-temperature condensation and heat dissipation mode is activated. The coolant is pressurized and pumped out from the outlet of the coolant working fluid pump 18, first passing through the coolant radiator 19. At this time, the first fan 20 stops working to reduce heat exchange between the coolant and the outside air. Then, it sequentially passes through the liquid ammonia evaporator 21, the low-temperature stage condenser 16, and the high-temperature stage condenser 7 for heat exchange and cooling, finally returning to the inlet of the coolant working fluid pump 18, thus completing the condensation and heat dissipation cycle. The working principle of the medium-high temperature condensation and heat dissipation mode is as follows: When the ambient temperature is above medium-high (15℃) and the condensation and heat dissipation system is working, the high-temperature condensation and heat dissipation mode is activated. The coolant is pressurized and pumped out from the outlet of the coolant working fluid pump 18, first passing through the coolant radiator 19. At this time, the first fan 20 is working to increase the heat exchange between the coolant and the outside air. Then, it passes through the liquid ammonia evaporator 21, the low-temperature stage condenser 16, and the high-temperature stage condenser 7 in sequence for heat exchange and cooling, and finally returns to the inlet of the coolant working fluid pump 18, thus completing the condensation and heat dissipation cycle. The working principle of the condensation and heat dissipation system start-stop mode is as follows: the condensation and heat dissipation system stops working.

[0053] Specifically, the power generation and energy storage system includes a high-temperature generator 38, a low-temperature generator 39, an AC-DC converter 40, a DC-DC converter 41, and a power battery 42. The high-temperature generator 38 is connected to the high-temperature expander 6 of the high-temperature organic Rankine cycle system, and the low-temperature generator 39 is connected to the low-temperature expander 15 of the low-temperature organic Rankine cycle system. Both the high-temperature generator 38 and the low-temperature generator 39 are connected to the AC-DC converter 40. The AC-DC converter 40, the DC-DC converter 41, and the power battery 42 are connected in sequence. The power battery 42 is electrically connected to the first electric heater 49 and the second electric heater 50 in the fuel supply circuit, respectively.

[0054] The power generation and energy storage system operates in two modes: start-up mode and start-stop mode. In start-up mode, the system generates alternating current (AC) by being driven by either the high-temperature generator 38 or the low-temperature generator 39, which in turn is powered by either the high-temperature expander 6 or the low-temperature expander 15. This AC power is then rectified into direct current (DC) by the AC-DC converter 40. The DC power is then precisely regulated in terms of voltage and current by the DC-DC converter 41 before being charged into the power battery 42. The power battery 42 provides power to the first electric heater 49 and the second electric heater 50 in the fuel supply circuit. In start-stop mode, the system stops operating.

[0055] Specifically, the fuel cell cooling system is used for cold start and temperature maintenance of the fuel cell. The fuel cell cooling system includes a fuel cell radiator 22, a second fan 23, a fuel cell cooler 10, a fuel cell cooling water pump 24, a heat pump heat exchanger 25, a three-way valve 28, a four-way valve 29, a five-way valve 30, and a six-way valve 31. The outlet of fuel cell 2 is connected to the three-way valve 28. One path of the three-way valve 28 is connected sequentially to the heat pump heat exchanger 25 and the five-way valve 30, then returns to fuel cell 2 via the fuel cell cooling water pump 24. The other path of the three-way valve 28 is connected to the four-way valve 29. 9 can be connected to either fuel cell radiator 22 or fuel cell cooler 10. The outlets of fuel cell radiator 22 and fuel cell cooler 10 are both connected to three-way valve 31. Three-way valve 31 and the outlet of heat pump heat exchanger 25 are connected to three-way valve 30. Finally, the cooling water is circulated through fuel cell cooling water pump 24 and returns to the inlet of fuel cell 2. The fuel cell cooling system is coupled to the low-temperature organic Rankine cycle system through fuel cell cooler 10. The fuel cell cooling system is coupled to the heat pump system through heat pump heat exchanger 25.

