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Technical Paper

The Lean Limit and Emissions at Near-Idle for a Gasoline HAJI System with Alternative Pre-Chamber Fuels

2007-09-16
2007-24-0120
Hydrogen assisted jet ignition (HAJI) is a pre-chamber ignition system for otherwise standard gasoline fueled spark ignition engines that involves the use of a chemically active turbulent jet to initiate combustion in lean fuel mixtures. HAJI burns the lean main charge rapidly and with almost no combustion variability, which allows for low hydrocarbon emissions and almost zero NOx, due to lower peak temperatures. This paper focuses on the effects of different pre-chamber fuels on combustion stability, lean limit and emissions in a single cylinder, HAJI equipped, CFR engine under a worst case, light load condition. Results indicate that the choice of pre-chamber fuel affects the main chamber lean limit but that emissions are not largely affected before this lean limit is reached. The lean limit was extended furthest, to λ = 2.5 with hydrogen, followed by λ = 2.35 with LPG, λ = 2.25 with CNG and λ = 2.15 with carbon monoxide.
Technical Paper

The Feasibility of Downsizing a 1.25 Liter Normally Aspirated Engine to a 0.43 Liter Highly Turbocharged Engine

2007-09-16
2007-24-0083
In this paper, performance, efficiency and emission experimental results are presented from a prototype 434 cm3, highly turbocharged (TC), two cylinder engine with brake power limited to approximately 60 kW. These results are compared to current small engines found in today's automobile marketplace. A normally aspirated (NA) 1.25 liter, four cylinder, modern production engine with similar brake power output is used for comparison. Results illustrate the potential for downsized engines to significantly reduce fuel consumption while still maintaining engine performance. This has advantages in reducing vehicle running costs together with meeting tighter carbon dioxide (CO2) emission standards. Experimental results highlight the performance potential of smaller engines with intake boosting. This is demonstrated with the test engine achieving 25 bar brake mean effective pressure (BMEP).
Technical Paper

Compression Ratio Effects on Performance, Efficiency, Emissions and Combustion in a Carbureted and PFI Small Engine

2007-08-05
2007-01-3623
This paper compares the performance, efficiency, emissions and combustion parameters of a prototype two cylinder 430 cm3 engine which has been tested in a variety of normally aspirated (NA) modes with compression ratio (CR) variations. Experiments were completed using 98-RON pump gasoline with modes defined by alterations to the induction system, which included carburetion and port fuel injection (PFI). The results from this paper provide some insight into the CR effects for small NA spark ignition (SI) engines. This information provides future direction for the development of smaller engines as engine downsizing grows in popularity due to rising oil prices and recent carbon dioxide (CO2) emission regulations. Results are displayed in the engine speed, manifold absolute pressure (MAP) and CR domains, with engine speeds exceeding 10000 rev/min and CRs ranging from 9 to 13. Combustion analysis is also included, allowing mass fraction burn (MFB) comparison.
Technical Paper

Why Liquid Phase LPG Port Injection has Superior Power and Efficiency to Gas Phase Port Injection

2007-08-05
2007-01-3552
This paper reports comparative results for liquid phase versus gaseous phase port injection in a single cylinder engine. It follows previous research in a multi-cylinder engine where liquid phase was found to have advantages over gas phase at most operating conditions. Significant variations in cylinder to cylinder mixture distribution were found for both phases and leading to uncertainty in the findings. The uncertainty was avoided in this paper as in the engine used, a high speed Waukesha ASTM CFR, identical manifold conditions could be assured and MBT spark found for each fuel supply system over a wide range of mixtures. These were extended to lean burn conditions where gaseous fuelling in the multi-cylinder engine had been reported to be at least an equal performer to liquid phase. The experimental data confirm the power and efficiency advantages of liquid phase injection over gas phase injection and carburetion in multi-cylinder engine tests.
Technical Paper

Optimized Design of a Cyclic Variability Constrained Lean Limit SI Engine at Optimum NOx and Efficiency Using a PSO Algorithm

2007-08-05
2007-01-3551
In recent times new tools have emerged to aid the optimization of engine design. The particle swarm optimizer, used here is one of these tools. However, applying it to the optimization of the S.I. engine for high efficiency and low NOx emission has shown the preference of ultra lean burn strategy combined with high compression ratios. For combined power, efficiency and emissions benefits, there are two restricting factors, limiting the applicability of this strategy, knocking and cyclic variability. In the ultra lean region, knocking is not an important issue but the variability is a major concern. This paper demonstrates the application of a variability model to limit the search domain for the optimization program. The results show that variability constrains the possible gains in fuel consumption and emission reduction, through optimizing cam phasing, mixture and spark timing. The fuel consumption gain is reduced by about 11% relative.
Technical Paper

