CN111237066B - Device and method for reducing heat load of natural gas engine by doping alcohol - Google Patents
Device and method for reducing heat load of natural gas engine by doping alcohol Download PDFInfo
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
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- F02D19/105—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed simultaneously using pluralities of fuels peculiar to compression-ignition engines in which the main fuel is gaseous operating in a special mode, e.g. in a liquid fuel only mode for starting
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- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
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- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
- F02D19/0639—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed characterised by the type of fuels
- F02D19/0642—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed characterised by the type of fuels at least one fuel being gaseous, the other fuels being gaseous or liquid at standard conditions
- F02D19/0647—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed characterised by the type of fuels at least one fuel being gaseous, the other fuels being gaseous or liquid at standard conditions the gaseous fuel being liquefied petroleum gas [LPG], liquefied natural gas [LNG], compressed natural gas [CNG] or dimethyl ether [DME]
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- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
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- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/14—Introducing closed-loop corrections
- F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
- F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
- F02D41/1454—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an oxygen content or concentration or the air-fuel ratio
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- F02D41/22—Safety or indicating devices for abnormal conditions
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- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/30—Controlling fuel injection
- F02D41/3094—Controlling fuel injection the fuel injection being effected by at least two different injectors, e.g. one in the intake manifold and one in the cylinder
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- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
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- F02D2200/00—Input parameters for engine control
- F02D2200/02—Input parameters for engine control the parameters being related to the engine
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- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
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- F02D2200/00—Input parameters for engine control
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- F02D2200/04—Engine intake system parameters
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- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D2200/00—Input parameters for engine control
- F02D2200/02—Input parameters for engine control the parameters being related to the engine
- F02D2200/10—Parameters related to the engine output, e.g. engine torque or engine speed
- F02D2200/101—Engine speed
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Abstract
The invention discloses a device and a method for reducing the heat load of a natural gas engine by alcohol doping, which carry out closed-loop control on the injection quantity of natural gas and alcohol fuels by using an actual excess air coefficient measured by a wide-range oxygen sensor, so that the engine stably runs under a target excess air coefficient and any alcohol fuel mixing combustion proportion, thereby reducing the heat load of the natural gas engine by the way of alcohol doping, creating conditions for further improving the compression ratio of the engine, further increasing the heat efficiency of the natural gas engine and reducing the hydrocarbon emission.
Description
Technical Field
The invention belongs to the technical field of engine alternative fuels, and particularly relates to a control system for reducing the heat load of a natural gas engine by blending alcohol.
Background
The energy and environmental problems are severe day by day, and the theories and the technologies of energy conservation and emission reduction of the internal combustion engine are promoted to be continuously improved. High efficiency, cleanliness and energy conservation are the development goals of advanced internal combustion engines. The adoption of low-carbon fuel in combination with advanced combustion technology is one of the important ways to realize the energy conservation and emission reduction of the internal combustion engine. Natural gas and alcohol fuels are two low carbon fuels with great development potential. Natural gas is widely used in spark-ignition and compression-ignition engines due to its large reserves, high octane number, low particulate emissions, and low price.
Natural gas engines face the following problems: firstly, natural gas is gas fuel, the density is low, and the air inlet channel injection occupies the volume of part of fresh air, so that the engine charge is reduced, and the power is reduced; secondly, the flame propagation speed of natural gas is low, and the ignition energy is high, so that the rapid combustion period is prolonged, the combustion isochoricity is reduced, and the thermal efficiency of the engine is reduced; in addition, in the face of increasingly strict emission regulations, natural gas engines mostly adopt an equivalence ratio combustion mode, and in the combustion mode, the concentration of mixed gas is high, the combustion temperature in an engine cylinder is high, so that the heat load and the exhaust temperature in the cylinder are high, and the effective thermal efficiency of the engine is reduced.