[0056] The fuel cell cooling system operates in four modes: fuel cell-air heat exchange mode, fuel cell-heat pump heat exchange mode, fuel cell-low-temperature organic Rankine cycle heat exchange mode, and start-stop mode. The working principle of the fuel cell-heat pump heat exchange mode is as follows: By adjusting three-way valves 28 (number 3), 29 (number 4), 30 (number 5), and 31 (number 6), the flow direction of the fuel cell coolant is adjusted, closing the branch flowing into the fuel cell cooler 10 and the fuel cell radiator 22. This allows the fuel cell coolant to flow into the branch of the heat pump heat exchanger 25. The high-temperature fuel cell coolant in the loop is pressurized by the fuel cell cooling water pump 24 and enters the fuel cell system to release heat, heating the fuel cell stack and lowering the coolant temperature. Then, the low-temperature fuel cell coolant passes through three-way valves 28 and 29 to absorb heat from the refrigerant in the heat pump system, raising the coolant temperature. Finally, the coolant passes through three-way valve 30 to enter the fuel cell cooling water pump 24, completing the fuel cell cooling cycle. The working principle of the fuel cell-air heat exchange mode is as follows: By adjusting the flow direction of the fuel cell coolant through three-way valves 28, 29, 30, and 31, the branch flowing into the fuel cell cooler 10 and the heat pump heat exchanger 25 is closed, allowing the fuel cell coolant to flow into the fuel cell radiator 22. The low-temperature fuel cell coolant in the loop is pressurized by the fuel cell cooling water pump 24 and flows through the fuel cell system, absorbing heat from the fuel cell stack, thus increasing the temperature of the fuel cell coolant. Then, the high-temperature fuel cell coolant enters the fuel cell radiator 22 through three-way valves 28 and 29 to adjust its flow direction, releasing heat and decreasing the temperature of the fuel cell coolant. Subsequently, the low-temperature fuel cell coolant passes through three-way valves 31 and 30 in sequence, and finally flows back into the fuel cell cooling water pump 24, completing the fuel cell cooling cycle. The working principle of the fuel cell-low-temperature organic Rankine cycle heat exchange mode is as follows: By adjusting the flow direction of the fuel cell coolant through three-way valves 28, 29, 30, and 31, the branch flowing into the heat pump heat exchanger 25 and the fuel cell radiator 22 is closed, allowing the fuel cell coolant to flow into the fuel cell cooler 10. The low-temperature fuel cell coolant in the loop is pressurized by the fuel cell cooling water pump 24 and enters the fuel cell system, absorbing heat from the fuel cell stack, thus raising the temperature of the fuel cell coolant. Then, the high-temperature fuel cell coolant passes through three-way valves 28 and 29 to adjust its flow direction before entering the fuel cell cooler 10 to release heat, heating the low-temperature organic working fluid in the low-temperature organic Rankine cycle, thus lowering the temperature of the fuel cell coolant. Subsequently, the low-temperature fuel cell coolant passes through three-way valves 31 and 30 to adjust its flow direction before entering the fuel cell cooling water pump 24, completing the fuel cell cooling cycle.The start-stop mode of the fuel cell cooling system works by stopping the fuel cell cooling system.

[0057] Specifically, the heat pump system is used to perform cold start and temperature maintenance of the fuel cell. The heat pump system includes a compressor 34, a first three-way valve 26, a second three-way valve 27, a solenoid valve 35, a first electronic expansion valve 36, a second electronic expansion valve 37, a heat pump heat exchanger 25, an external heat exchanger 33, and a heat pump condenser 11. The heat pump system is coupled to the low-temperature organic Rankine cycle system through the heat pump condenser 11, and the heat pump system is coupled to the fuel cell cooling system through the heat pump heat exchanger 25. The outlet of the compressor 34 is connected to the first three-way valve 26. One branch of the first three-way valve 26 is connected in sequence to the solenoid valve 35, the heat pump heat exchanger 25, the second three-way valve 27, and finally to the inlet of the compressor 34. The other branch of the first three-way valve 26 is connected in sequence to the heat pump condenser 11, the first electronic expansion valve 36, the heat pump heat exchanger 25, the second three-way valve 27, the second electronic expansion valve 37, the external heat exchanger 33, and finally flows into the inlet of the compressor 34.