Direct Injection Compressed Natural Gas Combustion and Visualisation

2000-06-19
2000-01-1838
This paper details the development of a compressed natural gas (CNG) engine with ultra lean burn low emissions potential. Hydrogen assisted jet ignition (HAJI) is used to achieve reliable combustion and low NOx emissions, whilst direct injection is used to improve thermal efficiency and decrease hydrocarbon (HC) emissions. It is found that port inducted propane, port inducted CNG and directly injected CNG all produce negligible levels of CO and NOx when operating at air/fuel ratios higher than λ = 1.8. Furthermore, direct injection of CNG produced approximately 100 ppm C6 less HC emissions than port induction of CNG, and port induction of CNG decreased the HC emissions by around a factor of a third to a half in comparison with port induction of propane.
Technical Paper

Highly Turbocharging a Restricted, Odd Fire, Two Cylinder Small Engine - Design, Lubrication, Tuning and Control

2006-12-05
2006-01-3637
This paper describes the mechanical component design, lubrication, tuning and control aspects of a restricted, odd fire, highly turbocharged (TC) engine for Formula SAE competition. The engine was specifically designed and configured for the purpose, being a twin cylinder inline arrangement with double overhead camshafts and four valves per cylinder. Most of the engine components were specially cast or machined from billets. A detailed theoretical analysis was completed to determine engine specifications and operating conditions. Results from the analysis indicated a new engine design was necessary to sustain highly TC operation. Dry sump lubrication was implemented after initial oil surge problems were found with the wet sump system during vehicle testing. The design and development of the system is outlined, together with brake performance effects for the varying systems.
Technical Paper

Comparing the Performance and Limitations of a Downsized Formula SAE Engine in Normally Aspirated, Supercharged and Turbocharged Modes

2006-11-13
2006-32-0072
This paper compares the performance of a small two cylinder, 430 cm3 engine which has been tested in a variety of normally aspirated (NA) and forced induction modes on 98-RON pump gasoline. These modes are defined by variations in the induction system and associated compression ratio (CR) alterations needed to avoid knock and maximize volumetric efficiency (ηVOL). These modes included: (A) NA with carburetion (B) NA with port fuel injection (PFI) (C) Mildly Supercharged (SC) with PFI (D) Highly Turbocharged (TC) with PFI The results have significant relevance in defining the limitations for small downsized spark ignition (SI) engines, with power increases needed via intake boosting to compensate for the reduced swept volume. Performance is compared in the varying modes with comparisons of brake mean effective pressure (BMEP), brake power, ηVOL, brake specific fuel consumption (BSFC) and brake thermal efficiency (ηTH).
Technical Paper

Enhanced ICSI Engine Performance With Particle Swarm Optimization

2004-01-16
2004-28-0075
Increasing engine power and efficiency using a particle swarm optimization technique is investigated by using thermodynamics based quasi-steady engine simulation model. A simplified engine friction model is also incorporated to estimate the brake power output. Further, a simple knock model is used to make sure of knock free engine operation. Model is calibrated and validated to a Ford Falcon AU six-cylinder gasoline engine. Nine different engine-operating parameters are considered as input variables for the optimization; spark timing, equivalence ratio, compression ratio, inlet and exhaust vale opening timing and durations, maximum inlet valve lift and manifold pressure. Significant improvement of the engine power output for a given amount of induced gas is observed with the optimized conditions when compared to the corresponding power output with the reference engines normal operating conditions.
Technical Paper

Lean Mixture Ignition Systems for CNG in Diesel Applications

2004-01-16
2004-28-0017
A high compression ratio, single cylinder, open chamber diesel engine was converted to operate on homogenously charged compressed natural gas (CNG) with the aim of minimising pollutant emissions such as oxides of nitrogen, particulate matter and carbon dioxide. Three ignition systems were tested including spark ignition (SI), diesel pilot ignition (DPI) and hydrogen assisted jet ignition (HAJI). Irrespective of ignition system used, the efficiency of the engine operating on CNG was significantly reduced at part load compared to diesel. This was predominantly due to a greater amount of unburnt hydrocarbons, higher cycle-by-cycle variability, slow and partial burns and increased heat transfer to the walls. DPI and HAJI systems were able to extend the lean limit to lambda 2.7 and 3.3 respectively, however this did not result in efficiency gains.
Technical Paper

