Underwater compact delta arrangement of thermoelectric isotopic power supply

Abstract

The application belongs to the technical field of isotope power supply, and discloses an underwater compact triangular arrangement temperature difference thermoelectric isotope power supply, which comprises a pressure-bearing shell system, a power generation stack and a heat management system, the power generation stack is formed by coaxially stacking a plurality of single-layer power generation modules in the vertical direction, the single-layer power generation module comprises a graphite base and a stainless steel shell layer sleeved outside the graphite base, a fuel pellet is arranged in the graphite base, the graphite base has a main heat transfer surface, a recessed groove platform is arranged at a position corresponding to the main heat transfer surface of the stainless steel shell layer, and a temperature difference power generation device is attached to the recessed groove platform. The isotope power supply overcomes the key technical bottlenecks of the conventional underwater isotope power supply, such as loose structure, low heat management efficiency, poor environmental adaptability and the like, and realizes breakthroughs in the comprehensive performance of the power supply system, such as volume energy density, thermoelectric conversion efficiency, passive heat dissipation capacity and full-cycle reliability.

Description

Technical Field

[0001] This application belongs to the field of isotope power source technology, and particularly relates to an underwater compact triangular arrangement thermoelectric isotope power source. Background Technology

[0002] The deep sea covers over 90% of the Earth's surface, serving as a treasure trove of resources and a climate regulator. Long-term, in-situ, and detailed observation and exploration of the deep sea are core capabilities crucial for scientific research, resource exploration, and national security. However, the realization of this ambitious goal is consistently constrained by a fundamental and severe challenge—a stable, sustainable, and high-energy-density self-sufficient energy supply. Current mainstream underwater propulsion systems all exhibit inherent and insurmountable flaws when faced with the extreme demand of "no maintenance or resupply required for years or even decades."

[0003] Currently, high-energy-density lithium-ion batteries are the preferred power source for most underwater observation nodes due to their mature technology, high instantaneous power, and noiselessness. However, their physicochemical nature limits their application in ultra-long-duration missions. First, there is a theoretical ceiling to energy density. Even the most advanced solid-state lithium batteries struggle to exceed 500 Wh / kg in specific energy. This means that the weight and volume of batteries required to support a year-long mission would be extremely large, severely encroaching on the space of sensors, robotic arms, and other payloads, and even compromising the mobility and economic viability of the carrier itself. Second, cycle life and deep discharge are mutually exclusive. Deep discharge, undertaken to achieve longer endurance, drastically accelerates the degradation of the battery's internal electrode materials, leading to a sharp decrease in capacity. Conversely, shallow charging and discharging to protect the battery significantly reduces the actual usable energy. More importantly, battery power is essentially a "stock consumption" process. Once depleted, it must be recovered and recharged by a surface mother ship or base. This not only generates high operating costs and complex logistical dependencies but also makes long-term, continuous observation in remote waters or under ice a distant dream. Therefore, chemical battery solutions are only suitable for short-cycle, highly mobile missions and cannot serve as a "baseline power source" for long-term deep-sea deployments.

[0004] Hydrogen-oxygen reaction-based fuel cells offer a path to continuous power generation through "fuel consumption," with a theoretical energy density higher than that of batteries. However, the complexity of this system casts a shadow over its underwater applications. The system must simultaneously and safely store high-pressure hydrogen and oxygen (or extract them from seawater) and is equipped with sophisticated reactant delivery, water management, and waste heat removal subsystems. Each link increases the probability of failure and reduces overall reliability. In the high-pressure, corrosive, and biofouling environment of the deep sea, the risks of catalyst performance degradation, membrane electrode fouling, or reactant pipeline leakage are dramatically amplified. Furthermore, the relatively constant power output of fuel cells makes it difficult to efficiently match the changing workloads of underwater equipment, resulting in insufficient dynamic response capabilities. Although their range is superior to batteries, it is still limited by the total amount of fuel carried, and regular refueling also presents significant logistical challenges. Essentially, fuel cells are a "modified consumable" power source, failing to fundamentally eliminate dependence on logistical resupply, and their system complexity inherently conflicts with the "simplicity and reliability" principles required by the extreme environment of the deep sea.

