Micro-charged spray burner using porous medium electrode and combustion method thereof

Abstract

A micro-charged spray burner using a porous medium electrode includes an upper cover plate, a lower cover plate, an outer sleeve, a heat exchange sleeve, a diverter sleeve, a combustion sleeve, an inner sleeve, a porous medium electrode, an air inlet pipe, a primary air duct, a secondary air duct, a fuel liquid delivery pipe, a DC power supply, and an igniter. Liquid fuel flows in from the fuel tank inside the inner sleeve, flows out from the nozzle, and then is broken in the atomization zone and mixed evenly with the secondary air, and finally enters the combustion zone for combustion, wherein the secondary air flow channel and the nozzle are arranged in a circumferential direction. It also relates to a combustion method of the above-mentioned burner. The present invention adopts a porous medium electrode, greatly reduces the electrode distance, the multi-layer circumferential distribution of the nozzle, and the combustion mode of the secondary air supply, which on the one hand improves the atomization effect of the liquid fuel and further improves the combustion efficiency and energy density of the burner, and on the other hand reduces the volume of the atomization zone, further reduces the size of the micro-charged spray burner, and belongs to the technical field of micro liquid fuel combustion devices.

Description

Technical Field

[0001] The invention relates to the technical field of micro liquid combustion devices, and in particular to a micro charged spray burner utilizing porous medium electrodes and a combustion method thereof. Background Art

[0002] In recent years, with the rapid development of micro-electromechanical systems (MEMS), equipment has gradually shifted towards miniaturization and multifunctionality, and a large number of micro-medical devices, micro-robots, micro-aircraft, portable electronic devices and other micro-devices have emerged. At present, the power source of these micro-devices is mostly supplied by traditional chemical batteries, but the shortcomings of chemical batteries such as low energy density, long charging time and short battery life limit the development and promotion of micro-devices. The energy density of liquid hydrocarbon fuels is much greater than that of traditional chemical batteries, and it is convenient for storage and transportation, efficient and clean combustion, and good combustion durability. It is expected to replace chemical batteries. Therefore, the combustion of liquid hydrocarbon fuels has gradually become the focus of people's attention.

[0003] The key to achieving efficient and clean combustion of liquid fuels lies in the evaporation of liquid fuels and the organizational form of the combustion zone. The droplets produced after the liquid fuel is charged and atomized have the characteristics of good monodispersity, which greatly increases the contact area with the air, thereby accelerating the evaporation of the liquid fuel. The combustion method of the traditional micro burner is premixed combustion. In the second half of the combustion, there is an incomplete combustion phenomenon due to the consumption of oxygen. If a more complete combustion is to be achieved, the method of increasing the amount of air is adopted, which reduces the flame temperature and increases the amount of flue gas, increases the exhaust loss, and reduces the combustion efficiency. At present, the atomization zone of the liquid fuel charged spray burner is below the combustion zone, and the combustion zone and the atomization zone are relatively separated. The high-temperature flame is not fully utilized to accelerate the evaporation of the droplets in the atomization zone. At the same time, the electrode distance in the atomization zone is large, resulting in a larger size of the burner.

[0004] The porous medium electrode is used to greatly reduce the electrode distance, the nozzle is multi-layered annularly distributed, and the secondary air supply combustion method is used to improve the combustion efficiency and energy density of the burner, while further reducing the size of the burner. Summary of the invention

[0005] In view of the technical problems existing in the prior art, the purpose of the present invention is to provide a micro-charged spray burner using porous medium electrodes and a combustion method thereof which can fully preheat air and liquid fuel.

[0006] In order to achieve the above-mentioned object, the present invention adopts the following technical scheme: a micro-charged spray burner using a porous medium electrode, comprising an upper cover plate, a lower cover plate, an outer sleeve, a heat exchange sleeve, a flow divider sleeve, a combustion sleeve, an inner sleeve, a porous medium electrode, an air inlet pipe, a primary air pipe, a secondary air pipe, a fuel liquid delivery pipe, a DC power supply and an igniter;

