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Technical Paper

Development and Validation of a Three Pressure Analysis (TPA) GT-Power Model of the CFR F1/F2 Engine for Estimating Cylinder Conditions

2018-04-03
2018-01-0848
The CFR engine is the widely accepted platform to test standard Research Octane Number (RON) and Motored Octane Number (MON) for determining anti-knock characteristics of motor fuels. With increasing interest in engine downsizing, up-torquing, and alternative fuels for modern spark ignition (SI) engines, there is a need to better understand the conditions that fuels are subjected to in the CFR engine during octane rating. To take into account fuel properties, such as fuel heat of vaporization, laminar flame speed and auto-ignition chemistry; and understand their impacts on combustion knock, it is essential to estimate accurate cylinder conditions. In this study, the CFR F1/F2 engine was modeled using GT-Power with the Three Pressure Analysis (TPA) and the model was validated for different fuels and engine conditions.
Technical Paper

In-Cylinder Oxygen Mass Fraction Estimation Method for Minimizing Cylinder-to-Cylinder Variations

2015-04-14
2015-01-0874
Recent developments in advanced combustion engines have demonstrated the potential increases in efficiency and reductions in emissions through low temperature combustion (LTC). These combustion modes often rely on high exhaust gas recirculation (EGR), early fuel injection systems, and in some cases a combination of fuels with different reactivities. Despite the advantages of LTC, such operations are highly sensitive to the in-cylinder pre-combustion conditions and face significant challenges in multi-cylinder operation due to cylinder-to-cylinder variations of the combustion process. The cause of cylinder-to-cylinder variations is strongly tied to non-uniform trapped mass. In particular, in-cylinder oxygen concentration plays a critical role in the combustion process of each cylinder and can be leveraged to predict combustion characteristics and to develop control algorithms that mitigate cylinder-to-cylinder variation.
Technical Paper

Efficiency Improved Combustion System for Hydrogen Direct Injection Operation

2010-10-25
2010-01-2170
This paper reports on research activities aiming to improve the efficiency of direct injected, hydrogen powered internal combustion engines. In a recent major change in the experimental setup the hydrogen single cylinder research engine at Argonne National Laboratory was upgraded to a new engine geometry providing increased compression ratio and a longer piston stroke compared to its predecessor. The higher compression ratio and the more advantageous volume to surface ratio of the combustion chamber are both intended to improve the overall efficiency of the experimental setup. Additionally, a new series of faster acting, piezo-activated injectors is used with the new engine providing increased flexibility for the optimization of DI injection strategies. This study focuses on the comparison of experimental data of the baseline versus the improved single cylinder research engine for similar engine operating conditions.
Technical Paper

Numerical and Optical Evolution of Gaseous Jets in Direct Injection Hydrogen Engines

2011-04-12
2011-01-0675
This paper performs a parametric analysis of the influence of numerical grid resolution and turbulence model on jet penetration and mixture formation in a DI-H2 ICE. The cylinder geometry is typical of passenger-car sized spark-ignited engines, with a centrally located single-hole injector nozzle. The simulation includes the intake and exhaust port geometry, in order to account for the actual flow field within the cylinder when injection of hydrogen starts. A reduced geometry is then used to focus on the mixture formation process. The numerically predicted hydrogen mole-fraction fields are compared to experimental data from quantitative laser-based imaging in a corresponding optically accessible engine. In general, the results show that with proper mesh and turbulence settings, remarkable agreement between numerical and experimental data in terms of fuel jet evolution and mixture formation can be achieved.
Technical Paper

Influence of Water Injection on Performance and Emissions of a Direct-Injection Hydrogen Research Engine

2008-10-06
2008-01-2377
The application of hydrogen (H2) as an internal combustion (IC) engine fuel has been under investigation for several decades. The favorable physical properties of hydrogen make it an excellent alternative fuel for IC engines and hence it is widely regarded as the energy carrier of the future. Direct injection of hydrogen allows optimizing this potential as it provides multiple degrees of freedom to influence the in-cylinder combustion processes and consequently engine efficiency and exhaust emissions. At certain operating conditions the stratification associated with hydrogen direct injection (DI) leads to an efficiency improvement. However, it also results in higher emissions levels. This paper examines the effects of combining an advanced direct injection strategy with water injection for efficiency benefits and emissions reduction of a hydrogen fuelled DI spark ignition (SI) engine.
Technical Paper

