Fuel cell circulating water system for underwater, closed compartments and operating process

Abstract

A fuel cell circulating water system and operation process for underwater sealed cabin, including pressure hull, conformal heat exchange water tank, metal hose, electromagnetic valve, spiral heat exchange pipe group, temperature control tee valve, inner rib, fuel cell stack, circulating water tank, long continuous electronic equipment, circulating water pump, outer rib, cylindrical vacuum insulation board, light shell, etc. The spiral heat exchange pipe group is arranged between the inner ribs, which makes full use of the space between the inner ribs and the arc segment of the pressure hull, which is difficult to use, and avoids introducing seawater into the cabin for cooling by means of heat transfer through the bulkhead. Not only the equipment and pipeline of the traditional cooling method are saved, the auxiliary power consumption of the system is effectively reduced, but also the opening of the seawater pipeline on the pressure hull is avoided, the structural safety of the underwater carrier platform is effectively improved. The stack is always in the appropriate working temperature range, the heat loss is effectively reduced, and the system efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of fuel cell power system technology for underwater transport platforms, and in particular to a fuel cell circulating water system and its operation process for use in underwater sealed compartments. Background Technology

[0002] As an electrochemical energy conversion device, fuel cells can directly convert chemical energy into electrical energy efficiently and cleanly. They have no moving parts, are quiet, emit no exhaust gases, and have low infrared signatures. Therefore, they are increasingly being used in deep-sea equipment. For underwater transport platforms weighing several hundred tons, in order to achieve strong operational capabilities and endurance, in addition to carrying a large amount of energy, one effective approach is to rationally optimize the layout and number of equipment based on the performance of each component, simplify the system, and fully utilize the waste heat generated by the system to achieve optimal space utilization within the cabin and optimize the efficiency of the power system.

[0003] In fuel cell-powered underwater platforms, chemical energy is directly converted into electrical energy through an electrochemical reaction between the hydrogen and oxygen carried, thus continuously powering the load. However, during operation, not all energy is converted into electrical energy; some energy is ultimately manifested as heat. Therefore, circulating water is needed to remove the heat generated during normal operation of the fuel cell stack. Traditional fuel cell circulating water systems typically have three stages: the first stage is fuel cell stack circulating water for cooling the stack; the second stage is fresh water for cooling the fuel cell stack circulating water and other equipment; and the third stage is a seawater system that carries the heat from the fresh water in the second stage to the surrounding seawater. Such fuel cell circulating water systems have the following problems: First, the system is quite complex, requiring the configuration of multiple stages of piping and heat exchangers, etc. Secondly, introducing the seawater system into the pressure hull requires openings in the pressure hull, which not only reduces the structural safety of the pressure hull, but also requires consideration of the impact of seawater system pipeline damage on the safety of the underwater transport platform. Third, in order to enhance its pressure resistance, the pressure shell is equipped with internal ribs, but the space between the internal ribs is difficult to utilize effectively, which affects the overall equipment layout and performance optimization.

[0004] Therefore, it is evident that optimizing equipment layout and quantity, simplifying the system, making full use of unusable space within the cabin, and improving system efficiency are crucial for enhancing the operational capabilities and endurance of underwater transport platforms. Summary of the Invention

[0005] Considering the requirements for optimizing the configuration of equipment, systems, and internal space of the pressure-resistant shell of the fuel cell power system for underwater transport platforms, and improving system efficiency, the applicant provides a fuel cell circulating water system and its operation process for underwater sealed compartments. This system fully utilizes the space between the inner ribs and the arc section of the pressure-resistant shell, which are often difficult to utilize, by setting spiral heat exchange tube groups between the inner ribs. Heat transfer through the cabin walls avoids the need to introduce seawater into the cabin for system cooling. This not only eliminates the need for equipment and piping in traditional seawater cooling systems, effectively reducing the power consumption of auxiliary equipment, but also avoids openings in the pressure-resistant shell for seawater piping, effectively improving the structural safety of the underwater transport platform.