[0007] The porous medium electrode is cylindrical, the top of the outer sleeve is sealed by the upper cover plate, the bottom of the outer sleeve is sealed by the lower cover plate, the heat exchange sleeve is located inside the outer sleeve, the outside of the heat exchange sleeve forms a flue gas channel, the combustion sleeve, the porous medium electrode and the inner sleeve are all located inside the heat exchange sleeve, an annular cavity is formed between the combustion sleeve and the heat exchange sleeve, the air inlet pipe passes through the outer sleeve and the heat exchange sleeve and extends into the cavity, the porous medium electrode is located below the combustion sleeve, the inside of the porous medium electrode and the inside of the combustion sleeve A combustion zone is formed, the inner sleeve is located outside the porous medium electrode, an annular atomization zone is formed between the inner sleeve and the porous medium electrode, the split sleeve is located between the inner sleeve and the heat exchange sleeve, a first interval is formed between the split sleeve and the inner sleeve, a second interval is formed between the split sleeve and the heat exchange sleeve, a primary air duct passes through the inner sleeve and the porous medium electrode, the cavity is connected to the combustion zone through the first interval and the primary air duct, the secondary air duct passes through the inner sleeve and the split sleeve, the cavity is connected to the atomization zone through the second interval and the secondary air duct;

[0008] An annular fuel groove is opened inside the inner sleeve, and the fuel delivery pipe passes through the outer sleeve, the heat exchange sleeve and the inner sleeve and extends into the fuel groove. The inner wall of the inner sleeve is provided with a nozzle connected to the groove. The positive pole of the DC power supply is connected to the inner surface of the fuel groove, the negative pole of the DC power supply is connected to the porous medium electrode, and the igniter is located in the combustion zone.

[0009] After adopting this structure, the air intake channel of the burner is mainly composed of a cavity, a second interval, and a first interval. The air intake pipe is connected to the cavity, and the cavity is connected to the second interval and the first interval respectively. The second interval is a secondary air channel, and the outer side exchanges heat with the flue gas channel through a heat exchange sleeve. The first interval is a primary air duct, and the inner side exchanges heat with the liquid fuel through an inner sleeve. The air entering the cavity fully exchanges heat with the flue gas in a countercurrent heat exchange manner, and then flows into the secondary air duct and the primary air duct respectively. The air in the secondary air duct further exchanges heat with the high-temperature flue gas to increase the temperature, while the air in the primary air duct heats the liquid fuel, thereby improving atomization and accelerating evaporation.

[0010] As a preference, the micro-charged spray burner using porous medium electrodes also includes a fuel tank and a fuel supply pump. The fuel tank is installed on the top of the upper cover plate, the fuel tank is connected to the fuel delivery pipe, and the fuel supply pump is installed on the fuel delivery pipe.

[0011] As a preferred embodiment, the heat exchange sleeve includes a cylindrical heat exchange sleeve body and an annular top cover located at the top of the heat exchange sleeve body, and the combustion sleeve includes a cylindrical combustion sleeve body and an annular bottom plate located at the bottom end of the combustion sleeve body, so that the cross-section of the heat exchange sleeve is an inverted L-shape, the cross-section of the combustion sleeve is L-shaped, the top of the combustion sleeve is connected to the inner edge of the annular top cover, and the top of the porous medium electrode and the top of the inner sleeve are both attached to the annular bottom plate.

[0012] As a preferred embodiment, the outer sleeve is provided with an exhaust port, the combustion zone is connected to the exhaust port through a smoke channel, the heights of the air inlet pipe, the fuel liquid delivery pipe and the exhaust port on the outer sleeve decrease successively, the number of the exhaust port and the air inlet pipe are four respectively, the four air inlet pipes are evenly distributed in a ring shape, and the four air inlet pipes are aligned with the four exhaust ports respectively.

[0013] As a preference, the diverter sleeve has the same height as the inner sleeve, and comprises an upper section and a lower section, wherein the outer diameter of the lower section is larger than the outer diameter of the upper section, thereby forming a step between the lower section and the upper section, and the outer wall of the lower section is fitted and fixed to the inner wall of the heat exchange sleeve.

[0014] As a preference, the primary air duct is attached to the upper surface of the lower cover plate, the end of the primary air duct is arc-shaped, and the inner surface of the end of the primary air duct is tangent to the inner surface of the porous medium electrode.

[0015] As a preferred embodiment, the secondary air duct is a straight tube structure and is perpendicular to the axis of the porous medium electrode, and the secondary air duct passes through the upper section and the inner sleeve of the split sleeve.

[0016] As a preferred embodiment, the secondary air ducts and nozzles are distributed in several layers along the vertical direction, each layer of secondary air ducts includes 6 secondary air ducts distributed in a ring, and each layer of nozzles includes 6 nozzles distributed in a ring. On the horizontal projection plane, the secondary air ducts and nozzles are evenly staggered along the ring.

[0017] As a preference, the distance between the nozzle and the porous medium electrode is less than 5 cm.