Prospects on Fuel Economy Improvements for Hydrogen Powered Vehicles

2008-10-06
2008-01-2378
Fuel cell vehicles are the subject of extensive research and development because of their potential for high efficiency and low emissions. Because fuel cell vehicles remain expensive and the demand for hydrogen is therefore limited, very few fueling stations are being built. To try to accelerate the development of a hydrogen economy, some original equipment manufacturers (OEM) in the automotive industry have been working on a hydrogen-fueled internal combustion engine (ICE) as an intermediate step. Despite its lower cost, the hydrogen-fueled ICE offers, for a similar amount of onboard hydrogen, a lower driving range because of its lower efficiency. This paper compares the fuel economy potential of hydrogen-fueled vehicles to their conventional gasoline counterparts. To take uncertainties into account, the current and future status of both technologies were considered.
Technical Paper

Evaluation of Injector Location and Nozzle Design in a Direct-Injection Hydrogen Research Engine

2008-06-23
2008-01-1785
The favorable physical properties of hydrogen (H2) make it an excellent alternative fuel for internal combustion (IC) engines and hence it is widely regarded as the energy carrier of the future. Hydrogen direct injection provides multiple degrees of freedom for engine optimization and influencing the in-cylinder combustion processes. This paper compares the results in the mixture formation and combustion behavior of a hydrogen direct-injected single-cylinder research engine using two different injector locations as well as various injector nozzle designs. For this study the research engine was equipped with a specially designed cylinder head that allows accommodating a hydrogen injector in a side location between the intake valves as well as in the center location adjacent to the spark plug.
Technical Paper

Efficiency and Emissions Potential of Hydrogen Internal Combustion Engine Vehicles

2011-01-19
2011-26-0003
This paper reviews and summarizes recent developments in hydrogen (H2) powered engine and vehicle research. Following an overview of mixture formation strategies, general trade-offs when operating engines on hydrogen are analyzed and highlights regarding accomplishments in efficiency improvement and emissions reduction are presented. These include estimates of efficiency potential of direct-injection hydrogen engines based on single-cylinder research engine data, fuel economy and emissions results of hydrogen powered passenger cars and pickup trucks as well as the impact and potential of hydrogen/methane blended operation.
Technical Paper

Evaluation of Ethanol Blends for Plug-In Hybrid Vehicles Using Engine in the Loop

2012-04-16
2012-01-1280
Their easy availability, lower well-to-wheel emissions, and relative ease of use with existing engine technologies have made ethanol and ethanol-gasoline blends a viable alternative to gasoline for use in spark-ignition (SI) engines. The lower energy density of ethanol and ethanol-gasoline blends, however, results in higher volumetric fuel consumption compared with gasoline. Also, the higher latent heat of vaporization can result in cold-start issues with higher-level ethanol blends. On the other hand, a higher octane number, which indicates resistance to knock and potentially enables more optimal combustion phasing, results in better engine efficiency, especially at higher loads. This paper compares the fuel consumption and emissions of two ethanol blends (E50 and E85) with those for gasoline when used in conventional (non-hybrid) and power-split-type plug-in hybrid electric vehicles (PHEVs).
Technical Paper

Impact of Blending Gasoline with Isobutanol Compared to Ethanol on Efficiency, Performance and Emissions of a Recreational Marine 4-Stroke Engine

2014-04-01
2014-01-1230
This study evaluates iso-butanol as a pathway to introduce higher levels of alternative fuels for recreational marine engine applications compared to ethanol. Butanol, a 4-carbon alcohol, has an energy density closer to gasoline than ethanol. Isobutanol at 16 vol% blend level in gasoline (iB16) exhibits energy content as well as oxygen content identical to E10. Tests with these two blends, as well as indolene as a reference fuel, were conducted on a Mercury 90 HP, 4-stroke outboard engine featuring computer controlled sequential multi-port Electronic Fuel Injection (EFI). The test matrix included full load curves as well as the 5-mode steady-state marine engine test cycle. Analysis of the full load tests suggests that equal full load performance is achieved across the engine speed band regardless of fuel at a 15-20°C increase in exhaust gas temperatures for the alcohol blends compared to indolene.
Technical Paper

Experimental Investigation of a DISI Production Engine Fuelled with Methanol, Ethanol, Butanol and ISO-Stoichiometric Alcohol Blends

