Thermonic power generation device based on micro-nano structure emitter and cesium emptying device

Abstract

The invention discloses a thermionic power generation device based on a micro-nano structure emitter and a cesium emptying device, and belongs to the technical field of thermoelectric conversion. Comprising a shell, an emitting electrode, a receiving electrode, a heat source assembly, a cesium conveying assembly, a vacuumizing assembly and an emptying assembly, wherein the emitting electrode and the receiving electrode are oppositely arranged in the shell; the heat source assembly is installed on the shell and transmits heat to the emitting electrode; the opposite faces of the emitting electrode and the receiving electrode are arranged to be micro-nano structure surfaces, and the cesium conveying assembly conveys cesium steam to the position between the emitting electrode and the receiving electrode. The method can realize heating, discharging and treatment of cesium between polar plates on the premise of not destroying the vacuum structure of the thermionic power generation device, improves the efficiency and service life of the thermionic power generation device, improves the utilization rate of cesium, avoids pollution of cesium to the environment, can reduce the surface work function of the emitter through the micro-nano structure, and improves the efficiency of the thermionic power generation device. The emission condition of hot electrons is improved, the space charge barrier effect is inhibited, and the conversion efficiency from heat energy to electric energy is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermoelectric conversion, and particularly relates to a thermionic power generation device based on a micro-nano structure emitter and a cesium evacuation device. Background Art

[0002] The general structural schematic diagram of a thermionic power generation device is as Figure 1 shown, and it mainly consists of an emitter for emitting thermoelectrons, a receiver for capturing thermoelectrons, a ceramic package, a vacuum assistance system, etc. When the heat released by the heat source is transferred to the emitter through the heat transfer device, some electrons on the surface of the emitter gain sufficient energy by absorbing heat energy, escape from the surface of the emitter after overcoming the surface work function, and are emitted to the outside. Driven by the initial kinetic energy, some electrons with high enough self-energy cross the electrode gap and are collected by the receiver. Under the action of the potential difference between the two plates, the electrons reaching the receiver do work through an external load, realizing the conversion of heat energy into electrical energy.

[0003] Theoretically, the thermoelectric conversion efficiency of a thermionic power generation device can reach 40%, however, the actual thermoelectric conversion efficiency is only between 6% and 13%, significantly lower than the theoretical value. One of the main reasons for this gap is the space charge barrier effect generated during the operation of the thermionic power generation device. The space charge barrier effect refers to the spatial potential distribution formed in the electrode gap during the generation, transport, and collection of thermoelectrons. Generally, the space charge barrier effect will hinder the movement of electrons, resulting in a decrease in the thermoelectric conversion efficiency. Specifically, when the high-temperature emitter emits electrons outward, the energy of the emitted thermoelectrons follows the Maxwell-Boltzmann distribution law. Among them, the thermoelectrons in the low-energy distribution interval cannot pass through the electrode gap due to the existence of the potential barrier between the electrodes, so a negatively charged spatial electron cloud will be formed in the electrode gap. The spatial electron cloud will interact with the subsequent emitted electrons to form a spatial repulsive force field, causing the subsequent emitted thermoelectrons to scatter in other directions, hindering the normal transport and collection of thermoelectrons, and ultimately resulting in the thermoelectric conversion efficiency of the thermionic power generation device being much lower than the theoretical value.

[0004] In order to increase the conversion efficiency of heat energy to electrical energy, a conventional method is to fill cesium between the two plates. The boiling point of cesium is relatively low. After filling cesium, cesium will exist in the form of cesium vapor between the emitter and the receiver. The electrons emitted by the emitter will collide with cesium atoms. When the cesium atoms obtain enough energy, they will be excited and ionized into cesium ions. The positively charged cesium ions will neutralize the spatial electron cloud, thereby suppressing the space charge barrier, increasing the electron passing rate, and thus significantly improving the thermoelectric conversion efficiency.

[0005] Although cesium has a significant effect on improving the performance of thermionic power generation devices, there are also two problems: corrosion of plate materials and environmental pollution. First, thermionic power generation devices operate in a high-temperature environment above 1400K. Under this condition, long-term contact between gas-phase cesium and plate materials will form metal crystals; at the same time, the presence of a small amount of cesium oxide will also undergo a reduction reaction with the plate material. These two effects work together to cause corrosion of the plates, reducing the life and performance of thermionic power generation devices. Second, cesium metal is toxic. If it is directly discharged, it will pollute the environment, reduce its environmental friendliness and cause harm to human health.

