CN108644765B - Miniature liquid burner capable of reducing wet wall effect and combustion method thereof - Google Patents
Miniature liquid burner capable of reducing wet wall effect and combustion method thereof Download PDFInfo
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- CN108644765B CN108644765B CN201810535415.7A CN201810535415A CN108644765B CN 108644765 B CN108644765 B CN 108644765B CN 201810535415 A CN201810535415 A CN 201810535415A CN 108644765 B CN108644765 B CN 108644765B
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- 239000007788 liquid Substances 0.000 title claims abstract description 40
- 230000000694 effects Effects 0.000 title claims abstract description 22
- 238000009841 combustion method Methods 0.000 title abstract description 7
- 238000002485 combustion reaction Methods 0.000 claims abstract description 81
- 230000002093 peripheral effect Effects 0.000 claims abstract description 4
- 239000000446 fuel Substances 0.000 claims description 42
- 229910052751 metal Inorganic materials 0.000 claims description 24
- 239000002184 metal Substances 0.000 claims description 24
- 230000009471 action Effects 0.000 claims description 13
- 230000007704 transition Effects 0.000 claims description 12
- 238000000034 method Methods 0.000 claims description 10
- 239000004215 Carbon black (E152) Substances 0.000 claims description 9
- 229930195733 hydrocarbon Natural products 0.000 claims description 9
- 150000002430 hydrocarbons Chemical class 0.000 claims description 9
- 230000008569 process Effects 0.000 claims description 8
- 230000005684 electric field Effects 0.000 claims description 7
- 238000009736 wetting Methods 0.000 claims description 5
- 230000001154 acute effect Effects 0.000 claims description 4
- 230000002035 prolonged effect Effects 0.000 claims description 4
- 239000003595 mist Substances 0.000 claims description 3
- 238000007789 sealing Methods 0.000 claims description 3
- 238000000889 atomisation Methods 0.000 abstract description 6
- 239000007789 gas Substances 0.000 description 35
- 239000000463 material Substances 0.000 description 10
- 238000011160 research Methods 0.000 description 6
- 238000001704 evaporation Methods 0.000 description 5
- 230000008020 evaporation Effects 0.000 description 5
- 239000000919 ceramic Substances 0.000 description 3
- 239000007921 spray Substances 0.000 description 3
- 238000005507 spraying Methods 0.000 description 3
- 239000010935 stainless steel Substances 0.000 description 3
- 229910001220 stainless steel Inorganic materials 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000009825 accumulation Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000035699 permeability Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000010992 reflux Methods 0.000 description 2
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 2
- 229910010271 silicon carbide Inorganic materials 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 229910052729 chemical element Inorganic materials 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 238000005459 micromachining Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000009423 ventilation Methods 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D11/00—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space
- F23D11/10—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space the spraying being induced by a gaseous medium, e.g. water vapour
- F23D11/22—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space the spraying being induced by a gaseous medium, e.g. water vapour the gaseous medium being vaporised fuel, e.g. for a soldering lamp, or other gaseous fuel
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D11/00—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space
- F23D11/36—Details, e.g. burner cooling means, noise reduction means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D11/00—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space
- F23D11/36—Details, e.g. burner cooling means, noise reduction means
- F23D11/38—Nozzles; Cleaning devices therefor
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D11/00—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space
- F23D11/36—Details, e.g. burner cooling means, noise reduction means
- F23D11/44—Preheating devices; Vaporising devices
- F23D11/441—Vaporising devices incorporated with burners
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Spray-Type Burners (AREA)
Abstract
The invention discloses a miniature liquid burner for reducing wet wall effect and a combustion method thereof; the burner mainly comprises an upper cover plate, a lower cover plate, an inner sleeve, an outer sleeve, a combustion chamber, a conical atomizing chamber and the like. A plurality of symmetrically distributed air inlet cuts are tangentially arranged along the peripheral wall surface of the conical atomizing chamber; a plurality of air inlet pipelines penetrate through the outer sleeve and the inner sleeve and are communicated with the air cavity; outside air is introduced into the air cavity through the air inlet pipeline, then moves along the inner wall surface of the conical atomizing chamber in a rotational flow mode through the air inlet notch, and forms a layer of air film on the inner wall surface of the conical atomizing chamber so as to reduce the wet wall effect of charged atomization of liquid in the atomizing chamber. Meanwhile, part of the tail gas is recycled, the air is preheated, the burner is insulated, heat loss is reduced, and combustion efficiency is improved.
