High efficiency exhaust gas return system

Abstract

A gas mixer comprising: a converging-diverging nozzle (206) including a converging portion (208a) and a diverging portion (208b) and defining a first gas flow path; an air housing including an air inlet (212) configured to supply air to the first gas flow path upstream of the converging-diverging nozzle; a gas housing defining a second gas flow path and including a first gas inlet (222) configured to receive a secondary gas and allow the secondary gas to enter the second gas flow path, and a gas nozzle (220) positioned in the converging portion of the converging-diverging nozzle in parallel with and centered within the first gas flow path, the gas nozzle configured to supply the secondary gas to the first gas flow path upstream of the diverging portion.

Description

[0001] Priority Statement

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 107,706, filed October 30, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to exhaust gas recirculation (EGR) systems for internal combustion engines. Background Technology

[0004] Exhaust gas recirculation, particularly cooled EGR (cEGR), can be added to internal combustion engine systems to reduce NOx emissions and decrease knocking tendency. In such systems, a certain amount of exhaust gas is added to the air and / or fuel mixture within the engine's intake manifold. The challenge lies in the cost of delivering cEGR, especially for highly efficient engines, which are typically most efficient when exhaust manifold pressures are lower than intake manifold pressures. This pressure differential creates a positive scavenging pressure differential across the engine, scavenging combustion gases from the cylinder wells and providing good pressure-volume pumping circuit operation. A particularly challenging aspect is delivering cEGR from its source in the exhaust manifold to the intake manifold without negatively impacting residual gas scavenging and engine cycle efficiency via the pumping circuit. The "classic" high-pressure loop cEGR system directs exhaust gases directly into the intake manifold. This requires designing or using variable turbocharging to force the exhaust manifold pressure to be higher than the intake manifold pressure. This, in turn, negatively reduces scavenging of hot, burned gases and the engine's P-V cycle, resulting in efficiency losses. Since the purpose of cEGR is to reduce knocking tendency to improve efficiency and power density, this is particularly counterproductive. However, this classic method of driving EGR actually increases knocking tendency by retaining residual gases and reduces efficiency by doing work under negative pressure on the engine—that is, taking two steps forward to reduce cEGR knocking, but a step backward due to its pumping method—resulting in a zero-gain point where the cost of driving cEGR offsets the benefits of delivering it. Summary of the Invention

[0005] In general, this disclosure describes techniques related to recirculating exhaust gases.

[0006] In a first example, the gas mixer includes: a converging-diverging nozzle including a converging portion and a diverging portion and defining a first gas flow path; an air housing including an air inlet configured to supply air to the first gas flow path upstream of the converging-diverging nozzle; and a gas housing defining a second gas flow path and including a first gas inlet and a gas nozzle, the first gas inlet configured to receive secondary gas and allow the secondary gas to enter the second gas flow path, the gas nozzle positioned in the converging portion of the converging-diverging nozzle parallel to and centered within the first gas flow path, and the gas nozzle configured to supply secondary gas to the first gas flow path upstream of the diverging portion.

[0007] In the second example according to Example 1, the gas housing also includes a second gas inlet to allow access to the interior of the subgas housing.

[0008] In the third example according to Example 2, the first gas inlet is configured to receive exhaust gas from the first cylinder of the engine, and the second gas inlet is configured to receive exhaust gas from the second cylinder of the engine, wherein the first cylinder and the second cylinder alternately supply exhaust gas during engine operation.

[0009] In the fourth example according to Example 3, the first gas inlet is in fluid communication with the first exhaust manifold, and the second gas inlet is in fluid communication with the second exhaust manifold.

[0010] In the fifth example according to Example 2 or 3, the gas mixer also includes a check valve configured to prevent backflow in the first gas inlet and the second gas inlet.

[0011] In the sixth example according to Example 5, the check valve includes a valve configured to block gas flow along a second gas inlet based on gas flow along a first gas inlet, the valve also configured to block gas flow along the first gas inlet based on gas flow along the second gas inlet.

[0012] In the seventh example according to any one of Examples 1 to 6, the gas mixer further includes a fuel inlet connected to the gas mixer and including a fuel inlet pipe positioned parallel to and centered within the second gas flow path, the fuel inlet pipe being configured to supply fuel into the second gas flow path upstream of the gas nozzle.

[0013] In the eighth example, an engine system includes: an intake manifold configured to receive a combustible mixture configured to burn in a combustion chamber; a throttle valve located upstream of the intake manifold and configured to at least partially regulate the airflow entering the intake manifold; an exhaust manifold configured to receive combustion products from the combustion chamber; and a gas mixer located downstream of the throttle valve and upstream of the intake manifold, the gas mixer including: a converging-diverging nozzle including a converging portion and a diverging portion and defining a first gas flow path; an air housing including an air inlet configured to supply air to the first gas flow path upstream of the converging-diverging nozzle; a gas housing defining a second gas flow path and including: a first gas inlet configured to receive a secondary gas and allow the secondary gas to enter the second gas flow path; and a gas nozzle positioned parallel to and centered within the first gas flow path in the converging portion of the converging-diverging nozzle, the gas nozzle configured to supply the secondary gas to the first gas flow path upstream of the diverging portion.

[0014] In the ninth example according to Example 8, the first gas inlet is configured to receive exhaust gas recirculated gas from the exhaust manifold.

[0015] In the tenth example according to Example 8 or 9, the gas mixer further includes a second gas inlet, wherein the exhaust manifold includes a first exhaust gas sub-manifold in fluid communication with the first gas inlet and a second exhaust gas sub-manifold in fluid communication with the second gas inlet.

