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Light duty vehicle emission standards are getting more stringent than ever before as stipulated by US EPA Tier 2 Standards and LEV III regulations proposed by CARB. The research in this paper sponsored by US DoE is focused towards developing a Tier 2 Bin 2 Emissions compliant light duty pickup truck with class leading fuel economy targets of 22.4 mpg “City” / 34.3 mpg “Highway”. Many advanced technologies comprising both engine and after-treatment systems are essential towards accomplishing this goal. The objective of this paper would be to discuss key engine technology enablers that will help in achieving the target emission levels and fuel economy. Several enabling technologies comprising air-handling, fuel system and base engine design requirements will be discussed in this paper highlighting both experimental and analytical evaluations.

In order to meet common fuel specifications such as cetane number and volatility, a refinery must blend a number of refinery stocks derived from various process units in the refinery. Fuel chemistry can be significantly altered in meeting fuel specifications. Additionally, fuel specifications are seldom changed in isolation, and the drive to meet one specification may alter other specifications. Homogeneous charge compression ignition (HCCI) engines depend on the kinetic behavior of a fuel to achieve reliable ignition and are expected to be more dependent on fuel specifications and chemistry than today's conventional engines. Regression analysis can help in determining the underlying relationships between fuel specifications, chemistry, and engine performance. Principal Component Analysis (PCA) is used as an adjunct to regression analysis in this work, because of its ability to deal with co-linear variables and potential to uncover ‘hidden’ relationships between the variables.

The influence of various diesel fuel properties on the steady state emissions and performance of a Cummins light-duty (ISB) engine modified for single cylinder operation has been studied at the mid-load “cruise” operating condition. Designed experiments involving independent manipulation of both fuel properties and engine control parameters have been used to build statistical engine response models. The models were then applied to optimize for the minimum fuel consumption subject to specific constraints on emissions and mechanical limits and also to estimate the optimum engine control parameter settings and fuel properties. The study reveals that under the high EGR, diffusion-burn dominated conditions encountered during the experiments, NOx is impacted by cetane number and the distillation characteristics. Lower T50 (mid-distillation temperature) resulted in simultaneous reductions in both NOx and smoke, and higher cetane number provided an additional small NOx benefit.

With increasing energy prices and concerns about the environmental impact of greenhouse gas (GHG) emissions, a growing number of national governments are putting emphasis on improving the energy efficiency of the equipment employed throughout their transportation systems. Within the U.S. transportation sector, energy use in commercial vehicles has been increasing at a faster rate than that of automobiles. A 23% increase in fuel consumption for the U.S. heavy duty truck segment is expected from 2009 to 2020. The heavy duty vehicle oil consumption is projected to grow while light duty vehicle (LDV) fuel consumption will eventually experience a decrease. By 2050, the oil consumption rate by LDVs is anticipated to decrease below 2009 levels due to CAFE standards and biofuel use. In contrast, the heavy duty oil consumption rate is anticipated to double. The increasing trend in oil consumption for heavy trucks is linked to the vitality, security, and growth of the U.S. and global economies.

The performance of an organic Rankine cycle (ORC) that recovers heat from the exhaust of a heavy-duty diesel engine was simulated. The work was an extension of a prior study that simulated the performance of an experimental ORC system developed and tested at Oak Ridge National laboratory (ORNL). The experimental data were used to set model parameters and validate the results of that simulation. For the current study the model was adapted to consider a 15 liter turbocharged engine versus the original 1.9 liter light-duty automotive turbodiesel studied by ORNL. Exhaust flow rate and temperature data for the heavy-duty engine were obtained from Southwest Research Institute (SwRI) for a range of steady-state engine speeds and loads without EGR. Because of the considerably higher exhaust gas flow rates of the heavy-duty engine, relative to the engine tested by ORNL, a different heat exchanger type was considered in order to keep exhaust pressure drop within practical bounds.

In April 2003, a small field study was initiated to evaluate the effect of lube oil formulations on ash accumulation in heavy-duty diesel DPFs. Nine (9) Fuel Delivery Trucks were retrofitted with passive diesel particulate filters and fueled with ultra low sulfur diesel which contains less than 15 ppm sulfur. Each vehicle operated in the field for 18 months or approximately 160,000 miles (241,401 km) using one of three lube oil formulations. Ash accumulation was determined for each vehicle and compared between the three differing lube oil formulations. Ash analyses, used lube oil analysis and filter substrate evaluations were performed to provide a complete picture of DPF operations. The evaluation also examined some of the key parameters that allows for the successful implementation of the passive DPF in this heavy-duty application.

Evaluation of the platooning legislative space suggests a limited near-term opportunity for autonomous vehicles as currently only nine states have platooning and autonomous favorable legislations. An extensive closed-loop vehicle model simulation was conducted to quantify two-truck platooning fuel economy entitlement benefits across all United States (US) interstate routes (I-xx) spanning over 40,000 miles as compared to a single truck. A simultaneous study was carried out to identify the density of Class 8 heavy-duty trucks on these interstates, using the Freight Analysis Framework (FAF) 4 database. These two studies were combined to ascertain interstates that foresee the least fuel consumption due to platooning and thus identifying states with the most platooning benefits. Identification of states with most platooning benefits provides realistic data to push for autonomous driving and platooning legislations.