[0005] Radioisotope thermoelectric generators (RTGs) utilize the stable heat generated by the decay of radioactive isotopes such as plutonium-238, directly converting it into electrical energy through thermoelectric materials. With a lifespan of decades, no need for air, and strong environmental adaptability, they are a classic energy source for deep space exploration (such as the Voyager and Curiosity Mars rovers). However, when transitioning from the vacuum environment of space to the high-pressure, corrosive, and thermally conductive environment of the deep sea, traditional RTG design paradigms face severe challenges, as follows: First, space utilization is low and the structure is bulky. Traditional RTGs often adopt a cylindrical layout with a cylindrical heat source block surrounding a ring-shaped thermopile, or a simple flat plate docking structure. This layout creates a large amount of unused space within the deep-sea pressure hull, resulting in low overall volumetric power density. To withstand hydrostatic pressures of tens of megapascals, they have to rely on a heavy cylindrical pressure hull, leading to a huge system mass and an unsatisfactory effective energy ratio (output power / total mass).

[0006] Secondly, the thermal management design failed to be deeply integrated with the characteristics of the deep sea. Seawater is an excellent cooling medium, but the heat dissipation path in traditional layouts is often unbalanced. The low thermoelectric fill rate of traditional designs leads to a low overall heat flux density and thus a low conversion efficiency. The three functions of heat removal, structural pressure bearing, and shell corrosion protection are handled by different components, lacking an integrated design, resulting in system redundancy and bloat.

[0007] In summary, current underwater energy technology faces a clear divide: chemical batteries and fuel cells cannot meet the transformative demands for "ultra-long standby time and maintenance-free operation"; while traditional isotope power sources, which should be capable of this, are ill-suited to the environment due to their loose structure, inefficient thermal management, and incompatibility with the environment. Their enormous potential is constrained by their cumbersome physical form and suboptimal system design. Deep-sea equipment urgently needs a "structural revolution" in its energy systems, requiring a completely new design solution that deeply and ingeniously integrates the long-life nature of isotopes with the special constraints of the deep-sea environment (high pressure, corrosion, and efficient heat dissipation) and the stringent space limitations of the carrier platform. Summary of the Invention

[0008] The purpose of this application is to overcome the shortcomings of the prior art and provide an underwater compact triangular arrangement thermoelectric isotope power source. This isotope power source is a new type of isotope thermoelectric power source that is suitable for extreme deep-sea environments and has both ultra-long endurance and high stealth.

[0009] To achieve the above objectives, this application provides the following technical solution: This application provides an underwater compact triangular arrangement thermoelectric isotope power source, comprising: The pressure-bearing shell system constitutes the main pressure boundary of the power source; The power generation stack, located inside the pressure-bearing shell system, is composed of several single-layer power generation modules stacked coaxially in the vertical direction; A thermal management system is used to convert the heat energy generated by the decay of radioactive isotopes into electrical energy and to remove waste heat to the external seawater. The single-layer power generation module includes a graphite substrate and a stainless steel shell sleeved on the outside of the graphite substrate. A fuel pellet is disposed inside the graphite substrate. The graphite substrate has a main heat transfer surface. A recessed groove platform is provided at the position corresponding to the main heat transfer surface on the stainless steel shell. The thermoelectric generator is attached to the groove platform.

[0010] As one feasible approach, the pressure-bearing shell system adopts an integrated welded structure, including a main pressure-bearing cylinder, a lower head, and an upper head; The lower end cap is a fixed hemispherical structure, which is welded to the bottom of the main pressure-bearing cylinder by a circumferential weld. The upper end cap is a detachable structure, with its flange face abutting against the flange face at the top of the main pressure-bearing cylinder. A metal sealing ring is provided between the mating surfaces, and after installation and commissioning, the upper end cap is welded and sealed to the main pressure-bearing cylinder by a final circumferential weld.

[0011] As one feasible approach, three support legs evenly distributed at 120° are welded below the lower end cap to form a tripod support structure, and each support leg is provided with a ball joint at its bottom.

[0012] As one feasible approach, the single-layer power generation module adopts a multi-layer stacked integrated structure, and two adjacent single-layer power generation modules are connected by a positioning structure. The lower surface of the upper single-layer power generation module has a boss at its center, and the upper surface of the lower single-layer power generation module has a corresponding recess. The boss is embedded in the recess to form a self-centering structure.

[0013] As one feasible approach, the height of the boss is 2-3 mm, the depth of the recess is 2-3 mm, and the electrical connection between the single-layer power generation modules adopts flexible jumper wires.