Description
Technical Field
The invention relates to a combustion device, in particular to a miniature liquid burner capable of reducing a wet wall effect and a combustion method thereof.
Background
In recent decades, with the rapid development of MEMS micromachining technology and urgent needs in both military and civilian use, various microminiature aircrafts and portable electronic devices have been continuously emerging. Currently, most miniature devices and systems are powered by conventional chemical batteries. However, the chemical battery has the defects of low energy density, large volume and weight, short service time, long charging time and the like, and is insufficient to meet the requirement of the micro power equipment on the cruising ability. The energy density of the liquid hydrocarbon fuel can reach tens times as high as that of the best lithium battery at present, and meanwhile, the liquid hydrocarbon fuel belongs to an environment-friendly fuel relative to a chemical battery, so researchers gradually shift research emphasis to the research of a micro energy system. Among them, designing a micro burner with excellent performance has been a research hotspot of researchers.
Unlike conventional combustion processes, microscale combustion still faces many challenges at the present stage. The reduction in size of the microcombustor results in a greatly shortened residence time of fuel and air in the burner, insufficient combustion of the fuel, and failure of smooth combustion. Meanwhile, the heat dissipation loss caused by the increase of the surface-to-volume ratio is remarkable, and the problems of material limitation, quenching of chemical element wall surfaces and the like are not negligible. Therefore, achieving stable combustion and improving combustion efficiency in a minute scale are important points of research today. However, the microcombustors that have been currently implemented mostly use gaseous fuels, which have low energy density, are inconvenient to store and transport, and have explosion hazards, compared to liquid fuels, so that they have low practicality. It is envisioned that liquid hydrocarbon fuels will become the primary fuel for future microcombutors.
However, the evaporation of the liquid fuel requires additional time and space, and the structural design of the burner thereby presents a significant challenge. Compared with the mechanical evaporation of liquid, the charged spray technology is adopted, so that the size of fog drops is smaller, the evaporation and mixing speed is increased, a good atomization effect is achieved, and meanwhile, an atomization flow field can be adjusted by adjusting electric parameters, so that the control is convenient, and spray combustion becomes a research hot spot at home and abroad at present. In particular, in recent years, a group of professor Gan Yunhua, university of south China, has conducted extensive research and has made a number of outstanding contributions to liquid charged atomization. However, the difficult problem still exists, and the wall surface is easy to adsorb liquid drops in the charged spraying process due to the reduction of the size of the burner, so that the phenomenon of wetting the wall is serious. Therefore, there is a need to provide a miniaturized liquid burner that is more structurally sound in view of the above problems.
Disclosure of Invention
The invention aims to overcome the defects and shortcomings of the prior art, and provides a miniature liquid burner capable of reducing the wet wall effect and a combustion method thereof, so as to solve the technical problems of serious wet wall phenomenon, low fuel utilization rate, short mixed gas residence time, uneven combustion temperature distribution and the like when liquid hydrocarbon fuel adopts a charged spraying method under the microscale of the burner.
