Methanol engine air inlet injection system and injection method

Abstract

The invention belongs to the technical field of engine structures, and particularly relates to a methanol engine air inlet injection system and an injection method.The methanol engine air inlet injection system comprises a distribution air inlet pipe, the distribution air inlet pipe comprises an air inlet in the top and a plurality of air outlet manifolds at the bottom, and the air outlet manifolds are each provided with a plurality of air-assisted nozzles; an air heater is arranged in the distribution air inlet pipe, an air compressor, a methanol preheater and a methanol return device are arranged on the outer side of the distribution air inlet pipe, the air compressor is connected with a compressed air interface on the air-assisted nozzle, the methanol preheater is connected with a methanol inlet interface on the air-assisted nozzle, and the methanol return device is connected with a methanol return interface on the air-assisted nozzle. According to the invention, the air inlet injection system is innovatively used in the methanol engine, so that the atomization efficiency of methanol can be improved, and the diameter of injected methanol droplet particles is reduced, so that methanol is easier to form methanol steam due to a flash evaporation effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of engine structures, and in particular relates to an intake injection system and an injection method for a methanol engine. Background Art

[0002] Methanol is currently recognized worldwide as one of the most suitable green fuels. Methanol is not a traditional fossil fuel and does not require imported oil refining, significantly ensuring energy security. Methanol is also the ideal green energy source for high-power marine engines. It is significantly easier to store and transport than natural gas and ammonia, and its cost is significantly lower than diesel and natural gas. Methanol is currently being widely used as a fuel to replace fossil fuels, both domestically and internationally. However, dual-fuel systems, using both diesel and methanol, are still used, and the methanol-to-diesel substitution rate is less than 60%. Diesel, a traditional fuel, is consumed in high quantities and has a high cost.

[0003] At present, both domestic and foreign countries are researching high-power single methanol fuel engines with a methanol replacement rate of more than 90%. The main methanol injection schemes are direct injection using a pressure nozzle in the intake duct and direct injection into the cylinder. Both of these schemes currently have great defects.

[0004] The intake duct uses a conventional low-pressure nozzle for direct injection, resulting in low injection pressure and poor methanol atomization. Most of the methanol spray cannot enter the engine's combustion chamber and remains in the intake duct. Due to its low atomization level and high latent heat of vaporization, the methanol that does enter the combustion chamber is difficult to completely burn. Furthermore, the methanol remaining in the intake duct accumulates, forming runoff. When the intake or exhaust valve is opened, this runoff flows into the combustion chamber, resulting in incomplete methanol combustion, extinguishing the combustion chamber flame, and causing engine stalling. Furthermore, after entering the combustion chamber, the methanol flows into the engine oil sump as a liquid, mixing with the lubricating oil and causing lubricating oil emulsification.

[0005] Chinese patent CN118815610A discloses a dual-injector injection method for a methanol engine intake duct, which includes obtaining operating parameters through a detection device; calculating the methanol injection amount based on the operating parameters; and configuring a single injection or multiple injections according to predetermined injection parameter rules to achieve injection.

[0006] The aforementioned patent utilizes direct methanol injection, but the methanol nozzle is too large to be easily positioned on the engine cylinder head. Furthermore, the nozzle is difficult to manufacture and expensive. Furthermore, methanol is corrosive, making the lifespan of the nozzle difficult to guarantee. This presents numerous challenges during application.

[0007] Therefore, there is still a large gap between the two existing solutions in achieving the goals of production and normal loading and operation. Summary of the Invention

[0008] In view of the above deficiencies in the prior art, the technical problem to be solved by the present invention is: to provide a methanol engine intake injection system to achieve full combustion utilization of methanol, improve methanol combustion efficiency and nozzle service life, and reduce costs. The present invention also provides an injection method.

[0009] The technical solution adopted by the present invention to solve its technical problem is: The methanol engine intake injection system of the present invention includes a distribution intake pipe, which includes an air inlet at the top and multiple outlet manifolds at the bottom. The multiple outlet manifolds are respectively provided with multiple air-assisted nozzles. An air heater is provided inside the distribution intake pipe, and an air compressor, a methanol preheater and an alcohol return device are provided outside the distribution intake pipe. The air compressor is connected to the compressed air interface on the air-assisted nozzle, the methanol preheater is connected to the alcohol inlet interface on the air-assisted nozzle, and the alcohol return device is connected to the alcohol return interface on the air-assisted nozzle.