[0014] As an feasible approach, flexible graphite thermal pads are also provided between the adjacent single-layer power generation modules.

[0015] As one possible implementation, the thermal management system includes a cold-end heat dissipation assembly, which includes a stainless steel pressure plate, a nano-aerogel insulation layer, heat dissipation fins, and a preload spring assembly. The stainless steel pressure plate is connected to the cold end of the thermoelectric generator; The heat dissipation fins are welded to the outer surface of the main pressure-bearing cylinder; The preload spring assembly is installed between the stainless steel shell and the stainless steel pressure plate to provide continuous clamping force.

[0016] As one possible implementation, the heat dissipation fins are longitudinally arranged titanium alloy fins, and the nano-aerogel insulation layer is filled between the non-heat-transfer surface of the stainless steel shell and the stainless steel pressure plate.

[0017] As one feasible approach, the graphite matrix has an equilateral triangular cross-section, with a fuel pellet embedded at each of its three vertices, forming a triangularly symmetrical heat source distribution, and the three sides of the graphite matrix serve as the main heat transfer surfaces.

[0018] As one possible implementation, the power supply also includes an auxiliary system, which includes a bottom insulation system and an equipment compartment; The bottom insulation system is disposed between the bottom of the power generation stack and the lower end cap; The equipment compartment is located on top of the power generation stack and houses the power management unit, monitoring subsystem, and output transmission interface.

[0019] As one feasible approach, the power supply has a three-level safety protection structure: The first level of protection is the double-layer encapsulation and sealing structure of the fuel pellet itself; The second level of protection is the independent sealing structure of the single-layer power generation module, including the seal between the graphite substrate and the stainless steel shell. The third level of protection is the integrated welded sealing structure of the pressure-bearing shell system.

[0020] As one feasible approach, the fuel pellets are plutonium dioxide fuel pellets; the graphite matrix is ​​made of high-purity graphite material.

[0021] As one possible implementation, the thermoelectric device comprises a Bi2Te3-PbTe thermocouple.

[0022] As an feasible approach, both the main pressure-bearing cylinder and the supporting leg are made of titanium alloy.

[0023] Compared with the prior art, the underwater compact triangular arrangement thermoelectric isotope power source provided in this application has the following advantages: This application provides a high-energy-density, long-life, maintenance-free autonomous power supply system suitable for deep-sea long-term operation platforms, seabed observation network nodes, and other equipment. Its core objective is to overcome the key technical bottlenecks of traditional underwater isotope power sources, such as loose structure, low thermal management efficiency, and poor environmental adaptability, through an innovative triangular arrangement of heat sources and a modular stacked structure design. This achieves breakthroughs in the comprehensive performance of the power system, including volumetric energy density, thermoelectric conversion efficiency, passive heat dissipation capability, and full-cycle reliability. Therefore, it provides a compact, silent, maintenance-free, and environmentally adaptable long-term power solution for deep-sea long-term unmanned operation platforms. The structure and power of this application can be reasonably adjusted according to the specific application scenarios and can be used in various similar isotope power systems.

[0024] This application achieves extreme compactness and high energy density output of the system in extreme deep-sea environments through an innovative triangular arrangement of heat sources and a multi-layer modular stacking design. This structure integrates the isotope heat source, thermoelectric conversion unit, and passive cooling system in a three-dimensional space of only 0.3 meters in diameter and 0.5 meters in height, achieving a volumetric power density more than twice that of traditional columnar isotope power sources. This provides a core power source for long-term operation on space-constrained platforms such as miniaturized deep-sea submersibles and portable observation nodes.

[0025] The power system of this application is based on the principle of static thermoelectric conversion. During operation, there are no moving parts, no fluid circulation pumping, and no chemical reaction. It has the characteristics of low noise and zero emission. Its underwater radiated noise is lower than the background noise of the marine environment, which can be perfectly integrated into the quiet working environment. It is particularly suitable for underwater acoustic monitoring, covert observation and acoustically sensitive scientific research tasks, and will not cause chemical or thermal pollution to the surrounding marine ecological environment.

[0026] This application establishes a complete defense-in-depth security system through a three-level protection design of multiple fuel pellet encapsulation, independent module sealing, and main pressure-bearing shell.