[0006] The work function of the emitter material is another key physical factor that affects the thermoelectric conversion efficiency of thermionic power generation devices. The work function refers to the difference in potential energy between the vacuum energy level and the Fermi level of the material. When the electron energy is greater than the vacuum energy level, the electron can escape from the material. One way to reduce the work function of the emitter material is to set up a micro-nano structure on its surface. When the thermionic power generation device is in operation, an electric field will be generated between the emitter and the receiver. Due to the tip discharge effect at the micro-nano structure, the electric field strength will increase, and the electrons in the material will break through the constraints of the electrode material and emit through the field emission effect. Compared with ordinary emitters, emitters with micro-nano structures emit more electrons at the same voltage difference and have a lower work function. Summary of the invention

[0007] The present invention provides a thermionic power generation device based on a micro-nanostructure emitter and a cesium exhaust device in order to more efficiently utilize cesium vapor, inhibit the adverse effects of its corrosion on thermionic power generation devices, and prolong the service life of thermionic power generation devices while improving their environmental friendliness.

[0008] The technical solution adopted by the present invention is:

[0009] A thermionic power generation device based on a micro-nano structure emitter and a cesium exhaust device comprises a shell, an emitter and a receiving electrode arranged opposite to each other in the shell, a heat source component mounted on the shell and transferring heat to the emitter, a cesium transport component, a vacuum component and an exhaust component connected to the inner cavity of the shell; the opposing surfaces of the emitter and the receiving electrode are arranged as micro-nano structure surfaces, and the cesium transport component transports cesium vapor between the emitter and the receiving electrode.

[0010] Compared with the prior art, the present invention has the following beneficial effects:

[0011] 1. The present invention can realize the heating, discharge and treatment of cesium between the plates without destroying the vacuum structure of the thermionic power generation device, thereby extending the efficiency and life of the thermionic power generation device, improving the utilization rate of cesium and avoiding cesium pollution to the environment. At the same time, through the micro-nano structure, the emitter surface work function can be reduced, the emission conditions of hot electrons can be improved, the charge effect can be suppressed, and the conversion efficiency of thermal energy to electrical energy can be increased.

[0012] 2. The present invention has low cost, simple operation, and is easy to be applied to other thermionic power generation devices, which can provide solid technical support for the long-term stable operation of thermionic power generation devices.

[0013] 3. The present invention performs micro-nano structuring treatment on the electrode surface, enhances the thermionic emission performance of the emitter and optimizes the electron transmission path, which helps to improve the power generation efficiency and stability.

[0014] 4. The cavity wall of the present invention can be heated, which effectively reduces the attachment of cesium to the cavity wall, improves the utilization rate of cesium, and enhances the efficiency of cesium vapor evacuation.

[0015] 5. Starting from the problem that cesium corrodes metal materials at high temperatures, which affects the service life of thermionic power generation devices, the present invention realizes the collection and treatment of cesium by improving the cesium evacuation system, inhibits the corrosion of cesium on the metal cavity wall, and extends the service life of thermionic power generation devices.

[0016] 6. The present invention effectively couples the cesium heating and evacuation systems. The evacuation system performs recovery treatment on the excessive cesium vapor, and the heating system optimizes the utilization rate of cesium, reduces waste and environmental pollution, and realizes the double improvement of economy and environmental protection.

[0017] 7. Starting from the non-pollution property, the present invention can realize the harmless treatment of cesium, avoiding the pollution of the laboratory environment by cesium and the impact on human health.

[0018] 8. During the evacuation process, the present invention uses a feedback control system to link the heating and multiple exhaust pumps to form an efficient evacuation treatment mechanism. Description of the Drawings

[0019] Figure 1 is an existing thermionic power generation device;

[0020] Figure 2 is a schematic structural diagram of the present invention;

[0021] Figure 3 is the front view of the present invention;

[0022] Figure 4 is the top view of the present invention;

[0023] Figure 5 is the schematic structural diagram of the adjusting rod of the present invention;

[0024] Wherein: 1. Cesium delivery component; 101. Heater; 102. C4 valve; 103. Cesium delivery pipe; 2. Housing; 3. Receiver electrode; 4. Spacing adjustment device; 401. Ball seat; 402. Sphere; 403. Adjusting rod; 4031. Rod body; 4032. Cap; 404. Bellows; 405. Telescopic rod; 5. Vacuum pumping component; 501. Vacuum gauge; 502. C1 valve; 503. C2 valve; 504. Mechanical pump; 505. Molecular pump; 506. Ion pump; 507. C3 valve; 6. Drainage component; 601. C5 valve; 602. Drainage pipe; 603. Oil pump; 604. Bellows; 605. Water-filled container; 7. Emitter electrode; 8. Heat source component; 801. Heat collection device; 802. Heat transfer device. Detailed implementation mode