[0010] in: The distribution air intake pipe is divided into two parts, the upper part is an inverted funnel-shaped structure, and the lower part is a cylindrical structure. A heater fixing ring is provided at one end of the cylindrical structure. The air heater is arranged inside the cylindrical structure of the distribution air intake pipe, and the end of the air heater is fixedly connected to the heater fixing ring.

[0011] A nozzle holder is provided at the rear of the air outlet manifold, and the nozzle holder is connected to the air jet interface of the air-assisted nozzle.

[0012] The air heater is a hollow tube structure connected by two tubes, one end of which is a water inlet and the other end is a water outlet. The water inlet and the water outlet are both fixed on a fixed flange, which is connected to the heater fixing ring. Several heat sinks are provided on the hollow tube connected by two tubes.

[0013] The air compressor is arranged outside the funnel-shaped structure of the distribution air inlet pipe, and the methanol preheater and the methanol return device are arranged outside the cylindrical structure of the distribution air inlet pipe.

[0014] The air compressor is located above the methanol preheater and the alcohol return device, the methanol preheater and the alcohol return device are located above the air-assisted nozzle, and the alcohol return device is arranged outside the methanol preheater.

[0015] The air compressor is provided with an inner and outer layer, the inner layer is an air layer, and the outer layer is a heat exchange layer. An air inlet is provided at one end of the air layer, and several air outlets are provided on the side of the air layer. The air outlet passes through the heat exchange layer and is connected to the compressed air interface on the air-assisted nozzle through a pipeline; a heat exchange inlet is provided at one end of the heat exchange layer, and a heat exchange outlet is provided at the other end.

[0016] The methanol preheater is provided with an inner and outer double layer, the inner layer is an alcohol liquid layer, and the outer layer is a preheating layer. An alcohol liquid inlet is provided at one end of the alcohol liquid layer, and a plurality of alcohol liquid outlets are provided on the side of the alcohol liquid layer. The alcohol liquid outlets penetrate the preheating layer and are connected to the alcohol inlet interface on the air-assisted nozzle through pipelines; a preheating inlet is provided at one end of the preheating layer, and a preheating outlet is provided at the other end.

[0017] The side of the alcohol recycling device is provided with a plurality of alcohol recycling inlets, one side of the alcohol recycling device is provided with an alcohol recycling outlet, and the alcohol recycling inlets are connected to the alcohol recycling interface on the air-assisted nozzle through pipelines.

[0018] The injection method using the methanol engine intake injection system includes the following steps: A1. Start the engine. Air enters the intake injection system from the air intake. After being heated by the air heater, the air enters the exhaust manifold. A2. Compressed air enters the air compressor from the air inlet for heat exchange, and then enters the air-assisted nozzle from the air outlet through the compressed air interface; A3. Methanol fuel enters the methanol preheater from the alcohol liquid inlet for heat exchange, then enters the air-assisted nozzle from the alcohol liquid outlet through the alcohol inlet interface. The methanol fuel mixes with compressed air and is sprayed out from the jet interface as atomized methanol gas. The atomized methanol gas enters the outlet manifold, mixes with the heated air gas, and is vaporized and sprayed out. A4. The un-atomized methanol fuel in the air-assisted nozzle enters the alcohol recycle device through the alcohol recycle interface and the alcohol recycle inlet.

[0019] The beneficial effects of the present invention are: The present invention innovatively uses an intake injection system in a methanol engine, which can improve the atomization efficiency of methanol, reduce the diameter of the injected methanol droplets, and make it easier for methanol to form methanol vapor due to the flash evaporation effect.

[0020] The air-assisted nozzle mixes methanol fuel with compressed air, which can effectively improve the atomization degree of methanol fuel. The setting of the methanol recycle device can realize the recovery of unatomized methanol, preventing unatomized methanol from entering the engine, affecting methanol combustion, reducing engine efficiency and damaging the engine structure.

[0021] The invention can be fixed on the cylinder cover of the engine and can utilize the waste heat of the engine to heat and vaporize methanol, thereby greatly improving the thermal efficiency of the engine and reducing heat energy loss.

[0022] The air heater, the heat exchange layer of the air compressor and the preheating layer of the methanol preheater of the present invention all utilize the high-temperature cooling water of the engine to heat methanol, compressed air and air gas at the same time, which can effectively improve the vaporization rate of methanol, make combustion more stable, reduce resource waste and realize water recycling.

