Method for improving performance of heavy diesel H2 dual-fuel engine through engine system optimization

Abstract

A hydrogen-diesel dual fuel engine (100) includes an engine block (102) having a cylinder (104) equipped with at least two hydrogen fuel injectors (118) and a piston. An air treatment system of an engine (100) includes an intake manifold (114), an intake pipe (107), an exhaust pipe (122), a variable geometry turbocharger (108), and an exhaust gas recirculation system (126) configured to recirculate exhaust gas from the exhaust pipe (122) to the intake manifold (114). A two-stage camshaft of an engine (100) is configured with an air handling system for exhaust gas reintake and delayed intake valve closing, and a port fuel injector system (116) provides hydrogen to at least two hydrogen fuel injectors (118). The engine (100) further includes a diesel injector (305), a common rail fuel injection system (120), a plurality of sensors (150), and a controller (170) for controlling operation of the hydrogen-diesel dual fuel engine (100).

Description

Background Technology

[0001] Diesel engines are widely used in power generation and transportation. In recent years, there have been attempts to reduce diesel engine emissions, particularly by introducing hydrogen as an adjunct fuel. Theoretically, hydrogen is a promising candidate to replace some diesel fuels due to its carbon-free chemical structure. Furthermore, in many cases, hydrogen can be directly supplied to existing internal combustion (IC) engine architectures.

[0002] However, hydrogen-diesel engines are associated with many problems. In particular, current hydrogen injection strategies do not allow for cylinder-based fuel control and do not perform well in transient operation. Furthermore, combustion in hydrogen-diesel engines is actually slower than that of diesel engines with mixed control, leading to reduced engine efficiency and increased combustion losses. Therefore, current hydrogen-diesel engines exhibit reduced fuel efficiency and CO2 emission reduction potential, and operate only within limited limits. Summary of the Invention

[0003] This overview is provided to introduce some options of ideas, which will be further described in the detailed description below. This overview is not intended to identify key or essential features of the claimed subject matter, nor is it intended to serve as an aid in limiting the scope of the claimed subject matter.

[0004] The embodiments disclosed herein generally relate to a hydrogen-diesel dual-fuel engine. The hydrogen-diesel dual-fuel engine includes an engine block. The engine block includes a cylinder and a piston, wherein the cylinder is equipped with at least two hydrogen fuel injectors, wherein the piston is surrounded by the cylinder, and wherein the piston includes a piston crown. The hydrogen-diesel dual-fuel engine further includes an air treatment system. The air treatment system includes an intake manifold, an intake pipe, and an exhaust pipe, wherein the intake pipe receives air through an intake port and delivers air to the intake manifold, and wherein the exhaust pipe receives exhaust gas and discharges at least a portion of the exhaust gas. The air treatment system further includes a variable geometry turbocharger coupled to the intake pipe and the exhaust pipe, and an exhaust gas recirculation system configured to recirculate exhaust gas from the exhaust pipe back to the intake manifold. The hydrogen-diesel dual-fuel engine further includes a two-step camshaft configured with an air treatment system for exhaust gas re-intake and delayed intake valve closing; and a port fuel injector system directly integrated with the intake manifold, which supplies hydrogen to at least two hydrogen fuel injectors. The hydrogen-diesel dual-fuel engine further includes diesel injectors configured to inject diesel fuel into cylinders, a common rail fuel injection system configured to supply diesel fuel to the diesel injectors, multiple sensors, and a controller. The multiple sensors include a temperature sensor and a tachometer. The controller is configured to receive engine data from the multiple sensors and is configured to control the operation of the hydrogen-diesel dual-fuel engine.

[0005] The embodiments disclosed herein generally relate to a method for operating a hydrogen-diesel dual-fuel engine under warm conditions. The method includes determining the operating load of the hydrogen-diesel dual-fuel engine, determining a plurality of hydrogen-diesel dual-fuel engine parameters based on the operating load, and adjusting the plurality of hydrogen-diesel dual-fuel engine parameters. The plurality of hydrogen-diesel dual-fuel engine parameters include hydrogen energy parameters, equivalence ratio parameters, exhaust gas recirculation parameters, a first diesel injection event timing parameter, a second diesel injection event timing parameter, a first diesel injection quantity parameter, exhaust gas re-inhalation parameters, and a delayed intake valve closing parameter.

[0006] The embodiments disclosed herein generally relate to a method for operating a hydrogen-diesel dual-fuel engine. The method includes determining an ambient temperature, wherein the ambient temperature is the temperature of the environment surrounding the hydrogen-diesel dual-fuel engine; determining a coolant temperature, wherein the coolant temperature is the temperature of the coolant in the hydrogen-diesel dual-fuel engine; and determining an oil temperature, wherein the oil temperature is the temperature of the oil in the hydrogen-diesel dual-fuel engine. The method further includes receiving a target temperature, and determining the state of the hydrogen-diesel dual-fuel engine based on the ambient temperature, coolant temperature, oil temperature, and target temperature. The method further includes selecting an operating method based at least on the state of the hydrogen-diesel dual-fuel engine.

[0007] Other aspects and advantages of the claimed subject matter will become apparent from the following description and the appended claims. Attached Figure Description

[0008] Figure 1A A hydrogen-diesel dual-fuel engine according to one or more embodiments is described.

[0009] Figure 1B A block diagram of a hydrogen-diesel dual-fuel engine, including multiple sensors that are in electrical communication with the controller, is depicted.

[0010] Figure 2A Exhaust gas re-inhalation is described according to one or more embodiments.

[0011] Figure 2B An intake strategy according to one or more embodiments is described.

[0012] Figure 3A A piston top according to one or more embodiments is depicted.

[0013] Figure 3B A cross-sectional view of the piston top according to one or more embodiments is depicted.

[0014] Figure 4A Fuel injection strategies under low operating loads are described according to one or more embodiments.

[0015] Figure 4B Fuel injection strategies under moderate operating loads are described according to one or more embodiments.

[0016] Figure 4C Fuel injection strategies under high operating loads are described according to one or more embodiments.

[0017] Figure 5A A first diesel fuel injection event according to one or more embodiments is described.

[0018] Figure 5BA second diesel fuel injection event according to one or more embodiments is described.

[0019] Figure 6A The apparent heat release rate at low to medium operating loads is described according to one or more embodiments.

[0020] Figure 6B Apparent heat release rates at medium to high operating loads are described according to one or more embodiments.

[0021] Figure 7 The settings of an air handling system according to one or more embodiments in various regions (regimes, or states) are described.

[0022] Figures 8A to 8I Each depicts a graph showing the values ​​or settings of parameters relating to the operating load, according to one or more embodiments.

[0023] Figure 9 A flowchart according to one or more embodiments is depicted.

[0024] Figure 10 A flowchart according to one or more embodiments is depicted. Detailed Implementation

[0025] In the following detailed description of embodiments of this disclosure, numerous specific details are set forth in order to provide a more thorough understanding of the disclosure. However, it will be apparent to those skilled in the art that the disclosure may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description.

[0026] Throughout the application, ordinal numbers (e.g., first, second, third, etc.) may be used as adjectives for elements (i.e., any noun in the application). The use of ordinal numbers does not imply or create any particular ordering of elements, nor does it limit any element to being a single element, unless explicitly stated otherwise, such as the use of terms like "before," "after," "single," and other such terms. Rather, ordinal numbers are used to distinguish elements. As an example, the first element is different from the second element, and the first element may contain more than one element and be ordered after (or before) the second element.