[0006] The technical solution adopted in this invention is as follows: A fuel cell circulating water system for an underwater sealed chamber includes a pressure-resistant shell. A conformal heat exchange tank is disposed inside the pressure-resistant shell. An annular space is formed between the inner wall of the pressure-resistant shell and the outer wall of the conformal heat exchange tank. A cylindrical vacuum insulation panel is installed in the upper half of this annular space, closely attached to the inner wall of the pressure-resistant shell. A first spiral heat exchange tube assembly and a second spiral heat exchange tube assembly, symmetrically arranged on both sides, are installed in the lower half of this annular space. The system also includes a fuel cell stack installed inside the pressure-resistant shell. One end of the fuel cell stack is connected in series via a circulating water tank, a circulating water pump, and a temperature-controlled three-way valve. One path of the temperature-controlled three-way valve is connected to the first spiral heat exchange tube assembly via a first solenoid valve, and the other path is connected to the second spiral heat exchange tube assembly via a second solenoid valve. The temperature-controlled three-way valve is also connected to the fuel cell stack via a first return pipe. The bottoms of the first and second spiral heat exchange tube assemblies are connected by a connecting pipe. A second return pipe is disposed between the first return pipe and the connecting pipe. The outer wall of the pressure-resistant shell is welded with outer ribs at intervals along the axial direction, and the inner wall of the pressure-resistant shell is welded with inner ribs at intervals along the axial direction. The inner ribs correspond to the outer ribs, and each inner rib has a hole in the middle. It also includes a No. 3 spiral heat exchange tube group and a No. 4 spiral heat exchange tube group symmetrically arranged in the lower half of the annular space. The No. 3 spiral heat exchange tube group and the No. 4 spiral heat exchange tube group pass through the holes opened in the inner ribs. The bottom of the No. 3 spiral heat exchange tube group is connected to the connecting pipe through a No. 1 metal flexible tube, and the bottom of the No. 4 spiral heat exchange tube group is connected to the connecting pipe through a No. 4 metal flexible tube. One of the three-way temperature control valves is also connected to the top of the No. 3 spiral heat exchange tube group through a No. 3 solenoid valve and a No. 2 metal flexible tube, and the other is connected to the top of the No. 4 spiral heat exchange tube group through a No. 4 solenoid valve and a No. 3 metal flexible tube. The pressure-resistant housing is also fitted with a lightweight outer shell.

[0007] Its further technical solution lies in: The pressure-resistant hull is a pressure-bearing, sealed chamber capable of withstanding the back pressure of seawater, and the interior of the chamber is used to house system equipment.

[0008] The No. 1 spiral heat exchanger tube group, the No. 2 spiral heat exchanger tube group, the No. 3 spiral heat exchanger tube group, and the No. 4 spiral heat exchanger tube group have the same structure, all of which use a mixture of straight tubes and spiral tubes.

[0009] The straight sections of the No. 3 and No. 4 spiral heat exchanger tube groups pass through the openings in the inner ribs.

[0010] Both the outer and inner ribs are made of ring-shaped rib plates.

[0011] The space between the pressure-resistant shell and the lightweight outer shell is filled with seawater.

[0012] The cylindrical vacuum insulation panel uses environmentally friendly heat insulation materials.

[0013] An operation process for a fuel cell circulating water system for an underwater sealed compartment includes the following steps: Step 1: Automatic distribution and adjustment of heat dissipation in fuel cell stack circulating water cooling system: When the fuel cell stack undergoes a cold start, the circulating water inside is initially at a low temperature and is being heated by the stack. Therefore, it does not require further cooling via the spiral heat exchanger tube assembly. The circulating water then returns to the fuel cell stack via the circulating water tank, circulating water pump, and temperature-controlled three-way valve. When the fuel cell stack is in continuous operation and requires cooling, the circulating water returns to the fuel cell stack via the circulating water tank, circulating water pump, temperature-controlled three-way valve, solenoid valve number one, and spiral heat exchanger tube assembly number one. When the fuel cell stack power increases and a single spiral heat exchanger tube assembly cannot meet the cooling requirements, solenoid valves number two, three, and four are controlled to increase the number of spiral heat exchanger tube assemblies in operation, ensuring continuous cooling of the stack. Conversely, when the fuel cell stack power decreases, the number of spiral heat exchanger tube assemblies in operation is reduced by controlling the solenoid valves. This automatic distribution and adjustment of the circulating water in the stack is achieved through the temperature-controlled three-way valve and the control of the number of spiral heat exchanger tube assemblies in operation. Step 2: Effectively utilize the space within the inner ribs to achieve heat exchange via spiral heat exchange tube assemblies: When the fuel cell stack needs to be loaded or run at high power continuously, the circulating water in all the spiral heat exchange tube groups is at a high temperature and needs to be cooled to ensure that the stack continues to work in the best condition. Therefore, the cooling water in the conformal circulating water tank is needed to exchange heat and cool it, so as to ensure that the heat in the stack circulating water is carried away by the cooling water in the conformal circulating water tank in time. Step 3: Heat transfer through the pressure hull walls: As the heat of the circulating water in the multiple sets of spiral heat exchange tubes is continuously exchanged with the cooling water in the conformal circulating water tank, the temperature of the cooling water in the conformal circulating water tank will gradually rise. When it rises to 20 to 30 degrees Celsius, there is a temperature difference between the cooling water in the conformal circulating water tank and the seawater between the pressure hull and the outer shell. In this way, the heat of the cooling water in the conformal circulating water tank will be finally discharged to the outside of the pressure hull through the heat transfer of the pressure hull walls. Step 4: Long-term continuous cooling of electronic equipment: When the long-term continuous electronic equipment is working normally, it will also emit a certain amount of heat. At this time, the circulating water in the circulating water tank will return to the circulating water tank through the circulating water pump, temperature control three-way valve, solenoid valve, spiral heat exchange tube group, metal hose, No. 5 solenoid valve, and long-term continuous electronic equipment. Step 5: Insulation and heat insulation of the pressure-resistant shell: When an underwater working platform is on the water surface, the continuous exposure to sunlight generally leads to a higher internal temperature of the pressure hull. However, underwater, the lower temperature of the surrounding seawater results in a lower internal temperature. The insulation and heat preservation methods for the pressure hull differ between the upper and lower semi-circular shells. When underwater, in the lower semi-circular shell, the cooling water in the conformal circulating water tank absorbs the heat released by the fuel cell stack and balances the heat conducted to the outside through the pressure hull, maintaining a suitable temperature. Therefore, the cooling water in the conformal circulating water tank acts as an insulation layer. In the upper semi-circular shell, a cylindrical vacuum insulation panel is used to cover the inside of the pressure hull for insulation. When on the water surface, the cooling water in the conformal circulating water tank acts as a heat insulation layer in the lower semi-circular shell, while the upper semi-circular shell is insulated using a cylindrical vacuum insulation panel.

