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A 2-D computational model was developed to describe the flow and filtration processes, in a honeycomb structured ceramic diesel particulate trap. This model describes the steady state trap loading, as well as the transient behavior of the flow and filtration processes. The theoretical model includes the effect of a copper fuel additive on trap loading and transient operation. The convective terms were based on a 2-D analytical flow field solution derived from the conservation of mass and momentum equations. The filtration theory incorporated in the time dependent numerical code included the diffusion, inertia, and direct interception mechanisms. Based on a measured upstream particle size distribution, using the filtration theory, the downstream particle size distribution was calculated. The theoretical filtration efficiency, based on particle size distribution, agreed very well (within 1%) with experimental data for a number of different cases.

A 2-D CFD model was developed to describe the heat transfer, and reaction kinetics in a honeycomb structured ceramic diesel particulate trap. This model describes the steady state as well as the transient behavior of the flow and heat transfer during the trap regeneration processes. The trap temperature profile was determined by numerically solving the 2-D unsteady energy equation including the convective, heat conduction and viscous dissipation terms. The convective terms were based on a 2-D analytical flow field solution derived from the conservation of mass and momentum equations (Opris, 1997). The reaction kinetics were described using a discretized first order Arrhenius function. The 2-D term describing the reaction kinetics and particulate matter conservation of mass was added to the energy equation as a source term in order to represent the particulate matter oxidation. The filtration model describes the particulate matter accumulation in the trap.

Experimental Brake Specific Fuel Consumption (BSFC) data are presented for two engines as a function of engine speed, load, outlet coolant temperature and inlet oil temperature. The engines used in the study were the Cummins VT-903 (turbocharged) and the Caterpillar 3208, both being direct-injection and four-cycle. The data were taken for the Cat 3208 engine using a fractional factorial statistical method which reduced the total test matrix from 256 to 64 data points. The experimental data are used in the development of BSFC regression equations as a function of load, speed, outlet coolant temperature and inlet oil temperatures. A mathematical parameter for expressing quantitatively the change of BSFC per 10°F change in coolant and oil temperature is presented. It was found that an increase in the coolant and/or oil temperatures had the effect of reducing BSFC in both engines.

Diesel engine fuel consumption is mainly a function of engine component design and power requirements. However, fuel consumption can also be affected by the environment in which the engine operates. This paper considers two controlling parameters of the engine's thermal environment, oil temperature and coolant temperature. The effects of oil and coolant temperatures on Brake Specific Fuel Consumption (BSFC) are established for a turbocharged diesel engine. Data are also presented for a direct injection, naturally aspirated diesel engine. A matrix of test conditions was run on a Cummins VT-903 diesel engine to evaluate the effects of oil and coolant temperatures on BSFC for several loads and speeds. Loads and speeds were selected based on where a typical semi-tractor engine would operate over the road on a hills and curves route. Oil temperature was monitored and controlled between the oil cooler and the engine. Coolant temperature was monitored and controlled at the engine outlet.

The purpose of this research was to study the pressure drop profiles and regeneration temperature characteristics of Silicon Carbide (SiC) filters with and without a copper-based additive in the fuel, and also to compare their performance with two cordierite traps designated as EX-47 and EX-80. The collection of the particulate matter inside the trap imposes a backpressure on the engine which requires a periodic oxidation or regeneration of the particulate matter. The presence of copper additive in the fuel reduces the particulate ignition temperature from approximately 500 to 375°C. Two SiC systems were tested during this research. The first system consisted of one 14 L SiC trap, while the second system, the dual trap system (DTS), consisted of two 12 L SiC traps mounted in parallel. The test matrix included two types of regeneration tests, controlled and uncontrolled and three levels of Cu fuel additive (0, 30, and 60 ppm).

The goals of this research are to understand the regeneration process in ceramic (Cordierite) monolith traps using a copper fuel additive and to investigate the various conditions that lead to trap regeneration failure. The copper additive lowers the trap regeneration temperature from approximately 500 °C to 375 °C and decreases the time necessary for regeneration. Because of these characteristics, it is important to understand the effect of the additive on regeneration when excessive particulate matter accumulation occurs in the trap. The effects of particulate mass loading on regeneration temperatures and regeneration time were studied for both the controlled (engine operated at full load rated speed) and uncontrolled (trap regeneration initiated at full load rated speed after which the engine was cut to idle) conditions. The trap peak temperatures were higher for the uncontrolled than the controlled regeneration.

To meet future NO, heavy-duty diesel emissions standards, exhaust gas recirculation (EGR) technology is likely to be used. To improve fuel economy and further lower emissions, the recirculated exhaust gas needs to be cooled, with the possibility that cooling of the exhaust gas may form sulfuric acid condensate in the EGR cooler. This corrosive condensate can cause EGR cooler failure and consequentially result in severe damage to the engine. Both a literature review and a preliminary experimental study were conducted. In this study, a manually controlled EGR system was installed on a 1995 Cummins Ml l-330E engine which was operated at EPA mode 9* (1800 rpm and 75% load). The Goksoyr-Ross method (1)** was used to measure the particle-phase sulfate and vapor-phase H2SO4 and SO2 at the inlet and outlet locations of the EGR cooler, obtaining H2SO4 and SO2 concentrations. About 0.5% of fuel sulfur in the EGR cooler was in the particle-phase.