[0027] It should be understood that, unless the context clearly specifies otherwise, the singular forms “a,” “an,” and “the” include plural indicators. Thus, for example, a reference to “acoustic signal” includes a reference to one or more such acoustic signals.

[0028] Terms such as “approximately” or “substantially” mean that the characteristic, parameter, or value does not need to be precisely achieved, but deviations or variations (including, for example, tolerances, measurement errors, measurement accuracy limitations, and other factors known to those skilled in the art) may occur in amounts that do not preclude the effect that the characteristic is intended to provide.

[0029] It should be understood that one or more steps shown in the flowchart may be omitted, repeated, and / or performed in a different order than that shown. Therefore, the scope of this document should not be construed as limited to the specific arrangement of the steps shown in the flowchart.

[0030] Although multiple dependent claims are not introduced, it will be apparent to a person skilled in the art that the subject matter of the dependent claims of one or more embodiments can be combined with other dependent claims.

[0031] In the following description of Figures 1 through 10, in the various embodiments disclosed herein, any component described with respect to the figures may be equivalent to one or more components with similar names described with respect to any other figure. For the sake of brevity, descriptions of these components will not be repeated with respect to each figure. Thus, each embodiment of a component in each figure is incorporated by reference and is assumed to optionally exist in each other figure with one or more components with similar names. Furthermore, any description of a component in the figures according to the various embodiments disclosed herein should be interpreted as an optional embodiment that may be appended to, combined with, or replaced by embodiments describing corresponding components with similar names in any other figure.

[0032] Diesel engines are widely used in power generation and transportation. Generally, diesel engines are highly efficient in energy extraction, but they typically have relatively high NO₂ levels. x Outputs include nitrogen oxides and soot (or dust) emissions. To reduce pollutants while operating diesel engines, after-treatment systems such as diesel particulate filters (DPF) and lean NOx filters have been implemented. x Recent advancements have been made in fuel traps (LNTs). However, these systems are typically expensive and can reduce engine fuel efficiency by increasing fuel consumption. Therefore, there is a need to develop engine-side technologies, such as in-cylinder combustion strategies and engine operating methods, to improve engine efficiency while reducing unwanted and harmful combustion products.

[0033] The complexity of combustion-based engines (such as diesel engines) should not be underestimated. Under equilibrium conditions, understanding the energy released during combustion, the temperature and type of products, and the power output of the thermodynamic device is a relatively simple process. This involves comparing the enthalpies of formation of reactants and products and minimizing the Gibbs free energy (i.e., maximizing entropy). However, partly due to the short residence time of combustion in the engine, equilibrium-based techniques cannot accurately predict engine output and performance. In contrast, understanding combustion in an engine requires consideration of factors such as reactant distribution, mass diffusion, chemical kinetics, and ignition timing. The combustion process in an engine is coupled at least with fluid dynamics (e.g., turbulence) and the local and global temperatures of the combustion chamber (cylinder). In fact, thermodynamic properties such as specific heat and reaction rates are strong functions of temperature, further complicating engine analysis.

[0034] Due to the complex interaction between the combustion process and the environment in a combustion engine, there is a complex space of trade-offs between desired engine characteristics. As mentioned, desired diesel engine characteristics include, but are not limited to, improved engine efficiency and reduction of harmful exhaust products and soot. For example, generally, engine efficiency, or the amount of energy that can be converted into useful mechanical work relative to the amount of available energy, increases with increasing temperature of the combustion products. However, higher combustion chamber temperatures produce higher concentrations of harmful substances, such as NO in exhaust products. x .

[0035] Due to its carbon-free chemical structure, hydrogen (H2) is gaining increasing attention in commercial transportation for its role in reducing carbon dioxide (CO2). Compared to hydrogen fuel cells, hydrogen-fueled internal combustion engines (H2-ICE) are cheaper and less complex because they do not require precious metals and can utilize existing internal combustion (IC) engine architectures and components. Furthermore, IC engines do not require high-purity hydrogen.

[0036] Furthermore, while hydrogen boasts a high flame velocity and low minimum ignition energy, it requires high pressure and temperature for auto-ignition. The research octane number (RON) for hydrogen is greater than 130. Therefore, for use as fuel in an IC engine, hydrogen needs to be combined with a robust ignition source for compression ignition operation.

[0037] Therefore, with the established goal of improving diesel engine performance while reducing emissions, dual-fuel engines using hydrogen and diesel have been proposed. This is because, intuitively, at least from a balance perspective, CO2 emissions would decrease as more hydrogen is introduced into the engine (replacing diesel). However, in reality, hydrogen-diesel dual-fuel engines have been found to be problematic. For example, at low loads, dual-fuel operation leads to high combustion losses and hydrogen leakage into the exhaust due to hydrogen's low auto-ignition tendency. On the other hand, for high-load operation, hydrogen energy input is limited due to concerns about pre-ignition, excessively high pressure rise rate, and knock. These problems have severely limited the operating range of the proposed hydrogen-diesel dual-fuel engines.

[0038] Furthermore, hydrogen-diesel dual-fuel engines have primarily achieved this by introducing hydrogen into existing diesel engines through upstream fumigation. However, upstream fumigation does not allow for precise cylinder-based fuel control (i.e., in-cylinder combustion strategies) and transient operation. Therefore, due to a lack of customized combustion and air treatment development, the fuel efficiency of hydrogen-diesel combustion is generally lower than that of blend-controlled diesel combustion. The reduced efficiency is mainly attributed to slower combustion and higher combustion losses. Consequently, current hydrogen-diesel dual-fuel engines exhibit reduced fuel efficiency and CO2 emission reduction potential, and operate only within a limited range.

[0039] In one aspect, the embodiments disclosed herein relate to a hydrogen-diesel dual-fuel engine system and a method of operation that overcomes the aforementioned problems. The hydrogen-diesel dual-fuel engine system and method of operation disclosed herein maximize engine efficiency across a full range of operating conditions (i.e., from cold startup to heavy load conditions) while reducing emissions and NOx. x The level is maintained below the current technology threshold. This is achieved in part through a customized fuel injection strategy that is compatible with the conventional piston crown geometry, as well as a load-related air handling strategy.

[0040] According to one or more embodiments, Figure 1A An overview of the hydrogen-diesel dual-fuel engine (100) is provided. It should be noted that... Figure 1A Not all components of the hydrogen-diesel dual-fuel engine (100) are depicted. However, those skilled in the art will recognize that the depiction of selected components and the associated descriptions are sufficient to provide the necessary context and distinguish unique features. Therefore, Figure 1A The fact that not all components of the hydrogen-diesel dual-fuel engine (100) are depicted in this disclosure does not constitute a limitation of this disclosure.

[0041] The hydrogen-diesel dual-fuel engine (100) has a geometric compression ratio (CR) of 16 or higher. The hydrogen-diesel dual-fuel engine (100) consists of an engine block (102) that houses one or more cylinders (104) and pistons. Figure 1A The hydrogen-diesel dual-fuel engine (100) depicted has six cylinders (104). To prevent... Figure 1A The process is haphazard; not every cylinder (104) is labeled. Air is received by the hydrogen-diesel dual-fuel engine (100) through the intake port (106) and travels to the engine block (102) via the intake manifold (107). In one or more embodiments, the intake manifold (107) is coupled to a single-stage variable geometry turbocharger (VGT) (108) for compressing the air received from the intake port (106) before it travels to the engine block (102). The VGT (108) has variable nozzles incorporated into the turbine. Before traveling to the engine block (102), the air travels through the intake manifold (107) through the boost air cooler (110) and the idle air control valve (112) and is received by the intake manifold (114). Typically, the VGT (108) increases the temperature of the incoming air. If left uncontrolled, the temperature of the reactants can become excessively high. Excessive reactant temperature may lead to reduced charge density and increased combustion temperature, which could affect torque, power, and emissions. A booster air cooler (110) cools the intake air before it enters the cylinder (104). An idle air control valve (112) regulates the airflow to the engine to ensure smooth idling.

