Flat heat pipe coupling plate type fuel double-thermoelectric conversion mode heat pipe cooling reactor

Abstract

The invention belongs to the technical field of energy, and discloses a flat heat pipe coupling plate type fuel double-thermoelectric conversion mode heat pipe cooling reactor, which comprises a heat pipe reactor core section arrangement and a heat pipe reactor coupling thermoelectric conversion device, the section arrangement of the reactor core of the heat pipe reactor specifically comprises a containment structure of the heat pipe reactor, a plate type heat pipe and plate type fuel; the heat pipe pile coupling thermoelectric conversion device comprises a thermionic power generation device, a thermoelectric power generation device and a DC-DC converter. The flat heat pipes and the plate-type fuel are welded on the whole surface, so that clearance heat resistance caused by a heat pipe pile structure framework can be effectively reduced, and the heat transfer efficiency is improved. And on the other hand, the heat transfer efficiency of the plate type heat pipe is better than that of a traditional round pipe type heat pipe under the same power condition, and the plate type fuel has the advantages of being compact in structure and better in heat transfer characteristic.

Description

Technical Field

[0001] The present invention belongs to, but is not limited to, the field of energy technology, and particularly relates to a flat heat pipe coupled plate-type fuel dual thermoelectric conversion mode heat pipe cooled reactor. Background Art

[0002] With the accelerated advancement of the development and deployment of China in the fields of deep space, deep sea, polar regions, etc., the energy issue has increasingly become an important factor restricting mission execution and interest maintenance. Compared with traditional energy systems, nuclear energy shows infinite potential due to its unique advantages. As one of the candidate reactor types of the fourth-generation advanced nuclear energy system, the core feature of the heat pipe cooled reactor is to utilize the heat pipe technology to achieve efficient heat transfer and passive safety of the reactor. With its advantages such as passive heat transfer characteristics, high safety, modular design, and environmental adaptability, it has become an important research direction in the fields of deep space exploration, deep sea navigation, and land-based distributed energy.

[0003] Currently, there are three major technical bottlenecks in the heat pipe cooled reactor: (1) The excessive thermal resistance caused by the gap contact between the traditional cylindrical heat pipe and the fuel rod leads to a significant attenuation of the heat transfer efficiency (experimental data shows that the contact thermal resistance accounts for more than 30%); (2) The low energy utilization rate of the single thermoelectric conversion mode, and the measured thermoelectric conversion efficiency is less than 8%; (3) The high redundancy of the core structure and the limited power density (the existing designs are generally lower than 50 kW / L).

[0004] This technology specifically proposes: ① The integrated configuration of the flattened heat pipe and the plate-shaped fuel, ② The gradient dual-mode thermoelectric conversion system, ③ The modular core integration scheme, to break through the existing technical bottlenecks. It is particularly suitable for compact power supply systems in extreme environments such as deep space detectors and polar workstations. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention provides a flat heat pipe coupled plate-type fuel dual thermoelectric conversion mode heat pipe cooled reactor.

[0006] The present invention is implemented as follows. A flat heat pipe coupled plate-type fuel dual thermoelectric conversion mode heat pipe cooled reactor, the device comprising: the core cross-section layout of the heat pipe reactor and the heat pipe reactor coupled thermoelectric conversion device;

[0007] The core cross-section layout of the heat pipe reactor specifically includes: the containment structure of the heat pipe reactor, the plate heat pipe, and the plate fuel;

[0008] The containment structure of the heat pipe reactor is composed of neutron absorption and shielding materials and structural protection materials, which play a role in protecting the core and radiation protection;

[0009] The plate heat pipe and the plate fuel are coupled and arranged together in an embedded layout; heat transfer is directly carried out through the pipe wall, without the need for the skeleton structure of the traditional "honeycomb coal" type heat pipe stack, effectively reducing the gap thermal resistance brought by the skeleton structure and improving the heat transfer efficiency of the reactor core;

[0010] The heat pipe reactor coupled thermoelectric conversion device includes: a thermionic power generation device, a thermoelectric power generation arrangement, and a DC-DC converter.