[0016] In the eleventh example according to Example 10, a first exhaust gas submanifold is configured to receive exhaust gas from a first cylinder of the engine system, and a second exhaust gas submanifold is configured to receive exhaust gas from a second cylinder of the engine system, wherein the first cylinder and the second cylinder are configured to alternately supply exhaust gas during engine system operation.

[0017] In the twelfth example according to Example 10 or 11, the gas mixer also includes a check valve configured to prevent backflow in the first gas inlet and the second gas inlet.

[0018] In the thirteenth example according to Example 12, the check valve includes a valve configured to block gas flow along a second gas inlet based on gas flow along a first gas inlet, the valve also configured to block gas flow along the first gas inlet based on gas flow along the second gas inlet.

[0019] In the fourteenth example according to any one of Examples 8 to 13, the engine system also includes a compressor located upstream of the throttle valve, which causes an increase in pressure within the first gas flow path.

[0020] In the fifteenth example according to Example 14, the engine system also includes a turbine located downstream of the exhaust manifold, which is coupled to the compressor and configured to rotate the compressor.

[0021] In the sixteenth example according to any one of Examples 8 to 15, the engine system further includes an exhaust gas cooler located within the flow path between the exhaust manifold and the gas mixer, and configured to reduce the temperature of the exhaust gas before the gas mixer.

[0022] In the seventeenth example according to any one of Examples 8 to 16, the gas mixer further includes a fuel inlet connected to the gas mixer and including a fuel inlet pipe positioned parallel to and centered within the second gas flow path, the fuel inlet pipe being configured to supply fuel into the second gas flow path upstream of the gas nozzle.

[0023] In an example embodiment, a gas mixer includes: a converging-diverging nozzle having a converging portion and a diverging portion and defining a first gas flow path; an air housing having an air inlet configured to supply air to the first gas flow path upstream of the converging-diverging nozzle; and a gas housing defining a second gas flow path and having a first gas inlet and a gas nozzle, the first gas inlet configured to receive secondary gas and allow the secondary gas to enter the second gas flow path, the gas nozzle positioned in the converging portion of the converging-diverging nozzle parallel to and centered within the first gas flow path, and the gas nozzle configured to supply secondary gas to the first gas flow path upstream of the diverging portion.

[0024] Various embodiments may include some, all, or none of the following features. The gas housing may include a second gas inlet for allowing secondary gas to enter the interior of the gas housing. A first gas inlet may be configured to receive exhaust gas from a first cylinder of the engine, and a second gas inlet may be configured to receive exhaust gas from a second cylinder of the engine, wherein the first and second cylinders alternately supply exhaust gas during engine operation. The first gas inlet may be in fluid communication with a first exhaust manifold, and the second gas inlet may be in fluid communication with a second exhaust manifold. The gas mixer may also include a check valve configured to prevent backflow in the first and second gas inlets. The check valve may include a valve configured to block gas flow along the second gas inlet based on gas flow along the first gas inlet, and the valve is also configured to block gas flow along the first gas inlet based on gas flow along the second gas inlet. The gas mixer may include a fuel inlet connected to the gas mixer and has a fuel inlet pipe positioned parallel to and centered within a second gas flow path, the fuel inlet pipe being configured to supply fuel into the second gas flow path upstream of a gas nozzle.

[0025] In another example embodiment, an engine system includes: an intake manifold configured to receive a combustible mixture configured to burn in a combustion chamber; a throttle valve located upstream of the intake manifold and configured to at least partially regulate the airflow entering the intake manifold; an exhaust manifold configured to receive combustion products from the combustion chamber; and a gas mixer located downstream of the throttle valve and upstream of the intake manifold, the gas mixer including: a converging-diverging nozzle including a converging portion and a diverging portion and defining a first gas flow path; an air housing having an air inlet configured to supply air to the first gas flow path upstream of the converging-diverging nozzle; a gas housing defining a second gas flow path and including: a first gas inlet configured to receive a secondary gas and allow the secondary gas to enter the second gas flow path; and a gas nozzle positioned parallel to and centered within the first gas flow path in the converging portion of the converging-diverging nozzle, the gas nozzle configured to supply the secondary gas to the first gas flow path upstream of the diverging portion.

[0026] Various embodiments may include some, all, or none of the following features. A first gas inlet may be configured to receive exhaust gas recirculated from an exhaust manifold. A gas mixer may include a second gas inlet, and the exhaust manifold may include a first exhaust gas sub-manifold in fluid communication with the first gas inlet and a second exhaust gas sub-manifold in fluid communication with the second gas inlet. The first exhaust gas sub-manifold may be configured to receive exhaust gas from a first cylinder of the engine system, and the second exhaust gas sub-manifold may be configured to receive exhaust gas from a second cylinder of the engine system, wherein the first and second cylinders are configured to alternately supply exhaust gas during engine system operation. The engine system may include a check valve configured to prevent backflow in the first and second gas inlets. The check valve may include a valve configured to block gas flow along the second gas inlet based on gas flow along the first gas inlet, and the valve is also configured to block gas flow along the first gas inlet based on gas flow along the second gas inlet. The engine system may include a compressor upstream of a throttling element, the compression mechanism causing an increase in pressure within the first gas flow path. The engine system may include a turbine located downstream of an exhaust manifold, coupled to a compressor and configured to rotate the compressor. The engine system may include an exhaust gas cooler positioned within a flow path between the exhaust manifold and a gas mixer, configured to reduce the temperature of the exhaust gases before the gas mixer. The gas mixer may include a fuel inlet coupled to the gas mixer and having a fuel inlet pipe positioned parallel to and centered within a second gas flow path, the fuel inlet pipe configured to supply fuel into the second gas flow path upstream of a gas nozzle.

