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Technical Paper

On-Board Fuel Property Classifier for Fuel Property Adaptive Engine Control System

2006-04-03
2006-01-0054
This paper explores the possibility of on-board fuel classification for fuel property adaptive compression-ignition engine control system. The fuel classifier is designed to on-board classify the fuel that a diesel engine is running, including alternative and renewable fuels such as bio-diesel. Based on this classification, the key fuel properties are provided to the engine control system for optimal control of in-cylinder combustion and exhaust treatment system management with respect to the fuel. The fuel classifier employs engine input-output response characteristics measured from standard engine sensors to classify the fuel. For proof-of-concept purposes, engine input-output responses were measured for three different fuels at three different engine operating conditions. Two neural-network-based fuel classifiers were developed for different classification scenarios. Of the three engine operating conditions tested, two conditions were selected for the fuel classifier to be active.
Technical Paper

Heavy-Duty Diesel Engine Emissions Tests Using Special Biodiesel Fuels

2005-10-24
2005-01-3671
A 2003 heavy-duty diesel engine (2002 emissions level) was used to test a representative biodiesel fuel as well as the methyl esters of several different fatty acids. The fuel variables included degree of saturation, the oxygen content, and carbon chain length. In addition, two pure normal paraffins with the corresponding chain lengths of two of the methyl esters were also tested to determine the impact of chain length. The dependent variables were the NOx and the particulate emissions (PM). The results indicated that the primary fuel variable affecting the emissions is the oxygen content. The emissions results showed that the highest oxygen content test fuel had the lowest emissions of both NOx and PM. As compared to the baseline diesel fuel the NOx emissions were reduced by 5 percent and the PM emissions were reduced by 83 percent.
Technical Paper

Performance Predictions for High Efficiency Stoichiometric Spark Ignited Engines

2005-04-11
2005-01-0995
Southwest Research Institute (SwRI) is exploring the feasibility of extending the performance and fuel efficiency of the spark ignition (SI) engine to match that of the emission constrained compression (CI) engine, whilst retaining the cost effective 3-way stoichiometric aftertreatment systems associated with traditional SI light duty engines. The engine concept, which has a relatively high compression ratio and uses heavy EGR, is called “HEDGE”, i.e. High Efficiency Durable Gasoline Engine. Whereas previous SwRI papers have been medium and heavy duty development focused, this paper uses results from simulations, with some test bed correlations, to predict multicylinder torque curves, brake thermal efficiency and NOx emissions as well as knock limit for light and medium duty applications.
Technical Paper

The Heavy Duty Gasoline Engine - A Multi-Cylinder Study of a High Efficiency, Low Emission Technology

2005-04-11
2005-01-1135
SwRI has developed a new technology concept involving the use of high EGR rates coupled with a high-energy ignition system in a gasoline engine to improve fuel economy and emissions. Based on a single-cylinder study [1], this study extends the concept of a high compression ratio gasoline engine with EGR rates > 30% and a high-energy ignition system to a multi-cylinder engine. A 2000 MY Isuzu Duramax 6.6 L 8-cylinder engine was converted to run on gasoline with a diesel pilot ignition system. The engine was run at two compression ratios, 17.5:1 and 12.5:1 and with two different EGR systems - a low-pressure loop and a high pressure loop. A high cetane number (CN) diesel fuel (CN=76) was used as the ignition source and two different octane number (ON) gasolines were investigated - a pump grade 91 ON ((R+M)/2) and a 103 ON ((R+M)/2) racing fuel.
Technical Paper

HCCI in a Variable Compression Ratio Engine-Effects of Engine Variables

2004-06-08
2004-01-1971
Homogeneous Charge Compression Ignition (HCCI) experiments were performed in a variable compression ratio single cylinder engine. This is the fourth paper resulting from work performed at Southwest Research Institute in this HCCI engine. The experimental variables, in addition to speed and load, included compression ratio, EGR level, intake manifold pressure and temperature, fuel introduction location, and fuel composition. Mixture preparation and start of reaction control were identified as fundamental problems that required non-traditional mixture preparation and control strategies. The effects of the independent variable on the start of reaction have been documented. For fuels that display significant pre-flame reactions, the start of the pre-flame reactions is controlled primarily by the selection of the fuel and the temperature history of the fuel air mixture.
Technical Paper