[0011] Furthermore, in the heat pipe reactor coupled thermoelectric conversion device, the heat pipe absorbs the heat generated by the fuel element in the evaporation section and transfers it to the thermoelectric conversion device; using the heat pipe as a heat transfer element, its heat transfer efficiency is increased by hundreds or thousands of times compared with conventional metal heat conduction; in addition, as a passive heat transfer element, the heat pipe has higher inherent safety; power generation is carried out through a two-stage thermoelectric conversion device in the condensation section.

[0012] Furthermore, the thermionic power generation device can effectively utilize the region with a relatively high temperature at the initial stage of the condensation section of the high-temperature heat pipe for thermoelectric conversion, and the efficiency can reach 12-15%; power generation is carried out in the thermoelectric power generation mode at the end of the condensation section, and low-grade energy is utilized for thermoelectric conversion, and the efficiency can reach 6-8%; the high-voltage and low-current output by the thermionic power generation and the low-voltage and high-current output by the thermoelectric power generation are matched with the load requirements through parallel connection by the DC-DC converter.

[0013] Combined with the above technical solutions and the solved technical problems, the advantages and positive effects of the technical solution to be protected by the present invention are as follows:

[0014] Traditional heat pipe cooled reactors generally use circular tube heat pipes and rod-shaped fuels, and their combination requires a skeleton structure for cooperation. The existence of the skeleton structure leads to high contact thermal resistance between the heat pipe and the fuel rod, and the heat transfer efficiency is limited. Experimental data shows that this contact thermal resistance accounts for more than 30% of the total thermal resistance, seriously affecting the overall performance of the system. The present invention innovatively uses full-surface welding of flat heat pipes and plate fuels to eliminate the gap thermal resistance, making heat transfer more efficient and uniform. On the other hand, the heat transfer capacity of the plate heat pipe is better than that of the traditional circular tube heat pipe under the same power conditions, and the structure is more compact, making the overall design of the reactor core more optimized, further improving the power density and the system thermal management ability.

[0015] Traditional heat pipe cooled reactors have a single thermoelectric conversion mode, usually relying only on thermoelectric generation (TEG), resulting in low energy utilization efficiency in the high-temperature section. The present invention innovatively proposes a dual-mode collaborative thermoelectric conversion technology. In the high-temperature region (>600 °C) of the heat pipe condensation section, thermionic conversion (TIC) is adopted, and in the low-temperature region (<600 °C), thermoelectric generation (TEG) is used to form a gradient energy utilization system. Through this technical solution, not only the high-quality energy in the high-temperature section is fully utilized, but also the waste heat utilization efficiency in the low-temperature region is effectively improved, increasing the overall thermoelectric conversion efficiency from 8% in the traditional single mode to more than 18%.

[0016] By coupling the high energy density of the plate fuel and the high heat transfer characteristics of the plate heat pipe, the present invention greatly optimizes the core structure, significantly enhancing the power output capacity per unit volume. In addition, the integration of the dual-mode thermoelectric conversion system increases the power density of the heat pipe reactor of the present invention from 50 kW / L in the existing design to 80 kW / L, breaking through the limitations of the volume and weight of the power supply system in extreme environments and providing a more efficient nuclear power supply solution for future application scenarios such as aerospace, deep sea, and remote areas.

[0017] In the current international research on heat pipe cooled reactors, there has been no integrated design of full-surface welding of flat heat pipes and plate fuels, and no public scheme for a gradient dual-mode thermoelectric conversion system has been seen. By integrating high-temperature thermionic conversion and low-temperature thermoelectric generation technologies, the present invention realizes for the first time the cascade energy utilization in the full temperature range of the heat pipe condensation section, breaking through the efficiency limitation of the single thermoelectric conversion mode. At the same time, the innovative design of coupling plate heat pipes and fuels in the field of nuclear reactor heat transfer significantly improves the power density and structural compactness, opening up a new direction for heat pipe cooled reactors.

[0018] In traditional heat pipe cooled reactors, the heat transfer efficiency loss caused by the gap contact between cylindrical heat pipes and fuel rods has always been a key technical problem faced by the industry. By directly welding flat heat pipes and plate fuels, the present invention reduces the gap thermal resistance from more than 30% to less than 5%, greatly improving the heat transfer efficiency. In addition, through the dual-mode thermoelectric conversion technology, the comprehensive energy utilization efficiency of the system is increased from 8% in the traditional single mode to more than 18%, and the modular core integration scheme increases the power density by 60%, providing a more efficient and compact solution for nuclear power supply in extreme environments.

