Ammonia fuel solid oxide fuel cell cooling, heating, electricity and water multi-combined supply system and method

Abstract

The invention relates to the technical field of new energy and distributed power generation, in particular to an ammonia fuel solid oxide fuel cell cooling, heating, electricity and water multi-combined supply system and method. Comprising an ammonia gas cracking and purifying unit, a thermoelectric power generation unit, a solid oxide fuel cell, a heat pump cycle, an organic Rankine cycle unit, a sewage purification unit and a tower type solar photo-thermal unit, the system produces hydrogen through ammonia cracking, and the hydrogen is purified and then supplied to an SOFC for power generation. Multi-generation of cold, heat, electricity and water can be achieved, the problems of energy gradient utilization and heat management among units of the system are effectively solved, and the special requirements of the distributed power generation system are met.

Description

Technical Field

[0001] This invention relates to the fields of new energy and distributed power generation technology, and in particular to a combined cooling, heating, power and water system and method for ammonia fuel solid oxide fuel cell. Background Technology

[0002] As the global energy structure accelerates its transformation towards green and low-carbon energy, regional distributed generation systems urgently require clean, efficient, and diversified energy supply solutions. Ammonia, especially "green ammonia" produced from renewable energy sources, is considered a highly promising zero-carbon energy carrier due to its suitable energy density, relatively mild storage and transportation conditions, and near-zero carbon emissions throughout its entire life cycle. However, directly burning ammonia in internal combustion engines presents challenges such as slow combustion speed, high ignition energy, and the easy generation of nitrogen oxides, limiting its direct application in distributed generation systems. Solid oxide fuel cell technology provides an ideal pathway for ammonia energy utilization: its high-temperature operating environment perfectly meets the requirements for ammonia cracking to produce hydrogen, and its energy conversion efficiency is significantly higher than that of traditional heat engines.

[0003] In existing technologies, the overall energy utilization efficiency of SOFC-based distributed systems is generally low. While some SOFC-ORC systems achieve combined cooling, heating, and power (CCHP), their overall system efficiency is only around 58%, and they exhibit significant shortcomings in thermal management, failing to effectively address the cascade utilization of high-temperature exhaust energy. For typical distributed energy users, their energy demands are usually diversified, requiring the simultaneous fulfillment of multiple end-user needs such as stable power supply, space cooling / heating, domestic hot water, and high-quality fresh water. Existing system architectures struggle to organically integrate and efficiently coordinate these heterogeneous energy demands, limiting their overall energy efficiency and economic benefits. Summary of the Invention

[0004] The purpose of this invention is to provide a combined cooling, heating, electricity and water supply system and method for ammonia fuel solid oxide fuel cells, which aims to solve the problems of low overall energy utilization efficiency of existing systems, inability to achieve combined cooling, heating, electricity and water supply, and the existence of energy cascade utilization and thermal management problems between system units.

[0005] To achieve the above objectives, the present invention employs an ammonia-fueled solid oxide fuel cell combined cooling, heating, power, and water system, comprising a liquid ammonia evaporator, an ammonia cracking and purification unit, a hydrogen buffer tank, a solid oxide fuel cell, a tower-type solar thermal unit, a wastewater purification unit, an alkali metal thermoelectric converter unit, an organic Rankine cycle unit, a heat pump cycle, and a nitrogen storage tank; wherein; The nitrogen storage tank is used to store nitrogen. The liquid ammonia evaporator is used to provide a cooling effect; The ammonia cracking and purification unit is used to convert liquid ammonia into hydrogen. The hydrogen buffer tank is used to buffer the hydrogen produced by cracking, so that the hydrogen can enter the solid oxide fuel cell stably. The solid oxide fuel cell is used to generate electricity by electrochemically reacting hydrogen with oxygen in the air. The thermoelectric power generation unit is used to recover waste heat from the fuel cell cathode exhaust gas using an alkali metal thermoelectric converter to generate electricity. The heat pump cycle is used to provide cooling and heating based on a vapor compression cycle; The organic Rankine cycle unit is used to generate electricity by recovering low-temperature waste heat from the system using a dual-loop structure. The wastewater purification unit is used to produce fresh water using multi-stage flash evaporation technology and waste heat discharged from the cooling circuit of the solid oxide fuel cell stack. The power management and control module is used to coordinate the operation of each unit and to optimize energy allocation. The tower-type solar thermal unit is used to provide auxiliary heating for anode recirculation gas and process water using a tower-type heat collection system.