[0058] The heat pump system operates in three modes: fuel cell heating mode, low-temperature organic Rankine cycle heating mode, and start-stop mode. The working principle of the fuel cell heating mode is as follows: In the fuel cell heating mode circuit, the low-temperature, low-pressure gaseous refrigerant first passes through compressor 34, where it is compressed into a high-temperature, high-pressure gas. Then, the refrigerant flows through a three-way valve 26 to a solenoid valve 35, where its flow rate is regulated. It then enters the heat pump heat exchanger 25 to release heat, heating the fuel cell coolant. At this time, the refrigerant condenses from a high-temperature, high-pressure gaseous state to a low-temperature, high-pressure liquid state. The low-temperature, high-pressure refrigerant then flows through a three-way valve 27 to a two-way electronic expansion valve 37, where its pressure is reduced to a low-temperature, low-pressure liquid fluid. Finally, the low-temperature, low-pressure refrigerant enters the external heat exchanger 33 to absorb external heat, evaporates into a gaseous state, and finally flows into compressor 34, completing the heat pump cycle. The working principle of the low-temperature organic Rankine cycle heat exchange mode is as follows: The low-temperature, low-pressure gaseous refrigerant in the circuit first passes through the compressor 34, where it is compressed into a high-temperature, high-pressure gas. Then, after the refrigerant's flow direction is regulated by the No. 1 three-way valve 26, it enters the heat pump heat exchanger 25 to release heat, heating the low-temperature organic working fluid. At this time, the high-temperature, high-pressure gaseous refrigerant condenses into a low-temperature, high-pressure liquid form. Then, the low-temperature, high-pressure liquid refrigerant passes through the No. 1 electronic expansion valve 36 for throttling and pressure reduction, becoming a low-temperature, low-pressure liquid refrigerant. The refrigerant then enters the heat pump heat exchanger 25, absorbs heat from the fuel cell coolant, and is evaporated into a gaseous form. After its flow direction is regulated by the No. 2 three-way valve 27, it flows into the compressor 34, completing the heat pump cycle. The working principle of the heat pump system start-stop mode is as follows: The heat pump system stops working.

[0059] Specifically, the fuel supply circuit is used to provide the ammonia and hydrogen required for combustion in the ammonia-hydrogen engine 1. The fuel supply circuit includes a liquid ammonia storage tank 43, a switching valve 44, a liquid ammonia pump 45, a No. 3 electronic expansion valve 46, a liquid ammonia evaporator 21, a superheater 47, a No. 7 three-way valve 32, an ammonia cracking and separation unit 48, a No. 1 electric heater 49, and a No. 2 electric heater 50; the fuel supply circuit is coupled to the condensation and heat dissipation system through the liquid ammonia evaporator 21. The liquid ammonia storage tank 43, the switch valve 44, the liquid ammonia pump 45, the No. 3 electronic expansion valve 46, the liquid ammonia evaporator 21, and the superheater 47 are connected in sequence. Then, the flow is split through the No. 7 three-way valve 32. One branch of the No. 7 three-way valve 32 is connected to the ammonia-hydrogen engine 1, and the other branch of the No. 7 three-way valve 32 is connected in sequence to the ammonia cracking and separation unit 48 and the superheater 47. Finally, it is connected to the ammonia-hydrogen engine 1. The No. 1 electric heater 49 is connected to the ammonia cracking and separation unit 48, and the No. 2 electric heater 50 is connected to the superheater 47, forming a fuel supply circuit.

[0060] The fuel supply circuit has two modes: start-up mode and start-stop mode. The start-up mode works as follows: Switch valve 44 opens, and liquid ammonia is pumped out under pressure by liquid ammonia pump 45. After entering electronic expansion valve 46, the flow rate of liquid ammonia is dynamically adjusted according to system requirements. Then, it enters liquid ammonia evaporator 21, absorbing heat from the condensation and heat dissipation circuit. The liquid ammonia is evaporated into ammonia gas, which then enters superheater 47. Through electric heater 50 and the residual heat from hydrogen generated after ammonia cracking, the ammonia fuel from liquid ammonia evaporator 21 is further heated, resulting in a certain degree of superheat at the outlet of superheater 47. This ensures that the ammonia fuel at the outlet of superheater 47 is in a superheated gaseous state, preventing liquid slugging during subsequent ammonia fuel supply and ammonia cracking processes. Then, the ammonia gas is split via three-way valve 32 (number 7). One stream enters the ammonia-hydrogen engine 1 for combustion and power generation, while the other stream enters the ammonia cracking and separation unit 48 and is heated by electric heater 49 (number 1) to decompose into hydrogen. The hydrogen then releases some heat after passing through heater 47, superheating the ammonia gas before finally entering the ammonia-hydrogen engine 1 for combustion and power generation. The fuel supply circuit start-stop mode operates as follows: the fuel supply circuit stops operating.

[0061] Example 2:

[0062] This embodiment describes a control method for a waste heat recovery device in an ammonia-hydrogen engine-fuel cell hybrid system, which is implemented using the waste heat recovery device for an ammonia-hydrogen engine-fuel cell hybrid system described in Embodiment 1; as follows Figure 2 As shown, it includes the following steps:

[0063] Acquire signals for vehicle power demand, fuel cell stack temperature, and ambient temperature.

