A porous medium nozzle for liquid fuel gasification

Abstract

A porous medium nozzle for liquid fuel gasification disclosed by the present invention belongs to the fields of combustion and power devices. The present invention includes a nozzle base, a porous medium, and an end cap. The interior of the nozzle base has a capillary liquid delivery tube, a liquid collection cavity, an air orifice plate, a fuel inlet, and an air inlet. The present invention adopts multiple capillary liquid delivery tubes to reduce the cross-sectional area of a single channel, preventing large fluctuations in the liquid level and fluctuations in the evaporation rate when the fuel boils; flexibly changing the number of capillary liquid delivery tubes according to the flow rate requirement, and the coaxial air can significantly improve the evaporation rate of the liquid fuel, avoiding safety risks caused by fuel accumulation; the capillary liquid delivery tubes of the liquid fuel are inserted into the porous medium, and the flame quenching effect of the porous medium keeps the flame away from the fuel nozzle, which can not only prevent the coking problem and unstable evaporation problem caused by overheating of the liquid delivery tube, but also realize the re-combustion after the fuel is mixed with air, improve the combustion efficiency, reduce the generation of pollutants such as soot, and contribute to achieving clean and efficient combustion.

Description

Technical Field

[0001] The present invention belongs to the fields of combustion and power devices, and relates to a porous medium nozzle for gasifying liquid fuel. Background Art

[0002] In recent years, the progress of microfabrication technology has promoted the rapid development of micro-miniature devices, and their applications involve aerospace (small unmanned aerial vehicles, micro-nano satellites, etc.), military fields (individual combat systems, etc.), wireless communication and computing (smartphones, laptops), etc. Micro-power systems with high energy density and long endurance time have become one of the key components to improve the performance of devices. Using the combustion of hydrocarbon fuels as a power source in micro-miniature power systems has broad development prospects.

[0003] To achieve efficient and stable combustion of liquid fuel, it is necessary to ensure a stable and sufficient fuel evaporation rate. Due to the small fuel flow rate of micro-miniature burners and the need for sufficient space for jet development, conventional atomizers are not suitable for micro-scale combustion, and evaporation-type fuel nozzles are usually used. However, when the evaporation-type nozzle overheats, the evaporation rate will fluctuate greatly and fuel carbonization and coking will occur, resulting in flame oscillation and structural damage; the insufficient mixing distance between fuel and air in the micro-combustion chamber leads to a large amount of soot generated during combustion. Summary of the Invention

[0004] To solve the problems such as large oscillation of evaporation rate, coking of fuel nozzles, and high soot emissions during the combustion of liquid fuel, the main object of the present invention is to provide a porous medium nozzle for gasifying liquid fuel, which can be used in a working environment with a wide temperature range and a large adjustment ratio, and achieve clean, efficient, and stable combustion of liquid fuel. The present invention can not only be used in micro-combustors, but also flexibly change the number of capillary infusion tubes according to the flow rate and combustion power requirements, and be used in large and medium-sized combustors.

[0005] The object of the present invention is achieved by the following technical solutions:

[0006] A porous medium nozzle for gasifying liquid fuel disclosed by the present invention includes a porous medium, an end cap, and a nozzle base.

[0007] The nozzle base internally has capillary infusion tubes, an air orifice plate, an air inlet, a liquid collection chamber, and a fuel inlet. The nozzle base is integrally manufactured by 3D printing technology, or assembled by screwing after manufacturing parts. Preferably, the nozzle base is integrally manufactured by 3D printing technology.

[0008] The fuel nozzle uses multiple capillary infusion tubes, and the number of capillary infusion tubes can be flexibly changed according to the flow rate requirement. After passing through the air orifice plate, part of the capillary infusion tubes are inserted into the porous medium, and the distance between the tube orifice and the surface of the porous medium is adjusted according to the fuel gasification difficulty and the requirement of fuel-air mixing degree.

[0009] Preferably, the fuel nozzle uses a multi-channel capillary infusion tube with a diameter less than 1 mm.

[0010] An air orifice plate is used to generate an air flow in the same direction as the fuel flow, i.e., coaxial air. The number and position of the ventilation holes on the orifice plate are the same as those of the infusion tube, and the orifice diameter is larger than the outer diameter of the infusion tube.

[0011] The end cap and the nozzle base are connected by threads. After the end cap is tightened, it can compress the porous medium. The nozzle base and the fuel pipeline are connected by threads.

