A miniature pulsed burner for gaseous fuels

Abstract

This invention relates to a micro-pulsating burner for gaseous fuels, comprising a micro-burner, an air intake pipe, a gas intake pipe, an electric spark hexagonal nut, and an outer electrode for the electric spark. The micro-burner consists of a front cover, a cylindrical combustion chamber, and a tailpipe. Gaseous fuel is introduced into the combustion chamber through the gas intake pipe and, under electric spark ignition, mixes and burns with air introduced through the air intake pipe. The resulting high-temperature, high-pressure gas is ejected from the tailpipe. The micro-pulsating burner of this invention offers advantages such as stable combustion position, complete combustion, reliable pulsed combustion, fast combustion speed, short combustion time, high intensity, low heat loss, and high thermal efficiency, making it promising for application in micro-energy systems.

Description

Technical Field

[0001] This invention belongs to the field of pulsed combustion technology, and relates to pulsed burners, particularly to a micro pulsed burner for gaseous fuels. Background Technology

[0002] With technological advancements and industry demands, microdevices and systems such as micromedical devices, sensors, micromotors, micropumps, and micro unmanned aerial vehicles are widely used in medical, industrial, defense, and scientific research fields. These microdevices all require energy supply systems—micro-energy systems—and these systems are required to be small in size, lightweight, high in energy density, and long in duration.

[0003] As a core component of micro-energy systems, micro-burners present certain challenges in design and development. Due to size limitations, micro-burners suffer from very small effective combustion space, difficulties in fuel mixing during stable combustion, and short fuel residence time. Furthermore, improper design can lead to increased heat loss, resulting in unstable combustion, low combustion efficiency, and low thermal efficiency. To further optimize stable combustion at the microscale, Chinese patent document CN201407654Y proposes a novel gas turbine burner that employs gas preheating. Its combustion chamber is located within the air inlet, and part of the combustion chamber wall is porous.

[0004] Traditional micro-burners are mostly based on continuous fuel combustion. However, continuous combustion has problems such as low combustion intensity and low combustion efficiency. Even with certain improvements, the improvement in the combustion efficiency of micro-burners remains limited.

[0005] Pulsed combustion is a combustion mode between continuous combustion and explosive combustion, characterized by self-excited oscillatory combustion under specific burner structures. It differs from conventional steady-state combustion devices in that parameters such as pressure, temperature, flow rate, and heat release rate within the pulsed combustion zone change periodically over time. Compared to continuous combustion, pulsed burners offer higher combustion intensity, heat transfer efficiency, and overall thermal efficiency, while exhibiting lower pollutant emissions. Furthermore, pulsed burners offer advantages such as simple structure, no moving parts, and ease of processing and assembly. Compared to steady-state continuous combustion, pulsed combustion has significant advantages when applied to micro-burners, saving structural materials, fuel, and reducing pollution.

[0006] The inventors of this patent application have been engaged in the research and development of pulsed burners. They previously published an invention patent with the publication number CN202660550U entitled "An Invention Patent for a Micro Pulsating Burner" and were granted the invention patent. This patent adopts a Rick-type pulsed burner structure design, which enables the gas to burn stably at 1L / 4 of the burner, thereby stimulating pulsed combustion.

[0007] However, micro-burners based on steady-state continuous combustion mode suffer from insufficient power and high heat loss. This invention applies pulsed combustion technology to micro-burners and proposes a micro-pulsated burner that solves problems such as short fuel residence time, insufficient combustion intensity, high heat loss, and low thermal efficiency. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a micro-pulsating burner for gaseous fuels, which has a fast combustion speed, high combustion intensity, high thermal efficiency and low heat loss.

[0009] The technical problem solved by this invention is achieved through the following technical solution:

[0010] A micro-pulsating burner for gaseous fuels, characterized in that it comprises a gas inlet pipe, an air inlet pipe, a micro-burner, and a tailpipe. The micro-burner consists of a front cover, a combustion chamber, and a tailpipe. The front section of the micro-burner is a solid front cover. The middle section of the micro-burner is a combustion chamber composed of a cylinder and a frustum connected in sequence. The combustion chamber is threadedly connected to the front cover. The tailpipe is the rear end of the micro-burner. A hexagonal nut for electric spark and the gas inlet pipe are arranged at a 90° angle on the side wall of the cylindrical section of the combustion chamber. A hexagonal nut for electric spark and an outer electrode for electric spark are arranged at a 180° angle on the side wall of the cylindrical section of the combustion chamber. The air inlet pipe is threadedly connected and parallel to the tailpipe on both sides of the frustum of the combustion chamber.

[0011] Furthermore, the micro-burner is a high-temperature resistant hollow tube made of 304 stainless steel. The combustion chamber has an inner diameter of 20-30 mm, a wall thickness of 2-3 mm, and a length of 20-30 mm. The tailpipe is a hollow cylindrical tailpipe with an inner diameter of 4-6 mm, a wall thickness of 1-2 mm, and a length of 50-70 mm.