[0064] The operating mode of the power system is determined based on the required power: when the required power... ≤ First threshold At that time, a pure ammonia-hydrogen engine waste heat recovery mode is adopted; when the required power ≥ second threshold (Second threshold) Greater than the first threshold When the power demand is high, a hybrid drive waste heat recovery mode is adopted; when the power demand is high... Between the first threshold With the second threshold During this period, a pure fuel cell waste heat recovery mode is adopted;

[0065] In the pure ammonia-hydrogen engine waste heat recovery mode, the waste heat of ammonia-hydrogen engine exhaust gas and cylinder liner water is recovered through the high-temperature organic Rankine cycle system and the low-temperature organic Rankine cycle system, while the heat pump system and fuel cell cooling system are shut down.

[0066] In the hybrid drive waste heat recovery mode, if the fuel cell stack temperature is not higher than the target temperature, the heat pump system is started to heat the fuel cell, and the high-temperature organic Rankine cycle system and the low-temperature Rankine cycle system are run to recover the waste heat of the engine and fuel cell; if the fuel cell stack temperature is higher than the target temperature, the heat pump system is turned off, and the low-temperature Rankine cycle is used to directly recover the waste heat of the fuel cell coolant.

[0067] In pure fuel cell waste heat recovery mode, if the fuel cell stack temperature is not higher than the target temperature, the heat pump system is started for heating; if the fuel cell stack temperature is higher than the target temperature and the fuel cell power is not higher than the battery power threshold, the fuel cell cooling system dissipates heat to the environment; if the fuel cell stack temperature is higher than the target temperature and the fuel cell power is higher than the battery power threshold, the heat pump system is started to improve the waste heat quality of the fuel cell and drive the low-temperature Rankine cycle to generate electricity.

[0068] Specifically, such as Figure 3 , Figure 4 As shown, the specific control strategy for the waste heat recovery mode of the pure ammonia-hydrogen engine is as follows:

[0069] When power demand ≤ first threshold At this time, the power system adopts the pure ammonia-hydrogen engine mode. The ammonia-hydrogen engine is working, the fuel cell is not working, and the heat source is the exhaust gas of the ammonia-hydrogen engine and the cylinder liner water. The waste heat recovery system adopts the pure ammonia-hydrogen engine waste heat recovery mode.

[0070] When the external environment t is low (-10℃≤t≤15℃), the fuel supply circuit, high-temperature organic Rankine cycle system, low-temperature organic Rankine cycle system, and power generation and energy storage system operate in start-up mode, the heat pump system and fuel cell cooling system operate in start-stop mode, and the condensation and heat dissipation system operates in low-temperature condensation and heat dissipation mode.

[0071] When the external environment temperature t is medium to high (t > 15℃), the fuel supply circuit, high-temperature organic Rankine cycle system, low-temperature organic Rankine cycle system, and power generation and energy storage system operate in start-up mode; the heat pump system and fuel cell cooling system operate in start-stop mode; and the condensation and heat dissipation system operates in high-temperature condensation and heat dissipation mode.

[0072] The fuel supply circuit provides hydrogen and ammonia to the ammonia-hydrogen engine by absorbing heat from the coolant in the condensation and heat dissipation system to evaporate ammonia and by using electrical energy from the power battery to crack hydrogen from ammonia. The high-temperature organic Rankine cycle system and the low-temperature organic Rankine cycle system recover residual heat from the exhaust gas and cylinder liner water of the ammonia-hydrogen engine through organic working fluids and convert it into electrical energy. The alternating current is converted into direct current through the power generation and energy storage system and stored in the power battery. The condensation and heat dissipation system absorbs heat from the exhaust gas of the organic working fluid in the high-temperature organic Rankine cycle system and the low-temperature organic Rankine cycle system to condense it and heats the liquid ammonia in the fuel supply circuit to evaporate it.

[0073] Specifically, such as Figure 5 , Figure 6 As shown, the specific control strategy of the hybrid-driven waste heat recovery mode is as follows:

[0074] When power demand ≥ the second threshold At this time, the power system adopts a hybrid mode, in which the ammonia-hydrogen engine and the fuel cell work simultaneously. The heat sources include the exhaust gas of the ammonia-hydrogen engine, cylinder liner water and fuel cell coolant. The waste heat recovery system adopts a hybrid drive waste heat recovery mode.

[0075] In the hybrid-driven waste heat recovery mode, when the fuel cell stack operating temperature T ≤ target temperature T1 and the external environment t is low (-10℃ ≤ t ≤ 15℃), the high-temperature organic Rankine cycle system, the low-temperature organic Rankine cycle system, the power generation and energy storage system, and the fuel supply circuit start up in the start-up mode; the heat pump system operates in the fuel cell heating mode; the fuel cell cooling system operates in the fuel cell-heat pump heat exchange mode; and the condensation heat dissipation system operates in the low-temperature condensation heat dissipation mode.