The alcohol fuel comprises methanol, ethanol and n-butanol. The methanol can be synthesized by taking coal and biomass as raw materials and capturing CO in air 2 And hydrogenation synthesis; the ethanol can also be synthesized by taking biomass as a raw material; the n-butanol can also be synthesized from fossil fuels and biomass. The alcohol fuel (methanol, ethanol and n-butyl alcohol) is liquid at normal temperature and normal pressure, and is easy to store and transport; the alcohol fuel has larger latent heat of vaporization, and the intake temperature of the engine can be reduced after the injection of an air inlet channel or in-cylinder injection, thereby being beneficial to increasing the engine charge, reducing the in-cylinder combustion temperature and reducing the heat load of the engine; the flame propagation speed of the alcohol fuel is high, the ignition energy is low, and the combustion isochoricity can be increased, so that the improvement of the effective thermal efficiency of an engine is facilitated; the alcohol fuel is oxygen-containing fuel, so that the combustion is more sufficient, the harmful emissions are reduced, the combustion speed of the mixed gas is accelerated after the natural gas is mixed with the alcohol fuel, and the unburned hydrocarbon emission can be further reduced.
Although natural gas and alcohol fuels (methanol, ethanol and n-butyl alcohol) have complementarity in the aspect of combustion characteristics, because there is a certain difficulty in flexibly adjusting the ECU control strategy according to the injected different alcohol fuels (methanol, ethanol and n-butyl alcohol), the natural gas engine mainly uses co-combustion methanol (for example, 201410498626.X) at present, and the control strategy for co-combustion methanol uses the engine temperature as a feedback signal, so that the co-combustion proportion of methanol is not accurately controlled, and the stable operation of the engine cannot be ensured.
Disclosure of Invention
The invention aims to provide a device and a method for reducing the heat load of a natural gas engine by mixing alcohol.
In order to achieve the purpose, the invention adopts the following technical scheme:
a device for reducing the thermal load of natural gas engine by mixing alcohol, which comprises an electric control system andthe actuator comprises a natural gas nozzle and an alcohol fuel nozzle which are respectively arranged at the side (in front of the throttle valve) far away from the cylinder and the side (behind the throttle valve) close to the cylinder of the engine throttle valve, the electronic control system comprises an ECU and sensors which are connected with the ECU and are used for respectively measuring the rotating speed of the engine, the running phase and timing of the engine, the inlet air temperature and pressure of the engine and the exhaust oxygen concentration of the engine, and the ECU is used for measuring the rotating speed, the running phase and timing of the engine, the inlet air temperature and pressure of the engine and the exhaust oxygen concentration of the engine according to the actual excess air coefficient (lambda) actual ) Energy Substitution Rate (AESR) and target excess air factor (λ) for reference target alcohols theory ) The determined natural gas injection quantity and the alcohol fuel injection quantity are respectively corrected to generate injection pulse widths for respectively controlling a natural gas nozzle and an alcohol fuel nozzle.
Preferably, the actuator further comprises a spark plug arranged on an engine cylinder, and the spark plug is connected with the ECU through an ignition coil driving module.
Preferably, the device further comprises an alcohol fuel selection switch connected to the ECU.
Preferably, the Alcohol Energy Substitution Rate (AESR) is expressed as:
wherein m is alco Is the instantaneous mass flow of the alcohol fuel, h alco Lower heating value of alcohol fuel, m NG Is the instantaneous mass flow of natural gas, h NG Is the low heating value of natural gas.
Preferably, the natural gas injection amount is expressed as:
the alcohol fuel injection amount is expressed as:
wherein alpha is NG Is the stoichiometric air-fuel ratio of natural gas, alpha alco Is the stoichiometric air-fuel ratio of the alcohol fuel,
representing the current cycle intake air quantity, m alco_feedforward Feed-forward injection quantity of alcohol fuel, m NG_feedforward Is a feed forward injection of natural gas.
Preferably, the correction is a product of a correction coefficient, which is expressed by:
wherein k is s Is the output value of the PID control algorithm, f feedback For feedback of the correction factor, t represents the current cycle and t-1 represents the previous cycle.
Preferably, the alcohol fuel is selected from methanol, ethanol or n-butanol.