[0018] The combustion method of a micro-charged spray burner using a porous medium electrode includes the following steps:

[0019] Turn on the DC power supply and the fuel supply pump. The liquid fuel in the fuel tank enters the fuel tank from the fuel delivery pipe under the push of the fuel supply pump, and then flows out of the nozzle. Under the action of the electric field force, the fuel droplets sprayed from the nozzle are broken into mist droplets and move to the porous medium electrode. Among them, most of the mist droplets pass through the porous medium electrode and enter the combustion zone, and a small part of the mist droplets hit the porous medium electrode;

[0020] The air enters the cavity from the air inlet pipe, and then passes through the flow distribution of the splitter sleeve, and the air is divided into primary air and secondary air. The primary air swirls into the combustion zone from the first interval and the primary air duct, and the secondary air enters the atomization zone from the second interval and the secondary air duct, and then is premixed with the fuel in the atomization zone, and the droplets and evaporated fuel are blown out of the atomization zone and the porous medium electrode and enter the combustion zone;

[0021] Under the action of the igniter, the fuel starts to burn and generates flames. The flames heat the porous medium electrode and the combustion sleeve by radiation and convection, so that the droplets in the porous medium electrode and the droplets in the atomization area evaporate quickly. At the same time, the porous medium electrode heats the inner sleeve by radiation heat transfer to preheat the fuel, and sufficient heat exchange is carried out between the combustion sleeve and the gas in the cavity.

[0022] The flue gas generated by combustion first preheats the liquid fuel in the fuel tank, then fully exchanges heat with the air through the heat exchange sleeve, and then is discharged from the exhaust port, completing the entire combustion process.

[0023] In general, the present invention has the following advantages:

[0024] 1. The primary air of this burner enters the combustion zone in the form of swirl air supply, which increases the residence time of the fuel and accelerates the mixing with the fuel, thereby obtaining a uniformly distributed temperature field; the secondary air enters the combustion zone in the form of lateral wind, firstly, to blow the spray out of the atomization zone into the combustion zone, secondly, to supplement the unburned fuel in a partially premixed combustion mode, and thirdly, to provide lateral disturbances to further increase the residence time of the fuel in the combustion zone, thereby improving the combustion efficiency of the fuel.

[0025] 2. The electrode distance of this burner is extremely small (no more than 5 mm), and the porous medium is used as the ground electrode. This design can greatly reduce the volume of the atomization zone and the size of the combustion zone, and can further reduce the size of the burner and make the structure compact. Such an electrode structure allows a small part of the spray droplets to hit the porous medium, and most of the spray droplets pass through the porous medium into the combustion zone. The spray droplets enter the combustion zone and burn, so that the fuel concentration is redistributed again, increasing the fuel concentration around the spray droplets, thereby obtaining a higher temperature. In addition, the reduction in the electrode distance can reduce the required voltage. The arrangement of the porous medium electrode in close contact with the combustion zone can make full use of the high-temperature flame of the fuel combustion, heat the porous medium by radiation heat transfer, and then heat the atomization zone, as well as preheat the liquid fuel in the inner sleeve, increase the evaporation rate of the spray droplets, increase the heat released by the fuel per unit time, and thus improve the energy density of the burner.

[0026] 3. The nozzle components of this burner are arranged in three layers in parallel. There are six nozzles in each layer, which are evenly distributed along the circumference and have the same height, which can make full use of the space in the atomization chamber and help the extension of the spray. In the horizontal projection, the secondary air duct and the nozzle are staggered, and in the vertical projection, the secondary air duct and the nozzle are staggered. The secondary air duct is arranged in two layers in parallel, and each layer has six secondary air ducts evenly distributed along the circumference, so that the secondary air duct and the nozzle are arranged in a cross-row, which is conducive to the full mixing of the spray and the secondary air, providing a basis for stable combustion.

[0027] 4. The fuel tank of this burner is designed in the center of the upper cover plate, and the heat of the upper cover plate can be used to preheat the liquid fuel. At the same time, the fuel tank is designed at a high place to make full use of its gravitational potential energy to reduce the power of the fuel supply pump. Under the action of the fuel supply pump, the preheated liquid fuel enters the fuel tank in the inner sleeve through the fuel delivery pipe, and is preheated twice in the inner sleeve. The increase in the temperature of the liquid fuel improves the spray and accelerates the evaporation rate of the fuel. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the structure of a micro charged spray burner using porous medium electrodes.

[0029] Figure 2 for Figure 1 Schematic diagram of the structure of the AA section.

[0030] Figure 3 for Figure 1 Schematic diagram of the structure of the BB section.