[0025] In order to better understand the purpose, structure and function of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0026] As Figures 2 to 5 shown, the present invention provides a thermionic power generation device based on a micro-nano structure emitter electrode and a cesium drainage device, including a housing 2, an emitter electrode 7 and a receiver electrode 3 oppositely arranged in the housing 2, a heat source component 8 installed on the housing 2 and transferring heat to the emitter electrode 7, a cesium delivery component 1, a vacuum pumping component 5 and a drainage component 6 communicated with the inner cavity of the housing 2; the opposite surfaces of the emitter electrode 7 and the receiver electrode 3 are set as micro-nano structure surfaces, and the cesium delivery component 1 delivers cesium vapor between the emitter electrode 7 and the receiver electrode 3.

[0027] As Figures 2 to 3 shown, the cesium delivery component 1 includes a heater 101, a C4 valve 102 and a cesium delivery pipe 103; one end of the cesium delivery pipe 103 is communicated with the inner cavity of the housing 2, the other end of the cesium delivery pipe 103 is communicated with a cesium source, and a heater 101 and a C4 valve 102 are installed on the cesium delivery pipe 103.

[0028] As Figures 2 to 3 shown, the vacuum pumping component 5 includes a vacuum gauge 501, a C1 valve 502, a C2 valve 503, a C3 valve 507, a mechanical pump 504, a molecular pump 505 and an ion pump 506; the mechanical pump 504 is communicated with the inner cavity of the housing 2 through a first pipeline, a C1 valve 502 is installed on the first pipeline, the molecular pump 505 is communicated with the inner cavity of the housing 2 through a second pipeline, a C2 valve 503 is installed on the second pipeline, the ion pump 506 is communicated with the inner cavity of the housing 2 through a third pipeline, a C3 valve 507 is installed on the third pipeline, and the vacuum gauge 501 is installed on the housing 2 for detecting the pressure condition of the inner cavity of the housing 2.

[0029] As Figures 2 to 3As shown, the evacuation assembly 6 includes an oil pump 603, an evacuation pipe 602, a C5 valve 601, and a bellows 604. The inlet end of the oil pump 603 is communicated with the inner cavity of the housing 2 through the evacuation pipe 602. The outlet end of the oil pump 603 discharges cesium vapor into the water-containing container 605 through the bellows 604. The C5 valve 601 is installed on the evacuation pipe 602.

[0030] As Figures 2 to 3 shown, the heat source assembly 8 includes a heat collection device 801 and a heat transfer device 802. The heat collection device 801 is installed on the outer wall of the housing 2. The heat collection device 801 transfers heat to the emitter 7 inside the housing 2 through the heat transfer device 802.

[0031] The side wall of the housing 2 is a sandwich structure, and a cavity wall heating system is provided inside the side wall of the housing 2.

[0032] The heat collection device 801, the heat transfer device 802, and the cavity wall heating system can all adopt existing devices.

[0033] As Figure 2 shown, the thermionic power generator device based on the micro-nano structure emitter and cesium evacuation device further includes a spacing adjustment device 4. The receiving electrode 3 is installed on the spacing adjustment device 4, and the spacing adjustment device 4 is installed on the housing 2. It is used to adjust the distance between the emitter 7 and the receiving electrode 3 to facilitate the influence of the experimental distance on the result.

[0034] As Figure 2 shown, the spacing adjustment device 4 includes two adjustment components. Each adjustment component includes a ball seat 401, a sphere 402, an adjustment rod 403, a bellows 404, and a telescopic rod 405. The ball seat 401 is installed on the back surface of the emitter 7. The sphere 402 is installed inside the ball seat 401. One end of the sphere 402 is connected to the adjustment rod 403. The other end of the adjustment rod 403 passes through a perforation provided on the side wall of the housing 2 and is connected to the telescopic rod 405. The telescopic rod 405 is fixedly connected to the outer wall of the housing 2 through a bracket, or the telescopic rod 405 is supported on the ground through a bracket. One end of the bellows 404 is hermetically connected to the perforation outside the housing 2. The other end of the bellows 404 is sleeved on the adjustment rod 403 and is hermetically connected to the adjustment rod 403. The bellows 404 plays a sealing role to avoid cesium leakage.