[0014] The beneficial effects of this invention are as follows: This invention features a compact and rational structure and is easy to operate. By setting spiral heat exchange tube groups between the inner ribs, it makes full use of the space between the inner ribs and the arc section of the pressure hull, which are difficult to utilize. Heat transfer through the bulkhead avoids the need to introduce seawater into the hull to cool the system. This not only eliminates the equipment and piping of the traditional seawater cooling system and effectively reduces the power consumption of the auxiliary equipment, but also avoids the need for openings in the pressure hull for seawater pipes, effectively improving the structural safety of the underwater transport platform.

[0015] This invention automatically allocates and adjusts the number of spiral heat exchanger tubes based on the different cooling requirements of the fuel cell stack at different power levels, ensuring that the fuel cell stack is always within a suitable operating temperature range, effectively reducing heat loss and improving system efficiency.

[0016] This invention uses a conformal circulating water tank and a cylindrical vacuum insulation panel to insulate and heat the internal compartment space of the pressure-resistant shell, avoiding the traditional method of using air conditioning to regulate the compartment temperature. This not only reduces the number of devices and saves space, but also effectively reduces energy consumption.

[0017] In addition, the present invention also has the following advantages: 1. The spiral heat exchange tube assembly is arranged in the space between the inner ribs, thus eliminating the need for the traditional shell-and-tube heat exchanger. This not only increases the effective volume inside the chamber but also makes full use of the space between the inner ribs, which is usually difficult to utilize, effectively reducing the overall burden.

[0018] 2. By utilizing the heat transfer method of the pressure hull wall, the heat of the cooling water in the conformal circulating water tank is finally discharged to the outside of the pressure hull 1, avoiding the traditional method of drilling holes in the pressure hull to introduce seawater pipes into the cabin. Compared with the traditional cooling system, it not only eliminates the need for a seawater system, but also eliminates the need for perforation in the pressure hull, greatly improving the structural safety of the pressure hull.

[0019] 3. This system uses a temperature-controlled three-way valve. The solenoid valve can automatically allocate and adjust the number of spiral heat exchange tubes according to the different cooling requirements of the fuel cell stack at different power levels, ensuring that the stack is always within a suitable operating temperature range, effectively reducing heat loss and improving system efficiency.

[0020] 4. Taking advantage of the fluidity of cooling water, which can be placed in containers of any shape, a conformal circulating water tank with a shape similar to that of the pressure tank is set up. This not only absorbs the heat released by the fuel cell stack, but also makes effective use of the space in the pressure tank that is difficult to utilize.

[0021] 5. Installing external and internal ribs on the pressure hull not only increases the structural strength of the underwater working platform, but also increases the heat transfer area of ​​the pressure hull walls, thereby improving heat transfer efficiency.

[0022] 6. Using conformal circulating water tanks and cylindrical vacuum insulation panels for heat insulation of the internal compartments of the pressure hull avoids the traditional method of using air conditioning to regulate the compartment temperature, which not only saves equipment space but also effectively reduces power consumption.