[0019] The industry generally believes that it is difficult for high-temperature thermionic power generation (TIC) and low-temperature thermoelectric power generation (TEG) to work together, and the complexity of the dual-mode system is relatively high, making it difficult to achieve engineering applications. Through the gradient layout of thermoelectric materials (such as using LaB6 cathode in the high-temperature area and Yb-doped skutterudite module in the low-temperature area) and intelligent power management strategies (MPPT maximum power point tracking circuit + redundant control) in this invention, the efficient parallel operation of the two power generation modes is ensured. Under variable working conditions, the efficiency loss of the system is controlled within 5%, greatly improving the engineering practicability of the multi-mode thermoelectric conversion technology, successfully breaking the industry's inherent perception of the feasibility of the dual-mode thermoelectric conversion technology, and laying an important technical foundation for future high-efficiency and compact nuclear power supply systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is the cross-sectional layout diagram of the core of the heat pipe reactor provided by the embodiment of the present invention;

[0021] Figure 2 is the structural diagram of the heat pipe reactor coupled with a thermoelectric conversion device provided by the embodiment of the present invention;

[0022] In the figure: 1. Containment structure of the heat pipe reactor; 2. Plate heat pipe; 3. Plate fuel; 4. Thermionic power generation device; 5. Thermoelectric power generation layout; 6. DC-DC converter. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0024] As Figure 1 、 2 shown, the embodiment of the present invention provides a flat heat pipe coupled with a plate fuel dual-thermoelectric conversion mode heat pipe-cooled reactor, and the device includes: the cross-sectional layout of the core of the heat pipe reactor and the heat pipe reactor coupled with a thermoelectric conversion device;

[0025] The cross-sectional layout of the core of the heat pipe reactor specifically includes: the containment structure 1 of the heat pipe reactor, the plate heat pipe 2, and the plate fuel 3;

[0026] The containment structure of the heat pipe reactor is composed of neutron absorption and shielding materials and structural protection materials, which play the role of protecting the core and radiation protection;

[0027] The plate heat pipe and the plate fuel are coupled and arranged together, and are embedded and arranged; heat transfer is directly carried out through the pipe wall, effectively reducing the gap thermal resistance and improving the heat transfer efficiency of the core;

[0028] The heat pipe reactor-coupled thermoelectric conversion device includes: a thermionic power generation device 4, a thermoelectric power generation arrangement 5, and a DC-DC converter 6.

[0029] In the heat pipe reactor-coupled thermoelectric conversion device, the heat pipe absorbs the heat generated by the fuel element in the evaporation section and transfers it to the thermoelectric conversion device; using the heat pipe as a heat transfer element, its heat transfer efficiency is hundreds or thousands of times higher than that of conventional metal heat conduction; in addition, as a non-energy heat transfer element, the heat pipe has higher inherent safety; power generation is carried out through a two-stage thermoelectric conversion device in the condensation section.

[0030] The thermionic power generation device 4 can effectively utilize the region with a relatively high temperature at the initial stage of the condensation section of the high-temperature heat pipe for thermoelectric conversion, and the efficiency can reach 12-15%; a thermoelectric power generation mode is adopted at the end of the condensation section for power generation, and low-grade energy is used for thermoelectric conversion, and the efficiency can reach 6-8%; the high-voltage and low-current output by the thermionic power generation and the low-voltage and high-current output by the thermoelectric power generation are paralleled through the DC-DC converter 6 to match the load demand.

[0031] 1. Gradient thermoelectric material layout

[0032] High-temperature region: For thermionic emission, a lanthanum-doped lanthanum hexaboride (LaB6) cathode is used, with a temperature resistance > 1000 °C and a work function as low as 2.7 eV.

[0033] Low-temperature region: The ZT value of the skutterudite thermoelectric module is increased to 1.4 (at 500 °C) by filling Yb nanoparticles.

