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A program has been completed to evaluate ultra-low sulfur diesel fuels and passive diesel particulate filters (DPFs) in truck and bus fleets operating in southern California. The fuels, ECD and ECD-1, are produced by ARCO (a BP Company) and have less than 15 ppm sulfur content. Vehicles were retrofitted with two types of catalyzed DPFs, and operated on ultra-low sulfur diesel fuel for over one year. Exhaust emissions, fuel economy and operating cost data were collected for the test vehicles, and compared with baseline control vehicles. Regulated emissions are presented from two rounds of tests. The first round emissions tests were conducted shortly after the vehicles were retrofitted with the DPFs. The second round emissions tests were conducted following approximately one year of operation. Several of the vehicles retrofitted with DPFs accumulated well over 100,000 miles of operation between test rounds.

As connected and automated vehicle technologies emerge and proliferate, lower frequency vehicle trajectory data is becoming more widely available. In some cases, entire fleets are streaming position, speed, and telemetry at sample rates of less than 10 seconds. This presents opportunities to apply powertrain simulators such as the National Renewable Energy Laboratory’s Future Automotive Systems Technology Simulator to model how advanced powertrain technologies would perform in the real world. However, connected vehicle data tends to be available at lower temporal frequencies than the 1-10 Hz trajectories that have typically been used for powertrain simulation. Higher frequency data, typically used for simulation, is costly to collect and store and therefore is often limited in density and geography. This paper explores the suitability of lower frequency, high availability, connected vehicle data for detailed powertrain simulation.

Delivery of a lubricant as a vapor mixed with a carrier gas provides a method of controlling the delivery rate of the lubricant. Temperatures in the range of 370 to 800 C are high enough to produce a lubricating film from tricresyl phosphate [TCP] vapor delivered in nitrogen as a carrier gas. The solid film lubricant formed by this delivery system provides excellent lubrication for a four-ball wear tester run at 370 °C. Deposit rates are compared for TCP vapor delivered lubrication over a temperature range using stainless steel and quartz surfaces. The deposit rate is sensitive to TCP concentration in the carrier gas. The deposit rates of the TCP decomposition products versus time are reported. Having been demonstrated in laboratory tests, the Vapor Phase [VP] concept is being pursued for hot section lubrication of the advanced (low heat rejection) diesel engines.

Two advanced combustion models have been validated with the KIVA-3V Release 2 code in the context of two-stage combustion in a heavy duty diesel engine. The first model uses CHEMKIN to directly integrate chemistry in each computational cell. The second model accounts for flame propagation with the G-equation, and CHEMKIN predicts autoignition and handles chemistry ahead of and behind the flame front. A Damköhler number criterion was used in flame containing cells to characterize the local mixing status and determine whether heat release and species change should be a result of flame propagation or volumetric heat release. The purpose of this criterion is to make use of physical and chemical time scales to determine the most appropriate chemistry model, depending on the mixture composition and thermodynamic properties of the gas in each computational cell.

The heavy-duty diesel engine industry is required to meet stringent emission standards. There is also the demand for more fuel efficient engines by the customer. In a previous study on an engine with variable intake valve closure timing, the authors found that an early single injection and accompanying premixed charge compression ignition (PCCI) combustion provides advantages in emissions and fuel economy; however, unacceptably high peak pressures and rates of pressure-rise impose a severe operating constraint. The use of a Pressure Reactive Piston assembly (PRP) as a means to limit peak pressures is explored in the present work. The concept is applied to a heavy-duty diesel engine and genetic algorithms (GA) are used in conjunction with the multi-dimensional engine simulation code KIVA-3V to provide an optimized set of operating variables.

The goal of this project was to demonstrate a low emissions, high efficiency heavy-duty on-highway natural gas engine. The emissions targets for this project are to demonstrate US 2010 emissions standards on the 13-mode steady state test. To meet this goal, a chemically correct combustion (stoichiometric) natural gas engine with exhaust gas recirculation (EGR) and a three way catalyst (TWC) was developed. In addition, a Sturman Industries, Inc. camless Hydraulic Valve Actuation (HVA) system was used to improve efficiency. A Volvo 11 liter diesel engine was converted to operate as a stoichiometric natural gas engine. Operating a natural gas engine with stoichiometric combustion allows for the effective use of a TWC, which can simultaneously oxidize hydrocarbons and carbon monoxide and reduce NOx. High conversion efficiencies are possible through proper control of air-fuel ratio.

The key hurdles to achieving wide consumer acceptance of battery electric vehicles (BEVs) are weather-dependent drive range, higher cost, and limited battery life. These translate into a strong need to reduce a significant energy drain and resulting drive range loss due to auxiliary electrical loads the predominant of which is the cabin thermal management load. Studies have shown that thermal sub-system loads can reduce the drive range by as much as 45% under ambient temperatures below −10 °C. Often, cabin heating relies purely on positive temperature coefficient (PTC) resistive heating, contributing to a significant range loss. Reducing this range loss may improve consumer acceptance of BEVs. The authors present a unified thermal management system (UTEMPRA) that satisfies diverse thermal and design needs of the auxiliary loads in BEVs.