[0023] 7. This system uses flexible metal hoses, which effectively prevents the pressure-resistant shell from deforming underwater due to water pressure and squeezing the pipeline, thus ensuring the safety of the pipeline. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the present invention.

[0025] Figure 2 for Figure 1Full sectional view along section AA.

[0026] Among them: 1. Pressure-resistant shell; 2. Conformal hot water exchange tank; 3. No. 2 metal flexible hose; 4. Solenoid valve No. 3; 5. Solenoid valve No. 1; 6. Solenoid valve No. 4; 7. Solenoid valve No. 2; 8. No. 3 metal flexible hose; 9. Inner ribs; 10. No. 3 spiral heat exchanger tube assembly; 11. No. 1 spiral heat exchanger tube assembly; 12. No. 4 metal flexible hose; 13. No. 1 metal flexible hose; 14. Fuel cell stack; 15. Solenoid valve No. 5; 16. Long-duration continuous electronic equipment; 17. Circulating water tank; 18. Circulating water pump; 19. Temperature-controlled three-way valve; 20. No. 2 spiral heat exchanger tube assembly; 21. No. 4 spiral heat exchanger tube assembly; 22. Outer ribs; 23. Lightweight outer shell; 24. Cylindrical vacuum insulation panel; 25. Drainage hole; 26. Return pipe No. 1; 27. Return pipe No. 2. Detailed Implementation

[0027] The specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0028] like Figures 1-2As shown, the fuel cell circulating water system for an underwater sealed chamber in this embodiment includes a pressure-resistant shell 1. A conformal heat exchange tank 2 is disposed inside the pressure-resistant shell 1. An annular space is formed between the inner wall of the pressure-resistant shell 1 and the outer wall of the conformal heat exchange tank 2. A cylindrical vacuum insulation plate 24 is installed in the upper half of this annular space, closely attached to the inner wall of the pressure-resistant shell 1. A first spiral heat exchange tube assembly 11 and a second spiral heat exchange tube assembly 20, symmetrically arranged on both sides, are installed in the lower half of this annular space. The system also includes a fuel cell fuel cell installed inside the pressure-resistant shell 1. Fuel cell stack 14, one end of which is connected in series with a circulating water tank 17, a circulating water pump 18 and a temperature-controlled three-way valve 19 via pipelines. One of the paths of the temperature-controlled three-way valve 19 is connected to the first spiral heat exchange tube group 11 via the first solenoid valve 5, and the other path is connected to the second spiral heat exchange tube group 20 via the second solenoid valve 7. The temperature-controlled three-way valve 19 is also connected to the fuel cell stack 14 via the first return pipe 26. The bottoms of the first spiral heat exchange tube group 11 and the second spiral heat exchange tube group 20 are connected by a connecting pipe. A second return pipe 27 is provided between the first return pipe 26 and the connecting pipe. The outer wall of the pressure-resistant shell 1 is welded with outer ribs 22 at intervals along the axial direction, and the inner wall of the pressure-resistant shell 1 is welded with inner ribs 9 at intervals along the axial direction. The inner ribs 9 correspond to the outer ribs 22. Each inner rib 9 has a hole in the middle. It also includes a No. 3 spiral heat exchange tube group 10 and a No. 4 spiral heat exchange tube group 21 symmetrically arranged in the lower half of the annular space. At the same time, the No. 3 spiral heat exchange tube group 10 and the No. 4 spiral heat exchange tube group 21 pass through the hole opened in the inner rib 9. The bottom of the No. 3 spiral heat exchange tube group 10 is connected to the connecting pipe through the No. 1 metal hose 13. The bottom of the No. 4 spiral heat exchange tube group 21 is connected to the connecting pipe through the No. 4 metal hose 12. One of the three-way temperature control valves 19 is also connected to the top of the No. 3 spiral heat exchange tube group 10 through the No. 3 solenoid valve 4 and the No. 2 metal hose 3, and the other is connected to the top of the No. 4 spiral heat exchange tube group 21 through the No. 4 solenoid valve 6 and the No. 3 metal hose 8. The pressure-resistant housing 1 is also provided with a lightweight outer shell 23.

[0029] The pressure hull 1 is a pressure-bearing sealed compartment capable of withstanding the back pressure of seawater, and the interior of the compartment is used to house system equipment.

[0030] The No. 1 spiral heat exchanger tube group 11, the No. 2 spiral heat exchanger tube group 20, the No. 3 spiral heat exchanger tube group 10 and the No. 4 spiral heat exchanger tube group 21 have the same structure, and all of them use a mixture of straight tubes and spiral heat exchanger tubes.

