Systems and methods for controlling intake manifold temperatures in compression ignition engines

Abstract

Embodiments described herein relate to temperature management in compression ignition engines. In some aspects, a method of operating a compression ignition engine can include moving a volume of air through an intake flow path of the compression engine, the intake flow path including a charge air cooler (CAC) and a CAC bypass. The method further includes moving the volume of air into a combustion chamber via an intake manifold and combusting the volume of fuel in the combustion chamber to form exhaust, the volume of fuel having a cetane number less than about 40. The method further includes moving the exhaust through an exhaust flow path, the exhaust flow path including an exhaust gas recirculation EGR flow path and an uncooled EGR flow path.

Description

SYSTEMS AND METHODS FOR CONTROLLING INTAKE MANIFOLD TEMPERATURES IN COMPRESSION IGNITION ENGINESCross-Reference to Related Applications

[0001] This application claims priority to and the benefit of U.S. Provisional Application No. 63 / 558,271, filed February 27, 2024, and entitled “SYSTEMS AND METHODS FOR CONTROLLING INTAKE MANIFOLD TEMPERATURES IN COMPRESSION IGNITION ENGINES,” the disclosure of which is incorporated by reference herein in its entirety.Technical Field

[0002] Embodiments described herein relate to intake temperature management systems for compression ignition engines.Background

[0003] Burning ethanol, methanol, and other low cetane, small-molecule fuels in a mixing- controlled compression ignition (MCCI) engine requires significantly higher temperature to start combustion than diesel and other readily igniting traditional MCCI fuels. One method to achieve sufficiently high combustion temperatures is to increase the temperature of the incoming gases. Incoming gases are typically air and / or recirculated exhaust and are collectively referred to as ‘charge’ - those gases which are brought in during the engine’s intake stroke. Another method to achieve sufficiently high combustion temperatures is to retain hot gases in the cylinder for the next combustion event. Both methods achieve sufficiently high combustion temperatures by managing in-cylinder temperatures at intake valve closing. However, low-cetane fuels often create excessive cylinder metal temperatures, including valve bridge temperatures when they achieve brake mean effective pressures (BMEP) on par withdiesel fuels. Temperature balancing schemes can be developed to effectively reduce these temperatures.Summary

[0004] Embodiments described herein relate to temperature management in compression ignition engines. In some aspects, a method of operating a compression ignition engine can include moving a volume of air through an intake flow path of the compression engine, the intake flow path including a charge air cooler (CAC) and a CAC bypass. The method further includes moving the volume of air into a combustion chamber via an intake manifold and combusting the volume of fuel in the combustion chamber to form exhaust, the volume of fuel having a cetane number less than about 40. The method further includes moving the exhaust through an exhaust flow path, the exhaust flow path including an exhaust gas recirculation cooled EGR flow path and an uncooled EGR flow path. The method further includes estimating a cylinder wall temperature in the compression ignition and based on the estimated wall temperature, adjusting at least one of a ratio of air flow through the CAC to the air flow through the CAC bypass or a ratio of exhaust flow through the cooled EGR flow path to exhaust flow through the uncooled EGR flow paths. In some embodiments, the method can include adjusting a setting of and intake manifold heater based on the estimated wall temperature. In some embodiments, the method can include adjusting a setting of a radiator based on the estimated wall temperature. In some embodiments, the method can inform other decisions, such as pilot injection timing and quantity.Brief Description of the Drawings

[0005] FIG. 1 is a graph of various engine management schemes that can be employed at different speeds and engine torques.

[0006] FIG. 2 shows example target intake manifold temperature (IMT) during a constant speed load step with a fully warmed engine.

[0007] FIG. 3 shows valve bridge temperatures between two exhaust valve seats as a function ofBMEP.

[0008] FIG. 4 is a block diagram of a compression ignition engine, according to an embodiment.

[0009] FIG. 5 is an illustration of a compression ignition engine, according to an embodiment.

[0010] FIG. 6 is an illustration of a compression ignition engine, according to an embodiment.

[0011] FIG. 7 is a flow diagram of a method of operating a compression ignition engine, according to an embodiment.

[0012] FIG. 8 is a logic schematic of a method of operating a compression ignition engine, according to an embodiment.Detailed Description

[0013] Embodiments described herein include a comprehensive approach that spans both high and low load temperature management, as well as engine warm-up. MCCI engines can be difficult to operate with low cetane fuels, such as ethanol. Specifically, providing enough heat at the start of combustion is difficult, particularly when attempting to initiate ignition with minimal ignition delay. Conversely, heat input should be limited so that the engine internal temperatures do not exceed the structural limits of the internal engine materials. The temperature at the start of combustion can be modulated during operation by changing the temperature in the intake manifold. Various methods are used to vary the IMT. These can include adjusting the setting of a CAC, adjusting EGR cooling, and / or adjusting intake heating.

[0014] A model can be used to set a target IMT based on engine load ranges to achieve stable combustion in an MCCI engine, particularly if the MCCI engine is fueled by a low-cetane fuel. Such a model can achieve stable combustion in the MCCI engine while limiting maximum engine internal metal temperatures. Combinations of CAC, CAC bypass, EGR gas cooling, hot EGR gas, and air-fuel ratio control can be employed to achieve these desired IMTs. The compression ignition engine can transition between operating modes to modulate temperatures between ranges. Embodiments described herein can allow for the use of thermal management techniques to simultaneously allow combustion of low-cetane fuels while limiting internal engine temperatures.

[0015] Examples of thermal management systems used in compression ignition engines can be found in U.S. patent No. 9,903,262 (“the ‘262 patent”), filed Apr. 6, 2015, entitled “STOICHIOMETRIC HIGH-TEMPERATURE DIRECT-INJECTION COMPRESSIONIGNITION ENGINE,” International Patent Application No. PCT / US2020 / 032961 (“the ‘961application”), filed May 14, 2020, entitled “COLD START FOR HIGH-OCTANE FUELS IN A DIESEL ENGINE ARCHITECTURE,” U.S. Patent No. No. 11,428,186 (“the ‘ 186 patent”), filed September 16, 2021, entitled ’’FUEL AGNOSTIC COMPRESSION IGNITION ENGINE,” and U.S. Provisional Patent Application No. 63 / 400,653, filed August 24, 2022 and titled “Intake Temperature Management Systems for Compression Ignition of Small Molecule Fuels,” the disclosures of which are hereby incorporated by reference in their entireties.

[0016] Embodiments described herein include methods for determining how to choose a proper intake manifold temperature for engine conditions for an MCCI engine fueled by a low- cetane fuel. A thermal mass model of the engine can calculate metal and gas temperatures based on run time history. Such a method can deliver a desired intake manifold temperature target to yield a proper tradeoff between combustion stability, engine metal temperatures, engine emissions, and engine performance.

[0017] During low and moderate engine loads, intake temperature management can be used to keep high enough IMTs to promote ignition of low-cetane fuels. At high load and high power density operation, there is sufficient residual thermal energy, hot walls, and hot piston to maintain stable operation at lower IMT’s (e.g., less than about 100 °C, less than about 90 °C, less than about 80 °C, less than about 70 °C, less than about 60 °C, or less than about 50 °C, inclusive of all values and ranges therebetween). Managing intake temperature to a minimum within the stable or flat region of the fuel’s ignition delay curve allows for avoiding elevated metal temperatures (such as exhaust bridge locations) and also allows for high thermal efficiency by avoiding excessive heat transfer losses and easier work extraction from leaner mixtures.

[0018] FIG. 1 shows sample targets for steady-state intake manifold temperature conditions as a function of speed and load. High load regions where metal temperature limits dictate maximum intake cooling and high heat transfer from the engine to the gases provide sufficient intake valve temperature for stable combustion to drive low IMT. Light load regions where combustion stability is the key driver can dictate high IMT. Regions between high load and light load can drive mid-range IMT’s. These regions can require different gas-flow configurations to achieve the desired temperatures. More specifically, the top region with high load would include cold EGR and max CAC, corresponding to an IMT of 50°C-100°C. The next region down includes hot EGR with some CAC and an IMT of about 120 °C. The next lower load region includes hot EGR and a CAC bypass with an IMT of greater than 120 °C. The low load regions include intake heating and valve bypass settings. The 100% curves referto the maximum torque an engine is set up to produce at each engine speed (rpm) - also referred to as a “torque curve.” “MAX CAC” refers to a condition wherein all the intake air is routed through the CAC (i.e., zero bypass).

[0019] For transient conditions, metal temperatures lag as load is increased or decreased. This model drives higher IMT’s during load increase until interior metal temps allow lower IMTs. FIG. 2 depicts a transient operating mode, where the engine begins at light or no load at some engine speed and the fueling is rapidly increased to near full load fueling. At the beginning of the injection event, a high 140 °C IMT is required to keep the combustion stable, but as engine internal temperatures increase, such high intake manifold temperatures are not required for stable combustion. These can include wall temperatures in critical locations in the cylinder, such as valve bridges in the cylinder head, valve heads and piston rims. Therefore, intake manifold temperatures can be decreased to protect the engine while allowing stable combustion. In other words, as average cylinder internal metal temperature rises, target IMT can be decreased (e.g., via manipulation of EGR or CAC routing) to protect the engine and avoid overheating.

[0020] FIG. 3 depicts the increase in valve bridge temperatures as a function of BMEP without model-based IMT control. Valve bridge temperatures exceed diesel full load temperatures at much lower BMEP levels. However, using temperature control schemes described herein can allow for the low cetane fuel engine to match diesel fuel’s BMEP at diesel valve bridge temperatures. In other words, using temperature control methods described herein can reduce the valve bridge temperature to a desired level.

[0021] In the highest, full load operating range, CAC and EGR cooling may combine to provide IMT in the range of 50-100 °C. At full load, metal temperatures climb and may reach a point where structural integrity of components, such as pistons, valves and cylinder heads is compromised. Since the engine internal metal temperatures are high, a much lower IMT is needed to reach the same temperature when the piston is at top-dead-center (TDC) near the start of combustion. The high metal temperatures heat the intake air during the intake stroke, raising temperatures at I VC and high metal temperatures continue to heat the air during the first part of compression and reduce heat transfer to the walls near the end of compression. Also, pressures in the cylinder can affect ignition delay as higher gas density shortens the fuel plume travel during ignition delay.

[0022] This temperature control can be accomplished by adding a cooled EGR loop, adjustable based on engine load, ambient temperature, or other feedback to dial in IMT, by partially cooling the EGR to optimize how much cooling is needed throughout the combustion map, or by minimizing the flow of hot or cool EGR. Alternatively, temperature control can be accomplished via air cooling to below ambient temperature by heat exchange with water or other fluid available, evaporative, and / or other cooling methods. Additionally, increasing airfuel ratio can be combined with CAC and EGR cooling to further reduce the metal temperature.