Piston cooling nozzles/jets play several crucial roles in the power cylinder of an internal combustion engine. Primarily, they help with the thermal management of the piston and provide lubrication to the cylinder liner and the piston’s wrist pin. In order to evaluate the oil jet characteristics from various piston cooling nozzle (PCN) designs, a quantitative and objective process was developed. The PCN characterization began with a computational fluid dynamics (CFD) turbulent model to analyze the mean oil velocity and flow distribution at the nozzle exit/tip. Subsequently, the PCN was tested on a rig for a given oil temperature and pressure. A high-speed camera captured images at 2500 frames per second to observe the evolution of the oil stream as a function of distance from the nozzle exit. An algorithm comprised of standard digital image processing techniques was created to calculate the oil jet width and density.

Accumulation of lubricant and fuel derived ash in the diesel particulate filter (DPF) during vehicle operation results in a significant increase of pressure drop across the after-treatment system leading to loss of fuel economy and reduced soot storage capacity over time. Under certain operating conditions, the accumulated ash and/or soot cake layer can collapse resulting in ash deposits upstream from the typical ash plug section, henceforth termed mid-channel ash deposits. In addition, ash particles can bond (either physically or chemically) with neighboring particles resulting in formation of bridges across the channels that effectively block access to the remainder of the channel for the incoming exhaust gas stream. This phenomenon creates serious long-term durability issues for the DPF, which often must be replaced. Mid-channel deposits and ash bridges are extremely difficult to remove from the channels as they often sinter to the substrate.

As the world market develops for biodiesel fuels, it is likely that a wider variety of biodiesels will become available, both locally and globally, and require engines to operate on a wider variety of fuels than experienced today. At the same time, tighter emissions regulations and a drive for improved fuel economy have focused interest on advanced combustion modes such as HCCI or PCCI, which are known to be more sensitive to fuel properties. This research covers two series of biodiesel fuels. In the first, B20 blends of natural methyl esters derived from palm, coconut, rape, soy, and mustard were evaluated at light load in an HCCI research engine to determine combustion and performance characteristics. These fuels showed performance differences between the biodiesels and the base #2 ULSD fuel, but did not allow separation of chemical effects due to the small number of fuels and correlation of various properties.

Wheel loader subsystems are multi-domain in nature, including controls, mechanisms, hydraulics, and thermal. This paper describes the process of developing a multi-domain simulation of a wheel loader. Working hydraulics, kinematics of the working tool, driveline, engine, and cooling system are modeled in LMS Imagine.Lab Amesim. Contacts between boom/bucket and bucket/ground are defined to constrain the movement of the bucket and boom. The wheel loader has four heat exchangers: charge air cooler, radiator, transmission oil cooler, and hydraulic oil cooler. Heat rejection from engine, energy losses from driveline, and hydraulic subsystem are inputs to the heat exchangers. 3D CFD modeling was done to calibrate airflows through heat exchangers in LMS Amesim. CFD modeling was done in ANSYS FLUENT® using a standard k - ε model with detailed fan and underhood geometry.

Fuel usage negatively impacts the environment and is a significant portion of operational costs of moving freight globally. Reducing fuel consumption is key to lessening environmental impacts and maximizing freight efficiency, thereby increasing the profit margin of logistic operators. In this paper, fuel economy improvements of a cab-over style 49T heavy duty Foton truck powered by a Cummins 12-liter engine are studied and systematically applied for the China market. Most fuel efficiency improvements are found within the vehicle design when compared to opportunities available at the engine level. Vehicle design (improved aerodynamics), component selection/matching (low rolling resistance tires), and powertrain electronic features integration (shift schedule/electronic trim) offer the largest opportunities for lowering fuel consumption.

The paper will discuss the design and development of heavy-duty diesel engines to meet the US EPA 2010 on-highway standards - 0.2 g/HP-hr NOx and 0.01 g/HP-hr particulate matter (PM). In meeting these standards a combination of in-cylinder control and aftertreatment control for both NOx and particulate has been used. For NOx control, a combination of cooled exhaust gas recirculation (EGR) and selective catalytic reduction (SCR) is used. The SCR catalyst uses copper zeolite to achieve high levels of NOx conversion efficiency with minimal ammonia slip and unparalleled thermal durability. For particulate control, a diesel particulate filter (DPF) with upstream oxidation catalyst (DOC) is used. While the DPF may be actively regenerated when required, it operates predominantly with passive regeneration - enabled by the high NOx levels between the engine and the DPF, associated with high efficiency SCR systems and NO₂ production across the DOC.