[0023] The present invention sprays atomized methanol into the intake manifold, and the atomized methanol is mixed with heated air gas, so that the atomized methanol is quickly vaporized and started by spark plug ignition. The methanol replacement rate reaches 100%, avoiding misfire in the cylinder or methanol escape, making the engine speed regulation performance faster, and effectively improving the engine speed regulation efficiency.

[0024] The present invention recovers the un-atomized methanol through the alcohol recycling device, thereby avoiding the formation of liquid runoff of methanol into the combustion chamber, and preventing the flame from being extinguished or emulsified with the engine oil. The present invention has the characteristics of low cost and strong usability, and is easy to implement. The present invention is small in size and compact in structure, and can be directly installed on the engine cylinder head. It can improve the combustion rate without affecting the engine operation, and effectively improve the thermal efficiency of the engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of the present invention; Figure 2 It is a left-side structural schematic diagram of the present invention; Figure 3 This is a schematic diagram of the structure of the distribution intake pipe of the present invention; Figure 4 It is a schematic structural diagram of the air heater of the present invention; Figure 5 It is a schematic structural diagram of the air compressor of the present invention; Figure 6 It is a schematic cross-sectional view of the air compressor of the present invention; Figure 7 This is a schematic structural diagram of the methanol preheater of the present invention; Figure 8 This is a schematic cross-sectional structural diagram of a methanol preheater according to the present invention; Figure 9 This is a schematic structural diagram of the alcohol recycling device of the present invention; Figure 10 This is a schematic diagram of the structure of the air-assisted nozzle of the present invention; Figure 11 It is a schematic diagram of part of the connection structure of the present invention.

[0026] In the figure: 1. Distribution inlet pipe; 2. Air heater; 3. Air compressor; 4. Methanol preheater; 5. Alcohol return device; 6. Air-assisted nozzle; 101. Air inlet; 102. Heater fixing ring; 103. Exhaust manifold; 104. Nozzle holder; 201. Water inlet; 202. Water outlet; 203. Fixing flange; 204. Heat sink; 301. Air layer; 302. Air inlet; 303. Heat exchange inlet; 304. Air outlet; 305. Heat exchange layer; 306. Heat exchange outlet; 401. Alcohol liquid layer; 402. Alcohol liquid inlet; 403. Preheating inlet; 404. Alcohol liquid outlet; 405. Preheating layer; 406. Preheating outlet; 501. Alcohol return inlet; 502. Alcohol return outlet; 601. Jet interface; 602. Compressed air interface; 603. Alcohol inlet interface; 604. Alcohol return interface. DETAILED DESCRIPTION

[0027] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0028] Example 1 like Figure 1-11 As shown, the methanol engine intake injection system of the present invention includes a distribution intake pipe 1, which includes an air inlet 101 at the top and several outlet manifolds 103 at the bottom. Several air-assisted nozzles 6 are respectively provided on the several outlet manifolds 103. An air heater 2 is provided inside the distribution intake pipe 1, and an air compressor 3, a methanol preheater 4 and an alcohol return device 5 are provided outside the distribution intake pipe 1. The air compressor 3 is connected to the compressed air interface 602 on the air-assisted nozzle 6, the methanol preheater 4 is connected to the alcohol inlet interface 603 on the air-assisted nozzle 6, and the alcohol return device 5 is connected to the alcohol return interface 604 on the air-assisted nozzle 6.

[0029] The distribution air intake pipe 1 is divided into two parts, the upper part is an inverted funnel-shaped structure, and the lower part is a cylindrical structure. A heater fixing ring 102 is provided at one end of the cylindrical structure. The air heater 2 is arranged inside the cylindrical structure of the distribution air intake pipe 1, and the end of the air heater 2 is fixedly connected to the heater fixing ring 102.

[0030] A nozzle holder 104 is provided at the rear of the air outlet manifold 103 , and the nozzle holder 104 is connected to the air injection interface 601 of the air-assisted nozzle 6 .

[0031] The air heater 2 is a hollow tube structure with two tubes connected, one end of which is a water inlet 201 and the other end is a water outlet 202. The water inlet 201 and the water outlet 202 are both fixed on a fixed flange 203, and the fixed flange 203 is connected to the heater fixing ring 102. A number of heat sinks 204 are provided on the hollow tube with two tubes connected.