[0034] 2. Internal enhanced heat transfer in plate-shaped heat pipes

[0035] Along the evaporation section to the condensation section of the heat pipe, there are many groove structures, which can effectively provide capillary force to pump and reflux the working fluid, improving the passive heat transfer characteristics of the heat pipe. In addition, laser etching of microchannels on the inner surface of the heat pipe can effectively improve the capillary force. A liquid-absorbing core is spot-welded on the inner wall of the heat pipe to further improve the reflux ability of the working fluid in the heat pipe.

[0036] 3. Power management strategy

[0037] The thermionic module and the thermoelectric module are independently controlled through a maximum power point tracking (MPPT) circuit to optimize the load impedance in real time.

[0038] An interleaved parallel Boost topology is adopted to stabilize the output voltage fluctuation within the range of ±1%.

[0039] When the variable power causes the temperature change of the condensation section of the heat pipe, the efficiency adjustment of the thermoelectric conversion module may even fail because the temperature is out of the power generation range. The adjacent module redundant circuit takes over the load, and the system efficiency loss is within 5%.

[0040] The present invention is applicable to compact nuclear power sources for extraterrestrial bases such as the Moon and Mars, and can provide continuous and stable energy for detectors, communication equipment, and life support systems. Due to the extremely large temperature difference in the outer space environment, traditional power systems are difficult to operate stably for a long time. However, the present invention adopts dual-mode thermoelectric conversion + high-efficiency heat pipe cooling, which can maintain efficient energy conversion in extreme temperature environments and provide a more reliable energy solution for future deep space exploration.

[0041] The present invention can be used as a high-power density power source for unmanned underwater vehicles (UUVs) or deep-sea workstations, providing stable energy for long-term underwater operations. Compared with traditional nuclear power systems, the plate fuel + heat pipe direct coupling structure of the present invention can maintain good heat transfer performance in the underwater high-pressure environment. The dual-mode thermoelectric conversion technology can maximize the utilization of energy in different temperature ranges, improve the endurance of the underwater vehicle, and enable it to perform detection tasks underwater for a longer time.

[0042] The present invention can be used as a distributed energy system for polar research stations, border defense posts, and remote observation stations, and is particularly suitable for extreme low-temperature environments. Under extremely cold conditions, the efficiency of traditional battery storage and diesel generators drops significantly. However, the high-efficiency heat pipe heat transfer + dual-mode thermoelectric conversion system of the present invention can operate stably and adapt to extreme climate conditions to ensure long-term energy supply.

[0043] The present invention can be used as a backup power source or off-grid energy to meet the needs of disaster emergency power supply, military covert power supply, etc. Compared with traditional nuclear micro-reactors, the modular core design of the present invention makes it easier to expand and can provide stable and efficient power output in small-scale nuclear power applications, improving safety and practicality.

[0044] Evidence related to the technical effects obtained in the embodiments of the present invention.

[0045] 1. Improvement in heat transfer efficiency and reduction in contact thermal resistance

[0046] According to Fourier's law of heat conduction, the contact thermal resistance R contact is inversely proportional to the contact area A, that is:

[0047] R contact = 1 / h c A

[0048] where h c is the contact heat transfer coefficient. The line contact between the traditional cylindrical heat pipe and the fuel rod results in a small contact area (A 线接触 ∝ r·L, r is the radius, L is the length), while the planar contact area between the plate heat pipe and the fuel in the present invention is significantly increased (A 面接触 ∝ W·L, W is the plate width). Combining with the vacuum diffusion welding technology (interface defect rate ≤ 0.1%), the contact heat transfer coefficient h c is improved.

[0049] 2. Energy Efficiency Optimization Theory of Dual-Mode Thermoelectric Conversion

[0050] a. Thermionic Power Generation Efficiency in High-Temperature Region

[0051] The current density J of thermionic power generation follows the Richardson-Dushman equation:

[0052] J = AT 2 e -φ / kT

[0053] where A is the emission constant, φ is the work function, and T is the cathode temperature. Using a LaB6 cathode (φ = 2.7 eV) at 650 °C, the theoretical current density J = 12 A / cm 2 , combined with optimized electrode spacing (d = 50 μm), the theoretical conversion efficiency can reach 15.5%.