[0031] Figure 4 for Figure 1 Schematic diagram of the structure of the CC section.

[0032] Figure 5 for Figure 2 Schematic diagram of the structure of the DD section.

[0033] Figure 6 for Figure 2 Schematic diagram of the structure of the EE section.

[0034] Figure 7 This is a schematic diagram of the structure of the primary air duct.

[0035] Among them, 1 is an upper cover plate, 2 is a lower cover plate, 3 is an outer sleeve, 4 is a heat exchange sleeve, 5 is a diverter sleeve, 6 is a combustion sleeve, 7 is an inner sleeve, 8 is a porous medium electrode, 9 is a primary air duct, 10 is an air inlet pipe, 11 is a fuel liquid delivery pipe, 12 is an exhaust port, 13 is a fuel tank, 14 is a nozzle, 15 is a secondary air duct, 16 is a first interval, 17 is a cavity, 18 is a second interval, 19 is a flue gas channel, 20 is an atomization area, 21 is a combustion area, 22 is a fuel tank, 23 is a positive wire hole, 24 is a negative wire hole, 25 is an igniter lead hole, 26 is an igniter, 27 is a high-voltage DC power supply, 28 is a lead, 29 is a positive wire, 30 is a small hole, 31 is a negative wire, and 32 is a fuel supply pump. DETAILED DESCRIPTION

[0036] The present invention will be further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0037] Embodiment 1

[0038] like Figure 1 to Figure 7 As shown, a micro charged spray burner using a porous medium electrode includes an upper cover plate, a lower cover plate, an outer sleeve, a heat exchange sleeve, a flow divider sleeve, a combustion sleeve, an inner sleeve, a porous medium electrode, an air inlet pipe, a primary air pipe, a secondary air pipe, a fuel liquid delivery pipe, a DC power supply and an igniter;

[0039] The porous medium electrode is cylindrical, the top of the outer sleeve is sealed by the upper cover plate, the bottom of the outer sleeve is sealed by the lower cover plate, the heat exchange sleeve is located inside the outer sleeve, the outside of the heat exchange sleeve forms a flue gas channel, the combustion sleeve, the porous medium electrode and the inner sleeve are all located inside the heat exchange sleeve, an annular cavity is formed between the combustion sleeve and the heat exchange sleeve, the air inlet pipe passes through the outer sleeve and the heat exchange sleeve and extends into the cavity, the porous medium electrode is located below the combustion sleeve, the inside of the porous medium electrode and the inside of the combustion sleeve A combustion zone is formed, the inner sleeve is located outside the porous medium electrode, an annular atomization zone is formed between the inner sleeve and the porous medium electrode, the split sleeve is located between the inner sleeve and the heat exchange sleeve, a first interval is formed between the split sleeve and the inner sleeve, a second interval is formed between the split sleeve and the heat exchange sleeve, a primary air duct passes through the inner sleeve and the porous medium electrode, the cavity is connected to the combustion zone through the first interval and the primary air duct, the secondary air duct passes through the inner sleeve and the split sleeve, the cavity is connected to the atomization zone through the second interval and the secondary air duct;

[0040] An annular fuel groove is opened inside the inner sleeve, and the fuel delivery pipe passes through the outer sleeve, the heat exchange sleeve and the inner sleeve and extends into the fuel groove. The inner wall of the inner sleeve is provided with a nozzle connected to the groove. The positive pole of the DC power supply is connected to the inner surface of the fuel groove, the negative pole of the DC power supply is connected to the porous medium electrode, and the igniter is located in the combustion zone.

[0041] The micro-charged spray burner using porous medium electrodes also includes a fuel tank and a fuel supply pump. The fuel tank is installed on the top of the upper cover plate, the fuel tank is connected to the fuel delivery pipe, and the fuel supply pump is installed on the fuel delivery pipe.

[0042] The DC power supply is a high voltage DC power supply. Three through holes are arranged on the bottom surface of the lower cover. The axes of the three through holes and the axes of the left and right nozzles are on the same plane. The through holes on the lower cover are the positive wire hole, the negative wire hole, and the igniter lead hole from left to right.

[0043] The igniter is close to the inner surface of the porous medium and the upper surface of the primary air duct outlet. The igniter is led out from the igniter lead hole of the lower cover plate through a lead wire and connected to an external power supply. The positive electrode of the high-voltage DC power supply is introduced into the first interval of the burner through the positive lead wire from the positive lead hole of the lower cover plate, and then enters the inner surface of the inner sleeve annular groove from the small hole on the outer wall of the inner sleeve, so that the lead is in direct contact with the liquid fuel. The negative electrode of the high-voltage DC power supply is introduced into the combustion zone of the burner from the negative lead hole of the lower cover plate, and then directly connected to the porous medium electrode.

