Alcohol hydrogen engine system and control method

Abstract

The invention discloses an alcohol hydrogen engine system and a control method. The engine system comprises an engine, a methanol box, a methanol pump, a methanol heater, an NH3 reforming hydrogen production device, a hydrogen-rich gas storage tank, a urea box, a urea pump and an SCR aftertreatment system. The engine nozzle is a coaxial double-channel hydrogen and methanol nozzle, injection of two kinds of fuel can be achieved through one nozzle, and flexible control over different proportions of hydrogen and methanol can be achieved in the same combustion cycle. According to the method, the mode that the NH3 urea water solution is used for online preparation of hydrogen and liquid methanol for mixed combustion is adopted, the cold start problem of the methanol engine is solved, meanwhile, engine waste heat is effectively recycled, the fuel heat value grade is improved, and then the engine heat efficiency is improved; and the combustion speed can be effectively increased by adopting hydrogen gas to assist combustion, so that the heat efficiency of the engine is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of engine systems, and in particular to an alcohol-hydrogen engine system and a control method. Background Art

[0003] The chemical formula of methanol is CH30H, and the oxygen atoms in it can effectively improve the combustion efficiency during the combustion process of the internal combustion engine, reduce unburned hydrocarbons and other substances, and achieve cleaner emissions. However, liquid methanol fuel has the characteristics of low saturated vapor pressure, large latent heat of vaporization, and is not easy to volatilize in low temperature environments. Therefore, its application in engines has poor methanol spray atomization performance, especially in winter when the ambient temperature is low, methanol will have problems with cold start due to poor atomization effect.

[0004] The current National VI heavy-duty engine after-treatment system adopts the NH3-SCR system, which has a complete urea supply system including a urea tank, a urea pump, and a urea pipeline. Urea aqueous solution can generate H2 under the action of heat and catalysts. Hydrogen has combustion advantages such as a wide ignition limit and a fast combustion speed. Its combustion application in the engine can effectively reduce combustion losses, improve combustion efficiency, and thus improve the effective thermal efficiency of the engine. At the same time, hydrogen is a gaseous fuel, and its ignition energy is low, and there is no problem of low-temperature atomization and poor cold start performance. Therefore, if a hydrogen and methanol mixed combustion chamber can be used, the poor cold start of methanol can be effectively solved, while improving the thermal efficiency of the engine. In addition, the reforming of NH3 aqueous solution to produce hydrogen can also recover part of the exhaust gas waste heat, further improving the overall efficiency of the system. Summary of the invention

[0005] In view of the technical problems pointed out in the background technology, the purpose of the present invention is to provide an alcohol hydrogen engine system and a control method.

[0006] To achieve the purpose of the present invention, the technical solution provided by the present invention is as follows:

[0007] First aspect

[0008] The present invention provides an alcohol hydrogen engine system, comprising an engine, a methanol tank, a methanol pump, a methanol heater, an NH3 reforming hydrogen production device, a hydrogen-rich gas storage tank, a urea tank, a urea pump and an SCR post-treatment system;

[0009] Among them, the methanol tank is connected to the methanol pump, the methanol pump is connected to the engine through a pipeline, and is connected to the methanol heater through a pipeline provided with a valve V1, the exhaust pipeline of the methanol heater is connected to the NH3 reforming hydrogen production device, the exhaust pipeline of the engine is connected to the NH3 reforming hydrogen production device and the SCR post-treatment system in sequence, the urea tank is connected to the urea pump, the urea pump is connected to the NH3 reforming hydrogen production device and the SCR post-treatment system, the NH3 reforming hydrogen production device is connected to the hydrogen-rich gas storage tank through a pipeline, and the hydrogen-rich gas storage tank is connected to the engine; the engine nozzle is a gas-liquid dual-fuel nozzle.

[0010] Furthermore, the system is used to perform the following control method:

[0011] Step 1: Cold start condition, specifically as follows: ECU determines that the engine operating condition is cold start, then ECU controls to open the hydrogen-rich gas storage tank, H2 starts to be injected, the spark plug ignites, and the engine starts successfully; while the engine is starting, ECU also controls the methanol pump to start working, V1 controls to open, and methanol is started to be supplied to the methanol heater, and the methanol heater starts to work to provide exhaust gas heat to heat the NH3 reforming hydrogen production device; at this time, the NH3 reforming hydrogen production device does not have enough heat to reform NH3 to generate H2, so the alcohol-hydrogen engine uses the hydrogen in the hydrogen-rich gas storage tank, methanol is not injected, and only hydrogen is injected;

