Methanol injection method, device and calibration method for methanol engine

Abstract

The application discloses a methanol injection method of a methanol engine, relates to the methanol engine, and transmits methanol fuel sprayed from a methanol nozzle in a spiral transmission mode to separate atomized methanol fuel from methanol droplets, wherein the atomized methanol fuel is transported into a combustion chamber, and the methanol droplets are transported to a methanol nozzle injection side to be heated and evaporated. The application further discloses a methanol injection device and a calibration method of the methanol engine. The application fully utilizes the energy of air to evaporate the methanol droplets, guarantees the evaporation effect of methanol particles, and improves the atomization efficiency of the suspended droplet particles.

Description

Technical Field

[0001] This invention relates to methanol engines, and more specifically, to a methanol injection method, apparatus, and calibration method for a methanol engine. Background Technology

[0002] Current methanol engines generally use M100 methanol (i.e., pure methanol) as the primary fuel, and combustion is achieved through intake manifold injection and spark plug ignition. However, when the ambient temperature drops to 16°C or below, combustion cannot be achieved solely through methanol injection, thus requiring auxiliary starting methods. The main reasons for this problem include: First, methanol has a high latent heat of atomization, more than three times that of gasoline, causing it to absorb a large amount of heat at low temperatures, making it difficult to form a sufficient combustible mixture; second, methanol has a low saturated vapor pressure, much lower than gasoline, which limits methanol evaporation and reduces the amount of methanol vapor in the cylinder; finally, methanol has a high flash point and ignition temperature, and in low-temperature environments, due to the endothermic effect during evaporation, the ambient temperature inside the cylinder may drop below the flash point temperature of methanol.

[0003] To address the above issues, current industry solutions include:

[0004] 1) When the temperature is below 16℃, use gasoline injection to assist starting. After the engine is warmed up, inject methanol.

[0005] 2) By adopting air-assisted nozzle technology, the particle size of the sprayed liquid droplets is reduced from 60-150μm to 7-9μm, so that the methanol engine can still achieve cold start at 5℃;

[0006] 3) It adopts direct injection, and the minimum cold start temperature is 5℃;

[0007] 4) Heat the coolant to above 30°C, so that it can be successfully started at an ambient temperature of -30°C;

[0008] 5) Intake air heating, which can extend the cold start temperature to -12℃.

[0009] However, as Figure 1 As shown, traditional injectors form an angle of 30 to 60 degrees with the airflow direction, injecting methanol droplets at an angle. However, the droplets cannot achieve uniform distribution within the pipe; large methanol droplets concentrate at the bottom of the pipe, resulting in a small wetted wall area and difficulty in evaporation. Therefore, while the above method can start a methanol engine normally, it still cannot solve the problem of large methanol droplets concentrating at the bottom of the pipe and failing to evaporate. Summary of the Invention

[0010] The technical problem to be solved by the present invention is to provide a methanol injection method, apparatus and calibration method for a methanol engine, which addresses the shortcomings of the prior art.

[0011] The methanol injection method for a methanol engine described in this invention involves conveying methanol fuel injected from a methanol nozzle in a spiral conveying manner to separate the atomized methanol fuel and methanol droplets. The atomized methanol fuel is transported to the combustion chamber, while the methanol droplets are transported to the methanol nozzle injection side for heating and evaporation.

[0012] Preferably, a rotating flow field is created in the air intake pipe in the opposite direction of the methanol nozzle injection direction, and the methanol fuel is spirally transported by blowing the methanol fuel injected from the methanol nozzle through the rotating flow field.

[0013] Preferably, a heating zone is constructed in the air intake pipe on the injection direction side of the methanol nozzle, and the heating zone protrudes from the inner wall of the air intake pipe to prevent the accumulation of methanol droplets.

[0014] Preferably, the temperature of the heating zone is 70℃-100℃.

[0015] Preferably, the injection direction of the methanol nozzle is consistent with the axial direction of the air intake pipe.

[0016] A methanol injection apparatus for implementing the methanol injection method, characterized in that it comprises:

[0017] A fan, installed on the opposite side of the methanol nozzle's injection direction, is used to generate a rotating flow field;

[0018] Methanol nozzle, used for injecting methanol fuel;

[0019] The heating unit, installed in the air inlet pipe on the side of the methanol nozzle in the direction of injection, is used to heat and evaporate the methanol droplets.