A method of reducing the heat load of a natural gas engine by blending alcohol comprising the steps of:
in the current cycle of the engine, according to the actual excess air factor (lambda) actual ) Energy Substitution Rate (AESR) and target excess air factor (λ) for reference target alcohols theory ) The determined natural gas injection quantity and the alcohol fuel injection quantity are respectively corrected, so that the engine can smoothly run at the target excess air coefficient (lambda) the ory) and any alcohol fuel blending ratio.
Preferably, the method for reducing the heat load of the natural gas engine by blending the alcohol specifically comprises the following steps:
1) starting the engine in a pure natural gas mode, and switching to a natural gas/alcohol dual-fuel mode after the engine is started;
2) under the condition of given engine load, according to the air inlet temperature and pressure signal after the throttle valve, the air inlet quantity of the current cycle is calculated by using a speed density method, and according to the calculated air inlet quantity and the set excessAir volume coefficient (i.e.. lambda.) theory ) Calculating the mass of the natural gas and the alcohol fuel which need to be injected in the current cycle by combining the set alcohol energy substitution rate (namely AESR) and the low heating value and the stoichiometric air-fuel ratio of the natural gas and the alcohol fuel, and obtaining the basic injection quantity of the natural gas and the alcohol fuel for feedforward control;
3) due to the aging of natural gas and alcohol fuel nozzles and the difference between the nozzles, the air sucked and the fuel injected in the current cycle do not necessarily satisfy the set excess air ratio, and the actual excess air ratio (lambda) is obtained by measuring the oxygen concentration in the exhaust gas of the previous cycle actual ) According to the actual excess air factor (lambda) actual ) With a set excess air ratio (i.e.. lambda.) theory ) The correction coefficient of the injection quantity of the natural gas and the alcohol fuel is calculated according to the deviation, the correction injection quantity of the natural gas and the alcohol fuel for feedback control is respectively calculated according to the correction coefficient and the basic injection quantity of the natural gas and the alcohol fuel, and the corresponding correction injection quantity is converted into the injection pulse width.
Preferably, the correction injection amount is a product of a correction coefficient and the corresponding basic injection amount.
The invention has the following beneficial effects:
according to the invention, through accurately controlling the excess air coefficient and the alcohol energy substitution rate, the alcohol fuel can be substituted in any proportion according to the requirement of an engine control strategy, so that the heat load of the natural gas engine can be reduced by mixing and burning the alcohol fuel (creating conditions for further improving the compression ratio of the engine and further increasing the heat efficiency of the natural gas engine), the combustion isochoric degree can be increased, the effective heat efficiency of the engine is further increased, and the hydrocarbon emission is reduced. The invention can ensure the stable working operation of the engine and broaden the selection range of alcohol fuels (such as methanol, ethanol and n-butanol).
Drawings
FIG. 1 is a schematic structural diagram of an engine control system in an embodiment of the present invention;
FIG. 2 is a flowchart of an engine control method in an embodiment of the present invention;
in the figure: the device comprises a pressure regulator 1, a mass flow meter 2, a natural gas nozzle 3, an alcohol fuel common rail 4, an ignition coil driving module 5, a pressure regulating valve 6, a natural gas filter 7, a natural gas compressed gas cylinder 8, a fuel-air mixer 9, a throttle valve 10, an intake air temperature and pressure sensor 11, an alcohol fuel nozzle 12, a spark plug 13, an air filter 14, a turbocharger 15, a post-vortex temperature sensor 16, a pre-vortex temperature sensor 17, a camshaft position sensor 18, a cooling liquid temperature sensor 19, an electronic control unit 20, a wide-range oxygen sensor 21, a machine body 22, a crankshaft position sensor 23, a storage battery 24, an alcohol fuel storage tank 25, an alcohol fuel pump 26 and an alcohol fuel selection switch 27.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. The examples are given solely for the purpose of illustration and are not intended to limit the scope of the invention.
