Combustor for power generation by coupling combustion in porous media with thermionic electricity

Abstract

The application discloses a kind of porous medium combustion coupling thermoelectric power generation burner.The air preheating passage in the application is arranged on the outer wall of the thermoelectric power generation structure, and the air and fuel are respectively introduced into the premixing chamber after passing through the preheating passage, and then the premixed air and fuel are ignited and burned in the porous medium burner, forming a stable gas combustion flame in the porous medium, and the combustion heat is transferred out in the form of coupled porous medium surface radiation heat transfer and high-temperature flue gas convection heat transfer.The thermoelectric power generation structure is arranged on the wall surface of the burner, and the external circuit and load are used for the utilization of combustion waste heat.The air preheating passage is arranged in the application to reduce the absolute temperature of the anode, so as to prevent the anode from working at a high temperature, inhibit the effective conversion of thermoelectricity, and improve the thermoelectric power generation efficiency.Meanwhile, the air is preheated, and the combustion efficiency is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of porous media combustion technology and relates to a porous media combustion coupled thermoelectronic power generation burner. Background Technology

[0002] Thermoelectric power generation is a technology that converts heat energy into electrical energy. However, current thermoelectric power generation still faces some challenges. Firstly, traditional thermoelectric power generation uses heat sources such as hydrogen combustion, which suffers from uneven temperature distribution. This significantly impacts the stability of the generated electricity and the lifespan of the thermoelectric power generation structure. Secondly, the anode operating temperature in thermoelectric power generation structures is relatively high (typically between 500-800℃), leading to excessive back-emission of electrons from the anode, thus inhibiting effective thermoelectric conversion.

[0003] Porous media reactors have advantages such as high combustion rate, uniform temperature distribution, and high combustion efficiency during combustion, making them a better choice for the heat source of thermionic power generation. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a porous medium combustion coupled thermoelectric power generation burner.

[0005] The present invention includes an air preheating channel, a premixing chamber, an airflow distributor, a porous media burner, and a thermoelectric power generation structure. An air preheating channel is provided circumferentially in the porous media burner. External air enters the premixing chamber below the porous media burner after passing through the air preheating channel. A gas inlet is opened on one side of the premixing chamber. The gas and preheated air are premixed in the premixing chamber and then enter the porous media burner for combustion through the airflow distributor. A thermoelectric power generation structure is provided on the wall of the porous media burner.

[0006] The main heat generated by combustion is transferred out through heat transfer via coupled porous media surface radiation and high-temperature flue gas convection. Some of the heat is transferred to the porous media burner wall through high-temperature flue gas convection, thermal radiation, and thermal conduction, and then to the cathode of the thermionic power generation structure. The thermionic power generation structure uses the combustion waste heat to convert thermal energy into electrical energy.

[0007] The beneficial effects of this invention are as follows:

[0008] By incorporating an air preheating channel, the anode temperature is lowered to prevent excessively high anode operating temperatures from inhibiting effective thermoelectric conversion and thus improving the efficiency of thermionic power generation. Simultaneously, it preheats the air, significantly enhancing combustion efficiency.

[0009] The design of a serrated or corrugated annular wall can increase the contact area with the cathode, thereby increasing the total amount of thermionic emission and the magnitude of the current.

[0010] Porous media, as a heat source for thermionic power generation, possess characteristics such as high combustion intensity, strong combustion stability, and uniform temperature distribution. Choosing porous media combustion as the heat source for thermionic power generation can achieve high efficiency and high stability. Furthermore, due to its uniform temperature distribution, based on the principle of thermal expansion and contraction, it can protect the hotspot power generation structure and extend its service life. Attached Figure Description

[0011] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Some specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings in an exemplary and non-limiting manner. The same reference numerals in the drawings indicate the same or similar parts or components. Those skilled in the art should understand that these drawings are not necessarily drawn to scale.