[0006] The ammonia cracking and purification unit includes an ammonia cracker and a hydrogen purification device; wherein: The ammonia cracker is used to crack gaseous ammonia into a hydrogen-nitrogen mixture using the system's waste heat. The hydrogen purification device is used to separate high-purity hydrogen from a mixed gas using a nickel-based hydrogen separation membrane.

[0007] The thermoelectric power generation unit uses an alkali metal thermoelectric converter. The hot end inlet of the alkali metal thermoelectric converter is directly connected to the cathode exhaust port of the fuel cell, and the cold end inlet is connected to the ambient air. The thermal energy is directly converted into electrical energy through the electrochemical cycle of sodium ions. The converted medium-temperature exhaust gas continues to provide the heat required to maintain the temperature of the ammonia cracker.

[0008] The heat pump cycle uses R123 as the working fluid and includes a compressor, condenser, expansion valve, and evaporator; wherein: The heat pump cycle uses R123 as the working fluid and includes a compressor, condenser, expansion valve, and evaporator; wherein: The compressor is used to couple with the liquid ammonia storage tank to perform vaporization refrigeration of liquid ammonia; The condenser is used to connect to the heating network to provide hot water and steam; The expansion valve is used to reduce the pressure of the refrigerant to achieve low-temperature vaporization. The evaporator is used to recover waste heat from the system to vaporize the organic working fluid.

[0009] The organic Rankine cycle unit adopts a dual-loop structure. The primary loop recovers the medium-temperature waste heat from the outlet of the thermoelectric power generation unit, and the secondary loop recovers other low-temperature waste heat in the system. The two loops are thermally coupled through an intermediate heat exchanger.

[0010] The wastewater purification unit employs a four-stage flash evaporation structure, including a preheater, multi-stage flash chambers, a vacuum system, and a freshwater collection system; wherein: The preheater is used to utilize the fuel cell stack cooling water as a heat source; The multi-stage flash chamber is used to achieve low-temperature boiling of wastewater by gradually reducing the pressure. The freshwater collection system is used to collect freshwater; The vacuum system is used to reduce the pressure in the purification tank to achieve efficient flash evaporation.

[0011] This invention also provides a method for combined cooling, heating, power and water supply in an ammonia-fueled solid oxide fuel cell, comprising the following steps: Liquid ammonia is vaporized in an evaporator to absorb heat from the environment, providing cooling, and is converted into gaseous ammonia. Gaseous ammonia is decomposed into a hydrogen-nitrogen mixture in a pyrolyzer using the system's waste heat. The mixture is then separated into high-purity hydrogen through a nickel-based hydrogen separation membrane. The hydrogen and air react to generate electricity in the solid oxide fuel cell, and some of the anode exhaust gas is cooled, separated, and then reheated by solar energy and returned to the anode inlet. Thermoelectric conversion is performed, with the cathode exhaust driving the alkali metal thermoelectric converter to generate electricity, and the outlet gas continuing to supply heat to the ammonia cracker; Utilizing waste heat in a cascade manner, the system uses low-temperature waste heat to drive a dual-loop organic Rankine cycle for power generation, and uses fuel cell stack cooling water to drive a multi-stage flash evaporation wastewater purification device to produce fresh water. It provides both heating and cooling; the heat pump cycle provides cooling through the vaporization of liquid ammonia and heating through the condensation process. Based on real-time operating data, a multi-objective optimization algorithm is used to dynamically adjust key parameters such as liquid ammonia flow rate, air flow rate, and fuel cell temperature to optimize the overall system performance.