[0031] The straight sections of spiral heat exchanger tube group 10 (number three) and spiral heat exchanger tube group 21 (number four) pass through the openings in the inner rib 9.

[0032] Both outer rib 22 and inner rib 9 are made of ring rib plates.

[0033] The space between the pressure-resistant shell 1 and the lightweight outer shell 23 is filled with seawater.

[0034] The cylindrical vacuum insulation panel 24 uses environmentally friendly heat insulation materials.

[0035] The specific structure and function of the fuel cell circulating water system for an underwater sealed compartment according to the present invention are as follows: It mainly includes a pressure-resistant shell 1, a conformal heat exchange tank 2, multiple metal hoses, multiple solenoid valves, multiple sets of spiral heat exchange tubes, a temperature-controlled three-way valve 19, inner ribs 9, a fuel cell stack 14, a circulating water tank 17, long-term continuous electronic equipment 16, a circulating water pump 18, outer ribs 22, a cylindrical vacuum insulation panel 24, and a lightweight outer shell 23, etc.

[0036] This invention is mainly used to exchange the waste heat generated during the operation of the fuel cell stack 14 with the water in the conformal heat exchange tank 2 through the circulating water in the spiral heat exchange tube assembly. Part of the heat of the water in the conformal heat exchange tank 2 is transferred to the external seawater through the heat transfer of the pressure hull wall, and part of the waste heat is dissipated inside the cabin. The cabin temperature is maintained by the cylindrical vacuum insulation plate 24. In addition, the circulating water in the spiral heat exchange tube assembly, after being cooled by the water in the conformal heat exchange tank 2, can also be used to cool the long-term continuous electronic equipment 16.

[0037] The function of each component is explained in detail below: Pressure hull 1 — A pressure-bearing sealed compartment capable of withstanding the back pressure of seawater, the interior of which is used to house system equipment.

[0038] Conformal hot water tank 2—A hot water tank conformally to the pressure-resistant shell 1, in which the fresh water inside exchanges heat with the external seawater through the pressure-resistant shell 1.

[0039] Various metal hoses—a type of multi-layered flexible pipe with metal braiding layers, primarily used for transporting circulating water.

[0040] Each solenoid valve—a type of valve that can be controlled to open or close by being energized or de-energized—is used in this system to connect or disconnect corresponding pipelines.

[0041] Inner rib 9—A type of annular rib welded axially at regular intervals inside a pressure-resistant shell.

[0042] Spiral heat exchanger tube assembly—a type of heat exchanger tube that uses a combination of straight and spiral tubes.

[0043] Fuel cell stack 14—A power generation device that uses hydrogen as fuel and oxygen as oxidant to convert chemical energy into electrical energy through an electrochemical reaction.

[0044] Long-duration continuous electronic device 16 — An electronic device that operates continuously for a long time and generates a certain amount of heat during normal operation.

[0045] Circulating water tank 17—a type of tank placed at the front end of the circulating water pump to prevent the circulating water pump from running dry and to maintain the stability of the system's circulating water pressure.

[0046] Circulating water pump 18—A water pump used to provide head for pipelines, and this system is used to provide water pressure for circulating water pipelines.

[0047] Thermostatic three-way valve 19—a valve with three pipe connections, which may have one inlet and two outlets or two inlets and one outlet.

[0048] Outer rib 22—an annular rib plate welded axially at certain intervals to the outside of the pressure shell 1.

[0049] Lightweight hull 23—a hull for maintaining the external profile of an underwater platform, with a pressure hull 1 inside it, and the space between the pressure hull 1 and the pressure hull 1 filled with seawater.

[0050] Cylindrical vacuum insulation panel 24—an environmentally friendly heat insulation material with good heat insulation performance. It is mainly composed of core material, getter and high barrier film. The core material plays a supporting and heat insulation role, the high barrier film mainly forms a closed vacuum space, and the getter is mainly used to absorb the gas entering the high barrier film to maintain its low vacuum degree.

[0051] Water flow hole 25—a small hole in the lower part of the annular inner rib 9 for water to flow between the various inner ribs 9.