[0012] The porous medium is cylindrical in shape, and a circular blind hole is machined at the bottom end. The number of circular holes is the same as the number of capillary infusion tubes, the positions of the circular holes correspond one-to-one with the capillary infusion tubes, and the diameter of the circular holes is equal to the outer diameter of the infusion tube.

[0013] Preferably, the materials of the nozzle base and the end cap are metal or ceramic, and the porous medium is made of foam ceramic, foam metal, powder sintered metal, particle-packed porous medium or metal wire mesh.

[0014] A working method of a porous medium nozzle for liquid fuel gasification disclosed by the present invention is as follows:

[0015] The nozzle base is connected to the fuel pipeline by threads. The fuel nozzle uses a multi-channel capillary infusion tube to reduce the cross-sectional area of a single channel, prevent large oscillations of the liquid level and fluctuations in the evaporation rate when the fuel boils, and improve combustion stability; the fuel nozzle can flexibly change the number of capillary infusion tubes according to the flow rate requirement. The coaxial air can significantly increase the evaporation rate of the liquid fuel, ensure complete evaporation of the liquid fuel, and avoid safety risks caused by fuel accumulation; the fuel enters the porous medium through the fuel inlet, the liquid collection cavity and the capillary infusion tube. The flame quenching effect of the porous medium keeps the flame away from the fuel nozzle opening. The air enters the nozzle through the air inlet, and after being rectified by the air orifice plate, the flow direction is the same as that of the fuel and the air flow surrounds the infusion tube; the liquid fuel undergoes a phase change and gasification in the infusion tube and the porous medium, and is mixed with the air in the porous medium and then burns downstream of the porous medium. This can not only prevent coking problems and unstable evaporation problems caused by overheating of the infusion tube, but also realize re-combustion after fuel and air are premixed, effectively improve the combustion efficiency, reduce soot generation, and contribute to achieving clean and efficient combustion.

[0016] Advantageous effects:

[0017] 1. The porous medium nozzle for liquid fuel gasification disclosed by the present invention has a compact structure and strong applicability. When the nozzle works, it does not require conditions such as high-pressure air to assist fuel atomization. It can flexibly change the number of capillary infusion tubes according to the flow rate and combustion power requirements, achieving a large adjustment ratio of the burner power. It can be used for both micro-burners and large and medium-sized burners.

[0018] 2. A porous medium nozzle for liquid fuel gasification disclosed by the present invention adopts a combination of multiple capillary infusion tubes, coaxial air, and porous medium, and can achieve stable evaporation of liquid fuel within a wide temperature range. When the temperature of the capillary infusion tube is higher than the boiling point of the fuel, the liquid fuel boils in the capillary. Due to the small diameter of the infusion tube, the oscillation amplitude of the gas-liquid interface is small, and stable evaporation can be achieved. When the temperature of the capillary infusion tube is lower than the boiling point of the fuel, the liquid fuel flows out of the capillary and spreads on the surface of the porous medium skeleton, and the large specific surface area of the porous medium is used to increase the evaporation surface area. An air orifice plate is used to form coaxial air flow, and the evaporation convection strengthening effect is utilized to achieve complete evaporation of the liquid fuel.

[0019] 3. A porous medium nozzle for liquid fuel gasification disclosed by the present invention utilizes the flame quenching effect of the porous medium to isolate the flame and the fuel outlet, and can prevent fuel carbonization and coking caused by too high temperature at the outlet of the infusion tube. At the same time, the fuel is mixed with air in the porous medium and then burns downstream of the porous medium, which can reduce soot generation and contribute to achieving clean and efficient combustion. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of a porous medium nozzle for liquid fuel gasification;

[0021] Figure 2 is a cross-sectional view of the porous medium nozzle;

[0022] Figure 3 is a cross-sectional view of the nozzle base;

[0023] Figure 4 is a cross-sectional view of the A-A section of the nozzle base.

[0024] Description of the reference numerals: 1 - end cap, 2 - porous medium, 3 - nozzle base, 4 - capillary infusion tube, 5 - air orifice plate, 6 - air inlet, 7 - liquid collection chamber, 8 - bottom thread, 9 - fuel inlet, 10 - top thread. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] In order to better illustrate the purpose and advantages of the present invention, the following further describes the content of the invention with reference to the drawings and examples.

[0026] Example 1:

[0027] A porous medium nozzle for liquid fuel gasification disclosed in this example is composed of an end cap 1, a porous medium 2, and a nozzle base 3. The inside of the nozzle base is composed of a capillary infusion tube 4, an air orifice plate 5, an air inlet 6, a liquid collection chamber 7, and a fuel inlet 9.