This study analyzed the impact of transient and multi-mode engine conditions on emissions of dioxins and furans from a variety of diesel aftertreatment configurations. Exhaust aftertreatment systems included combinations of diesel oxidation catalyst, diesel particulate filter, and either Cu/zeolite or Fe/zeolite selective catalytic reduction catalyst. EPA method TO-9A was modified for proportional exhaust gas sampling, whereas EPA method 0023A was modified for raw exhaust gas sampling. Dioxin and furan emissions were first measured with modified method TO-9A during Federal Test Procedure transient cycles, but no toxic dioxins or furans were detected. Measurements were then taken with modified method 0023A during Ramped Mode Cycles-Supplemental Emissions Test experiments. Because more rigorous pre-cleaning and sample extraction procedures were used with this method and lower detection limits were achieved by the analytical laboratory, some dioxin and furan congeners were detected.

A multi-year technology validation program was completed in 2001 to evaluate ultra-low sulfur diesel fuels and passive diesel particle filters (DPF) in several different diesel fleets operating in Southern California. The fuels used throughout the validation program were diesel fuels with less than 15-ppm sulfur content. Trucks and buses were retrofitted with two types of passive DPFs. Two rounds of emissions testing were performed to determine if there was any degradation in the emissions reduction. The results demonstrated robust emissions performance for each of the DPF technologies over a one-year period. Detailed descriptions of the overall program and results have been described in previous SAE publications [2, 3, 4, 5]. In 2002, a third round of emission testing was performed by NREL on a small subset of vehicles in the Ralphs Grocery Truck fleet that demonstrated continued robust emissions performance after two years of operation and over 220,000 miles.

The present study examines the impact of using low thermal mass (LTM) turbine housing designs on the transient characteristics of the turbine outlet temperature for a light-duty diesel standard certification cycle (FTP75). For a controlled exhaust flow, the turbine outlet temperature will directly determine the impact on an aftertreatment system warm-up from a cold state, typical of engine-off and engine idling conditions. The performance of the aftertreatment system such as a Selective Catalytic Reduction (SCR) system is highly dependent on how quickly it warms up to its desirable temperature to be able to convert the harmful oxides of Nitrogen (NOx) to gaseous Nitrogen. Previous works have focused on mostly insulating the exhaust manifold and turbine housing to conserve the heat going into the aftertreatment system. The use of LTM turbine housing has not been previously considered as a means for addressing this requirement.

This paper presents an extension of our earlier work on Cummins Vehicle Mission Simulation (VMS) software. Previously, we presented VMS as a Windows based analysis tool to simulate vehicle missions quickly and to gauge, communicate, and improve the value proposition of Cummins engines to customers. We have subsequently extended this VMS architecture to build a grid-computing platform to support high volume of simulation needs. The building block of the grid-computing version of VMS is an executable file that consists of vehicle and engine simulation models compiled using Real Time Workshop. This executable file integrates MATLAB and Simulink with Java, XML, and JDBC technologies and interacts with the MySQL database. Our grid consists of a cluster of twenty Linux servers with quad-core processors. The Sun Grid Engine software suite that administers this cluster can batch-queue and execute 80 simulations concurrently.

Several complementary experimental techniques were applied to investigate kinetics of diesel soot oxidation by O2 in an attempt to provide accurate data for modeling of the Diesel Particulate Filters regeneration process. For two diesel soot samples with measurably different properties, it was shown that the complexity of their overall kinetic behavior was due to an initial period of rapidly changing reactivity. This initial high reactivity was understood not to be related to the SOF, and was quantitatively correlated to the extent of soot pre-oxidation. This initial reactivity can affect the averaged apparent kinetic parameters, for example resulting in the lower apparent activation energy values. After the initial soot pre-oxidation, which consumed ∼10-25% of carbon, the remaining soot was behaving very uniformly, producing linear Arrhenius plots in a remarkably broad range of temperatures (330-610°C) and integral conversions (up to 90%).

Particulate emission control from diesel engines is one of the major concerns in the urban areas in California. Recently, regulations have been proposed for stringent PM emission requirements from both existing and new diesel engines. As a result, particulate emission control from urban diesel engines using advanced particulate filter technology is being evaluated at several locations in California. Although ceramic based particle filters are well known for high PM reductions, the lack of effective and durable regeneration system has limited their applications. The continuously regenerated diesel particulate filter (CRDPF) technology discussed in this presentation, solves this problem by catalytically oxidizing NO present in the diesel exhaust to NO2 which is utilized to continuously combust the engine soot under the typical diesel engine operating condition.

Regeneration of diesel particulate filters poses major challenges in developing the particulate matter emission control technology to meet EPA 2007/2010 emissions regulations. The problem areas are multifold due to the complexity involved in designing the filter system, developing regeneration strategies and controlling the regeneration process. This paper discusses the need for active regeneration systems. It also addresses several key limitations and trade-offs between the regeneration strategy, chemical kinetics, exhaust gas temperature and the regeneration efficiency. Passive regeneration of diesel particulate filter systems is known to be highly dependent on the engine-out [NOx/PM] ratio as well as exhaust temperature over the duty cycle. Using catalytic oxidation of auxiliary fuel injected into the system, the exhaust gas temperature can be successfully enhanced for filter regeneration.