A sealed environment fuel cell cooling and thermoelectric power generation system and method

Abstract

This invention discloses a closed-environment fuel cell cooling and thermoelectric power generation system and method. The system includes a fuel cell stack, a liquid oxygen cooling heat exchanger, a thermoelectric generator array, a fuel cell stack circulating water tank, and a cooling circulation control and heat dissipation component. The cooling circulating water outlet of the fuel cell stack is connected to the cooling circulation control and heat dissipation component, which automatically switches the cooling flow path and dissipates heat according to the circulating water temperature. Both of its outlets are connected to the fuel cell stack circulating water tank, adapting to high and low power operation of the fuel cell stack. The liquid oxygen cooling heat exchanger delivers low-temperature circulating water to the fuel cell stack circulating water tank. The high-temperature surface of the thermoelectric generator array is in contact with the fuel cell stack circulating water tank, and the low-temperature surface is in contact with the liquid oxygen cooling heat exchanger to form thermoelectric power generation, realizing the resource utilization of waste heat and cold. The fuel cell stack circulating water tank is connected to the fuel cell stack and the liquid oxygen cooling heat exchanger after a circulating water pump. This invention can improve system efficiency and thermal efficiency, reduce auxiliary equipment power consumption, and significantly improve the sea passage safety and endurance of a closed underwater transport platform.

Description

Technical Field

[0001] This invention relates to the field of closed-environment energy and power technology, specifically to a closed-environment fuel cell cooling and thermoelectric power generation system and method. Background Technology

[0002] To meet the future application requirements of large underwater vehicles for all-weather, high-power, and long-endurance operation, advanced energy and propulsion technologies, as a key component of large underwater equipment, directly determine the equipment's self-sufficiency and operational detection capabilities. Fuel cells, as an electrochemical energy conversion device, can directly convert efficient and clean chemical energy into electrical energy. With no moving parts, they are characterized by quiet operation and zero emissions, thus finding increasing applications in large underwater equipment. For large underwater vehicles, due to limited internal space, achieving longer endurance and operational performance cannot be achieved by carrying unlimited energy. Therefore, improving overall system efficiency and reducing auxiliary power consumption within limited space becomes a crucial consideration for these vehicles. Summary of the Invention

[0003] In view of the above, and considering the requirements of large underwater transport platforms for the overall efficiency of fuel cell systems and the power consumption of auxiliary equipment, this invention proposes a closed-environment fuel cell cooling and thermoelectric power generation system and method.

[0004] To achieve the above objectives, the technical solution of the present invention is as follows: In a first aspect, this application provides a closed-environment fuel cell cooling and thermoelectric power generation system, including a fuel cell stack, a liquid oxygen cooling heat exchange component, a thermoelectric power generation plate group, a stack circulating water tank, and a cooling circulation regulation and heat dissipation component placed inside a pressure-resistant shell. The cooling water outlet of the fuel cell stack is connected to the inlet of the cooling circulation control and heat dissipation component, and both outlets of the cooling circulation control and heat dissipation component are connected to the inlet of the fuel cell stack's circulating water tank. The cooling circulation control and heat dissipation component is used to automatically switch the cooling flow path according to the circulating water temperature and to dissipate heat from the circulating water. The circulating water outlet of the liquid oxygen cooling heat exchanger is connected to the inlet of the fuel cell stack circulating water tank to input low-temperature circulating water into the fuel cell stack circulating water tank; The high-temperature surface of the thermoelectric generator unit is attached to the outer wall of the fuel cell stack circulating water tank, and the low-temperature surface is attached to the outer wall of the liquid oxygen cooling heat exchange component to form thermoelectric power generation. After passing through the circulating water pump, the outlet of the fuel cell stack circulating water tank is connected to the cooling circulating water inlet of the fuel cell stack on one side and to the circulating water inlet of the liquid oxygen cooling heat exchange component on the other side.

[0005] The further technical solution is that the cooling circulation regulation and heat dissipation component includes a thermostat, a first solenoid valve, a second solenoid valve, and an inter-hull heat exchange coil assembly placed inside the pressure-resistant shell. The thermostat inlet serves as the inlet of the cooling circulation regulation and heat dissipation component, connecting to the outlet of the fuel cell stack cooling circulating water. The first outlet of the thermostat serves as one outlet of the cooling circulation regulation and heat dissipation component, directly connecting to the first inlet of the fuel cell stack circulating water tank. The second outlet of the thermostat serves as another outlet of the cooling circulation regulation and heat dissipation component, sequentially connecting to the second inlet of the fuel cell stack circulating water tank via the first solenoid valve, the inter-hull heat exchange coil assembly, and the second solenoid valve. The thermostat is a temperature-controlled automatic flow path switching device used to automatically adjust the on / off state and flow rate of the two outlets based on the relationship between the circulating water temperature and the set temperature range.