[0076] In the hybrid-driven waste heat recovery mode, when the fuel cell stack operating temperature T ≤ target temperature T1 and the external environment t is at a medium to high temperature (t > 15℃), the high-temperature organic Rankine cycle system, the low-temperature organic Rankine cycle system, the power generation and energy storage system, and the fuel supply circuit start operating in the start-up mode; the heat pump system operates in the fuel cell heating mode; the fuel cell cooling system operates in the fuel cell-heat pump heat exchange mode; and the condensation heat dissipation system operates in the high-temperature condensation heat dissipation mode.

[0077] In the hybrid-driven waste heat recovery mode, when the fuel cell stack operating temperature T > target temperature T1 and the external environment t is low (-10℃≤t≤15℃), the high-temperature organic Rankine cycle system, the low-temperature organic Rankine cycle system, the power generation and energy storage system, and the fuel supply circuit start up in the start-up mode; the heat pump system operates in the start-stop mode; the fuel cell cooling system operates in the fuel cell-low-temperature organic Rankine cycle heat exchange mode; and the condensation heat dissipation system operates in the low-temperature condensation heat dissipation mode.

[0078] In the hybrid-driven waste heat recovery mode, when the fuel cell stack operating temperature T > target temperature T1 and the external environment t is at a medium to high temperature (t > 15℃), the high-temperature organic Rankine cycle system, the low-temperature organic Rankine cycle system, the power generation and energy storage system, and the fuel supply circuit start up in the start-up mode; the heat pump system operates in the start-stop mode; the fuel cell cooling system operates in the fuel cell-low-temperature organic Rankine cycle heat exchange mode; and the condensation heat dissipation system operates in the high-temperature condensation heat dissipation mode.

[0079] The fuel supply circuit provides hydrogen and ammonia to the ammonia-hydrogen engine by absorbing heat from the coolant in the condensation and heat dissipation system to evaporate ammonia and by using electrical energy from the power battery to crack hydrogen from ammonia. The heat pump system and the condensation and heat dissipation system are responsible for the cold start and temperature maintenance of the fuel cell. The high-temperature organic Rankine cycle system and the low-temperature organic Rankine cycle system recover residual heat from the exhaust gas of the ammonia-hydrogen engine, cylinder liner water, and fuel cell coolant through organic working fluid, and convert it into electrical energy. The alternating current is converted into direct current through the power generation and energy storage system and stored in the power battery. The condensation and heat dissipation system absorbs heat from the exhaust gas of the organic working fluid in the high-temperature organic Rankine cycle system and the low-temperature organic Rankine cycle system to condense it, and heats the liquid ammonia in the fuel supply circuit to evaporate it.

[0080] Specifically, such as Figure 7 , Figure 8 As shown, the specific control strategy for the pure fuel cell waste heat recovery mode is as follows:

[0081] When power demand At the first threshold Second threshold During this period, a pure fuel cell mode is used, in which only the fuel cell works, the ammonia-hydrogen engine stops working, and the only waste heat source is the fuel cell coolant. The waste heat recovery system adopts a pure fuel cell waste heat recovery mode.

[0082] When the fuel cell stack operating temperature T ≤ target temperature T1, the fuel supply loop, high-temperature organic Rankine cycle system, low-temperature organic Rankine cycle system, power generation and energy storage system, and condensation and heat dissipation system operate in start-stop mode; the heat pump system operates in fuel cell heating mode; and the fuel cell cooling system operates in fuel cell-heat pump heat exchange mode. At this time, the heat pump system and fuel cell cooling system are responsible for the cold start of the fuel cell.

[0083] When the fuel cell stack operating temperature T > the target temperature T1 and the fuel cell power ≤ Battery power threshold The fuel supply loop, high-temperature organic Rankine cycle system, low-temperature organic Rankine cycle system, power generation and energy storage system, condensation and heat dissipation system, and heat pump system operate in start-stop mode; the fuel cell cooling system operates in fuel cell-air heat exchange mode. At this time, the fuel cell cooling system is responsible for maintaining the temperature of the fuel cell.