[0027] Furthermore, the triangular thermal diffusion and three-sided thermoelectric conversion configuration based on a graphite matrix provided in this application, combined with the strong natural convection heat dissipation induced by six layers stacked at optimal height, constructs a highly efficient and stable thermoelectric energy conversion channel. This design allows decay heat to be directionally and uniformly introduced into the thermoelectric conversion interface, while enhancing the passive heat exchange capacity of seawater through a vertical direct current channel. The system can achieve a net conversion efficiency of 7-10% under an operating temperature difference of 320-340℃, and the long-term power output stability is better than ±3%, significantly improving the energy utilization efficiency of static thermoelectric systems in deep-sea environments.

[0028] Furthermore, this application employs an architecture that separates the integrated welded titanium alloy pressure-bearing shell from the internal modular functional stack. This significantly improves the system's manufacturability, testability, and maintainability while ensuring absolute reliability at the pressure boundary. The integrated shell eliminates the risk of dynamic sealing and achieves permanent sealing through full-penetration welding. The internal stack supports independent assembly, testing, and rapid replacement, reducing the system's total life-cycle maintenance costs by more than 70% and providing the capability for field-level maintenance under dedicated support conditions.

[0029] Furthermore, this application, based on a standardized single-layer module interface, supports flexible power output configuration and continuous upgrades to the technical configuration. By adding or removing stacking layers, the output power can be adjusted within the range of 50~300W to adapt to different task requirements; the thermoelectric conversion module adopts a pluggable interface design, which facilitates the replacement of more efficient thermoelectric materials in the future, enabling the system to continuously absorb technological advancements and maintain long-term performance competitiveness.

[0030] Furthermore, the isotope power source adopts a modular, layered design, forming three distinct structural layers from the outside in. This layered design decouples the pressure boundary from the power generation function, ensuring structural reliability in deep-sea environments while facilitating standardized manufacturing and maintenance of internal functional modules. All structural components are arranged axially symmetrically to ensure uniform stress distribution under high-pressure deep-sea conditions, while also facilitating machining, assembly, and quality control.

[0031] Furthermore, the upper surface of the single-layer module has a 2-3mm protrusion in the middle, and the graphite matrix part in the middle of the lower surface is recessed by 2-3mm to facilitate the stacking of different modules. Flexible thermal pads are set between the layers to ensure effective heat conduction between the layers and to compensate for dimensional changes caused by thermal expansion.

[0032] Furthermore, the outer layer of the titanium alloy sleeve is welded with fins with a rib height of 4cm to enhance heat exchange and ensure that the heat from the cold surface of the thermoelectric device can be completely dissipated. In addition, a pre-tightening spring is installed between the stainless steel shell and the stainless steel pressure plate to ensure that the thermoelectric device does not shift under temperature difference in environments such as ocean currents, while avoiding incomplete contact between the pressure plate and the cold surface of the thermoelectric device under thermal stress. Attached Figure Description

[0033] To more clearly illustrate the technical solution of this application, the accompanying drawings used in the technical description will be briefly introduced below.

[0034] Figure 1 A schematic axial cross-sectional view of the underwater compact triangular thermoelectric isotope power source provided in this application; Figure 2 A cross-sectional schematic diagram of the underwater compact triangular thermoelectric isotope power source provided in this application; Figure 3 An axial front view of the single-layer graphite matrix and stainless steel shell provided in this application.

[0035] Explanation of reference numerals in the attached figures: 101-Main pressure-bearing cylinder; 102-Lower head; 103-Upper head; 104-Circumferential weld; 105-Flange connection face; 106-Metal sealing ring; 107-Final circumferential weld; 108-Support leg; 109-Integrated hoisting interface; 201-Graphite matrix; 202-Plutonium dioxide fuel pellet; 203-Main heat transfer surface; 204-Circular arc transition structure; 205-Stainless steel shell; 206-Groove platform; 207-Thermoelectric device; 301 - Upper boss positioning structure; 302 - Lower recess positioning structure; 303 - Flexible graphite thermal conductive pad; 401 - Stainless steel pressure plate; 402 - Nano aerogel insulation layer; 403 - Heat dissipation fins; 404 - Preloaded spring assembly; 501 - Bottom insulation system; 502 - Equipment compartment; 503 - Power management unit; 504 - Monitoring subsystem; 505 - Output transmission interface. Detailed Implementation

[0036] The following detailed description provides further details on specific implementation methods.

[0037] like Figures 1 to 3 As shown, this application provides an underwater compact triangular arrangement thermoelectric isotope power source, including a pressure-bearing shell system, several single-layer power generation modules, an auxiliary system, a thermal management system, and a safety protection system.