[0012] Step 2: Warm-up condition, as follows: the engine has been successfully started, and the ECU determines that the engine is in the warm-up condition according to the rotation; the NH3 reforming hydrogen production device still cannot work normally. At this time, the heat of the methanol heater exhaust gas and the heat of the engine exhaust gas simultaneously heat the NH3 reforming hydrogen production device, shortening the heating time of the NH3 reforming hydrogen production device; under this condition, the engine fuel is supplied by 90% hydrogen and 10% liquid methanol, and the hydrogen comes entirely from the hydrogen-rich gas storage tank; at this time, the alcohol-hydrogen engine nozzle also sprays liquid methanol;

[0013] Step 3: Normal operating conditions, as follows: the engine ECU determines that the engine is operating under normal operating conditions; under this condition, the methanol heater is turned off and V1 is turned off; the NH3 aqueous solution enters the NH3 reforming hydrogen production device through the urea tank and urea pump, and hydrogen is produced online under the heating of the engine exhaust waste heat; the generated hydrogen enters the hydrogen-rich gas storage tank and is stored for future use; the engine operates with different hydrogen and liquid methanol mixing ratios according to different load conditions.

[0014] Furthermore, under light load conditions, a mixture ratio of 70% hydrogen and 30% liquid methanol is adopted; under medium load conditions, a mixture ratio of 80% hydrogen and 20% liquid methanol is adopted; under heavy load conditions, a mixture ratio of 50% hydrogen and 50% liquid methanol is adopted; under acceleration conditions, in order to ensure acceleration performance, direct injection of liquid methanol is required to increase the ratio, so the mixture ratio of liquid methanol and hydrogen is 80%:20%.

[0015] Furthermore, the ECU determines the engine operating condition based on the engine speed, torque, water temperature and oil temperature.

[0016] Furthermore, the engine nozzle is a coaxial dual-channel hydrogen and methanol nozzle.

[0017] Second aspect

[0018] The present invention provides a control method for an alcohol-hydrogen engine system. The system adopts the above-mentioned alcohol-hydrogen engine system. The control method comprises the following steps:

[0019] Step 1: Cold start condition, specifically as follows: ECU determines that the engine operating condition is cold start, then ECU controls to open the hydrogen-rich gas storage tank, H2 starts to be injected, the spark plug ignites, and the engine starts successfully; while the engine is starting, ECU also controls the methanol pump to start working, V1 controls to open, and methanol is started to be supplied to the methanol heater, and the methanol heater starts to work to provide exhaust gas heat to heat the NH3 reforming hydrogen production device; at this time, the NH3 reforming hydrogen production device does not have enough heat to reform NH3 to generate H2, so the alcohol-hydrogen engine uses the hydrogen in the hydrogen-rich gas storage tank, methanol is not injected, and only hydrogen is injected;

[0020] Step 2: Warm-up condition, as follows: the engine has been successfully started, and the ECU determines that the engine is in the warm-up condition according to the rotation; the NH3 reforming hydrogen production device still cannot work normally. At this time, the heat of the methanol heater exhaust gas and the heat of the engine exhaust gas simultaneously heat the NH3 reforming hydrogen production device, shortening the heating time of the NH3 reforming hydrogen production device; under this condition, the engine fuel is supplied by 90% hydrogen and 10% liquid methanol, and the hydrogen comes entirely from the hydrogen-rich gas storage tank; at this time, the alcohol-hydrogen engine nozzle also sprays liquid methanol;

[0021] Step 3: Normal operating conditions, as follows: the engine ECU determines that the engine is operating under normal operating conditions; under this condition, the methanol heater is turned off and V1 is turned off; the NH3 aqueous solution enters the NH3 reforming hydrogen production device through the urea tank and urea pump, and hydrogen is produced online under the heating of the engine exhaust waste heat; the generated hydrogen enters the hydrogen-rich gas storage tank and is stored for future use; the engine operates with different hydrogen and liquid methanol mixing ratios according to different load conditions.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The engine nozzle of the present invention is a coaxial dual-channel hydrogen and methanol nozzle, which can realize the injection of two fuels in one nozzle, and can realize flexible control of different proportions of hydrogen and methanol in the same combustion cycle. The present invention adopts the method of online preparation of hydrogen gas and liquid methanol for mixed combustion by NH3 urea aqueous solution, which not only solves the cold start problem of methanol engine, but also effectively recovers the waste heat of engine, improves the calorific value of fuel and thus improves the thermal efficiency of engine. In addition, the use of hydrogen gas-assisted combustion can also effectively increase the combustion speed and improve the thermal efficiency of engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of the structure of an engine system provided by an embodiment of the present invention;

[0025] Figure 2 A schematic diagram of the mixing ratio of the engine under various operating conditions provided by an embodiment of the present invention;

[0026] Figure 3 A schematic diagram of the normal operating conditions of an engine provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Methanol heater: It uses methanol as fuel, ignites and burns to heat the cooling medium, and circulates in the entire engine cooling system under the action of the built-in circulating water pump of the methanol heater to achieve the purpose of heating the cooling water and quickly warming up the engine. At the same time, the waste heat of the heater's exhaust gas can heat the NH3 reforming hydrogen production device.