Comparison of Pfi and Di Superbike Engines

2008-12-02
2008-01-2943
Gasoline Direct Injection (DI) is a technique that was successful in motor sports several decades ago and is now relatively popular in passenger car applications only. DI gasoline fuel injectors have been recently improved considerably, with much higher fuel flow rates and much finer atomization enabled by the advances in fuel pressure and needle actuation. These improved injector performance and the general interest in reducing fuel consumption also in motor sports have made this option interesting again. This paper compares Port Fuel Injection (PFI) and DI of gasoline fuel in a high performance, four cylinder spark ignition engine for super bike racing. Computations are performed with a code for gas exchange, heat transfer and combustion, simulating turbulent combustion and knock.
Technical Paper

Numerical Study of a Turbocharged, Jet Ignited, Cryogenic, Port Injected, Hydrogen Engine

2009-04-20
2009-01-1425
Favorable and unfavorable properties of hydrogen as a combustion engine fuel have been accommodated in a design of a fuel efficient and clean engine providing similar to gasoline maximum torque and power. The advanced H2ICE being developed is a turbocharged engine fitted with cryogenic port hydrogen fuel injection and the hydrogen assisted jet ignition (HAJI). The combustion chamber is designed to produce a high compression ratio and therefore high thermal efficiency. A waste gated turbocharger provides pressure boosting for an increased power density running ultra lean for SULEV operation without after treatment. Thanks to the combustion properties of hydrogen further enhanced by the HAJI system, the engine load is mainly controlled throttle-less decreasing the fuel-to-air equivalence ratio from ultra lean ϕ=0.43 to ultra-ultra lean ϕ=0.18. The computational model developed for addressing the major design issues and the predicted engine performance and efficiency maps are included.
Technical Paper

Modeling Alternative Prechamber Fuels in Jet Assisted Ignition of Gasoline and LPG

2009-04-20
2009-01-0721
Gas assisted jet ignition is a prechamber combustion initiation system for conventional spark ignition engines. With the system, a chemically active turbulent jet is used to initiate combustion in lean fuel mixtures enabling reliable combustion over a much broader range of air-fuel ratios. The extended range is due to the distributed ignition source provided by the jet, which can overcome the problems of poorly mixed main chamber charges and slower burning fuels. In addition, the ability to reliably ignite lean mixtures improves the thermal efficiency and enables ultra low emission levels. Experiments together with flame propagation modeling completed using STAR-CD with CHEMKIN Kinetics were done in order to examine the effects of numerous prechamber fuels on the ignition of the main fuel, which consisted of either liquefied petroleum gas (LPG) or gasoline.
Technical Paper

Development of a 430cc Constant Power Engine for FSAE Competition

2006-04-03
2006-01-0745
This paper describes the design and development of an engine with constant power for SAE's student Formula race-car competition, allowing the avoidance of gear shifting for much of the Autocross event. To achieve constant power for over 50% of the speed range, turbocharging was adopted with a boost pressure ratio of 2.8 at mid-range speeds and applied to an engine capacity of 430 cc. This engine was specifically designed and configured for the purpose, being a twin cylinder in-line arrangement with double overhead camshafts. Most of the engine components were specially cast or machined from billets. The capacity was selected to minimise frictional losses and thus increase delivered power along with dry sump lubrication and a three speed gear box. The engine manifolds and plenums were designed using a CAE application and proved to be well suited to the task resulting in excellent agreement between predicted and actual performance.
Technical Paper

Joint Efficiency and NOx Optimization Using a PSO Algorithm

2006-04-03
2006-01-1109
The challenge of tough fuel consumption reduction targets and near zero NOx emission standards can be met by optimization of the full range of engine design variables. Here these are explored through an engine simulation model and the application of an optimizing algorithm that can work in discontinuous data space. The combustion model has main features that include flame propagation, the effects of turbulence, chamber shape interaction and NOx formation. Two engine configurations are used to illustrate the application of the model and optimizer. Both allow the adoption of extra lean burn possible with LPG as fuel and EGR through an external route or cam phasing. In the first the compression ratio and cam profiles are fixed, in the second study they are also optimized.
Technical Paper