[0006] The further technical solution is that if the current circulating water temperature is within the first set temperature range, the thermostat will activate the pipeline connected to the first outlet; if the current circulating water temperature is within the second set temperature range, the thermostat will activate the pipeline connected to the second outlet to meet the cooling requirements of different operating conditions. The first set temperature range is adapted to the temperature range of the fuel cell stack under low power operation conditions, and the second set temperature range is adapted to the temperature range of the fuel cell stack under high power operation conditions. The second set temperature range is higher than the first set temperature range, and the two temperature ranges do not overlap.

[0007] A further technical solution involves placing the pressure-resistant shell inside the lightweight outer shell, with seawater filling the space between them; The interhull heat exchange coil assembly is located in the interhull space between the pressure hull and the light outer shell to dissipate heat from the external seawater. The internal circulating water pipeline of the interhull heat exchange coil assembly is a low-pressure pipeline to prevent high-pressure seawater from being introduced into the pressure hull, while also saving space inside the pressure hull.

[0008] A further technical solution is that a first check valve is provided between the first solenoid valve and the inter-board heat exchange coil assembly on the pipeline connected to the second outlet of the thermostat, and a second check valve is provided between the inter-board heat exchange coil assembly and the second solenoid valve to prevent backflow of circulating water.

[0009] The further technical solution is that the liquid oxygen cooling heat exchange component is used to extract liquid oxygen cooling and transfer the cooling to the low temperature surface of the thermoelectric generator, including a liquid oxygen vaporizer and a heat conduction module conformally thereto. The shell-side circulating water outlet of the liquid oxygen vaporizer is connected to the inlet of the fuel cell stack circulating water tank as the circulating water outlet of the liquid oxygen cooling heat exchange component, and the shell-side circulating water inlet of the liquid oxygen vaporizer is connected to the outlet of the fuel cell stack circulating water tank as the circulating water inlet of the liquid oxygen cooling heat exchange component. The conformal heat-conducting module is fitted onto the outer wall of the liquid oxygen vaporizer and is in close contact with the low-temperature surface of the thermoelectric generator assembly.

[0010] The further technical solution is that the system also includes a liquid oxygen tank, an oxygen buffer tank, and an oxygen temperature sensor; The liquid oxygen tank outlet is connected to the medium inlet of the liquid oxygen vaporizer, and the gas oxygen outlet of the liquid oxygen vaporizer is connected to the oxygen inlet of the fuel cell stack via an oxygen buffer tank and an oxygen temperature sensor in sequence. The oxygen buffer tank is used to store high-pressure oxygen to maintain a stable gas supply to the fuel cell stack.

[0011] The further technical solution is that the system also includes an energy storage battery and a 24V power supply; The power output terminal of the thermoelectric generator is connected to the energy storage battery. The energy storage battery is connected to the DC24V power grid of the system via a 24V power supply to power the auxiliary equipment, thereby reducing the power consumption of the system's auxiliary equipment.

[0012] The further technical solution is that the system also includes several circulating water temperature sensors and pressure sensors; The circulating water temperature sensors are respectively arranged at the inlet and outlet of the fuel cell stack, inside the circulating water tank of the stack, at the inlet of the circulating water of the liquid oxygen cooling heat exchange component, and at the inlet and outlet of the cooling circulation regulation and heat dissipation component. The pressure sensor is located in the circulating water pipeline between the circulating water pump and the fuel cell stack.

[0013] Secondly, this application also provides a method for cooling and thermoelectric power generation of a fuel cell in a closed environment. This method is based on the closed-environment fuel cell cooling and thermoelectric power generation system described in the first aspect, and includes the following steps: Liquid oxygen is vaporized by absorbing heat from the liquid oxygen cooling heat exchange component, forming gaseous oxygen that is stably supplied to the fuel cell stack. The circulating water pump drives the circulating water in the fuel cell stack's circulating water tank to split into two streams. One stream enters the fuel cell stack to absorb working heat and complete the cooling process, while the other stream enters the liquid oxygen cold energy exchange component to absorb liquid oxygen and form low-temperature circulating water. The cooling circulation control heat dissipation component automatically switches to the cooling flow path adapted to the high / low power operation conditions of the fuel cell stack based on the real-time temperature of the circulating water, and performs differentiated heat dissipation on the circulating water. High-temperature circulating water that absorbs heat from the fuel cell stack and low-temperature circulating water that absorbs the cooling energy of liquid oxygen are mixed in the fuel cell stack circulating water tank to reduce the overall temperature of the circulating water. Thermoelectric generators utilize the temperature difference between the high temperature of the fuel cell stack's circulating water tank and the low temperature of the liquid oxygen cooling heat exchange components to generate electricity, which powers the system's auxiliary equipment.