[0032] The air compressor 3 is arranged outside the funnel-shaped structure of the distribution air inlet pipe 1, and the methanol preheater 4 and the methanol return device 5 are arranged outside the cylindrical structure of the distribution air inlet pipe 1.

[0033] The air compressor 3 is located above the methanol preheater 4 and the alcohol recycling device 5 . The methanol preheater 4 and the alcohol recycling device 5 are located above the air-assisted nozzle 6 . The alcohol recycling device 5 is arranged outside the methanol preheater 4 .

[0034] The air compressor 3 is provided with an inner and outer layer, the inner layer is an air layer 301, and the outer layer is a heat exchange layer 305. An air inlet 302 is provided at one end of the air layer 301, and a plurality of air outlets 304 are provided on the side of the air layer 301. The air outlets 304 pass through the heat exchange layer 305 and are connected to the compressed air interface 602 on the air-assisted nozzle 6 through a pipeline; a heat exchange inlet 303 is provided at one end of the heat exchange layer 305, and a heat exchange outlet 306 is provided at the other end.

[0035] The methanol preheater 4 is provided with an inner and outer layer, the inner layer is an alcohol liquid layer 401, and the outer layer is a preheating layer 405. An alcohol liquid inlet 402 is provided at one end of the alcohol liquid layer 401, and several alcohol liquid outlets 404 are provided on the side of the alcohol liquid layer 401. The alcohol liquid outlets 404 pass through the preheating layer 405 and are connected to the alcohol inlet interface 603 on the air-assisted nozzle 6 through a pipeline; a preheating inlet 403 is provided at one end of the preheating layer 405, and a preheating outlet 406 is provided at the other end.

[0036] A plurality of alcohol return inlets 501 are provided on the side of the alcohol return device 5 , and an alcohol return outlet 502 is provided on one side of the alcohol return device 5 . The alcohol return inlets 501 are connected to the alcohol return interface 604 on the air-assisted nozzle 6 through a pipeline.

[0037] The water inlet 201 of the air heater 2, the heat exchange inlet 303 of the air compressor 3 and the preheating inlet 403 of the methanol preheater 4 are all connected to the high-temperature cooling water outlet of the engine, providing high-temperature water for heating the air and methanol fuel in the injection system. The heat-exchanged water is then connected to the water tank of the engine and flows back into the water tank of the engine for cooling the engine, thereby realizing recycling.

[0038] The injection method using the methanol engine intake injection system includes the following steps: A1. The intake manifold 103 on the air distribution intake pipe 1 is fixed to the cylinder head of a single-fuel methanol engine. The engine is started, and air enters the intake injection system from the air intake port 101. The air heater 2 is arranged inside the air distribution intake pipe 1 to heat the air. After being heated by the air heater 2, the air enters the outlet manifold 103. A2, compressed air enters the air compressor 3 from the air inlet 302 for heat exchange, and then enters the air-assisted nozzle 6 from the air outlet 304 through the compressed air interface 602 to provide compressed air for atomizing methanol; A3. Methanol fuel enters the methanol preheater 4 from the alcohol liquid inlet 402 for heat exchange, then enters the air-assisted nozzle 6 from the alcohol liquid outlet 404 through the alcohol inlet port 603 for atomization and injection. The methanol fuel mixes with compressed air and is ejected from the injection port 601 as atomized methanol gas. The atomized methanol gas enters the outlet manifold 103, mixes with the heated air gas, and is vaporized and ejected for combustion of the methanol fuel. A4. The un-atomized methanol fuel in the gas-assisted nozzle 6 enters the alcohol recycling device 5 through the alcohol recycling interface 604 and the alcohol recycling inlet 501, and the excess methanol is recycled and reused.

Claims

1. A methanol engine intake injection system, comprising a distribution intake pipe (1), characterized in that: The distribution air inlet pipe (1) includes an air inlet (101) at the top and a plurality of air outlet manifolds (103) at the bottom. The plurality of air outlet manifolds (103) are respectively provided with a plurality of air-assisted nozzles (6). An air heater (2) is provided inside the distribution air inlet pipe (1). An air compressor (3), a methanol preheater (4) and an alcohol return device (5) are provided outside the distribution air inlet pipe (1). The air compressor (3) is connected to a compressed air interface (602) on the air-assisted nozzle (6), the methanol preheater (4) is connected to an alcohol inlet interface (603) on the air-assisted nozzle (6), and the alcohol return device (5) is connected to an alcohol return interface (604) on the air-assisted nozzle (6).

