Refine Your Search

Topic

Author

Affiliation

Search Results

Technical Paper

Ducted Fuel Injection: Confirmed re-entrainment hypothesis

2024-04-09
2024-01-2885
Testing of ducted fuel injection (DFI) in a single-cylinder engine with production-like hardware previously showed that simply adding a duct structure increased soot emissions at the full load, rated speed operating point. In the authors’ 2021 SAE paper, which reported these findings, it was hypothesized that the DFI flame, which is faster than a conventional diesel combustion (CDC) flame, and has a shorter distance to travel, was being re-entrained into the on-going injection around the lift-off length, thus reducing air entrainment into the on-going injection. The engine operating condition and the engine combustion chamber geometry were duplicated in a constant pressure vessel. The experimental setup used a 3D piston section combined with a glass fire deck allowing for a comparison between a CDC flame and a DFI flame via high-speed imaging. Testing clearly confirmed the detrimental effect of the DFI flame re-entrainment hypothesis presented in the previous on-engine work.
Technical Paper

Combustion Chamber Development for Flat Firedeck Heavy-Duty Natural Gas Engines

2024-04-09
2024-01-2115
The widely accepted best practice for spark-ignition combustion is the four-valve pent-roof chamber using a central sparkplug and incorporating tumble flow during the intake event. The bulk tumble flow readily breaks up during the compression stroke to fine-scale turbulent kinetic energy desired for rapid, robust combustion. The natural gas engines used in medium- and heavy-truck applications would benefit from a similar, high-tumble pent-roof combustion chamber. However, these engines are invariably derived from their higher-volume diesel counterparts, and the production volumes are insufficient to justify the amount of modification required to incorporate a pent-roof system. The objective of this multi-dimensional computational study was to develop a combustion chamber addressing the objectives of a pent-roof chamber while maintaining the flat firedeck and vertical valve orientation of the diesel engine.
Technical Paper

Advancements in Combustion Modeling and Simulation for an Innovative Homogeneous Reactivity-Controlled Compression Ignition (hRCCI) concept

2024-04-09
2024-01-2691
The global imperative to develop clean energy solutions has redirected research efforts towards highly efficient combustion engines with ultra-low emissions. This has prompted investigations into alternative combustion concepts, including Low Temperature Combustion (LTC), utilizing environmentally friendly fuels. Within the scope of our research project, we are primarily focused on the development of an innovative combustion concept known as Homogeneous Reactivity-Controlled Compression Ignition (hRCCI), which employs renewable fuels such as ethanol and 1-octanol for a serial hybrid powertrain. Regrettably, the lack of predictive simulations for this concept presents a significant challenge in optimizing the engine's operation. Most of the 1D system simulation models use a non-predictive combustion model for combustion simulations. Due to the dependence on auto-ignition chemistry, a chemistry based HCCI combustion model for real time computation has been proposed with this work.
Technical Paper

Downsizing a Heavy-Duty Natural Gas Engine by Scaling the Air Handling System and Leveraging Phenomenological Combustion Model

2024-04-09
2024-01-2114
A potential route to reduce CO2 emissions from heavy-duty trucks is to combine low-carbon fuels and vehicle electrification/hybridization. Hybridization offers the potential to downsize the engine. Although engine downsizing in the light-duty sector can offer significant fuel economy savings mainly due to increased part-load efficiency, its benefits and downsides in heavy-duty engines are less clear. As there has been limited published research in this area to date, there is a lack of a standardized engine downsizing procedure. This paper aims to use an experimentally validated one-dimensional phenomenological combustion model in a commercial engine simulation software GT-Power alongside turbocharger scaling methods to develop downsized engines from a baseline 6-cylinder (2.2 L/cyl, 26 kW/L) pilot-ignition, direct-injection natural gas engine.
Technical Paper

Numerical Study on the Combustion Characteristics of an Ammonia/Hydrogen Engine with Active Prechamber Ignition

2024-04-09
2024-01-2104
With the implementation of global carbon reduction policies, there has been a growing emphasis on the research of zero-carbon fuels. Both ammonia and hydrogen, as zero-carbon fuels for internal combustion engines, come with their own set of advantages and disadvantages. Jet ignition, known for its high ignition energy and rapid flame propagation velocity, offers a more effective ignition means of combining ammonia and hydrogen than spark ignition for use in the engine. This paper, while maintaining the lambda value of 1, conducted a numerical study to assess the impact of various prechamber structures on the combustion characteristics of an ammonia/hydrogen engine. Firstly, the nozzles angle emerges as a critical parameter in the design of active prechamber structures.
Technical Paper