[0023] In the partial load operating range, charge air cooling and uncooled EGR can combine to provide intake manifold temperature in the range of 120 °C. At partial load, metal temperatures are much less than a full load, so higher intake temperatures are needed to achieve sufficient temperature at TDC near the start of combustion and can be safely further increased to enhance combustion stability. Transition operating ranges also exist, where a portion of the exhaust gas is cooled and a portion uncooled to provide intake temperatures between about 80 °C and about 120 °C to meet metal temperature limits and provide sufficient combustion stability. Alternatively cooled EGR can be combined with partial CAC to achieve the same transition operating range.

[0024] In the light load operating range, CAC bypassing and uncooled EGR can combine to provide IMT’s of at least about 140 °C. At light load, metal temperatures approach coolant temperatures, so higher intake temperatures are required to achieve sufficient temperature at TDC near the start of combustion and can be safely further increased to enhance combustion stability. A transition operating range can be employed where a portion of the charge air is cooled and a portion bypasses the cooler to provide intake temperatures between about 120 °C and about 140 °C or higher. Light load TDC gas temperatures can also be managed to required minimum levels by increasing in-cylinder residual heat from the previous combustion event. When these measures are added, intake manifold temperatures cooler than about 90 °C may be sufficient for stable combustion.

[0025] The following equations are sample equations that may be included in a model to manage temperatures in a compression ignition engine:TempTDC = f (JVC gas temperature + heat gain or loss during compression + heat of compression)Where TempTvc.i is the volume average temperature within the combustion chamber of cylinder number ‘i’ when the piston is at TDC.TempTDC i— f (Tc, Twc, i, TWnCR, TIVCf)Where Tc is coolant temperature;Twc.i is actual cylinder wall temperature of cylinder number ‘i’ (a function of coolant temperature and load percentage);CR is compression ratio;Twnis nominal cylinder wall temperature;Tivc.i is intake port out gas temperature plus heat (minus cooling) from the cylinder walls and residual gases during the intake stroke;Tivc = f(TWc, TportgasOut, Torq%, Tc, TCn, ATRH') * ATRH= Change in temperature from residual heat = f(internal EGR mass fraction, Exhaust port gas out Temperature, intake port gas out temperature (i))Torq% is the percent of full load torque;Ten is the nominal coolant temperature (Tstat setting);Tc is the actual coolant temperature;TportgasOut=Intake port gas out temperature = f(intake port gas in temperature, port heat transfer coefficient, mass flow into cylinder (i) and gas specific heat, coolant temperature); andIntake port gas in temperature = Intake manifold temperature + change in temperature from grid heaters.Instantaneous temperatures are calculated incrementally over time as TWc(t) = TWc(t —wall heat loss to coolant per time), such that sequential firings serve to raise the wall temperature until the net heat flux in equals the net heat flux out of the walls and the wall temperature no longer increases. In other cases, when fuel quantity is low, wall temperatures drop over time as heat flux in is less than heat flux out.

[0026] Embodiments described herein relate to various engine architectures and are not limited to the four-stroke architecture most commonly used in on-road applications. The routing of air and fuel and adjusted thermal management can be applied to two-stroke, four- stroke, six-stroke, opposed piston, free piston, over-expanded (Atkinson or other) and / or rotary (Wankel or other) engine types.

[0027] FIG. 4 is a block diagram of an engine 100 with an intake temperature management system, according to an embodiment. As shown, the engine 100 includes a controller 105, a first flow path 110, a charge air cooler (CAC) 120, valves 125a, 125b, 125c (collectively referred to as valves 125), a second flow path 130, a heater 135, a third flow path 140, an intake manifold 150, combustion chambers 160, and optionally a cooled EGR flow path 170. Dotted lines represent optional physical couplings, while dashed lines represent communicative couplings.

[0028] In use, a volume of intake gas flows through the first flow path 110. From the first flow path 110, the volume of intake gas can either be guided to the CAC 120 and / or the second flow path 130 via the valve 125a and the valve 125b. From the CAC 120, the volume of intake gas can flow through optional valve 125c to the third flow path 140. Also, the volume of intake gas can flow from the second flow path 130 to the third flow path 140. The volume of intake gas then flows to the combustion chambers 160 via the intake manifold 150. The heater 135 can be in contact with the second flow path 130, the third flow path 140, and / or the intake manifold 150.

[0029] In some embodiments, the engine 100 can include a four-stroke engine. In some embodiments, the engine 100 can include a two-stroke engine. In some embodiments, the engine 100 can include a five-stroke engine. In some embodiments, the engine 100 can include a six-stroke engine. In some embodiments, the engine 100 can include a free-piston engine. In some embodiments, the engine 100 can include a free piston engine linear. In some embodiments, engine 100 can include a rotary engine. In some embodiments, the engine 100 can include a Wankel rotary engine.

[0030] The first flow path 110 guides the volume of intake air. The flow path 110 is fluidically coupled to the CAC 120 via the valve 125a and the second flow path 130 via the valve 125b. The valves 125a, 125b can guide the volume of intake air to the CAC 120 and / or the second flow path 130. In some embodiments, the valves 125a, 125b can guide the movement of the volume of intake in various partition ratios between the CAC 120 and the second flow path 130.

[0031] In some embodiments, the volumetric percentage of the volume of intake gas fed to the CAC 120 can be at least about 0%, at least about 5%, at least about 10%, at least about 15%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, atleast about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, or at least about 95%. In some embodiments, the volumetric percentage of the volume of intake gas fed to the CAC 120 can be no more than about 100%, no more than about 95%, no more than about 90%, no more than about 85%, no more than about 80%, no more than about 75%, no more than about 70%, no more than about 65%, no more than about 60%, no more than about 55%, no more than about 50%, no more than about 45%, no more than about 40%, no more than about 35%, no more than about 30%, no more than about 25%, no more than about 20%, no more than about 15%, no more than about 10%, or no more than about 5%. Combinations of the above-referenced volumetric percentages are also possible (e.g., at least about 0% and no more than about 100% or at least about 30% and no more than about 70%), inclusive of all values and ranges therebetween. In some embodiments, the volumetric percentage of the volume of intake gas fed to the CAC 120 can be about 0%, about 5%, about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, or about 100%.

[0032] In some embodiments, the first flow path 110 can include a tube. In some embodiments, the first flow path 110 can be composed of an iron-based alloy, structural steel, stainless steel, an iron-based sintered metal, a cast iron alloy, an aluminum alloy, or any combination thereof. In some embodiments, the first flow path 110 can have a circular cross section. In some embodiments, the first flow path 110 can include an elliptical cross section. In some embodiments, the first flow path 110 can include an irregular-shaped cross section.

[0033] The CAC 120 cools the volume of intake gas as the volume of intake gas enters the CAC 120. In some embodiments, the CAC 120 can include a welded-tube charge-air cooler, a heavy duty welded-tube charge air cooler, a bar-plate charge air cooler, a liquid cooled charge-air cooler, a bar-plate liquid cooled charge-air cooler, a round-tube plate fin liquid cooled charge-air cooler, or any combination thereof.

[0034] The valve 125a regulates the flow of the intake gas between the first flow path 110 and the CAC 120. In some embodiments, the valve 125a can be partially opened to partition intake gas between the CAC 120 and the second flow path 130. In some embodiments, the valve 125a can include a butterfly valve, a ball valve, a solenoid valve, a pneumatic valve, a needle valve, an air actuated axial valve, or any combination thereof. In some embodiments, the valve 125a can be used as a throttle valve.

[0035] The valve 125b regulates movement of the intake gas between the first flow path 110 and the second flow path 130. In some embodiments, the valve 125b can be partially open to partition the flow of intake gas between the CAC 120 and the second flow path 130. In some embodiments, the valve 125b can be used as a throttle valve.

[0036] The second flow path 130 can act as a CAC 120 bypass. The second flow path 130 connects the first flow path 110 and the third flow path 140. In some embodiments, the second flow path 130 can have similar dimensions or diameters to the first flow path 110. In some embodiments, the second flow path 130 can run parallel or approximately parallel to the CAC 120.

[0037] The valve 125c regulates movement of the intake gas between the CAC 120 and the third flow path 140. In some embodiments, the valve 125c can act as a second line of defense to prevent flow of intake gas, after the valve 125a and / or the valve 125b. In some embodiments, the heater 135 can heat gas as it moves between the second flow path 130 and the third flow path 140. In some embodiments, the heater 135 can include a grid heater, a block heater, an intake heater-cartridge system, an external cartridge heater, an intake-heater, a fuel- powered burner, a fuel-powered reactor, a heat exchanger with a hot fluid, a power relay grid heater, or any combination thereof. In some embodiments, the heater 135 can be disposed outside of the second flow path 130 and / or the third flow path 140. In some embodiments, the heater 135 can be disposed inside the second flow path 130 and / or the third flow path 140. In some embodiments, the heater 135 can be in physical contact with the intake manifold 150.

[0038] The third flow path 140 can guide the intake fluid to the intake manifold 150. The third flow path 140 can be fluidically coupled to the second flow path 130. In some embodiments, the third flow path 140 can be fluidically coupled to the CAC 120 or blocked from the CAC via the valve 125c. In some embodiments, the third flow path 140 can have similar dimensions or diameter to the first flow path 110 and / or the second flow path 130.

[0039] The intake manifold 150 partitions the volume of intake gas into sections, which feed to the combustion chambers 160. Combustion of fuel occurs inside the combustion chambers 160. In some embodiments, the combustion chambers 160 can include a collection of cylinders. In some embodiments, the combustion can occur via compression ignition. In some embodiments, the combustion chambers 160 can include an inner surface, a head surface, a piston disposed and configured to move in the engine cylinder, an intake valve, and an exhaust valve (not shown). In some embodiments, the engine 100 can include about 1, about 2, about3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, about 11, about 12, about 13, about 14, about 15, about 16, about 17, about 18, about 19, about 20, about 21, about 22, about 23, about 24, about 25, about 26, about 27, about 28, about 29, about 30, about 31, or about 32 cylinders. In some embodiments, one or more of the combustion chambers 160 can include temperature sensors disposed therein.