[0027] The systems and technologies described herein offer one or more of the following advantages: First, the system can provide high engine power density. Second, the system can increase engine efficiency by reducing the engine exhaust pumping work associated with turbocharging. Third, the system can produce near-zero emissions. Fourth, the system can reduce methane leakage (CH4) within the engine's knock limits. Fifth, the system can improve engine operation by increasing the use of exhaust gas recirculation.

[0028] Details of one or more embodiments are set forth in the accompanying drawings and the following description. Other features and advantages will become apparent from the description, drawings, and claims. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of an exemplary internal combustion engine system.

[0030] Figure 2 This is a half-sectional view of an exemplary gas mixer.

[0031] Figure 3A - 3D is another example of various views of a gas mixer. Detailed Implementation

[0032] The technical goal of gas turbine engine development is to achieve high efficiency and high power density, but with near-zero emissions, especially with no methane leakage (CH4) within the knock limits of the gas turbine engine. High-efficiency gas turbine engines use excess air to reduce NOx and improve efficiency. While lean engines can meet NOx levels and efficiency requirements, methane leakage remains unresolved. To reduce / eliminate methane leakage, catalysts can be used. The most available and economical catalyst is the three-way catalytic converter (TWC). For this type of catalyst to work, combustion needs to be stoichiometric (chemically equivalent). To lower combustion temperatures and improve efficiency associated with stoichiometric combustion, cooled exhaust gas recirculation (EGR) is used. Conventional EGR systems introduce high pumping work, which leads to an overall reduction in engine efficiency. High efficiency can be achieved through high compression ratios, forward-progressing combustion phases, low heat transfer, and high polytropic compression efficiency of the gas. This goal can be achieved using high levels of EGR. Thermodynamically, the more EGR used, the better the results within the limits of deteriorating combustion quality (e.g., combustion duration, stability).

[0033] Using EGR can have parasitic effects on the engine system; that is, it can reduce the engine's effective power output because energy is required to move exhaust gases from the exhaust manifold to the intake manifold. This is particularly problematic in turbocharged engines where intake manifold pressure may be higher than exhaust manifold pressure. Ironically, EGR is most needed when intake manifold pressure is high, such as when the engine is running under high load. In the case of turbocharged engines, increased back pressure in the exhaust manifold can also lead to knocking under high load.

[0034] This paper presents a concept for an EGR system that can be used on internal combustion engines, including turbocharged internal combustion engines. In the engine's intake system, a jet pump is added between the throttle valve and the intake manifold. If a compressor is present in the intake system, the jet pump can be placed downstream of the compressor (although it can also be placed upstream). Recirculated exhaust gas or other gases (e.g., ammonia, hydrogen) flow from the throttle valve into the intake manifold, passing through the central flow path of the jet pump. In the low-pressure receiver region within the jet pump, air is added to the flow from the exhaust manifold. The lower effective pressure in the receiver allows a pressure differential to form between the gas (e.g., exhaust or other gas) manifold and the receiver. The reverse Bernoulli effect restores pressure by slowing down the high-speed / low-pressure gas, thereby generating a pressure in the intake manifold equal to or higher than that in the gas manifold. Therefore, at the system level, the jet pump draws gas from the gas manifold to the intake manifold even when the gas manifold is at a lower pressure. Fuel can be added to the airflow upstream of the converging end of the converging nozzle. As the three streams combine within the jet pump to create turbulence, this results in a well-mixed combustible mixture flowing into the intake manifold.

[0035] Figure 1 An exemplary engine system 100 is illustrated. Engine system 100 includes an intake manifold 104 configured to receive a combustible mixture to be burned in the combustion chamber of engine 100. Specifically, intake manifold 104 is fluidly coupled to an oxygen (e.g., air) source and a fuel source. The combustible mixture may include air and any combustible fluid, such as natural gas, atomized gasoline, or diesel. Engine system 100 includes cylinder banks 102a and 102b, each with four cylinders. While the illustrated embodiment includes an eight-cylinder engine with two cylinder banks of four cylinders each, engine system 100 may have any number of cylinder banks with any appropriate number of cylinders. Furthermore, although the illustrated example is depicted and described as a piston engine, aspects of this disclosure are applicable to other types of internal combustion engines, such as rotary engines or gas turbines.

[0036] Throttle valve 112 is located in intake chamber 103 upstream of intake manifold 104. Throttle valve 112 is configured to regulate the airflow from the surrounding environment 116 through intake chamber 103 into intake manifold 104, for example, by changing the cross-sectional area of ​​the flow path through throttle valve 112. In some embodiments, throttle valve 112 may include a butterfly valve or a disc valve. Reducing the cross-sectional area of ​​the flow path through throttle valve 112 reduces the velocity of air flowing through throttle valve 112 into intake manifold 104.

[0037] Exhaust manifold 106a is configured to receive combustion products (exhaust) from the combustion chamber of cylinder bank 102a. Specifically, exhaust manifold 106a is fluidly connected to the outlet of the combustion chamber of cylinder bank 102a. EGR passage 108a or conduit is fluidly connected to exhaust manifold 106a and gas mixer 114. In the illustrated embodiment, EGR throttle valve 126a is located within EGR passage 108a between exhaust manifold 106a and gas mixer 114 and is used to regulate EGR flow. EGR throttle valve 126a regulates EGR flow by adjusting the cross-sectional area of ​​EGR passage 108a through which EGR throttle valve 126a passes. In some embodiments, EGR throttle valve 126a may include a butterfly valve, disc valve, needle valve, or other valve type.

[0038] Exhaust gas cooler 110a is located in the EGR channel 108a between exhaust manifold 106a and gas mixer 114. Exhaust gas cooler 110a can operate to reduce the temperature of exhaust gas before it enters gas mixer 114. Exhaust gas cooler 110a is a heat exchanger, such as an air-to-air exchanger or an air-to-water exchanger.