The invention is realized by the following technical scheme:
a miniature liquid burner for reducing wet wall effect, comprising an outer sleeve 2, an inner sleeve 3 and a combustion chamber 13 arranged at the upper part in the inner sleeve 3; the outer sleeve 2 and the inner sleeve 3 are sleeved with each other, the lower ends of the outer sleeve 2 and the inner sleeve 3 are fixed on the lower cover plate 6 in a sealing way, and the upper end of the outer sleeve 2 is sealed by the upper cover plate 1; the lower cover plate 6 is provided with a fuel nozzle 7; the outer sleeve 2 and the inner sleeve 3 are mutually spaced and form an exhaust gas discharge channel; a gap 15 is reserved between the upper end of the inner sleeve 3 and the upper cover plate 1, and the upper port of the inner sleeve 3 is sealed with the outer edge of the combustion chamber 13; the tail gas after combustion in the combustion chamber 13 is sequentially discharged from a gap 15 at the upper end of the inner sleeve 3, a tail gas discharge channel and a tail gas discharge port 8 arranged at the lower end of the outer sleeve 2;
a conical atomizing chamber 5 with a small upper part and a large lower part which are butted with the bottom of the combustion chamber 13 is arranged in the inner sleeve 3 and on the lower cover plate 6; a metal grid 10 and a porous medium disc 11 are sequentially arranged at the top of the conical atomizing chamber 5;
the outer wall of the conical atomizing chamber 5 and the space between the outer wall of the combustion chamber 13 and the inner wall of the inner sleeve 3 form an air chamber 16;
a plurality of symmetrically distributed air inlet cuts 9 are tangentially arranged along the peripheral wall surface of the conical atomizing chamber 5; a plurality of air inlet pipes 4 penetrate through the outer sleeve 2 and the inner sleeve 3 and are communicated with the air cavity 16; the external air is introduced into the air cavity 16 through the air inlet pipeline 4, then moves along the inner wall surface of the conical atomizing chamber 5 in a rotational flow mode through the air inlet notch 9, and forms a layer of air film on the inner wall surface of the conical atomizing chamber 5.
The inner cavity of the combustion chamber 13 is divided into an upper cavity and a lower cavity, the diameter of the upper cavity is smaller than that of the lower cavity, and the joint transition part of the upper cavity and the lower cavity is a right-angle transition; the right angle transition forms an inner step 17.
The internal diameter of the combustion chamber 13 is greater than the internal diameter of the top of the conical atomizing chamber 5; the combustion chamber 13 and the conical atomizing chamber 5 are combined to form a venturi structure; the wall surface of the conical atomizing chamber 5 and the lower cover plate 6 form an acute angle of 78-82 degrees.
The outlet positions of the air inlet pipelines 4 respectively correspond to the inlets of the air inlet notches 9;
the air inlet notch 9 is a strip-shaped vertical notch, and the outlet position of each air inlet pipeline 4 is positioned in the middle of the strip-shaped vertical notch.
The fuel nozzle 7 penetrates the lower cover plate 6 and extends into the conical atomizing chamber 5, and is positioned in the middle of the conical atomizing chamber 5.
An igniter 12 is provided above the side of the porous medium disc 11, and the igniter 12 is connected to an external power source through a wire 14.
The distance between the upper end of the air inlet notch 9 and the upper edge of the conical atomizing chamber 5 is 1 mm-2 mm, and the distance between the lower end of the air inlet notch 9 and the lower edge of the conical atomizing chamber 5 is 4 mm-5 mm.
The invention relates to a combustion method of a miniature liquid burner for reducing wet wall effect, which comprises the following steps:
the direct current power supplies of the fuel nozzle 7 and the metal grid 10 are connected, the fuel nozzle 7 is connected with the positive electrode of the power supply, and the metal grid 10 is grounded;
the liquid hydrocarbon fuel is sprayed out from a fuel nozzle 7 at the flow rate of 3-10 ml/h, is charged in a conical atomizing chamber 5 in a contact manner, is broken into fine mist droplets under the action of coulomb force and surface tension, and is captured by a metal grid 10 under the traction action of electric field force;
air passes through the air inlet pipeline 4 and flows through the air inlet notch 9, moves along the inner wall surface of the conical atomizing chamber 5 in a rotational flow mode, and forms a layer of air film on the inner wall surface of the conical atomizing chamber so as to prevent the phenomenon of wetting wall in the atomizing process; the venturi structure formed by combining the combustion chamber 13 and the conical atomizing chamber 5 ensures that the gas flow speed of the upper end area of the conical atomizing chamber 5 is higher than that of the lower end area, the pressure of the upper end area is lower than that of the lower end area, and liquid drops splashed on the inner wall surface of the conical atomizing chamber 5 in the atomizing process are lifted to the metal grid 10 by the air film which is rotationally lifted on the inner wall surface of the conical atomizing chamber 5 under the combined action of the pressure difference and the electric field force, so that the full utilization is realized; the mixed gas is ignited by the igniter 12 after passing through the porous medium disc 11, and is fully combusted in the combustion chamber 13, and the mixed gas rapidly expands when entering the combustion chamber 13 due to a venturi structure formed by the conical atomizing chamber 5 and the combustion chamber 13, so that the mixed gas forms reflux in the combustion chamber 13 under the choked flow action of the step 17 in the middle part of the combustion chamber 13, and the residence time of the fuel in the combustion chamber 13 is prolonged; the burnt tail gas is discharged from the gap 15 at the upper end of the inner sleeve 3, the tail gas discharge channel and the tail gas discharge outlet 8 at the lower end of the outer sleeve 2 in sequence.