[0012] This invention discloses a combined cooling, heating, power, and water system and method for an ammonia-fueled solid oxide fuel cell. The system includes a nitrogen storage tank for storing nitrogen, a liquid ammonia evaporator for providing cooling, an ammonia cracking and purification unit for converting liquid ammonia into hydrogen, a thermoelectric power generation unit that uses an alkali metal thermoelectric converter to recover waste heat from the fuel cell cathode exhaust for power generation, a solid oxide fuel cell for generating electricity through an electrochemical reaction between hydrogen and oxygen in the air, a heat pump cycle for providing cooling and heating based on a vapor compression cycle, an organic Rankine cycle unit for generating electricity by recovering low-temperature waste heat from the system using a dual-loop structure, a wastewater purification unit using multi-stage flash evaporation technology to produce fresh water from the fuel cell stack cooling circuit, and a power management and control module for coordinating the operation of each unit and optimizing energy allocation. A tower-type solar thermal unit uses a tower-type heat collection system to provide auxiliary heating for the anode recirculation gas and process water. The system employs the following steps: vaporizing liquid ammonia in an evaporator to absorb ambient heat for cooling and converting it into gaseous ammonia; converting the gaseous ammonia into gaseous ammonia; and converting the liquid ammonia into gaseous ammonia. In the pyrolysis unit, ammonia is decomposed into a hydrogen-nitrogen mixture using waste heat. This mixture is then separated into high-purity hydrogen via a nickel-based hydrogen separation membrane. Hydrogen is then used for power generation, reacting with air in a solid oxide fuel cell. Part of the anode exhaust gas is cooled, separated, and then reheated by solar energy before returning to the anode inlet. Thermoelectric conversion occurs, with cathode exhaust driving an alkali metal thermoelectric converter to generate electricity, and the outlet gas continuing to heat the ammonia pyrolysis unit. Waste heat is utilized in a cascade manner, with low-temperature waste heat driving a dual-loop organic Rankine cycle for power generation, and fuel cell stack cooling water driving a multi-stage flash evaporation wastewater purification unit to produce fresh water. Heating and cooling are also provided, with a heat pump cycle providing cooling through liquid ammonia vaporization and heating through condensation. Based on real-time operating data, a multi-objective optimization algorithm dynamically adjusts key parameters such as liquid ammonia flow rate, air flow rate, and fuel cell temperature to optimize overall system performance. Through these methods, a high energy efficiency is achieved, enabling combined cooling, heating, electricity, and water supply. This effectively solves the problems of energy cascade utilization and thermal management between system units, meeting the specific needs of distributed power generation systems. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the combined cooling, heating, power and water supply system for ammonia fuel solid oxide fuel cells according to the present invention.

[0015] Figure 2This is a schematic diagram of the principle of the ammonia cracking and purification unit of the present invention.

[0016] Figure 3 This is a schematic diagram illustrating the principle of the heat pump cycle of the present invention.

[0017] Figure 4 This is a schematic diagram of the wastewater purification unit of the present invention.

[0018] Figure 5 This is a flowchart of the steps of the combined cooling, heating, power and water supply method for ammonia fuel solid oxide fuel cells of the present invention.

[0019] 1-Liquid ammonia evaporator, 2-Ammonia cracking and purification unit, 3-Hydrogen buffer tank, 4-Solid oxide fuel cell, 5-Tower solar thermal unit, 6-Wastewater purification unit, 7-Thermoelectric power generation unit, 8-Organic Rankine cycle unit, 9-Heat pump cycle, 10-Nitrogen storage tank, 21-Ammonia cracker, 22-Hydrogen purification device, 61-Preheater, 62-Multi-stage flash chamber, 63-Vacuum system, 64-Fresh water collection system, 91-Compressor, 92-Condenser, 93-Expansion valve, 94-Evaporator. Detailed Implementation

[0020] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application.

[0021] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0022] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0023] Please see Figures 1-4This invention provides a combined cooling, heating, power and water system for an ammonia-fueled solid oxide fuel cell 4, comprising a liquid ammonia evaporator 1, an ammonia cracking and purification unit 2, a hydrogen buffer tank 3, a solid oxide fuel cell 4, a tower-type solar thermal unit 5, a wastewater purification unit 6, an alkali metal thermoelectric converter unit, an organic Rankine cycle unit 8, a heat pump cycle 9, and a nitrogen storage tank 10; wherein; The nitrogen storage tank 10 is used to store nitrogen. The liquid ammonia evaporator 1 is used to provide a cooling effect; The ammonia cracking and purification unit 2 is used to convert liquid ammonia into hydrogen. The hydrogen buffer tank 3 is used to buffer the hydrogen produced by cracking, so that the hydrogen can enter the solid oxide fuel cell 4 stably. The solid oxide fuel cell 4 is used to generate electricity by electrochemically reacting hydrogen with oxygen in the air. The thermoelectric power generation unit 7 is used to recover waste heat from the fuel cell cathode exhaust gas using an alkali metal thermoelectric converter to generate electricity. The heat pump cycle 9 is used to provide cooling and heating based on a vapor compression cycle; The organic Rankine cycle unit 8 is used to generate electricity by recovering low-temperature waste heat from the system using a dual-loop structure. The wastewater purification unit 6 is used to produce fresh water using the waste heat discharged from the cooling circuit of the solid oxide fuel cell stack 4 using multi-stage flash evaporation technology, and the power management and control module is used to coordinate the operation of each unit and perform optimal energy allocation. The tower-type solar thermal unit 5 is used to provide auxiliary heating for anode recirculation gas and process water using a tower-type heat collection system.