The Heavy-Duty Gasoline Engine - An Alternative to Meet Emissions Standards of Tomorrow

2004-03-08
2004-01-0984
A technology path has been identified for development of a high efficiency, durable, gasoline engine, targeted at achieving performance and emissions levels necessary to meet heavy-duty, on-road standards of the foreseeable future. Initial experimental and numerical results for the proposed technology concept are presented. This work summarizes internal research efforts conducted at Southwest Research Institute. An alternative combustion system has been numerically and experimentally examined. The engine utilizes gasoline as the fuel, with a combination of enabling technologies to provide high efficiency operation at ultra-low emissions levels. The concept is based upon very highly-dilute combustion of gasoline at high compression ratio and boost levels. Results from the experimental program have demonstrated engine-out NOx emissions of 0.06 g/hp/hr, at single-cylinder brake thermal efficiencies (BTE) above thirty-four percent.
Technical Paper

Effects of Water-Fuel Emulsions on Spray and Combustion Processes in a Heavy-Duty DI Diesel Engine

2002-10-21
2002-01-2892
Significant reductions of particulate matter (PM) and nitrogen oxides (NOx) emissions from diesel engines have been realized through fueling with water-fuel emulsions. However, the physical and chemical in-cylinder mechanisms that affect these pollutant reductions are not well understood. To address this issue, laser-based and chemiluminescence imaging experiments were performed in an optically-accessible, heavy-duty diesel engine using both a standard diesel fuel (D2) and an emulsion of 20% water, by mass (W20). A laser-based Mie-scatter diagnostic was used to measure the liquid-phase fuel penetration and showed 40-70% greater maximum liquid lengths with W20 at the operating conditions tested. At some conditions with low charge temperature or density, the liquid phase fuel may impinge directly on in-cylinder surfaces, leading to increased PM, HC, and CO emissions because of poor mixing.
Technical Paper

Effects of PuriNOx™ Water-Diesel Fuel Emulsions on Emissions and Fuel Economy in a Heavy-Duty Diesel Engine

2002-10-21
2002-01-2891
The engine-out emissions and fuel consumption rates for a modern, heavy-duty diesel engine were compared when fueling with a conventional diesel fuel and three water-blend-fuel emulsions. Four different fuels were studied: (1) a conventional diesel fuel, (2) PuriNOx,™ a water-fuel emulsion using the same conventional diesel fuel, but having 20% water by mass, and (3,4) two other formulations of the PuriNOx™ fuel that contained proprietary chemical additives intended to improve combustion efficiency and emissions characteristics. The emissions data were acquired with three different injection-timing strategies using the AVL 8-Mode steady-state test method in a Caterpillar 3176 engine, which had a calibration that met the 1998 nitrogen oxides (NOX) emissions standard.
Technical Paper

Partial Pre-Mixed Combustion with Cooled and Uncooled EGR in a Heavy-Duty Diesel Engine

2002-03-04
2002-01-0963
An experimental investigation of the effects of partial premixed charge compression ignition (PCCI) combustion and EGR temperature was conducted on a Caterpillar C-12 heavy-duty diesel engine (HDDE). The addition of EGR and PCCI combustion resulted in significant NOx reductions over the AVL 8-mode test. The lowest weighted BSNOx achieved was 2.55 g/kW-hr (1.90 g/hp-hr) using cooled EGR and 20% port fuel injection (PFI). This represents a 54% reduction compared to the stock engine. BSHC and BSCO emissions increased by a factor of 8 and 10, respectively, compared to the stock engine. BSFC also increased by 7.7%. In general, BSHC, BSCO, BSPM, and BSFC increased linearly with the amount of port-injected fuel.
Technical Paper

HCCI Operation of a Dual-Fuel Natural Gas Engine for Improved Fuel Efficiency and Ultra-Low NOx Emissions at Low to Moderate Engine Loads

2001-05-07
2001-01-1897
A new combustion concept has been developed and tested for improving the low to moderate load efficiency and NOx emissions of natural gas engines. This concept involves operation of a dual-fuel natural gas engine on Homogeneous Charge Compression Ignition (HCCI) in the load regime of idle up to 35 % of the peak torque. A dual-fuel approach is used to control the combustion phasing of the engine during HCCI operation, and conventional spark-ignited natural gas combustion is used for the high-load regime. This concept has resulted in an engine with power output and high-load fuel efficiency that are unchanged from the base engine, but with a 10 - 15 % improvement to the low to moderate load fuel efficiency. In addition, the engine-out NOx emissions during HCCI operation are over 90% lower than on spark-ignited natural gas operation over the equivalent load range.
Technical Paper