[0042] Hydrogen is introduced into the hydrogen-diesel dual-fuel engine (100) via a multi-point port fuel injector system (116) directly integrated into the intake manifold (114). The port fuel injector system (116) consists of hydrogen fuel injectors (118). Again, to prevent... Figure 1A Not all hydrogen fuel injectors (118) are labeled. According to one or more embodiments, there are two hydrogen fuel injectors (118) per cylinder (104), and the hydrogen fuel injectors operate at a pressure difference of 5 to 7 bar across the injectors. Thus, the intake manifold (114) and port fuel injector system (116) can provide a precisely controlled mixture of hydrogen and air to each cylinder (104). The amount of hydrogen injected into each cylinder (104) can vary depending on the operating load and conditions of the hydrogen-diesel dual-fuel engine (100).

[0043] Diesel fuel is injected directly into the cylinder (104) of the hydrogen-diesel dual-fuel engine (100) via a high-pressure common rail fuel injection system (120). Typically, the diesel fuel is pressurized in the common rail fuel injection system (120) to a pressure greater than or equal to 2200 bar.

[0044] After combustion, exhaust products exit the hydrogen-diesel dual-fuel engine (100) via an exhaust pipe (122). The exhaust pipe (122) is coupled to a VGT (108). Exhaust products may be discharged into the environment or other external equipment via an exhaust outlet (124) after passing through an exhaust back pressure valve (125). The exhaust back pressure valve (125) is a variable position valve that typically controls the exhaust back pressure during cold ambient temperatures. The exhaust pipe (122) is also connected to a high-pressure exhaust gas recirculation system (126). The exhaust gas recirculation system (126) allows exhaust gas to be recirculated back to the intake manifold (114), where it can be mixed with the intake air to the hydrogen-diesel dual-fuel engine (100). The exhaust gas recirculation system (126) includes an exhaust gas recirculation valve (128) and an exhaust gas recirculation cooler (130). The exhaust gas recirculation cooler (130) provides similar functionality to the boost air cooler (110). In short, the exhaust gas recirculation cooler (130) cools the exhaust gas recirculated back to the cylinder (104). Typically, the exhaust gas recirculation cooler (130) uses engine coolant (not shown) to cool the recirculated exhaust gas, reducing its volume and increasing its density before it combines with the intake air to lower the combustion temperature and subsequently reduce NO₂. x form.

[0045] The intake manifold (107), turbocharged air cooler (110), idle air control valve (112), VGT (108), exhaust manifold (122), exhaust gas recirculation system (126), and intake manifold (114) together constitute the air handling system of the hydrogen-diesel dual-fuel engine (100). The VGT (108) and exhaust gas recirculation system (126) are designed to remove NO with low pumping losses. x The output is maintained below 1 to 2 g / kWh. Specifically, the VGT (108) housing and impeller are customized together with low-resistance piping used in the exhaust gas recirculation system (126) to deliver the equivalence ratio and exhaust gas volume specified by the method for operating the hydrogen-diesel dual-fuel engine (100), which will be detailed later in this disclosure. As will be shown, according to one or more embodiments, as the operating load of the hydrogen-diesel dual-fuel engine (100) increases, the variable blades in the VGT (108) gradually close to build sufficient boost, while the exhaust back pressure valve (125) begins to open and then gradually closes. Combined with existing emission aftertreatment equipment, the hydrogen-diesel dual-fuel engine (100) is expected to meet future ultra-low NO standards of 0.027 g / kWh. x Threshold.

[0046] like Figure 1BAs depicted herein, in one or more embodiments, the hydrogen-diesel dual-fuel engine (100) is coupled to a controller (170) (i.e., the hydrogen-diesel dual-fuel engine (100) and the controller (170) are in electrical communication). The controller (170) is configured to receive measurements from a plurality of sensors (150) disposed on the hydrogen-diesel dual-fuel engine (100) and is configured to control the behavior of various components of the hydrogen-diesel dual-fuel engine (100). The plurality of sensors are capable of reading engine data (160) (one or more measurements describing the state of the engine), which can be used to determine the operating load of the hydrogen-diesel dual-fuel engine (100). In one or more embodiments, the plurality of sensors (150) includes one or more temperature sensors disposed on or throughout the engine, and a tachometer. For example, the temperature sensors may be configured to measure the temperature of various fluids in the engine, such as oil and coolant. The controller (170) can provide control signals (180) (e.g., commands, electrical communications, etc.) to the components of the hydrogen-diesel dual-fuel engine (100) to alter their behavior according to a determined operating load of the hydrogen-diesel dual-fuel engine (100). That is, there are various controllable settings, parameters, and / or quantities associated with the hydrogen-diesel dual-fuel engine (100). For example, according to one or more embodiments, the relative amounts of hydrogen and diesel used in the hydrogen-diesel dual-fuel engine (100), fuel injection timing, the amount of exhaust gas recirculation used, and fuel injection pressure are adjusted by the controller (170) according to the determined operating load. The use of the controller (170) to alter the controllable settings, parameters, and / or quantities associated with the hydrogen-diesel dual-fuel engine (100) according to the determined operating load of the hydrogen-diesel dual-fuel engine (100) will be discussed in more detail later in this disclosure.

[0047] The air handling system is further configured to work with a two-stage camshaft (not shown) that is capable of exhaust gas re-intake under low load and delayed intake valve closing (LIVC) under high load. Figure 2A and 2B The exhaust and intake rates under low and high load conditions are described respectively. Figure 2A Standard exhaust curves (202) and standard intake curves (204) are depicted, representing normal exhaust and intake modes without exhaust gas re-intake or LIVC. However, under low loads, and as... Figure 2A As shown, the secondary exhaust curve (206) indicates that some exhaust gas from the hydrogen-diesel dual-fuel engine (100) is re-inhaled and mixed with the intake air during intake. Similarly, the exhaust and intake rates under high load are depicted... Figure 2AStandard exhaust curves (202) and standard intake curves (202) are shown; however, the standard intake curve (202) is shown for illustrative purposes only. In practice, under high loads, the hydrogen-diesel dual-fuel engine (100) engages two-stage camshafts to initiate the LIVC. The intake rate using the LIVC is... Figure 2B The figure is shown by the LIVC curve (208).

[0048] The cylinder and piston top of the hydrogen-diesel dual-fuel engine (100) are designed to harmonize with the thermal environment of the cylinder (104) and the multi-stage dual-fuel injection strategy to customize fuel reactivity. According to one or more embodiments, Figure 3A and 3B The geometry of the piston crown (302) and other components near the cylinder (104) are depicted. Specifically, Figure 3A and 3B The piston crown (302) is depicted as the piston (not shown) approaches top dead center (0° CA) between the compression and expansion strokes. As seen in these figures, each cylinder (104) can receive a spray of diesel fuel from a diesel injector (305). The diesel injector (305) consists of nozzles for producing a spray pattern. In one or more embodiments, the number of nozzles in the diesel injector is greater than or equal to 12. Each cylinder (104) is also equipped with a spark igniter (306). The spark igniter (306) is capable of igniting hydrogen. As explained in more detail later in this disclosure, under cold start conditions, the hydrogen-diesel dual-fuel engine (100) operates with a substantially stoichiometric mixture of hydrogen and air (i.e., without diesel fuel). Therefore, a spark igniter (306) is provided to ignite the stoichiometric mixture of hydrogen and air.

