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Technical Paper

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

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

An Experimental and Computational Study of the Pressure Drop and Regeneration Characteristics of a Diesel Oxidation Catalyst and a Particulate Filter

An experimental and computational study was performed to evaluate the performance of the CRT™ technology with an off-highway engine with a cooled low pressure loop EGR system. The MTU-Filter 1D DPF code predicts the particulate mass evolution (deposition and oxidation) in a diesel particulate filter (DPF) during simultaneous loading and during thermal and NO2-assisted regeneration conditions. It also predicts the pressure drop across the DPF, the flow and temperature fields, the solid filtration efficiency and the particle number distribution downstream of the DPF. A DOC model was also used to predict the NO2 upstream of the DPF. The DPF model was calibrated to experimental data at temperatures from 230°C to 550°C, and volumetric flow rates from 9 to 39 actual m3/min.
Technical Paper

An Experimental and Numerical Study of the Performance Characteristics of the Diesel Oxidation Catalyst in a Continuously Regenerating Particulate Filter

A one-dimensional model simulating the oxidation of CO, HC, and NO was developed to predict the gaseous emissions downstream of a diesel oxidation catalyst (DOC). The model is based on the conservation of mass, species, and energy inside the DOC and draws on past research literature. Steady-state experiments covering a wide range of operating conditions (exhaust temperatures, flow rates and gaseous emissions) were performed, and the data were used to calibrate and validate the model. NO conversion efficiencies of 50% or higher were obtained at temperatures between 300°C and 350°C. CO conversion efficiencies of 85% or higher and HC conversion efficiencies of 75% or higher were found at every steady state condition above 200°C. The model agrees well with the experimental results at temperatures from 200°C to 500°C, and volumetric flow rates from 8 to 42 actual m3/min.
Technical Paper

Ceramic Particulate Traps for Diesel Emissions Control - Effects of a Manganese-Copper Fuel Additive

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.
Technical Paper

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

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

Extended Kalman Filter Estimator for NH3 Storage, NO, NO2 and NH3 Estimation in a SCR

This paper focuses on the development of an Extended Kalman Filter for estimating internal species concentration and storage states of an SCR using NOX and NH₃ sensors. The motivation for this work was twofold. First, knowledge of internal states may be useful for onboard diagnostic strategy development. In particular, significant errors between the outlet NOX or NH₃ sensors, reconstructed from estimated states, and the measured NOX or NH₃ concentrations may aid OBD strategies that attempt to identify particular system failure modes. Second, the EKF described estimates not only stored ammonia but also NO, NO₂ and NH₃ gas concentrations within and exiting the SCR. Exploiting knowledge of the individual species concentrations, instead of lumping them together as NOX, can yield improved closed loop urea controller performance in terms of reduced urea consumption and better NOX conversion.
Technical Paper

Extended Kalman Filter to Estimate NO, NO2, Hydrocarbon and Temperatures in a DOC during Active Regeneration and Under Steady State Conditions

Diesel Oxidation Catalysts (DOC) are used on heavy duty diesel engine applications and experience large internal temperature variations from 150 to 600°C. The DOC oxidizes the CO and HC in the exhaust to CO2 and H2O and oxidizes NO to NO2. The oxidation reactions are functions of its internal temperatures. Hence, accurate estimation of internal temperatures is important both for onboard diagnostic and aftertreatment closed loop control strategies. This paper focuses on the development of a reduced order model and an Extended Kalman Filter (EKF) state estimator for a DOC. The reduced order model simulation results are compared to experimental data. This is important since the reduced order model is used in the EKF estimator to predict the CO, NO, NO2 and HC concentrations in the DOC and at the outlet. The estimator was exercised using transient drive cycle engine data. The closed loop EKF improves the temperature estimate inside the DOC compared to the open loop estimator.
Technical Paper

Oxidation Catalytic Converter and Emulsified Fuel Effects on Heavy-Duty Diesel Engine Emissions