[0040] The cooled EGR flow path 170 is optional and diverts a portion of the exhaust from the combustion chambers 160 back through the intake manifold 150 and back into the combustion chambers 160. The cooled EGR flow path 170 aids in maintaining heat in the combustion chambers 160. The cooled EGR flow path 170 can include a series of tubes that recirculate the exhaust. In some embodiments, the cooled EGR flow path 170 can divert at least about 1%, at least about 2%, at least about 3%, at least about 4%, at least about 5%, at least about 6%, at least about 7%, at least about 8%, at least about 9%, at least about 10%, at least about 15%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, or at least about 75% of the exhaust from the combustion chambers 160. In some embodiments, one or more valves (not shown) control the movement and routing of exhaust gas through the cooled EGR flow path 170.

[0041] The controller 105 controls movement of intake gas and exhaust gas through the engine 100. As shown, the controller 105 is in communicative contact with the valves 125 and the cooled EGR flow path 170. In some embodiments, the controller 105 can be operated by a user or operator. In some embodiments, the controller 105 can be operated automatically (e.g., via an algorithm).

[0042] FIG. 5 is an illustration of an engine 200 with an intake temperature management system, according to an embodiment. As shown, the engine 200 includes a first flow path 210, a turbocharger 215, a CAC 220, valves 225a, 225b, 225c, 225d (collectively referred to as valves 225), a second flow path 230, heaters 235a, 235b, 235c (collectively referred to as heaters 235), a third flow path 240, an intake manifold 250, a plurality of combustion chambers 260, a cooled EGR flow path 270, an uncooled EGR flow path 280, and an aftertreatment 290. In some embodiments, the first flow path 210, the CAC 220, the valves 225, the second flow path 230, the heaters 235, the third flow path 240, the intake manifold 250, the plurality of combustion chambers 260, and the cooled EGR flow path 270 can be the same or substantially similar to the first flow path 110, the CAC 120, the valves 125, the second flow path 130, the heaters 135, the third flow path 140, the intake manifold 150, the plurality of combustionchambers 160, and the cooled EGR flow path 170, as described above with reference to FIG. 4. Thus, certain aspects of the first flow path 210, the CAC 220, the valves 225, the second flow path 230, the heaters 235, the third flow path 240, the intake manifold 250, the plurality of combustion chambers 260, and the cooled EGR flow path 270 are not described in greater detail herein. A controller 205 controls various aspects of the engine 200.

[0043] As shown, two connection areas exist between the first flow path 210 and the third flow path 240. One connection area includes the CAC 220 and the other connection area includes the second flow path 230, which bypasses the CAC 220. In some embodiments, these connection points can be optimized aerodynamically.

[0044] In some embodiments, valve 225a can be excluded, depending on noise and flow control considerations. In some embodiments, the valve 225b can be used as a throttle valve. In some embodiments, the valves 225 can be operated such that the bypass valve 225b only opens under engine idle or startup conditions but has a default state of being closed. In some embodiments, the valve 225a can have a default open state, such that it only closes under engine idle or startup conditions.

[0045] As shown, the turbocharger 215 includes an intake gas inlet 216, a turbine 217, and compressor 218. In some embodiments, exhaust gas can flow into the inlet 216 to power the turbine 217. In some embodiments, the exhaust gas can flow from the turbocharger 215 to the aftertreatment 290 and out of the aftertreatment 290 via an outlet 291. The intake gas flows through the first flow path 210 after being pressurized in the turbocharger 215.

[0046] The heaters 235 are located at various points throughout the engine 200. The heater 235a can include an intake grid heater that heats the intake manifold 250 and the combustion chambers 260. In some embodiments, the heater 235b can include a power relay grid heater that heats the intake manifold 250. In some embodiments, the heater 235c can include a power relay grid heater attached to the CAC 220. Packaging space for heating elements is a significant challenge with the use of such heaters. This includes space for the heater itself as well as a means of delivering power to the heater, while placing the heat source close enough to the intake ports of the engine 200, such that heat transfer to the walls of the combustion chambers 260 is reduced after heating the intake gas.

[0047] As shown, the cooled EGR flow path 270 leads back to the intake manifold 250. An EGR valve 275 regulates the flow of exhaust gas. In some embodiments, the cooled EGR flow path 270 can include tubing. In some embodiments, the cooled EGR flow path 270 can havea smaller diameter than the first flow path 210, the second flow path 230, and / or the third flow path. In some embodiments, the cooled EGR flow path 270 can have a diameter the same or substantially similar to the first flow path 210, the second flow path 230, and / or the third flow path.

[0048] The cooled EGR flow path 270 allows the flow of exhaust gas from the combustion chambers 260 back to the intake manifold 250 via the EGR flow path valve 275. As shown, the cooled EGR flow path 270 includes an EGR cooler 276. The EGR cooler 276 can aid in cooling the gas circulated through the cooled EGR flow path 270. In some embodiments, the EGR cooler 276 can include a welded-tube heat exchanger, a heavy duty welded-tube heat exchanger, a bar-plate heat exchanger, a liquid cooled heat exchanger, a bar-plate liquid cooled heat exchanger, a round-tube plate fin liquid cooled heat exchanger, or any combination thereof.

[0049] The uncooled EGR flow path 280 allows for the flow of intake gas from the combustion chambers 260 back to the intake manifold 250 without passing through a cooler. The valve 225d regulates the flow of gas through the uncooled EGR flow path 280. The aftertreatment 290 can remove harmful emissions from the exhaust. In some embodiments, the aftertreatment 290 can include a catalytic converter. In some embodiments, the aftertreatment 290 can include one or more sensors.

[0050] As shown, the controller 205 is communicatively coupled to the valves 225 and the EGR valve 275. The controller 205 can guide the flow of air and / or fuel through the engine 200. In some embodiments, the controller 205 can generate instructions for opening and closing of the valves 225 and the EGR valve 275 based on a measured IMT. For example, if the measured IMT is greater than a desired setpoint, the controller 205 can increase the amount the valve 225a is open while decreasing the amount the valve 225b is open in order to divert more intake air through the CAC 220. As another example, if the measured IMT is greater than a desired setpoint, the EGR valve 275 can be opened more, while the valve 225d can be opened less in order to pass more exhaust through the EGR cooler 276.

[0051] FIG. 6 is an illustration of an engine 300 with an intake temperature management system, according to an embodiment. As shown, the engine 300 includes a controller 305, a first flow path 310, a turbocharger 315 with an intake gas inlet 316, a turbine 317, and a compressor 318, a CAC 320, valves 325a, 325b, 325c, 325d, 325e, 325f (collectively referred to as valves 325), a sub-cooled air cooler 322, a second flow path 330, heaters 335a, 335b,335c (collectively referred to as heaters 335), a third flow path 340, an intake manifold 350, a plurality of combustion chambers 360, a cooled EGR flow path 370, an uncooled EGR flow path 380, and an aftertreatment 390 with an outlet 391. In some embodiments, the controller 305, the first flow path 310, the turbocharger 315, the intake gas inlet 316, the turbine 317, the compressor 318, the CAC 320, the valves 325, the second flow path 330, the heaters 335, the third flow path 340, the intake manifold 350, the plurality of combustion chambers 360, the cooled EGR flow path 370, the uncooled EGR flow path 380, the aftertreatment 390, and the outlet 391 can be the same or substantially similar to the controller 205, the first flow path 210, the turbocharger 215, the intake gas inlet 216, the turbine 217, the compressor 218, the CAC 220, the valves 225, the second flow path 230, the heaters 235, the third flow path 240, the intake manifold 250, the plurality of combustion chambers 260, the cooled EGR flow path 270, the uncooled EGR flow path 280, the aftertreatment 290, and the outlet 291 , as described above with reference to FIG. 5. Thus, certain aspects of the controller 305, first flow path 310, the turbocharger 315, the intake gas inlet 316, the turbine 317, the compressor 318, the CAC 320, the valves 325, the second flow path 330, the heaters 335, the third flow path 340, the intake manifold 350, the plurality of combustion chambers 360, the cooled EGR flow path 370, the uncooled EGR flow path 380, the aftertreatment 390, and the outlet 391 are not described in greater detail herein.

[0052] As shown, the engine 300 includes a grid heater controller 335d that controls the grid heaters 335b. The sub-cooled air cooler 322 allows an additional pathway for intake gas to become cooled. The valve 325f controls flow of intake gas into the sub-cooled air cooler 322. In some embodiments, the sub-cooled air cooler 322 can draw even more heat from the intake gas than the CAC 320. The partitioning of the intake gas between the second flow path 330, the CAC 320, and the sub-cooled air cooler 322 can be tuned based on the setpoint IMT and the actual IMT.

[0053] FIG. 7 is a flow diagram of a method 10 of operating a compression ignition engine. As shown, the method 10 includes moving a volume of intake gas through an intake flow path of a compression ignition engine at step 11, moving the volume of intake gas into the combustion chambers via the intake manifold at step 12, combusting a volume of fuel in the combustion chamber to form exhaust at step 13, moving the exhaust through the exhaust flow path including a cooled EGR flow path and an uncooled EGR flow path at step 14, estimating a cylinder wall temperature in the compression ignition engine at step 15, and adjusting one ormore engine parameters based on the cylinder wall temperature and the TDC gas temperature at step 16.

[0054] Step 11 includes moving a volume of intake gas through the intake flow path of the compression ignition engine. In some embodiments, the intake gas can include air. In some embodiments, the intake gas can include air. In some embodiments, the intake gas can include ambient air. In some embodiments, the intake gas can have an oxygen content of at least about 5 vol%, at least about 10 vol%, at least about 15 vol%, at least about 20 vol%, at least about 25 vol%, at least about 30 vol%, at least about 35 vol%, at least about 40 vol%, or at least about 45 vol%. In some embodiments, the intake gas can have an oxygen content of no more than about 50 vol%, no more than about 45 vol%, no more than about 40 vol%, no more than about 35 vol%, no more than about 30 vol%, no more than about 25 vol%, no more than about 20 vol%, no more than about 15 vol%, or no more than about 10 vol%. Combinations of the above-referenced oxygen contents are also possible (e.g., at least about 5 vol% and no more than about 50 vol% or at least about 20 vol% and no more than about 30 vol%), inclusive of all values and ranges therebetween. In some embodiments, the intake gas can have an oxygen content of about 5 vol%, about 10 vol%, about 15 vol%, about 20 vol%, about 25 vol%, about 30 vol%, about 35 vol%, about 40 vol%, about 45 vol%, or about 50 vol%.

[0055] In some embodiments, the intake flow path can include a CAC, a sub-cooled air cooler, a CAC bypass, or any combination thereof. In some embodiments, the intake flow path can include a turbo-compounding device. In some embodiments, the intake flow path can include a turbocharger. In some embodiments, the intake flow path can include a supercharger. The intake flow path includes valves that direct the flow of the intake gas between the various flow paths.