Compared with the prior art, the invention has the following advantages and effects:
1. the invention is provided with a plurality of symmetrically distributed air inlet cuts 9 along the circumferential wall surface of the conical atomizing chamber 5 in a tangential direction; a plurality of air inlet pipes 4 penetrate through the outer sleeve 2 and the inner sleeve 3 and are communicated with the air cavity 16; the external air is introduced into the air cavity 16 through the air inlet pipeline 4, then moves along the inner wall surface of the conical atomizing chamber 5 in a rotational flow mode through the air inlet notch 9, and forms a layer of air film on the inner wall surface of the conical atomizing chamber 5. By adopting the tangential rotational flow air inlet mode, four air inlet notches are formed on the wall surface of the conical atomizing chamber, so that an air film can be effectively formed on the wall surface of the conical atomizing chamber under the condition that the ventilation speed is not very high, and serious wall wetting phenomenon in the spraying process is reduced. Meanwhile, the top structure of the conical atomizing chamber adopts a truncated cone shape, and because the air flow speed of the upper end area of the truncated cone is faster than that of the lower end area of the truncated cone, the pressure above the conical atomizing chamber is small, and liquid drops splashed to the wall surface can be brought up by the air film to form a metal grid under the action of pressure difference and electric field force, so that the full utilization of fuel is facilitated.
2. The inner cavity of the combustion chamber 13 is divided into an upper cavity and a lower cavity, the diameter of the upper cavity is smaller than that of the lower cavity, and the joint transition part of the upper cavity and the lower cavity is a right-angle transition; the right angle transition forms an inner step 17; while the combustion chamber 13 and the conical atomizing chamber 5 combine to form a venturi structure. The cross section of the combustion chamber is suddenly expanded when the combustion chamber is connected with the conical atomization chamber, so that the mixed gas can generate a backflow phenomenon in the combustion chamber, the residence time of fuel is prolonged, and the combustion temperature distribution is more uniform.
3. The exhaust gas after combustion in the combustion chamber 13 of the present invention is not directly discharged, but flows from top to bottom through the detouring to the exhaust gas passage, and is discharged through the exhaust gas outlet at the lower part. In the tail gas channel, high temperature tail gas and fresh air continuously exchange heat, not only can preheat the air, but also can keep the temperature of the burner, so that an effective heat preservation layer is formed, heat loss is reduced, and combustion efficiency is greatly improved.
4. The invention adopts a tangential air inlet mode along the inner wall surface of the conical atomizing chamber, does not interfere the jet flow area in the center of the conical atomizing chamber, and ensures that the atomizing structure is more stable due to the cyclone effect.
5. The combustion chamber 13 adopts the porous medium disc, so that the evaporation surface area of the liquid hydrocarbon fuel is increased, and the dispersion and the endothermic evaporation of the liquid fuel are facilitated; in addition, the porous medium disc has the functions of heat accumulation and heat conduction, and can preheat liquid near the metal grid, so that the combustion stability is greatly improved.
6. The invention has compact structure, small processing difficulty, excellent performance, convenient assembly and wide application prospect.
Drawings
FIG. 1 is a schematic view of a micro liquid burner with reduced wet wall effect according to the present invention.
FIG. 2 is a schematic view of the cross-sectional structure A-A in FIG. 1.
FIG. 3 is a schematic view of the cross-sectional structure B-B in FIG. 1.
FIG. 4 is a schematic view of the cross-sectional structure of C-C in FIG. 1.
Fig. 5 is a schematic diagram of a combination of a metal mesh and a porous media disc.
Detailed Description
The present invention will be described in further detail with reference to specific examples.