2015-04-14
2015-01-0768
Stricter CO2 and emissions regulations are pushing spark ignition engines more and more towards downsizing, enabled through direct injection and turbocharging. The advantages which come with direct injection, such as increased charge density and an elevated knock resistance, are even more pronounced when using low carbon number alcohols instead of gasoline. This is mainly due to the higher heat of vaporization and the lower air-to-fuel ratio of light alcohols such as methanol, ethanol and butanol. These alcohols are also attractive alternatives to gasoline because they can be produced from renewable resources. Because they are liquid, they can be easily stored in a vehicle. In this respect, the performance and engine-out emissions (NOx, CO, HC and PM) of methanol, ethanol and butanol were examined on a 4 cylinder 2.4 DI production engine and are compared with those on neat gasoline.
Technical Paper

Air-to-Fuel Ratio Calculation Methods for Oxygenated Fuels in Two-Stroke Engines

2015-04-14
2015-01-0965
In 1990, Roy Douglas developed an analytical method to calculate the global air-to-fuel ratio of a two-stroke engine from exhaust gas emissions. While this method has considerable application to two-stroke engines, it does not permit the calculation of air-to-fuel ratios for oxygenated fuels. This study proposed modifications to the Roy Douglas method such that it can be applied to oxygenated fuels. The ISO #16183 standard, the modified Spindt method, and the Brettschneider method were used to evaluate the modifications to the Roy Douglas method. In addition, a trapped air-to-fuel ratio, appropriate for two-stroke engines, was also modified to incorporate oxygenated fuels. To validate the modified calculation method, tests were performed using a two-stroke carbureted and two-stroke direct injected marine outboard engine over a five-mode marine test cycle running indolene and low level blends of ethanol and iso-butanol fuels.
Technical Paper

Impact of Effective Compression Ratio on Gasoline-Diesel Dual-Fuel Combustion in a Heavy-Duty Engine Using Variable Valve Actuation

2015-09-01
2015-01-1796
Dual-fuel combustion using port-injected gasoline with a direct diesel injection has been shown to achieve low-temperature combustion with moderate peak pressure rise rates, low engine-out soot and NOx emissions, and high indicated thermal efficiency. A key requirement for extending high-load operation is moderating the reactivity of the premixed charge prior to the diesel injection. Reducing compression ratio, in conjunction with a higher expansion ratio using alternative valve timings, decreases compressed charge reactivity while maintain a high expansion ratio for maximum work extraction. Experimental testing was conducted on a 13L multi-cylinder heavy-duty diesel engine modified to operate dual-fuel combustion with port gasoline injection to supplement the direct diesel injection. The engine employs intake variable valve actuation (VVA) for early (EIVC) or late (LIVC) intake valve closing to yield reduced effective compression ratio.
Technical Paper

Effects of Ignition and Injection Perturbation under Lean and Dilute GDI Engine Operation

2015-09-01
2015-01-1871
Turbocharged gasoline direct injection (GDI) engines are quickly becoming more prominent in light-duty automotive applications because of their potential improvements in efficiency and fuel economy. While EGR dilute and lean operation serve as potential pathways to further improve efficiencies and emissions in GDI engines, they also pose challenges for stable engine operation. Tests were performed on a single-cylinder research engine that is representative of current automotive-style GDI engines. Baseline cases were performed under steady-state operating conditions where combustion phasing and dilution were varied to determine the effects on indicated efficiency and combustion stability. Sensitivity studies were then carried out by introducing binary low-high perturbation of spark timing and injection duration on a cycle-by-cycle basis under EGR dilute and lean operation to determine dominant feedback mechanisms.
Technical Paper

Numerical Investigation of Spark Ignition Events in Lean and Dilute Methane/Air Mixtures Using a Detailed Energy Deposition Model

2016-04-05
2016-01-0609
It is beneficial but challenging to operate spark-ignition engines under highly lean and dilute conditions. The unstable ignition behavior can result in downgraded combustion performance in engine cylinders. Numerical approach is serving as a promising tool to identify the ignition requirements by providing insight into the complex physical/chemical phenomena. An effort to simulate the early stage of flame kernel initiation in lean and dilute fuel/air mixture has been made and discussed in this paper. The simulations are set to validate against laboratory results of spark ignition behavior in a constant volume combustion vessel. In order to present a practical as well as comprehensive ignition model, the simulations are performed by taking into consideration the discharge circuit analysis, the detailed reaction mechanism, and local heat transfer between the flame kernel and spark plug.
Technical Paper

Comparison of RCCI Operation with and without EGR over the Full Operating Map of a Heavy-Duty Diesel Engine