[0024] In this embodiment, the nitrogen storage tank 10 stores nitrogen; the liquid ammonia evaporator 1 provides a cooling effect; the ammonia cracking and purification unit 2 converts liquid ammonia into hydrogen; the hydrogen buffer tank 3 buffers the hydrogen produced by cracking, allowing the hydrogen to stably enter the solid oxide fuel cell 4; the solid oxide fuel cell 4 generates electricity by electrochemically reacting the hydrogen with oxygen in the air; the thermoelectric power generation unit 7 uses an alkali metal thermoelectric converter to recover waste heat from the fuel cell cathode exhaust for power generation; the heat pump cycle 9 provides cooling and heating based on a vapor compression cycle; the organic Rankine cycle unit 8 uses a dual-loop structure to recover low-temperature waste heat in the system for power generation; the wastewater purification unit 6 uses multi-stage flash evaporation technology to produce fresh water using waste heat discharged from the solid oxide fuel cell 4 stack cooling circuit; and the power management and control module coordinates the operation of each unit and performs optimal energy allocation; the tower solar thermal unit 5 uses a tower heat collection system to provide auxiliary heating for the anode recirculation gas and process water. The nickel-based hydrogen separation membrane in the ammonia cracking and purification unit 2 operates at a temperature above 500°C, utilizing the hydrogen partial pressure difference to achieve selective hydrogen permeation. The hydrogen purity on the permeation side reaches over 99.5%, while the nitrogen-rich gas on the non-permeation side is collected as a byproduct. The anode tail gas recirculation system of the solid oxide fuel cell 4 includes a gas-liquid separator, a gas cooler, and a solar reheater. The gas-liquid separator condenses and separates water vapor in the anode outlet gas. The remaining hydrogen is heated to a set temperature by the solar reheater and then returned to the anode inlet. The separated liquid water is heated by solar energy and mixed with the cathode outlet gas to maintain the temperature of the ammonia cracker 21. Through the above methods, a high energy utilization efficiency is achieved, enabling combined cooling, heating, electricity, and water supply, effectively solving the problems of energy cascade utilization and thermal management among various units of the system, and meeting the special needs of distributed generation systems.

[0025] Furthermore, the ammonia cracking and purification unit 2 includes an ammonia cracker 21 and a hydrogen purification device 22; wherein: The ammonia cracker 21 is used to crack gaseous ammonia into a hydrogen-nitrogen mixture using the system's waste heat. The hydrogen purification device 22 is used to separate high-purity hydrogen from the mixed gas using a nickel-based hydrogen separation membrane.

[0026] In this embodiment, the ammonia cracker 21 uses the system waste heat to crack gaseous ammonia into a hydrogen-nitrogen mixture; the hydrogen purification device 22 uses a nickel-based hydrogen separation membrane to separate high-purity hydrogen from the mixture.

[0027] Furthermore, the thermoelectric power generation unit 7 adopts an alkali metal thermoelectric converter. The hot end inlet of the alkali metal thermoelectric converter is directly connected to the cathode exhaust port of the fuel cell, and the cold end inlet is connected to the ambient air. The thermal energy is directly converted into electrical energy through the electrochemical cycle of sodium ions. The converted medium-temperature exhaust gas continues to provide the heat required to maintain the temperature of the ammonia cracker 21.

[0028] Furthermore, the heat pump cycle 9 uses R123 as the working fluid and includes a compressor 91, a condenser 92, an expansion valve 93, and an evaporator 94; wherein: The compressor 91 is used to couple with the liquid ammonia storage tank to perform vaporization refrigeration of liquid ammonia; The condenser 92 is used to connect to the heating network to provide hot water and steam; The expansion valve 93 is used to reduce the pressure of the refrigerant to achieve low-temperature vaporization. The evaporator 94 is used to recover waste heat from the system to vaporize the organic working fluid.

[0029] In this embodiment, the compressor 91 is coupled to the liquid ammonia storage tank to perform vaporization refrigeration of liquid ammonia; the condenser 92 is connected to the heating network to provide hot water and steam; the expansion valve 93 reduces the pressure of the refrigerant to achieve low-temperature vaporization; and the evaporator 94 recovers the system waste heat to achieve vaporization of organic refrigerants.

[0030] Furthermore, the organic Rankine cycle unit 8 adopts a dual-loop structure. The primary loop recovers the medium-temperature waste heat from the outlet of the thermoelectric power generation unit 7, and the secondary loop recovers other low-temperature waste heat in the system. The two loops are thermally coupled through an intermediate heat exchanger and are each equipped with an independent turbine generator set and working fluid pump.