[0012] Furthermore, the length of the air intake pipe is 10-20 mm, the outer diameter is 3-4 mm, and the wall thickness is 1-2 mm; the length of the gas intake pipe is 10-20 mm, the outer diameter is 4-6 mm, and the wall thickness is 1-2 mm.

[0013] Furthermore, the outer electrode of the electrical discharge machining (EDM) is a bolt composed of a threaded section and a smooth section. The outer diameter of the threaded section is 4–8 mm and the length is 5–10 mm. The outer diameter of the smooth section is 1–2 mm and the length is 15–20 mm. The hexagonal nut of the EDM is composed of a hollow cylinder and a hexagonal nut. The outer diameter of the hollow cylinder is 4–8 mm and the inner diameter is 3–4 mm. The outer side of the hollow cylinder is provided with external threads. The hollow cylinder is connected to the combustion chamber through the external threads. The inner diameter of the hexagonal nut is 10–20 mm and the thickness is 1–2 mm. The inner side of the hexagonal nut is provided with internal threads. The hexagonal nut is connected to the external EDM through the internal threads.

[0014] The advantages and beneficial effects of this invention are as follows:

[0015] 1. This invention relates to a micro-pulsating burner for gaseous fuels. The main structure of the micro-burner has no moving parts, resulting in a simple structure, stable combustion position, and reliable pulsed combustion. The pulsed combustion mode generates strong pulsations in the airflow within the combustion chamber, greatly enhancing the mixing degree of the gas and air and improving heat and mass transfer, thus increasing the combustion intensity. The pulsation effect increases the impact intensity between the flue gas and the pipe wall, reducing the resistance to heat transfer and thereby improving the heat transfer coefficient.

[0016] 2. The micro-pulsating burner for gaseous fuels of the present invention has a simple structure and small size, which greatly reduces production investment and manufacturing costs. Due to the characteristics of pulsed combustion, it saves fuel and thus saves operating costs. Under the micro-characteristics of the micro-pulsating burner, it can be applied to micro-energy systems, improving their endurance, service life and response efficiency. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention;

[0018] Figure 2 This is the front view of the present invention;

[0019] Figure 3 for Figure 2 Sectional view along A to A.

[0020] Explanation of reference numerals in the attached figures

[0021] 1-Gas intake pipe, 2-Combustion chamber, 3-Air intake pipe, 4-Tailpipe, 5-Electrical spark hexagonal nut, 6-Front cover, 7-Micro burner, 8-Outer electrode of electrical spark. Detailed Implementation

[0022] The present invention will be further described in detail below through specific embodiments. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0023] like Figure 1 As shown, a micro-pulsating burner for gaseous fuels is innovative in that it consists of a micro-burner 7, an air intake pipe 3, a gas intake pipe 1, an electric spark hexagonal nut 5, and an electric spark outer electrode 8. The micro-burner 7 is a hollow tube made of 304 stainless steel and is placed horizontally during use.

[0024] The micro-burner 7 consists of a front cover 6, a combustion chamber 2, and a tailpipe 4. The front cover 6 and the combustion chamber 2 are tightly connected by threads. The diameter of the front cover, to which the combustion chamber 2 of the micro-burner 7 is connected by threads, is 15-25 mm. The inner diameter of the combustion chamber 2 is 20-30 mm, the wall thickness is 2-3 mm, and the length is 20-30 mm. The tailpipe of the micro-burner has an inner diameter of 4-6 mm, a wall thickness of 1-2 mm, a length of 50-70 mm, and an external thread of 10-20 mm at the outlet for easy connection to various external equipment.

[0025] The electric spark hexagonal nut 5 of the present invention is connected at one end to the interface reserved in the combustion chamber and at the other end to the external ignition device; the gas intake pipe 1 of the present invention is connected at one end to the air inlet reserved in the combustion chamber and at the other end to the external gas device; the air intake pipe 1 of the present invention is connected at one end to the air inlet reserved in the combustion chamber and at the other end to the micro air pump.

[0026] like Figure 2 The gas intake pipe 1 is a hollow stainless steel round tube with external threads, with an outer diameter of 5-10 mm, a thickness of 1-2 mm, and a length of 10-20 mm. The air intake pipe 3 is a hollow stainless steel round tube with external threads, with an outer diameter of 3-5 mm, a thickness of 1-2 mm, and a length of 10-20 mm. The outer electrode 8 of the electric spark electrode consists of a bolt with external threads (outer diameter 4-6 mm, length 5-10 mm) and a smooth bolt (outer diameter 1-2 mm, length 10-20 mm). The electric spark hexagonal nut 5 consists of a hollow cylinder with external threads (outer diameter 5-6 mm, inner diameter 3-4 mm, length 5-8 mm) at the combustion chamber end and a hexagonal nut with internal threads (inner diameter 10-15 mm, thickness 1-2 mm) at the electric spark end.