Examples
As shown in fig. 1-5. The invention discloses a miniature liquid burner for reducing wet wall effect, which comprises an outer sleeve 2, an inner sleeve 3 and a combustion chamber 13 arranged at the upper part in the inner sleeve 3; the outer sleeve 2 and the inner sleeve 3 are sleeved with each other, the lower ends of the outer sleeve 2 and the inner sleeve 3 are fixed on the lower cover plate 6 in a sealing way, and the upper end of the outer sleeve 2 is sealed by the upper cover plate 1; the lower cover plate 6 is provided with a fuel nozzle 7; the outer sleeve 2 and the inner sleeve 3 are mutually spaced and form an exhaust gas discharge channel; a gap 15 is reserved between the upper end of the inner sleeve 3 and the upper cover plate 1, and the upper port of the inner sleeve 3 is sealed with the outer edge of the combustion chamber 13; the tail gas after combustion in the combustion chamber 13 is sequentially discharged from a gap 15 at the upper end of the inner sleeve 3, a tail gas discharge channel and a tail gas discharge port 8 arranged at the lower end of the outer sleeve 2;
a conical atomizing chamber 5 with a small upper part and a large lower part which are butted with the bottom of the combustion chamber 13 is arranged in the inner sleeve 3 and on the lower cover plate 6; a metal grid 10 and a porous medium disc 11 are sequentially arranged at the top of the conical atomizing chamber 5;
the outer wall of the conical atomizing chamber 5 and the space between the outer wall of the combustion chamber 13 and the inner wall of the inner sleeve 3 form an air chamber 16;
a plurality of symmetrically distributed air inlet cuts 9 are tangentially arranged along the peripheral wall surface of the conical atomizing chamber 5; a plurality of air inlet pipes 4 penetrate through the outer sleeve 2 and the inner sleeve 3 and are communicated with the air cavity 16; the external air is introduced into the air cavity 16 through the air inlet pipeline 4, then moves along the inner wall surface of the conical atomizing chamber 5 in a rotational flow mode through the air inlet notch 9, and forms a layer of air film on the inner wall surface of the conical atomizing chamber 5.
The inner cavity of the combustion chamber 13 is divided into an upper cavity and a lower cavity, the diameter of the upper cavity is smaller than that of the lower cavity, and the joint transition part of the upper cavity and the lower cavity is a right-angle transition; the right angle transition forms an inner step 17.
The internal diameter of the combustion chamber 13 is greater than the internal diameter of the top of the conical atomizing chamber 5; the combustion chamber 13 and the conical atomizing chamber 5 are combined to form a venturi structure; the wall surface of the conical atomizing chamber 5 and the lower cover plate 6 form an acute angle of 78-82 degrees.
The outlet positions of the air inlet pipelines 4 respectively correspond to the inlets of the air inlet notches 9;
the air inlet notch 9 is a strip-shaped vertical notch, and the outlet position of each air inlet pipeline 4 is positioned in the middle of the strip-shaped vertical notch.
The fuel nozzle 7 penetrates the lower cover plate 6 and extends into the conical atomizing chamber 5, and is positioned in the middle of the conical atomizing chamber 5.
An igniter 12 is provided above the side of the porous medium disc 11, and the igniter 12 is connected to an external power source through a wire 14.
The distance between the upper end of the air inlet notch 9 and the upper edge of the conical atomizing chamber 5 is 1 mm-2 mm, and the distance between the lower end of the air inlet notch 9 and the lower edge of the conical atomizing chamber 5 is 4 mm-5 mm.
The top of the conical atomizing chamber 5 is a round platform plane.
The upper cover plate 1 is round, adopts ceramic materials with low heat conductivity coefficient and high temperature resistance, has the diameter of 30mm and the thickness of 3mm. The wire 14 (igniter lead) is threaded through a 1mm aperture.
The outer sleeve 2 is made of a material with low heat conductivity coefficient and high temperature resistance, ceramic is selected, the height is 58mm, and the thickness is 2mm. The exhaust outlet 8 has a diameter of about 2-3 mm, is spaced from the lower cover plate 6 by a distance of 3-4 mm, and is symmetrical about the central axis of the burner.
The lower cover plate 6 is round, adopts low heat conductivity and insulating material, and adopts silicon carbide, the diameter is 30mm, and the thickness is 3mm. The center of the circumference of the nozzle is provided with a small hole of 1mm, and the fuel nozzle 7 passes through the small hole and stretches into the conical atomizing chamber 5 for 3-4 mm.