[0035] The two adjustment components can adjust the distance between the emitter 7 and the receiving electrode 3 together, or can individually extend or retract one telescopic rod 405 to adjust the angle of the receiving electrode 3 to facilitate the influence of the experimental angle on the result.

[0036] As Figure 5As shown in the figure, the adjusting rod 403 includes a rod body 4031, a cap 4032 and a heating rod; the rod body 4031 is provided with a cavity, one end is a sealed end and the other end is an open end. The sealed end of the rod body 4031 is connected to the sphere 402, and the open end of the rod body 4031 is threadedly connected to the cap 4032. The middle of the cap 4032 is provided with an opening, and the cap 4032 is connected to the telescopic rod 405. This connection method can be a shaft connection. The heating rod is placed in the cavity of the rod body 4031. The lead wire of the heating rod passes through the opening of the cap 4032. The temperature of the receiving electrode 3 is adjusted by the heating rod to facilitate the influence of the experimental temperature on the results.

[0037] Experimental process:

[0038] 1. Create a vacuum environment: First, open the C1 valve 502, start the mechanical pump 504 to pre-pump the housing 2, and use the resistance gauge and the vacuum gauge 501 to monitor the change of the vacuum degree of the vacuum chamber of the housing 2. When the chamber pressure drops to the 10 Pa level, close the C1 valve 502 and the mechanical pump 504, open the molecular pump 505 and the C2 valve 503, and further reduce the vacuum chamber pressure from the 10 Pa level to the 10-2 Pa magnitude. When the vacuum chamber pressure stabilizes at the 10-2 Pa level, then close the C2 valve 503 and the molecular pump 505, open the C3 valve 507, start the ion pump 506, and reduce the vacuum chamber pressure from 10-2 Pa to the 10-6 Pa level to create working conditions for the thermionic generator device;

[0039] 2. Fill cesium vapor: First, close the C3 valve 507 to prevent cesium vapor from entering the ion pump 506, thereby causing damage to the ion pump 506. Subsequently, turn on the cesium tube heater 101 to heat the cesium delivery tube 103 sufficiently to ensure that cesium can enter the vacuum chamber more fully subsequently. After the cesium is heated sufficiently, open the C4 valve 102 to fill the vacuum chamber with cesium vapor;

[0040] 3. Perform thermoelectric conversion: Use the thermionic generator device to perform thermoelectric conversion. During the thermoelectric conversion process, turn on the chamber wall heating system to heat the device chamber wall to prevent high-temperature cesium vapor from liquefying on the relatively low-temperature chamber wall and reducing the cesium ion concentration in the chamber. At this time, due to the filling of cesium vapor, the chamber pressure will rise to about 0.1 Pa;

[0041] 4. Cesium vapor discharge: After the thermoelectric conversion is completed, close valve C4 (102), start the downstream oil pump (603), open valve C5 (601), and extract the cesium vapor in the chamber. When the air pressure in the chamber drops to about 10-2 Pa, start the mechanical pump (504), open valve C1 (502), and slowly ventilate the chamber to restore the air pressure to the order of 0.1 Pa. Then close valve C1, open valve C5 (601) again, start the downstream oil pump (603), and extract the cesium vapor. Repeat this step multiple times to completely discharge the cesium vapor. It should be noted that the chamber wall heating system should be kept on during the cesium vapor discharge to effectively inhibit the condensation of high-temperature cesium vapor on the vacuum chamber wall;

[0042] 5. Cesium collection and treatment: Set a water container (605) filled with pure water downstream of the oil pump (603), and introduce the gas extracted by the oil pump (603) into the water. The cesium vapor in the gas will react with water to form alkaline cesium hydroxide, thus achieving pollution-free treatment of cesium.

[0043] 6. Residual cesium inspection: After multiple extractions, replace the water in the water container (605), and wait until after sufficient ventilation, then drop phenolphthalein solution. If the liquid in the container does not change color, it proves that the cesium has been completely discharged.

[0044] It can be understood that the present invention is described by means of some embodiments. Those skilled in the art know that without departing from the spirit and scope of the present invention, various changes or equivalent substitutions can be made to these features and embodiments. In addition, under the teaching of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application belong to the scope protected by the present invention.

Claims

1. A thermionic power generation device based on a micro-nanostructure emitter and a cesium evacuation device, characterized in that: The invention comprises a shell (2), an emitter (7) and a receiver (3) arranged relatively inside the shell (2), a heat source component (8) installed on the shell (2) and transferring heat to the emitter (7), a cesium transport component (1) connected to the inner cavity of the shell (2), a vacuum component (5) and an exhaust component (6); the opposing surfaces of the emitter (7) and the receiver (3) are arranged as micro-nano structure surfaces, and the cesium transport component (1) transports cesium vapor between the emitter (7) and the receiver (3).