[0027] like Figure 3 The combustion chamber 2 has a gas inlet and an external EDM electrode inlet, both of which are hollow cylinders with a protrusion of 5-10 mm in height and a diameter of 4-6 mm. The EDM hexagonal nut inlet has a diameter of 4-6 mm, and the air inlet 3 has a diameter of 3-4 mm. The gas inlet pipe 1 and the gas inlet are tightly connected together by threads, as are the air inlet pipe 3 and the air inlet. The EDM hexagonal nut 5 is tightly connected to the EDM hexagonal nut inlet by threads.

[0028] The working principle of this invention is as follows:

[0029] When the micro-pulsating burner of the present invention is working, the gas and air enter the combustion chamber 2 of the micro-burner 7 through the gas inlet pipe 1 and the air inlet pipe 3 respectively to form a mixed gas. Under the operation of the ignition device, the mixed gas forms a stable pulsating combustion in the combustion chamber, which causes the temperature and pressure of the gas flow to rise sharply. When a certain level is reached, the gas flow spreads from the combustion chamber to the tailpipe, forming a high-temperature and high-frequency oscillating tail gas flow.

[0030] This miniature pulsed burner is designed based on the acoustic Helmholtz resonator. Compared to traditional valved pulsed burners, it eliminates the inlet check valve, replacing it with a premixing chamber closed at one end. During operation, the closed end of the premixing chamber reflects the combustion waves generated during combustion, serving the same function as the inlet check valve. The incident and reflected waves superimpose during burner operation. Simultaneously, the heat released during combustion causes a pressure increase. When this pressure increase and pressure pulsation are in phase, the pressure oscillation within the combustion chamber intensifies, thus exciting combustion.

[0031] Although embodiments and drawings of the present invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A micro pulsating combustor for gaseous fuel, characterized by: The device includes a gas intake pipe (1), an air intake pipe (3), a micro burner (7), and a tailpipe (4). The micro burner (7) consists of a front cover (6), a combustion chamber (2), and a tailpipe (4). The front section of the micro burner (7) is a solid front cover (6). The middle section of the micro burner (7) is a combustion chamber (2) composed of a cylinder and a frustum connected in sequence. The combustion chamber (2) is threadedly connected to the front cover (6). The tail of the micro burner (7) is the tailpipe (4). The cylindrical section of the combustion chamber (2) is provided with an electric spark hexagonal nut (5) and the gas intake pipe (1) at a 90° angle on the side wall. The cylindrical section of the combustion chamber (2) is provided with an electric spark hexagonal nut (5) and an electric spark outer electrode (8) at a 180° angle on the side wall. The air intake pipe (3) is threadedly connected and parallel to the tailpipe (4) on both sides of the frustum of the combustion chamber (2). One end of the electric spark hexagonal nut (5) is connected to the interface reserved in the combustion chamber, and the other end is connected to the external ignition device; The micro-pulsating burner is designed based on the acoustic Helmholtz resonator and uses a premixing chamber that is closed at one end. During operation, the closed end of the premixing chamber is used to reflect the combustion waves generated during combustion, which has the same function as the inlet check valve. When the burner is working, the incident wave and the reflected wave will superimpose. At the same time, the combustion heat will cause the pressure to rise. When the pressure rise caused by the combustion heat is in phase with the pressure pulsation, the pressure oscillation in the combustion chamber will be strengthened, and the combustion will be excited.

2. The micro pulsating combustor for gaseous fuel according to claim 1, characterized by: The micro burner (7) is a high-temperature resistant hollow tube made of 304 stainless steel. The combustion chamber (2) has an inner diameter of 20-30 mm, a wall thickness of 2-3 mm, and a length of 20-30 mm. The tail tube (4) is a hollow cylindrical tail tube with an inner diameter of 4-6 mm, a wall thickness of 1-2 mm, and a length of 50-70 mm.

3. The micro pulsating combustor for gaseous fuel according to claim 1, characterized by: The length of the air intake pipe (3) is 10-20 mm, the outer diameter is 3-4 mm, and the wall thickness is 1-2 mm; the length of the gas intake pipe (1) is 10-20 mm, the outer diameter is 4-6 mm, and the wall thickness is 1-2 mm.

4. The micro pulsating combustor for gaseous fuel according to claim 1, characterized by: The outer electrode (8) of the electric spark is a bolt composed of a threaded section and a smooth section. The outer diameter of the threaded section is 4-8 mm and the length is 5-10 mm. The outer diameter of the smooth section is 1-2 mm and the length is 15-20 mm. The electric spark hexagonal nut (5) is composed of a hollow cylinder and a hexagonal nut. The outer diameter of the hollow cylinder is 4-8 mm and the inner diameter is 3-4 mm. The outer side of the hollow cylinder is provided with an external thread. The hollow cylinder is connected to the combustion chamber (2) through the external thread. The inner diameter of the hexagonal nut is 10-20 mm and the thickness is 1-2 mm. The inner side of the hexagonal nut is provided with an internal thread. The hexagonal nut is connected to the external electric spark through the internal thread.

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