[0056] In some embodiments, the volume of intake gas can be fed through the intake flow path at a pressure of at least about 0.01 bar (gauge), at least about 0.02 bar, at least about 0.03 bar, at least about 0.04 bar, at least about 0.05 bar, at least about 0.06 bar, at least about 0.07 bar, at least about 0.08 bar, at least about 0.09 bar, at least about 0.1 bar, at least about 0.2 bar, at least about 0.3 bar, at least about 0.4 bar, at least about 0.5 bar, at least about 0.6 bar, at least about 0.7 bar, at least about 0.8 bar, at least about 0.9 bar, at least about 1 bar, at least about 2 bar, at least about 3 bar, at least about 4 bar, at least about 5 bar, at least about 6 bar, at least about 7 bar, at least about 8 bar, at least about 9 bar, at least about 10 bar, at least about 20 bar, at least about 30 bar, at least about 40 bar, at least about 50 bar, at least about 60 bar, at least about 70 bar, at least about 80 bar, at least about 90 bar, at least about 100 bar, at least about110 bar, at least about 120 bar, at least about 130 bar, at least about 140 bar, at least about 150 bar, at least about 160 bar, at least about 170 bar, at least about 180 bar, or at least about 190 bar. In some embodiments, the volume of intake gas can be fed at a pressure of no more than about 200 bar, no more than about 190 bar, no more than about 180 bar, no more than about 170 bar, no more than about 160 bar, no more than about 150 bar, no more than about 140 bar, no more than about 130 bar, no more than about 120 bar, no more than about 110 bar, no more than about 100 bar, no more than about 90 bar, no more than about 80 bar, no more than about 70 bar, no more than about 60 bar, no more than about 50 bar, no more than about 40 bar, no more than about 30 bar, no more than about 20 bar, no more than about 10 bar, no more than about 9 bar, no more than about 8 bar, no more than about 7 bar, no more than about 6 bar, no more than about 5 bar, no more than about 4 bar, no more than about 3 bar, no more than about 2 bar, no more than about 1 bar, no more than about 0.9 bar, no more than about 0.8 bar, no more than about 0.7 bar, no more than about 0.6 bar, no more than about 0.5 bar, no more than about 0.4 bar, no more than about 0.3 bar, no more than about 0.2 bar, no more than about 0.1 bar, no more than about 0.09 bar, no more than about 0.08 bar, no more than about 0.07 bar, no more than about 0.06 bar, no more than about 0.05 bar, no more than about 0.04 bar, no more than about 0.03 bar, or no more than about 0.02 bar. Combinations of the abovereferenced pressures are also possible (e.g., at least about 0.01 bar and no more than about 200 bar or at least about 2 bar and no more than about 100 bar, inclusive of all values and ranges therebetween. In some embodiments, the first flow path at a pressure of about 0.01 bar, about 0.02 bar, about 0.03 bar, about 0.04 bar, about 0.05 bar, about 0.06 bar, about 0.07 bar, about 0.08 bar, about 0.09 bar, about 0.1 bar, about 0.2 bar, about 0.3 bar, about 0.4 bar, about 0.5 bar, about 0.6 bar, about 0.7 bar, about 0.8 bar, about 0.9 bar, about 1 bar, about 2 bar, about 3 bar, about 4 bar, about 5 bar, about 6 bar, about 7 bar, about 8 bar, about 9 bar, about 10 bar, about 20 bar, about 30 bar, about 40 bar, about 50 bar, about 60 bar, about 70 bar, about 80 bar, about 90 bar, about 100 bar, about 110 bar, about 120 bar, about 130 bar, about 140 bar, about 150 bar, about 160 bar, about 170 bar, about 180 bar, about 190 bar, or about 200 bar.

[0057] Step 11 can include partitioning the intake gas through a CAC, a CAC bypass, and / or a sub-cooled air cooler. In some embodiments, at least about 0 vol%, at least about 5 vol%, at least about 10 vol%, at least about 15 vol%, at least about 20 vol%, at least about 25 vol%, at least about 30 vol%, at least about 35 vol%, at least about 40 vol%, at least about 45 vol%, at least about 50 vol%, at least about 55 vol%, at least about 60 vol%, at least about 65 vol%, at least about 70 vol%, at least about 75 vol%, at least about 80 vol%, at least about 85 vol%, atleast about 90 vol%, at least about 95 vol%, at least about 96 vol%, at least about 97 vol%, at least about 98 vol%, or at least about 99 vol% of the intake gas can pass through the CAC. In some embodiments, no more than about 100 vol%, no more than about 99 vol%, no more than about 98 vol%, no more than about 97 vol%, no more than about 96 vol%, no more than about 95 vol%, no more than about 90 vol%, no more than about 85 vol%, no more than about 80 vol%, no more than about 75 vol%, no more than about 70 vol%, no more than about 65 vol%, no more than about 60 vol%, no more than about 55 vol%, no more than about 50 vol%, no more than about 45 vol%, no more than about 40 vol%, no more than about 35 vol%, no more than about 30 vol%, no more than about 25 vol%, no more than about 20 vol%, no more than about 15 vol%, no more than about 10 vol%, or no more than about 5 vol% of the intake gas can pass through the CAC. Combinations of the above-referenced percentages are also possible (e.g., at least about 0 vol% and no more than about 100 vol% or at least about 30 vol% and no more than about 80 vol%), inclusive of all values and ranges therebetween. In some embodiments, about 0 vol%, about 5 vol%, about 10 vol%, about 15 vol%, about 20 vol%, about 25 vol%, about 30 vol%, about 35 vol%, about 40 vol%, about 45 vol%, about 50 vol%, about 55 vol%, about 60 vol%, about 65 vol%, about 70 vol%, about 75 vol%, about 80 vol%, about 85 vol%, about 90 vol%, about 95 vol%, about 96 vol%, about 97 vol%, about 98 vol%, about 99 vol%, or about 100 vol% of the intake gas can pass through the CAC.

[0058] In some embodiments, at least about 0 vol%, at least about 5 vol%, at least about 10 vol%, at least about 15 vol%, at least about 20 vol%, at least about 25 vol%, at least about 30 vol%, at least about 35 vol%, at least about 40 vol%, at least about 45 vol%, at least about 50 vol%, at least about 55 vol%, at least about 60 vol%, at least about 65 vol%, at least about 70 vol%, at least about 75 vol%, at least about 80 vol%, at least about 85 vol%, at least about 90 vol%, at least about 95 vol%, at least about 96 vol%, at least about 97 vol%, at least about 98 vol%, or at least about 99 vol% of the intake gas can pass through the CAC bypass. In some embodiments, no more than about 100 vol%, no more than about 99 vol%, no more than about 98 vol%, no more than about 97 vol%, no more than about 96 vol%, no more than about 95 vol%, no more than about 90 vol%, no more than about 85 vol%, no more than about 80 vol%, no more than about 75 vol%, no more than about 70 vol%, no more than about 65 vol%, no more than about 60 vol%, no more than about 55 vol%, no more than about 50 vol%, no more than about 45 vol%, no more than about 40 vol%, no more than about 35 vol%, no more than about 30 vol%, no more than about 25 vol%, no more than about 20 vol%, no more than about 15 vol%, no more than about 10 vol%, or no more than about 5 vol% of the intake gas can passthrough the CAC bypass. Combinations of the above-referenced percentages are also possible (e.g., at least about 0 vol% and no more than about 100 vol% or at least about 30 vol% and no more than about 80 vol%), inclusive of all values and ranges therebetween. In some embodiments, about 0 vol%, about 5 vol%, about 10 vol%, about 15 vol%, about 20 vol%, about 25 vol%, about 30 vol%, about 35 vol%, about 40 vol%, about 45 vol%, about 50 vol%, about 55 vol%, about 60 vol%, about 65 vol%, about 70 vol%, about 75 vol%, about 80 vol%, about 85 vol%, about 90 vol%, about 95 vol%, about 96 vol%, about 97 vol%, about 98 vol%, about 99 vol%, or about 100 vol% of the intake gas can pass through the CAC bypass.

[0059] In some embodiments, at least about 0 vol%, at least about 5 vol%, at least about 10 vol%, at least about 15 vol%, at least about 20 vol%, at least about 25 vol%, at least about 30 vol%, at least about 35 vol%, at least about 40 vol%, at least about 45 vol%, at least about 50 vol%, at least about 55 vol%, at least about 60 vol%, at least about 65 vol%, at least about 70 vol%, at least about 75 vol%, at least about 80 vol%, at least about 85 vol%, at least about 90 vol%, at least about 95 vol%, at least about 96 vol%, at least about 97 vol%, at least about 98 vol%, or at least about 99 vol% of the intake gas can pass through the sub-cooled air cooler. In some embodiments, no more than about 100 vol%, no more than about 99 vol%, no more than about 98 vol%, no more than about 97 vol%, no more than about 96 vol%, no more than about 95 vol%, no more than about 90 vol%, no more than about 85 vol%, no more than about 80 vol%, no more than about 75 vol%, no more than about 70 vol%, no more than about 65 vol%, no more than about 60 vol%, no more than about 55 vol%, no more than about 50 vol%, no more than about 45 vol%, no more than about 40 vol%, no more than about 35 vol%, no more than about 30 vol%, no more than about 25 vol%, no more than about 20 vol%, no more than about 15 vol%, no more than about 10 vol%, or no more than about 5 vol% of the intake gas can pass through the sub-cooled air cooler. Combinations of the above-referenced percentages are also possible (e.g., at least about 0 vol% and no more than about 100 vol% or at least about 30 vol% and no more than about 80 vol%), inclusive of all values and ranges therebetween. In some embodiments, about 0 vol%, about 5 vol%, about 10 vol%, about 15 vol%, about 20 vol%, about 25 vol%, about 30 vol%, about 35 vol%, about 40 vol%, about 45 vol%, about 50 vol%, about 55 vol%, about 60 vol%, about 65 vol%, about 70 vol%, about 75 vol%, about 80 vol%, about 85 vol%, about 90 vol%, about 95 vol%, about 96 vol%, about 97 vol%, about 98 vol%, about 99 vol%, or about 100 vol% of the intake gas can pass through the sub-cooled air cooler.

[0060] Step 12 includes moving the volume of the intake gas into the combustion chambers via the intake manifold. The intake manifold divides a single flow stream into multiple flow streams, such that the intake gas flows into multiple combustion chambers. In some embodiments, the intake manifold can divide the flow stream into about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, about 11, about 12, about 13, about 14, about 15, about 16, about 17, about 18, about 19, about 20, about 21, about 22, about 23, about 24, about 25, about 26, about 27, about 28, about 29, about 30, about 31, or about 32 flow streams and combustion chambers, inclusive of all values and ranges therebetween. In some embodiments, the intake manifold can include a temperature sensor disposed therein for IMT measurement.