[0039] Exhaust manifold 106b is configured to receive combustion products (exhaust) from the combustion chamber of cylinder bank 102b. Specifically, exhaust manifold 106b is fluidly connected to the outlet of the combustion chamber of cylinder bank 102b. EGR passage 108b or conduit is fluidly connected to exhaust manifold 106b and gas mixer 114. In the illustrated embodiment, EGR throttle valve 126b is located within EGR passage 108b between exhaust manifold 106b and gas mixer 114 and is used to regulate EGR flow. EGR throttle valve 126b regulates EGR flow by adjusting the cross-sectional area of ​​EGR passage 108b through which it passes. In some embodiments, EGR throttle valve 126b may include a butterfly valve, disc valve, needle valve, or another valve type.

[0040] The exhaust gas cooler 110b is located in the EGR channel 108b between the exhaust manifold 106b and the gas mixer 114. The exhaust gas cooler 110b can operate to reduce the temperature of the exhaust gas before it enters the gas mixer 114. The exhaust gas cooler 110b is a heat exchanger, such as an air-to-air exchanger or an air-to-water exchanger.

[0041] In the example shown, engine system 100 is configured such that essentially only one cylinder bank of cylinders 102a and 102b receives exhaust gas at any given time. For example, cylinders of cylinder bank 102a may be in their exhaust stroke while cylinders of cylinder bank 102b are in their intake, compression, or combustion stroke, and similarly, cylinders of cylinder bank 102b may be in their exhaust stroke while cylinders of cylinder bank 102a are in their intake, compression, or combustion stroke. In other words, in some embodiments, engine system 100 may be configured such that EGR gas flows in alternating pulses between EGR passages 108a and 108b.

[0042] EGR channels 108a and 108b are fed into the gas mixer 114. In the illustrated example, the gas mixer 114 is located downstream of the throttle valve 112 and upstream of the intake manifold 104. The gas mixer 114 is located in the engine intake system and is fluidly connected to the throttle valve 112, the intake manifold 104, and the EGR channels 108a and 108b. Although the illustrated example depicts and describes an engine system 100 having two EGR channels, in some embodiments, the engine system may have one, two, three, four, or any other suitable number of EGR channels. The fluid connection may be made of a conduit containing channels that allow fluid flow. In some embodiments, the gas mixer 114 may be included within a conduit connecting the intake manifold 104 to the throttle valve 112, within the intake manifold 104 itself, within the EGR channels 108a and / or 108b, integrated within the throttle valve 112, or integrated within the EGR throttle valves 126a and / or 126b. Details of the exemplary EGR mixer will be described below in this disclosure.

[0043] In some embodiments, engine system 100 includes a compressor 118 located upstream of throttle valve 112. In engines with compressor 118 but without a throttle, such as diesel engines without a throttle, throttle valve 112 is not required, and air-fuel mixer 114 may be located downstream of compressor 118. Compressor 118 may include a centrifugal compressor, a positive displacement compressor, or other types of compressors used to increase the pressure within intake chamber 103 during engine operation.

[0044] In the example shown, compressor 118 is part of a turbocharger. Specifically, turbine 122 is located downstream of exhaust manifolds 106a and 106b and rotates as exhaust gases expand through turbine 122. Turbine 122 is connected to compressor 118, for example, via a shaft, and causes compressor 118 to rotate. Although the example shown depicts and describes a turbocharger to increase intake manifold pressure, other compression methods, such as electrically or engine-driven compressors (e.g., superchargers), can also be used.

[0045] Engine system 100 includes an intercooler 120 configured to cool compressed air in intake chamber 103 before it enters air mixer 114 and intake manifold 104. Exhaust gas cooler 110a is located in EGR passage 108a between exhaust manifold 106a and air mixer 114. Exhaust gas cooler 110b is located in EGR passage 108b between exhaust manifold 106b and air mixer 114. Exhaust gas coolers 110a and 110b can operate to reduce the temperature of exhaust gases before EGR mixer 114. Exhaust gas coolers 110a and 110b are heat exchangers, such as air-to-air or air-to-water exchangers.

[0046] In some embodiments, other gases or additives may be mixed with or used in place of the EGR gas. For example, pressurized ammonia, hydrogen, methane, or any other suitable substance may be added to the EGR gas upstream of the gas mixer. In another example, pressurized ammonia, hydrogen, methane, or any other suitable substance may be supplied to the gas mixer 114 in complete place of the EGR gas.

[0047] Fuel supply unit 130 is configured to provide fuel for combustion in engine system 100 (e.g., in the cylinders of cylinder banks 102a and 102b). In the example shown, fuel supply unit 130 is configured to supply fuel to gas mixer 114. Figure 2 Examples of this configuration are discussed in more detail in the description. In some embodiments, the fuel supply unit 130 may be configured to supply fuel to the intake chamber 103 (e.g., upstream of the throttle valve 112 and / or the gas mixer 114). In some embodiments, the fuel supply unit 130 may be configured to supply fuel downstream from the gas mixer 114 (e.g., to the intake manifold 104 by direct injection into the cylinder).

[0048] In some embodiments, the fuel supply unit 130 may be a high-pressure fuel supply unit. For example, the fuel supply unit may be configured to provide pressurized gaseous ammonia, hydrogen, methane, or any other suitable combustible gas. In another example, the fuel supply unit may be configured to provide liquefied ammonia, hydrogen, methane, or any other suitable combustible gas, which may be stored and / or provided in liquefied form.

