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A Cummins ISB 5.9 liter medium-duty engine with cooled EGR has been used to study an early extrusion of an advanced ceramic uncatalyzed diesel particulate filter (DPF). Data for the advanced ceramic material (ACM) and an uncatalyzed cordierite filter of similar dimensions are presented. Pressure drop data as a function of mass loadings (0, 4, and 6 grams of particulate matter (PM) per liter of filter volume) for various flow rate/temperature combinations (0.115 - 0.187 kg/sec and 240 - 375 °C) based upon loads of 15, 25, 40 and 60% of full engine load (684 N-m) at 2300 rpm are presented. The data obtained from these experiments were used to calibrate the MTU 1-D 2-Layer computer model developed previously at MTU. Clean wall permeability determined from the model calibration for the ACM was 5.0e-13 m2 as compared to 3.0e-13 m2 for cordierite.

A methodology to estimate the mass of particulate retained in a catalyzed particulate filter as a function of measured total pressure drop, volumetric flow rate, exhaust temperature, exhaust gas viscosity and cake and wall permeability applicable to real-time computation is discussed. This methodology is discussed from the view point of using it to indicate when to initiate active regeneration and as an On-Board Diagnostic tool to detect filter failures. Steady-state loading characterization experiments were conducted on a catalyzed diesel particulate filter (CPF) in a Johnson Matthey CCRT® (catalyzed continuously regenerating trap) system. The experiments were performed using a 10.8 L 2002 Cummins ISM heavy-duty diesel engine. Experiments were conducted at 20, 60 and 75% of full engine load (1120 Nm) and rated speed (2100 rpm) to measure the pressure drop, transient filtration efficiency, particulate mass balance, and gaseous emissions.

The effects of an oxidation catalytic converter (OCC), an emulsified fuel, and their combined effects on particle number and volume concentrations compared to those obtained when using a basefuel were studied. Particle size and particulate emission measurements were conducted at three operating conditions; idle (850 rpm, 35 Nm), Mode 11 (1900 rpm, 277 Nm) and Mode 9 (1900 rpm, 831 Nm) of the EPA 13 mode cycle. The individual effects of the emulsified fuel and the OCC as well as their combined effects on particle number and volume concentrations were studied at two different particle size ranges; the nuclei (less than or equal to 50 nm) and accumulation (greater than 50 nm) modes. An OCC loaded with 10 g/ft3 platinum metal (OCC1) and a 20% emulsified fuel were used for this study and a notable influence on the particle size with respect to number and volume distributions was observed.

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).

A one-dimensional, two layer computational model was developed to predict the behavior of a clean and particulate-loaded catalyzed wall-flow diesel particulate filter (CPF). The model included the mechanisms of particle deposition inside the CPF porous wall and on the CPF wall surface, the exhaust flow field and temperature field inside the CPF, as well as the particulate catalytic oxidation mechanisms accounting for the catalyst-assisted particulate oxidation by the catalytic coating in addition to the conventional particulate thermal oxidation. The paper also develops the methodology for calibrating and validating the model with experimental data. Steady state loading experiments were performed to calibrate and validate the model.

A computational lumped parameter model (MTU-Filter-Lumped) was developed to describe the performance of diesel particulate filters (DPFs) during loading and regeneration processes. The model was formulated combining three major sub-models: a filtration model, a pressure drop model, and a mass and an energy balance equation for the total filter volume. The first two sub-models have been widely validated in the literature, while the third sub-model is introduced and combined with the first two sub-models in the present study. The three sub-models combined can give a full description of diesel particulate filter behavior during loading and regeneration processes, which was the objective of the present work. The total combined lumped parameter model was calibrated using experimental data from the literature covering a range of experimental conditions, including different catalytic regeneration means and engine operating conditions.

Numerical modeling of aftertreatment systems has been proven to reduce development time as well as to facilitate understanding of the internal physical and chemical processes occurring during different operating conditions. Such a numerical model for a catalyzed diesel particulate filter (CPF) was developed in this research work which has been improved from an existing numerical model briefly described in reference. The focus of this CPF model was to predict the effect of the catalyst on the gaseous species concentrations and to develop particulate matter (PM) filtration and oxidation models for the PM cake layer and substrate wall so as to develop an overall model that accurately predicts the pressure drop and PM oxidized during passive oxidation and active regeneration. Descriptions of the governing equations and corresponding numerical methods used with relevant boundary conditions are presented.

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.

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.

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.

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 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.

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.