The inner diameter of the fuel nozzle 7 is 0.5-0.8 mm, the outer diameter is 0.8-1.2 mm, stainless steel is adopted as the material, and the material is in interference fit with the small holes, and the total length is 12mm; the fuel is liquid hydrocarbon fuel.
The fuel nozzle 7 is externally connected with the positive electrode of a direct current power supply, the voltage is 2-10 kv, the metal grid is grounded, and spray is formed in the conical atomizing chamber 5.
The inner sleeve 3 is made of high-heat-conductivity and high-temperature-resistant materials, stainless steel is selected, and the height is 56mm; is separated from the outer sleeve 2 and the upper cover plate 1 by 2-3 mm and is connected with the lower cover plate 6 to form a tail gas channel.
The conical atomizing chamber 5 is made of high-heat-conductivity and high-temperature-resistant materials, ceramic is adopted, the diameter of the lower end of the conical atomizing chamber is larger than that of the upper end of the conical atomizing chamber, and an acute angle formed by the wall surface and the lower cover plate 6 is 78-82 degrees.
The conical atomizing chamber 5 has smooth inner wall surface, reduced adsorption to splashed liquid drop, inner diameter of the upper end of the chamber being 10mm, outer diameter of the chamber being 12mm, inner diameter of the lower end being 16mm, outer diameter being 18mm, and wall thickness being 2mm.
The lower end of the round table of the conical atomizing chamber 5 is connected with the lower cover plate 6 and the inner sleeve 3, the upper end of the conical atomizing chamber is connected with the combustion chamber 13, interference fit is adopted, and the upper end of the conical atomizing chamber extends into the combustion chamber 13 for 0.5mm.
The conical atomizing chamber 5 has a height of 26mm, and the air inlet slit 9 in the circumferential direction of the outer wall surface thereof has a width of 0.5 to 1.5mm and a height of 20mm.
The air inlet notch 9 is four on the outer wall surface of the conical atomizing chamber 5 and is uniformly distributed along the circumference;
the diameter of the metal grid 10 is 0.7-0.9 times of the outer diameter of the upper end of the circular table, stainless steel is selected as the material, the thickness is 0.3-0.5 mm, the grid density is 100 holes/cm < 2 >, and the effect is to collect liquid drops.
The porous medium disc 11 is arranged on the metal grid 10 and connected with the metal grid 10, the diameter of the porous medium disc is 0.5-0.8 times of the diameter of the metal grid 10, the porous medium disc is made of a sintering material with certain air permeability and excellent performance, the silicon carbide sintering material is selected, the air permeability is 37%, the thickness of the porous medium disc is 3-7 mm, the porous medium disc can enable the combustion temperature to be distributed more uniformly, and the porous medium disc has the functions of heat accumulation and heat conduction and can preheat mixed gas near the metal grid.
The combustion chamber 13 is made of a material with low heat conductivity and high temperature resistance, and ceramic is used for reducing heat loss in the combustion process; the combustion chamber 13 is a hollow cylinder with steps, and the function of the combustion chamber is to enable mixed gas to flow back, the inner diameter of one end matched with the conical atomizing chamber 5 is 12mm, the outer diameter is 14mm, the height from the inner step is 20mm, and the wall thickness is 2mm.
The inner step of the combustion chamber 13 is contracted inwards by 1-2 mm, the height above the inner step is 10mm, the wall thickness is 2mm, and the top end is connected with the inner sleeve 3.
The inner sleeve 3, the conical atomizing chamber 5, the combustion chamber 13 and the lower cover plate 6 form an air cavity, and the tail gas after combustion continuously exchanges heat with the air in the air cavity through a tail gas discharge channel formed by the outer sleeve 2 and the inner sleeve 3, so that the purposes of preheating the air by using the waste heat of the tail gas, preserving the heat of the burner and reducing heat loss are achieved.
The center line of the air inlet channel 4 has the same angle with the air inlet notch 9, and the air inlet is ensured to be smooth, so that the air can smoothly enter along the inner wall surface of the conical atomizing chamber 5; the air inlet passages 4 are distributed uniformly in the circumferential direction on the outer sleeve 2 in a total of four, each corresponding to one air inlet cut 9.