[0020] Preferably, the heating unit includes a plurality of heaters, which are evenly arranged around the inner wall of the air intake pipe and protrude from the inner wall of the air intake pipe.

[0021] Preferably, all the heaters are fixedly mounted on a heat-conducting sleeve, which is fixedly mounted on the inner wall of the air inlet pipe to form a blocking surface for the methanol droplets.

[0022] Preferably, the heat-conducting sleeve is a copper sleeve, and the thickness of the heat-conducting sleeve on the side near the nozzle is less than the thickness of the other side.

[0023] A calibration method for calibrating the fan speed and heater power in the methanol injection device includes the following steps:

[0024] Step 1: Place the methanol engine equipped with the methanol injection device on the test bench;

[0025] The second step is to set the airflow rate and air temperature at the air inlet of the air intake pipe to simulate different operating conditions of the methanol engine.

[0026] The third step is to run the methanol engine at the intake flow rate and intake temperature set in the second step, and control the methanol nozzle to inject methanol fuel according to the set injection amount. At the same time, monitor the number of droplets in the intake pipe on the side of the heating unit away from the methanol nozzle; adjust the fan speed and heater power, and take the fan speed and heater power at the time when the number of droplets is the smallest and the temperature of the heat-conducting jacket does not exceed the set safety limit as the calibration value.

[0027] Beneficial effects

[0028] The advantages of this invention are:

[0029] 1. By creating a rotating flow field through disturbed horizontal airflow, the airflow spirals within the intake pipe. Under the influence of this rotating flow field, the methanol droplets ejected from the nozzle not only evaporate more rapidly, but also, due to centrifugal force, experience greater inertia and collide with the pipe wall. Meanwhile, the atomized methanol fuel, with its lower inertia, flows forward within the rotating flow field, thus achieving separation between the methanol droplets and the atomized methanol fuel. Furthermore, the energy of the air is fully utilized for the evaporation of the methanol droplets, ensuring effective methanol particle evaporation.

[0030] 2. The design of the heating unit enables the heating and evaporation of methanol droplets, while avoiding the problem of methanol droplets passing through the heating zone along the inlet pipe wall without being completely evaporated and atomized. This significantly enhances the evaporation capacity and efficiency of methanol droplets. Furthermore, the disturbance effect of the rotating flow field disrupts the original laminar boundary layer on the inlet pipe wall, enhancing the convective heat transfer coefficient between the airflow and the heating unit. This process not only promotes the rapid evaporation of methanol droplets but also improves the atomization efficiency of suspended droplet particles by heating the inlet airflow.

[0031] 3. The methanol nozzle's spray direction is completely aligned with the airflow direction and is located at the center of the pipe. This design allows methanol to be sprayed evenly in all directions, effectively achieving uniform distribution of the sprayed droplets within the pipe and fully utilizing the energy of the incoming air to promote the evaporation of the methanol droplets. Attached Figure Description

[0032] Figure 1 A schematic diagram of a traditional methanol injector installation structure;

[0033] Figure 2a This is an axial view of a traditional methanol fuel injection method within the intake manifold.

[0034] Figure 2b An axial view of methanol fuel injection in the intake manifold according to the present invention;

[0035] Figure 3 This is a schematic diagram of the installation structure of the heater and heat-conducting sleeve of the present invention;

[0036] Figure 4 This is a schematic diagram of the installation structure of the methanol injection device of the present invention;

[0037] Figure 5 This is a schematic diagram of the installation structure of the methanol injection device used in the calibration method of the present invention;

[0038] Figure 6 This is a calibration test record table for the fan speed and heater temperature of the present invention. Detailed Implementation