[0038] The pressure-bearing shell system forms the main pressure boundary of the power source. It adopts an integrated welded structure to resist the high-pressure environment of the deep sea, while providing an installation foundation and mechanical protection for the internal systems. It also achieves seabed stability through bottom support legs.

[0039] The single-layer power generation module is used to directly convert the heat energy generated by the decay of radioactive isotopes into electrical energy. Each module adopts a heat source and thermoelectric conversion device arranged in a triangular symmetry, and achieves large-scale power output through multi-layer stacking.

[0040] The auxiliary system provides support for the reliable operation of the power supply, including bottom insulation to reduce heat loss, a top equipment compartment to house the power management and monitoring unit, and an annular gap to optimize the heat conduction path.

[0041] The thermal management system is used to achieve passive and efficient removal of waste heat. It stimulates natural convection of seawater through multi-layer stacking and enhances heat exchange with fins to ensure that the thermoelectric conversion device operates under optimal temperature difference conditions.

[0042] The safety protection system is used to establish a multi-layered radioactive safety barrier, including a three-level protection system consisting of double-layer cladding of fuel pellets, independent sealing of modules, and an integrated pressure-bearing shell, to ensure the safety of long-term deep-sea operation.

[0043] like Figure 1 As shown, the isotope power source adopts a vertical cylindrical configuration with a highly compact overall structure. The diameter-to-height ratio has been optimized to adapt to the limited installation space of deep-sea equipment, and it has excellent hydrodynamic characteristics.

[0044] This isotope power source adopts a modular, layered design, forming three distinct structural layers from the outside in: the outermost layer is a pressure-bearing and sealing layer, consisting of an integrated welded main pressure-bearing cylinder 101 and heat dissipation fins 403; the middle layer is a thermoelectric conversion layer, composed of six identical single-layer power generation modules stacked vertically, with each module containing three thermoelectric generators 207; and the isotope core layer consists of plutonium dioxide fuel pellets 202 and a graphite matrix 201. This layered, decoupled design ensures structural integrity under the high-pressure environment of the deep sea while also enabling the replaceability and maintainability of the power generation units.

[0045] Specifically, the pressure-bearing shell system constitutes the main pressure boundary of the power supply and adopts an integrated welded structure design. For example... Figure 1 As shown, the pressure-bearing shell system includes a main pressure-bearing cylinder 101, a lower end cap 102, and an upper end cap 103. All connecting parts are welded using a full penetration welding process to form a continuous and complete sealing structure.

[0046] The lower end cap 102 is a fixed hemispherical structure, which is permanently welded to the main pressure-bearing cylinder 101 through the circumferential weld 104 to form a non-removable power base, constituting the bottom sealing end of the isotope power source.

[0047] Three support legs 108 are welded at 120° to the bottom of the lower head 102, forming a stable tripod support structure. Each support leg 108 has a ball joint at the bottom to adapt to uneven seabed topography and ensure the stability of the power supply on complex seabed topography.

[0048] The upper head 103 adopts a detachable design, with its flange face 105 mating with the flange face at the top of the main pressure-bearing cylinder 101. A metal sealing ring 106 is provided between the mating surfaces as a detachable seal. After the internal components are installed and commissioned, the upper head 103 is welded and sealed by the final circumferential weld 107.

[0049] The top of the upper head 103 is equipped with an integrated lifting interface 109, including lifting lugs and guide rings. The integrated lifting interface 109 adopts a double-sided symmetrical arrangement: two lifting lugs are welded to the two sides of the top of the upper head 103 respectively, and are used to connect the lifting cables to achieve lifting; the guide ring is fixedly connected to the root of the lifting lugs or the upper head 103 through evenly distributed stiffening plates, and cooperates with the guiding mechanism during deployment to ensure stable positioning of the power supply and meet the requirements of deep-sea deployment and recovery operations.

[0050] Preferably, the main pressure-bearing cylinder 101 is made of titanium alloy material, and the main pressure-bearing cylinder 101 is a main pressure-bearing titanium alloy cylinder.

[0051] Preferably, the metal sealing ring 106 is a metal C-shaped sealing ring.

[0052] Preferably, the support leg 108 is made of titanium alloy, and the support leg 108 is a titanium alloy support leg.