The Systematic Evaluation of Twelve LP Gas Fuels for Emissions and Fuel Consumption

2000-06-19
2000-01-1867
The effects on bi-fuel car exhaust emissions, fuel consumption and acceleration performance of a range of LPG fuels has been determined. The LPGs tested included those representing natural gas condensate and oil refineries' products to include a spectrum of C3:C4 and paraffiinic:olefinic mixtures. The overall conclusions are that exhaust emissions from the gaseous fuels for the three-way catalyst equipped cars tested were lower than for gasoline. For all the LPGs, CO2 equivalent emissions are reduced by 7% to 10% or more compared with gasoline. The cars' acceleration performance indicates that there was no sacrifice in acceleration times to various speeds, with any gaseous fuel in these OEM developed cars.
Journal Article

4 L Light Duty LPG Engine Evaluated for Heavy Duty Application

2010-05-05
2010-01-1463
Many applications of liquefied petroleum gas (LPG) to commercial vehicles have used their corresponding diesel engine counterparts for their basic architecture. Here a review is made of the application to commercial vehicle operation of a robust 4 L, light-duty, 6-cylinder in-line engine produced by Ford Australia on a unique long-term production line. Since 2000 it has had a dedicated LPG pick-up truck and cab-chassis variant. A sequence of research programs has focused on optimizing this engine for low carbon dioxide (CO₂) emissions. Best results (from steady state engine maps) suggest reductions in CO₂ emissions of over 30% are possible in New European Drive Cycle (NEDC) light-duty tests compared with the base gasoline engine counterpart. This has been achieved through increasing compression ratio to 12, running lean burn (to λ = 1.6) and careful study (through CFD and bench tests) of the injected LPG-air mixing system.
Journal Article

Combustion System Development and Analysis of a Downsized Highly Turbocharged PFI Small Engine

2010-09-28
2010-32-0093
This paper provides some insight into the future direction for developing smaller capacity downsized engines, which will be needed to meet tight CO₂ targets and the world's future powertrain requirements. This paper focuses on the combustion system development and combustion analysis results for a downsized 0.43-liter highly turbocharged engine. The inline two-cylinder engine used in experiments was specifically designed and constructed to enable 25 bar BMEP. Producing this specific output is one way forward for future passenger vehicle powertrains, enabling in excess of 50% swept capacity reduction whilst maintaining comparable vehicle performance. Previous experiments and analysis have found that the extent to which larger engines can be downsized while still maintaining equal performance is combustion limited.
Technical Paper

A Before and After Study of the Change to Unleaded Gasoline-Test Results from EPA and Other Cycles

1990-02-01
900150
A fleet of 50, 1986-1987 model year cars designed for unleaded gasoline has been tested on the road and on a chassis dynamometer over 5 driving cycles and a wide range of other manoeuvres including steady speeds. It was found that the fuel consumption of this fleet was 17 to 23% (depending on test cycle) less than that of a corresponding fleet to leaded fuelled cars of 1980 model year average. Exhaust emissions were significantly lowered in the range of 45 to 93%. However trend line analysis of the several data sets indicates that the ULG fleet has about 6% higher fuel consumption than would have been expected if there had been a continuing evolution of leaded vehicle technology. The data base produced has applicability to a wide range of planning and design tasks, and those illustrated indicate the effects of speed limit changes and advisory speed signs on fuel consumption and emissions.
Technical Paper

Effects of a Wide Range of Drive Cycles on the Emissions from Vehicles of Three Levels of Technology

1995-02-01
950221
Exhaust emission tests were performed on a fleet of vehicles comprising a range of engine technology from leaded fuel control methods to closed loop three-way catalyst meeting 1992 U.S. standards but marketed in Australia. Each vehicle was tested to 5 different driving cycles including the FTP cycles and steady speed driving. Research had shown that for hot-start operation the major driving pattern parameters which influence fuel consumption and exhaust emissions are average speed and PKE (the positive acceleration kinetic energy per unit distance). Plots from analysis of micro-trip fuel use and emissions rates from the test cycles may be presented as contours in PKE. It follows that the micro trip emissions from a range of driving cycles including, regulated e.g. FTP city and unregulated e.g. LA-92, recently developed EPA cycles or from other cities e.g. Bangkok can be superimposed.
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