[0049] Figure 3B A cross-sectional view of the piston top (302) is depicted. (See also...) Figure 3B As seen, the piston crown (302) has a piston cup (308) recessed into the piston crown (302). The piston cup (308) effectively forms the combustion chamber as the piston approaches the total combustion current (TDC) between the compression and expansion strokes. The design and shape of the piston cup (308) directly affect the mixing and stratification of fuel (hydrogen and diesel) and air. In one or more embodiments, the piston cup (308) is defined by a conical center (310), a substantially flat periphery (312), and a cup wall (314). The cup wall (314) and the conical center (310) form and enclose a substantially annular volume. The cup wall (314) has a curved profile with a convex radius (315). The convex radius (315) can be used as a reference to further divide the annular description into a peripheral region (316) and a central region (318). Figure 3BThe arbitrary pattern on the left-hand side indicates the outer region (316) and the central region (318); however, it is emphasized that these regions are annular and extend at an angle throughout the piston cup (308). The geometry of the piston cup (308) (e.g., a flat periphery (312), a conical center (310), and a cup wall (314) with a convex radius (315)) and the large number of nozzles (≥ 12) on the diesel injector (305) result in a low squash and zero swirl ratio in the combustion chamber.

[0050] Figures 4A to 4C A multi-stage dual-fuel injection strategy for a hydrogen-diesel dual-fuel engine (100) is described. Typically, with the port fuel injector (116) directly integrated into the intake manifold (114), hydrogen is injected into the air as air is introduced into the cylinder (104) during the intake stroke. Diesel fuel is subsequently injected into the cylinder (104) in one or two stages. As will be shown, diesel fuel is injected when the piston is near the TDC between the compression and expansion strokes. The relative amounts of hydrogen and diesel fuel introduced into the cylinder (104) depend on the operating load of the hydrogen-diesel dual-fuel engine (100). Furthermore, where applicable, the timing and relative amount of diesel fuel injected during the first and second stages depend on the operating load of the hydrogen-diesel dual-fuel engine (100). Figure 4A , 4B 4C and 4C respectively depict the rates of hydrogen and diesel injection relative to the piston crank angle (CA) under low, medium, and high loads. Generally speaking, Figures 4A to 4C The hydrogen injection event (402), the first diesel injection event (404), and the second diesel injection event (406) are depicted. The positions of the injection events (402, 404, 406) on the horizontal axis representing the crankshaft angle of the piston indicate the timing of the hydrogen and diesel injections. The width of the injection events (402, 404, 406) shows the relative amounts of hydrogen and diesel introduced into the cylinder (104) of the hydrogen-diesel dual-fuel engine (100).

[0051] As in Figure 4AAs seen in the diagram, when the hydrogen-diesel dual-fuel engine (100) is under low operating load, hydrogen is introduced into the cylinder (104) early in the intake stroke. The first diesel injection event (404) occurs between -40° and -30° aTDC (after °TDC) (during the compression stroke). The first diesel injection event (404) is followed by a pause as the piston crown (302) approaches TDC. Additional diesel fuel is injected into the cylinder (104) during the second diesel injection event (406), which terminates just before the piston crown (302) reaches TDC. Under low load, more diesel is injected into the cylinder (104) during the first diesel injection event (404) than during the second diesel injection event (406), such as... Figure 4A The relative widths of the first diesel injection event (404) and the second diesel injection event (406) are shown.

[0052] As the operating load on the hydrogen-diesel dual-fuel engine (100) increases, the amount of diesel fuel injected into the cylinder (104) during the first diesel injection event (404) gradually decreases relative to the amount of diesel fuel injected during the second diesel injection event (406). This is depicted in Figure 4B middle, Figure 4B The hydrogen and diesel fuel injection strategy of a hydrogen-diesel dual-fuel engine (100) under medium load is illustrated. Both the first diesel injection event (404) and the second diesel injection event (406) begin before the TDC (Total Discharge Flow). However, because more diesel is injected during the second diesel injection event (406) under medium load, diesel injection continues into the expansion stroke. Furthermore, as... Figure 4B As shown, a relatively small amount of hydrogen is supplied to the hydrogen-diesel dual-fuel engine (100).

[0053] Under high operating loads, the loading of cylinder (104) is expected to increase significantly in terms of pressure and temperature. Therefore, as Figure 4C As described, the first diesel injection event (404) is completely removed to prevent premature phasing and / or excessive pressure rise. That is, when the hydrogen-diesel dual-fuel engine (100) is under high operating load, all diesel fuel intended for injection into the cylinder (104) is injected during the second diesel injection event (406). Again, as... Figure 4B As shown, the second diesel injection event (406) extends into the expansion stroke. Furthermore, under high operating loads, less hydrogen is supplied to the hydrogen-diesel dual-fuel engine (100), as... Figure 4CThe reduction in the width of the hydrogen injection event (402) is described. This is to reduce the premixed combustion portion, allowing for better control of the combustion phase, pressure rise rate, and peak cylinder pressure through diesel diffusion combustion.

[0054] The piston cup (308) geometry and multi-stage diesel injection strategy are designed to maintain control over combustion phase and combustion noise, and to tailor charge reactivity and reactivity stratification. The piston cup (308) geometry, diesel injectors (305), and multi-stage diesel injection strategy are further developed in close coordination with the thermal environment in the cylinder. The result is a hydrogen-diesel dual-fuel engine (100) that can operate efficiently across its entire range, from cold starts to high operating loads.

[0055] Figure 5A and 5B The relative positions of the piston crown (302) during the first diesel injection event (404) and the second diesel injection event (406) are depicted respectively. Figure 5A As depicted, the first diesel injection event (404) is positioned relative to the piston crown (302) at the correct time, causing the diesel spray (304) to contact the ramp (501) on the piston cup (308), wherein the ramp is on the outer side of the piston crown (302) relative to the convex radius (315). The contact between the diesel spray (304) and the ramp (501) causes the diesel spray (304) to move outward in the main outward circulation path (502). The main outward circulation path (502) of the diesel spray (304) enhances the charge reactivity in the peripheral region (316).

[0056] The second diesel injection event (406) occurs when the piston is close to the TDC between the compression and expansion strokes. Figure 5B As the piston approaches the TDC, the diesel spray (304) contacts the convex radius (315) of the piston cup (308), and the diesel spray (304) is projected onto the main reverse circulation path (504). Due to the interaction between the diesel spray (304) and the piston cup (308), the diesel trajectory reverses towards the central region (318) to improve the reactivity distribution within the piston cup (308).

[0057] Although Figures 4A to 4C and Figures 5A to 5BFuel injection strategies for a hydrogen-diesel dual-fuel engine (100) under discrete operating loads (e.g., low, medium, and high operating loads) are described; however, those skilled in the art will understand that the fuel injection strategies are not limited to discrete states. According to one or more embodiments, the amount of hydrogen and diesel injected into the hydrogen-diesel dual-fuel engine (100), as well as the timing and duration of the first diesel injection event (404) and the second diesel injection event (406), vary continuously with respect to the operating load. In other words, the amount of hydrogen and diesel, as well as the timing of the injection events, can be specified using a continuous-value function based on continuous (or non-discrete) measurements of the operating load on the hydrogen-diesel dual-fuel engine (100).