[0029] NH3 reforming hydrogen production device: NH3 aqueous solution enters the hydrogen production device through the urea supply system such as urea tank and urea pump. In the hydrogen production device, hydrogen is produced online under the heating of waste heat from exhaust gas.

[0030] like Figure 1 As shown, the present invention provides an alcohol hydrogen engine system, including an engine, a methanol tank, a methanol pump, a methanol heater, an NH3 reforming hydrogen production device, a hydrogen-rich gas storage tank, a urea tank, a urea pump and an SCR post-treatment system;

[0031] The methanol tank is connected to the methanol pump, which is connected to the engine through a pipeline and to the methanol heater through a pipeline provided with a valve V1. The exhaust pipeline of the methanol heater is connected to the NH3 reforming hydrogen production device, and the exhaust pipeline of the engine is connected to the NH3 reforming hydrogen production device and the SCR post-processing system in sequence. The urea tank is connected to the urea pump, which is connected to the NH3 reforming hydrogen production device and the SCR post-processing system. The NH3 reforming hydrogen production device is connected to the hydrogen-rich gas storage tank through a pipeline, and the hydrogen-rich gas storage tank is connected to the engine. The engine nozzle is a gas-liquid dual-fuel nozzle. The engine nozzle is a coaxial dual-channel hydrogen and methanol nozzle.

[0032] like Figure 2 and Figure 3 As shown, the engine can be simply divided into cold start condition, warm-up condition and normal operating condition. The normal operating condition can be divided into A1 (small load) condition, A2 (medium load) condition and A3 (large load) condition, as well as acceleration and deceleration transient condition.

[0033] The system is used to perform the following control method:

[0034] Step 1: Cold start condition: ECU determines that the engine operating condition is a cold start based on parameters such as engine speed, torque, water temperature and oil temperature. Then, ECU controls the opening of the hydrogen-rich gas storage tank, H2 starts to be injected, the spark plug ignites, and the engine starts successfully. While the engine is starting, ECU also controls the methanol pump to start working, V1 control opens, and methanol is supplied to the methanol heater. The methanol heater starts working to provide exhaust gas heat to heat the NH3 reforming hydrogen production device. However, at this time, since the NH3 reforming hydrogen production device does not have enough heat to reform NH3 to generate H2, the engine uses the hydrogen in the hydrogen-rich gas storage tank. At the same time, since the engine water temperature is also very low, liquid methanol is not easy to atomize, so methanol is not injected, and only hydrogen is injected.

[0035] Step 2: Warm-up condition: The engine has been successfully started, but the ECU determines that the engine is in warm-up condition based on parameters such as speed, torque, water temperature and oil temperature. In the warm-up condition, the engine water temperature and oil temperature are relatively low, and the exhaust gas heat is also relatively low, and the NH3 reforming hydrogen production device still cannot work normally. At this time, the exhaust gas heat of the methanol heater and the engine exhaust gas heat simultaneously heat the NH3 reforming hydrogen production device, shortening the heating time of the NH3 reforming hydrogen production device. Under this condition, the engine fuel is supplied by 90% hydrogen and 10% liquid methanol. Hydrogen comes entirely from the hydrogen-rich gas storage tank. At this time, the engine direct injection nozzle also sprays liquid methanol. Since its energy ratio is only 10%, the atomization performance of methanol can be well guaranteed.