[0031] Furthermore, the wastewater purification unit 6 adopts a four-stage flash evaporation structure, including a preheater 61, a multi-stage flash chamber 62, a vacuum system 63, and a freshwater collection system 64; wherein: The preheater 61 is used to utilize the fuel cell stack cooling water as a heat source. The multi-stage flash chamber 62 is used to achieve low-temperature boiling of wastewater by gradually reducing the pressure. The freshwater collection system 64 is used to collect freshwater; The vacuum system 63 is used to reduce the pressure in the purification tank to achieve efficient flash evaporation.

[0032] In this embodiment, the preheater 61 uses fuel cell stack cooling water as a heat source; the multi-stage flash chamber 62 achieves low-temperature boiling of wastewater by progressively reducing pressure; the freshwater collection system 64 collects freshwater; and the vacuum system 63 reduces the pressure of the purification tank to achieve efficient flash evaporation.

[0033] Furthermore, the tower-type solar thermal unit 5 employs a tower-type heat collection system to provide auxiliary heating for the anode recirculation gas and process water, as well as a power management and control module to coordinate the operation of each unit and achieve optimal energy allocation. The power management and control module includes a data acquisition unit, an optimization calculation unit, and an execution control unit. The data acquisition unit monitors the temperature, pressure, and flow parameters of each node in the system in real time. The optimization calculation unit uses a multi-objective genetic algorithm to calculate the overall system energy efficiency and levelized power cost as optimization objectives. The execution control unit adjusts the operating parameters of key equipment based on the optimization results. Please see Figure 5 This invention provides a method for combined cooling, heating, power, and water supply in an ammonia-fueled solid oxide fuel cell, comprising the following steps: S100: Liquid ammonia is vaporized in a liquid ammonia evaporator to absorb ambient heat, providing cooling, and is converted into gaseous ammonia; S200: Gaseous ammonia is decomposed into a hydrogen-nitrogen mixture in the pyrolyzer using the system's waste heat. The mixture is then separated into high-purity hydrogen by a nickel-based hydrogen separation membrane. S300: Generates electricity by reacting hydrogen and air in a solid oxide fuel cell to generate electricity. Part of the anode exhaust gas is cooled, separated, and then reheated by solar energy and returned to the anode inlet. S400: Performs thermoelectric conversion, cathode exhaust drives alkali metal thermoelectric converter to generate electricity, and the outlet gas continues to supply heat to the ammonia cracker; S500: Utilizing waste heat in a cascaded manner, the low-temperature waste heat in the system drives a dual-loop organic Rankine cycle to generate electricity, and uses the fuel cell stack cooling water to drive a multi-stage flash evaporation wastewater purification device to produce fresh water. S600: Provides heating and cooling. The heat pump cycle provides cooling through liquid ammonia vaporization and heating through condensation. S700: Based on real-time operating data, it uses a multi-objective optimization algorithm to dynamically adjust key parameters such as liquid ammonia flow rate, air flow rate, and fuel cell temperature, so as to optimize the overall performance of the system.

[0034] In this embodiment, liquid ammonia is vaporized in a liquid ammonia evaporator to absorb ambient heat, providing cooling, and is converted into gaseous ammonia. The gaseous ammonia is then decomposed into a hydrogen-nitrogen mixture in a pyrolysis unit using waste heat. This mixture is then separated into high-purity hydrogen via a nickel-based hydrogen separation membrane. Hydrogen is used for power generation; it reacts with air in a solid oxide fuel cell to generate electricity. Part of the anode exhaust gas is cooled, separated, and then reheated by solar energy before being returned to the anode inlet. Thermoelectric conversion occurs; cathode exhaust gas drives an alkali metal thermoelectric converter to generate electricity, and the outlet gas continues to heat the ammonia pyrolysis unit. Utilizing waste heat cascades, the low-temperature waste heat in the system drives a dual-loop organic Rankine cycle. The system generates electricity and uses the cooling water from the fuel cell stack to drive a multi-stage flash evaporation wastewater purification unit to produce fresh water. It also provides heating and cooling, with a heat pump cycle providing cooling through liquid ammonia vaporization and heating through condensation. Based on real-time operating data, a multi-objective optimization algorithm is used to dynamically adjust key parameters such as liquid ammonia flow rate, air flow rate, and fuel cell temperature to optimize the overall system performance. Through the above process, a high energy utilization efficiency is achieved, enabling combined cooling, heating, electricity, and water supply. This effectively solves the problems of energy cascade utilization and thermal management between various units of the system, thus meeting the special needs of distributed power generation systems. Working principle: System Startup and Initialization: Before system startup, a comprehensive inspection and preparation are required. First, check the liquid ammonia storage tank level to ensure sufficient liquid ammonia is present. Check the sealing of all pipeline connections and confirm that all valves are in the correct open / closed positions. Perform a power-on self-test on the control system, checking the operating status of all sensors and actuators. During system startup, the tower-type solar thermal unit is activated first, and the heliostat field automatically tracks the sun's position, reflecting sunlight to the central receiver. The heat transfer medium inside the receiver gradually heats up to the predetermined operating temperature. Simultaneously, the heat pump circulation is started, and the compressor begins operation, providing initial cooling capacity to the system. During startup, the control system will gradually increase the temperature of each unit according to the preset temperature rise curve, avoiding damage to the equipment from sudden temperature changes.