Combustion analysis of Hydrogen-DDF mode based on OH* chemiluminescence images

2024-04-09
2024-01-2367
Hydrogen-diesel dual-fuel combustion processes were studied in a rapid compression and expansion engine (RCEM). In the experiments, the combustion processes were visualized using an optically accessible RCEM that can simulate a single compression and expansion stroke of a diesel engine. A small amount of diesel was injected as a pilot ignition for the hydrogen, with injection pressures of 40, 80, and 120 MPa using a common rail injection system. The amount of diesel injected was varied as 3, 6, and 13 mm3. The hydrogen-air mixture was introduced into the combustion chamber through the intake valve. The amount of hydrogen was manipulated by varying the total excess air ratio(λtotal) at 3 and 4. The RCEM was operated at a constant speed of 900 rpm, and the in-cylinder pressure and temperature at TDC were set at 5 MPa and 700 K, respectively.
Technical Paper

Next Generation High Efficiency Boosted Engine Concept

2024-04-09
2024-01-2094
Ford Motor Company, working with FEV North America and Oak Ridge National Laboratory, developed a concept for a next generation of boosted spark ignited engine for application in light-duty on-highway vehicles. Key goals were 23% improved fuel economy and 15% reduced weight compared to a baseline 2016 Model Year Ford 3.5 L Ecoboost engine system in the lead application of a Ford F150. Additional requirements include the use of conventional regular E10 gasoline fuel and conventional exhaust aftertreatment employing 3-way catalyst technology for compliance with U.S. and global pollutant emissions regulations. A modular inline 6-cylinder engine whose technical assumptions include high 14:1 geometric compression ratio, large stroke-to-bore ratio of 1.33, continuously variable intake valve lift and timing, variable geometry turbocharger, active pre-chamber ignition system, cooled low pressure EGR, and innovative active cooling system.
Technical Paper

Performance of Spark Current Boost System on a Production Engine under Lean-Burn Conditions

2024-04-09
2024-01-2106
In order to improve the fuel economy for future high-efficiency spark ignition engines, the applications of advanced combustion strategies are considered to be beneficial with an overall lean and/or exhaust gas recirculation (EGR) diluted cylinder charge. Stronger and more reliable ignition sources become more favorable under extreme lean/EGR conditions. Recent research results from the author’s lab show that the multi-core ignition system with discharge energy distribution strategy can provide robust ignition control under a wide range of engine loads, while only showing major ignition benefits under low load, lean limit conditions, where ignition receives major challenges. Besides, the research in the authors’ lab indicates that the frequency of plasma restrikes increases with increased flow velocity and decreased discharge current level, and a higher discharge current can reduce the gap resistance and maintain the stretched plasma for a longer duration under flow conditions.
Technical Paper

Study of Dimethyl Ether Fuel Spray Characteristics and Injection Profile

2024-04-09
2024-01-2702
The majority of transportation systems have continued to be powered by the internal combustion engine and fossil fuels. Heavy-duty applications especially are reliant on diesel engines for their high brake efficiency, power density, and robustness. Although engineering developments have advanced engines towards significantly fewer emissions and higher efficiency, the use of fossil-derived diesel as fuel sets a fundamental threshold in the achievable total net carbon reduction. Dimethyl ether can be produced from various renewable feedstocks and has a high chemical reactivity making it suitable for heavy-duty applications, namely compression ignition direct injection engines. Studies of dimethyl ether for engine combustion have shown positive results with an ultra-low propensity to form soot regardless of NOx levels. Further reduction in NOx and soot emission regulations presents a significant challenge to combustion performance.
Technical Paper

Numerical study on the design of a passive prechamber on a heavy-duty hydrogen combustion engine

2024-04-09
2024-01-2112
Lean-burning hydrogen internal combustion engines are potentially a good option for future transportation solutions since they do not emit carbon-dioxide and unburned hydro-carbons, and the emissions of nitric-oxides can be kept low. However, under lean-burn conditions the combustion duration increases and the combustion stability decreases, leading to a reduced thermal efficiency. Turbulent jet ignition (TJI) can be used to extend the lean-burn limit, while decreasing the combustion duration and improving combustion stability. The objective of this paper is to investigate the feasibility of a passive prechamber TJI system on a heavy-duty hydrogen engine under lean-burn conditions using CFD modelling. The studied concept is mono-fuel, port-fuel injected, and spark ignited in the prechamber. The overall design of the prechamber is discussed and the effect of certain design parameters have on the engine performance are studied.
Technical Paper

The New Toyota 2.4L L4 Turbo Engine with 8AT and 1-Motor Hybrid Electric Powertrains for Midsize Pick-up Trucks