[0061] In some embodiments, the volume of intake gas can enter the combustion chambers at a pressure of at least about 0.01 bar (gauge), at least about 0.02 bar, at least about 0.03 bar, at least about 0.04 bar, at least about 0.05 bar, at least about 0.06 bar, at least about 0.07 bar, at least about 0.08 bar, at least about 0.09 bar, at least about 0.1 bar, at least about 0.2 bar, at least about 0.3 bar, at least about 0.4 bar, at least about 0.5 bar, at least about 0.6 bar, at least about 0.7 bar, at least about 0.8 bar, at least about 0.9 bar, at least about 1 bar, at least about 2 bar, at least about 3 bar, at least about 4 bar, at least about 5 bar, at least about 6 bar, at least about 7 bar, at least about 8 bar, at least about 9 bar, at least about 10 bar, at least about 20 bar, at least about 30 bar, at least about 40 bar, at least about 50 bar, at least about 60 bar, at least about 70 bar, at least about 80 bar, at least about 90 bar, at least about 100 bar, at least about 110 bar, at least about 120 bar, at least about 130 bar, at least about 140 bar, at least about 150 bar, at least about 160 bar, at least about 170 bar, at least about 180 bar, or at least about 190 bar. In some embodiments, the volume of intake gas can enter the combustion chambers at a pressure of no more than about 200 bar, no more than about 190 bar, no more than about 180 bar, no more than about 170 bar, no more than about 160 bar, no more than about 150 bar, no more than about 140 bar, no more than about 130 bar, no more than about 120 bar, no more than about 110 bar, no more than about 100 bar, no more than about 90 bar, no more than about 80 bar, no more than about 70 bar, no more than about 60 bar, no more than about 50 bar, no more than about 40 bar, no more than about 30 bar, no more than about 20 bar, no more than about 10 bar, no more than about 9 bar, no more than about 8 bar, no more than about 7 bar, no more than about 6 bar, no more than about 5 bar, no more than about 4 bar, no more than about 3 bar, no more than about 2 bar, no more than about 1 bar, no more than about 0.9 bar, no more than about 0.8 bar, no more than about 0.7 bar, no more than about 0.6 bar, no more than about0.5 bar, no more than about 0.4 bar, no more than about 0.3 bar, no more than about 0.2 bar, no more than about 0.1 bar, no more than about 0.09 bar, no more than about 0.08 bar, no more than about 0.07 bar, no more than about 0.06 bar, no more than about 0.05 bar, no more than about 0.04 bar, no more than about 0.03 bar, or no more than about 0.02 bar. Combinations of the above-referenced pressures are also possible (e.g., at least about 0.01 bar and no more than about 200 bar or at least about 2 bar and no more than about 100 bar, inclusive of all values and ranges therebetween. In some embodiments, the volume of the intake gas can enter the combustion chambers at a pressure of about 0.01 bar, about 0.02 bar, about 0.03 bar, about 0.04 bar, about 0.05 bar, about 0.06 bar, about 0.07 bar, about 0.08 bar, about 0.09 bar, about 0.1 bar, about 0.2 bar, about 0.3 bar, about 0.4 bar, about 0.5 bar, about 0.6 bar, about 0.7 bar, about 0.8 bar, about 0.9 bar, about 1 bar, about 2 bar, about 3 bar, about 4 bar, about 5 bar, about 6 bar, about 7 bar, about 8 bar, about 9 bar, about 10 bar, about 20 bar, about 30 bar, about 40 bar, about 50 bar, about 60 bar, about 70 bar, about 80 bar, about 90 bar, about 100 bar, about 110 bar, about 120 bar, about 130 bar, about 140 bar, about 150 bar, about 160 bar, about 170 bar, about 180 bar, about 190 bar, or about 200 bar.

[0062] In some embodiments, the intake manifold can include an intake manifold heater. In some embodiments, the intake manifold heater can be toggled based on an estimated TDC temperature and estimated cylinder wall temperature. In some embodiments, the method 10 can include measuring and / or monitoring the intake manifold temperature. In some embodiments, the intake manifold temperature can refer to a temperature at a specific point in the intake manifold (e.g., at a point sufficiently downstream of EGR gas introduction such that the temperature is representative of the gas temperature going to each cylinder, or at multiple spatially separator points to ascertain the temperature of gas going into individual cylinders or groups of cylinders). In some embodiments, the intake manifold temperature can be measured as a volume-average intake manifold temperature. In some embodiments, the measured intake manifold temperature can be at least about -50 °C, at least about -40 °C, at least about -30 °C, at least about -20 °C, at least about -10 °C, at least about 0 °C, at least about 10 °C, at least about 20 °C, at least about 30 °C, at least about 40 °C, at least about 50 °C, at least about 60 °C, at least about 70 °C, at least about 80 °C, at least about 90 °C, at least about 100 °C, at least about 110 °C, at least about 120 °C, at least about 130 °C, at least about 140 °C, at least about 150 °C, at least about 160 °C, at least about 170 °C, at least about 180 °C, or at least about 190 °C. In some embodiments, the measured intake manifold temperature can be no more than about 200 °C, no more than about 190 °C, no more than about 180 °C, no more than about 170°C, no more than about 160 °C, no more than about 150 °C, no more than about 140 °C, no more than about 130 °C, no more than about 120 °C, no more than about 110 °C, no more than about 100 °C, no more than about 90 °C, no more than about 80 °C, no more than about 70 °C, no more than about 60 °C, no more than about 50 °C, no more than about 40 °C, no more than about 30 °C, no more than about 20 °C, no more than about 10 °C, no more than about 0 °C, no more than about -10 °C, no more than about -20 °C, no more than about -30 °C, or no more than about -40 °C. Combinations of the above-referenced temperatures are also possible (e.g., at least about -50 °C and no more than about 200 °C or at least about 50 °C and no more than about 150 °C), inclusive of all values and ranges therebetween. In some embodiments, the measured intake manifold temperature can be about -50 °C, about -40 °C, about -30 °C, about -20 °C, about -10 °C, about 0 °C, about 10 °C, about 20 °C, about 30 °C, about 40 °C, about 50 °C, about 60 °C, about 70 °C, about 80 °C, about 90 °C, about 100 °C, about 110 °C, about 120 °C, about 130 °C, about 140 °C, about 150 °C, about 160 °C, about 170 °C, about 180 °C, about 190 °C, or about 200 °C.

[0063] Step 13 includes combusting a volume of fuel in the combustion chamber to form the exhaust. The fuel is injected into the combustion chamber, where it mixes with the intake gas and combusts via compression ignition. In some embodiments, the fuel can be injected at a pressure of at least about 100 bar (gauge), at least about 200 bar, at least about 300 bar, at least about 400 bar, at least about 500 bar, at least about 600 bar, at least about 700 bar, at least about 800 bar, at least about 900 bar, at least about 1,000 bar, at least about 1,100 bar, at least about 1,200 bar, at least about 1,300 bar, at least about 1,400 bar, at least about 1,500 bar, at least about 1,600 bar, at least about 1,700 bar, at least about 1,800 bar, at least about 1,900 bar, at least about 2,000 bar, at least about 2,100 bar, at least about 2,200 bar, at least about 2,300 bar, at least about 2,400 bar, at least about 2,500 bar, at least about 2,600 bar, at least about 2,700 bar, at least about 2,800 bar, or at least about 2,900 bar,. In some embodiments, the fuel can be injected at a pressure of no more than about 3,000 bar, no more than about 2,900 bar, no more than about 2,800 bar, no more than about 2,700 bar, no more than about 2,600 bar, no more than about 2,500 bar, no more than about 2,400 bar, no more than about 2,300 bar, no more than about 2,200 bar, no more than about 2,100 bar, no more than about 2,000 bar, no more than about 1,900 bar, no more than about 1,800 bar, no more than about 1,700 bar, no more than about 1,600 bar, no more than about 1,500 bar, no more than about 1,400 bar, no more than about 1,300 bar, no more than about 1,200 bar, no more than about 1,100 bar, no more than about 1,000 bar, no more than about 900 bar, no more than about 800 bar, no morethan about 700 bar, no more than about 600 bar, no more than about 500 bar, no more than about 400 bar, no more than about 300 bar, or no more than about 200 bar. Combinations of the above-referenced pressures are also possible (e.g., at least about 100 bar and no more than about 1,500 bar or at least about 500 bar and no more than about 1,000 bar), inclusive of all values and ranges therebetween. In some embodiments, the fuel can be injected at a pressure of about 100 bar, about 200 bar, about 300 bar, about 400 bar, about 500 bar, about 600 bar, about 700 bar, about 800 bar, about 900 bar, about 1,000 bar, about 1,100 bar, about 1,200 bar, about 1,300 bar, about 1,400 bar, about 1,500 bar, about 1,600 bar, about 1,700 bar, about 1,800 bar, about 1,900 bar, about 2,000 bar, about 2,100 bar, about 2,200 bar, about 2,300 bar, about 2,400 bar, about 2,500 bar, about 2,600 bar, about 2,700 bar, about 2,800 bar, about 2,900 bar, or about 3,000 bar.

[0064] In some embodiments, the fuel can include a low-cetane fuel. In some embodiments, the fuel can have a cetane number of at least about -10, at least about -5, at least about 0, at least about 5, at least about 10, at least about 15, at least about 20, at least about 25, at least about 30, or at least about 35. In some embodiments, the fuel can have a cetane number of no more than about 40, no more than about 35, no more than about 30, no more than about 25, no more than about 20, no more than about 15, no more than about 10, no more than about 5, no more than about 0, or no more than about -5. Combinations of the above-referenced cetane numbers of the fuel are also possible (e.g., at least about -10 and no more than about 40 or at least about 10 and no more than about 20), inclusive of all values and ranges therebetween. In some embodiments, the fuel can have a cetane number of about -10, about -5, about 0, about 5, about 10, about 15, about 20, about 25, about 30, about 35, or about 40.

