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Technical Paper

Spatial Non-Uniformities in Diesel Particulate Trap Regeneration

2001-03-05
2001-01-0908
Diesel particulate trap regeneration is a complex process involving the interaction of phenomena at several scales. A hierarchy of models for the relevant physicochemical processes at the different scales of the problem (porous wall, filter channel, entire trap) is employed to obtain a rigorous description of the process in a multidimensional context. The final model structure is validated against experiments, resulting in a powerful tool for the computer-aided study of the regeneration behavior. In the present work we employ this tool to address the effect of various spatial non-uniformities on the regeneration characteristics of diesel particulate traps. Non-uniformities may include radial variations of flow, temperature and particulate concentration at the filter inlet, as well as variations of particulate loading. In addition, we study the influence of the distribution of catalytic activity along the filter wall.
Technical Paper

Validation of a Model and Development of a Simulator for Predicting the Pressure Drop of Diesel Particulate Filters

2001-03-05
2001-01-0911
As demand for wall-flow Diesel Particulate Filters (DPF) increases, accurate predictions of DPF behavior, and in particular their pressure drop, under a wide range of operating conditions bears significant engineering applications. In this work, validation of a model and development of a simulator for predicting the pressure drop of clean and particulate-loaded DPFs are presented. The model, based on a previously developed theory, has been validated extensively in this work. The validation range includes utilizing a large matrix of wall-flow filters varying in their size, cell density and wall thickness, each positioned downstream of light or heavy duty Diesel engines; it also covers a wide range of engine operating conditions such as engine load, flow rate, flow temperature and filter soot loading conditions. The validated model was then incorporated into a DPF pressure drop simulator.
Technical Paper

A Study of the Effect of a Catalyzed Particulate Filter on the Emissions from a Heavy-Duty Diesel Engine with EGR

2001-03-05
2001-01-0910
The effects of a catalyzed particulate filter (CPF) and Exhaust Gas Recirculation (EGR) on heavy-duty diesel engine emissions were studied in this research. EGR is used to reduce the NOx emissions but at the same time it can increase total particulate matter (TPM) emissions. CPF is technology available for retrofitting existing vehicles in the field to reduce the TPM emissions. A conventional low sulfur fuel (371 ppm S) was used in all the engine runs. Steady-state loading and regeneration experiments were performed with CPF I to determine its performance with respect to pressure drop and particulate mass characteristics at different engine operating conditions. From the dilution tunnel emission characterization results for CPF II, at Mode 11 condition (25% load - 311 Nm, 1800 rpm), the TPM, HC and vapor phase emissions (XOC) were decreased by 70%, 62% and 62% respectively downstream of the CPF II.
Technical Paper

Inertial Contributions to the Pressure Drop of Diesel Particulate Filters

2001-03-05
2001-01-0909
Wall-flow Diesel particulate filters operating at low filtration velocities usually exhibit a linear dependence between the filter pressure drop and the flow rate, conveniently described by a generalized Darcy's law. It is advantageous to minimize filter pressure drop by sizing filters to operate within this linear range. However in practice, since there often exist serious constraints on the available vehicle underfloor space, a vehicle manufacturer is forced to choose an “undersized” filter resulting in high filtration velocities through the filter walls. Since secondary inertial contributions to the pressure drop become significant, Darcy's law can no longer accurately describe the filter pressure drop. In this paper, a systematic investigation of these secondary inertial flow effects is presented.
Technical Paper

A Computer Simulation of the Turbocharged Diesel Engine as an Enhancement of the Vehicle Engine Cooling System Simulation

1997-05-19
971804
A computer simulation of the turbocharged direct- injection diesel engine was developed to enhance the capabilities of the Vehicle Engine Cooling System Simulation (VECSS) developed at Michigan Technological University. The engine model was extensively validated against Detroit Diesel Corporation's (DDC) Series 60 engine data. In addition to the new engine model a charge-air-cooler model was developed and incorporated into the VECSS. A Freightliner truck with a Detroit Diesel's Series 60 engine, Behr McCord radiator, AlliedSignal/Garrett Automotive charge air cooler, Kysor DST variable speed fan clutch and other cooling system components was used for the study. The data were collected using the Detroit Diesel Electronic Controls (DDEC)-Electronic Control Module (ECM) and Hewlett Packard data acquisition system. The enhanced model's results were compared to the steady state TTD (top tank differential) data.
Technical Paper

A Study of the Effects of Exhaust Gas Recirculation on Heavy-Duty Diesel Engine Emissions