A numerical model to simulate the filtration and regeneration performance of catalyzed diesel particulate filters (CPFs) was developed at Michigan Technological University (MTU). The mathematical formulation of the model and some results are described. The model is a single channel (inlet and outlet) representation of the flow while the thermal and catalytic regeneration framework is based on a 2-layer approach. The 2-layer model can simulate particulate matter (PM) oxidation by thermal and ‘catalytic’ means of oxidation with O2. Several improvements were made to this basic model and are described in this paper. A model to simulate PM oxidation by NO2/Temperature entering the particulate filter and oxidizing the PM in the two layers of the PM cake was developed. This model can be used to simulate the performance of filters with catalyst washcoats and uncatalyzed filters placed downstream of diesel oxidation catalysts (DOCs), as in the continuously regenerating traps, CRT's®.

Modeling of diesel exhaust after-treatment devices is a valuable tool in the development and performance evaluation of these devices in a cost effective manner. Results from steady state loading experiments on a catalyzed particulate filter (CPF) in a Johnson Matthey CCRT®, performed with and without the upstream diesel oxidation catalyst (DOC) are described in this paper. The experiments were performed at 20, 40, 60 and 75% of full load (1120 Nm) at rated speed (2100 rpm) on a Cummins ISM 2002 heavy duty diesel engine. The data obtained were used to calibrate one dimensional (1-D) DOC and CPF models developed at Michigan Technological University (MTU). The 1-D 2-layer single channel CPF model helped evaluate the filtration and passive oxidation performance of the CPF. DOC modeling results of the pressure drop and gaseous emission oxidation performance using a previously developed model are also presented.

Heavy-duty diesel engine particulate matter (PM) emissions must be reduced from 0.1 to 0.01 grams per brake horsepower-hour by 2007 due to EPA regulations [1]. A catalyzed particulate filter (CPF) is used to capture PM in the exhaust stream, but as PM accumulates in the CPF, exhaust flow is restricted resulting in reduced horsepower and increased fuel consumption. PM must therefore be burned off, referred to as CPF regeneration. Unfortunately, nominal exhaust temperatures are not always high enough to cause stable self-regeneration when needed. One promising method for active CPF regeneration is to inject fuel into the exhaust stream upstream of an oxidation catalytic converter (OCC). The chemical energy released during the oxidation of the fuel in the OCC raises the exhaust temperature and allows regeneration.

A 1-D 2-layer model developed previously at MTU was used in this research to predict the pressure drop, filtration characteristics and various properties of the particulate filter and the particulate deposit layer. The model was calibrated and validated for this CPF with data obtained from steady state experiments conducted using a 1995 Cummins M11-330E heavy-duty diesel engine with manual EGR and using ULSF. The CPF used is a NGK filter having a cordierite substrate with NEX catalyst type formulation (54% porosity, 15.0 μm mean pore diameter and 50 gms/ft3 Pt). The filter was catalyzed using a wash coat process. The model was used to predict the pressure drop, particulate mass retained inside the CPF, particulate mass filtration efficiency and concentration downstream of the CPF with agreement between the experimental and simulated data.

The effect of fuel changes on diesel oxidation catalyst performance was studied by comparing the physical, chemical and biological character of the particulate emissions using three different fuels. Baseline (uncatalyzed) emissions were also compared for these same fuels. The fuels used for this study were: a typical No. 2 fuel, a No. 1 fuel, and a shale oil-derived diesel fuel. Comparisons of NOX, NO, NO2, HC and particulate mass emissions using each fuel were made using selected modes from the EPA 13 mode cycle. Changes in the chemical and biological character of the soluble organic fraction (SOF) were also studied. Fuel properties, most notably fuel sulfur content, were found to affect the performance of the oxidation catalyst used. Fuel sulfur content should be kept as low as possible if catalytic converters are used on diesel powered equipment.

The present study investigates the pressure drop and filtration characteristics of wall-flow diesel particulate monoliths, with the aid of a mathematical model. An analytic solution to the model equations describing exhaust gas mass and momentum conservation, in the axial direction of a monolith cell, and pressure drop across its porous walls has been obtained. The solution is in very good agreement with available experimental data on the pressure drop of a typical wall-flow monolith. The capture of diesel particles by the monolith, is described applying the theory of filtration through a bed of spherical collectors. This simple model, is in remarkable agreement with the experimental data, collected during the present and previous studies, for the accumulation mode particles (larger than 0.1 μm).

A model for calculating the trap pressure drop, various particulate properties, filtration characteristics and trap temperatures was developed during the steady-state and transient cycles using the theory originated by Opris and Johnson, 1998. This model was validated with the data obtained from the steady-state cycles run with an IBIDEN SiC diesel particulate filter. To evaluate the trap experimental filtration efficiency, raw exhaust samples were taken upstream and downstream of the trap. A trap scaling and equivalent comparison model was developed for comparing different traps at the same volume and same filtration area. Using the model, the trap pressure drop data obtained from different traps were compared equivalently at the same trap volume and same filtration area. The pressure drop performance of the IBIDEN SiC trap compared favorably to the previously tested NoTox SiC and the Cordierite traps.