2016-04-05
2016-01-0794
Dual-fuel combustion using port-injection of low reactivity fuel combined with direct injection of a higher reactivity fuel, otherwise known as Reactivity Controlled Compression Ignition (RCCI), has been shown as a method to achieve high efficiency combustion with moderate peak pressure rise rates, low engine-out soot and NOx emissions. A key requirement for extending to high-load operation is reduce the reactivity of the premixed charge prior to the diesel injection. One way to accomplish this is to use a very low reactivity fuel such as natural gas. In this work, experimental testing was conducted on a 13L multi-cylinder heavy-duty diesel engine modified to operate using RCCI combustion with port injection of natural gas and direct injection of diesel fuel. Natural gas/diesel RCCI engine operation is compared over the EPA Heavy-Duty 13 mode supplemental emissions test with and without EGR.
Technical Paper

Numerical Investigation of Combustion in a Lean Burn Gasoline Engine

2013-09-08
2013-24-0029
This research effort focuses on lean-burn combustion in gasoline internal combustion engines. Gasoline is largely known to be characterized by narrow flammability range, which makes the use of ultra-lean mixtures very challenging. In order to fully explore the gasoline lean burn potential, a promising strategy should combine advanced intake geometries, injection strategies, and ignition technologies. In this paper, a CFD methodology is developed in order to provide proper insight into lean-burn gasoline combustion. A baseline homogenous/lean case is analyzed and numerical results are validated against engine data. Two critical issues are addressed. First, a relatively large detailed mechanism is validated against the experimental data for extreme operating conditions (low pressure values, lean mixtures). The large cycle-to-cycle variation characterizing lean combustion is shown experimentally.
Technical Paper

Performance and Efficiency Assessment of a Production CNG Vehicle Compared to Its Gasoline Counterpart

2014-10-13
2014-01-2694
Two modern light-duty passenger vehicles were selected for chassis dynamometer testing to evaluate differences in performance end efficiency resulting from CNG and gasoline combustion in a vehicle-based context. The vehicles were chosen to be as similar as possible apart from fuel type, sharing similar test weights and identical driveline configurations. Both vehicles were tested over several chassis dynamometer driving cycles, where it was found that the CNG vehicle exhibited 3-9% lower fuel economy than the gasoline-fueled subject. Performance tests were also conducted, where the CNG vehicle's lower tractive effort capability and longer acceleration times were consistent with the lower rated torque and power of its engine as compared to the gasoline model. The vehicles were also tested using quasi-steady-state chassis dynamometer techniques, wherein a series of engine operating points were studied.
Technical Paper

Feedforward Control of Fuel Distribution on Advanced Dual-Fuel Engines with Varying Intake Valve Closing Timings

2016-10-17
2016-01-2312
This study examines the dynamics and control of an engine operated with late intake valve closure (LIVC) timings in a dual-fuel combustion mode. The engine features a fuel delivery system in which diesel is direct-injected and natural gas is port-injected. Despite the benefits of LIVC and dual-fuel strategy, combining these two techniques resulted in efficiency losses due to the variability of the combustion process across cylinders. The difference in power production across cylinders ranges from 9% at an IVC of 570°ATDC* to 38% at an IVC of 620 °ATDC and indicates an increasingly uneven fuel distribution as the intake valve remains open longer in the compression stroke. This paper describes an approach for controlling the amount of fuel injected into each cylinders’ port of an inline six- cylinder heavy-duty dual-fuel engine to minimize the variations in fuel distribution across cylinder.
Technical Paper

Hydrocarbon Speciation in Blended Gasoline-Natural Gas Operation on a Spark-Ignition Engine

2016-10-17
2016-01-2169
The high octane rating and more plentiful domestic supply of natural gas make it an excellent alternative to gasoline. Recent studies have shown that using natural gas in dual fuel engines provides one possible strategy for leveraging the advantages of both natural gas and gasoline. In particular, such engines been able to improve overall engine efficiencies and load capacity when they leverage direct injection of the natural gas fuel. While the benefits of these engine concepts are still being explored, differences in fuel composition, combustion process and in-cylinder mixing could lead to dramatically different emissions which can substantially impact the effectiveness of the engine’s exhaust aftertreatment system. In order to explore this topic, this study examined the variations in speciated hydrocarbon emissions which occur for different fuel blends of E10 and compressed natural gas and for different fuel injection strategies on a spark-ignition engine.
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