[0049] Figure 2 This is a half-sectional view of an exemplary gas mixer 200. In some embodiments, the gas mixer 200 may be... Figure 1Gas mixer 114. Gas mixer 200 includes a gas housing 202 defining a mixing chamber 204 having an airflow path 205. The mixing chamber 204 is configured as a converging-diverging nozzle 206 having a conical converging portion 208a and a conical diverging portion 208b, the airflow path 205 contracting in the conical converging portion and expanding in the conical diverging portion to an outlet 210. In some embodiments, the outlet 210 may be fluidly connected to an intake manifold, such as Figure 1 An example intake manifold 104.

[0050] The gas mixer 200 includes an air inlet 212 leading to a converging-diverging nozzle 206. In some embodiments, the air inlet 212 may be fluidly connected to an intake chamber, such as... Figure 1 An exemplary intake chamber 103. A conical converging portion 208a defines an air nozzle for the incoming airflow. Typically, air flows in through an air inlet 212 upstream of the converging-diverging nozzle 206, converges in the conical converging portion 208a, diffuses in the conical diverging portion 208b, and exits through an outlet 210, all along the airflow path 205. The converging portion 208a converges along the flow direction toward the converging end. That is, the cross-sectional area of ​​the downstream end (outlet) of the converging portion 208a is smaller than the cross-sectional area of ​​the upstream end (air inlet 212) (e.g., smaller flow area). The conical diverging portion 208b diverges along the flow direction toward the diverging end near the outlet 210. That is, the cross-sectional area of ​​the downstream end (outlet 210) of the converging portion 208a is larger than the cross-sectional area of ​​the upstream end (e.g., smaller flow area).

[0051] The narrowing of the converging portion 208a increases the velocity of the airflow as it passes through the airflow path 205. In the converging portion 208b, the cross-section of the flow path along the airflow path 205 increases. This increase in cross-sectional area slows the flow velocity and increases the pressure of the fluid flow. In some cases, the increase in cross-sectional area can be sized to increase the pressure within the gas mixer 200, such that the pressure drop across the gas mixer 200 is zero, nominal, or small. In some embodiments, the converging-diverging nozzle 206 includes a threaded or other form of removable attachment (e.g., a hose clamped around a flange) at the air inlet 212, outlet 210, or both, to allow the converging-diverging nozzle 206 to be mounted and fluidly connected to the rest of the air intake of the engine system 100. Similarly, in some embodiments, the conical converging portion 208a and the conical diverging portion 208b can be modularly interchanged with each other and / or modularly interchanged with gas nozzles 220 of different geometries and configurations, so that the system can be easily modified to suit a variety of engine applications.

[0052] Gas mixer 200 includes a gas nozzle 220 and a gas inlet 222. Gas inlet 222 is configured to receive a secondary gas (e.g., EGR gas) and define a secondary gas flow path 226 through gas nozzle 220. Gas nozzle 220 is positioned parallel to and centered within air flow path 205 and is configured to supply secondary gas (e.g., flowing along secondary gas flow path 226) to air flow path 205 within a converging portion 208a upstream of the diverging portion 208b of converging-diverging nozzle 206. Gas nozzle is configured to define a secondary gas flow complementary to (e.g., cooperative, substantially parallel to) the air flow along air flow path 205.

[0053] In some embodiments, the converging-diverging nozzle 206 is modularly interchangeable with converging-diverging nozzles 206 of different geometries, making the system easily adaptable to various engine applications. For example, the converging-diverging nozzle 206 may be provided with threads or another form of removable attachment for attachment to the remainder of the mixer housing 202. The example shown illustrates a conical converging portion 208a, a conical diverging portion 208b, and converging-diverging nozzles 206 aligned on the same central axis, but in some embodiments, these components may be misaligned or non-parallel. For example, space constraints may require the gas mixer 200 to have an angle between the axes of the conical converging portion 208a and the conical diverging portion 208b. In some embodiments, the flow path may be curved, rather than as... Figure 2 The roughly horizontal DC path is shown.

[0054] The gas mixer includes a fuel inlet 230, which is configured to supply fuel from sources such as fuel inlets. Figure 1 An exemplary fuel supply unit, such as fuel supply unit 130, receives fuel. Fuel inlet 230 is fluidly connected to a collection of fuel inlet pipes 232a and 232b. Fuel inlet pipes 232a and 232b are configured as fuel nozzles to supply fuel to a second flow path upstream of a converging nozzle, thereby supplying fuel to a secondary gas flow path 226. Fuel inlet pipe 232a is positioned parallel to and centered within the second flow path, configured to supply fuel to the secondary gas flow path 226 upstream of the gas nozzle 220. Fuel inlet pipe 232b is positioned about the inner circumference of the gas nozzle 220 and configured to supply fuel in the secondary gas flow path 226 near the outlet of the gas nozzle 220. Fuel inlet pipes 232a-232b are configured to define a fuel flow complementary to (e.g., cooperative, substantially parallel to) the secondary gas flow along the secondary gas flow path 226. In some embodiments, fuel may be received at high pressure (e.g., liquefied natural gas at 4-12 bar). When the fuel leaves the fuel inlet pipes 232a-232b, the fuel flow helps drive the secondary airflow.

[0055] In some embodiments, fuel inlet 230 may be a gaseous fuel inlet coupled to a gaseous fuel source. However, the fuel delivered by fuel inlet 230 may include any combustible fluid, such as natural gas, gasoline, or diesel. Although shown as a single pipe, fuel inlet 230 may be constructed in other ways, such as as a cross section through a flow region of the mixer, as a fuel delivery orifice along the perimeter of the flow region, or otherwise. While the example shown illustrates fuel inlet pipes 232a-232b configured to inject fuel upstream of divergence section 208b, fuel may also be added via a fuel supply port upstream of air inlet 212 or gas inlet 222. Such a port may include a gaseous fuel supply port. In some cases, fuel may be delivered at high speeds, up to and including a sonic flow at fuel inlet pipes 232a-232b, thereby also creating a fuel-gas jet pump, which allows the fuel to provide additional power for entering and passing through the secondary gas flow path 226 of gas nozzle 220. In this example, higher pressures may generate a sonic jet that can further enhance the mixing of fuel and air. In some implementations, this can reduce the need for a fuel pressure regulator. Furthermore, if the fuel jet is cooled by the Joule-Thompson effect, this cooling effect can cool the air / fuel flow, thereby reducing the size and / or requirement of intake cooling (e.g., intercooler 120).