The purpose of this study was to investigate the pressure drop and regeneration characteristics of a silicon carbide (SiC) wall-flow diesel particulate filter. The performance of a 25 μm mean pore size SiC dual trap system (DTS) consisting of two 12 liter traps connected in parallel in conjunction with a copper (Cu) fuel additive was evaluated. A comparison between the 25 μm DTS and a 15 μm DTS was performed, in order to show the effect of trap material mean pore size on trap loading and regeneration behavior. A 1988 Cummins LTA 10-300 diesel engine was used to evaluate the performance of the 15 and 25 μm DTS. A mathematical model was developed to better understand the thermal and catalytic oxidation of the particulate matter. For all the trap steady-state loading tests, the engine was run at EPA mode 11 for 10 hours. Raw exhaust samples were taken upstream and downstream of the trap system in order to determine the DTS filtration efficiency.

Turbocharging, in addition to increasing an engine's power output, can be effectively used to maintain exhaust emission levels while improving fuel economy. This paper presents the emission and performance results obtained from a turbocharged multicylinder spark ignition engine with thermal reactors and exhaust gas recirculation (EGR) operated at steady-state, part-load conditions for four engine speeds. When comparing a turbocharged engine to a larger displacement naturally aspirated engine of equal power output, the emissions expressed in grams per mile were relatively unchanged both with and without EGR. However, turbocharging provided an average of 20% improvement in fuel economy both with and without EGR. When comparing the turbocharged and nonturbocharged versions of the same engine without EGR at a given load and speed, turbocharging increased the hydrocarbon (HC) and carbon monoxide (CO) emissions and decreased oxides of nitrogen (NOx) emissions.

This paper presents the development of a computer model to simulate fuel usage and emission contributions of the past and future truck and bus population in the United States. The projected future years are beyond 1976 to 1990. The trends in vehicle population growth, yearly miles traveled and ton-miles are also calculated by the model. The model developed is flexible and brings together several technical concepts which reflect recent inputs from industry and government. The formulation of the model is based on a systems approach, in which the several submodels (the "Population," "Mileage," "Fuel Usage," and "Emission") are interrelated. The preliminary quantitative results are discussed to demonstrate the satisfactory performance of the computer model. Increased rates of dieselization are analyzed to determine their effect on reducing fuel consumption and the impact on total emission contributions. The use of the computer model to study an urban area for air quality is discussed.

Active regeneration experiments were carried out on a production 2007 Cummins 8.9L ISL engine and associated diesel oxidation catalyst (DOC) and catalyzed particulate filter (CPF) aftertreatment system. The effects of SME biodiesel blends were investigated to determine the particulate matter (PM) oxidation reaction rates for active regeneration. The experimental data from this study will also be used to calibrate the MTU-1D CPF model [1]. The experiments covered a range of CPF inlet temperatures using ULSD, B10, and B20 blends of biodiesel. The majority of the tests were performed at a CPF PM loading of 2.2 g/L with in-cylinder dosing, although 4.1 g/L and a post-turbo dosing injector were also investigated. The PM reaction rate was shown to increase with increasing percent biodiesel in the test fuel as well as increasing CPF temperature.

Passive regeneration (oxidation of particulate matter without using an external energy source) of particulate filters in combination with active regeneration is necessary for low load engine operating conditions. For low load conditions, the exhaust gas temperatures are less than 250°C and the PM oxidation rate due to passive regeneration is less than the PM accumulation rate. The objective of this research was to experimentally investigate active regeneration of a catalyzed particulate filter (CPF) using diesel fuel injection in the exhaust gas after the turbocharger and before a diesel oxidation catalyst (DOC) and to collect data for extending the MTU 1-D 2-layer model to include the simulation of active regeneration. The engine used in this study was a 2002 Cummins ISM turbo charged 10.8 L heavy duty diesel engine with cooled EGR. The exhaust after-treatment system consisted of a Johnson Matthey DOC and CPF (a CCRT®).

A model for calculating the trap pressure drop, particulate mass inside the trap and various particulate and trap properties was developed using the steady-state data and the theory developed by Konstandopoulos & Johnson, 1989. Changes were made with respect to the calculation of clean pressure drop, particulate layer porosity and the particulate layer permeability. This model was validated with the data obtained from the steady-state data run with different traps supplied by Corning Inc. The data were collected using the 1988 Cummins L-10 heavy-duty diesel engine using No.2 low sulfur diesel fuel. The three different traps were EX 80 (100 cell density), EX 80 (200 cell density) and EX 66 (100 cell density) all with a 229 mm diameter and 305 mm length. These traps were subjected to different particulate matter loadings at different speeds. The traps were not catalyzed.