Due to its high efficiency and superior durability the diesel engine is again becoming a prime candidate for future light-duty vehicle applications within the United States. While in Europe the overall diesel share exceeds 40%, the current diesel share in the U.S. is 1%. Despite the current situation and the very stringent Tier 2 emission standards, efforts are being made to introduce the diesel engine back into the U.S. market. In order to succeed, these vehicles have to comply with emissions standards over a 120,000 miles distance while maintaining their excellent fuel economy. The availability of technologies such as high-pressure common-rail fuel systems, low sulfur diesel fuel, NOx adsorber catalysts (NAC), and diesel particle filters (DPFs) allow the development of powertrain systems that have the potential to comply with the light-duty Tier 2 emission requirements. In support of this, the U.S.

The effectiveness of scavenging, the displacement of residual combustion gases with fresh air, is examined in an advanced, high power-density diesel engine, consisting of a two-stroke, opposed-piston reciprocator with an ultra-high boost. KIVA-3, a three-dimensional code for modeling reactive flows with fuel injection, is used to study the effect of a variety design choices on scavenging. The parametric study includes the inclined angle of the intake ports, the exhaust port timing and size and the piston stroke-to-bore ratio. A baseline geometry of the opposed-piston engine is examined in detail, which models an existing mono-cylinder test rig. The baseline-design exhibits large asymmetries, nonsteady flow and large recirculation regions that degrade the scavenging. Significant improvement in the scavenging of the baseline design is observed with a uniform inclined angle of the inlet ports of about 20° and with a larger stroke-to-bore ratio (2.0 compared with 1.08).

This paper is a continuation of an earlier paper, which examined the steady-state internal heat transfer in the exhaust system of a diesel powered, light-duty vehicle. The present paper deals with the heat transfer of the exhaust system during two types of transient testing, as well as, the estimation of the exhaust systems external heat transfer. Transient heat transfer was evaluated using: a simple fuel-step transient under constant speed and the New European Driving Cycle (NEDC). The thermal response of the external walls varied considerably for the various components of the exhaust system. The largest percent difference between the measured temperatures and the corresponding quasi-steady estimates were about 10%, which is attributed to thermal storage. Allowing for thermal storage resulted in an excellent agreement between measurements and analysis.

A numerical study of the effects of injection parameters and operating conditions for diesel-fuel HCCI operation is presented with consideration of Variable Geometry Sprays (VGS). Methods of mixture preparation are explored that overcome one of the major problems in HCCI engine operation with diesel fuel and conventional direct injection systems, i.e., fuel loss due to wall impingement and the resulting unburned fuel. Low pressure injection of hollow cone sprays into the cylinder of a production engine with the spray cone angle changing during the injection period were simulated using the multi-dimensional KIVA-3V CFD code with detailed chemistry. Variation of the starting and ending spray angles, injection timing, initial cylinder pressure and temperature, swirl intensity, and compression ratio were explored. As a simplified case of VGS, two-pulse, hollow-cone sprays were also simulated.

Multidimensional models require physical inputs about the engine operating conditions. This paper explores the effects of unavoidable experimental uncertainties in the specification of important parameters such as the start of injection, duration of injection, amount of fuel injected per cycle, gas temperature at IVC, and the spray nozzle hole diameter. The study was conducted for a Caterpillar 3401 heavy-duty diesel engine for which extensive experimental data is available. The engine operating conditions include operation at high and low loads, with single and double injections. The computations were performed using a modified version of the KIVA3V code. Initially the model was calibrated to give very good agreement with experimental data in terms of trends and also to a lesser degree in absolute values, over a range of operating conditions and injection timings.

In this paper, researchers at the National Renewable Energy Laboratory present the results of simulation studies to evaluate potential fuel savings as a result of improvements to vehicle rolling resistance, coefficient of drag, and vehicle weight as well as hybridization for four powertrains for medium-duty parcel delivery vehicles. The vehicles will be modeled and simulated over 1,290 real-world driving trips to determine the fuel savings potential based on improvements to each technology and to identify best use cases for each platform. The results of impacts of new technologies on fuel saving will be presented, and the most favorable driving routes on which to adopt them will be explored.