2024-04-09
2024-01-2089
It is more and more challenging for internal combustion engines in pick-up trucks which have heavy weight and high drag, to fulfill both strict fuel economy and emission regulations toward the target of “Carbon Neutrality”, while exceeding customer expectations. To overcome these difficult tasks, Toyota has developed the new 2.4L L4 turbocharged gasoline engine which for the first time complies with severe emission regulations such as Tier3 Bin30/LEVIII SULEV30 for body-on-frame midsize pick-up trucks. At the same time, both thermal-efficiency and maximum torque are improved by adopting high-speed combustion to the turbocharged engine based on the TNGA (Toyota New Global Architecture) platform, spray guide combustion by center direct injection in combustion chamber, quick light-off close-coupled three-way catalyst and a quick response turbocharger.
Technical Paper

Cylinder Head Insulation Plate, Design, Analysis and Testing for an Extreme High Efficiency Internal Combustion Engine

2024-04-09
2024-01-2831
The main objective of this paper is to describe the design, analysis and testing of a novel method of insulating the combustion chamber, which is key for efficiency demonstration on a new class of internal combustion engine (ICE). A recuperated split cycle engine (RSCE) has unique demands for heat loss reduction. In particular during the combustion event, to minimize the heat losses is a must to achieve high efficiency. The insulation is provided by a metal plate that is assembled into the cylinder head to line the combustion chamber surface. The design has been focused on reducing heat transfer surface area and exploiting contact gap thermal resistance between the upper surface of the plate and the cylinder head, thus reducing heat wasted to the coolant circuit. In this paper, the plate requirements, functions, design, analysis and test results from a research and development (R&D) program of a heavy duty (HD) recuperated split cycle engine are reported.
Technical Paper

Numerical Investigation on Hydrogen Enrichment and EGR on In-Cylinder Soot and NOx Formation in Dual-Fuel CI-Engine

2024-04-09
2024-01-2098
To mitigate the NOx emissions from diesel engines, the adoption of exhaust gas recirculation (EGR) has gained widespread acceptance as a technology. Nonetheless, employing EGR has the drawback of elevating soot emissions. The use of hydrogen-enriched air with EGR in a diesel engine (dual-fuel operation), offers the potential to decrease in-cylinder soot formation while simultaneously reducing NOx emissions. The present study numerically investigates the effect of hydrogen energy share and engine load on the formation and emission of soot and NOx emission from hydrogen-diesel dual-fuel engine. The numerical investigation is performed using an n-heptane/H2 reduced reaction mechanism with a two-step soot model in ANSYS FORTE. To enhance the accuracy of predicting dual-fuel combustion in a hydrogen-diesel dual-fuel engine, a reduced n-heptane reaction mechanism is integrated with a hydrogen reaction mechanism using CHEMKIN.
Technical Paper

Effect of Baffle Height on the In-Cylinder Air-Fuel Mixture Preparation in a Gasoline Direct Injection Engine: A Computational Fluid Dynamics Analysis

2024-04-09
2024-01-2697
In-cylinder fluid dynamics enhance performance and emission characteristics in internal combustion (IC) engines. Techniques such as helical ports, valve shrouding, masking, and modifications to piston profiles or vanes in ports are employed to achieve the desired incylinder flows in these engines. However, due to space constraints, modifications to the cylinder head are typically minimal. The literature suggests that introducing baffles into the combustion chamber of an IC engine can enhance in-cylinder flows, air-fuel mixing, and, subsequently, stratification. Studies have indicated that the height of the baffles plays a significant role in determining the level of improvement in in-cylinder flow and air-fuel mixing. Therefore, this study employs Computational fluid dynamics (CFD) analysis to investigate the impact of baffle height on in-cylinder flow and air-fuel mixing in a four-stroke, four-valve, spray-guided gasoline direct injection (GDI) engine.
Technical Paper

A comparative study of knock formation in gasoline and methanol combustion using a multiple spark ignition approach: an optical investigation

2024-04-09
2024-01-2105
Engine knock is a major barrier to achieving higher engine efficiency by increasing the compression ratio of the engine. It is an abnormal event caused by the autoignition of air-fuel mixture ahead of the propagating flame front. A higher octane number fuel can be a good solution to reduce or eliminate the higher knock intensity and obtain better engine performance. Methanol is a promising alternative fuel, which has a higher octane number and can be produced from conventional and non-conventional energy resources to reduce pollutant emissions. This study compares the combustion characteristics of gasoline and methanol fuels in an optical spark-ignition engine using multiple spark plugs. The experiment was performed on a single-cylinder four-stroke optical engine. A customized metal liner equipped with four circumferential spark plugs was used to generate multiple flame kernels inside the combustion chamber.
Technical Paper