[0014] The beneficial technical effects of this invention are: 1. This system vaporizes liquid oxygen into gaseous oxygen through a liquid oxygen vaporizer, and then cools the fuel cell stack with circulating water in the stack's circulating water tank. It makes full use of the temperature difference between the cold energy of the cryogenic liquid oxygen and the heat generated by the fuel cell stack, and generates electricity through the thermoelectric generator array. This effectively utilizes the waste heat and waste cold energy of the fuel cell system, thus improving system efficiency.

[0015] 2. This system stores the electrical energy generated by the thermoelectric generator set in an energy storage battery and supplies it to the DC24V power grid of the system via a 24V power supply to power the auxiliary equipment in the system. This effectively reduces the main power consumption of the transport platform and indirectly reduces the power consumption of the auxiliary equipment in the system.

[0016] 3. In this system, the circulating water in the liquid oxygen vaporizer vaporizes the liquid oxygen and then returns it to the fuel cell stack circulating water tank as low-temperature circulating water. It mixes thoroughly with the circulating water coming out of the fuel cell stack. In this way, the cold energy of the low-temperature liquid oxygen is used to lower the temperature of the circulating water in the fuel cell stack circulating water tank, thereby indirectly cooling the fuel cell stack through the cold energy of the liquid oxygen. This fully realizes the cascade utilization of the system's thermal energy, effectively reduces the size of the fuel cell stack circulating water tank and the number of equipment required, and improves the system's thermal efficiency.

[0017] 4. This system employs a thermostat, which automatically adjusts the circulating water entering the fuel cell stack's circulating water tank and the inter-board heat exchange coil assembly according to the set temperature range, thus achieving automatic switching of the circulating water cooling flow path when the fuel cell stack is operating at low power and high power.

[0018] 5. Traditional cooling systems place the heat exchanger inside the pressure hull, which introduces high-pressure seawater from outside into the pressure hull. Due to the numerous leakage points of the heat exchanger, there is a risk of significant seawater leakage into the pressure hull. In contrast, this system places the inter-hull heat exchange coil assembly between the pressure hull and the outer shell, essentially placing the inter-hull heat exchange coil assembly outside the pressure hull. The circulating water pipeline inside the inter-hull heat exchange coil assembly is a low-pressure pipeline, effectively avoiding the risk of high-pressure seawater being introduced into the pressure hull and causing high-pressure seawater from outside to enter the cabin. This greatly improves the system's sea passage safety. In addition, it effectively utilizes the unused space in the inter-hull, saving space inside the pressure hull. Attached Figure Description

[0019] Figure 1 This is a structural diagram of the closed-environment fuel cell cooling and thermoelectric power generation system provided in this application; Figure 2 This is a cross-sectional schematic diagram of the liquid oxygen cooling heat exchange component and the thermoelectric generator assembly provided in this application.

[0020] In the diagram: 1-Fuel cell stack, 2-Circulating water temperature sensor, 3-Thermostat, 4-First solenoid valve, 5-First check valve, 6-Inter-hull heat exchange coil assembly, 7-Second check valve, 8-Second solenoid valve, 9-Circulating water temperature sensor, 10-Liquid oxygen tank, 11-Liquid oxygen vaporizer, 12-Conformal heat conduction module, 13-Thermoelectric generator assembly, 14-Fuel cell stack circulating water tank, 15-Circulating water temperature sensor, 16-Circulating water temperature sensor, 17-Oxygen buffer tank, 18-Oxygen temperature sensor, 19-Energy storage battery, 20-24V power supply, 21-Circulating water pump, 22-Pressure sensor, 23-Circulating water temperature sensor, 24-Pressure-resistant housing, 25-Lightweight housing Detailed Implementation The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0021] The following detailed description, based on the system's structure and workflow, provides a specific implementation method for a closed-environment fuel cell cooling and thermoelectric power generation system. This embodiment is applicable to fuel cell power systems of large-scale closed underwater transport platforms. Please refer to... Figure 1 As shown, the closed-environment fuel cell cooling and thermoelectric power generation system disclosed in this embodiment includes the following components fixedly installed inside the pressure-resistant housing: fuel cell stack 1, liquid oxygen tank 10, thermoelectric power generation plate group 13, stack circulating water tank 14, oxygen buffer tank 17, energy storage battery 19, 24V power supply 20, circulating water pump 21, liquid oxygen cooling heat exchange component and various sensors, as well as thermostat 3, first solenoid valve 4 and second solenoid valve 8 in the cooling circulation regulation and heat dissipation component.