[0065] In some embodiments, the fuel can include naphtha, alcohol, butanol, propanol, ethanol, methanol, a methanol / ethanol mixture, a denatured alcohol, hydrous alcohol, gaseous hydrocarbons, natural gas, methane, ethane, propane, butane, hexane, alternative fuels, hydrogen, ammonia, syngas, and / or CO. In some embodiments, the fuel can include gasoline, a gasoline / ethanol mixture, and / or gasoline / methanol mixture. In some embodiments, the fuel can have a low amount of additives that result in a substantial change in cetane number. In some embodiments, the fuel can include less than about 5,000 ppm, less than about 4,000 ppm, less than about 3,000 ppm, less than about 2,000 ppm, less than about 1,000 ppm, less than about 900 ppm, less than about 800 ppm, less than about 700 ppm, less than about 600 ppm, or less than about 500 ppm by weight of additives that result in a substantial change in cetanenumber. In some embodiments, the fuel can be substantially free of additives that result in a substantial change in cetane number.

[0066] In some embodiments, the fuel can have an octane number (i.e., calculated via (R0N+M0N) / 2 method) of at least about 50, at least about 55, at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, at least about 90, at least about 95, at least about 100, at least about 105, at least about 110, at least about 115, at least about 120, at least about 125, at least about 130, at least about 135, at least about 140, or at least about 145. In some embodiments, the fuel can have an octane number of no more than about 150, no more than about 145, no more than about 140, no more than about 135, no more than about 130, no more than about 125, no more than about 120, no more than about 115, no more than about 110, no more than about 105, no more than about 100, no more than about 95, no more than about 90, no more than about 85, no more than about 80, no more than about 75, no more than about 70, no more than about 65, no more than about 60, or no more than about 55. Combinations of the above-referenced octane numbers are also possible (e.g., at least about 50 and no more than about 150 or at least about 80 and no more than about 120, inclusive of all values and ranges therebetween. In some embodiments, the fuel can have an octane number of about 50, about 55, about 60, about 65, about 70, about 75, about 80, about 85, about 90, about 95, about 100, about 105, about 110, about 115, about 120, about 125, about 130, about 135, about 140, about 145, or about 150.

[0067] In some embodiments, the fuel can include a fuel with 1 carbon atom per molecule (e.g., methane, methanol). In some embodiments, the fuel can be free of carbon atoms (e.g., hydrogen). In some embodiments, the fuel can include a fuel with at least about 1 carbon atom per molecule, at least about 2 carbon atoms per molecule, at least about 3 carbon atoms per molecule, at least about 4 carbon atoms per molecule, at least about 5 carbon atoms per molecule, at least about 6 carbon atoms per molecule, at least about 7 carbon atoms per molecule, at least about 8 carbon atoms per molecule, or at least about 9 carbon atoms per molecule. In some embodiments, the fuel can include a fuel with no more than about 10 carbon atoms per molecule, no more than about 9 carbon atoms per molecule, no more than about 8 carbon atoms per molecule, no more than about 7 carbon atoms per molecule, no more than about 6 carbon atoms per molecule, no more than about 5 carbon atoms per molecule, no more than about 4 carbon atoms per molecule, no more than about 3 carbon atoms per molecule, or no more than about 2 carbon atoms per molecule. Combinations of the above-referenced numbers of carbon atoms per molecule are also possible (e.g., at least about 1 carbon atom permolecule and no more than about 10 carbon atoms per molecule or at least about 1 carbon atom per molecule and no more than about 3 carbon atoms per molecule), inclusive of all values and ranges therebetween. In some embodiments, the fuel can include a fuel with about 1 carbon atom per molecule, about 2 carbon atoms per molecule, about 3 carbon atoms per molecule, about 4 carbon atoms per molecule, about 5 carbon atoms per molecule, about 6 carbon atoms per molecule, about 7 carbon atoms per molecule, about 8 carbon atoms per molecule, about 9 carbon atoms per molecule, or about 10 carbon atoms per molecule.

[0068] In some embodiments, the fuel can include water (i.e., the fuel can be hydrous). In some embodiments, the fuel can include at least about 0.1 wt%, at least about 0.2 wt%, at least about 0.3 wt%, at least about 0.4 wt%, at least about 0.5 wt%, at least about 0.6 wt%, at least about 0.7 wt%, at least about 0.8 wt%, at least about 0.9 wt%, at least about 1 wt%, at least about 2 wt%, at least about 3 wt%, at least about 4 wt%, at least about 5 wt%, at least about 6 wt%, at least about 7 wt%, at least about 8 wt%, at least about 9 wt%, at least about 10 wt%, at least about 11 wt%, at least about 12 wt%, at least about 13 wt%, or at least about 14 wt% water. In some embodiments, the fuel can include no more than about 15 wt%, no more than about 14 wt%, no more than about 13 wt%, no more than about 12 wt%, no more than about 11 wt%, no more than about 10 wt%, no more than about 9 wt%, no more than about 8 wt%, no more than about 7 wt%, no more than about 6 wt%, no more than about 5 wt%, no more than about 4 wt%, no more than about 3 wt%, no more than about 2 wt%, no more than about 1 wt%, no more than about 0.9 wt%, no more than about 0.8 wt%, no more than about 0.7 wt%, no more than about 0.6 wt%, no more than about 0.5 wt%, no more than about 0.4 wt%, no more than about 0.3 wt%, or no more than about 0.2 wt% water. Combinations of the abovereferenced water percentages are also possible (e.g., at least about 0.1 wt% and no more than about 15 wt% or at least about 0.5 wt% and no more than about 10 wt%), inclusive of all values and ranges therebetween. In some embodiments, the fuel can include about 0.1 wt%, about 0.2 wt%, about 0.3 wt%, about 0.4 wt%, about 0.5 wt%, about 0.6 wt%, about 0.7 wt%, about 0.8 wt%, about 0.9 wt%, about 1 wt%, about 2 wt%, about 3 wt%, about 4 wt%, about 5 wt%, about 6 wt%, about 7 wt%, about 8 wt%, about 9 wt%, about 10 wt%, about 11 wt%, about 12 wt%, about 13 wt%, about 14 wt%, or about 15 wt% water.

[0069] In some embodiments, the fuel can be mixed with the volume of intake gas in a lean mixture ratio, a rich mixture ratio, or a stoichiometric mixture ratio. In some embodiments, the volume of intake gas and the fuel can have an air-fuel ratio (X) of at least about 0.1, at least about 0.2, at least about 0.3, at least about 0.4, at least about 0.5, at least about 0.6, at leastabout 0.7, at least about 0.8, at least about 0.9, at least about 1, at least about 1.1, at least about1.2, at least about 1.3, at least about 1.4, at least about 1.5, at least about 1.6, at least about 1.7, at least about 1.8, at least about 1.9, at least about 2, at least about 3, at least about 4, at least about 5, at least about 6, at least about 7, at least about 8, at least about 9, at least about 10, at least about 20, at least about 30, at least about 40, at least about 50, at least about 60, at least about 70, at least about 80, or at least about 90. In some embodiments, X can be no more than about 100, no more than about 90, no more than about 80, no more than about 70, no more than about 60, no more than about 50, no more than about 40, no more than about 30, no more than about 20, no more than about 10, no more than about 9, no more than about 8, no more than about 7, no more than about 6, no more than about 5, no more than about 4, no more than about 3, no more than about 2, no more than about 1.9, no more than about 1.8, no more than about 1.7, v no more than about 1.6, no more than about 1.5, no more than about 1.4, no more than about 1.3, no more than about 1.2, no more than about 1.1, no more than about 1, no more than about 0.9, no more than about 0.8, no more than about 0.7, no more than about 0.6, no more than about 0.5, no more than about 0.4, no more than about 0.3, or no more than about 0.2. Combinations of the above-referenced values are also possible (e.g., at least about 0.1 and no more than about 100 or at least about 0.5 and no more than about 5), inclusive of all values and ranges therebetween. In some embodiments, X can be about 0.1, about 0.2, about 0.3, about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.9, about 1, about 1.1, about 1.2, about1.3, about 1.4, about 1.5, about 1.6, about 1.7, about 1.8, about 1.9, about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, about 20, about 30, about 40, about 50, about 60, about 70, about 80, about 90, or about 100.

[0070] In some embodiments, step 13 can include combusting at least about 20 wt%, at least about 25 wt%, at least about 30 wt%, at least about 35 wt%, at least about 40 wt%, at least about 45 wt%, at least about 50 wt%, at least about 55 wt%, at least about 60 wt%, at least about 65 wt%, at least about 70 wt%, at least about 75 wt%, at least about 80 wt%, at least about 85 wt%, at least about 90 wt%, at least about 95 wt%, at least about 96 wt%, at least about 97 wt%, at least about 98 wt%, or at least about 99 wt% of the volume of fuel. In some embodiments, step 13 can include combusting substantially all the volume of fuel. In some embodiments, step 13 can include combusting all the volume of fuel. In some embodiments, step 13 can include combusting no more than about 100 wt%, no more than about 99 wt%, no more than about 98 wt%, no more than about 97 wt%, no more than about 96 wt%, no more than about 95 wt%, no more than about 90 wt%, no more than about 85 wt%, no more thanabout 80 wt%, no more than about 75 wt%, no more than about 70 wt%, no more than about 65 wt%, no more than about 60 wt%, no more than about 55 wt%, no more than about 50 wt%, no more than about 45 wt%, no more than about 40 wt%, no more than about 35 wt%, no more than about 30 wt%, or no more than about 25 wt% of the volume of fuel. Combinations of the above-referenced fuel percentages are also possible (e.g., at least about 20 wt% and no more than about 100 wt% or at least about 60 wt% and no more than about 95 wt%), inclusive of all values and ranges therebetween. In some embodiments, step 13 can include combusting about 20 wt%, about 25 wt%, about 30 wt%, about 35 wt%, about 40 wt%, about 45 wt%, about 50 wt%, about 55 wt%, about 60 wt%, about 65 wt%, about 70 wt%, about 75 wt%, about 80 wt%, about 85 wt%, about 90 wt%, about 95 wt%, about 96 wt%, about 97 wt%, about 98 wt%, about 99 wt%, or about 100 wt% of the volume of fuel.