1998-05-04
981422
The effects of exhaust gas recirculation (EGR) on heavy-duty diesel emissions were studied at two EPA steady-state operating conditions, old EPA mode 9* (1800 RPM, 75% Load) and old EPA mode 11 (1800 RPM, 25% Load). Data were collected at the baseline, 10% and 16% EGR rates for both EPA modes. The study was conducted using a 1995 Cummins M11-330E heavy-duty diesel engine and compared to the baseline emissions from the Cummins 1988 and 1991 L10 engines. The baseline gas-, vapor- and particle-phase emissions were measured together with the particle size distributions at all modes of operation. The total particulate matter (TPM) and vapor phase (XOC) samples were analyzed for physical, chemical and biological properties. The results showed that newer engines with electronic engine controls and higher injector pressures produce TPM decreases from the 1988 to 1991 to 1995 engines with the solids decreasing more than the soluble organic fraction (SOF) of TPM.
Technical Paper

Fuel Film Dynamics in the Intake Port of a Fuel Injected Engine

1994-03-01
940446
Up to 80 percent of the total hydrocarbons emitted during the EPA Federal emissions test are produced in the first five minutes of this procedure. It has been theorized that this is in part due to wall wetting of the intake port and cylinder. This study measures the behavior of the fuel film thickness in the intake port during cold starting, steady state and transient operation. Three injector spray patterns with varying droplet sizes were utilized for the tests. The fuel film thickness in the intake port of a Ford 1.9L engine was measured using optical sensors. It was found that the spray pattern and droplet size affected the port wall wetting characteristics.
Technical Paper

Exhaust Flow Separation in a Two Stroke Engine

1996-02-01
960744
The two stroke direct injected gasoline engine is in part characterized by low temperature exhaust flow, particularly at light loads, due to the fresh air scavenging of the combustion chamber during the exhaust process. This study investigated the possibility of separating the exhaust flow into two regimes: 1) high temperature flow of the combustion products, and 2) low temperature flow from the fresh air scavenging process. Separation of the exhaust flow was accomplished by a mechanical device placed in the exhaust stream. In this way, emissions from the exhaust could be handled by two different catalysts and/or processes, each optimized for different temperature ranges and flow compositions. The first portion of this study involved validation of a computer model, using experimental data from a single cylinder engine with a stationary exhaust port and splitter.
Technical Paper

High Performance Auto Parts Could be Produced Using CastCon Manufacturing Process

1997-02-24
970429
High performance auto parts such as aluminum composite cladding aluminum brake and Ti/Ti3/Al joined exhaust valve with localized Ti+TiC composite coating could be produced using a new manufacturing method - the CastCon process. The aluminum composite cladding aluminum brake consists of an aluminum alloy body with a cladding of SiC and graphite particulate filled aluminum composite on the friction surface of a brake disk or a drum. This structure can ensure an over-all light weight and integral strength and ductility. The SiC particulate in the cladding composite increases abrasion resistance and the graphite particulate provides required lubrication. The cladding can be as thick as desired. There is a flexibility in the manufacturing process for selecting SiC and graphite loading volumes as well as particulate size and shape. This allows the part to be engineered to achieve maximum performance.
Technical Paper

A Study of the Regeneration Process in Diesel Particulate Traps Using a Copper Fuel Additive

1996-02-01
960136
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.
Technical Paper

The Effect of Fuel and Engine Design on Diesel Exhaust Particle Size Distributions

1996-02-01
960131
The objective of this research was to obtain diesel particle size distributions from a 1988 and a 1991 diesel engine using three different fuels and two exhaust control technologies (a ceramic particle trap and an oxidation catalytic converter). The particle size distributions from both engines were used to develop models to estimate the composition of the individual size particles. Nucleation theory of the H2O and H2SO4 vapor is used to predict when nuclei-mode particles will form in the dilution tunnel. Combining the theory with the experimental data, the conditions necessary in the dilution tunnel for particle formation are predicted. The paper also contains a discussion on the differences between the 1988 and 1991 engine's particle size distributions. The results indicated that nuclei mode particles (0.0075-0.046 μm) are formed in the dilution tunnel and consist of more than 80% H2O-H2SO4 particles when using the 1988 engine and 0.29 wt% sulfur fuel.
Technical Paper

An Automated Patternator for Fuel Injector Sprays

1996-02-01
960108
The spray pattern of a fuel injector is a key factor in the mixing of the fuel with the air. One effective means of determining the fuel distribution in the spray is to collect the fuel in tubes, from various regions of the spray. The amount of fuel in the tubes is measured. These measurements are used to create diagrams and curves which graphically represent the fuel distribution within the spray. The term “Patternator” has come to mean a device which determines the spray distribution, in the sense that the device determines the pattern of the spray. The objective of this paper is to describe the operation, features, and performance of an automated patternator designed and built at Michigan Technological University for Ford Motor Company. The patternator system was constructed for rapid determination of the spray pattern in order to expedite the development of automotive port fuel injectors.
Technical Paper

The Use of Results from Computational Fluid Dynamic Fuel Injector Modeling to Predict Spray Characteristics