2. The methanol engine intake injection system according to claim 1, characterized in that: The distribution air inlet pipe (1) is divided into two parts, the upper part is an inverted funnel-shaped structure, and the lower part is a cylindrical structure. A heater fixing ring (102) is provided at one end of the cylindrical structure. The air heater (2) is provided inside the cylindrical structure of the distribution air inlet pipe (1), and the end of the air heater (2) is fixedly connected to the heater fixing ring (102).

3. The methanol engine intake injection system according to claim 1, characterized in that: A nozzle holder (104) is provided at the rear of the air outlet manifold (103), and the nozzle holder (104) is connected to the air injection interface (601) of the air-assisted nozzle (6).

4. The methanol engine intake injection system according to claim 2, characterized in that: The air heater (2) is a double-tube connected hollow tube structure, one end of which is a water inlet (201) and the other end is a water outlet (202), the water inlet (201) and the water outlet (202) are both fixed on a fixed flange (203), the fixed flange (203) is connected to the heater fixing ring (102), and a plurality of heat sinks (204) are provided on the double-tube connected hollow tube.

5. The methanol engine intake injection system according to claim 2, characterized in that: The air compressor (3) is arranged outside the funnel-shaped structure of the distribution air inlet pipe (1), and the methanol preheater (4) and the methanol return device (5) are arranged outside the cylindrical structure of the distribution air inlet pipe (1).

6. The methanol engine intake injection system according to claim 1, characterized in that: The air compressor (3) is located above the methanol preheater (4) and the alcohol return device (5), the methanol preheater (4) and the alcohol return device (5) are located above the air-assisted nozzle (6), and the alcohol return device (5) is arranged outside the methanol preheater (4).

7. The methanol engine intake injection system according to claim 1, characterized in that: The air compressor (3) is provided with an inner and outer layer, the inner layer is an air layer (301), and the outer layer is a heat exchange layer (305). An air inlet (302) is provided at one end of the air layer (301), and a plurality of air outlets (304) are provided on the side of the air layer (301). The air outlets (304) penetrate the heat exchange layer (305) and are connected to the compressed air interface (602) on the air-assisted nozzle (6) through a pipeline. A heat exchange inlet (303) is provided at one end of the heat exchange layer (305), and a heat exchange outlet (306) is provided at the other end.

8. The methanol engine intake injection system according to claim 1, characterized in that: The methanol preheater (4) is provided with an inner and outer double layer, the inner layer being an alcohol liquid layer (401), and the outer layer being a preheating layer (405). An alcohol liquid inlet (402) is provided at one end of the alcohol liquid layer (401), and a plurality of alcohol liquid outlets (404) are provided at the side of the alcohol liquid layer (401). The alcohol liquid outlets (404) penetrate the preheating layer (405) and are connected to the alcohol inlet interface (603) on the air-assisted nozzle (6) through a pipeline. A preheating inlet (403) is provided at one end of the preheating layer (405), and a preheating outlet (406) is provided at the other end.

9. The methanol engine intake injection system according to claim 1, characterized in that: A plurality of alcohol return inlets (501) are provided on the side of the alcohol return device (5), and an alcohol return outlet (502) is provided on one side of the alcohol return device (5). The alcohol return inlet (501) is connected to the alcohol return interface (604) on the air-assisted nozzle (6) through a pipeline.

10. An injection method using the methanol engine intake injection system according to any one of claims 1 to 9, characterized in that: The following steps are involved: A1. Start the engine, and the air enters the intake injection system from the air intake (101). The air is heated by the air heater (2) and then enters the exhaust manifold (103); A2, compressed air enters the air compressor (3) from the air inlet (302) for heat exchange, and then enters the air-assisted nozzle (6) from the air outlet (304) through the compressed air interface (602); A3, methanol fuel enters the methanol preheater (4) from the alcohol liquid inlet (402) for heat exchange, then enters the air-assisted nozzle (6) from the alcohol liquid outlet (404) through the alcohol inlet interface (603), the methanol fuel is mixed with compressed air and sprayed out from the jet interface (601) as atomized methanol gas, the atomized methanol gas enters the outlet manifold (103) and mixes with the heated air gas, and is vaporized and sprayed out; A4. The un-atomized methanol fuel in the air-assisted nozzle (6) enters the alcohol return device (5) through the alcohol return interface (604) and the alcohol return inlet (501).

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