[0035] Liquid ammonia evaporation and refrigeration process: Liquid ammonia is pumped from the storage tank into the liquid ammonia evaporator. The evaporator employs a high-efficiency plate-fin heat exchanger design, featuring a large heat exchange area and excellent heat transfer performance. The liquid ammonia evaporates within the evaporator, absorbing ambient heat to provide cooling for the user. The evaporation pressure is precisely controlled by a back pressure valve to ensure stable evaporation temperature. A temperature sensor at the evaporator outlet monitors the temperature of the gaseous ammonia in real time, maintaining a stable evaporation rate by adjusting the liquid inlet flow rate. The evaporator's cooling capacity can be adjusted according to the user's actual needs to meet cooling requirements under different operating conditions.

[0036] Ammonia Cracking and Hydrogen Purification: Gaseous ammonia enters the ammonia cracking and purification unit through insulated pipelines. This unit mainly consists of two parts: a cracker and a membrane separation unit. The cracker adopts a fixed-bed reactor design, filled with a nickel-based catalyst. The cracker operating temperature is controlled within a suitable reaction temperature range, and the pressure is maintained at the system operating pressure. The cracking reaction is endothermic, and the required heat is provided by the high-temperature waste gas from the system through the shell side. The reaction temperature is controlled by adjusting the waste gas flow rate. The main components of the cracked gas are hydrogen and nitrogen. The hydrogen-nitrogen mixture produced by cracking enters the membrane separation unit. This unit uses multi-stage nickel-based composite membrane separation technology, and the membrane module operating temperature is maintained at a suitable operating temperature. The membrane separation system consists of multiple separation stages, each equipped with a pressure regulation and temperature control system. Driven by the pressure difference, hydrogen selectively permeates through the membrane layer. After multi-stage separation, high-purity hydrogen is obtained. During the separation process, the hydrogen purity is monitored in real time by an online analyzer, and the operating parameters of each stage are automatically adjusted based on the monitoring results. The separated nitrogen-rich gas enters a nitrogen storage tank, which is equipped with an automatic pressure regulation system to store nitrogen at the required pressure for use in inert gas protection systems or other process requirements.

[0037] The high-purity hydrogen for fuel cell power generation first enters a hydrogen buffer tank. The buffer tank's volume is designed according to the system's processing capacity and is equipped with an internal airflow distribution device to ensure stable airflow. The buffer tank's operating pressure is maintained within the system's operating pressure range and is equipped with a safety valve and pressure alarm device. Subsequently, the hydrogen is mixed with recycled anode tail gas, heated to a suitable temperature by a preheater, and then enters the anode of the fuel cell. The fuel cell uses high-temperature solid oxide fuel cell technology, with each cell consisting of an anode, electrolyte, and cathode. The stack consists of multiple cells connected in series, each with a specific effective area. The stack's operating temperature is controlled within a suitable operating temperature range, maintained by adjusting air and fuel flow rates. Air is pressurized by a compressor before entering the cathode, with the air-fuel ratio controlled within a suitable range. In the electrochemical reaction, hydrogen is oxidized at the anode, and oxygen is reduced at the cathode, with the circuit completed through ion conduction in the electrolyte layer. The total power output of the stack is determined according to the system's design capacity, exhibiting high power generation efficiency. To maintain stable stack performance, the system is equipped with an online monitoring device to monitor the stack's operating status in real time.