[0039] The present invention will be further described below with reference to embodiments, but this does not constitute any limitation on the present invention. Any limited modifications made by any person within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0040] This invention discloses a methanol injection method for a methanol engine, in which methanol fuel injected from a methanol nozzle is conveyed via a helical conveyor. This helical conveyor allows the injected methanol fuel to have centrifugal force, causing heavier droplets to impact the inner wall of the intake pipe, while smaller particles and atomized methanol fuel remain suspended in the pipe. As the fluid moves forward, these particles continue to evaporate during subsequent flow, thus achieving separation of the atomized methanol fuel and methanol droplets. Furthermore, the helical conveyor method has the advantage of allowing methanol droplets to be more evenly distributed on the inner wall of the intake pipe. Figure 2a and Figure 2b As shown, where, Figure 2a This is an axial view of the traditional methanol fuel injection method in the intake manifold. It can be seen that a large amount of air does not intersect with the liquid droplet injection area, resulting in wasted air energy. Furthermore, simply increasing the number of nozzles results in the liquid droplet clusters on both sides being too close to the pipe wall, causing a large amount of dense liquid to collide with the wall, leading to poor evaporation. Figure 2b This is an axial view of the methanol fuel injection in the intake pipe according to the present invention. As can be seen from the figure, the methanol droplets are evenly distributed and the methanol droplets are in full contact with the air, making full use of the energy of the air to evaporate the methanol droplets and ensuring the evaporation effect of the methanol particles.

[0041] Specifically, in this embodiment, a rotating flow field is created in the air intake pipe in the opposite direction of the methanol nozzle's injection direction. This rotating flow field blows the methanol fuel injected from the methanol nozzle into a spiral transport, thereby achieving spiral transport of the injected methanol fuel. This eliminates the need for extensive modifications to the methanol nozzle, significantly reducing costs.

[0042] The atomized methanol fuel is delivered to the combustion chamber, and the methanol droplets are delivered to the methanol nozzle injection side for heating and evaporation. This allows the methanol droplets to be rapidly evaporated and atomized, enabling sufficient methanol fuel to accumulate in the combustion chamber of the methanol engine within an extremely short time, which is very beneficial for the cold start of the methanol engine.

[0043] Specifically, a heating zone is constructed in the intake pipe on the side of the methanol nozzle in the injection direction, and the heating zone protrudes from the inner wall of the intake pipe to prevent the accumulation of methanol droplets. This design not only achieves the heating and evaporation of methanol droplets, but also avoids the problem of droplets passing through the heating zone along the pipe wall of the intake pipe without being completely evaporated and atomized, greatly enhancing the evaporation capacity and efficiency of methanol droplets.

[0044] In this embodiment, the temperature of the heating zone is 70℃-100℃, which is conducive to the evaporation of methanol droplets.

[0045] Furthermore, the methanol nozzle's spray direction is aligned with the axis of the intake pipe. Traditional methanol injectors operate at an angle of 30°-60° to the airflow direction, resulting in oblique methanol injection and making it difficult to achieve uniform distribution of droplets within the pipe. In contrast, the methanol nozzle of this invention utilizes a 90° bend in conjunction with the nozzle, aligning the nozzle's spray direction with the airflow direction and positioning it at the center of the intake pipe. This allows for the spraying of methanol fuel in all directions, coupled with a rotating flow field, achieving uniform distribution of methanol droplets within the intake pipe and fully utilizing the energy of the intake air for methanol droplet evaporation. This combination of maximizing intake air energy utilization and heating evaporation enables rapid evaporation and atomization of methanol droplets.

[0046] A methanol injection device for implementing the above-described methanol injection method, such as... Figure 3 As shown, it includes a fan 2, a methanol nozzle 3, and a heating unit.

[0047] The fan 2 is installed on the opposite side of the methanol nozzle 3's injection direction to generate a rotating flow field. The methanol nozzle 3 is used to inject methanol fuel, and it is connected to a 90° bend, so that the methanol nozzle's injection direction is consistent with the airflow direction and is located at the center of the intake pipe. The heating unit is installed in the intake pipe 1 on the side of the methanol nozzle 3's injection direction to heat and evaporate the methanol droplets.

[0048] Specifically, such as Figure 4As shown, the heating unit includes multiple heaters 4, which are evenly arranged around the inner wall of the intake pipe 1, and each heater 4 protrudes from the inner wall of the intake pipe 1. All heaters 4 are fixedly mounted on a heat-conducting sleeve 5, and the heat-conducting sleeve 5 is heated by the heaters 4. The heat-conducting sleeve 5 is fixedly mounted on the inner wall of the intake pipe 1 to form a blocking surface for methanol droplets. Through the blocking effect of the heat-conducting sleeve 5 and its protruding design with the heaters 4, the blocked methanol droplets and those that collide with it can be heated and thus rapidly evaporated.