[0012] Figure 1 A schematic diagram of a porous medium combustion coupled thermoelectronic power generation burner device;

[0013] Figure 2 This is a schematic diagram of the load connection for a thermionic power generation structure.

[0014] In the figure, 1-air inlet, 2-gas inlet, 3-gas premixing chamber, 4-airflow distributor, 5-porous medium, 6-thermal electron power generation structure, 7-air preheating channel, 8-porous medium burner wall, 9-cathode, 10-insulation layer, 11-N-type semiconductor, 12-P-type semiconductor. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0016] The main conceptual principle of this invention is as follows: This invention features a porous media burner, a thermionic power generation structure, and an air preheating channel. The air preheating channel is arranged on the outer wall of the thermionic power generation structure. After passing through the preheating channel, air and fuel are separately introduced into the premixing chamber, and after premixing, they enter the porous media burner for ignition and combustion. A stable combustion flame is formed in the porous media, and the combustion heat is transferred away through a combination of radiation heat transfer from the porous media surface and convection heat transfer from the high-temperature flue gas. The thermionic power generation structure is installed on the burner wall, and an external circuit and load are connected for the utilization of combustion waste heat.

[0017] Preferably, the porous medium structure adopts a structure in which the porosity of the lower part is lower than that of the upper part, and the porosity of the porous medium ranges from about 0.25 to 0.95. The porous medium structure is a honeycomb structure, foam structure, or stacked particle structure with uniform pore size and porosity.

[0018] Preferably, the air preheating channel is arranged on the outer wall of the thermionic power generation structure, close to the anode of the thermionic power generation structure, to reduce the anode temperature.

[0019] Preferably, the porous medium burner wall can be designed as a serrated annular wall or a corrugated annular wall.

[0020] Preferably, the thermionic power generation structure consists of a cathode, an insulating layer, an N-type semiconductor, and a P-type semiconductor. The cathode, insulating layer, N-type semiconductor, and P-type semiconductor are all designed with serrated or corrugated annular surfaces, consistent with the design of the porous dielectric burner wall, with the cathode closely attached to the outer wall of the combustion chamber.

[0021] Preferably, an isolation layer is provided between the cathode and the N-type semiconductor, and the cathode and the P-type semiconductor serve as the two poles of the power supply connected to the external load.

[0022] Preferably, the cathode is a high-temperature resistant metal, and the surface can be coated with a low work function material LaB6 to reduce the thermionic emission barrier.

[0023] Preferably, the insulating layer is a high-temperature resistant insulator, such as Al2O3 or SiO2.

[0024] Preferably, the N-type semiconductor is a thin film, such as an InSb thin film doped with group V elements, and the P-type semiconductor is a substrate, such as an InSb substrate.

[0025] The working process of this invention is as follows:

[0026] like Figure 1 As shown, air enters the air preheating channel 7 through the air inlet 1 and, after being fully preheated, enters the premixing chamber 3. Then, the gas is injected into the premixing chamber 3 through the gas inlet 2. In the premixing chamber, the gas is premixed by the rotation effect caused by the jet. After being uniformly rectified by the airflow distributor 4 above, it enters the porous medium 5 in the porous medium burner for stable combustion. The porous medium burner is in the shape of an inverted trapezoid, that is, a trapezoidal structure with a smaller bottom and a larger top. Thermoelectric power generation structure is set on its wall. With the inverted trapezoidal structure, the gas flow rate gradually decreases along the axial cross-sectional area of ​​the burner, the flame propagation speed decreases, the flame stability increases, and the temperature distribution on the wall of the porous medium burner is more stable, which is conducive to the generation of thermoelectrics and improves thermoelectric efficiency.