[0058] In summary, the fuel injection strategies of the piston crown (302) and the hydrogen-diesel dual-fuel engine (100) are designed to interact synergistically, taking into account the thermal environment of the cylinder (104), to reduce combustion losses and enhance geometry-guided reactivity distribution. For example, given the low auto-ignition tendency of hydrogen, a lean hydrogen-air mixture typically forms in the squeezed region and is the primary source of combustion losses. Therefore, the geometry of the piston cup (308) is designed to reduce squeeze to improve combustion efficiency. Furthermore, the central region (318) is a known source of incomplete combustion products. In the design disclosed above, this problem is addressed by employing a large number of nozzles (i.e., at least 12) on the diesel injector (305) to enhance the charge reactivity in the central region (318). In addition, the convex radius (315) that essentially divides the piston cup (308) into two regions provides an effective means of guiding reactivity distribution through the interaction between the diesel spray (304) and the cup wall (314). Finally, the combustion chamber formed by the piston crown (302) is designed for zero swirl motion to maintain sufficient fuel reactivity stratification. Zero swirl motion and fuel reactivity stratification result in robust control of the combustion process and minimize heat transfer losses in the cylinder.

[0059] As described, the disclosed timing and multi-stage fuel injection strategy allows for controlled fuel reactivity tailored to the operating load of the hydrogen-diesel dual-fuel engine (100). This has a strong influence on the amount and timing of energy released during combustion, where the released energy is realized in the form of heat. Figure 6A and 6B The apparent heat transfer rate (AHRR) is plotted under low to medium operating loads and under high operating loads. Typically, the AHRR curve is closely related to diesel engine performance targets, making it advantageous to tailor the AHRR through designed charge responsiveness, which is controlled as described above. Figure 6A and 6BIn the diagram, the AHRR curve is divided into a first combustion stage (604) and a second combustion stage (606) by a dividing line (602) (the dividing line (602) is for illustrative purposes only).

[0060] Figure 6A The AHRR under low to medium operating loads is described. The energy released during the first combustion stage (604) is initiated during the second diesel injection event (406) and originates from a mild combustion phase of diesel and entrained hydrogen. Under low to medium operating loads, the first combustion stage (604) establishes a thermal environment that leads to and induces the second combustion stage (606). The second combustion stage (606) is characterized by rapid, partially premixed combustion, progressing from a high-reactivity region to a low-reactivity region.

[0061] Figure 6B The AHRR under high operating loads is described. Under high operating loads, cylinder loading increases significantly in terms of pressure and temperature. Therefore, the first diesel injection event (404) is removed (see [link]). Figure 4C This is to prevent premature combustion or excessive pressure rise. Under high operating loads, the first combustion stage (604) is driven by the diffusion of diesel fuel injected as the piston approaches the TDC and hydrogen entrained in the diesel spray (304). The second combustion stage (606) consists primarily of the combustion of residual hydrogen that has been injected and mixed with the intake air and is far from the diesel spray (304). This is because diesel fuel has a higher auto-ignition reactivity than hydrogen, and under high operating loads, at higher cylinder pressures and temperatures, diesel fuel will ignite and burn more quickly. Therefore, diesel fuel does not have as much time to mix with hydrogen before ignition as it does under low operating loads.

[0062] In one aspect, the embodiments disclosed herein relate to a method for operating a hydrogen-diesel dual-fuel engine (100). According to one or more embodiments, Figure 7 The operating strategy for the air handling system of a hydrogen-diesel dual-fuel engine (100) is described. Specifically, Figure 7 The load-speed space during operation of the hydrogen-diesel dual-fuel engine (100) is depicted. Figure 7 The load-speed space is divided into three zones. Each zone is assigned specific settings for the air handling system to optimize the hydrogen-diesel dual-fuel engine (100). Figure 7 The regions shown are speed-invariant, allowing the air handling system settings to change only based on the operating load experienced by the hydrogen-diesel dual-fuel engine (100). Therefore, the regions are appropriately named the low-load region (702), medium-load region (704), and high-load region (706). It should be noted that in... Figure 7The document does not explicitly specify Figure 7 The operating loads depicted indicate the boundary between the low-load region (702) and the medium-load region (704), as well as the operating loads indicating the boundary between the medium-load region (704) and the high-load region (706). Typically, the exact locations of the low-load region (702), the medium-load region (704), and the high-load region (706) in the load-speed space can be set by the user. Furthermore, the load-speed space of the hydrogen-diesel dual-fuel engine (100) can typically be divided into more or fewer than three regions.

[0063] For each zone (low load (702), medium load (704), and high load (706)), the exhaust gas recirculation system (126) with exhaust gas recirculation valve (128) and exhaust gas recirculation cooler (130) is used continuously to control the reactivity of the fuel. The exhaust gas recirculation system (126) is particularly effective in mitigating pre-ignition and preventing engine knock. By preventing pre-ignition and engine knock, more energy can be extracted from the hydrogen content of the dual-fuel system. In addition, the fuels can be mixed more thoroughly to improve fuel efficiency.

[0064] In the low-load region (702), due to the low auto-ignition reactivity of hydrogen, exhaust gas recirculation is used to increase the charge temperature, thereby increasing the ignition tendency. In the medium-load region (704) and the high-load region (706), since the cylinder charge pressure and temperature are sufficiently high, exhaust gas recirculation is not required for thermal boosting. Therefore, the exhaust camshaft switches to the standard lift profile via a two-stage mechanism. Furthermore, in the high-load region (706), in order to maximize hydrogen energy input and enhance partial premixed combustion, charge reactivity must be carefully tailored. This is achieved by implementing a Miller-type LIVC strategy to reduce the effective compression ratio. Finally, the VGT (108) was developed to fully meet the thermal boundary conditions (exhaust gas recirculation and boosting (intake)) of each region (low-load (702), medium-load (704), and high-load (706)).

[0065] Finally, the embodiments disclosed herein relate to methods for operating a hydrogen-diesel dual-fuel engine (100) under warm-up conditions, cold conditions (or cold start), and during a Federal Test Procedure (FTP) cycle (transient operation). According to one or more embodiments, the operation of the hydrogen-diesel dual-fuel engine (100) is controlled by a controller (170) after receiving engine data (160) from a plurality of sensors (150) describing the state of the hydrogen-diesel dual-fuel engine (100). Figures 8A to 8I The document describes advanced operating strategies under warm-up conditions (800°C) (e.g., coolant and oil temperatures of 90°C). Specifically, Figures 8A to 8IThese are labeled graphs, each of which depicts settings such as parameters or relative quantities for a hydrogen-diesel dual-fuel engine (100) disclosed herein relative to a normalized operating load.

[0066] At 0% load, the hydrogen-diesel dual-fuel engine (100) operates using only diesel fuel (i.e., without hydrogen), such as Figure 8A As seen in [the image / document]. Furthermore, at 0% operating load, exhaust gas recirculation (EGR) is not used. Figure 8G ).exist Figure 8G In this context, exhaust gas recirculation is given as a percentage of the volume or number of moles of gas in cylinder (104) relative to the total volume or number of moles of gas in cylinder (104) after the intake stroke, where the total volume consists of exhaust products, hydrogen, diesel fuel, and air. Furthermore, at 0% operating load, diesel fuel is injected in a single stage. The percentage of diesel fuel injected into cylinder (104) during the first injection event relative to the total amount of diesel fuel injected into cylinder during the piston cycle varies with operating load. Figure 8H As given in [the document]. Figure 8H As seen in the diagram, under low load (close to 0%) and high load (close to 100%), the diesel fuel injected into cylinder (104) does not originate from the first diesel injection event (404). That is, under this operating load, only a single diesel injection event is used.