[0071] Step 14 includes moving the exhaust through an exhaust flow path. The exhaust flow path includes a cooled EGR flow path and an uncooled EGR flow path. Any partitioning ratio between the cooled EGR flow path and the uncooled EGR flow path is possible. In some embodiments, at least about 0 vol%, at least about 5 vol%, at least about 10 vol%, at least about 15 vol%, at least about 20 vol%, at least about 25 vol%, at least about 30 vol%, at least about35 vol%, at least about 40 vol%, at least about 45 vol%, at least about 50 vol%, at least about55 vol%, at least about 60 vol%, at least about 65 vol%, at least about 70 vol%, at least about75 vol%, at least about 80 vol%, at least about 85 vol%, at least about 90 vol%, at least about95 vol%, at least about 96 vol%, at least about 97 vol%, at least about 98 vol%, or at least about 99 vol% of the exhaust can pass through the cooled EGR flow path. In some embodiments, no more than about 100 vol%, no more than about 99 vol%, no more than about 98 vol%, no more than about 97 vol%, no more than about 96 vol%, no more than about 95 vol%, no more than about 90 vol%, no more than about 85 vol%, no more than about 80 vol%, no more than about 75 vol%, no more than about 70 vol%, no more than about 65 vol%, no more than about 60 vol%, no more than about 55 vol%, no more than about 50 vol%, no more than about 45 vol%, no more than about 40 vol%, no more than about 35 vol%, no more than about 30 vol%, no more than about 25 vol%, no more than about 20 vol%, no more than about 15 vol%, no more than about 10 vol%, or no more than about 5 vol% of the exhaust gas can pass through the cooled EGR flow path. Combinations of the above-referenced percentages are also possible (e.g., at least about 0 vol% and no more than about 100 vol% or at least about 30 vol% and no more than about 80 vol%), inclusive of all values and ranges therebetween. In some embodiments, about 0 vol%, about 5 vol%, about 10 vol%, about 15 vol%, about 20 vol%,about 25 vol%, about 30 vol%, about 35 vol%, about 40 vol%, about 45 vol%, about 50 vol%, about 55 vol%, about 60 vol%, about 65 vol%, about 70 vol%, about 75 vol%, about 80 vol%, about 85 vol%, about 90 vol%, about 95 vol%, about 96 vol%, about 97 vol%, about 98 vol%, about 99 vol%, or about 100 vol% of the exhaust can pass through the cooled EGR flow path.

[0072] In some embodiments, at least about 0 vol%, at least about 5 vol%, at least about 10 vol%, at least about 15 vol%, at least about 20 vol%, at least about 25 vol%, at least about 30 vol%, at least about 35 vol%, at least about 40 vol%, at least about 45 vol%, at least about 50 vol%, at least about 55 vol%, at least about 60 vol%, at least about 65 vol%, at least about 70 vol%, at least about 75 vol%, at least about 80 vol%, at least about 85 vol%, at least about 90 vol%, at least about 95 vol%, at least about 96 vol%, at least about 97 vol%, at least about 98 vol%, or at least about 99 vol% of the exhaust can pass through the uncooled EGR flow path. In some embodiments, no more than about 100 vol%, no more than about 99 vol%, no more than about 98 vol%, no more than about 97 vol%, no more than about 96 vol%, no more than about 95 vol%, no more than about 90 vol%, no more than about 85 vol%, no more than about 80 vol%, no more than about 75 vol%, no more than about 70 vol%, no more than about 65 vol%, no more than about 60 vol%, no more than about 55 vol%, no more than about 50 vol%, no more than about 45 vol%, no more than about 40 vol%, no more than about 35 vol%, no more than about 30 vol%, no more than about 25 vol%, no more than about 20 vol%, no more than about 15 vol%, no more than about 10 vol%, or no more than about 5 vol% of the exhaust gas can pass through the uncooled EGR flow path. Combinations of the above-referenced percentages are also possible (e.g., at least about 0 vol% and no more than about 100 vol% or at least about 30 vol% and no more than about 80 vol%), inclusive of all values and ranges therebetween. In some embodiments, about 0 vol%, about 5 vol%, about 10 vol%, about 15 vol%, about 20 vol%, about 25 vol%, about 30 vol%, about 35 vol%, about 40 vol%, about 45 vol%, about 50 vol%, about 55 vol%, about 60 vol%, about 65 vol%, about 70 vol%, about 75 vol%, about 80 vol%, about 85 vol%, about 90 vol%, about 95 vol%, about 96 vol%, about 97 vol%, about 98 vol%, about 99 vol%, or about 100 vol% of the exhaust can pass through the uncooled EGR flow path.

[0073] Step 15 includes estimating a cylinder wall temperature (Tw) and estimating a TDC gas temperature (TTDC) in the compression ignition engine. In some embodiments, a thermal model can be used to predict metal temperatures and TDC gas temperatures from other inputs. The estimated cylinder wall and TDC gas temperatures can be considered to manipulate operation of the compression ignition engine to reduce the metal temperatures to below amechanical limit. This can be used to keep TDC temperatures above a combustion stability limit. In some embodiments, step 15 can include measuring a single valve bridge of a single combustion chamber. In some embodiments, step 15 can include measuring valve bridge temperatures of about 1, about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, about 11, about 12, about 13, about 14, about 15, about 16, about 17, about 18, about 19, about 20, about 21, about 22, about 23, about 24, about 25, about 26, about 27, about 28, about 29, about 30, about 31, or about 32 combustion chambers, inclusive of all values and ranges therebetween. In some embodiments, the valve bridge temperature can be measured via a thermocouple and / or a temperature transducer. In some embodiments, the valve bridge temperature can be transmitted to a user interface.

[0074] Step 16 includes adjusting one or more engine parameters based on the estimated cylinder wall temperature and TDC gas temperature. In some embodiments, the adjustment can include adjusting the ratio of intake gas between the CAC, the CAC bypass, and / or the subcooled air cooler, consistent with any of the volume percentages described above with respect to step 11. In some embodiments, the adjustment can include adjusting the ratio of exhaust between the cooled EGR flow path and the uncooled EGR flow path. For example, if the estimated cylinder wall temperature or measured valve bridge temperature is greater than a setpoint, then step 16 can include directing a greater amount of intake gas through the CAC, as opposed to the CAC bypass. If the estimated cylinder wall temperature or measured valve bridge temperature is less than a setpoint (e.g., during startup or cold start), then step 16 can include directing a greater amount of intake gas through the CAC bypass, as opposed to the CAC. If the estimated cylinder wall temperature or measured valve bridge temperature is greater than a setpoint, then step 16 can include directing a greater amount of exhaust through the cooled EGR flow path, as opposed to the uncooled EGR flow path. If the estimated cylinder wall temperature or measured valve bridge temperature is less than a setpoint, then step 16 can include directing a greater amount of exhaust through the uncooled EGR flow path, as opposed to the cooled EGR flow path.

[0075] In some embodiments, step 16 can include deactivating at least one cylinder to concentrate more heat in the remaining cylinders. In some embodiments, the deactivation of the cylinder can include closing the intake valve and the exhaust valve and deactivating the fuel injector. Further descriptions of cylinder deactivation are described in U.S. Patent Publication No. 2022 / 0018297 (“the ‘297 publication”), filed September 30, 2021 and titled“Systems and Methods of Cylinder Deactivation in High-Temperature Mixing-Controlled Engines,” the disclosure of which is hereby incorporated by reference in its entirety.

[0076] In some embodiments, step 16 can include adjusting the heat setting of an intake manifold heater. In some embodiments, step 16 can include turning on or off an intake manifold heater. In some embodiments, step 16 can include adjusting the heat setting of a block heater. In some embodiments, step 16 can include turning on or off a block heater. In some embodiments, step 16 can include adjusting an air-fuel ratio. For example, step 16 can include increasing the engine load. In some embodiments, the air-fuel ratio can be adjusted to a lean mixture if the estimated cylinder wall temperature or measured valve bridge temperature is higher than the setpoint. In some embodiments, the air-fuel ratio can be adjusted to a stoichiometric mixture. In some embodiments, the air-fuel ratio can be adjusted to a fuel-rich mixture.

[0077] FIG. 8 is a logic schematic of a method of operating a compression ignition engine, according to an embodiment. The methods and apparatus described herein can be employed to keep the TDC gas temperature well above the minimum for combustion stability at light load, while keeping wall metal temperature below the mechanical limits at a high load. As shown, fixed parameters (e.g., engine geometry, valve timing, cylinder number), resultant parameters (e.g., engine speed and % torque (wall heat losses, exhaust temperature), coolant and / or oil temperature), and targeted parameters (e.g., intake manifold temperature, grid heat or other heat, intake and exhaust manifold pressures (residual trapping), charge cooling from pilot injections) are all fed to system models and estimators. The system models and estimators can include wall temperature models for specific cylinders, which take into account heat transfer, coolant temperature, charge motion, and time since the engine was started. The system models and estimators can also include a TDC temperature estimator for a specific cylinder. TDC temperature upper bounds can be informed by metal temperature limits, metal properties, and / or coatings. TDC temperature lower bounds can be informed by a fuel dependent temperature needed for a target desired ignition delay time (e.g., < 1-2 ms). When evaluating the parameters of the engine, the logic and feedback of the system can evaluate whether the metal temperatures are within the design limits and send feedback to thermal management control systems for the intake temperature. If the TDC temperature is in the desired temperature range, feedback can be sent to the thermal management controls system for the intake temperature. If any cylinder’s TDC temperature estimation is below the lower bound for ignition or above the metal temperature limit, the target parameters can be adjusted.

[0078] In some embodiments, an engine can employ the strategies described herein in parallel. While independent use of each of these methods is possible, their combination is within the scope of this disclosure.

[0079] Various concepts may be embodied as one or more methods, of which at least one example has been provided. The acts performed as part of the method may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include performing some acts simultaneously, even though shown as sequential acts in illustrative embodiments. Put differently, it is to be understood that such features may not necessarily be limited to a particular order of execution, but rather, any number of threads, processes, services, servers, and / or the like that may execute serially, asynchronously, concurrently, in parallel, simultaneously, synchronously, and / or the like in a manner consistent with the disclosure. As such, some of these features may be mutually contradictory, in that they cannot be simultaneously present in a single embodiment. Similarly, some features are applicable to one aspect of the innovations, and inapplicable to others.

[0080] In addition, the disclosure may include other innovations not presently described. Applicant reserves all rights in such innovations, including the right to embodiment such innovations, file additional applications, continuations, continuations-in-part, divisionals, and / or the like thereof. As such, it should be understood that advantages, embodiments, examples, functional, features, logical, operational, organizational, structural, topological, and / or other aspects of the disclosure are not to be considered limitations on the disclosure as defined by the embodiments or limitations on equivalents to the embodiments. Depending on the particular desires and / or characteristics of an individual and / or enterprise user, database configuration and / or relational model, data type, data transmission and / or network framework, syntax structure, and / or the like, various embodiments of the technology disclosed herein may be implemented in a manner that enables a great deal of flexibility and customization as described herein.

[0081] All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meanings of the defined terms.

[0082] As used herein, in particular embodiments, the terms “about” or “approximately” when preceding a numerical value indicates the value plus or minus a range of 10%. Where arange of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within the disclosure. That the upper and lower limits of these smaller ranges can independently be included in the smaller ranges is also encompassed within the disclosure, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the disclosure.