[0022] In this embodiment, the pressure hull 24 is the core pressure-bearing chamber of the underwater transport platform, made of titanium alloy to withstand seawater back pressure, and its interior is a sealed environment at atmospheric pressure. The lightweight outer shell 25 is the shell that maintains the external shape of the underwater transport platform, encasing the pressure hull. The interplane space between the two is filled with seawater for external heat exchange. The interplane space is equipped with the interplane heat exchange coil assembly 6, a spiral-shaped heat exchange device with corresponding pressure resistance. Its internal circulating water pipeline is a low-pressure pipeline, which can dissipate heat with the high-pressure seawater, thus avoiding the risk of seawater leakage and saving internal space of the pressure hull.

[0023] The fuel cell stack 1 is a power generation device that uses hydrogen as fuel and oxygen as oxidant to convert chemical energy into electrical energy through an electrochemical reaction. The liquid oxygen tank 10 is used to store cryogenic liquid oxygen at temperatures such as -183°C. It consists of an inner tank, an outer tank, and a jacketed structure. The inner and outer tanks maintain a certain level of insulation through insulating materials distributed in the jacketed structure and a vacuum system. The oxygen buffer tank 17 is used to store high-pressure oxygen and maintain a stable gas supply to the fuel cell. When the fuel cell stack experiences load changes, this device maintains a stable oxygen supply. The circulating water pump 21 is used to provide pressure head for the circulating water in the pipeline.

[0024] For the cooling circulating water connection, the required component connections are as follows: the cooling circulating water outlet of fuel cell stack 1 is connected to the thermostat inlet of the cooling circulation regulation and heat dissipation component; both outlets of the cooling circulation regulation and heat dissipation component are connected to the inlet of the stack circulating water tank. The circulating water outlet of the liquid oxygen cold energy heat exchange component is connected to the inlet of the stack circulating water tank, used to input low-temperature circulating water into the stack circulating water tank 14. After passing through the circulating water pump 21, the outlet of the stack circulating water tank is connected in two ways: one to the cooling circulating water inlet of fuel cell stack 1 (stack cooling flow path), and the other to the circulating water inlet of the liquid oxygen cold energy heat exchange component (cold energy extraction flow path).

[0025] For the connection between thermoelectric power generation and power supply, the required component connection relationship is as follows: the high-temperature surface of the thermoelectric generator assembly 13 is attached to the outer wall of the fuel cell circulating water tank 14, and the low-temperature surface is attached to the outer wall of the liquid oxygen cooling heat exchange component to form thermoelectric power generation. The power output terminal of the thermoelectric generator assembly 13 is connected to the energy storage battery 19. The energy storage battery 19 is connected to the system's DC24V power grid via a 24V power supply 20 to power auxiliary equipment (such as valves, sensors, circulating water pumps, etc.) to reduce the power consumption of system auxiliary equipment. Among them, the thermoelectric generator assembly 13 is based on the first thermoelectric effect (Seebeck effect) principle, which uses temperature difference to directly convert heat energy into electrical energy. In this system, multiple thermoelectric generators are connected in series and parallel to form the thermoelectric generator assembly 13.

[0026] In this embodiment, the cooling circulation regulation and heat dissipation component is used to automatically switch the cooling flow path according to the circulating water temperature and dissipate heat from the circulating water. This component specifically includes a thermostat 3, a first solenoid valve 4, a first check valve 5, an inter-hull heat exchange coil assembly 6, a second check valve 7, and a second solenoid valve 8. The first outlet of the thermostat serves as one outlet of the cooling circulation regulation and heat dissipation component and is directly connected to the first inlet (internal circulation flow path) of the fuel cell stack circulating water tank 14. The second outlet of the thermostat serves as another outlet of the cooling circulation regulation and heat dissipation component and is connected to the second inlet (external circulation heat dissipation flow path) of the fuel cell stack circulating water tank 14 via the first solenoid valve 4, the first check valve 5, the inter-hull heat exchange coil assembly 6, the second check valve 7, and the second solenoid valve 8. The two solenoid valves 4 and 8 are valves whose on / off state can be controlled by energizing or de-energizing; this system is used to connect or disconnect the corresponding pipelines. The two check valves 5 and 7 are valves that can pass through in one direction and shut off in the reverse direction to prevent backflow of circulating water.