[0067] like Figure 8A As seen in the diagram, hydrogen energy input gradually increases with load, peaking at approximately 80% operating load. Then, hydrogen energy input decreases with further increases in operating load. Note that the hydrogen energy input fraction refers to the percentage of fuel energy input to the cylinder that comes from hydrogen. Figure 8D The global equivalence ratio of the hydrogen, diesel, and air mixture is depicted. By convention, an equivalence ratio of 1 indicates the stoichiometric ratio of fuel (hydrogen and diesel) and air. An equivalence ratio less than 1 indicates a lean hydrogen-diesel-air mixture, and an equivalence ratio greater than 1 indicates a fuel-rich fuel mixture. As described, Figure 8G The proportion of exhaust gas recirculated into cylinder (104) is indicated as a volume percentage of exhaust gas in cylinder (104). The equivalence ratio and exhaust gas recirculation (EGR) ratio are carefully designed to deliver 1 to 2 g / kWh of engine output NO with low pumping losses throughout the entire operating range of the hydrogen-diesel dual-fuel engine (100). x And sufficient boost (i.e., intake compression). The equivalence ratio decreases with changes in operating load. Furthermore, the EGR gradually decreases when transitioning from approximately 30% operating load to full operating load.

[0068] Figure 8B and Figure 8EThe first diesel injection event timing (FDIET) and the second diesel injection event timing (SDIET) are described respectively. For example... Figure 8B As shown, the timing of the first diesel injection event (404) remains relatively constant over a wide range of operating loads; however, as the operating load increases, the timing becomes faster (reducing °aTDC). In contrast, the timing of the second diesel injection event (406) is much more complex and depends on the operating load, such as Figure 8E As illustrated in the diagram. Under low load, SDIET rapidly advances from 0° aTDC to approximately -20° aTDC within about 15% of the operating load. As the load increases, SDIET gradually delays and returns to near 0° aTDC, with the slope of the timing change rate changing by several steps. As SDIET is slowly delayed with increasing load, the combustion process becomes increasingly diffusion-driven. Meanwhile, as... Figure 8C The diesel fuel injection pressure (P) described in the text inj (This is a steady increase in air quality, to achieve good air utilization.)

[0069] As previously combined Figure 7 In the low-load region (702), exhaust gas re-intake is present; however, exhaust gas re-intake is turned off when the operating load of the hydrogen-diesel dual-fuel engine (100) is in the medium-load region (704) and the high-load region (706). Figure 8F Exhaust gas re-inhalation is demonstrated only in the low-load zone (702). According to one or more embodiments, the operating load at which the exhaust gas re-inhalation state is switched (i.e., from on to off, or from off to on) is specified by a first operating load threshold. The first operating load threshold can be specified by the user and does not need to be aligned with any boundary between zones. That is, the first operating load threshold does not need to be equal to the operating load defining the boundary between the low-load zone (702) and the medium-load zone (704). In one or more embodiments, the first operating load threshold is in the range of 25% to 40%.

[0070] In addition, in the high-load region (706), a Miller-type LIVC strategy is adopted to reduce the effective compression ratio in order to customize the charge responsiveness. Figure 8I The diagram illustrates the appropriate engagement of the cam lift to provide LIVC in the high-load region (706). According to one or more embodiments, the operating load at which the state of the LIVC is switched (i.e., from on to off, or from off to on) is specified by a second operating load threshold. This second operating load threshold can be specified by the user and does not need to be aligned with any boundary between regions. That is, the second operating load threshold does not need to be equal to the operating load defining the boundary between the medium-load region (704) and the high-load region (706). In one or more embodiments, the second operating load threshold is in the range of 60% to 80%.

[0071] According to one or more embodiments, the operation method of the hydrogen-diesel dual-fuel engine (100) under warm-up conditions is shown in flowchart form. Figure 9 First, as depicted in box 902, the operating load of the hydrogen-diesel dual-fuel engine (100) is determined by the controller (170) using measurements from multiple sensors (150) disposed on the hydrogen-diesel dual-fuel engine (100). The measurements received by the controller (170) from the multiple sensors (150) are collectively referred to as engine data (160). The operating load is determined as a percentage of the maximum load that the hydrogen-diesel dual-fuel engine (100) can achieve. As previously discussed, there are various settings, parameters, and / or quantities associated with the hydrogen-diesel dual-fuel engine (100). For consistency, the term parameter will be used herein. Thus, it can be said that the operation of the hydrogen-diesel dual-fuel engine (100) is specified by multiple hydrogen-diesel dual-fuel engine parameters. According to one or more embodiments, the value of each of the multiple hydrogen-diesel dual-fuel engine parameters is adjusted by the controller (170) according to the determined operating load, wherein the operating load is determined by the controller (170) using engine data (160). In one or more embodiments, the operation of the hydrogen-diesel dual-fuel engine (100) is specified by a series of functional relationships that relate the expected values ​​of parameters to the operating load. Figures 8A to 8I These parameters are associated with parameters from multiple hydrogen-diesel dual-fuel engines. Therefore, Figures 8A to 8I The functional relationships between several hydrogen-diesel dual-fuel parameters and operating loads were depicted.

[0072] return Figure 9 In the flowchart, in block 904, once the operating load of the hydrogen-diesel dual-fuel engine (100) has been determined, the values ​​of a parameter among a plurality of hydrogen-diesel dual-fuel engine parameters are determined based on that operating load. In other words, a plurality of hydrogen-diesel dual-fuel engine parameters are determined. The plurality of hydrogen-diesel dual-fuel engine parameters include, but are not limited to: hydrogen energy parameter; equivalence ratio parameter; exhaust gas recirculation parameter; first diesel injection event timing parameter; second diesel injection event timing parameter; first diesel injection quantity parameter; exhaust gas re-intake parameter; and delayed intake valve closing parameter. The hydrogen energy parameter corresponds to the amount of energy available to the hydrogen-diesel dual-fuel engine (100) that can be attributed to hydrogen fuel. The equivalence ratio parameter indicates the equivalence ratio of the hydrogen, diesel, and air mixture. Therefore, using the hydrogen energy parameter and the equivalence ratio parameter, the amount of hydrogen and diesel used in the cycle of the hydrogen-diesel dual-fuel engine (100) can be determined.

[0073] Exhaust gas recirculation (EGR) parameters specify the amount of exhaust gas present in the combustion chamber relative to the total amount of contents within the combustion chamber (i.e., exhaust gas and reactants (hydrogen, diesel, air)). In other words, EGR parameters specify the amount of exhaust gas present in the combustion chamber relative to the amount of exhaust gas and reactants.

[0074] The first and second diesel injection timing parameters specify, based solely on crankshaft angle (i.e., piston position), when the first diesel injection event (404) and the second diesel injection event (406) should begin. The first diesel injection quantity parameter indicates how much of the total diesel fuel will be injected into cylinder (104) during the first diesel injection event (404). Therefore, any remaining diesel fuel in the diesel quantity that was not injected into cylinder (104) during the first diesel injection event (404) is injected into cylinder (104) during the second diesel injection event (406). Specifically, the first and second diesel quantities can be determined, wherein the first diesel quantity is injected into the hydrogen-diesel dual-fuel engine (100) during the first diesel injection event (404), and the second diesel quantity is injected into the hydrogen-diesel dual-fuel engine (100) during the second diesel injection event (406). The precise values ​​for the first and second diesel quantities can be determined using knowledge of the total diesel fuel to be injected and the first diesel injection quantity parameter.