A study was conducted to assess the effects of a water-diesel fuel emulsion with and without an oxidation catalytic converter (OCC) on steady-state heavy-duty diesel engine emissions. Two OCCs with different metal loading levels were used in this study. A 1988 Cummins L10-300 heavy-duty diesel engine was operated at the rated speed of 1900 rpm and at 75% and 25% load conditions (EPA modes 9 and 11 respectively) of the 13 mode steady-state test as well as at idle. Raw exhaust emissions' measurements included total hydrocarbons (HC), oxides of nitrogen (NOx) and nitric oxide (NO). Diluted exhaust measurements included total particulate matter (TPM) and its primary constituents, the soluble organic (SOF), sulfate (SO42-) and the carbonaceous solids (SOL) fractions. Vapor phase organic compounds (XOC) were also analyzed. The SOF and XOC samples were analyzed for selected polynuclear aromatic hydrocarbons (PAHs).
Technical Paper

Particulate Matter and Nitrogen Oxides Kinetics Based on Engine Experimental Data for a Catalyzed Diesel Particulate Filter

A numerical model to simulate the filtration and oxidation of PM as well as the oxidation of NO, CO and HC in a CPF was developed in reference [1]. The model consists of parameters related to filtration and oxidation of PM and oxidation of NO, CO and HC. One of the goals of this paper is to use the model to determine the PM and gaseous species kinetics for ULSD, B10 and B20 fuels using data from passive oxidation and active regeneration engine experimental studies. A calibration procedure to identify the PM cake and wall filtration parameters and kinetic parameters for the PM oxidation and NO, CO and HC oxidation was developed. The procedure was then used with the passive oxidation [2] and active regeneration [3] engine data. The tests were conducted on a 2007 Cummins ISL engine with a DOC and CPF aftertreatment system. The simulation results show good agreement with the experimental CPF pressure drop, PM mass retained measurements and the outlet NO, NO2, CO and HC concentrations.
Technical Paper

The Effect of a Diesel Oxidation Catalyst and a Catalyzed Particulate Filter on the Emissions from a Heavy Duty Diesel Engine

The objective of this research was to study the effects of a CCRT®, henceforth called Diesel Oxidation Catalyst - Catalyzed Particulate Filter (DOC-CPF) system on particulate and gaseous emissions from a heavy-duty diesel engine (HDDE) operated at Modes 11 and 9 of the old Environmental Protection Agency (EPA) 13-mode test cycle Emissions characterized included: total particulate matter (TPM) and components of carbonaceous solids (SOL), soluble organic fraction (SOF) and sulfates (SO4); vapor phase organics (XOC); gaseous emissions of total hydrocarbons (HC), carbon monoxide (CO), oxides of nitrogen (NOx), nitric oxide (NO) and nitrogen dioxide (NO2), oxygen (O2) and carbon dioxide (CO2); and particle size distributions at normal dilution ratio (NDR) and higher dilution ratio (HDR). Significant reductions were observed for TPM and SOL (>90%), SOF (>80%) and XOC (>70%) across the DOC-CPF at both modes.
Technical Paper

The Effects of Fuel Sulfur Concentration on Regulated and Unregulated Heavy-Duty Diesel Emissions

The effects of fuel sulfur concentration on heavy-duty diesel emissions have been studied at two EPA steady-state operating conditions, mode 9 (1900 RPM, 75% Load) and mode 11(1900 RPM, 25% Load). Data were obtained using one fuel at two sulfur levels (Low Sulfur, LS = 0.01 wt% S and Doped Low Sulfur DS = 0.29 wt% S). All tests were conducted using a Cummins LTA10-300 heavy-duty diesel engine. No significant changes were found for the nitrogen oxides (NOx), soluble organic fractions (SOF) and XAD-2 (a copolymer of styrene and divinylbenzene) organic component (XOC) due to the fuel sulfur level increase at either engine mode. The hydrocarbon (HC) levels were not significantly affected by sulfur at mode 9; however, at mode 11 the HC levels were reduced by 16%. The total particulate matter (TPM) levels increased by 17% at mode 11 and by 24% at mode 9 (both significantly different).
Technical Paper