[0084] When the fuel cell stack operating temperature T > the target temperature T1 and the fuel cell power >Battery power threshold At this time, the fuel supply loop and the high-temperature organic Rankine cycle system operate in start-stop mode; the low-temperature organic Rankine cycle system and the power generation and energy storage system operate in start-up mode; the heat pump system operates in low-temperature organic Rankine cycle heating mode; the fuel cell cooling system operates in fuel cell-heat pump heat exchange mode; and the condensation and heat dissipation system operates in high-temperature condensation and heat dissipation mode. In this mode, the heat pump system provides a heat source for the low-temperature organic Rankine cycle system, the condensation and heat dissipation system is responsible for maintaining the temperature of the fuel cell, the low-temperature organic Rankine cycle system recovers residual heat from the organic working fluid fuel cell coolant and converts it into electrical energy, which is then converted from AC to DC by the power generation and energy storage system and stored in the power battery, and the condensation and heat dissipation system absorbs heat from the exhaust gas of the organic working fluid in the low-temperature organic Rankine cycle system, causing it to condense.

Claims

1. A waste heat recovery device for an ammonia-hydrogen engine-fuel cell hybrid system, characterized in that, The system includes a fuel cell, an ammonia-hydrogen engine, a high-temperature organic Rankine cycle system, a low-temperature organic Rankine cycle system, a fuel cell cooling system, a heat pump system, a power generation and energy storage system, a condensation and heat dissipation system, and a fuel supply circuit. The high-temperature organic Rankine cycle system absorbs heat from the exhaust gas of the ammonia-hydrogen engine, while the low-temperature organic Rankine cycle system absorbs heat from the exhaust gas of the ammonia-hydrogen engine, cylinder liner water, and fuel cell coolant. The power generation and energy storage system converts the heat energy absorbed by the high-temperature and low-temperature organic Rankine cycles into electrical energy and stores it in the power battery, which also provides power to the electric heater in the fuel supply circuit. The heat pump system has a fuel cell heating mode and a low-temperature organic Rankine cycle heating mode. The fuel cell cooling system has a fuel cell-air heat exchange mode, a fuel cell-heat pump heat exchange mode, and a fuel cell-low-temperature organic Rankine cycle heat exchange mode. When the ammonia-hydrogen engine is working, the fuel supply circuit is responsible for providing hydrogen and ammonia for combustion. The condensation and heat dissipation system is responsible for cooling the organic working fluids in the high-temperature and low-temperature organic Rankine cycles and heating the liquid ammonia in the fuel supply circuit.

2. The waste heat recovery device for an ammonia-hydrogen engine-fuel cell hybrid system as described in claim 1, characterized in that, The cryogenic organic Rankine cycle system includes a cryogenic working fluid pump (9), a fuel cell cooler (10), a heat pump condenser (11), a cryogenic regenerator (12), a cylinder liner water cooler (13), a cryogenic exhaust heat exchanger (14), a cryogenic expander (15), a cryogenic condenser (16), and a cryogenic storage tank (17); the cryogenic storage tank (17) is used to store the cryogenic organic working fluid. The cylinder liner water cooler (13), the low-temperature exhaust heat exchanger (14), and the low-temperature expander (15) are connected in sequence. The low-temperature expander (15), the low-temperature regenerator (12), the low-temperature condenser (16), and the low-temperature liquid storage tank (17) are then connected in sequence to form a low-temperature organic Rankine cycle system. The low-temperature expander (15) is connected to the low-temperature generator (39) of the power generation and energy storage system. The low-temperature organic Rankine cycle system and the condensation and heat dissipation system are coupled through the low-temperature condenser (16). The system is coupled to the fuel cell cooling system via the fuel cell cooler (10) and to the heat pump system via the heat pump condenser (11). The high-temperature organic Rankine cycle system includes a high-temperature working fluid pump (3), a high-temperature regenerator (4), a high-temperature exhaust heat exchanger (5), a high-temperature expander (6), a high-temperature condenser (7), and a high-temperature liquid storage tank (8). The high-temperature liquid storage tank (8) is used to store the high-temperature organic working fluid. The high-temperature liquid storage tank (8), the high-temperature working fluid pump (3), the high-temperature regenerator (4), the high-temperature exhaust heat exchanger (5), and the high-temperature expander (6) are connected in sequence. The high-temperature expander (6), the high-temperature regenerator (4), the high-temperature condenser (7), and the high-temperature liquid storage tank (8) are then connected in sequence to form a high-temperature organic Rankine cycle system loop. The high-temperature expander (6) is connected to the high-temperature generator (38) of the power generation and energy storage system. The high-temperature organic Rankine cycle system is coupled to the condensation and heat dissipation system via the high-temperature condenser (7).