[0075] Finally, the exhaust gas re-intake parameters and the delayed intake valve closing parameters only indicate a Boolean state of "on" or "off". Based on the determined operating load, the exhaust gas re-intake parameters and the delayed intake valve closing parameters are determined to be "on" or "off".

[0076] In box 906, once multiple hydrogen-diesel dual-fuel engine parameters have been determined, the parameters among the multiple hydrogen-diesel dual-fuel engine parameters are adjusted to their appropriate values ​​and / or states.

[0077] Figure 10 The operation of the hydrogen-diesel dual-fuel engine (100) under cold conditions (or start-up conditions) and during the FTP cycle is described. Figure 10 The flowchart begins at box 1002. Box 1002 represents a decision. The decision at box 1002 is based on the measured ambient temperature (T). amb ) and the coolant temperature (T) in the hydrogen-diesel dual-fuel engine (100) 冷却剂 ) and oil temperature (T) 油 The temperature of the ambient temperature (T). These temperatures are measured, with one or more thermometers near each temperature location. Specifically, the ambient temperature (T) amb The ambient temperature (T) is measured using one or more thermometers external to the hydrogen-diesel dual-fuel engine (100). ambThe temperature of the environment immediately surrounding the hydrogen-diesel dual-fuel engine (100) is also present. Similarly, the coolant temperature (T0) is... 冷却剂 Use one or more thermometers near the coolant to measure the oil temperature (T). 油 One or more thermometers are used to measure the temperature of the oil near the hydrogen-diesel dual-fuel engine (100). If all these temperatures are below 0°C, the hydrogen-diesel dual-fuel engine (100) is considered to be in a cold start state (or start-up state), and the flowchart proceeds to block 1004. Block 1004 describes in detail the operating procedure of the hydrogen-diesel dual-fuel engine (100) in a cold start state. When in a cold start state, the hydrogen-diesel dual-fuel engine (100) is started and operated by a throttled, spark-initiated, stoichiometric (equivalence ratio = 1) hydrogen flame propagation. That is, in a cold start state, only hydrogen is used as fuel. The hydrogen is mixed with air in a stoichiometric amount and the hydrogen-air mixture is ignited using a spark igniter (306).

[0078] Continuously monitor the ambient temperature (T) amb ), coolant temperature (T) 冷却剂 ) and oil temperature (T) 油 ). The ambient temperature (T) of the hydrogen-diesel dual-fuel engine (100) was measured. amb The coolant temperature (T) is not expected to change with engine operation. However, starting from the initial cold start, as the hydrogen-diesel dual-fuel engine (100) operates, the coolant temperature (T) will increase. 冷却剂 ) and oil temperature (T) 油 The temperature is expected to rise from its initial measurement. If all these temperatures are found to be close to (> 0°C) or exceed 25°C, the hydrogen-diesel dual-fuel engine (100) enters the FTP cycle. Furthermore, as shown in box 1006, although these temperatures may exceed 25°C, the coolant temperature (T... 冷却剂 ) and oil temperature (T) 油 The temperature must be below the predetermined target temperature (T). 目标 ), of which the target temperature (T) 目标 This will be described in more detail below. It should be noted that in some cases, the hydrogen-diesel dual-fuel engine (100) does not first enter a cold-start state. That is, the ambient temperature (T) amb ), coolant temperature (T) 冷却剂 ) and oil temperature (T) 油The temperature can approach 25°C without first operating the hydrogen-diesel dual-fuel engine (100) according to the cold-state operating procedure in block 1004. For consistency, it will be stated below that the hydrogen-diesel dual-fuel engine (100) is in FTP state when the conditions in block 1006 are met. If it is determined in block 1006 that the hydrogen-diesel dual-fuel engine (100) is in FTP state, then the presence of the FTP timer is checked in block 1007. The FTP timer is only checked for the first start of the FTP cycle (t... ftp The time is counted either since the hydrogen-diesel dual-fuel engine (100) entered the FTP state. If the hydrogen-diesel dual-fuel engine (100) enters the FTP state for the first time since startup, there is no FTP timer. In this case, block 1007 proceeds to block 1008, and the FTP timer is started. Once the FTP timer is started, or if a timer is detected, the FTP time (t) is counted. ftp ) and threshold time (t) s The threshold time is compared. In one or more embodiments, the threshold time is set to 370 seconds, which corresponds to the first third of a standard FTP cycle.

[0079] To meet the ultra-low NOx emission standards in the emissions certification cycle x A key technical area of ​​standardization is achieving rapid catalyst heating during the cold FTP cycle. Furthermore, preheating the catalyst during the first third of the FTP cycle is particularly important, during which the engine is significantly idling. If, in box 1009, it is determined that the hydrogen-diesel dual-fuel engine (100) is still within the threshold time (t... s (For example, threshold time (t) s The first part of the FTP cycle, determined by (FTP cycle time / 3), is checked in box 1010 for idling speed (or idle speed). If the hydrogen-diesel dual-fuel engine (100) is in FTP state and the FTP time (t) is... ftp The time (t) is less than the threshold. s And if the engine is at idle speed, then the engine is operated as if it were cold (box 1004). Compared to conventional lean diesel compression ignition, maintaining operation as if the engine were cold to utilize the high flame velocity of hydrogen and provide excellent catalytic ignition performance is advantageous.

[0080] If FTP time (t) ftp Time exceeding the threshold (t) sAlternatively, if the engine speed is greater than the idle speed, the hydrogen-diesel dual-fuel engine (100) is switched to dual-fuel operation, as depicted in box 1012. As the name suggests, in dual-fuel operation, the hydrogen-diesel dual-fuel engine (100) receives both hydrogen and diesel fuel. In this state, the hydrogen-diesel dual-fuel engine (100) is configured to operate with a rich fuel mixture.

[0081] Secondly, continuously monitor the ambient temperature (T). amb ), coolant temperature (T) 冷却剂 ) and oil temperature (T) 油 In box 1006, the coolant temperature (T) is... 冷却剂 ) and oil temperature (T) 油 ) and the predetermined target temperature (T) 目标 ) for comparison. In one or more embodiments, the target temperature (T) is compared. 目标 The value is 90℃. If both of these temperatures are found to be equal to or greater than the target temperature (T), then... 目标 As indicated by box 1014, the hydrogen-diesel dual-fuel engine (100) is considered to be in a warm-up state. It should be noted that the ambient temperature (T...) amb The determination of whether the hydrogen-diesel dual-fuel engine (100) is in a warm-up state is not affected. When in a warm-up state, the hydrogen-diesel dual-fuel engine (100) operates using the previously described warm-up operation method, as shown in box 1016. Once the hydrogen-diesel dual-fuel engine (100) is in a warm-up state, the warm-up operation method (see Figures 8 and 9) is used until the hydrogen-diesel dual-fuel engine (100) is shut down.

[0082] The embodiments of this disclosure can provide at least one of the following advantages. The hydrogen-diesel dual-fuel engine (100) and operating method described herein provide enhanced engine performance by significantly increasing the dual-fuel operating range, reducing combustion losses, improving fuel efficiency, and reducing pollutants. The desired effects are achieved, at least in part, through a combustion chamber design and fuel injection strategy that minimizes compression, promotes fuel reactivity in the central region (318) of the cylinder (104), enhances the geometry-guided reactivity distribution, maintains reactivity stratification, and reduces heat transfer losses in the cylinder by eliminating swirl motion. Furthermore, hydrogen energy input is maximized by using exhaust gas re-inhalation at low loads to increase the charge temperature and using LIVC at high loads to reduce the effective compression ratio, promoting partially premixed combustion and reducing combustion losses. In addition, a customized VGT (108) and exhaust gas recirculation system (126) are configured to effectively control charge reactivity, delivering 1 to 2 g / kWh of engine output NO. x(or less), while providing sufficient boost with low pumping losses. Finally, detailed descriptions of the operation of the full-range fuel injection strategy and air handling system during warm-up conditions are provided, as well as operating instructions for using spark-initiated, stoichiometric hydrogen flame propagation under cold-start and FTP conditions to enhance cold-start and catalytic heating performance.