[0027] The thermostat 3 is a temperature-controlled automatic flow path switching device used to automatically adjust the on / off state and flow rate of the two outlets based on the relationship between the circulating water temperature and the set temperature range. For example, if the current circulating water temperature is within the first set temperature range, the thermostat activates the pipe connected to the first outlet, i.e., the internal circulation flow path; if the current circulating water temperature is within the second set temperature range, the thermostat activates the pipe connected to the second outlet, i.e., the external circulation heat dissipation flow path, to meet the cooling requirements of different operating conditions. In this embodiment, the first set temperature range is adapted to the temperature range of the fuel cell stack under low-power operating conditions (e.g., ≤60℃), and the second set temperature range is adapted to the temperature range of the fuel cell stack under high-power operating conditions (e.g., >60℃). It should be noted that the two temperature ranges do not overlap, ensuring that the flow path switching is conflict-free.

[0028] In this embodiment, the liquid oxygen cooling heat exchange component is used to extract liquid oxygen cooling and transfer it to the low-temperature surface of the thermoelectric generator array. This component includes a liquid oxygen vaporizer 11 and a conformally fitted heat-conducting module 12. The shell-side circulating water outlet of the liquid oxygen vaporizer 11 serves as the circulating water outlet of the liquid oxygen cooling heat exchange component and is connected to the inlet of the fuel cell stack circulating water tank. The shell-side circulating water inlet of the liquid oxygen vaporizer 11 serves as the circulating water inlet of the liquid oxygen cooling heat exchange component and is connected to the outlet of the fuel cell stack circulating water tank. For the oxygen supply pipeline connection, the required component connection relationship is as follows: the liquid oxygen tank outlet is connected to the medium inlet of the liquid oxygen vaporizer 11, and the gaseous oxygen outlet of the liquid oxygen vaporizer 11 is connected to the oxygen inlet of the fuel cell stack 1. Optionally, the oxygen buffer tank 17 and the oxygen temperature sensor 18 are connected in series in the oxygen pipeline. Among them, the liquid oxygen vaporizer 11 is a device that can exchange heat with liquid oxygen or cryogenic gaseous oxygen (distributed in the upper layer of the liquid oxygen tank). After the liquid oxygen or cryogenic gaseous oxygen flows into the vaporizer, it undergoes sufficient heat exchange with the circulating water inside the vaporizer, thus vaporizing the liquid oxygen or heating the cryogenic gaseous oxygen to room temperature gas. Figure 2As shown, the conformal heat conduction module 12 is composed of copper sheet components with good thermal conductivity, conformally attached to the outer wall of the liquid oxygen vaporizer 11, and closely attached to the low-temperature surface of the thermoelectric generator assembly 13.

[0029] Optionally, the system also includes five circulating water temperature sensors 2, 9, 15, 16, and 23, and a pressure sensor 22. The circulating water temperature sensors 2, 9, 15, 16, and 23 are respectively located at the inlet and outlet of the fuel cell stack, inside the fuel cell stack circulating water tank, at the circulating water inlet of the liquid oxygen cooling heat exchange component, and at the inlet and outlet of the cooling circulation control heat dissipation component (specifically distributed at the outlet of the external circulation heat dissipation flow path) to monitor the circulating water temperature. The pressure sensor 22 is located in the circulating water pipeline between the circulating water pump 21 and the fuel cell stack 1 to monitor the cooling water pressure. The oxygen temperature sensor 18 is installed between the oxygen buffer tank 17 and the fuel cell stack 1 to monitor the gas supply temperature.