The combustion method of the miniature liquid burner for reducing the wet wall effect can be realized by the following steps:
the direct current power supplies of the fuel nozzle 7 and the metal grid 10 are connected, the fuel nozzle 7 is connected with the power supply anode, the metal grid 10 is grounded, and the voltage value of the direct current power supply can be correspondingly adjusted along with the atomization effect.
The liquid hydrocarbon fuel is sprayed out from a fuel nozzle 7 at the flow rate of 3-10 ml/h, is charged in a conical atomizing chamber 5 in a contact manner, is broken into fine mist droplets under the action of coulomb force and surface tension, and is captured by a metal grid 10 under the traction action of electric field force;
air passes through the air inlet pipeline 4 and flows through the air inlet notch 9, moves along the inner wall surface of the conical atomizing chamber 5 in a rotational flow mode, and forms a layer of air film on the inner wall surface of the conical atomizing chamber so as to prevent the phenomenon of wetting wall in the atomizing process; the venturi structure formed by combining the combustion chamber 13 and the conical atomizing chamber 5 ensures that the gas flow speed of the upper end area of the conical atomizing chamber 5 is higher than that of the lower end area, the pressure of the upper end area is lower than that of the lower end area, and liquid drops splashed on the inner wall surface of the conical atomizing chamber 5 in the atomizing process are lifted to the metal grid 10 by the air film which is rotationally lifted on the inner wall surface of the conical atomizing chamber 5 under the combined action of the pressure difference and the electric field force, so that the full utilization is realized; the mixed gas is ignited by the igniter 12 after passing through the porous medium disc 11, and is fully combusted in the combustion chamber 13, and the mixed gas rapidly expands when entering the combustion chamber 13 due to a venturi structure formed by the conical atomizing chamber 5 and the combustion chamber 13, so that the mixed gas forms reflux in the combustion chamber 13 under the choked flow action of the step 17 in the middle part of the combustion chamber 13, and the residence time of the fuel in the combustion chamber 13 is prolonged; the burnt tail gas is discharged from the gap 15 at the upper end of the inner sleeve 3, the tail gas discharge channel and the tail gas discharge outlet 8 at the lower end of the outer sleeve 2 in sequence.
As described above, the present invention can be preferably realized.
The embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principles of the invention should be made and equivalents should be construed as falling within the scope of the invention.
Claims (6)
1. A miniature liquid burner for reducing wet wall effect comprises an outer sleeve (2), an inner sleeve (3) and a combustion chamber (13) arranged at the inner upper part of the inner sleeve (3); the outer sleeve (2) and the inner sleeve (3) are sleeved with each other, the lower ends of the outer sleeve and the inner sleeve are fixed on the lower cover plate (6) in a sealing way, and the upper end of the outer sleeve (2) is sealed by the upper cover plate (1); a fuel nozzle (7) is arranged on the lower cover plate (6); the method is characterized in that:
the outer sleeve (2) and the inner sleeve (3) are mutually spaced and form an exhaust gas discharge channel; a gap (15) is reserved between the upper end of the inner sleeve (3) and the upper cover plate (1), and the upper port of the inner sleeve (3) is sealed with the outer edge of the combustion chamber (13); the tail gas after combustion in the combustion chamber (13) is sequentially discharged from a gap (15) at the upper end of the inner sleeve (3), a tail gas discharge channel and a tail gas discharge port (8) arranged at the lower end of the outer sleeve (2);
a conical atomizing chamber (5) with a small upper part and a big lower part which are butted with the bottom of the combustion chamber (13) is arranged in the inner sleeve (3) and on the lower cover plate (6); a metal grid (10) and a porous medium disc (11) are sequentially arranged at the top of the conical atomizing chamber (5);
the outer wall of the conical atomizing chamber (5) and the space between the outer wall of the combustion chamber (13) and the inner wall of the inner sleeve (3) form an air cavity (16);
a plurality of symmetrically distributed air inlet cuts (9) are tangentially arranged along the peripheral wall surface of the conical atomizing chamber (5); a plurality of air inlet pipelines (4) penetrate through the outer sleeve (2) and the inner sleeve (3) and are communicated with the air cavity (16); the external air is introduced into the air cavity (16) through the air inlet pipeline (4), then moves along the inner wall surface of the conical atomizing chamber (5) in a rotational flow mode through the air inlet notch (9), and forms a layer of air film on the inner wall surface of the conical atomizing chamber (5);
the outlet positions of the air inlet pipelines (4) respectively correspond to the inlets of the air inlet notches (9);
the air inlet notch (9) is a strip-shaped vertical notch, and the outlet position of each air inlet pipeline (4) is positioned in the middle of the strip-shaped vertical notch;
the fuel nozzle (7) penetrates through the lower cover plate (6) and stretches into the conical atomizing chamber (5) and is positioned in the middle of the conical atomizing chamber (5).
