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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

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

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

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 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.
Technical Paper

A Statistical Approach to Determining the Effects of Speed, Load, Oil and Coolant Temperature on Diesel Engine Specific Fuel Consumption

1978-02-01
780971
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.
Technical Paper

The Development and Application of Ferrography to the Study of Diesel Engine Wear

1978-02-01
780181
This paper covers the development of Ferrographic oil analysis techniques for the study of diesel engine wear. A brief overview of the various wear analysis techniques now commonly used in laboratory and field engine wear studies is discussed. Also included in this paper is an in depth description of the Ferrographic oil analysis techniques and the various applications of the techniques to the study of engine wear. A comparison of the commonly used wear measurement methods, Ferrography, spectroscopy and the radioactive tracer methods, and their abilities to measure wear is also discussed. A direct injection, 4-cycle, turbocharged diesel engine was used in the testing and data are presented indicating the abilities of the Ferrographic oil analysis techniques to detect changes in wear rates. The effects of operating time on engine oil and the effects of the variation of oil and coolant temperatures on engine wear is presented.
Technical Paper

The Characterization of the Hydrocarbon and Sulfate Fractions of Diesel Particulate Matter

1978-02-01
780111
One of the more objectionable aspects of the use of diesel engines has been the emission of particulate matter. A literature review of combustion flames, theoretical calculations and dilution tunnel experiments have been performed to elucidate the chemical and physical processes involved in the formation of diesel particulate matter. A comparative dilution tunnel study of diluted and undiluted total particulate data provided evidence supporting calculations that indicate hydro-carbon condensation should occur in the tunnel at low exhaust temperatures. The sample collection system for the measurement of total particulate matter and soluble sulfate in particulate matter on the EPA 13 mode cycle is presented. A method to correct for hydrocarbon interferences in the EPA barium chloranilate method for the determination of sulfate in particulate matter is discussed.
Technical Paper

The Physical and Chemical Character of Diesel Particulate Emissions-Measurement Techniques and Fundamental Considerations

1978-02-01
780108
The techniques used to characterize the chemical and physical nature of particulates in diesel exhaust emissions are reviewed. The emphasis is on understanding the broader aspects of the fundamental nature of not only diesel particulates, but particulate systems in general. Consideration is given to the special nature of particulates which make them significant pollutants and to the relative place of the diesel in the formation of man-made particles. The underlying combustion processes leading to carbon and sulfur based particulates are reviewed. The important variables in steps of the combustion processes which lead to particulate formation are considered, as well as major fuel and engine factors. Collection methods are examined with examples given from current diesel dilution techniques. Probes, sampling lines, and instrumentation are considered.
Technical Paper

The Characterization of the Soluble Organic Fraction of Diesel Particulate Matter

1979-02-01
790418
This paper is concerned with the demonstration of a methodology for chemically characterizing diesel particulate organic matter (POM) emissions. The procedure begins with a Soxhlet extraction of the POM with dichloromethane to obtain a soluble organic fraction (SOF). The acidic and basic portions of the SOF are isolated by liquid-liquid extraction techniques with aqueous base and aqueous acid, respectively. The neutral portion of the extract is separated into paraffin, aromatic, transitional and oxygenated fractions by column chromatography on silica gel. Two additional fractions, the ether insoluble and hexane insoluble fractions, are also separated by the procedure. Quantitative mass data are presented on the extraction and fractionation of twelve particulate samples from the exhaust of a medium-duty diesel engine collected in a dilution tunnel at a volume dilution ratio of 8 to 1.
Technical Paper

Analysis of the Physical Characteristics of Diesel Particulate Matter Using Transmission Electron Microscope Techniques

1979-02-01
790815
An Andersen Impactor was used to collect particulate samples in both the undiluted and diluted exhaust from a Caterpillar 3150 diesel engine operated on the EPA 13-mode cycle. A total of 24 samples were examined using the transmission electron microscope and approximately 300 photomicrographs were taken. The microscope analysis and photomicrographs revealed details concerning the physical characteristics of the particulate and permitted a direct visual comparison of the samples collected. The photomicrographs were used to obtain diameter measurements of the basic individual spherical particles that comprise the much larger aggregates/agglomerates. Nearly 11,000 basic particles were measured and the observed range of diameters was 70-1200 Å. The mean particle diameters in the undiluted and diluted exhaust samples were 479 Å and 436 Å respectively. respectively. A respectively. 436 A respectively.
Technical Paper

Pneumatic Atomization in an Annular Flow Nozzle

1987-02-01
870611
A simple geometry pneumatic atomizer which could be used on internal combustion engine was tested with water as the working fluid. The pneumatic atomizer consists of a cylindrical chamber with an orifice plate at the outlet end. Liquid flows down the chamber walls and onto the nozzle orifice plate as a film. Air flows down the center of the chamber. The interaction of the air and water, which occurs at the orifice, atomizes the water. Large droplets form near the nozzle orifice and break up as they go down stream. Variations in the droplet size occurred in the spray. When geometry and flow rates were varied, changes which decreased the water film thickness or increased the air velocity at the nozzle orifice yielded smaller droplets in the spray. Droplet size data was measured by Malvern Laser Particle Sizer.
Technical Paper

The Effect of Low Sulfur Fuel and a Ceramic Particle Filter on Diesel Exhaust Particle Size Distributions

1992-02-01
920566
Diesel exhaust particle size distributions were measured using an Electrical Aerosol Analyzer (EAA) with both conventional (0.31 wt. pet sulfur) and low sulfur fuel (0.01 wt pet sulfur) with and without a ceramic diesel particle filter (DPF). The engine used for this study was a 1988 heavy-duty diesel engine (Cummins LTA10-300) operated at EPA steady-state modes 9 and 11. The particle size distribution results indicated the typical bi-modal distribution; however, there were clear differences in the number of particles in each mode for all conditions. For the baseline conditions with no DPF, there was more than one order of magnitude greater number of particles in the nuclei mode for the conventional fuel as compared to the low sulfur fuel, while the accumulation modes for each fuel were nearly identical.
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