Referring to fig. 1, the invention provides a natural gas/alcohol dual-fuel engine, which is realized by controlling the alcohol mixing of a spark-ignition natural gas engine body 22 by using an electronic control system. The electronic control system includes an electronic control unit 20 (i.e., ECU) for receiving sensor signals and performing control operations to output actuator control signals. The electronic control unit 20 is connected to a crank position sensor 23 (which may be used by the ECU to measure the engine speed), a camshaft position sensor 18 (which cooperates with the crank position sensor 23 to determine the engine operating phase and timing to determine the intake, ignition, and exhaust cycles of the engine), an intake temperature and pressure sensor 11 (which is used by the ECU to determine the engine load and perform intake air quantity calculations), and a wide-area oxygen sensor 21 (which is used by the ECU to measure the oxygen concentration in the engine exhaust gas and convert it to an excess air factor), respectively. The coolant temperature sensor 19, the pre-swirl temperature sensor 17, and the post-swirl temperature sensor 16 in fig. 1 have no effect on the injection quantity control of the present invention, and are only essential components of the engine.
The actuators controlled by the electronic control system comprise a combined natural gas nozzle 3 (adopting single-point injection of an intake manifold) for injecting natural gas, an alcohol fuel nozzle 12 (the number of the nozzles is the same as the number of cylinders of the engine, and multi-point sequential injection of the intake manifold) for injecting alcohol fuel into an intake manifold of the engine, a spark plug 13 (discharging the spark plug by using an ignition coil driving module 5 connected with an ECU) for igniting the mixture in the cylinder, and a throttle valve 10 (positioned between a fuel-air mixer 9 at the injection position of the natural gas nozzle 3 and the alcohol fuel nozzle 12) for controlling the air intake amount and the load of the engine.
The alcohol fuel supply system includes an alcohol fuel storage tank 25, an alcohol fuel pump 26 for supplying an alcohol fuel injection pressure, a pressure regulating valve 6 for regulating the alcohol fuel injection pressure and maintaining the alcohol fuel injection pressure constant, and an alcohol fuel common rail 4 for storing and accumulating pressure, in addition to the alcohol fuel nozzle 12, and the alcohol fuel in the alcohol fuel storage tank 25 is pressurized by the alcohol fuel pump 26 and then regulated by the pressure regulating valve 6, so that the pressure in the alcohol fuel common rail 4 is controlled to 0.5 MPa.
The natural gas supply system comprises the combined natural gas nozzle 3, a fuel air mixer 9 (used for promoting the natural gas sprayed by the combined natural gas nozzle 3 and the sucked air purified by an air filter 14 to form homogeneous mixed gas before passing through a throttle valve 10, the purified air can be mixed with the sprayed natural gas after being increased in density by a turbocharger 15), a natural gas compressed gas cylinder 8, a natural gas filter 7, a pressure regulator 1 used for regulating the natural gas spraying pressure and maintaining the pressure constant, and an instantaneous mass flowmeter 2 (used for calibrating the spraying amount MAP of an engine) used for measuring the natural gas consumption, wherein the high-pressure natural gas stored in the natural gas compressed gas cylinder 8 is filtered and decompressed, and then the pressure in front of the natural gas nozzle 3 is maintained at 0.8 MPa.
The invention provides an electric control system control operation method based on the natural gas/alcohol dual-fuel engine by utilizing the complementarity of natural gas and alcohol fuels (such as methanol, ethanol and n-butanol) on the combustion characteristics and the characteristic of high latent heat of vaporization of the alcohol fuels, so that the heat load of the ignition type natural gas engine can be reduced by mixing alcohol.
The control operation method can reduce the heat load of the natural gas engine through the control of the co-combustion of the methanol, can also reduce the heat load of the natural gas engine through the control of the co-combustion of the ethanol, and can also reduce the heat load of the natural gas engine through the control of the co-combustion of the n-butyl alcohol. The user is according to the difference of filling the alcohol fuel, through adjusting alcohol fuel selector switch 27 to different positions for the ECU can be through gathering the signal of alcohol fuel selector switch 27, thereby confirms the specific kind of alcohol fuel that the system used, and battery (24) provides stable power for the ECU.