EPA HDEWG Program - Test Fuel Development

2000-06-19
2000-01-1857
In 1995, US Environmental Protection Agency (EPA) formed the Heavy-Duty Engine Working Group (HDEWG). The objective of the group was to assess the role diesel fuel could play in meeting exhaust emission standards proposed for model year 2004+ heavy-duty diesel engines. The group developed a three-phase program to achieve this objective. This paper describes the development of test fuels used in Phase 2 of the EPA HDEWG Program to investigate the effect of fuel properties on heavy-duty diesel engine emissions. It discusses the design of the fuel matrix, reviews the process of test fuel preparation and presents the results of a multi-laboratory fuel analysis program. Fuel properties selected for investigation included density, cetane number, mono- and polyaromatic hydrocarbon content.
Technical Paper

EPA HDEWG Program-Engine Tests Results

2000-06-19
2000-01-1858
In 1997 the US EPA formed a Heavy-Duty Engine Working Group (HDEWG) in the Mobile Sources Technical Advisory Subcommittee to address the questions related to fuel property effects on heavy-duty diesel engine emissions. The Working Group consisted of members from EPA and the oil refining and engine manufacturing industries. The goal of the Working Group was to help define the role of the fuel in meeting the future emissions standards in advanced technology engines (beyond 2004 regulated emissions levels). To meet this objective a three-phase program was developed. Phase I was designed to demonstrate that a prototype engine, located at Southwest Research Institute, represented similar emissions characteristics to that of certain manufacturers prototype engines. Phase II was designed to document the effects of selected fuel properties using a statistically designed fuel matrix in which cetane number, density, and aromatic content and type were the independent variables.
Technical Paper

EPA HDEWG Program - Statistical Analysis

2000-06-19
2000-01-1859
The U.S. Environmental Protection Agency (EPA) formed a Heavy-Duty Engine Working Group (HDEWG) in the Mobile Sources Technical Advisory Subcommittee in 1995. The goal of the HDEWG was to help define the role of the fuel in meeting the future emissions standards in advanced technology engines (beyond 2004 regulated emissions levels). A three-phase program was developed. This paper presents the results of the statistical analysis of the data collected in the Phase II program. Included is a description of the design of the fuel test matrix, and a listing of the regression equations developed to predict emissions as a function of fuel density, cetane number, monoaromatics, and polyaromatics. Also included is a description of selected analyses of the emissions from a smaller set of fuel data that allowed direct comparison of the effects of natural and boosted cetane number.
Technical Paper

Effects of Exhaust Gas Recirculation on the Degradation Rates of Lubricating Oil in a Heavy-Duty Diesel Engine

1999-10-25
1999-01-3574
The specific goal of this project was to determine if there is a difference in the lube oil degradation rates in a heavy-duty diesel engine equipped with an EGR system, as compared to the same configuration of the engine, but minus the EGR system. A secondary goal was to develop FTIR analysis of used lube oil as a sensitive technique for rapid evaluation of the degradation properties of lubricants. The test engine selected for this work was a Caterpillar 3176 engine. Two engine configurations were used, a standard 1994 design and a 1994 configuration with EGR designed to meet the 2004 emissions standards. The most significant changes in the lubricant occurred during the first 50-100 hours of operation. The results clearly demonstrated that the use of EGR has a significant impact on the degradation of the engine lubricant.
Technical Paper

The Effects of Fuel Properties on Emissions from a 2.5gm NOx Heavy-Duty Diesel Engine

1998-10-19
982491
The engine selected for this work was a Caterpillar 3176 engine. Engine exhaust emissions, performance, and heat release rates were measured as functions of engine configuration, engine speed and load. Two engine configurations were used, a standard 1994 design and a 1994 configuration with EGR designed to achieve a NOx emissions level of 2.5 gm/hp-hr. Measurements were performed at 7 different steady-state, speed-load conditions on thirteen different test fuels. The fuel matrix was statistically designed to independently examine the effects of the targeted fuel properties. Cetane number was varied from 40 to 55, using both natural cetane number and cetane percent improver additives. Aromatic content ranged from 10 to 30 percent in two different forms, one in which the aromatics were predominantly mono-aromatic species and the other, where a significant fraction of the aromatics were either di- or tri-aromatics.
Technical Paper

Nox Control in Heavy-Duty Diesel Engines - What is the Limit?