[0044] After turning on the high-voltage DC power supply, an electrostatic field is formed between the nozzle and the porous medium electrode. Under the action of the electric field force, the fuel droplets ejected from the nozzle are broken into charged droplets, and the charged droplets are accelerated. However, when the electrode distance is extremely small, most of the droplets will pass through the porous medium electrode and enter the combustion zone, and a small part of the droplets will be captured by the porous medium electrode. The preheated secondary air flows from the cavity through the second interval and the secondary air duct in turn into the atomization zone, blowing the droplets into the combustion zone. At the same time, a lateral wind is also provided in the combustion zone to prolong the residence time of the fuel in the combustion zone and accelerate the evaporation of the droplets in the porous medium.

[0045] The inner sleeve is coated with medium-temperature resistant insulating material on all surfaces except the surface of the fuel tank.

[0046] The inner surface of the porous medium electrode is coated with Pt-Ni or Pt-Cu catalyst to improve combustion efficiency.

[0047] The fuel tank is located at the center of the top of the upper cover plate, and the porous electrode, combustion sleeve, and heat exchange sleeve are all coaxial with the outer sleeve. The high-temperature flue gas generated by combustion passes through the upper cover plate to preheat the liquid fuel in the fuel tank. Under the action of the fuel supply pump, the preheated fuel flows out from the lower left side of the fuel tank and enters the fuel tank in the inner sleeve under the guidance of the fuel delivery pipe. After secondary preheating and full charging in the fuel tank, it flows out from the nozzle and breaks into spray in the atomization area. The secondary air and spray are mixed and flow into the combustion area for combustion.

[0048] The heat exchange sleeve includes a cylindrical heat exchange sleeve body and an annular top cover located at the top end of the heat exchange sleeve body, and the combustion sleeve includes a cylindrical combustion sleeve body and an annular bottom plate located at the bottom end of the combustion sleeve body, so that the cross-section of the heat exchange sleeve is an inverted L-shape, the cross-section of the combustion sleeve is L-shaped, the top end of the combustion sleeve is connected to the inner edge of the annular top cover, and the top end of the porous medium electrode and the top end of the inner sleeve are both attached to the annular bottom plate.

[0049] The air flows into the cavity formed by the upper part of the heat exchange sleeve and the combustion sleeve through the air inlet pipe. The larger cavity allows the air and the flue gas to form a countercurrent heat exchange mode. At the same time, the air forms a reflux in the cavity, which increases the disturbance of the airflow and thus strengthens the heat exchange. The gas in the cavity also has a heat preservation effect, which keeps the combustion sleeve at a higher temperature, thus providing conditions for stable combustion.

[0050] The bottom end of the heat exchange sleeve fits tightly with the lower cover plate, the inner edge of the annular top cover of the heat exchange sleeve fits tightly with the top of the combustion sleeve, and the top of the porous electrode and the top of the inner sleeve fit tightly with the bottom end of the annular bottom plate respectively.

[0051] An exhaust port is opened in the outer sleeve, and the combustion zone is connected with the exhaust port through the smoke channel. The heights of the air inlet pipe, the fuel liquid delivery pipe and the exhaust port on the outer sleeve decrease successively. There are four exhaust ports and four air inlet pipes respectively. The four air inlet pipes are evenly distributed in a ring shape, and the four air inlet pipes are aligned with the four exhaust ports up and down respectively.

[0052] The splitter sleeve has the same height as the inner sleeve and includes an upper section and a lower section. The outer diameter of the lower section is greater than the outer diameter of the upper section, thereby forming a step between the lower section and the upper section. The outer wall of the lower section is fitted and fixed to the inner wall of the heat exchange sleeve.

[0053] The bottom end of the flow dividing sleeve is tightly fitted with the lower cover plate, a part of the bottom end of the inner sleeve is tightly fitted with the lower cover plate, and the other part is tightly fitted with the outer surface of the primary air duct.

[0054] The primary air duct is attached to the upper surface of the lower cover plate, the end of the primary air duct is arc-shaped, and the inner surface of the end of the primary air duct is tangent to the inner surface of the porous medium electrode.