[0052] The main function of this invention is to exchange the waste heat generated during the operation of the fuel cell stack with water in a conformal heat exchange tank via circulating water in a spiral heat exchange tube assembly. Part of the heat from the water in the conformal heat exchange tank is transferred to the external seawater through the pressure hull walls, while some of the waste heat is dissipated within the cabin, and the cabin temperature is maintained by cylindrical vacuum insulation panels. Furthermore, the circulating water in the spiral heat exchange tube assembly, cooled by the water in the conformal heat exchange tank, can also be used to cool long-term continuous electronic equipment. By installing spiral heat exchange tube assemblies between the inner ribs, the invention fully utilizes the space between the inner ribs and the unusable space of the curved section of the pressure hull. Heat transfer through the hull walls avoids introducing seawater into the cabin for system cooling, eliminating the need for equipment and piping in traditional seawater cooling systems, effectively reducing auxiliary power consumption, and avoiding openings in the pressure hull for seawater piping, thus significantly improving the structural safety of the underwater working platform. Furthermore, the number of spiral heat exchanger tubes is automatically allocated and adjusted according to the different cooling requirements of the fuel cell stack at different power levels, ensuring that the fuel cell stack is always within a suitable operating temperature range, effectively reducing heat loss and improving system efficiency. The use of conformal circulating water tanks and cylindrical vacuum insulation panels for the insulation and heat preservation of the internal compartments of the pressure hull avoids the traditional method of using air conditioning to regulate the compartment temperature, which not only reduces the number of equipment and saves equipment space, but also effectively reduces energy consumption.

[0053] In actual work process: (a) Automatic distribution and regulation of heat dissipation in fuel cell stack circulating water cooling system: When the fuel cell stack undergoes a cold start, the circulating water inside the stack is at a low temperature and is being heated by the stack. Therefore, it does not require further cooling via the spiral heat exchanger tube assembly. The circulating water then returns to the fuel cell stack 14 via the circulating water tank 17, circulating water pump 18, and temperature-controlled three-way valve 19. When the fuel cell stack 14 continues to operate and requires cooling, the circulating water then flows through the circulating water tank 17, circulating water pump 18, temperature-controlled three-way valve 19, solenoid valve 5, and spiral heat exchanger tube assembly 1. 1. Returning to the fuel cell stack 14; when the power of the fuel cell stack continuously increases, and a single set of spiral heat exchange tubes cannot meet the cooling requirements of the stack, the number of spiral heat exchange tubes is increased by controlling solenoid valves 4, 6, and 7 to ensure continuous cooling of the stack; conversely, when the power of the fuel cell stack decreases, the number of spiral heat exchange tubes is reduced by controlling the solenoid valves. In this way, the circulating water of the stack is automatically distributed and adjusted by controlling the number of spiral heat exchange tubes through the temperature-controlled three-way valve 19, thereby reducing heat loss and improving system efficiency.

[0054] (ii) Effectively utilize the space within the inner ribs to achieve heat exchange through spiral heat exchange tube assemblies: Multiple sets of spiral heat exchange tubes are connected by multiple spiral heat exchange tubes arranged in the space between the inner ribs 9. When the fuel cell stack 14 needs to be loaded or run at high power continuously, the circulating water flowing through the spiral heat exchange tube sets 10, 11, 20, and 21 is at a high temperature and needs to be cooled to ensure that the stack continues to work in the best condition. Therefore, the cooling water in the conformal circulating water tank 2 is needed to exchange heat and cool it, ensuring that the heat in the stack's circulating water is carried away by the cooling water in the conformal circulating water tank 2 in a timely manner.

[0055] (III) Heat transfer through the pressure hull walls: As the heat from the circulating water in the multiple sets of spiral heat exchanger tubes is continuously exchanged with the cooling water in the conformal circulating water tank 2, the temperature of the cooling water in the conformal circulating water tank 2 will gradually increase. When it rises to a certain value (20 to 30 degrees Celsius), there will be a temperature difference of about 20 degrees Celsius between the cooling water in the conformal circulating water tank 2 and the seawater between the pressure hull 1 and the lightweight outer shell 23. This allows the heat from the cooling water in the conformal circulating water tank 2 to be ultimately discharged to the outside of the pressure hull 1 through heat transfer via the walls of the pressure hull 1. The outer ribs 22 and inner ribs 9 on the pressure hull 1, in addition to increasing the structural strength of the underwater working platform, also increase the heat transfer area of ​​the pressure hull 1 walls, thus improving heat transfer efficiency.

[0056] (iv) Long-term continuous cooling of electronic equipment: When the long-term continuous electronic equipment is working normally, it will also emit a certain amount of heat. At this time, the circulating water in the circulating water tank 17 will return to the circulating water tank 17 through the circulating water pump 18, the temperature control three-way valve 19, the first solenoid valve 5 or the second solenoid valve 4, the spiral heat exchange tube group 20 or 21, the metal hose 13, the solenoid valve 15, and the long-term continuous electronic equipment 16.