[0054] b. Thermoelectric Power Generation Performance in Low-Temperature Region

[0055] The dimensionless figure of merit ZT of skutterudite thermoelectric materials determines the upper limit of the conversion efficiency:

[0056]

[0057] By doping with Yb nanoparticles (ZT = 1.4 at around 500 °C), at ΔT = 300 °C (Th = 500 °C, Tc = 200 °C), the theoretical efficiency reaches 8.2%.

[0058] c. Energy Level Matching of Dual-Mode Synergy

[0059] The high voltage output (V TI ≈ 0.8 V) of thermionic power generation and the low voltage (V TEG ≈ 0.2 V) of thermoelectric power generation are connected in parallel through a DC-DC converter. The total efficiency η total of the system can be modeled as:

[0060]

[0061] When P TI :P TEG = 3:2, the theoretical overall efficiency η total＝ is 18.3%. The present invention can achieve a smaller heat transfer thermal resistance and a higher overall conversion efficiency.

[0062] It should be noted that the embodiments of the present invention can be implemented by hardware, software, or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or dedicated designed hardware. Those of ordinary skill in the art can understand that the above devices and methods can be implemented using computer-executable instructions and / or included in processor control code, such as provided on a carrier medium such as a disk, CD, or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The devices and their modules of the present invention can be implemented by hardware circuits of programmable hardware devices such as very large scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or field programmable gate arrays, programmable logic devices, etc., can also be implemented by software executed by various types of processors, or can be implemented by a combination of the above hardware circuits and software such as firmware.

[0063] As described above, only the specific embodiments of the present invention are provided, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention.

Claims

1. A flat heat pipe coupled plate-type fuel dual thermoelectric conversion mode heat pipe cooled reactor, characterized in that Comprising: The core cross-sectional arrangement of the heat pipe reactor, including a containment structure, plate heat pipes, and plate fuels; The heat pipe reactor coupled thermoelectric conversion device, including a thermionic power generation device, a thermoelectric generation arrangement, and a DC-DC converter; The plate heat pipes and the plate fuels adopt a full-surface welding structure. The evaporation section of the plate heat pipe is in direct contact with the fuel and transfers heat through the pipe wall; The thermionic power generation device is arranged in the high-temperature area of the heat pipe condensation section, and the thermoelectric generation arrangement is arranged in the low-temperature area of the heat pipe condensation section; The DC-DC converter is used to adjust the voltage of the electrical outputs of the thermionic power generation device and the thermoelectric generation arrangement and match the load requirements.

2. The heat pipe cooled reactor with flat heat pipe coupled plate type fuel and dual thermoelectric conversion modes according to claim 1, characterized in that The containment structure of the heat pipe reactor is composed of neutron-absorbing materials, shielding materials, and structural protection materials, and forms a closed structure around the heat pipe reactor.

3. The heat pipe cooled reactor with flat heat pipe coupled plate type fuel for dual thermoelectric conversion modes according to claim 1, characterized in that, The evaporation section surface of the plate heat pipe is provided with a microchannel structure, and a wick is spot-welded to the inner wall of the heat pipe to enhance the capillary reflux ability of the working fluid.

4. The heat pipe cooled reactor with a flat heat pipe coupled plate type fuel dual thermoelectric conversion mode according to claim 1, characterized in that, The thermionic power generation device uses a lanthanum-doped lanthanum hexaboride (LaB6) cathode, and the cathode spacing is less than 100 μm.

5. The heat pipe cooled reactor with a flat heat pipe coupled plate type fuel dual thermoelectric conversion mode according to claim 1, characterized in that, The thermoelectric generation arrangement uses skutterudite thermoelectric materials and is filled with Yb nanoparticles to improve the thermoelectric conversion efficiency.

6. The heat pipe cooled reactor with flat heat pipe coupled plate type fuel dual thermoelectric conversion mode according to claim 1, characterized in that, The DC-DC converter adopts an interleaved parallel Boost topology and has a maximum power point tracking (MPPT) circuit to optimize the load impedance.

7. The heat pipe cooled reactor with a flat heat pipe coupled plate type fuel dual thermoelectric conversion mode according to claim 1, characterized in that, The heat pipe reactor adopts a modular design, and the heat pipe core units can be expanded in parallel to meet different power requirements.

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