[0056] In some embodiments, fuel inlet 230 may be a high-pressure fuel inlet. For example, high-pressure gaseous fuel (e.g., H2, NH3, or methanol or other low-carbon fuels at approximately 10–500 bar) may be supplied through fuel inlet pipes 262a–262b to help accelerate airflow. In another example, liquefied gaseous fuel (e.g., liquefied natural gas, NH3, H2) may be heated under liquid conditions and then supplied through fuel inlet pipes 262a–262b, wherein the liquefied gaseous fuel may be injected into the air or EGR stream and “flash” to produce a very high-velocity (e.g., acoustic) jet, thus the added heat increases the pumping effect.

[0057] In some embodiments, the gas mixer 200 may be used in alternative configurations. For example, EGR is not typically used in diesel engine applications. However, other gases, such as ammonia, may be supplied as a secondary gas at gas inlet 222 and combined with diesel fuel flowing through fuel inlet pipes 232a-232b to accelerate the intake air. In one specific example, ammonia may be supplied at 50 bar and mixed in the gas mixer 200 to produce a stoichiometric mixture (e.g., 15% ammonia and 85% air).

[0058] The gas mixer 200 also includes a check valve 260 having two gas inlets. The check valve 260 includes gas inlet 262a and gas inlet 262b. Gas inlet 262a is configured to receive secondary gas (e.g., EGR) from a first source (such as the exemplary EGR passage 108a). Gas inlet 262a is configured to receive secondary gas (e.g., EGR) from a different second source (such as the exemplary EGR passage 108b). In some embodiments, fuel inlet pipes 262a-262b may include threads or other removable attachments (e.g., hoses clamped around flanges) at fuel inlet pipes 262a-262b, gas inlet 222, or any of them to allow the check valve 260 to be mounted and fluidly connected to the remainder of the EGR system of engine system 100.

[0059] In some embodiments, the gas mixer 200 may be fluidly connected to an engine system configured such that secondary (e.g., EGR) gas flows alternately in pulses between gas inlet 262a and gas inlet 262b. For example, gas inlet 262a may be in fluid communication with a first cylinder, gas inlet 262b may be in fluid communication with a different second cylinder, and the first cylinder may be configured to exhaust while the second cylinders are not, and vice versa.

[0060] Check valve 260 also includes valve 264. Valve 264 is configured as a disc valve, having a pivoting valve body. Gas flow through one of gas inlets 262a and 262b pushes the valve body open to allow one gas inlet to flow freely and block the other, thereby preventing backflow from gas inlet 262a to gas inlet 262b, and also preventing backflow from gas inlet 262b to gas inlet 262a. Although valve 264 is a disc valve in the example shown, other forms of backflow prevention valves, such as check valves, can also be used.

[0061] Gas nozzle 220 is configured to provide a high-speed gas path. Secondary gas flow path 226 is aerodynamically efficient to maintain high speed (e.g., from exhaust manifolds 106a-106b). This allows the full total pressure of the secondary gas flow to be achieved (e.g., static pressure plus dynamic pressure due to velocity). The fuel flow through fuel inlet pipes 232a-232b adds additional momentum to the secondary gas flow along secondary gas flow path 226. The secondary gas (e.g., EGR) and fuel combine to form a combined main jet to draw in air flowing along air flow path 205. This contrasts with conventional jet pumps, where air and fuel are combined as the main flow to induce a secondary (e.g., EGR) gas flow. An exemplary advantage of the illustrated example is that the pulsed momentum of the secondary gas along secondary gas flow path 226 accelerates the air drawn in from air inlet 212. In embodiments where the air flow is also pumped at its own high speed, for example by… Figure 1 The exemplary turbine 122, the airflow can also provide a complementary reduction in suction pressure as seen in the gas path, so that both flows can help drive the other flow.

[0062] In some implementations, the gas mixer 200 can improve engine performance. For example, by using fuel and secondary airflow to accelerate, pump, or otherwise promote airflow, less compression work from turbine 122 is required to move the same amount of air. By reducing the amount of work required by turbine 122, the amount of back pressure in exhaust manifolds 106a-106b can be reduced, thereby reducing power losses caused by the pumping work performed by the piston during the exhaust stroke. The gas mixer 200 can enable EGR utilization to reach a high level of around 30%. The use of the gas mixer 200 can bring stoichiometric EGR engines close to lean-feed engines in efficiency, while allowing the use of total wastewater discharge (TWC) and thus near-zero emissions.

[0063] In operation, the gas nozzle 220 and the conical converging section 208a increase the velocity and decrease the air pressure along the air flow path 205 in the gas mixer 200. In response to (e.g., due to) the reduced pressure of the secondary gas jet exiting the gas nozzle 220, air is drawn into the gas mixer 200 along the air flow path 205 through the air inlet 212. The secondary gas is guided along the secondary gas flow path 226 (e.g., from exhaust manifolds 106a and 106b) and eventually reaches a point downstream of the conical converging section 208a. The air flow, secondary gas flow, and fuel flow mix to form a combustion mixture. Passing through the conical converging section 208b, the pressure of the combustion mixture increases, and the velocity of the combustion mixture decreases.