3. The waste heat recovery device for an ammonia-hydrogen engine-fuel cell hybrid system as described in claim 1, characterized in that, The condensation and heat dissipation system includes a coolant working fluid pump (18), a high-temperature stage condenser (7), a low-temperature stage condenser (16), a coolant radiator (19), a first fan (20), and a liquid ammonia evaporator (21). The low-temperature stage condenser (16), the high-temperature stage condenser (7), the coolant working fluid pump (18), the coolant radiator (19), and the liquid ammonia evaporator (21) are connected in sequence. The liquid ammonia evaporator (21) is then connected to the low-temperature stage condenser (16) to form a condensation and heat dissipation circulation system loop. The first fan (20) is connected to the coolant radiator (19). The condensation and heat dissipation system is coupled to the high-temperature stage organic Rankine cycle system through the high-temperature stage condenser (7). The condensation and heat dissipation system is coupled to the low-temperature stage organic Rankine cycle system through the low-temperature stage condenser (16).

4. The waste heat recovery device for an ammonia-hydrogen engine-fuel cell hybrid system as described in claim 1, characterized in that, The fuel cell cooling system includes a fuel cell radiator (22), a fuel cell cooler (10), a fuel cell cooling water pump (24), a heat pump heat exchanger (25), a three-way valve (28), a three-way valve (29), a three-way valve (30), and a three-way valve (31); the outlet of the fuel cell (2) is connected to the three-way valve (28); one path of the three-way valve (28) is connected to the heat pump heat exchanger (25) and the three-way valve (30) in sequence, and then returns to the fuel cell (2) via the fuel cell cooling water pump (24); the other path of the three-way valve (28) is connected to the three-way valve (29), and the three-way valve (21)... (29) The two outlets are connected to the fuel cell radiator (22) and the fuel cell cooler (10) respectively. The outlets of the fuel cell radiator (22) and the fuel cell cooler (10) are all connected to the No. 6 three-way valve (31). The outlet of the No. 6 three-way valve (31) and the heat pump heat exchanger (25) are connected to the No. 5 three-way valve (30). Finally, the circulation is completed by the fuel cell cooling water pump (24) and returned to the inlet of the fuel cell (2). The fuel cell cooling system is coupled to the low-temperature organic Rankine cycle system through the fuel cell cooler (10), and the fuel cell cooling system is coupled to the heat pump system through the heat pump heat exchanger (25).

5. The waste heat recovery device for an ammonia-hydrogen engine-fuel cell hybrid system as described in claim 1, characterized in that, The heat pump system includes a compressor (34), a first three-way valve (26), a second three-way valve (27), a solenoid valve (35), a first electronic expansion valve (36), a second electronic expansion valve (37), a heat pump heat exchanger (25), an external heat exchanger (33), and a heat pump condenser (11); the outlet of the compressor (34) is connected to the first three-way valve (26); one branch of the first three-way valve (26) is connected in sequence to the solenoid valve (35), the heat pump heat exchanger (25), the second three-way valve (27), and finally to... The compressor (34) inlet is connected; the other branch of the first three-way valve (26) is connected in sequence to the heat pump condenser (11), the first electronic expansion valve (36), the heat pump heat exchanger (25), the second three-way valve (27), the second electronic expansion valve (37), the external heat exchanger (33), and finally flows into the compressor (34) inlet; the heat pump system is coupled to the low-temperature organic Rankine cycle system through the heat pump condenser (11), and the heat pump system is coupled to the fuel cell cooling system through the heat pump heat exchanger (25).

6. The waste heat recovery device for an ammonia-hydrogen engine-fuel cell hybrid system as described in claim 1, characterized in that, The fuel supply circuit includes a liquid ammonia storage tank (43), a switching valve (44), a liquid ammonia pump (45), a No. 3 electronic expansion valve (46), a liquid ammonia evaporator (21), a superheater (47), a No. 7 three-way valve (32), an ammonia cracking and separation unit (48), a No. 1 electric heater (49), and a No. 2 electric heater (50); the liquid ammonia storage tank (43), the switching valve (44), the liquid ammonia pump (45), the No. 3 electronic expansion valve (46), the liquid ammonia evaporator (21), and the superheater (47) are connected in sequence. Then, the fuel is diverted through the No. 7 three-way valve (32). One branch of the No. 7 three-way valve (32) is connected to the ammonia-hydrogen engine (1), and the other branch of the No. 7 three-way valve (32) is connected in sequence to the ammonia cracking and separation unit (48), the superheater (47), and the ammonia-hydrogen engine (1). The No. 1 electric heater (49) is connected to the ammonia cracking and separation unit (48), and the No. 2 electric heater (50) is connected to the superheater (47), forming a fuel supply circuit. The fuel supply circuit is coupled to the condensation and heat dissipation system through the liquid ammonia evaporator (21).