The effects of residual gas mixing were studied in a single-cylinder, air-cooled utility engine using both external exhaust gas recirculation (EGR) and internal residual retention. EGR was introduced far upstream of the throttle to ensure proper mixing. Internal residual was changed by varying the length of the valve overlap period. EGR was measured in the intake system; the total in-cylinder diluent was directly measured using a skip-fire, cylinder dumping technique. A sweep of diluent fraction was performed at different engine speeds, engine loads, fuel mixture preparation systems, and ignition timings. An optimum level of diluent, where the combined hydrocarbon and NOx emissions were minimal, was found to exist for each operating condition. Higher levels of diluent, either through internal retention or external recirculation, caused the combined emissions to increase.

Detroit Diesel Corporation (DDC) is developing the DELTA 4.0L V6 engine, specifically for the North American light truck market. This market poses unique requirements for a diesel engine, necessitating a clean sheet engine design. DELTA was developed from a clean sheet of paper, with the first engine firing just 228 days later. The process began with a Quality Function Deployment (QFD) analysis, which prioritized the development criteria. The development process integrated a co-located, fully cross-functional team. Suppl iers were fully integrated and maintained on-site representation. The first demonstration vehicle moved under its own power 12 weeks after the first engine fired. It was demonstrated to the automotive press 18 days later. DELTA has repeatedly demonstrated its ability to disprove historical North American diesel perceptions and compete directly with gasoline engines. This paper outlines the Generation 0.0 development process and briefly defines the engine.

Gasoline fueled Homogeneous Charge Compression Ignition (HCCI) combustion with internal exhaust gas re-circulation using Negative Valve Overlap (NOL) was investigated by means of calculation and experiment in order to apply this technology to practical use with sufficient operating range and with acceptable emission and fuel consumption. In this paper we discuss the basic characteristics of NOL-HCCI with emphasis on the influence of intake valve timing on load range, residual gas fraction and induction air flow rate. Emission and fuel consumption under various operation conditions are also discussed. A water-cooled 250cc single cylinder engine with a direct injection system was used for this study. Three sets of valve timing were selected to investigate the effect of intake valve opening duration. Experimental results demonstrated that an engine speed of approximately 2000rpm yields an NMEP (Net Mean Effective Pressure) range from 200kPa to 400kPa.

Engine design is a time consuming process in which many costly experimental tests are usually conducted. With increasing prediction ability of engine simulation tools, engine design aided by CFD software is being given more attention by both industry and academia. It is also of much interest to be able to use design information gained from an existing engine design of one size in the design of engines of other sizes to reduce design time and costs. Therefore it is important to study size-scaling relationships for engines over wide range of operating conditions. This paper presents CFD studies conducted for two production diesel engines - a light-duty GM-Fiat engine (0.5L displacement) and a heavy-duty Caterpillar engine (2.5L displacement). Previously developed scaling arguments, including an equal spray penetration scaling model and an extended, equal flame lift-off length scaling model were employed to explore the parametric scaling connections between the two engines.

Measurements of the instantaneous heat flux at three positions on the cylinder head surface, and the steady-state cylinder head temperatures at four positions on the cylinder head have been obtained. Engine tests were performed for a range of air-fuel ratios including regimes rich of stoichiometric, stoichiometric, and lean of stoichiometric. In addition, ignition timing was advanced in increments from 22° BTDC to 40° BTDC. All tests were run with the throttle either fixed in the wide open position, or fixed in a position that produced 75% of the maximum power with the standard ignition timing and an air-fuel ratio of 13.5. This was done to ensure that changes in air mass flow rate were not influencing the results. In addition, all tests were performed with a fuel mixture preparation being provided by system designed to deliver a homogeneous premixed charge to the inlet port. This was done to ensure that mixture preparation issues were not confounding the results.

A combustion chamber geometry design optimization study has been performed on a high-speed direct-injection (HSDI) automotive diesel engine at a part-load medium-speed operating condition using both modeling and experiments. A model-based optimization was performed using the KIVA-GA code. This work utilized a newly developed 6-parameter automated grid generation technique that allowed a vast number of piston geometries to be considered during the optimization. Other salient parameters were included that are known to have an interaction with the chamber geometry. They included the start of injection (SOI) timing, swirl ratio (SR), exhaust gas recirculation percentage (EGR), injection pressure, and the compression ratio (CR). The measure of design fitness used included NOx, soot, unburned hydrocarbon (HC), and CO emissions, as well as the fuel consumption. Subsequently, an experimental parametric study was performed using the piston geometry found by the numerical optimization.

A study was performed in the spring of 2001 to chemically characterize exhaust emissions from trucks and buses fueled by various test fuels and operated with and without diesel particle filters. This study was part of a multi-year technology validation program designed to evaluate the emissions impact of ultra-low sulfur diesel fuels and passive diesel particle filters (DPF) in several different heavy-duty vehicle fleets operating in Southern California. The overall study of exhaust chemical composition included organic compounds, inorganic ions, individual elements, and particulate matter in various size-cuts. Detailed descriptions of the overall technology validation program and chemical speciation methodology have been provided in previous SAE publications (2002-01-0432 and 2002-01-0433).