[0038] Waste heat utilization: The high-temperature exhaust gas generated by the fuel cell first enters the alkali metal thermoelectric converter unit. This unit uses a thermoelectric conversion device to directly generate electricity from the heat of the high-temperature exhaust gas. The thermoelectric conversion device consists of multiple single cells operating within a suitable temperature range. Under optimal operating conditions, the thermoelectric conversion device can convert a portion of the thermal energy into electrical energy. The hot and cold end temperatures of the device are controlled by adjusting the flow rate of the cooling medium to ensure power generation efficiency. Subsequently, the cooled exhaust gas enters the organic Rankine cycle unit. This unit adopts a dual-loop design, using different organic working fluids. The primary loop uses a suitable medium-temperature working fluid to recover medium-temperature waste heat; the secondary loop uses a suitable low-temperature working fluid to further recover low-temperature waste heat. The two loops are thermally coupled through an intermediate heat exchanger and each is equipped with an independent turbine generator set and working fluid pump. The organic working fluid absorbs heat and vaporizes in the evaporator, driving the turbine to generate electricity, and then condenses into a liquid in the condenser, completing the energy conversion cycle. The system's operating parameters are optimized and adjusted by an automatic control system.

[0039] Wastewater purification process: The low-temperature exhaust gas from multi-stage power generation enters the wastewater purification unit. This unit employs a multi-stage flash evaporation design, including a preheater, multiple flash chambers, a vacuum system, and a freshwater collection system. Wastewater first exchanges heat with the exhaust gas in the preheater, reaching a predetermined temperature before entering the flash chambers. Controlled by the vacuum system, each flash chamber is maintained under different pressure conditions, resulting in different evaporation temperatures. The generated steam is condensed to obtain freshwater, while concentrated brine is progressively concentrated before discharge. The system's freshwater production is controlled by adjusting the feed wastewater flow rate and operating parameters.

[0040] Heat pump cycle: The heat pump cycle uses a suitable organic working fluid as the circulation medium and includes four main components: compressor, condenser, expansion valve, and evaporator. The evaporator is coupled to a liquid ammonia evaporator to provide auxiliary cooling capacity. The condenser is connected to the heating system to provide hot water to users. The coefficient of performance (COP) for cooling and heating during system operation is ensured by optimizing operating parameters. The compressor speed can be adjusted according to load demand to achieve energy-saving operation.

[0041] Solar Auxiliary System: The tower-type solar thermal unit includes a heliostat field and a central receiver. The heliostats employ a dual-axis tracking system to precisely track the sun's position and reflect sunlight to the central receiver. The heat transfer medium within the receiver is heated to its operating temperature, providing heat to the anode exhaust gas recirculation system via a heat exchanger. The solar system can also provide auxiliary heat for other processes, reducing the system's dependence on ammonia fuel. The system is equipped with an automatic cleaning device to periodically clean the mirrors and maintain high reflection efficiency.

[0042] Safety Protection System: The system is equipped with multiple safety protection measures: pressure vessels are equipped with safety valves and rupture discs; high-temperature equipment has temperature alarms and interlock shutdown mechanisms; the hydrogen system is equipped with leak detection and automatic shut-off; the electrical system has overload protection and grounding protection. All safety systems comply with the requirements of distributed generation system specifications and undergo regular safety testing and drills.

[0043] Operation and Maintenance: Daily system operation requires recording key process parameters, including ammonia consumption, power generation, and water production. Regular maintenance includes checking catalyst activity, cleaning heat exchangers, and replacing membrane modules. Standard operating procedures are established for all maintenance work to ensure quality. The system is also equipped with a fault diagnosis system to provide early warnings of equipment anomalies and prevent sudden failures.

[0044] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein.

[0045] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope.

Claims

1. A combined cooling, heating, power, and water supply system for an ammonia-fueled solid oxide fuel cell, characterized in that, It includes a liquid ammonia evaporator, an ammonia cracking and purification unit, a hydrogen buffer tank, a solid oxide fuel cell, a tower-type solar thermal unit, a wastewater purification unit, an alkali metal thermoelectric converter unit, an organic Rankine cycle unit, a heat pump cycle, and a nitrogen storage tank. in; The nitrogen storage tank is used to store nitrogen. The liquid ammonia evaporator is used to provide a cooling effect; The ammonia cracking and purification unit is used to convert liquid ammonia into hydrogen. The hydrogen buffer tank is used to buffer the hydrogen produced by cracking, so that the hydrogen can enter the solid oxide fuel cell stably. The solid oxide fuel cell is used to generate electricity by electrochemically reacting hydrogen with oxygen in the air. The thermoelectric power generation unit is used to recover waste heat from the fuel cell cathode exhaust gas using an alkali metal thermoelectric converter to generate electricity. The heat pump cycle is used to provide cooling and heating based on a vapor compression cycle; The organic Rankine cycle unit is used to generate electricity by recovering low-temperature waste heat from the system using a dual-loop structure. The wastewater purification unit is used to produce fresh water using multi-stage flash evaporation technology and waste heat discharged from the cooling circuit of the solid oxide fuel cell stack. The power management and control module is used to coordinate the operation of each unit and to optimize energy allocation. The tower-type solar thermal unit is used to provide auxiliary heating for anode recirculation gas and process water using a tower-type heat collection system.