1998-02-23
980174
Methods to reduce direct injected diesel engine emissions in the combustion chamber will be discussed in this paper. The following NOx emission reduction technologies will be reviewed: charge air chilling, water injection, and exhaust gas recirculation (EGR). Emphasis will be placed on the development of an EGR system and the effect of EGR on NOx and particulates. The lower limit of NOx that can be obtained using conventional diesel engine combustion will be discussed. Further reductions in NOx may require changing the combustion process from a diffusion flame to a homogeneous charge combustion system.
Technical Paper

Cetane Numbers of Fatty Compounds:Influence of Compound Structure and of Various Potential Cetane Improvers

1997-05-01
971681
Biodiesel is a mixture of esters (usually methyl esters) of fatty acids found in the triglycerides of vegetable oils. The different fatty compounds comprising biodiesel possess different ignition properties. To investigate and potentially improve these properties, the cetane numbers of various fatty acids and esters were determined in a Constant Volume Combustion Apparatus. The cetane numbers range from 20.4 for linolenic acid to 80.1 for butyl stearate. The cetane numbers depend on the number of CH2 groups as well as the number of double bonds and other factors. Various oxygenated compounds were studied for their potential of improving the cetane numbers of fatty compounds. Several potential cetane improvers with ignition delay properties giving calculated cetane numbers over 100 were identified. The effect of these cetane improvers depended on their concentration and also on the fatty material investigated.
Technical Paper

Homogeneous Charge Compression Ignition of Diesel Fuel

1996-05-01
961160
A single-cylinder, direct-injection diesel engine was modified to operate on compression ignition of homogenous mixtures of diesel fuel and air. Previous work has indicated that extremely low emissions and high efficiencies are possible if ignition of homogeneous fuel-air mixtures is accomplished. The limitations of this approach were reported to be misfire and knock. These same observations were verified in the current work. The variables examined in this study included air-fuel ratio, compression ratio, fresh intake air temperature, exhaust gas recirculation rate, and intake mixture temperatures. The results suggested that controlled homogeneous charge compression ignition (HCCI) is possible. Compression ratio, EGR rate, and air fuel ratio are the practical controlling factors in achieving satisfactory operation. It was found that satisfactory power settings are possible with high EGR rates and stoichiometric fuel-air mixtures.
Technical Paper

Coal-Water-Slurry Autoignition in a High-Speed Detroit Diesel Engine

1994-10-01
941907
Autoignition of coal-water-slurry (CWS) fuel in a two-stroke engine operating at 1900 RPM has been achieved. A Pump-Line-Nozzle (PLN) injection system, delivering 400mm3/injection of CWS, was installed in one modified cylinder of a Detroit Diesel Corporation (DI)C) 8V-149TI engine, while the other seven cylinders remained configured for diesel fuel. Coal Combustion was sustained by maintaining high gas and surface temperatures with a combination of hot residual gases, warm inlet air admission, ceramic insulated components and increased compression ratio. The coal-fueled cylinder generated 85kW indicated power (80 percent of rated power), and lower NOx levels with a combustion efficiency of 99.2 percent.
Technical Paper

Injection Pressure and Intake Air Density Effects on Ignition and Combustion in a 4-Valve Diesel Engine

1994-10-01
941919
Diesel engine optimization for low emissions and high efficiency involves the use of very high injection pressures. It was generally thought that increased injection pressures lead to improved fuel air mixing due to increased atomization in the fuel jet. Injection experiments in a high-pressure, high-temperature flow reactor indicated, however, that high injection pressures, in excess of 150 MPa, leads to greatly increased penetration rates and significant wall impingement. An endoscope system was used to obtain movies of combustion in a modern, 4-valve, heavy-duty diesel engine. Movies were obtained at different speeds, loads, injection pressures, and intake air pressures. The movies indicated that high injection pressure, coupled with high intake air density leads to very short ignition delay times, ignition close to the nozzle, and burning of the plumes as they traverse the combustion chamber.
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