7. A control method for a waste heat recovery device in an ammonia-hydrogen engine-fuel cell hybrid system, which is implemented using the waste heat recovery device for an ammonia-hydrogen engine-fuel cell hybrid system as described in claim 1, characterized in that... Includes the following steps: Obtain the vehicle's required power and the fuel cell stack temperature; The operating mode of the power system is determined based on the required power: when the required power is ≤ the first threshold, the pure ammonia-hydrogen engine waste heat recovery mode is adopted; when the required power is ≥ the second threshold, the hybrid drive waste heat recovery mode is adopted. When the power demand is between the first threshold and the second threshold, a pure fuel cell waste heat recovery mode is adopted; wherein, the second threshold is greater than the first threshold. In the pure ammonia-hydrogen engine waste heat recovery mode, the waste heat of ammonia-hydrogen engine exhaust gas and cylinder liner water is recovered through the high-temperature organic Rankine cycle system and the low-temperature organic Rankine cycle system, while the heat pump system and fuel cell cooling system are shut down. In the hybrid drive waste heat recovery mode, if the fuel cell stack temperature is not higher than the target temperature, the heat pump system is started to heat the fuel cell, and the high-temperature organic Rankine cycle system and the low-temperature Rankine cycle system are run to recover the waste heat of the engine and fuel cell; if the fuel cell stack temperature is higher than the target temperature, the heat pump system is turned off, and the low-temperature Rankine cycle is used to directly recover the waste heat of the fuel cell coolant. In pure fuel cell waste heat recovery mode, if the fuel cell stack temperature is not higher than the target temperature, the heat pump system is started for heating; if the fuel cell stack temperature is higher than the target temperature and the fuel cell power is not higher than the battery power threshold, the fuel cell cooling system dissipates heat to the environment; if the fuel cell stack temperature is higher than the target temperature and the fuel cell power is higher than the battery power threshold, the heat pump system is started to improve the waste heat quality of the fuel cell and drive the low-temperature Rankine cycle to generate electricity.

8. The control method for a waste heat recovery device in an ammonia-hydrogen engine-fuel cell hybrid system as described in claim 7, characterized in that, In the waste heat recovery mode of the pure ammonia-hydrogen engine: the fuel supply circuit, high-temperature organic Rankine cycle system, low-temperature organic Rankine cycle system, power generation and energy storage system, and condensation and heat dissipation system are started and operated; the heat pump system and fuel cell cooling system are stopped.

9. The control method for a waste heat recovery device in an ammonia-hydrogen engine-fuel cell hybrid system as described in claim 7, characterized in that, In the hybrid-driven waste heat recovery mode: When the operating temperature of the fuel cell stack is less than or equal to the target temperature, the high-temperature organic Rankine cycle system, the low-temperature organic Rankine cycle system, the power generation and energy storage system, the fuel supply loop, and the condensation and heat dissipation system start to operate. The fuel cell cooling system operates in fuel cell-heat pump heat exchange mode; the heat pump system operates in fuel cell heating mode. When the operating temperature of the fuel cell stack exceeds the target temperature, the high-temperature organic Rankine cycle system, the low-temperature organic Rankine cycle system, the power generation and energy storage system, the fuel supply loop, and the condensation and heat dissipation system begin to operate. The fuel cell cooling system operates in the fuel cell-low-temperature organic Rankine cycle heat exchange mode; the heat pump system stops operating.

10. The control method for a waste heat recovery device in an ammonia-hydrogen engine-fuel cell hybrid system as described in claim 7, characterized in that, In the pure fuel cell waste heat recovery mode: When the operating temperature of the fuel cell stack is less than or equal to the target temperature, the fuel supply loop, the high-temperature organic Rankine cycle system, the low-temperature organic Rankine cycle system, the power generation and energy storage system, and the condensation and heat dissipation system stop operating; the heat pump system operates in fuel cell heating mode; and the fuel cell cooling system operates in fuel cell-heat pump heat exchange mode. When the fuel cell stack operating temperature is greater than the target temperature and the fuel cell power is less than or equal to the battery power threshold, the fuel supply loop, high-temperature organic Rankine cycle system, low-temperature organic Rankine cycle system, power generation and energy storage system, condensation and heat dissipation system, and heat pump system stop operating; the fuel cell cooling system operates in fuel cell-air heat exchange mode. When the fuel cell stack operating temperature is greater than the target temperature and the fuel cell power is greater than the battery power threshold, the fuel supply loop and the high-temperature organic Rankine cycle system stop operating; the low-temperature organic Rankine cycle system, the power generation and storage system, and the condensation and heat dissipation system start operating, the heat pump system operates in the low-temperature organic Rankine cycle heating mode, and the fuel cell cooling system operates in the fuel cell-heat pump heat exchange mode.

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