2. The combined cooling, heating, power, and water supply system for ammonia fuel solid oxide fuel cells as described in claim 1, characterized in that, The ammonia cracking and purification unit includes an ammonia cracker and a hydrogen purification device; wherein: The ammonia cracker is used to crack gaseous ammonia into a hydrogen-nitrogen mixture using the system's waste heat. The hydrogen purification device is used to separate high-purity hydrogen from a mixed gas using a nickel-based hydrogen separation membrane.

3. The combined cooling, heating, power, and water supply system for ammonia fuel solid oxide fuel cells as described in claim 1, characterized in that, The thermoelectric power generation unit uses an alkali metal thermoelectric converter. The hot end inlet of the alkali metal thermoelectric converter is directly connected to the cathode exhaust port of the fuel cell, and the cold end inlet is connected to the ambient air. The thermal energy is directly converted into electrical energy through the electrochemical cycle of sodium ions. The converted medium-temperature exhaust gas continues to provide the heat required to maintain the temperature of the ammonia cracker.

4. The combined cooling, heating, power, and water supply system for ammonia fuel solid oxide fuel cells as described in claim 1, characterized in that, It can generate electricity efficiently while also providing cooling, heating, and freshwater production.

5. The heat pump cycle uses R123 as the working fluid and includes a compressor, condenser, expansion valve, and evaporator; wherein: The compressor is used to couple with the liquid ammonia storage tank to perform vaporization refrigeration of liquid ammonia; The condenser is used to connect to the heating network to provide hot water and steam; The expansion valve is used to reduce the pressure of the refrigerant to achieve low-temperature vaporization. The evaporator is used to recover waste heat from the system to vaporize the organic working fluid.

6. The combined cooling, heating, power, and water supply system for ammonia fuel solid oxide fuel cells as described in claim 1, characterized in that, The organic Rankine cycle unit adopts a dual-loop structure. The primary loop recovers the medium-temperature waste heat from the outlet of the thermoelectric power generation unit, and the secondary loop recovers other low-temperature waste heat in the system. The two loops are thermally coupled through an intermediate heat exchanger.

7. The combined cooling, heating, power, and water supply system for ammonia fuel solid oxide fuel cells as described in claim 1, characterized in that, The wastewater purification unit adopts a four-stage flash evaporation structure, including a preheater, multi-stage flash chambers, a vacuum system, and a freshwater collection system; wherein: The preheater is used to utilize the fuel cell stack cooling water as a heat source; The multi-stage flash chamber is used to achieve low-temperature boiling of wastewater by gradually reducing the pressure. The freshwater collection system is used to collect freshwater; The vacuum system is used to reduce the pressure in the purification tank to achieve efficient flash evaporation.

8. A method for combined cooling, heating, power, and water supply in an ammonia-fueled solid oxide fuel cell, applied to the combined cooling, heating, power, and water supply system of an ammonia-fueled solid oxide fuel cell as described in claim 1, characterized in that, Includes the following steps: Liquid ammonia is vaporized in an evaporator to absorb heat from the environment, providing cooling, and is converted into gaseous ammonia. Gaseous ammonia is decomposed into a hydrogen-nitrogen mixture in a pyrolyzer using the system's waste heat. The mixture is then separated into high-purity hydrogen through a nickel-based hydrogen separation membrane. The hydrogen and air react to generate electricity in the solid oxide fuel cell, and some of the anode exhaust gas is cooled, separated, and then reheated by solar energy and returned to the anode inlet. Thermoelectric conversion is performed, with the cathode exhaust driving the alkali metal thermoelectric converter to generate electricity, and the outlet gas continuing to supply heat to the ammonia cracker; Utilizing waste heat in a cascade manner, the system uses low-temperature waste heat to drive a dual-loop organic Rankine cycle for power generation, and uses fuel cell stack cooling water to drive a multi-stage flash evaporation wastewater purification device to produce fresh water. It provides both heating and cooling; the heat pump cycle provides cooling through the vaporization of liquid ammonia and heating through the condensation process. Based on real-time operating data, a multi-objective optimization algorithm is used to dynamically adjust key parameters such as liquid ammonia flow rate, air flow rate, and fuel cell temperature to optimize the overall system performance.

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