[0030] The main function of the aforementioned closed-environment fuel cell cooling and thermoelectric power generation system is to vaporize cryogenic liquid oxygen stored in the liquid oxygen tank 10 into gaseous oxygen via the liquid oxygen vaporizer 11 for use during the operation of the fuel cell stack 1. The heat generated during the operation of the fuel cell stack is ultimately carried to the stack circulating water tank 14 via circulating water, fully utilizing the temperature difference between the cold energy of the cryogenic liquid oxygen and the heat generated by the fuel cell stack, enabling the thermoelectric power generation unit 13 to generate electricity. This effectively utilizes the waste heat and waste cooling of the fuel cell system, improving system efficiency. The system is powered by a 24V DC 24V grid for power generation. Powering auxiliary equipment in the system effectively reduces the main power consumption of the transport platform, indirectly reducing the power consumption of the auxiliary equipment. In this system, the circulating water inside the liquid oxygen vaporizer 11 vaporizes the liquid oxygen and finally returns it to the fuel cell stack circulating water tank 14, where it is fully mixed with the circulating water coming out of the fuel cell stack 1. This utilizes the cold energy of the cryogenic liquid oxygen to lower the temperature of the circulating water in the fuel cell stack circulating water tank, indirectly achieving cooling of the fuel cell stack through the cold energy of the liquid oxygen. This fully realizes the cascade utilization of the system's thermal energy, effectively reduces the size of the fuel cell stack circulating water tank and the number of equipment configurations, and improves the system's thermal efficiency. The thermostat 3 automatically adjusts the flow path of the circulating water from the fuel cell stack 1 to either the stack circulating water tank 14 or the interplane heat exchange coil assembly 6, based on the set temperature range. This enables automatic switching of the circulating water flow between low-power and high-power operation of the fuel cell stack 1. By placing the interplane heat exchange coil assembly 6 outside the pressure hull 24, and ensuring that the circulating water pipeline inside the interplane heat exchange coil assembly 6 is a low-pressure pipeline, the risk of high-pressure seawater entering the cabin due to the introduction of high-pressure seawater into the pressure hull can be effectively avoided, greatly improving the safety of the system for sea passage. In addition, the ineffective space in the interplane is effectively utilized, saving the arrangement space inside the pressure hull.

[0031] One embodiment of this application also provides a method for cooling and thermoelectric power generation of a fuel cell in a closed environment using the above-described system, specifically including the following steps: Step 1: Liquid oxygen vaporization and oxygen supply. Liquid oxygen is vaporized by absorbing heat from the liquid oxygen cooling heat exchange component, forming gaseous oxygen that is stably supplied to fuel cell stack 1. Specifically, this includes: When the fuel cell stack 1 is operating, the cryogenic liquid oxygen in the liquid oxygen tank 10 flows into the liquid oxygen vaporizer 11, where it vaporizes into room-temperature gaseous oxygen after heat exchange with the shell-side circulating water. This gaseous oxygen then enters the oxygen buffer tank 17 for pressure stabilization. After temperature measurement by the oxygen temperature sensor 18, it is stably delivered to the fuel cell stack 1 to provide oxidant for the electrochemical reaction. In addition, when the power of the fuel cell stack 1 changes, the oxygen buffer tank 17 performs peak shaving and valley filling to maintain a stable oxygen supply pressure in the pipeline.

[0032] Step 2: Circulating water flow and cold extraction After the circulating water pump 21 starts, the circulating water in the fuel cell stack circulating water tank 14 enters the fuel cell stack 1 through the pressure sensor 22 and the temperature sensor 23, absorbs the heat generated by the stack operation, and becomes high-temperature circulating water; the other path enters the shell side of the liquid oxygen vaporizer, absorbs the cold energy of the liquid oxygen and becomes low-temperature circulating water of 5-8℃, and flows directly back to the fuel cell stack circulating water tank 14 to reduce the overall water temperature in the tank.

[0033] Step 3: Automatic Cooling Flow Path Switching (Different Operating Conditions). The cooling circulation control and heat dissipation components automatically switch to the appropriate cooling flow path based on the real-time temperature of the circulating water, adapting to the high / low power operating conditions of the fuel cell stack, thus providing differentiated heat dissipation for the circulating water. Specifically, this includes: 1) Internal circulation heat exchange in fuel cell stack When the fuel cell stack 1 is started or running at low power, the heat generated is relatively small, and the circulating water temperature is usually ≤60℃. At this time, the thermostat 3 only opens the first outlet, and the high-temperature circulating water that absorbs the heat of the stack flows directly back to the stack circulating water tank 14 through the internal circulation path. It mixes with the low-temperature circulating water that absorbs the cooling capacity of liquid oxygen to reduce the overall temperature of the circulating water and complete the low-power cooling.

[0034] 2) External circulation cooling of fuel cell stack When the fuel cell stack 1 is running at high power, it generates a lot of heat. The circulating water temperature is usually >60℃. The temperature of the circulating water stored in the stack circulating water tank 14 gradually increases and is not enough to completely remove the heat generated by the fuel cell stack 1. At this time, the thermostat 3 automatically opens the second outlet, and the first solenoid valve 4 and the second solenoid valve 8 open simultaneously. The high-temperature circulating water passes through the first solenoid valve 4 and the first one-way valve 5 in sequence, passes through the pressure-resistant shell 24 and enters the inter-hull heat exchange coil group 6 to exchange heat with the inter-hull seawater. The cooled water passes through the second one-way valve 7, the second solenoid valve 8 and the temperature sensor 9 in sequence and then flows back to the stack circulating water tank 14 to meet the high-power cooling requirements.