Referring to fig. 2, the control operation method specifically adopts a control method combining feed-forward control and feedback control for the injection of the alcohol fuel and the natural gas of the natural gas/alcohol dual-fuel engine, so as to maintain the actual excess air coefficient (λ) under the condition that the throttle valve 10 is constant actual ) Constant and dynamically adjustable, and an Alcohol Energy Substitution Rate (AESR) constant and dynamically adjustable.
Taking the co-combustion of methanol as an example, the following detailed description will be made on the specific process of the injection control of the alcohol fuel and the natural gas (wherein the feed-forward control includes step 106, step 107, step 108, and step 113, and the feedback control includes step 116, step 117, step 118, and step 119):
step 101: the storage battery 24 supplies power to the ECU, the electric control system is electrified, and the control flow is started.
Step 102: and (5) diagnosing the sensor fault, and if the sensor is in fault, displaying fault information on a terminal (step 103), and reminding an operator to replace the sensor and eliminate the abnormality.
Step 104: if the sensor diagnosis is not abnormal, the current cycle intake air amount is calculated according to the speed density method adopted in step 106, and according to step 113, the target excess air coefficient (lambda) is used in the single natural gas mode theory ) MAP calculates an injection quantity of natural gas, converts the injection quantity to a natural gas injection pulsewidth, and starts the engine, as per step 114.
Step 105: and judging whether the engine is started successfully or not, if the engine is started unsuccessfully, re-entering the step 102, and if the engine is started unsuccessfully for 5 times, turning off the power supply of the electronic control system and checking for abnormality.
Step 106: if the engine is started successfully, the temperature and pressure of the throttle valve 10 under the current working condition are collected (by using the air inlet temperature and pressure sensor 11), and the current cycle air inlet amount (specifically, the air inlet amount is calculated by using a speed density method)
) The calculation process is shown as formula (1):
in the formula (1), the first and second groups,
air quantity/kg-s sucked for single cylinder of engine -1 ；ρ m Is the air density/kg.m in the air inlet manifold -3 ；p m Intake manifold air pressure (post throttle pressure)/kPa; r is air gas constant/J.kg -1 ·K -1 ；T m Intake manifold air temperature/K;
one cylinder volume change rate/m for engine operation 3 ·s -1 ，
Can be expressed by equation (2):
in equation (2), V is for a four-stroke engine d Displacement of one cylinder/m for an engine 3 (ii) a n is engine speed/r.min -1 。
Can be obtained according to the formulas (1) and (2)
Expressed as formula (3):
step 107: and judging whether the mode is a methanol blending mode according to the alcohol fuel selection switch 27, if so, entering a step 108, and otherwise, entering a step 109.
Step 108: feed forward injection quantity (m) of alcohol fuel (specifically methanol) based on target alcohol energy substitution rate alco_feedforward ) And feed forward injection quantity (m) of natural gas NG_feedforward ) Equation (4) must be satisfied:
in the formula (4), m alco Is the instantaneous mass flow rate/kg.h of alcohol fuel (specifically methanol) -1 ；h alco Is low calorific value (20.20 MJ.kg) of alcohol fuel (specifically methanol) -1 )；m NG Is the instantaneous mass flow rate/kg.h of natural gas -1 ；h NG Is the low heat value of natural gas (50.05 MJ.kg) -1 )。
According to a target excess air coefficient (lambda) theory ) Feed forward injection quantity (m) of alcohol fuel (specifically methanol) alco_feedforward ) And feed forward injection quantity (m) of natural gas NG_feedforward ) Equation (5) must also be satisfied:
in the formula (5), α NG Is the stoichiometric air-fuel ratio (16.92), alpha, of natural gas alco The stoichiometric air-fuel ratio of the alcohol fuel (specifically methanol) is 6.5. Target excess air factor (λ) theory ) Generally, it is 0.9 to 1.7.
According to the formula (4) and the formula (5), m can be calculated according to the formula (6) NG_feedforward ：
Similarly, m can be calculated according to the formula (7) based on the formula (4) and the formula (5) alco_feedforward ：
The AESR in formula (6) and formula (7) is the target alcohol energy substitution rate.