The Effects of a Catalyzed Particulate Filter and Ultra Low Sulfur Fuel on Heavy Duty Diesel Engine Emissions

The objective of this research was to study the effect of a catalyzed particulate filter (CPF) with a high loading of catalyst (50 gms/ft3) and ultra low sulfur fuel (ULSF -0.57 ppm of sulfur) on the emissions from a heavy duty diesel engine. The particulate emissions were measured using two different analytical methods, i.e., the gravimetric method and the thermal optical method (TOM). The results from the two different methods of analyses were compared. The experiments were performed at four different operating conditions chosen from the old Environmental Protection Agency (EPA) 13-mode test cycle. A 1995 Cummins M11 heavy-duty engine with manually controlled exhaust gas recirculation (EGR) was used to perform the emission characterization experiments. The emission characterization included total particulate matter (TPM), which is composed of the solids (SOL), soluble organic fractions (SOF) and sulfates (SO4) analyzed using the gravimetric method.
Technical Paper

The Effects of a Porous Ceramic Particulate Trap on the Physical, Chemical and Biological Character of Diesel Particulate Emissions

Physical, chemical, and biological characterization data for the particulate emissions from a Caterpillar 3208 diesel engine with and without Corning porous ceramic particulate traps are presented. Measurements made at EPA modes 3,4,5,9,lO and 11 include total hydrocarbon, oxides of nitrogen and total particulate matter emissions including the solid fraction (SOL), soluble organic fraction (SOF) and sulfate fraction (SO4), Chemical character was defined by fractionation of the SOF while biological character was defined by analysis of Ames Salmonella/ microsome bioassay data. The trap produced a wide range of total particulate reduction efficiencies (0-97%) depending on the character of the particulate. The chemical character of the SOF was significantly changed through the trap as was the biological character. The mutagenic specific activity of the SOF was generally increased through the trap but this was offset by a decrease in SOF mass emissions.
Technical Paper

The Influence of a Low Sulfur Fuel and a Ceramic Particle Trap on the Physical, Chemical, and Biological Character of Heavy-Duty Diesel Emissions

This study was conducted to assess the effects of a low sulfur (<0.05 wt.%) fuel and an uncatalyzed ceramic particle trap on heavy-duty diesel emissions during both steady-state operation and during periods of electrically assisted trap regeneration. A Cummins LTA10-300 engine was operated at two steady-state modes with and without the trap. The exhaust trap system included a Corning EX-54 trap with an electrically assisted regeneration system. Both regulated emissions (oxides of nitrogen - NOx, total hydrocarbons - HC, and total particulate matter - TPM) and some unregulated emissions (polynuclear aromatic hydrocarbons - PAH soluble organic fraction - SOF, sulfates, vapor phase organics, and mutagenic activity) were measured during baseline, trap, and regeneration conditions. Emissions were collected with low sulfur (0.01 wt.%) fuel and compared to emissions with a conventional sulfur (0.32 wt.%) fuel. These fuels also varied in other fuel properties.
Technical Paper

The Measurement and Sampling of Controlled Regeneration Emissions from a Diesel Wall-Flow Particulate Trap

A diesel exhaust sampling system was specially designed to measure and collect emissions from a ceramic wall-flow particulate trap during periods of controlled electric regeneration with the exhaust emissions bypassing the trap. This resulted in the regeneration emissions being independent of those produced during either baseline (no control) or trap (exhaust filtration) sampling conditions. This system provided data regarding the physical, chemical, and biological character of regeneration emissions relative to baseline and trap emissions. Selected emission levels measured continuously during the regeneration process were also used to define the particle combustion process in the trap core. Variations in hydrocarbons (HC), oxides of nitrogen (NOx), and particulate volume concentrations during the regeneration process were used to define four stages of the combustion process: preheat; combustion wave formation; combustion wave propagation; and combustion wave extinction.