[0064] Figure 3A - Another exemplary gas mixer 300 is shown in 3D. Figure 3A A 3D view is shown. Figure 3B A top view is shown. Figure 3C A side view is shown, and Figure 3D It shows along Figure 3C A half-sectional view taken along section A-A. In some embodiments, the gas mixer 300 may be... Figure 1 Gas mixer 114. Gas mixer 300 includes a gas housing 302 having an outlet 310, an air inlet 312, a gas inlet 322a, and a gas inlet 322b. In some embodiments, the air inlet 312 may be fluidly connected to an intake chamber, such as Figure 1 An exemplary air intake chamber 103.

[0065] Main reference Figure 3DThe gas casing 302 defines a mixing chamber 304 having an airflow path 305a, which is further divided into an airflow path 305b and an airflow path 305c. The mixing chamber 304 is configured with a pair of converging-diverging nozzles 306a and 306b. Nozzle 306a has a conical converging portion 308a and a conical diverging portion 308b, in which the airflow path 305b contracts and expands to an outlet 310. Nozzle 306b has a conical converging portion 308c and a conical diverging portion 308d, in which the airflow path 305c contracts and expands to an outlet 310. In some implementations, outlet 310 may be fluidly connected to the intake manifold, such as Figure 1 An example intake manifold 104.

[0066] Air inlet 312 serves as the inlet for converging-diverging nozzles 306a-306b. Conical converging portions 208a and 308c define a pair of air nozzles for the incoming airflow. Typically, air flows in through air inlet 312 upstream of converging-diverging nozzles 306a and 306b, and gas housing 302 divides airflow path 305a into airflow path 305b and airflow path 305c. Airflow path 305b converges in conical converging portion 308a, diverges in conical diverging portion 308b, and exits through outlet 310, entirely along airflow path 305b. Airflow path 305c converges in conical converging portion 308c, diverges in conical diverging portion 308d, and exits through outlet 310, entirely along airflow path 305c.

[0067] The gas mixer 300 includes a gas nozzle 320a fluidly connected to a gas inlet 322a and a gas nozzle 320b fluidly connected to a gas inlet 322b. The gas inlet 322a is configured to receive a secondary gas flow (e.g., EGR gas) and defines a secondary gas flow path 326a through the gas nozzle 320a. The gas inlet 322b is configured to receive a secondary gas flow and defines a secondary gas flow path 326b through the gas nozzle 320b.

[0068] Gas nozzles 320a and 320b are positioned parallel to and centered within airflow paths 305b and 305c, and are configured to supply secondary gas (e.g., flowing along secondary gas flow paths 326a and 326b) to airflow paths 305b and 305c within converging portions 308a and 308c upstream of the diverging portions 308b and 308d of the converging-diverging nozzles 306a and 306b. The gas nozzles are configured to define a secondary gas flow that is complementary (e.g., cooperative, substantially parallel) to the airflow along airflow paths 305b and 305c.

[0069] Gas nozzles 320a-320b are configured to provide a high-speed gas path. Secondary gas flow paths 326a-326b are aerodynamically efficient to maintain high speeds (e.g., from exhaust manifolds 106a-106b). This allows the full total pressure of the secondary gas flow to be achieved (e.g., static pressure plus dynamic pressure due to velocity). The secondary gas becomes the main jet to draw in air flowing along gas flow paths 305b-305c. An exemplary advantage of the illustrated example is that the pulse momentum of the secondary gas along secondary gas flow paths 326a-326b accelerates the air drawn in from air inlet 312. In some embodiments, the gas mixer 300 can improve engine performance. For example, by using a fuel flow and a secondary gas flow to accelerate, pump, or otherwise promote airflow, less compression work from turbine 122 is required to move the same amount of air.

[0070] In some embodiments, the exemplary gas mixers 200 and 300 described above can improve the ability of the exemplary engine system 100 to use carbon-free fuels with slow combustion, such as ammonia (NH3) or mixed fuels such as hydrogen mixed with natural gas. In some embodiments, the exemplary gas mixers 200 or 300 can be used in dual-fuel configurations such as diesel and anhydrous ammonia, wherein existing engines can be easily retrofitted with the gas mixers 200 or 300 to significantly reduce engine emissions.

[0071] While some embodiments have been described in detail above, other modifications are possible. For example, the processes depicted in the figures do not require the specific order or sequence shown to achieve the desired results. Furthermore, additional steps may be provided from the described processes, or these steps may be omitted, and other components may be added to or removed from the described system. Therefore, other embodiments are within the scope of the following claims.

Claims

1. A gas mixer, comprising: a converging-diverging nozzle including a converging portion and a diverging portion and defining a first gas flow path; an air housing including an air inlet configured to supply air to the first gas flow path upstream of the converging-diverging nozzle; a gas housing defining a second gas flow path and including: a first gas inlet configured to receive a secondary gas and allow the secondary gas to enter the second gas flow path; a second gas inlet configured to receive the secondary gas and allow the secondary gas to enter the second gas flow path; a check valve configured to be pushed into a first configuration by a gas pressure of a gas flow along the first gas inlet to allow the gas flow along the first gas inlet and block a gas backflow from the first gas inlet to the second gas inlet, and configured to be pushed into a second configuration by a gas pressure of a gas flow along the second gas inlet to allow the gas flow along the second gas inlet and block a gas backflow from the second gas inlet to the first gas inlet; and a gas nozzle positioned parallel to and centered within the first gas flow path in the converging portion of the converging-diverging nozzle, the gas nozzle configured to supply the secondary gas to the first gas flow path upstream of the diverging portion.