[0053] like Figure 2 As shown, the single-layer power generation module includes a graphite substrate 201, a fuel pellet 202, a main heat transfer surface 203, an arc transition structure 204, a stainless steel shell 205, and a thermoelectric power generation device 207.

[0054] The single-layer power generation module is the basic functional unit of the power supply. It adopts an equilateral triangular shape, facilitating compact arrangement within the main pressure-bearing cylinder 101 and maximizing the utilization of the internal space. The core of the single-layer power generation module is the graphite substrate 201. Three sides of the graphite substrate 201 are machined into planes to serve as the main heat transfer surfaces 203, while the three vertices of the triangle are preferably machined into rounded transition structures 204 to reduce thermal stress concentration. At each of the three vertices of the equilateral triangle within the graphite substrate 201, a fuel pellet 202 is embedded, forming a triangularly symmetrical heat source distribution; that is, the three fuel pellets 202 are arranged in a triangularly symmetrical manner.

[0055] A stainless steel shell 205 is tightly fitted onto the outer surface of the graphite substrate 201. At the position corresponding to the main heat transfer surface 203, a groove platform 206 with a depth of 1 mm is precisely machined inward on the stainless steel shell 205. That is, the stainless steel plane connected to the thermoelectric power generation device 207 is recessed inward by 1 mm for fixing the thermoelectric power generation device 207.

[0056] Three independent thermoelectric generators 207 are tightly attached to the three groove platforms 206 with thermally conductive silicone grease to achieve efficient heat transfer and thermoelectric conversion.

[0057] Preferably, each thermoelectric device 207 comprises 49 pairs of Bi2Te3-PbTe thermocouples.

[0058] Preferably, the graphite matrix 201 is a high-purity graphite heat source matrix.

[0059] Preferably, the fuel pellet 202 is made of plutonium dioxide fuel pellet.

[0060] Optionally, the stainless steel shell 205 has a wall thickness of 3 mm.

[0061] like Figures 1 to 3 As shown, the power generation function of this isotope power source is achieved through a multi-layer stacking method, where six identical single-layer power generation modules are coaxially stacked vertically to form a compact power generation stack. To achieve precise positioning and stacking stability, each single-layer power generation module has a boss 301 at the center of its lower surface and a corresponding recess 302 on its upper surface. The dimensions of the recess 302 and the boss 301 are matched. During stacking, the boss 301 of the upper single-layer power generation module embeds into the recess 302 of the lower single-layer power generation module, forming a self-aligning structure.

[0062] Preferably, a flexible graphite thermally conductive pad 303 is provided between adjacent single-layer power generation modules to ensure the continuity of axial heat conduction and compensate for thermal expansion.

[0063] Optionally, the height of the boss 301 is 2~3mm.

[0064] Optionally, the depth of the pit 302 is 2~3mm.

[0065] The electrical connections between single-layer power generation modules utilize flexible jumper wires to prevent connection failures caused by thermal stress. The selection of the number of stacking layers has been optimized through thermal-hydraulic processes, ensuring sufficient natural convection drive height while achieving optimal space utilization.

[0066] The thermoelectric generator 207 is connected to a cold-end heat dissipation system, which includes a stainless steel pressure plate 401, a nano-aerogel insulation layer 402, heat dissipation fins 403, a pre-tension spring assembly 404, and a main pressure-bearing cylinder 101. The stainless steel pressure plate 401 is connected to the cold end of the thermoelectric converter; the nano-aerogel insulation layer 402 is filled between the non-heat-transfer surface of the stainless steel shell 205 and the stainless steel pressure plate 401; the main pressure-bearing cylinder 101 is fitted over the stainless steel pressure plate 401, and its outer surface is welded with heat dissipation fins 403 with a height of 4cm to enhance heat exchange; the pre-tension spring assembly 404 is installed between the stainless steel shell 205 and the stainless steel pressure plate 401 and close to the thermoelectric generator to ensure that the thermoelectric generator 207 maintains stable contact under various operating conditions.

[0067] like Figure 1 As shown, the isotope power source is equipped with a complete auxiliary system, including a bottom heat insulation system 501 and an equipment compartment 502.

[0068] A bottom insulation system 501 is installed at the bottom of the power generation stack. The bottom insulation system 501 consists of multiple layers of insulation material and a supporting frame, effectively reducing downward heat loss. An equipment compartment 502 is installed at the top of the power generation stack, which houses a power management unit 503, a monitoring subsystem 504, and an output transmission interface 505. The output transmission interface 505 is designed to be through-type, connecting to an external demand-side interface to realize the collection, conversion, and distribution of electrical energy, as well as real-time monitoring of the system status.