[0035] Step 4: Thermoelectric power generation and energy utilization. Thermoelectric generator unit 13 utilizes the temperature difference between the high temperature of the fuel cell stack circulating water tank 14 and the low temperature of the liquid oxygen cooling heat exchange component to generate electricity, which powers the system's auxiliary equipment. Specifically, this includes: The circulating water in the fuel cell stack circulating water tank 14 absorbs the heat generated during the operation of the fuel cell stack 1, and its temperature is around 60-65℃. The outer wall (bottom) of the circulating water tank serves as the high-temperature surface of the thermoelectric generator assembly 13. The liquid oxygen vaporizer 11 contains cryogenic liquid oxygen at -183℃ on the tube side. After the circulating water on the shell side vaporizes the cryogenic liquid oxygen, its temperature is around 5-8℃. Its cooling energy is transferred to the conformal heat conduction module 12 through the outer wall of the liquid oxygen vaporizer 11, serving as the low-temperature surface of the thermoelectric generator assembly 13, forming a stable temperature difference between the two ends. The thermoelectric generator assembly 13 converts thermal energy into electrical energy based on the Seebeck effect. The electrical energy is stored in the energy storage battery 19, and after being regulated by the 24V power supply 20, it is connected to the system's DC 24V power grid to power auxiliary equipment such as the circulating water pump, solenoid valves, and sensors, reducing the main power consumption.

[0036] The above descriptions are merely preferred embodiments of this application, and the present invention is not limited to the above embodiments. It is understood that other improvements and variations directly derived or conceived by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included within the protection scope of the present invention.

Claims

1. A closed-environment fuel cell cooling and thermoelectric power generation system, characterized in that, It includes a fuel cell stack, a liquid oxygen cooling heat exchange assembly, a thermoelectric generator array, a stack circulating water tank, and a cooling circulation regulation and heat dissipation assembly, all housed inside a pressure-resistant casing. The cooling circulating water outlet of the fuel cell stack is connected to the inlet of the cooling circulation regulation and heat dissipation component, and both outlets of the cooling circulation regulation and heat dissipation component are connected to the inlet of the fuel cell stack circulating water tank; the cooling circulation regulation and heat dissipation component is used to automatically switch the cooling flow path according to the circulating water temperature and to dissipate heat from the circulating water. The circulating water outlet of the liquid oxygen cooling heat exchange component is connected to the inlet of the fuel cell stack circulating water tank, and is used to input low temperature circulating water into the fuel cell stack circulating water tank; The high-temperature surface of the thermoelectric generator assembly is attached to the outer wall of the fuel cell circulating water tank, and the low-temperature surface is attached to the outer wall of the liquid oxygen cooling heat exchange component to form thermoelectric power generation. After passing through the circulating water pump, the outlet of the fuel cell stack circulating water tank is connected to the cooling circulating water inlet of the fuel cell stack on one side and to the circulating water inlet of the liquid oxygen cooling heat exchange component on the other side.

2. The closed-environment fuel cell cooling and thermoelectric power generation system according to claim 1, characterized in that, The cooling cycle regulation and heat dissipation assembly includes a thermostat, a first solenoid valve, a second solenoid valve, and an inter-hull heat exchange coil assembly, all housed inside the pressure-resistant housing. The thermostat inlet serves as the inlet of the cooling cycle regulation and heat dissipation component and is connected to the outlet of the fuel cell stack cooling circulating water. The first outlet of the thermostat serves as one outlet of the cooling cycle regulation and heat dissipation component and is directly connected to the first inlet of the fuel cell stack circulating water tank. The second outlet of the thermostat serves as another outlet of the cooling cycle regulation and heat dissipation component and is connected to the second inlet of the fuel cell stack circulating water tank via the first solenoid valve, the inter-hull heat exchange coil assembly, and the second solenoid valve. The thermostat is a temperature-controlled automatic flow path switching device used to automatically adjust the on / off state and flow rate of the two outlets based on the relationship between the circulating water temperature and the set temperature range.

3. The closed-environment fuel cell cooling and thermoelectric power generation system according to claim 2, characterized in that, If the current circulating water temperature is within the first set temperature range, the thermostat activates the pipe connected to the first outlet; if the current circulating water temperature is within the second set temperature range, the thermostat activates the pipe connected to the second outlet to meet the cooling requirements of different operating conditions. The first set temperature range is adapted to the temperature range of the fuel cell stack under low power operation conditions, the second set temperature range is adapted to the temperature range of the fuel cell stack under high power operation conditions, the second set temperature range is higher than the first set temperature range, and the two temperature ranges have no overlapping intervals.