[0083] Although only a few exemplary embodiments have been described in detail above, those skilled in the art will readily understand that many modifications can be made to the exemplary embodiments without substantially departing from the invention. Therefore, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims.

Claims

1. A hydrogen-diesel dual fuel engine, comprising: an engine block, comprising: a cylinder, wherein the cylinder is equipped with at least two hydrogen fuel injectors; and a piston, wherein the piston is surrounded by the cylinder, and wherein the piston comprises a piston crown; an air handling system, comprising: an intake manifold; an intake pipe, wherein the intake pipe receives air through an air intake and delivers the air to the intake manifold; an exhaust pipe, wherein the exhaust pipe receives exhaust gas and expels at least a portion of the exhaust gas; a variable geometry turbocharger coupled to the intake pipe and the exhaust pipe; and an exhaust gas recirculation system configured to recirculate exhaust gas from the exhaust pipe to the intake manifold; a two-stage camshaft, wherein the two-stage camshaft is configured with the air handling system for exhaust gas re-breathing and late intake valve closing; a port fuel injector system integrated directly with the intake manifold, wherein the port fuel injector system provides hydrogen gas to the at least two hydrogen fuel injectors; a diesel injector configured to inject diesel into the cylinder; a common rail fuel injection system configured to supply diesel to the diesel injector; a plurality of sensors, comprising: a temperature sensor, and a tachometer; and a controller configured to receive engine data from the plurality of sensors and configured to control operation of the hydrogen-diesel dual fuel engine, wherein the controller is configured to collectively operate the two-stage camshaft, the exhaust gas recirculation system, and the variable geometry turbocharger to maintain a NOx production below 2 g / kWh.

2. The hydrogen-diesel dual fuel engine of claim 1, wherein the air handling system further comprises: a charge air cooler; an idle air control valve; an exhaust back pressure valve; an exhaust gas recirculation valve; and an exhaust gas recirculation cooler.

3. The hydrogen-diesel dual fuel engine of claim 1 or 2, further comprising: a spark igniter, wherein the spark igniter is configured to produce a spark in the cylinder.

4. The hydrogen-diesel dual fuel engine of any of claims 1-3, wherein the controller determines an operating load of the hydrogen-diesel dual fuel engine based on the engine data.

5. The hydrogen-diesel dual fuel engine of claim 4, wherein at a low operating load, the controller is configured to adjust the two-stage camshaft to use exhaust gas re-breathing and not to use late intake valve closing, wherein at a medium operating load, the controller is configured to adjust the two-stage camshaft to not use exhaust gas re-breathing and not to use late intake valve closing, and wherein at a high operating load, the controller is configured to adjust the two-stage camshaft to not use exhaust gas re-breathing and to use late intake valve closing.

6. The hydrogen-diesel dual fuel engine of any of claims 1-5, wherein the piston crown comprises a substantially annular piston bowl defined by a conical center and a bowl wall; wherein the bowl wall contains a convex radius, and wherein the convex radius divides a volume of the piston bowl into a peripheral region and a central region. ​ 7. The hydrogen-diesel dual fuel engine of any one of claims 1 to 6, wherein the diesel injector has at least 12 nozzles.

8. A method for operating a hydrogen-diesel dual fuel engine under a warm-up condition, comprising: determining an operating load of the hydrogen-diesel dual fuel engine; determining a plurality of hydrogen-diesel dual fuel engine parameters based on the operating load; and adjusting the plurality of hydrogen-diesel dual fuel engine parameters; wherein the plurality of hydrogen-diesel dual fuel engine parameters comprises: a hydrogen energy parameter; an equivalence ratio parameter; an exhaust gas recirculation parameter; a first diesel injection event timing parameter; a second diesel injection event timing parameter; a first diesel injection amount parameter; an exhaust gas re-breathing parameter; and a late intake valve closing parameter.

9. The method of claim 8, further comprising: determining an amount of hydrogen and an amount of diesel to inject into the hydrogen-diesel dual fuel engine using at least in part the hydrogen energy parameter and the equivalence ratio parameter.

10. The method of claim 8 or 9, wherein the exhaust gas recirculation parameter specifies an amount of exhaust gas relative to an amount of exhaust gas and an amount of air.

11. The method of any one of claims 8 to 10, wherein the exhaust gas re-breathing parameter is set to an off state when the operating load exceeds a first operating load threshold, wherein the first operating load threshold is in a range of 25% to 40%.

12. The method of any one of claims 8 to 10, wherein the late intake valve closing parameter is set to an on state when the operating load is greater than a second operating load threshold, wherein the second operating load threshold is in a range of 60% to 80%.

13. The method of claim 9, further comprising: determining a first diesel amount; and determining a second diesel amount, wherein the first diesel amount and the second diesel amount are determined using at least in part the diesel amount and the first diesel injection amount parameter, wherein the first diesel amount is injected into the hydrogen-diesel dual fuel engine during a first diesel injection event and the second diesel amount is injected into the hydrogen-diesel dual fuel engine during a second diesel injection event.

14. A method for operating a hydrogen-diesel dual fuel engine, comprising: determining an ambient temperature, wherein the ambient temperature is a temperature of an ambient environment of the hydrogen-diesel dual fuel engine; determining a coolant temperature, wherein the coolant temperature is a temperature of a coolant in the hydrogen-diesel dual fuel engine; determining an oil temperature, wherein the oil temperature is a temperature of an oil in the hydrogen-diesel dual fuel engine; receiving a target temperature; determining a state of the hydrogen-diesel dual fuel engine based on the ambient temperature, the coolant temperature, the oil temperature, and the target temperature; and selecting an operating method based at least on the state of the hydrogen-diesel dual fuel engine.

15. The method of claim 14, wherein the state of the hydrogen-diesel dual fuel engine is one of a cold state, a federal test procedure (FTP) state, and a warm state. ​ ​ 16. The method of claim 14 or 15, wherein the ambient temperature is measured using at least one thermometer located outside of the hydrogen-diesel dual fuel engine, wherein the coolant temperature is measured using at least one thermometer proximate to the coolant, and wherein the oil temperature is measured using at least one thermometer proximate to the oil.

17. The method of claim 15, wherein when it is determined that the hydrogen-diesel dual fuel engine is in the FTP state, the method further comprises: determining whether an FTP timer has been started; starting the FTP timer, wherein the FTP timer counts an FTP time since the FTP timer was started; comparing the FTP time to a threshold time; and determining whether the hydrogen-diesel dual fuel engine is idling.

18. The method of claim 15, wherein when it is determined that the hydrogen-diesel dual fuel engine is in the cold engine state, the hydrogen-diesel dual fuel engine uses a stoichiometric mixture of hydrogen gas and air as fuel.

19. The method of claim 17, wherein when the FTP time is less than the threshold time and when the hydrogen-diesel dual fuel engine is idling, the hydrogen-diesel dual fuel engine uses a rich fuel mixture of air, hydrogen gas, and diesel.

20. The method of claim 15, wherein when it is determined that the hydrogen-diesel dual fuel engine is in the warm engine state, the hydrogen-diesel dual fuel engine is operated according to a warm engine operating method.

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