[0055] The cross section of the primary air duct is an inverted U shape, with the opening facing the lower cover plate. A single primary air duct first passes through the inner sleeve vertically, and then its end passes through the atomization area and the porous medium electrode at a suitable arc, so that the arc on the inner side of the air duct is tangent to the porous medium electrode, thereby achieving the purpose of swirl air supply.

[0056] The secondary air duct is a straight tube structure and is perpendicular to the axis of the porous medium electrode. The secondary air duct passes through the upper section and the inner sleeve of the split sleeve.

[0057] The secondary air ducts and nozzles are distributed in several layers along the vertical direction, each layer of secondary air ducts includes 6 secondary air ducts distributed in a ring, and each layer of nozzles includes 6 nozzles distributed in a ring. On the horizontal projection plane, the secondary air ducts and nozzles are evenly staggered along the ring.

[0058] The nozzles are distributed in three layers along the vertical direction, and the secondary air duct is distributed in two layers along the vertical direction. The inner side of the secondary air duct exceeds the inner surface of the inner sleeve, and the outer side of the secondary air duct exceeds the outer surface of the diversion sleeve.

[0059] The distance between the nozzle and the porous medium electrode is less than 5 cm, which can not only reduce the voltage required for atomization at the same flow rate, but also reduce the size of the atomization zone, thereby further reducing the size of the burner.

[0060] Specifically, the upper cover has a diameter of 46 mm, a thickness of 2 mm, and is made of high-temperature resistant insulation material. The lower cover has a diameter of 50 mm and is made of high-temperature resistant insulation material. Two symmetrically distributed through holes are opened 4 mm from the center axis of the lower cover, which are the negative electrode wire hole and the igniter lead hole, and a positive electrode wire hole is opened 15 mm from the center axis. The diameter of the through holes is 0.5 mm.

[0061] The outer sleeve has an outer diameter of 46 mm, an inner diameter of 42 mm, and a height of 45 mm. The four intake pipes are evenly distributed along the circumference at a distance of 10 mm from the top of the outer sleeve, with an outer diameter of 3 mm, an inner diameter of 2 mm, and a length of 6 to 8 mm. The four exhaust ports are evenly distributed along the circumference at a distance of 3 mm from the bottom of the outer sleeve, and the exhaust port diameter is 3 mm.

[0062] The outer diameter of the lower end of the heat exchange sleeve is 38 mm, the inner diameter is 36 mm, the outer diameter of the upper end of the heat exchange sleeve is 38 mm, the inner diameter is 12 mm, and the height is 40 mm. The air intake pipe is 5 mm away from the top of the heat exchange sleeve, and the fuel delivery pipe is installed at a distance of 22.5 mm from the bottom of the heat exchange sleeve.

[0063] The split sleeve is stepped, with an outer diameter of 34 mm on the upper section and 36 mm on the lower section, a wall thickness of 1 mm, a height of 25 mm, and a step distance of 8 mm from the bottom of the split sleeve. The secondary air duct and the fuel liquid delivery pipe are interference fit with the split sleeve. The secondary air duct has an outer diameter of 3 mm, a wall thickness of 0.5 mm, and a length of 8 mm.

[0064] The outer diameter of the inner sleeve is 28 mm, the inner diameter is 20 mm, and the height is 25 mm. The fuel tank is opened 12 mm from the central axis of the inner sleeve, with a width of about 2 mm and a depth of 17 mm. There are three layers of parallel nozzles on the inner wall of the inner sleeve. The distance between two adjacent layers of nozzles is 5 mm. There are six nozzles on each layer. The inner diameter of the nozzles is 1 mm, the outer diameter is 1.2 mm, and the height is 3 mm. The material is stainless steel. The top layer of nozzles is 5 mm away from the top of the inner sleeve, and the bottom layer of nozzles is 10 mm away from the upper surface of the lower cover plate. The secondary air ducts are arranged in two layers in parallel, with six nozzles on each layer. The distance between each layer is 5 mm. The secondary air ducts and the nozzle group are arranged at a 30-degree offset. The upper secondary air duct is 2.5 mm away from the first layer of nozzles.

[0065] The mesh density of the porous medium electrode is 80 holes / cm2, and the inner surface thereof is coated with a Pt-Ni or Pt-Cu catalyst. The inner diameter of the porous medium electrode is 10 mm, the height is 25 mm, and the bottom end is tightly connected to the primary air duct.