2. The micro liquid burner for reducing the wet wall effect according to claim 1, wherein: the inner cavity of the combustion chamber (13) is divided into an upper cavity and a lower cavity, the diameter of the upper cavity is smaller than that of the lower cavity, and the joint transition part of the upper cavity and the lower cavity is a right-angle transition; the right angle transition forms an inner step (17).
3. The micro liquid burner for reducing the wet wall effect according to claim 2, wherein: the inner diameter of the lower cavity of the combustion chamber (13) is larger than that of the top of the conical atomizing chamber (5); the combustion chamber (13) and the conical atomizing chamber (5) are combined to form a Venturi structure; the acute angle formed by the wall surface of the conical atomizing chamber (5) and the lower cover plate (6) is 78-82 degrees.
4. A micro liquid burner for reducing the wet wall effect according to claim 3, wherein: an igniter (12) is arranged above the side of the porous medium disc (11), and the igniter (12) is connected with an external power supply through a lead (14).
5. A micro liquid burner for reducing the wet wall effect according to claim 3, wherein:
the distance between the upper end of the air inlet notch (9) and the upper edge of the conical atomizing chamber (5) is 1-2 mm, and the distance between the lower end of the air inlet notch (9) and the lower edge of the conical atomizing chamber (5) is 4-5 mm.
6. A method of burning a micro-scale liquid burner having reduced wet wall effect according to any one of claims 1-5, comprising the steps of:
the direct current power supply of the fuel nozzle (7) and the metal grid (10) is connected, the fuel nozzle (7) is connected with the positive electrode of the power supply, and the metal grid (10) is grounded;
the liquid hydrocarbon fuel is sprayed out from a fuel nozzle (7) at the flow rate of 3-10 ml/h, is charged in a conical atomizing chamber (5) in a contact manner, is broken into fine mist droplets under the action of coulomb force and surface tension, and is captured by a metal grid (10) under the traction action of electric field force;
the air passes through the air inlet pipeline (4) and flows through the air inlet notch (9), moves along the inner wall surface of the conical atomizing chamber (5) in a rotational flow mode, and forms a layer of air film on the inner wall surface of the conical atomizing chamber so as to prevent the phenomenon of wetting walls in the atomizing process; the venturi structure formed by combining the combustion chamber (13) and the conical atomizing chamber (5) ensures that the gas flow speed of the upper end area of the conical atomizing chamber (5) is higher than that of the lower end area, the pressure of the upper end area is lower than that of the lower end area, and liquid drops splashed onto the inner wall surface of the conical atomizing chamber (5) in the atomizing process are lifted to the metal grid (10) by the air film which is rotationally lifted on the inner wall surface of the conical atomizing chamber (5) under the combined action of the pressure difference and the electric field force, so that the full utilization is realized; the mixed gas is ignited by an igniter (12) after passing through a porous medium disc (11), and is fully combusted in a combustion chamber (13), and the mixed gas is rapidly expanded when entering the combustion chamber (13) due to a Venturi structure formed by a conical atomizing chamber (5) and the combustion chamber (13), so that the mixed gas forms backflow in the combustion chamber (13) under the choked flow action of a step (17) in the middle part of the combustion chamber (13), and the residence time of fuel in the combustion chamber (13) is prolonged; the tail gas after combustion is discharged from a gap (15) at the upper end of the inner sleeve (3), a tail gas discharge channel and a tail gas discharge outlet (8) arranged at the lower end of the outer sleeve (2) in sequence.
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