[0069] The bottom insulation system 501 is installed above the lower end cap 102 and consists of high-performance insulation material and support structure, which effectively reduces heat loss downward.

[0070] The monitoring subsystem 504 is used to monitor parameters such as temperature, voltage, and pressure. The power management unit 503 includes a DC-DC converter and protection circuitry.

[0071] The thermal management system employs a completely passive design, requiring no moving parts or external power input. Heat is generated from the fuel pellets 202 (e.g., in a triangular arrangement) and evenly diffused through the highly thermally conductive graphite matrix 201 to the three main heat transfer surfaces 203. The chamfered portions (rounded transition structure 204) are insulated, preventing heat transfer to the outer shell. Heat is then transferred via the stainless steel shell 205 to the thermoelectric generator 207, where some is converted into electricity, and most is transferred as waste heat to the seawater. The waste heat is subsequently discharged through the stainless steel pressure plate 401, the main pressure-bearing cylinder 101, and its heat dissipation fins 403.

[0072] The thermoelectric device 207 generates electricity under the influence of temperature difference, while simultaneously transferring waste heat to the stainless steel pressure plate 401 and the inner wall of the main pressure-bearing cylinder 101. Finally, heat is dissipated through natural convection between the main pressure-bearing cylinder 101 and its heat dissipation fins 403 and the seawater. The stacking of multiple single-layer power generation modules provides the necessary vertical height, stimulating significant natural convection in the still deep-sea environment and forming a stable thermal circulation path. The entire thermal management system, through careful thermal resistance matching design, ensures that the thermoelectric conversion module operates under optimal temperature difference conditions.

[0073] With a total height of approximately 500 mm due to the stacking of six single-layer power generation modules, significant natural convection is generated in the deep sea: cooler seawater flows in from the bottom of the isotopic power source, is heated as it flows upward along the surface of the heat dissipation fins 403, and the heated water flows out from the top, forming a stable natural convection cycle. This passive heat dissipation mechanism does not rely on external power, ensuring that the system can operate effectively under various ocean current conditions.

[0074] Preferably, the heat dissipation fins 403 are arranged in a longitudinal manner and are made of titanium alloy.

[0075] This application employs a multi-layered design for its safety protection system, utilizing a defense-in-depth design to establish multiple protective barriers. The safety protection employs a three-tiered defense-in-depth system: the first level is a double-layered cladding seal for the fuel pellets (inner tantalum alloy, outer stainless steel); the second level is an independent seal for a single-layered power generation module, including the seal between the graphite substrate 201 and the stainless steel shell 205; the third level is an integrated welded pressure-bearing shell system, forming the final safety barrier. All sealing structures have undergone rigorous pressure testing and leak detection.

[0076] The innermost layer (first stage) is the sealed casing of the fuel pellet 202 itself, employing a double-layer structure design. The middle layer (second stage) is an independent seal for each single-layer power generation module, preventing the migration and diffusion of radioactive materials between modules. The outermost layer (third stage) is an integrated welded pressure-bearing shell, forming the final safety barrier. All sealing structures are designed according to the requirements for long service life in deep-sea environments and have undergone rigorous quality control and testing. The three support legs 108 not only provide a stable bottom-sitting function but also, through a reasonable leg layout and bottom design, ensure the power source's anti-overturning and anti-slip capabilities under different seabed topographic conditions.

[0077] As can be seen, this application has successfully overcome the shortcomings of traditional underwater isotope power sources, such as large size, poor heat dissipation, and difficult maintenance, through triangular heat source arrangement, modular stacking design, and integrated pressure-bearing sealing technology, providing a reliable energy solution for long-term deep-sea observation and operation.

[0078] The above description is only a specific embodiment of this application, but the protection scope of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the protection scope of this application.