4. The closed-environment fuel cell cooling and thermoelectric power generation system according to claim 2, characterized in that, The pressure-resistant shell is placed inside the lightweight outer shell, with seawater filling the space between them; The interhull heat exchange coil assembly is located in the interhull space between the pressure hull and the lightweight outer shell, and dissipates heat from the external seawater. The internal circulating water pipeline of the interhull heat exchange coil assembly is a low-pressure pipeline, which is used to prevent high-pressure seawater from being introduced into the pressure hull, and at the same time saves the internal layout space of the pressure hull.

5. The closed-environment fuel cell cooling and thermoelectric power generation system according to claim 1, characterized in that, The liquid oxygen cooling heat exchange component is used to extract liquid oxygen cooling and transfer the cooling to the low-temperature surface of the thermoelectric generator array, including a liquid oxygen vaporizer and a heat conduction module conformally thereto. The shell-side circulating water outlet of the liquid oxygen vaporizer is connected to the inlet of the fuel cell stack circulating water tank as the circulating water outlet of the liquid oxygen cooling heat exchange component, and the shell-side circulating water inlet of the liquid oxygen vaporizer is connected to the outlet of the fuel cell stack circulating water tank as the circulating water inlet of the liquid oxygen cooling heat exchange component. The conformal heat-conducting module is fitted onto the outer wall of the liquid oxygen vaporizer and is in close contact with the low-temperature surface of the thermoelectric generator assembly.

6. The closed-environment fuel cell cooling and thermoelectric power generation system according to claim 5, characterized in that, The system also includes a liquid oxygen tank, an oxygen buffer tank, and an oxygen temperature sensor; The liquid oxygen tank outlet is connected to the medium inlet of the liquid oxygen vaporizer, and the gaseous oxygen outlet of the liquid oxygen vaporizer is connected to the oxygen inlet of the fuel cell stack via the oxygen buffer tank and the oxygen temperature sensor in sequence. The oxygen buffer tank is used to store high-pressure oxygen to maintain a stable gas supply to the fuel cell stack.

7. The closed-environment fuel cell cooling and thermoelectric power generation system according to claim 1, characterized in that, The system also includes an energy storage battery and a 24V power supply; The power output terminal of the thermoelectric generator is connected to the energy storage battery. The energy storage battery is connected to the DC24V power grid of the system via a 24V power supply to power the auxiliary equipment, thereby reducing the power consumption of the system auxiliary equipment.

8. The closed-environment fuel cell cooling and thermoelectric power generation system according to claim 1, characterized in that, The system also includes several circulating water temperature sensors and pressure sensors; The circulating water temperature sensors are respectively arranged at the inlet and outlet of the fuel cell stack, inside the circulating water tank of the stack, at the circulating water inlet of the liquid oxygen cooling heat exchange component, and at the inlet and outlet of the cooling circulation regulation and heat dissipation component. The pressure sensor is located in the circulating water pipeline between the circulating water pump and the fuel cell stack.

9. The closed-environment fuel cell cooling and thermoelectric power generation system according to claim 2, characterized in that, On the pipeline connected to the second outlet of the thermostat, a first check valve is provided between the first solenoid valve and the inter-board heat exchange coil assembly, and a second check valve is provided between the inter-board heat exchange coil assembly and the second solenoid valve, to prevent backflow of circulating water.

10. A method for cooling and thermoelectric power generation of a fuel cell in a closed environment, characterized in that, The method is implemented based on the closed-environment fuel cell cooling and thermoelectric power generation system according to any one of claims 1-9, and includes the following steps: Liquid oxygen is vaporized by absorbing heat from the liquid oxygen cooling heat exchange component, forming gaseous oxygen that is stably supplied to the fuel cell stack. The circulating water pump drives the circulating water in the fuel cell stack circulating water tank to split into two streams. One stream enters the fuel cell stack to absorb working heat and complete cooling, while the other stream enters the liquid oxygen cooling heat exchange component to absorb liquid oxygen and form low-temperature circulating water. The cooling circulation regulation and heat dissipation component automatically switches the cooling flow path to adapt to the high / low power operation conditions of the fuel cell stack according to the real-time temperature of the circulating water, and performs differentiated heat dissipation on the circulating water. High-temperature circulating water that absorbs heat from the fuel cell stack and low-temperature circulating water that absorbs the cooling energy of liquid oxygen are mixed in the fuel cell stack circulating water tank to reduce the overall temperature of the circulating water. The thermoelectric generator unit utilizes the temperature difference between the high temperature of the fuel cell circulating water tank and the low temperature of the liquid oxygen cooling heat exchange component to generate electricity to power the system's auxiliary equipment.

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