[0083] The phrase “and / or,” as used herein in the specification and in the embodiments, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and / or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and / or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and / or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

[0084] As used herein in the specification and in the embodiments, “or” should be understood to have the same meaning as “and / or” as defined above. For example, when separating items in a list, “or” or “and / or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of’ or “exactly one of,” or, when used in the embodiments, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e., “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of,” when used in the embodiments, shall have its ordinary meaning as used in the field of patent law.

[0085] As used herein in the specification and in the embodiments, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarilyincluding at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and / or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.

[0086] As used herein, “fuel” can refer to any material capable of producing an exothermic chemical reaction with an intake mixture, regardless of the fuel’s cetane number. This can include fuels and blends of: naphtha, gasoline, alcohol fuels (including butanol, propanol, ethanol, and methanol), gaseous hydrocarbons (including natural gas, methane, ethane, propane, butane, hexane, etc.) and alternative fuels such as hydrogen, ammonia, syngas, CO, etc.

[0087] As used herein, “plume” can refer to a mass of fuel spreading from an injection point, which may be entraining or mixing with the volume of intake charge as it progresses spatially and / or temporally during a fuel injection event.

[0088] As used herein, “intake charge” refers to a volume of material that enters a combustion chamber prior to a combustion event. The intake charge can include air, atmospheric air, humid air, air enriched with oxygen, air diluted with exhaust gas, air diluted with inert gas, fuel, uncombusted fuel, or any combination thereof.

[0089] As used herein, “small-molecule fuels” refers to fuels having less than or equal to four carbon atoms per molecule on average (including zero carbon atoms per molecule). This can include hydrogen, ammonia, carbon monoxide (CO), syngas, natural gas, methane, methanol, ethane, ethene, ethanol, di-methyl-ether, propane, propanol, butane, butanol, isobutanol, and other fuels and fuel blends meeting the criteria of less than or equal to four carbon atoms per molecule on average.

[0090] As used herein, “combustion efficiency” can refer to the degree to which air and fuel are fully combusted to form the products of complete combustion. As a non-limiting example, combustion efficiency can be calculated using lower heating value (LHV) of the fuel (e.g., ethanol, methanol, etc.) and combustion products (e.g., CO2, H2O, etc.), as set forth below:Where:’Icombustion is the combustion efficiency;LHVproductsis the LHV of the combustion products (MJ / kg); massproductsis the mass of the combustion products (kg);LHVfUei is the LHV of the fuel (MJ / kg); and massfueiis the mass of the fuel (kg).

[0091] As used herein, “efficiency,” “thermal efficiency,” or “LHV efficiency” can refer to the conversion of fuel energy to mechanical work, calculated as follows:WorkT] = -LHVUeiincisSfueiWhere: i] is the efficiency;Work is the amount of mechanical work achieved (J), which can be the indicated work calculated from the pressure in the engine cylinder, or the brake work, where the work is measured at the point of the rotating shaft going from the engine into a transmission or generator (i.e., the “brake thermal efficiency);LHVfueiis the LHV of the fuel (J / kg); and massfueiis the mass of the fuel (kg).

[0092] As used herein, a numerical definition of a “crank angle” or an “engine crank angle” should be understood as the crank angle relative to a fixed point in the engine cycle (as described below in Table 1 for the case of a four-stroke engine). In other words, in a four- stroke engine, the engine crank angle is 0° (or 720°) when the piston is in the TDC position between the exhaust stroke and the intake stroke. The engine crank angle is 360° when thepiston is in the TDC position between the compression stroke and the expansion stroke. The engine crank angle is 540° when the piston is in the BDC position between the expansion stroke and the exhaust stroke. The engine crank angle is 180° when the piston is in the BDC position between the intake stroke and the compression stroke. Negative numbers can also be used to describe the crank angle relative to the TDC position between the exhaust stroke and the intake stroke. In other words, 540° can also be described as -180°, 360° can also be described as - 360°, and 180° can also be described as -540°.Table 1. Crank Angle Descriptions for a Four Stroke Engine

[0093] In some embodiments, the term “immediately prior to ignition” or “just prior to ignition” can refer to a temporal point, at which the engine crank angle is about 300°, about 305°, about 310°, about 315°, about 320°, about 325°, about 330°, about 335°, about 340°, about 345°, about 350°, about 355°, about 360°, about 365°, about 370°, about 375°, or about 380°, inclusive of all values and ranges therebetween.

[0094] In some embodiments, the term “immediately prior to ignition” or “just prior to ignition” can refer to a temporal point of approximately 50 ms, approximately 40 ms, approximately 30 ms, approximately 20 ms, approximately 10 ms, approximately 5 ms, approximately 2 ms, approximately 1 ms, approximately 0.5 ms, or approximately 0.1 ms, prior to ignition, inclusive of all values and ranges therebetween.

[0095] In some embodiments, the term “immediately prior to ignition” or “just prior to ignition” can refer to a temporal point preceding the time at which 5% of the fuel exothermicity is observed to have happened. In other words, the fuel can be considered to have ignited when a measurable deviation in pressure could be detected to indicate exothermic fuel oxidation is occurring.

[0096] In some embodiments, the term “immediately prior to ignition” or “just prior to ignition” can refer to a temporal point about 1 crank angle degree, about 2 crank angle degrees, about 3 crank angle degrees, about 4 crank angle degrees, about 5 crank angle degrees, about6 crank angle degrees, about 7 crank angle degrees, about 8 crank angle degrees, about 9 crank angle degrees, about 10 crank angle degrees, about 11 crank angle degrees, about 12 crank angle degrees, about 13 crank angle degrees, about 14 crank angle degrees, about 15 crank angle degrees, about 16 crank angle degrees, about 17 crank angle degrees, about 18 crank angle degrees, about 19 crank angle degrees, or about 20 crank angle degrees prior to ignition, inclusive of all values and ranges therebetween.

[0097] In some embodiments, the term “immediately prior to ignition” or “just prior to ignition” can refer to a temporal point about 50 ms, about 40 ms, about 30 ms, about 20 ms, about 10 ms, about 5 ms, about 2 ms, or about 1 ms prior to ignition, inclusive of all values and ranges therebetween.

[0098] In some embodiments, the term “immediately prior to fuel injection” or “just prior to fuel injection” can refer to a temporal point about 1 crank angle degree, about 2 crank angle degrees, about 3 crank angle degrees, about 4 crank angle degrees, about 5 crank angle degrees, about 6 crank angle degrees, about 7 crank angle degrees, about 8 crank angle degrees, about 9 crank angle degrees, about 10 crank angle degrees, about 11 crank angle degrees, about 12 crank angle degrees, about 13 crank angle degrees, about 14 crank angle degrees, about 15 crank angle degrees, about 16 crank angle degrees, about 17 crank angle degrees, about 18 crank angle degrees, about 19 crank angle degrees, or about 20 crank angle degrees prior to fuel injection, inclusive of all values and ranges therebetween.

[0099] In some embodiments, the term “immediately prior to fuel injection” or “just prior to fuel injection” can refer to a temporal point about 50 ms, about 40 ms, about 30 ms, about 20 ms, about 10 ms, about 5 ms, about 2 ms, or about 1 ms prior to fuel injection, inclusive of all values and ranges therebetween.

[0100] In some embodiments, the term “valve closing” (e.g., “intake valve closing” or “exhaust valve closing”) can refer to a temporal point, wherein the valve becomes fully seated (i.e., 0 mm valve lift). In some embodiments, the term “valve opening” (e.g., “intake valve opening” or “exhaust valve opening”) can refer to a temporal point, wherein the valve becomes unseated (i.e., >0 mm lift).

[0101] In the embodiments, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of’ and “consisting essentially of’ shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.

[0102] In some embodiments, the novel, high-temperature mixing-controlled strategy described herein can be implemented in an opposed piston engine. This could include 2 or more pistons configured to compress an inducted charge, the engine potentially having no cylinder head. This could be a two-four-or other number of stroke design.

[0103] While specific embodiments of the present disclosure have been outlined above, many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, the embodiments set forth herein are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the disclosure. Where methods and steps described above indicate certain events occurring in a certain order, those of ordinary skill in the art having the benefit of this disclosure would recognize that the ordering of certain steps may be modified and such modification are in accordance with the variations of the invention. Additionally, certain of the steps may be performed concurrently in a parallel process when possible, as well as performed sequentially as described above. The embodiments have been particularly shown and described, but it will be understood that various changes in form and details may be made.

Claims

Claims1. A method of operating a compression ignition engine, the method comprising: moving a volume of air through an intake flow path of the compression ignition engine, the intake flow path including a charge air cooler (CAC) and a CAC bypass; moving the volume of air into a combustion chamber via an intake manifold; combusting a volume of fuel in the combustion chamber to form exhaust, the volume of fuel having a cetane number less than about 40; moving the exhaust through an exhaust flow path, the exhaust flow path including a cooled exhaust gas recirculation (EGR) flow path and an uncooled EGR flow path; estimating a cylinder wall temperature and a TDC gas temperature via functions based on engine geometry, measured engine operating parameters and engine control parameters in the compression ignition engine; and based on the estimated cylinder wall temperature and estimated TDC gas temperature, adjusting at least one of: a ratio of air flow through the CAC to the air flow through the CAC bypass; or a ratio of exhaust flow through the cooled EGR flow path to exhaust flow through the uncooled EGR flow path.

2. The method of claim 1, wherein the intake manifold includes an intake manifold heater, the method further comprising: adjusting a setting of the intake manifold heater based on estimated TDC temperature and estimated wall temperatures.

3. The method of claim 1, wherein the compression ignition engine further includes a radiator in contact with the CAC, the method further comprising: adjusting a setting of the radiator based on estimated TDC temperature and estimated wall temperatures .

4. The method of claim 1, further comprising: measuring an intake manifold temperature of the compression ignition engine.

5. A compression ignition engine, comprising: an intake air flow path;a charge air cooler (CAC) disposed along the intake air flow path; a CAC bypass disposed along the intake air flow path; a combustion chamber; an exhaust flow path; a cooled exhaust gas recirculation (EGR) flow path disposed along the exhaust flow path; an uncooled EGR flow path disposed along the exhaust flow path; and a controller configured to adjust, based on an estimated TDC temperature and estimated wall temperatures in the compression ignition engine, at least one of: a ratio of air flow through the CAC to the air flow through the CAC bypass; or a ratio of exhaust flow through the cooled EGR flow path to exhaust flow through the uncooled EGR flow path.

6. The compression ignition engine of claim 5, further comprising: an intake manifold heater.

7. The compression ignition engine of claim 5, further comprising: a radiator in contact with the CAC.

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