[0027] During combustion, the heat released by the combustion of gas within the porous medium 5 is rapidly transferred to the surrounding environment through conduction, convection, and radiation, resulting in a lower peak temperature and more uniform temperature distribution within the porous medium combustion zone, thus widening the combustion area. The porous medium downstream of the combustion zone absorbs heat from the flue gas through its own heat storage capacity, recovering waste heat, and then transfers this heat to the porous medium matrix within the combustion zone via radiation and conduction. Within the combustion zone, the heat released by combustion is transferred to the porous medium matrix through convection and a small amount of gas radiation. The porous medium matrix, in turn, transfers this heat upstream of the combustion zone through its own conduction and radiation, heating the fresh premixed fuel gas. Thus, the preheating of the fresh fuel gas, the heat storage and transfer within the porous medium, and the heat release from the combustion zone work together to achieve high-intensity, high-efficiency, and uniform combustion of the fuel gas.

[0028] Part of the heat generated by porous media combustion is transferred to the porous media burner wall through convection, thermal radiation, and thermal conduction of the high-temperature flue gas, and then to the cathode 9, such as... Figure 2 As shown, free electrons in the cathode are thermally heated and then enter the N-type semiconductor 11 via thermionic emission. In the N-type semiconductor, the electrons undergo secondary thermal heating and overcome the NP junction interface barrier to enter the P-type semiconductor 12 via thermoelectric radiation. They then flow through the wires and load back to the cathode, generating electricity. The cathode is made of a high-temperature resistant metal with a low work function material such as LaB6 deposited on its surface to lower the thermionic emission barrier. The N-type semiconductor is an InSb thin film doped with group V elements, and the P-type semiconductor uses an InSb substrate doped with group III elements. The N-type and P-type semiconductors together form the anode. An insulating layer 10 provides electrical and thermal insulation between the cathode and anode, and the distance between the anode and cathode is controlled by the thickness of the insulating layer. To further improve power generation efficiency, a P-type semiconductor can be used as the substrate, and an N-type semiconductor thin film can be deposited on the surface of the P-type semiconductor.

[0029] The above description is only a part of the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the protection scope of the present invention.

Claims

1. A porous medium combustion coupled thermoelectric power generation burner, characterized in that: It includes an air preheating channel, a premixing chamber, an airflow distributor, a porous media burner, and a thermoelectric power generation structure; An air preheating channel is provided around the porous media burner. External air enters the premixing chamber below the porous media burner after passing through the air preheating channel. A gas inlet is opened on one side of the premixing chamber. The gas and preheated air are premixed in the premixing chamber and then enter the porous media burner for combustion through the airflow distributor. A thermoelectric power generation structure is provided on the wall of the porous media burner. The main heat generated by combustion is transferred out through heat transfer via coupled porous media surface radiation and high-temperature flue gas convection. Some of the heat is transferred to the porous media burner wall through high-temperature flue gas convection, thermal radiation, and thermal conduction, and then to the cathode of the thermoelectric power generation structure. The thermoelectric power generation structure uses the combustion waste heat to convert thermal energy into electrical energy. The air preheating channel is located close to the anode in the thermionic power generation structure to reduce the anode temperature.

2. The porous medium combustion coupled thermoelectric power generation burner according to claim 1, characterized in that: The wall surface of the porous medium burner is a sawtooth annular wall surface or a corrugated annular wall surface.

3. The porous medium combustion coupled thermoelectric power generation burner according to claim 2, characterized in that: The aforementioned thermionic power generation structure comprises a cathode, an insulating layer, an N-type semiconductor, and a P-type semiconductor, wherein the N-type semiconductor and the P-type semiconductor constitute the anode of the thermionic power generation structure.

4. The porous medium combustion coupled thermoelectric power generation burner according to claim 1, characterized in that: The porous media burner has an inverted trapezoidal structure.

5. The porous medium combustion coupled thermoelectric power generation burner according to claim 4, characterized in that: The porous media structure in the porous media burner adopts a structure with low porosity at the bottom and high porosity at the top, and the porosity of the porous media ranges from 0.25 to 0.

95.

6. The porous medium combustion coupled thermoelectric power generation burner according to claim 1, characterized in that: The porous media structure is a honeycomb structure, foam structure, or stacked particle structure with uniform pore size and porosity.

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