2. The thermionic power generation device based on a micro-nanostructure emitter and a cesium exhaust device according to claim 1, characterized in that: The cesium transport component (1) comprises a heater (101), a C4 valve (102) and a cesium transport pipe (103); one end of the cesium transport pipe (103) is connected to the inner cavity of the shell (2), and the other end of the cesium transport pipe (103) is connected to the cesium source; the heater (101) and the C4 valve (102) are installed on the cesium transport pipe (103).

3. The thermionic power generation device based on a micro-nanostructure emitter and a cesium exhaust device according to claim 1, characterized in that: The vacuum pumping component (5) comprises a vacuum gauge (501), a C1 valve (502), a C2 valve (503), a C3 valve (507), a mechanical pump (504), a molecular pump (505) and an ion pump (506); the mechanical pump (504) is connected to the inner cavity of the shell (2) via a first pipeline, the first pipeline is provided with a C1 valve (502), the molecular pump (505) is connected to the inner cavity of the shell (2) via a second pipeline, the second pipeline is provided with a C2 valve (503), the ion pump (506) is connected to the inner cavity of the shell (2) via a third pipeline, the third pipeline is provided with a C3 valve (507), and the vacuum gauge (501) is installed on the shell (2).

4. The thermionic power generation device based on a micro-nanostructure emitter and a cesium exhaust device according to claim 1, characterized in that: The drain assembly (6) comprises an oil pump (603), a drain pipe (602), a C5 valve (601) and a bellows (604); the inlet end of the oil pump (603) is connected to the inner cavity of the shell (2) through the drain pipe (602), and the outlet end of the oil pump (603) discharges cesium vapor into a water container (605) through the bellows (604); and the drain pipe (602) is installed with a C5 valve (601).

5. The thermionic power generation device based on a micro-nanostructure emitter and a cesium exhaust device according to claim 1, characterized in that: The heat source assembly (8) comprises a heat collection device (801) and a heat transfer device (802); the heat collection device (801) is mounted on the outer wall of the shell (2), and the heat collection device (801) transfers heat to the emitter (7) on the inner side of the shell (2) through the heat transfer device (802).

6. The thermionic power generation device based on a micro-nanostructure emitter and a cesium exhaust device according to claim 1, characterized in that: The side wall of the shell (2) is a sandwich structure, and a cavity wall heating system is provided inside the side wall of the shell (2).

7. The thermionic power generation device based on a micro-nanostructure emitter and a cesium exhaust device according to claim 1, characterized in that: The thermionic power generation device based on a micro-nanostructure emitter and a cesium exhaust device further comprises a spacing adjustment device (4); the receiving electrode (3) is mounted on the spacing adjustment device (4), and the spacing adjustment device (4) is mounted on a housing (2).

8. The thermionic power generation device based on a micro-nanostructure emitter and a cesium exhaust device according to claim 7, characterized in that: The spacing adjustment device (4) comprises two adjustment components, each of which comprises a ball seat (401), a ball (402), an adjustment rod (403), a bellows (404) and a telescopic rod (405); the ball seat (401) is mounted on the back of the emitter (7), the ball (402) is mounted in the ball seat (401), the ball (402) is connected to one end of the adjustment rod (403), the other end of the adjustment rod (403) passes through a through hole provided on the side wall of the shell (2) and is connected to the telescopic rod (405), the telescopic rod (405) is fixedly connected to the outer wall of the shell (2) through a bracket, or the telescopic rod (405) is supported on the ground through a bracket, one end of the bellows (404) is sealed and connected to the through hole on the outside of the shell (2), and the other end of the bellows (404) is sleeved on the adjustment rod (403) and is sealed and connected to the adjustment rod (403).

9. The thermionic power generation device based on a micro-nanostructure emitter and a cesium exhaust device according to claim 8, characterized in that: The adjusting rod (403) comprises a rod body (4031), a cap (4032) and a heating rod; the rod body (4031) is provided with a cavity, and one end is a sealed end and the other end is an open end, the sealed end of the rod body (4031) is connected to the sphere (402), the open end of the rod body (4031) is threadedly connected to the cap (4032), an opening is provided in the middle of the cap (4032), the cap (4032) is connected to the telescopic rod (405), and the heating rod is placed in the cavity of the rod body (4031).

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