[0057] (v) Thermal insulation of the pressure-resistant shell 1: When the underwater working platform is on the water surface, the internal temperature of the pressure hull 1 is generally high due to continuous sunlight. However, when underwater, the external seawater temperature is lower, resulting in a lower internal temperature for the pressure hull 1. The insulation and heat preservation methods for the pressure hull 1 differ between the upper and lower semi-circular shells. When underwater, in the lower semi-circular shell, the cooling water in the conformal circulating water tank 2 absorbs the heat released by the fuel cell stack and balances the heat conducted to the outside through the pressure hull 1, maintaining a suitable temperature. Therefore, the cooling water in the conformal circulating water tank 2 acts as an insulation layer. In the upper semi-circular shell, a cylindrical vacuum insulation panel 24 is used to cover the inside of the pressure hull 1, providing insulation. When on the water surface, the cooling water in the conformal circulating water tank 2 acts as a heat insulation layer in the lower semi-circular shell, while the upper semi-circular shell is insulated using the cylindrical vacuum insulation panel 24.

[0058] The above description is an explanation of the present invention and not a limitation thereof. The scope of the present invention is defined by the claims. Within the scope of protection of the present invention, any form of modification may be made.

Claims

1. A fuel cell circulating water system for an underwater sealed compartment, characterized in that: The system includes a pressure-resistant housing (1), inside which a conformal heat exchange tank (2) is installed. An annular space is formed between the inner wall of the pressure-resistant housing (1) and the outer wall of the conformal heat exchange tank (2). A cylindrical vacuum insulation plate (24) is installed in the upper half of this annular space, and the cylindrical vacuum insulation plate (24) is in close contact with the inner wall of the pressure-resistant housing (1). A first spiral heat exchange tube assembly (11) and a second spiral heat exchange tube assembly (20) are installed in the lower half of this annular space. The system also includes a fuel cell stack (14) installed inside the pressure-resistant housing (1). The end is connected in series with a circulating water tank (17), a circulating water pump (18) and a temperature control three-way valve (19) through pipelines. One of the paths of the temperature control three-way valve (19) is connected to the first spiral heat exchange tube group (11) through the first solenoid valve (5), and the other path is connected to the second spiral heat exchange tube group (20) through the second solenoid valve (7). The temperature control three-way valve (19) is also connected to the fuel cell stack (14) through the first return pipe (26). The bottoms of the first spiral heat exchange tube group (11) and the second spiral heat exchange tube group (20) are connected by a connecting pipe. A second return pipe (27) is provided between the first return pipe (26) and the connecting pipe. The outer wall of the pressure-resistant shell (1) is welded with outer ribs (22) at intervals along the axial direction, and the inner wall of the pressure-resistant shell (1) is welded with inner ribs (9) at intervals along the axial direction. The inner ribs (9) correspond to the outer ribs (22). Each inner rib (9) has a hole in the middle. It also includes a No. 3 spiral heat exchange tube group (10) and a No. 4 spiral heat exchange tube group (21) symmetrically arranged in the lower half of the annular space. At the same time, the No. 3 spiral heat exchange tube group (10) and the No. 4 spiral heat exchange tube group (21) pass through the inner ribs ( 9) The bottom of the No. 3 spiral heat exchanger tube group (10) is connected to the connecting pipe through the No. 1 metal hose (13), and the bottom of the No. 4 spiral heat exchanger tube group (21) is connected to the connecting pipe through the No. 4 metal hose (12). One of the paths of the temperature control three-way valve (19) is also connected to the top of the No. 3 spiral heat exchanger tube group (10) through the No. 3 solenoid valve (4) and the No. 2 metal hose (3), and the other path is connected to the top of the No. 4 spiral heat exchanger tube group (21) through the No. 4 solenoid valve (6) and the No. 3 metal hose (8). The pressure-resistant housing (1) is also provided with a lightweight outer shell (23).

2. The fuel cell circulating water system for an underwater sealed compartment as described in claim 1, characterized in that: The pressure-resistant shell (1) is a pressure-bearing sealed chamber that can withstand the back pressure of seawater, and the interior of the chamber is used to house system equipment.

3. A fuel cell circulating water system for an underwater sealed compartment as described in claim 1, characterized in that: The No. 1 spiral heat exchanger tube group (11), the No. 2 spiral heat exchanger tube group (20), the No. 3 spiral heat exchanger tube group (10) and the No. 4 spiral heat exchanger tube group (21) have the same structure and all use a mixture of straight tubes and spiral heat exchanger tubes.

4. A fuel cell circulating water system for an underwater sealed compartment as described in claim 3, characterized in that: The straight sections of the No. 3 spiral heat exchanger tube group (10) and the No. 4 spiral heat exchanger tube group (21) pass through the openings in the inner rib (9).