[0049] Preferably, the heat-conducting sleeve 5 is a copper sleeve, and the thickness of the heat-conducting sleeve 5 on the side near the nozzle is less than the thickness of the other side. That is, the inner ring of the heat-conducting sleeve 5 has a sloping structure with one side higher than the other, which allows it to have a larger area and better capture methanol droplets.

[0050] A calibration method for calibrating the fan speed and heater power in the aforementioned methanol injection device, such as... Figure 5 As shown, the method includes the following steps:

[0051] The first step involves placing the methanol engine equipped with a methanol injection device on a test bench and adding a flow meter 6 at the inlet of the intake pipe 1 to measure the gas flow rate and temperature. This flow meter is used to control the test conditions. A thermometer is placed on the copper sleeve to monitor its temperature and prevent it from exceeding the safe temperature limit. A liquid particle measuring device 7 is installed at the outlet of the intake pipe 1; the results are used to evaluate the methanol atomization and evaporation effect.

[0052] The second step involves setting the intake flow rate and temperature at the intake port of intake pipe 1 to simulate different operating conditions of the methanol engine. Taking intake inlet flow rates of 100 kg / h and 150 kg / h, and temperatures of 0°C and 5°C as examples, the flow rate and temperature for each operating condition are determined to be 100 kg / h@0°C, 150 kg / h@0°C, 100 kg / h@5°C, and 150 kg / h@5°C. The third step involves testing the flow rate and temperature for each of these operating conditions individually.

[0053] The third step involves operating the methanol engine at the intake flow rate and temperature set in the second step, and controlling the methanol nozzle 3 to inject methanol fuel according to the set injection quantity. Simultaneously, the number of droplets in the intake pipe 1 on the side of the heating unit furthest from the methanol nozzle 3 is monitored. The fan speed 2 and heater power 4 are adjusted, and the fan speed and heater power at the moment when the number of droplets is minimal and the temperature of the heat-conducting jacket 5 does not exceed the set safety limit are taken as calibration values.

[0054] The final test record sheet is as follows Figure 6As shown, the fan speed and heater power under different intake boundaries and methanol injection quantities can be obtained, thereby ensuring that the methanol engine can achieve optimal atomization evaporation under any cold start condition and guarantee the cold start performance of the methanol engine.

[0055] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention, and these will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A calibration method for calibrating fan speed and heater power of a methanol injection device, characterized by, The methanol injection device comprises: a fan (2) installed on the opposite side of the methanol nozzle (3) in the direction of the injection for generating a rotating flow field; a methanol nozzle (3) for injecting methanol fuel; a heating unit installed in the intake pipe (1) on the side of the methanol nozzle (3) in the direction of the injection for heating and evaporating the methanol droplets; the heating unit comprises a plurality of heaters (4); all the heaters (4) are fixedly installed on a heat conduction sleeve (5); the method comprises the following steps: Step 1: place the methanol engine equipped with the methanol injection device on a test bench; Step 2: set the intake flow rate and intake temperature at the intake port of the intake pipe (1) to simulate different operating conditions of the methanol engine; Step 3: operate the methanol engine at the intake flow rate and intake temperature set in Step 2, control the methanol nozzle (3) to inject methanol fuel at the set injection amount, and monitor the number of droplets in the intake pipe (1) on the side away from the methanol nozzle (3); adjust the rotational speed of the fan (2) and the power of the heater (4) to obtain the rotational speed of the fan and the power of the heater at the moment when the number of droplets is the least and the temperature of the heat conduction sleeve (5) does not exceed the set safety limit as the calibration value.

2. The calibration method for calibrating fan speed and heater power of a methanol injection device according to claim 1, characterized in that, A plurality of the heaters (4) are evenly arranged around the inner wall of the intake pipe (1), and the heaters (4) protrude from the inner wall of the intake pipe (1).

3. A calibration method for calibrating fan speed and heater power of a methanol injection device according to claim 2, characterized in that, The heat conduction sleeve (5) is fixedly installed on the inner wall of the intake pipe (1) to form a blocking surface for the methanol droplets.

4. The calibration method for calibrating fan speed and heater power of a methanol injection device according to claim 3, characterized in that, The heat conduction sleeve (5) is a copper sleeve, and the thickness of the side of the heat conduction sleeve (5) close to the nozzle is less than the thickness of the other side.

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