Step 114: the injection amount of natural gas calculated in step 113 or m calculated in step 108 NG_feedforward After being corrected, the natural gas injection pulse width needs to be converted into the natural gas injection pulse width according to the number of cylinders of the engine, the number of natural gas nozzles and the flow characteristics of the natural gas nozzles.
Step 115: m calculated in step 108 alco_feedforward After the correction, the pulse width needs to be converted into the corresponding alcohol fuel injection pulse width according to the number of cylinders of the engine, the number of nozzles of the alcohol fuel and the flow rate characteristic of the alcohol fuel nozzle.
Step 116: respectively injecting corresponding natural gas and alcohol fuel into corresponding positions of an air inlet pipe according to the natural gas injection pulse width calculated in the step 114 and the alcohol fuel injection pulse width calculated in the step 115, participating in the combustion of the cycle, and measuring the actual excess air coefficient (lambda) after the combustion actual ) The injection amount correction for the next cycle.
Step 117: actual excess air factor (lambda) from previous cycle actual ) Target excess air ratio (lambda) to the present cycle theory ) To calculate a corresponding feedback correction factor (f) feedback ) The calculation method of the feedback correction coefficient can be expressed as formula (8):
f feedback ＝1+k s (λ actual -λ theory ) (8)
in the formula (8), k s Is the output value of the classical PID control algorithm,it should be noted that the wide-area oxygen sensor 21 is not in operation (i.e., λ can be measured) until it is operational actual Front), f feedback Is set to 1.
Step 118: the feedback correction coefficient (f) calculated in step 117 feedback ) And the natural gas feedforward injection quantity (m) calculated in step 108 NG_feedforward ) Multiplying to calculate the final natural gas injection quantity (m) NG_total ) The calculation process is shown in formula (9):
m NG_total ＝f feedback ×m NG_feedforward (9)
the injection amount of natural gas calculated in step 113 is corrected in the manner of the above equation (9).
Step 119: the feedback correction coefficient (f) calculated in step 117 feedback ) And the feedforward injection quantity (m) of the alcohol fuel (specifically methanol) calculated in step 108 alco_feedforward ) Multiplying the obtained values to calculate the final injection amount (m) of the alcohol fuel (specifically, methanol) alco_total ) The calculation process is shown in equation (10).
m alco_total ＝f feedback ×m alco_feedforward (10)
Step 120: injecting final alcohol fuel (specifically methanol) with amount (m) alco_total ) And natural gas injection quantity (m) NG_total ) And converting the current pulse width into a corresponding injection pulse width to realize feedback control, and turning to the step 106 to perform the next circulation methanol co-combustion control.
When the engine is operated in the ethanol co-combustion mode, the fuel injection of ethanol and natural gas is also performed by combining the feedforward control and the feedback control, as shown in fig. 2:
step 109: and judging whether the mode is a blended ethanol mode according to the alcohol fuel selection switch 27, if so, entering a step 110, and otherwise, entering a step 111.
Step 110: referring to step 108, the energy substitution rate of the target alcohol (specifically, ethanol) and the target excess air ratio (λ) can be determined according to the target alcohol (specifically, ethanol) theory ) Calculating the feedforward injection amount of ethanol and the feedforward injection amount of natural gas, and performing subsequent feedback controlSimilar to the mode of co-firing methanol.
The difference compared with the mode of mixing and burning methanol is that the lower calorific value of ethanol is 27 MJ.kg -1 Ethanol has a stoichiometric air-fuel ratio of 9; in addition, when ethanol is used as the fuel, the injection characteristics of the fuel nozzle are also different from those of methanol.
When the engine works in the n-butanol blended mode, the fuel injection mode of the n-butanol and the natural gas also adopts a mode of combining feed-forward control and feedback control, and the method is shown in figure 2:
step 111: judging whether the mode is a mode of blending and burning the n-butanol according to the alcohol fuel selection switch 27, if so, entering a step 112, otherwise, entering a step 113.
Step 112: referring to step 108, the energy substitution rate of the target alcohol (specifically n-butanol) and the target excess air ratio (λ) can be determined according to the target alcohol (specifically n-butanol) theory ) And calculating the feedforward injection quantity of the n-butyl alcohol and the feedforward injection quantity of the natural gas, wherein the subsequent feedback control is similar to the mode of co-burning the methanol.