5. A fuel cell circulating water system for an underwater sealed compartment as described in claim 1, characterized in that: Both the outer rib (22) and the inner rib (9) are made of annular rib plates.

6. A fuel cell circulating water system for an underwater sealed compartment as described in claim 1, characterized in that: The pressure-resistant shell (1) and the lightweight shell (23) are filled with seawater.

7. A fuel cell circulating water system for an underwater sealed compartment as described in claim 1, characterized in that: The cylindrical vacuum insulation panel (24) uses environmentally friendly heat insulation materials.

8. An operation process of a fuel cell circulating water system for an underwater sealed compartment as described in claim 1, characterized in that: The following steps are included: Step 1: Automatic distribution and adjustment of heat dissipation in fuel cell stack circulating water cooling system: When the fuel cell stack (14) is cold-started, the circulating water inside the stack is at a low temperature and is being heated by the stack. Therefore, it does not need to be cooled again through the spiral heat exchanger tube assembly. The circulating water inside the stack returns to the fuel cell stack (14) through the circulating water tank (17), the circulating water pump (18), and the temperature-controlled three-way valve (19). When the fuel cell stack (14) continues to work and needs to be cooled, the circulating water inside the stack passes through the circulating water tank (17), the circulating water pump (18), the temperature-controlled three-way valve (19), the first solenoid valve (5), and the first solenoid valve (19). The spiral heat exchange tube group (11) returns to the fuel cell stack (14). When the power of the fuel cell stack (14) increases and a single spiral heat exchange tube group cannot meet the cooling requirements of the stack, the number of spiral heat exchange tube groups is increased by controlling the second solenoid valve (7), the third solenoid valve (4), and the fourth solenoid valve (6) to ensure continuous cooling of the stack. Conversely, when the power of the fuel cell stack (14) decreases, the number of spiral heat exchange tube groups is reduced by controlling the solenoid valves. In this way, the circulating water of the stack is automatically distributed and adjusted by controlling the number of spiral heat exchange tube groups through the temperature control three-way valve (19). Step 2: Effectively utilize the space within the inner ribs to achieve heat exchange via spiral heat exchange tube assemblies: When the fuel cell stack (14) needs to be loaded or run at high power continuously, the temperature of the circulating water flowing through all the spiral heat exchange tube groups is high and needs to be cooled to ensure that the stack continues to work in the best state. Therefore, the cooling water in the conformal heat exchange tank (2) is needed to exchange heat and cool it to ensure that the heat in the stack circulating water is carried away by the cooling water in the conformal heat exchange tank (2) in time. Step 3: Heat transfer through the pressure hull walls: When the heat of the circulating water in the multiple sets of spiral heat exchange tubes is continuously exchanged with the cooling water in the conformal heat exchange tank (2), the temperature of the cooling water in the conformal heat exchange tank (2) will gradually increase. When it rises to 20 to 30 degrees Celsius, there is a temperature difference between the cooling water in the conformal heat exchange tank (2) and the seawater between the pressure hull (1) and the light outer shell (23). In this way, the heat of the cooling water in the conformal heat exchange tank (2) will be finally discharged to the outside of the pressure hull (1) through the heat transfer of the bulkhead of the pressure hull (1). Step 4: Long-term continuous cooling of electronic equipment: When the long-term continuous electronic equipment is working normally, it will also emit a certain amount of heat. At this time, the circulating water in the circulating water tank (17) will return to the circulating water tank (17) through the circulating water pump (18), temperature control three-way valve (19), solenoid valve, spiral heat exchange tube group, metal hose, No. 5 solenoid valve (15), and long-term continuous electronic equipment (16). Step 5: Pressure-resistant shell (1) Thermal insulation: When the underwater working platform is on the water surface, the temperature inside the pressure shell (1) is high due to continuous exposure to the sun. When it is underwater, the temperature inside the pressure shell (1) is also low due to the lower temperature of the seawater outside. The heat insulation and heat insulation methods of the pressure shell (1) are different in the upper and lower semi-circular shells. When it is underwater, in the lower semi-circular shell, the cooling water in the conformal heat exchange tank (2) absorbs the heat released by the electric stack and the heat conducted to the outside through the pressure shell (1) reaches a balance, and maintains a suitable temperature. Therefore, the cooling water in the conformal heat exchange tank (2) acts as a heat insulation layer. In the upper semi-circular shell, a cylindrical vacuum insulation plate (24) is used to cover the inside of the pressure shell (1) to play a heat insulation role. When it is on the water surface, in the lower semi-circular shell, the cooling water in the conformal heat exchange tank (2) acts as a heat insulation layer. In the upper semi-circular shell, a cylindrical vacuum insulation plate (24) is used for heat insulation.

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