2. The gas mixer of claim 1, wherein, the first gas inlet is configured to receive exhaust gas from a first cylinder of an engine, and the second gas inlet is configured to receive exhaust gas from a second cylinder of the engine, wherein the first cylinder and the second cylinder alternate providing exhaust gas during operation of the engine.

3. The gas mixer of claim 2, wherein, the first gas inlet is in fluid communication with a first exhaust manifold, and the second gas inlet is in fluid communication with a second exhaust manifold.

4. The gas mixer of claim 1, wherein, a fuel inlet coupled to the gas mixer and including a fuel inlet tube positioned parallel to and centered within the second gas flow path, the fuel inlet tube configured to supply fuel into the second gas flow path upstream of the gas nozzle.

5. The gas mixer of any one of claims 1, 2, and 3, wherein, a fuel inlet coupled to the gas mixer and including a fuel inlet tube positioned parallel to and centered within the second gas flow path, the fuel inlet tube configured to supply fuel into the second gas flow path upstream of the gas nozzle.

6. An engine system, comprising: an intake manifold configured to receive a combustible mixture configured to combust within a first combustion chamber and a second combustion chamber; a throttle located upstream of the intake manifold, the throttle configured to at least partially regulate an air flow into the intake manifold; an exhaust manifold including a first exhaust gas sub-manifold configured to receive combustion products from the first combustion chamber and a second exhaust gas sub-manifold configured to receive combustion products from the second combustion chamber; and a gas mixer coupled to the first exhaust gas sub-manifold and the second exhaust gas sub-manifold, the gas mixer including: a gas mixer downstream of the throttle and upstream of the intake manifold, the gas mixer including: a converging-diverging nozzle including a converging portion and a diverging portion and defining a first gas flow path; an air housing including an air inlet configured to supply air to the first gas flow path upstream of the converging-diverging nozzle; a gas housing defining a second gas flow path and including: a first gas inlet configured to receive a secondary gas from the first exhaust gas sub-manifold and allow the secondary gas to enter the second gas flow path; and a second gas inlet configured to receive the secondary gas from the second exhaust gas sub-manifold and allow the secondary gas to enter the second gas flow path; a check valve configured to be pushed into a first configuration by a gas pressure of a gas flow along the first gas inlet to allow the gas flow along the first gas inlet and block a gas backflow from the first gas inlet to the second gas inlet, and to be pushed into a second configuration by a gas pressure of a gas flow along the second gas inlet to allow the gas flow along the second gas inlet and block a gas backflow from the second gas inlet to the first gas inlet; and a gas nozzle positioned parallel to and centered within the first gas flow path in the converging portion of the converging-diverging nozzle, the gas nozzle configured to supply the secondary gas to the first gas flow path upstream of the diverging portion.

7. The engine system of claim 6, wherein, the first gas inlet is configured to receive exhaust gas recirculation gas from the exhaust manifold.

8. The engine system of claim 6, wherein, the first exhaust gas sub-manifold is configured to receive exhaust gas from a first cylinder of the engine system, and the second exhaust gas sub-manifold is configured to receive exhaust gas from a second cylinder of the engine system, wherein the first cylinder and the second cylinder are configured to provide exhaust gas alternately during operation of the engine system.

9. The engine system of claim 6, wherein, the first exhaust gas sub-manifold is configured to receive exhaust gas from a first cylinder of the engine system, and the second exhaust gas sub-manifold is configured to receive exhaust gas from a second cylinder of the engine system, wherein the first cylinder and the second cylinder are configured to provide exhaust gas alternately during operation of the engine system.

10. The engine system of any one of claims 6, 7, 8, and 9, wherein, a compressor upstream of the throttle, the compressor configured to increase a pressure within the first gas flow path.

11. The engine system of claim 10, wherein, an exhaust gas cooler positioned in a flow path between the exhaust manifold and the gas mixer and configured to decrease a temperature of exhaust gas before the gas mixer.

12. The engine system of claim 10, wherein, The gas mixer further includes a fuel inlet coupled to the gas mixer, including a fuel inlet tube positioned parallel to and centered within the second gas flow path, the fuel inlet tube configured to supply fuel into the second gas flow path upstream of the gas nozzle.

13. The engine system of claim 10, wherein, A turbine is also included downstream of the exhaust manifold, the turbine coupled to the compressor and configured to rotate the compressor.

14. The engine system of claim 13, wherein, An exhaust gas cooler is also included positioned in flow path between the exhaust manifold and the gas mixer and configured to reduce a temperature of exhaust gas prior to the gas mixer.

15. The engine system of claim 13, wherein, The gas mixer further includes a fuel inlet coupled to the gas mixer, including a fuel inlet tube positioned parallel to and centered within the second gas flow path, the fuel inlet tube configured to supply fuel into the second gas flow path upstream of the gas nozzle.

16. The engine system of any one of claims 6, 7, 8, and 9, wherein, An exhaust gas cooler is also included positioned in flow path between the exhaust manifold and the gas mixer and configured to reduce a temperature of exhaust gas prior to the gas mixer.

17. The engine system of claim 16, wherein, The gas mixer further includes a fuel inlet coupled to the gas mixer, including a fuel inlet tube positioned parallel to and centered within the second gas flow path, the fuel inlet tube configured to supply fuel into the second gas flow path upstream of the gas nozzle.

18. The engine system of any one of claims 6, 7, 8, and 9, wherein, The gas mixer further includes a fuel inlet coupled to the gas mixer, including a fuel inlet tube positioned parallel to and centered within the second gas flow path, the fuel inlet tube configured to supply fuel into the second gas flow path upstream of the gas nozzle. The gas mixer further includes a fuel inlet coupled to the gas mixer, including a fuel inlet tube positioned parallel to and centered within the second gas flow path, the fuel inlet tube configured to supply fuel into the second gas flow path upstream of the gas nozzle.

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