[0036] Step 3: Normal operating conditions: The engine ECU determines whether the engine is operating under normal operating conditions based on parameters such as speed, torque, water temperature and oil temperature. Under normal operating conditions of the engine, after cold start and warm-up conditions, the temperature of the NH3 reforming hydrogen production device is suitable for reforming hydrogen production. The heat of the engine's exhaust gas can fully support NH3 reforming hydrogen production under this condition, so the methanol heater is turned off and the V1 control valve is closed under this condition. The NH3 aqueous solution is gasified in the reforming hydrogen production device to generate hydrogen. The generated hydrogen enters the hydrogen-rich gas storage tank for storage for future use. In order to ensure the normal operation and optimal operating performance of the engine, the engine is operated with different hydrogen and liquid methanol blending ratios under different operating conditions. Under the A1 small load condition, a mixture ratio of 70% hydrogen and 30% liquid methanol is used; under the A2 medium load condition, a mixture ratio of 80% hydrogen and 20% liquid methanol is used; under the A3 large load condition, a mixture ratio of 50% hydrogen and 50% liquid methanol is used; under the acceleration condition, in order to ensure the acceleration performance, direct injection of liquid methanol is required to increase the ratio, so the mixture ratio of liquid methanol and hydrogen is 80%:20%.

[0037] The present invention constructs a hydrogen and liquid methanol mixed combustion system, which can realize online production of hydrogen, recover waste heat, and improve the calorific value of fuel. Moreover, within the entire engine operating range, the ratio of hydrogen and liquid methanol can be flexibly controlled according to the engine operating characteristics, so as to optimize the engine performance.

[0038] In addition, the present invention provides a control method for an alcohol-hydrogen engine system, wherein the system adopts the above-mentioned alcohol-hydrogen engine system, and the control method comprises the following steps:

[0039] Step 1: Cold start condition, specifically as follows: ECU determines that the engine operating condition is cold start, then ECU controls to open the hydrogen-rich gas storage tank, H2 starts to be injected, the spark plug ignites, and the engine starts successfully; while the engine is starting, ECU also controls the methanol pump to start working, V1 controls to open, and methanol is started to be supplied to the methanol heater, and the methanol heater starts to work to provide exhaust gas heat to heat the NH3 reforming hydrogen production device; at this time, the NH3 reforming hydrogen production device does not have enough heat to reform NH3 to generate H2, so the alcohol-hydrogen engine uses the hydrogen in the hydrogen-rich gas storage tank, methanol is not injected, and only hydrogen is injected;

[0040] Step 2: Warm-up condition, as follows: the engine has been successfully started, and the ECU determines that the engine is in the warm-up condition according to the rotation; the NH3 reforming hydrogen production device still cannot work normally. At this time, the heat of the methanol heater exhaust gas and the heat of the engine exhaust gas simultaneously heat the NH3 reforming hydrogen production device, shortening the heating time of the NH3 reforming hydrogen production device; under this condition, the engine fuel is supplied by 90% hydrogen and 10% liquid methanol, and the hydrogen comes entirely from the hydrogen-rich gas storage tank; at this time, the alcohol-hydrogen engine nozzle also sprays liquid methanol;

[0041] Step 3: Normal operating conditions, as follows: the engine ECU determines that the engine is operating under normal operating conditions; under this condition, the methanol heater is turned off and V1 is turned off; the NH3 aqueous solution enters the NH3 reforming hydrogen production device through the urea tank and urea pump, and hydrogen is produced online under the heating of the engine exhaust waste heat; the generated hydrogen enters the hydrogen-rich gas storage tank and is stored for future use; the engine operates with different hydrogen and liquid methanol mixing ratios according to different load conditions.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate and explain the present invention, and are not intended to limit the present invention to the scope of the described embodiments. In addition, those skilled in the art can understand that the present invention is not limited to the above embodiments, and more variations and modifications can be made according to the teachings of the present invention, and these variations and modifications all fall within the scope of the protection claimed by the present invention.

Claims

1. An alcohol-hydrogen engine system, characterized in that: It includes engine, methanol tank, methanol pump, methanol heater, NH3 reforming hydrogen production device, hydrogen-rich gas storage tank, urea tank, urea pump and SCR post-treatment system; Among them, the methanol tank is connected to the methanol pump, the methanol pump is connected to the engine through a pipeline, and is connected to the methanol heater through a pipeline provided with a valve V1, the exhaust pipeline of the methanol heater is connected to the NH3 reforming hydrogen production device, the exhaust pipeline of the engine is connected to the NH3 reforming hydrogen production device and the SCR post-treatment system in sequence, the urea tank is connected to the urea pump, the urea pump is connected to the NH3 reforming hydrogen production device and the SCR post-treatment system, the NH3 reforming hydrogen production device is connected to the hydrogen-rich gas storage tank through a pipeline, and the hydrogen-rich gas storage tank is connected to the engine; the engine nozzle is a gas-liquid dual-fuel nozzle.