Compared with the methanol blended mode, the lower calorific value of the n-butyl alcohol is 33.1 MJ.kg -1 The stoichiometric air-fuel ratio of n-butanol was 11.2; in addition, when n-butanol is used as a fuel, the injection characteristics of the fuel nozzle are also different from those of methanol and ethanol.
In summary, the actual excess air factor (λ) measured with a wide-area oxygen sensor of the present invention actual ) Performing closed-loop control on the injection quantity of natural gas and alcohol fuel to ensure that the engine stably runs at a target excess air coefficient (lambda) theory ) Under the condition of any alcohol fuel blending combustion proportion, the heat load of the natural gas engine can be reduced by blending the methanol, and the heat load of the natural gas engine can be reduced by blending the ethanol or the n-butyl alcohol, so that the natural gas engine can work at a relatively high compression ratio, the combustion efficiency of natural gas is improved, the effective heat efficiency is increased, and the hydrocarbon emission is reduced.
Claims (9)
1. An apparatus for reducing the thermal load of a natural gas engine by blending alcohol, comprising: the device comprises an electric control system and an actuator, wherein the actuator comprises a natural gas nozzle (3) and an alcohol fuel nozzle (12), the electric control system comprises an ECU and sensors which are connected with the ECU and are used for respectively measuring the engine speed, the engine running phase and timing, the engine intake air temperature and pressure and the engine exhaust oxygen concentration, and the ECU respectively corrects the natural gas injection quantity and the alcohol fuel injection quantity determined by referring to an alcohol energy substitution rate and a target excess air coefficient according to an actual excess air coefficient to generate injection pulse widths used for respectively controlling the natural gas nozzle (3) and the alcohol fuel nozzle (12);
the natural gas injection quantity is expressed as:
the alcohol fuel injection amount is expressed as:
wherein alpha is NG Is the stoichiometric air-fuel ratio of natural gas, alpha alco Is the stoichiometric air-fuel ratio of alcohol fuel, h alco Is a lower heating value of alcohol fuel, h NG Is the low heating value of the natural gas,
representing the current cycle intake air quantity, m alco_feedforward Feed-forward injection quantity of alcohol fuel, m NG_feedforward For feed-forward injection of natural gas, lambda theory For target excess air coefficient, AESR is alcohol energy substitution;
V d representing the displacement of the engine cylinder, n being the engine speed, p m Is intake manifold air pressure, R is air gas constant, T m Is the intake manifold air temperature.
2. The apparatus of claim 1, wherein the means for reducing the thermal load of the natural gas engine comprises: the actuator further comprises a spark plug (13), and the spark plug (13) is connected with the ECU through an ignition coil driving module (5).
3. The apparatus of claim 1, wherein the means for reducing the thermal load of the natural gas engine comprises: the device also includes an alcohol fuel selector switch (27) connected to the ECU.
4. The apparatus of claim 1, wherein the means for reducing the thermal load of the natural gas engine comprises: the alcohol energy substitution rate is expressed as:
wherein m is alco Is the instantaneous mass flow of the alcohol fuel, h alco Lower heating value of alcohol fuel, m NG Is the instantaneous mass flow of natural gas, h NG For low heating value of natural gas, AESR is the alcohol energy substitution rate.
5. The apparatus of claim 1, wherein the means for reducing the thermal load of the natural gas engine comprises: the correction is to multiply a correction coefficient by the natural gas injection amount and the alcohol fuel injection amount, wherein the correction coefficient is expressed as:
wherein k is s Is the output value of the PID control algorithm, f feedback For feedback of correction factor, λ the ory is the target excess air factor, λ actual For actual excess airThe coefficient, t represents the current cycle and t-1 represents the previous cycle.
6. The apparatus of claim 1, wherein the means for reducing the thermal load of the natural gas engine comprises: the alcohol fuel is selected from methanol, ethanol or n-butanol.