[0066] The vertical cross-section of the combustion sleeve is L-shaped, with a height of 15 mm. The inner diameter of the vertical section is 10 mm, the outer diameter is 14 mm, and the wall thickness is 2 mm. The inner diameter of the horizontal section is 10 mm, the outer diameter is 45 mm, and the height is 1.5 mm. It forms a cavity with the heat exchange sleeve to improve air flow and preheat the air. It and the porous medium electrode together form a combustion zone, which prolongs the residence time of the mixed gas in the combustion zone, thereby increasing the combustion efficiency and improving the uniformity of the wall temperature distribution. The combustion sleeve is made of high-temperature resistant materials with low thermal conductivity.

[0067] Under the action of the fuel supply pump, the fuel flows from the fuel tank through the fuel delivery pipe into the fuel tank of the inner sleeve. Therefore, a through hole with a diameter of 3 mm is radially opened at a distance of 22.5 mm from the bottom end of the outer sleeve, heat exchange sleeve, diversion sleeve and inner sleeve respectively to allow the fuel delivery pipe to extend therein.

[0068] The combustion method of a micro-charged spray burner using a porous medium electrode includes the following steps:

[0069] Turn on the DC power supply and the fuel supply pump. The liquid fuel in the fuel tank enters the fuel tank from the fuel delivery pipe under the push of the fuel supply pump, and then flows out of the nozzle. Under the action of the electric field force, the fuel droplets sprayed from the nozzle are broken into mist droplets and move to the porous medium electrode. Among them, most of the mist droplets pass through the porous medium electrode and enter the combustion zone, and a small part of the mist droplets hit the porous medium electrode;

[0070] The air enters the cavity from the air inlet pipe, and then passes through the flow distribution of the splitter sleeve, and the air is divided into primary air and secondary air. The primary air swirls into the combustion zone from the first interval and the primary air duct, and the secondary air enters the atomization zone from the second interval and the secondary air duct, and then is premixed with the fuel in the atomization zone, and the droplets and evaporated fuel are blown out of the atomization zone and the porous medium electrode and enter the combustion zone;

[0071] Under the action of the igniter, the fuel starts to burn and generates flames. The flames heat the porous medium electrode and the combustion sleeve by radiation and convection, so that the droplets in the porous medium electrode and the droplets in the atomization area evaporate quickly. At the same time, the porous medium electrode heats the inner sleeve by radiation heat transfer to preheat the fuel, and sufficient heat exchange is carried out between the combustion sleeve and the gas in the cavity.

[0072] The flue gas generated by combustion first preheats the liquid fuel in the fuel tank, then fully exchanges heat with the air through the heat exchange sleeve, and then is discharged from the exhaust port, completing the entire combustion process.

[0073] The above embodiments are preferred implementation modes of the invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A micro-charged spray burner using porous dielectric electrodes, characterized in that: It includes an upper cover plate, a lower cover plate, an outer sleeve, a heat exchange sleeve, a flow distribution sleeve, a combustion sleeve, an inner sleeve, a porous medium electrode, an air inlet pipe, a primary air pipe, a secondary air pipe, a fuel liquid delivery pipe, a DC power supply and an igniter; The porous medium electrode is cylindrical, the top of the outer sleeve is sealed by the upper cover plate, the bottom of the outer sleeve is sealed by the lower cover plate, the heat exchange sleeve is located inside the outer sleeve, the outside of the heat exchange sleeve forms a flue gas channel, the combustion sleeve, the porous medium electrode and the inner sleeve are all located inside the heat exchange sleeve, an annular cavity is formed between the combustion sleeve and the heat exchange sleeve, the air inlet pipe passes through the outer sleeve and the heat exchange sleeve and extends into the cavity, the porous medium electrode is located below the combustion sleeve, the inside of the porous medium electrode and the inside of the combustion sleeve A combustion zone is formed, the inner sleeve is located outside the porous medium electrode, an annular atomization zone is formed between the inner sleeve and the porous medium electrode, the split sleeve is located between the inner sleeve and the heat exchange sleeve, a first interval is formed between the split sleeve and the inner sleeve, a second interval is formed between the split sleeve and the heat exchange sleeve, a primary air duct passes through the inner sleeve and the porous medium electrode, the cavity is connected to the combustion zone through the first interval and the primary air duct, the secondary air duct passes through the inner sleeve and the split sleeve, the cavity is connected to the atomization zone through the second interval and the secondary air duct; An annular fuel groove is formed inside the inner sleeve, a fuel delivery pipe passes through the outer sleeve, the heat exchange sleeve and the inner sleeve and extends into the fuel groove, a nozzle connected to the groove is provided on the inner wall of the inner sleeve, a positive electrode of the DC power supply is connected to the inner surface of the fuel groove, a negative electrode of the DC power supply is connected to the porous medium electrode, and an igniter is located in the combustion zone; The outer sleeve is provided with an exhaust port, the combustion zone is connected with the exhaust port through a smoke channel, and the heights of the air inlet pipe, the fuel liquid delivery pipe and the exhaust port on the outer sleeve decrease in sequence; The primary air duct is attached to the upper surface of the lower cover plate, the end of the primary air duct is arc-shaped, and the inner surface of the end of the primary air duct is tangent to the inner surface of the porous medium electrode.