A 2007 Cummins ISL 8.9L direct-injection common rail diesel engine rated at 272 kW (365 hp) was used to load the filter to 2.2 g/L and passively oxidize particulate matter (PM) within a 2007 OEM aftertreatment system consisting of a diesel oxidation catalyst (DOC) and catalyzed particulate filter (CPF). Having a better understanding of the passive NO₂ oxidation kinetics of PM within the CPF allows for reducing the frequency of active regenerations (hydrocarbon injection) and the associated fuel penalties. Being able to model the passive oxidation of accumulated PM in the CPF is critical to creating accurate state estimation strategies. The MTU 1-D CPF model will be used to simulate data collected from this study to examine differences in the PM oxidation kinetics when soy methyl ester (SME) biodiesel is used as the source of fuel for the engine.

The effect of the use of a manganese-copper fuel additive with a Corning EX-47 particulate trap on heavy-duty diesel emissions has been investigated; reductions in total particulate matter (70%), sulfates (65%), and the soluble organic fraction (SOF) (62%) were measured in the diluted (15:1) exhaust and solids were reduced by 94% as measured in the raw exhaust. The use of the additive plus the trap had the same effect on gaseous emissions (hydrocarbons and oxides of nitrogen) as did the trap alone. The use of the additive without the trap had no effect on measured gaseous emissions, although sulfate increased by 20%. Approximately 50% of the metals added to the fuel were calculated to be retained in the engine system. The metals emitted by the engine were collected very efficiently (>97%) by the trap even during regeneration, which occured 180°C lower when the additive was used.

The development of the DDC methanol engine has been an evolutionary process, with each subsequent configuration showing significant durability and/or emission improvement over its predecessor. Sixty demonstration engines are now in service in the field, including fifty-four (54) urban bus engines, five (5) truck engines, and one (1) generator set engine. While nitrogen oxide (NOx) and particulate emissions from the methanol engine are inherently low, a durable solution to the effective control of hydrocarbon (HC) emissions has been an especially challenging area. The 1991 Federal urban bus transient emission standards (including 0.10 gm/bhp-hr particulate) have been met with several combinations of compression ratio, intake port height, exhaust valve cam profile, injector tip design, and electronic control strategies, and without exhaust aftertreatment devices or fuel ignition improvers.

A quasi-steady 1-dimensional computer model of a catalyzed particulate filter (CPF) capable of simulating active regeneration of the CPF via diesel fuel injection upstream of a diesel oxidation catalyst (DOC) or other means to increase the exhaust gas temperature has been developed. This model is capable of predicting gaseous species concentrations (HC's, CO, NO and NO2) and exhaust gas temperatures within and after the CPF, for given input values of gaseous species and PM concentrations before the CPF and other inlet variables such as time-varying temperature of the exhaust gas at the inlet of the CPF and volumetric flow rate of exhaust gas.

Active regeneration experiments were performed on a production diesel aftertreatment system containing a diesel oxidation catalyst and catalyzed particulate filter (CPF) using blends of soy-based biodiesel. The effects of biodiesel on particulate matter oxidation rates in the filter were explored. These experiments are a continuation of the work performed by Chilumukuru et al., in SAE Technical Paper No. 2009-01-1474, which studied the active regeneration characteristics of the same aftertreatment system using ultra-low sulfur diesel fuel. Experiments were conducted using a 10.8 L 2002 Cummins ISM heavy-duty diesel engine. Particulate matter loading of the filter was performed at the rated engine speed of 2100 rpm and 20% of the full engine load of 1120 Nm. At this engine speed and load the passive oxidation rate is low. The 17 L CPF was loaded to a particulate matter level of 2.2 g/L.

This research quantifies the effects of a copper fuel additive on the regulated [oxides of nitrogen (NOx), hydrocarbons (HC) and total particulate matter (TPM)] and unregulated emissions [soluble organic fraction (SOF), vapor phase organics (XOC), polynuclear aromatic hydrocarbons (PAH), nitro-PAH, particle size distributions and mutagenic activity] from a 1988 Cummins LTA10 diesel engine using a low sulfur fuel. The engine was operated at two steady state modes (EPA modes 9 and 11, which are 75 and 25% load at rated speed, respectively) and five additive levels (0, 15, 30, 60 and 100 ppm Cu by mass) with and without a ceramic trap. Measurements of PAH and mutagenic activity were limited to the 0, 30 and 60 ppm Cu levels. Data were also collected to assess the effect of the additive on regeneration temperature and duration. Copper species collected within the trap were identified and exhaust copper concentrations quantified.

This paper presents an approach to modeling the United States truck and bus population. A detailed model is developed that utilizes domestic factory sales figures combined with a scrappage factor as a building block for the total population. Comparison with historical data for 1958-1970 shows that the model follows trends well for intermediate parameters such as total vehicle miles per year, total fuel consumption, scrappage, etc. Fuel consumption and HC, CO, NO2, CO2 and particulate matter emissions for gasoline and diesel engines are of primary interest. The model details these parameters for the time span 1958-2000 in one-year increments. For HC and CO, truck and bus emissions could equal or exceed automobile emissions in the early 1980s, depending on the degree of control. Three population control strategies are analyzed to determine their effects on reducing fuel consumption or air pollution in later years.