7. A method of reducing the thermal load of a natural gas engine by blending alcohol, characterized by: the method comprises the following steps:
in the current cycle of the engine, respectively correcting the natural gas injection quantity and the alcohol fuel injection quantity determined by referring to the alcohol energy substitution rate and the target excess air coefficient according to the actual excess air coefficient, so that the engine operates under the target excess air coefficient and any alcohol fuel co-combustion proportion;
the natural gas injection quantity is expressed as:
the alcohol fuel injection amount is expressed as:
wherein alpha is NG Is the stoichiometric air-fuel ratio of natural gas, alpha alco Is the stoichiometric air-fuel ratio of alcohol fuel, h alco Is a lower heating value of alcohol fuel, h NG Is the low heating value of the natural gas,
representing the current cycle intake air quantity, m alco_feedforward Feed-forward injection quantity of alcohol fuel, m NG_feedforward For feed-forward injection of natural gas, lambda theory For the target excess air coefficient, AESR is the alcohol energy substitution rate;
V d representing the displacement of the engine cylinder, n being the engine speed, p m Is intake manifold air pressure, R is air gas constant, T m Is the intake manifold air temperature.
8. The method of reducing the heat load of a natural gas engine by blending alcohol according to claim 7, wherein: the method for reducing the heat load of the natural gas engine specifically comprises the following steps:
1) after the engine is started in a pure natural gas mode, switching to a natural gas/alcohol dual-fuel mode;
2) under the condition of given engine load, calculating the air inflow of the current cycle by using a speed density method according to an air inlet temperature and a pressure signal, and calculating the basic injection quantity of natural gas and alcohol fuel used for feedforward control in the current cycle according to the calculated air inflow, a set excess air coefficient and an alcohol energy substitution rate and by combining the low heat value and the stoichiometric air-fuel ratio of the natural gas and the alcohol fuel;
3) the method comprises the steps of measuring the oxygen concentration in the last cycle of exhaust gas to obtain an actual excess air coefficient, calculating correction coefficients of the injection quantities of natural gas and alcohol fuel according to the deviation of the actual excess air coefficient and a set excess air coefficient, calculating correction injection quantities of the natural gas and the alcohol fuel for feedback control according to the correction coefficients and basic injection quantities of the natural gas and the alcohol fuel, and converting the corresponding correction injection quantities into injection pulse widths.
9. The method of reducing the heat load of a natural gas engine by blending alcohol according to claim 8, wherein: the correction injection quantity is a product of a correction coefficient and a corresponding basic injection quantity.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN203584586U (en) * | 2013-09-30 | 2014-05-07 | 赵永胜 | Alcohols and natural gas of natural gas internal combustion engine and injection and control system for switching alcohols and natural gas |
| CN204552937U (en) * | 2015-04-25 | 2015-08-12 | 安徽中禄新能源科技开发有限公司 | A kind of high efficiency and multi-function methanol fuel interlock integral engine |
| CN105508063A (en) * | 2014-09-25 | 2016-04-20 | 陕西汽车集团有限责任公司 | Vehicle natural gas methanol mixed combustion system, engine system and vehicle |
| CN110318868A (en) * | 2019-07-12 | 2019-10-11 | 南京盖驰动力科技有限公司 | A kind of control system and its control method of methanol/natural gas flexible fuel engine |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN203584586U (en) * | 2013-09-30 | 2014-05-07 | 赵永胜 | Alcohols and natural gas of natural gas internal combustion engine and injection and control system for switching alcohols and natural gas |
| CN105508063A (en) * | 2014-09-25 | 2016-04-20 | 陕西汽车集团有限责任公司 | Vehicle natural gas methanol mixed combustion system, engine system and vehicle |
| CN204552937U (en) * | 2015-04-25 | 2015-08-12 | 安徽中禄新能源科技开发有限公司 | A kind of high efficiency and multi-function methanol fuel interlock integral engine |
| CN110318868A (en) * | 2019-07-12 | 2019-10-11 | 南京盖驰动力科技有限公司 | A kind of control system and its control method of methanol/natural gas flexible fuel engine |
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