2. The micro-charged spray burner using porous medium electrodes according to claim 1, characterized in that: It also includes a fuel tank and a fuel supply pump. The fuel tank is installed on the top of the upper cover plate, the fuel tank is connected to a fuel delivery pipe, and the fuel supply pump is installed on the fuel delivery pipe.

3. The micro-charged spray burner using porous medium electrodes according to claim 2, characterized in that: The heat exchange sleeve includes a cylindrical heat exchange sleeve body and an annular top cover located at the top end of the heat exchange sleeve body, and the combustion sleeve includes a cylindrical combustion sleeve body and an annular bottom plate located at the bottom end of the combustion sleeve body, so that the cross-section of the heat exchange sleeve is an inverted L-shape, the cross-section of the combustion sleeve is L-shaped, the top end of the combustion sleeve is connected to the inner edge of the annular top cover, and the top end of the porous medium electrode and the top end of the inner sleeve are both attached to the annular bottom plate.

4. The micro-charged spray burner using porous medium electrodes according to claim 2, characterized in that: There are four exhaust ports and four intake pipes respectively. The four intake pipes are evenly distributed in a circular shape, and the four intake pipes are aligned with the four exhaust ports up and down respectively.

5. The micro-charged spray burner using porous medium electrodes according to claim 2, characterized in that: The splitter sleeve has the same height as the inner sleeve and includes an upper section and a lower section. The outer diameter of the lower section is greater than the outer diameter of the upper section, thereby forming a step between the lower section and the upper section. The outer wall of the lower section is fitted and fixed to the inner wall of the heat exchange sleeve.

6. The micro-charged spray burner using porous medium electrodes according to claim 5, characterized in that: The secondary air duct is a straight tube structure and is perpendicular to the axis of the porous medium electrode. The secondary air duct passes through the upper section and the inner sleeve of the split sleeve.

7. The micro-charged spray burner using porous medium electrodes according to claim 6, characterized in that: The secondary air ducts and nozzles are distributed in several layers along the vertical direction, each layer of secondary air ducts includes 6 secondary air ducts distributed in a ring, and each layer of nozzles includes 6 nozzles distributed in a ring. On the horizontal projection plane, the secondary air ducts and nozzles are evenly staggered along the ring.

8. The micro-charged spray burner using porous medium electrodes according to claim 2, characterized in that: The distance between the nozzle and the porous medium electrode is less than 5 cm.

9. The combustion method of a micro-charged spray burner using a porous medium electrode according to any one of claims 2 to 8, characterized in that: The process includes the following: Turn on the DC power supply and the fuel supply pump. The liquid fuel in the fuel tank enters the fuel tank from the fuel delivery pipe under the push of the fuel supply pump, and then flows out of the nozzle. Under the action of the electric field force, the fuel droplets sprayed from the nozzle are broken into mist droplets and move to the porous medium electrode. Among them, most of the mist droplets pass through the porous medium electrode and enter the combustion zone, and a small part of the mist droplets hit the porous medium electrode; The air enters the cavity from the air inlet pipe, and then passes through the flow distribution of the splitter sleeve, and the air is divided into primary air and secondary air. The primary air swirls into the combustion zone from the first interval and the primary air duct, and the secondary air enters the atomization zone from the second interval and the secondary air duct, and then is premixed with the fuel in the atomization zone, and the droplets and evaporated fuel are blown out of the atomization zone and the porous medium electrode and enter the combustion zone; Under the action of the igniter, the fuel starts to burn and generates flames. The flames heat the porous medium electrode and the combustion sleeve by radiation and convection, so that the droplets in the porous medium electrode and the droplets in the atomization area evaporate quickly. At the same time, the porous medium electrode heats the inner sleeve by radiation heat transfer to preheat the fuel, and sufficient heat exchange is carried out between the combustion sleeve and the gas in the cavity. The flue gas generated by combustion first preheats the liquid fuel in the fuel tank, then fully exchanges heat with the air through the heat exchange sleeve, and then is discharged from the exhaust port, completing the entire combustion process.

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