2. The alcohol-hydrogen engine system according to claim 1, characterized in that: The system is used to perform the following control method: Step 1: Cold start condition, specifically as follows: ECU determines that the engine operating condition is cold start, then ECU controls to open the hydrogen-rich gas storage tank, H2 starts to be injected, the spark plug ignites, and the engine starts successfully; while the engine is starting, ECU also controls the methanol pump to start working, V1 controls to open, and methanol is started to be supplied to the methanol heater, and the methanol heater starts to work to provide exhaust gas heat to heat the NH3 reforming hydrogen production device; at this time, the NH3 reforming hydrogen production device does not have enough heat to reform NH3 to generate H2, so the alcohol-hydrogen engine uses the hydrogen in the hydrogen-rich gas storage tank, methanol is not injected, and only hydrogen is injected; Step 2: Warm-up condition, as follows: the engine has been successfully started, and the ECU determines that the engine is in the warm-up condition according to the rotation; the NH3 reforming hydrogen production device still cannot work normally. At this time, the heat of the methanol heater exhaust gas and the heat of the engine exhaust gas simultaneously heat the NH3 reforming hydrogen production device, shortening the heating time of the NH3 reforming hydrogen production device; under this condition, the engine fuel is supplied by 90% hydrogen and 10% liquid methanol, and the hydrogen comes entirely from the hydrogen-rich gas storage tank; at this time, the alcohol-hydrogen engine nozzle also sprays liquid methanol; Step 3: Normal operating conditions, as follows: the engine ECU determines that the engine is operating under normal operating conditions; under this condition, the methanol heater is turned off and V1 is turned off; the NH3 aqueous solution enters the NH3 reforming hydrogen production device through the urea tank and urea pump, and hydrogen is produced online under the heating of the engine exhaust waste heat; the generated hydrogen enters the hydrogen-rich gas storage tank and is stored for future use; the engine operates with different hydrogen and liquid methanol mixing ratios according to different load conditions.

3. The alcohol-hydrogen engine system according to claim 2, characterized in that: Under light load conditions, a mixture ratio of 70% hydrogen and 30% liquid methanol is used; under medium load conditions, a mixture ratio of 80% hydrogen and 20% liquid methanol is used; under heavy load conditions, a mixture ratio of 50% hydrogen and 50% liquid methanol is used; under acceleration conditions, in order to ensure acceleration performance, direct injection of liquid methanol is required to increase the ratio, so the mixture ratio of liquid methanol and hydrogen is 80%:20%.

4. The alcohol-hydrogen engine system according to claim 2, characterized in that: The ECU determines the engine operating conditions based on the engine speed, torque, water temperature and oil temperature.

5. The alcohol-hydrogen engine system according to claim 3, characterized in that: The engine nozzle is a coaxial dual-channel hydrogen and methanol nozzle.

6. A control method for an alcohol-hydrogen engine system, characterized in that: The system adopts the alcohol-hydrogen engine system according to claim 1, and the control method comprises the following steps: Step 1: Cold start condition, specifically as follows: ECU determines that the engine operating condition is cold start, then ECU controls to open the hydrogen-rich gas storage tank, H2 starts to be injected, the spark plug ignites, and the engine starts successfully; while the engine is starting, ECU also controls the methanol pump to start working, V1 controls to open, and methanol is started to be supplied to the methanol heater, and the methanol heater starts to work to provide exhaust gas heat to heat the NH3 reforming hydrogen production device; at this time, the NH3 reforming hydrogen production device does not have enough heat to reform NH3 to generate H2, so the alcohol-hydrogen engine uses the hydrogen in the hydrogen-rich gas storage tank, methanol is not injected, and only hydrogen is injected; Step 2: Warm-up condition, as follows: the engine has been successfully started, and the ECU determines that the engine is in the warm-up condition according to the rotation; the NH3 reforming hydrogen production device still cannot work normally. At this time, the heat of the methanol heater exhaust gas and the heat of the engine exhaust gas simultaneously heat the NH3 reforming hydrogen production device, shortening the heating time of the NH3 reforming hydrogen production device; under this condition, the engine fuel is supplied by 90% hydrogen and 10% liquid methanol, and the hydrogen comes entirely from the hydrogen-rich gas storage tank; at this time, the alcohol-hydrogen engine nozzle also sprays liquid methanol; Step 3: Normal operating conditions, as follows: the engine ECU determines that the engine is operating under normal operating conditions; under this condition, the methanol heater is turned off and V1 is turned off; the NH3 aqueous solution enters the NH3 reforming hydrogen production device through the urea tank and urea pump, and hydrogen is produced online under the heating of the engine exhaust waste heat; the generated hydrogen enters the hydrogen-rich gas storage tank and is stored for future use; the engine operates with different hydrogen and liquid methanol mixing ratios according to different load conditions.

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