Claims

1. An underwater compact triangular-arranged thermoelectric isotope power source, characterized in that, include: The pressure-bearing housing system constitutes the main pressure boundary of the power source; The power generation stack, located inside the pressure-bearing shell system, is composed of several single-layer power generation modules stacked coaxially in the vertical direction; A thermal management system is used to convert the heat energy generated by the decay of radioactive isotopes into electrical energy and to remove waste heat to the external seawater. The single-layer power generation module includes a graphite substrate (201) and a stainless steel shell (205) fitted outside the graphite substrate. The graphite substrate (201) contains a fuel pellet (202). The graphite substrate (201) has a main heat transfer surface (203). The stainless steel shell (205) has an inwardly recessed groove platform (206) at a position corresponding to the main heat transfer surface (203). Thermoelectric power generation device (207) is attached to the groove platform (206).

2. The underwater compact triangular arrangement thermoelectric isotope power source according to claim 1, characterized in that, The pressure-bearing shell system adopts an integrated welded structure, including a main pressure-bearing cylinder (101), a lower end cap (102), and an upper end cap (103). The lower end cap (102) is a fixed hemispherical structure, which is welded to the bottom of the main pressure-bearing cylinder (101) through a circumferential weld (104); The upper end cap (103) is a detachable structure. Its flange face (105) is in contact with the flange face at the top of the main pressure-bearing cylinder (101). A metal sealing ring (106) is provided between the mating surfaces. After installation and commissioning, the upper end cap (103) and the main pressure-bearing cylinder (101) are welded and sealed by the final circumferential weld (107).

3. The underwater compact triangular arrangement thermoelectric isotope power source according to claim 2, characterized in that, Three support legs (108) are welded below the lower end cap (102) at 120° angles to form a tripod support structure. Each support leg (108) has a ball joint at its bottom.

4. The underwater compact triangular arrangement thermoelectric isotope power source according to claim 1, characterized in that, The single-layer power generation module adopts a multi-layer stacked integrated structure, and two adjacent single-layer power generation modules are connected by a positioning structure. The lower surface of the upper single-layer power generation module is provided with a boss (301) at the center, and the upper surface of the lower single-layer power generation module is provided with a corresponding recess (302). The boss (301) is embedded in the recess (302) to form a self-centering structure.

5. The underwater compact triangular arrangement thermoelectric isotope power source according to claim 4, characterized in that, The height of the boss (301) is 2~3mm, the depth of the recess (302) is 2~3mm, the electrical connection between the single-layer power generation modules adopts flexible jumper wires, and a flexible graphite thermal pad (303) is also provided between the adjacent single-layer power generation modules.

6. The underwater compact triangular arrangement thermoelectric isotope power source according to claim 1, characterized in that, The thermal management system includes a cold end heat dissipation component, which includes a stainless steel pressure plate (401), a nano aerogel insulation layer (402), heat dissipation fins (403), and a pre-tensioned spring assembly (404). The stainless steel pressure plate (401) is connected to the cold end of the thermoelectric generator (207); The heat dissipation fins (403) are welded to the outer surface of the main pressure-bearing cylinder (101); The preload spring assembly (404) is installed between the stainless steel shell (205) and the stainless steel pressure plate (401) to provide continuous clamping force.

7. The underwater compact triangular arrangement thermoelectric isotope power source according to claim 6, characterized in that, The heat dissipation fins (403) are longitudinally arranged titanium alloy fins, and the nano-aerogel insulation layer (402) is filled between the non-heat transfer surface of the stainless steel shell (205) and the stainless steel pressure plate (401).

8. The underwater compact triangular arrangement thermoelectric isotope power source according to claim 1, characterized in that, The graphite matrix (201) has an equilateral triangle cross section, with a fuel pellet (202) embedded at each of its three vertices, forming a triangularly symmetrical heat source distribution. The three sides of the graphite matrix (201) serve as the main heat transfer surfaces (203).

9. The underwater compact triangular arrangement thermoelectric isotope power source according to claim 1, characterized in that, The power supply also includes an auxiliary system, which includes a bottom insulation system (501) and an equipment compartment (502). The bottom insulation system (501) is disposed between the bottom of the power generation stack and the lower end cap (102); The equipment compartment (502) is located on top of the power generation stack and contains a power management unit (503), a monitoring subsystem (504), and an output transmission interface (505).

10. The underwater compact triangular arrangement thermoelectric isotope power source according to any one of claims 1 to 9, characterized in that, The fuel pellet (202) is made of plutonium dioxide; the graphite matrix (201) is made of high-purity graphite; the thermoelectric generator (207) includes a Bi2Te3-PbTe thermoelectric couple; the main pressure-bearing cylinder (101) and the support leg (108) are both made of titanium alloy.

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