Development of the New V6 Twin-Turbocharged Engine for Flagship SUV

2024-04-09
2024-01-2095
As part of Nissan’s strategy of electrification and the shift to smart technologies, our powertrain department has two main pillars: zero emissions and ICE Evolution. As a core unit of ICE Evolution, we have developed a brand new V6 Twin turbocharged gasoline engine for Nissan’s next generation full-size flagship SUV to deliver luxury and toughness at the highest level. This brand-new engine will be applied to vehicles in all corners of the world and must have strong performance in every corner. In other words, it has to meet the latest emissions and fuel efficiency regulations, have strong power performance beyond expectation, and provide reliable drivability on rough roads and deserts. To achieve these requirements, the new engine is incorporating a lot of cutting-edge technologies.
Technical Paper

Experimental investigation of internal and external EGR effects on a CNG-OME dual-fuel engine

2024-04-09
2024-01-2361
With the increasing demands to reduce the carbon footprint and emissions, engines powered by e-fuels offer a possibility for sustainable transportation solutions. This work focuses on the effect of exhaust gas rebreathing and external EGR (Exhaust Gas Recirculation) in a CNG (Compressed Natural Gas)-OME (Polyoxymethylene Ether) dual-fuel engine. A four-cylinder heavy-duty engine was used to conduct the engine tests at different load points from 1100rpm to 1600 rpm and 4.9 to 14.7 bar brake mean effective pressure (BMEP). The quantities of the high (HRF) and the low reactivity fuel (LRF) were varied, as were the external and internal EGR rates and their combination. CNG was injected into the intake manifold to create a homogeneous air-fuel mixture, while OME was introduced as a pilot injection directly into the combustion chamber. Results show an increase in THC and CO emissions, while NOx emissions are significantly reduced compared to diesel operation.
Journal Article

Modal Analysis of Combustion Chamber Acoustic Resonance to Reduce High-Frequency Combustion Noise in Pre-Chamber Jet Ignition Combustion Engines

2024-01-31
Abstract The notable increase in combustion noise in the 7–10 kHz band has become an issue in the development of pre-chamber jet ignition combustion gasoline engines that aim for enhanced thermal efficiency. Combustion noise in such a high-frequency band is often an issue in diesel engine development and is known to be due to resonance in the combustion chamber. However, there are few cases of it becoming a serious issue in gasoline engines, and effective countermeasures have not been established. The authors therefore decided to elucidate the mechanism of high-frequency combustion noise generation specific to this engine, and to investigate effective countermeasures. As the first step, in order to analyze the combustion chamber resonance modes of this engine in detail, calculation analysis using a finite element model and experimental modal analysis using an acoustic excitation speaker were conducted.
Journal Article

Development of a Turbulent Jet-Controlled Compression Ignition Engine Concept Using Spray-Guided Stratification for Fueling a Passive Prechamber

2024-01-24
Abstract Improving thermal efficiency of an internal combustion engine is one of the most cost-effective ways to reduce life cycle-based CO2 emissions for transportation. Lean burn technology has the potential to reach high thermal efficiency if simultaneous low NOx, HC, and CO emissions can be achieved. Low NOx can be realized by ultra-lean (λ ≥ 2) spark-ignited combustion; however, the HC and CO emissions can increase due to slow flame propagation and high combustion variability. In this work, we introduce a new combustion concept called turbulent jet-controlled compression ignition, which utilizes multiple turbulent jets to ignite the mixture and subsequently triggers end gas autoignition. As a result, the ultra-lean combustion is further improved with reduced late-cycle combustion duration and enhanced HC and CO oxidation. A low-cost passive prechamber is innovatively fueled using a DI injector in the main combustion chamber through spray-guided stratification.
Technical Paper

High-Efficiency Methanol Engine Development for Heavy Commercial Vehicles

2024-01-18
2024-01-5005
Under China’s “3060” target of carbon peak and carbon neutrality, heavy commercial vehicles are a key breakthrough point to promote the automobile industry to achieve carbon peaking and carbon neutrality goals. Green methanol, as a clean alternative fuel, are an effective technical route for heavy commercial vehicles to achieve energy conservation and emission reduction. Based on a 13L methanol engine, this study fully considers the methanol combustion characteristics, the ω shape combustion system of the base engine is redesigned as a pent-roof combustion chamber. The intake port is changed from a swirl port to a high-tumble port, and the piston crown is also adjusted adaptively. At the same time, the cam profile, cooling water jacket, intake and exhaust system are redesigned, and the turbocharger is re-matched according to the physical properties of methanol. CAE tools and means are used to optimize and determine the design proposal.
X