[0028] The nozzle base 3 is integrally manufactured using 3D printing technology, and the material is nickel-based high-temperature resistant alloy; the porous medium 2 is a foam stainless steel with a pore density of 100 ppi. During assembly, first place the porous medium 2 into the nozzle base 3, and the end cap 1 is threadedly connected to the nozzle base 3. After the end cap is tightened, it can compress the porous medium. The nozzle base has four capillary infusion tubes with an inner diameter of 0.5 mm and an outer diameter of 1 mm. After the capillary infusion tubes pass through the air orifice plate, part of them is inserted into the porous medium, and the tube orifice is located in the middle of the porous medium.

[0029] During use, the nozzle base is connected to the fuel pipeline through the thread 10, and the fuel enters the porous medium through the fuel inlet 9, the liquid collection cavity 7, and the capillary infusion tubes 4; the air enters the nozzle through the air inlet 6, and after being rectified by the air orifice plate 5, the flow direction is the same as that of the fuel and the air flow surrounds the infusion tubes; the liquid fuel undergoes phase change and gasification in the infusion tubes and the porous medium, and the fuel and air are mixed in the porous medium and then burned downstream of the porous medium.

[0030] The above specific description further details the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above is only a specific embodiment of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A porous medium nozzle for liquid fuel gasification, characterized in that: It includes a porous medium, an end cap, and a nozzle base; Inside the nozzle base, there are capillary infusion tubes, an air orifice plate, an air inlet, a liquid collection chamber, and a fuel inlet; The porous medium nozzle adopts multiple capillary infusion tubes and can flexibly change the number of capillary infusion tubes according to the flow rate requirement; after passing through the air orifice plate, part of the capillary infusion tubes are inserted into the porous medium, and the distance between the tube orifice and the surface of the porous medium is adjusted according to the gasification difficulty of the liquid fuel and the requirement of the liquid fuel-air mixing degree; The air orifice plate is used to generate an air flow in the same direction as the liquid fuel flow, that is, coaxial air; the number and position of the ventilation holes on the air orifice plate are the same as those of the capillary infusion tubes, and the aperture is larger than the outer diameter of the capillary infusion tubes; The end cap is connected to the nozzle base by a thread, and the porous medium can be tightly pressed after the end cap is tightened; the nozzle base is connected to the fuel pipeline by a thread; The outer shape of the porous medium is cylindrical, and circular blind holes are processed at the bottom end. The number of circular blind holes is the same as the number of capillary infusion tubes, and the positions of the circular blind holes correspond to those of the capillary infusion tubes one by one. The diameter of the circular blind holes is equal to the outer diameter of the capillary infusion tubes; The inner diameter of the capillary infusion tube is 0.5 mm, and the outer diameter is 1 mm; The materials of the nozzle base and the end cap are metal or ceramic, and the porous medium adopts foam ceramics, foam metals, powder sintered metals, particle-packed porous media, or metal wire meshes.

2. The porous medium nozzle for liquid fuel gasification according to claim 1, characterized in that: The nozzle base is integrally manufactured by 3D printing technology.

3. A porous medium nozzle for liquid fuel gasification according to claim 1 or 2, characterized in that: The nozzle base is connected to the fuel pipeline by a thread. The porous medium nozzle adopts multiple capillary infusion tubes to reduce the cross-sectional area of a single channel, prevent large fluctuations in the liquid level and fluctuations in the evaporation rate when the liquid fuel boils, and improve the combustion stability; the number of capillary infusion tubes can be flexibly changed according to the flow rate requirement. The coaxial air can significantly increase the evaporation rate of the liquid fuel, ensure the complete evaporation of the liquid fuel, and avoid the safety risks caused by the accumulation of the liquid fuel; the liquid fuel enters the porous medium through the fuel inlet, the liquid collection chamber, and the capillary infusion tubes. The flame quenching effect of the porous medium makes the flame away from the fuel tube orifice. The air enters the porous medium nozzle through the air inlet, and after being rectified by the air orifice plate, the flow direction is the same as that of the liquid fuel and the air flow surrounds the capillary infusion tubes; the liquid fuel undergoes a phase change and gasification in the capillary infusion tubes and the porous medium, and the liquid fuel and the air are mixed in the porous medium and then burned downstream of the porous medium. This can not only prevent the coking problem and unstable evaporation problem caused by overheating of the capillary infusion tubes, but also realize the combustion after the liquid fuel and the air are mixed, effectively improve the combustion efficiency, reduce the soot generation, and contribute to the realization of clean and efficient combustion.

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