1996-05-01
961191
The fluid flow characteristics inside compound silicon micro machined port fuel injector nozzles were analyzed through the use of computational fluid dynamics (CFD). This study was undertaken in order to gain a better understanding of the fluid mechanics taking place in the compound orifice plate. In addition, the calculated computational results will be used to predict the fuel spray patterns and sauter mean diameters of the sprays. The influence of orifice plate geometry on calculated turbulent kinetic energies and fuel spray patterns was also studied and will be discussed. The results of this investigation indicate that the fluid flow characteristics inside the compound silicon micro machined port fuel injector nozzle are influenced by the geometries of the compound orifice plate, and that the flow characteristic inside the orifice plate effect the type of spray produced by the injector.
Technical Paper

Effects of an Oxidation Catalytic Converter on Regulated and Unregulated Diesel Emissions

1994-03-01
940243
In this study, the effects of an oxidation catalytic converter (OCC) on regulated and unregulated emissions from a 1991 prototype Cummins I.10-310 diesel engine fueled with a 0.01 weight percent sulfur fuel were investigated. The OCC's effects were determined by measuring and comparing selected raw exhaust emissions with and without the platinum-based OCC installed in the exhaust system, with the engine operated at three steady-state modes. It was found that the OCC had no significant effect on oxides of nitrogen (NOX) and nitric oxide (NO) at any mode, but reduced hydrocarbon (HC) emmissions by 60 to 70 percent. The OCC reduced total particulate matter (TPM) levels by 27 to 54 percent, primarily resulting from 53 to 71 percent reductions of the soluble organic fraction (SOF). The OCC increased sulfate (SO42-) levels at two of the three modes (modes 9 and 10), but the overall SO42- contribution to TPM was less than 6 percent at all modes due to the low sulfur level of the fuel.
Technical Paper

A Review of Diesel Particulate Control Technology and Emissions Effects - 1992 Horning Memorial Award Lecture

1994-03-01
940233
Studies have been conducted at Michigan Technological University (MTU) for over twenty years on methods for characterizing and controlling particulate emissions from heavy-duty diesel engines and the resulting effects on regulated and unregulated emissions. During that time, control technologies have developed in response to more stringent EPA standards for diesel emissions. This paper is a review of: 1) modern emission control technologies, 2) emissions sampling and chemical, physical and biological characterization methods and 3) summary results from recent studies conducted at MTU on heavy-duty diesel engines with a trap and an oxidation catalytic converter (OCC) operated on three different fuels. Control technology developments discussed are particulate traps, catalysts, advances in engine design, the application of exhaust gas recirculation (EGR), and modifications of fuel formulations.
Technical Paper

Modeling of Early Pressure Rise and Flame Growth in a Spark Ignition Engine

1994-10-01
941930
A thermodynamical model of the ignition and flame growth process was developed to understand and minimize cycle-to-cycle variations in pressure due to minor differences in flame kernel growth at the spark plug electrode between cycles. Initial flame kernel size after the spark breakdown process was determined by solving the one-dimensional cylindrical shock flow equation. Overall reaction rates, flame speeds including turbulence and intensity, high temperature equilibrium and other thermodynamic properties were calculated by peripheral sub-models. Relative effects of spark power, heat loss to the spark plug, and the chemical heat release were studied under varying engine conditions. Results show that breakdown energy has a significant effect on the formation and size of the initial kernel and that the effect of flame kernel velocity on subsequent combustion was considerable at specific engine conditions.
Technical Paper

Effects of a Ceramic Particle Trap and Copper Fuel Additive on Heavy-Duty Diesel Emissions

1994-10-01
942068
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.
Technical Paper

A Study of the Regeneration Characteristics of Silicon Carbide and Cordierite Diesel Particulate Filters Using a Copper Fuel Additive

1997-02-24
970187
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).
Technical Paper

A Theoretical and Experimental Study of the Regeneration Process in a Silicon Carbide Particulate Trap Using a Copper Fuel Additive

1997-02-24
970188
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.
Technical Paper

The Performance of a Spark-Ignited Stratified-Charge Two Stroke Engine Operating on a Kerosine Based Aviation Fuel

1997-09-08
972737
This study examines the feasibility of broadening the fuel capabilities of a direct-injected two-stroke engine with stratified combustion. A three cylinder, direct-injected two-stroke engine was modified to operate on JP-5, a kerosene-based jet fuel that is heavier, more viscous, and less volatile than gasoline. Demonstration of engine operation with such a fuel after appropriate design modifications would significantly enhance the utilization of this engine in a variety of applications. Results have indicated that the performance characteristics of this engine with jet fuel are similar to that of gasoline with respect to torque and power output at low speeds and loads, but the engine's performance is hampered at the higher speeds and loads by the occurrence of knock.
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