Catalyzed Diesel Particulate Filter Research Articles

Experimental and Simulation Analysis of Temperature and Particulate Matter Distribution for a Catalyzed Diesel Particulate Filter

A multi-zone particulate filter (MPF) model from reference [1] was extended to analyze temperature and particulate matter (PM) distribution within each axial and radial zone of the filter substrate. A parametric study was used to determine the optimum required number of zones in the MPF model in the range of 5 × 5 to 20 × 20 zones for aftertreatment control applications. The MPF model with 10 × 10 zones was optimum and ran 12.2 times faster than real time. The 10 × 10 zone MPF model was calibrated using eighteen runs of data from a 2007 Cummins ISL engine that consisted of passive and active regeneration data sets for ultra-low-sulfur diesel (ULSD), diesel blend (ULSD) with 10 % biodiesel (B10), and diesel blend (ULSD) with 20 % biodiesel (B20) fuels. The MPF model was accurate, with maximum root mean square (RMS) error of 2.1 g for predicting PM loading and RMS error of within 10 °C for predicting temperature distribution within the filter. The PM distribution trends simulated by the MPF model were in good agreement with the experimental data measured using a terahertz wave scanner. The study of PM distribution during loading and at the end of PM oxidation (passive oxidation and active regeneration) showed that the PM oxidation by active regeneration leads to greater non-uniform PM loading of the filter compared to the passive oxidation as quantified using the uniformity index (UI) which was developed in the research to quantify the PM and temperature distribution.

Multi-catalytic soot filtration in automotive and marine applications

The emission of particulate matter (PM) and NOx from diesel engines has proven to have a negative influence on health, and future regulations will require more than 90% PM and NOx removal. For land-based trucks using low-sulfur fuels, a sequential catalyst system is foreseen consisting of an upstream diesel oxidation catalyst (DOC), a catalyzed diesel particulate filter (cDPF), and a downstream SCR NOx removal catalyst together with an ammonia slip catalyst (ASC). Urea is injected as a precursor for ammonia: engine→DOC→cDPF→Ureainj→SCR→ASC→out. The SCR function can with process advantage be integrated into the filter and reduce volume. The trapped soot in the cDPF must currently be combusted away. Three different soot combustion mechanisms are used: (1) passive soot regeneration by NO2, (2) combustion by direct catalyst soot contact, and (3) active soot regeneration with O2 at around 600°C. Full soot combustion by direct catalyst soot contact is not needed in a system as soot combustion by NO2 and O2 gases plays major roles. For marine vessels, no PM emission regulation exists today. The emission problem is especially severe for vessels using heavy-fuel oil (HFO) with up to 3.5% sulfur and high (heavy) metal content, fuel properties that until now have prevented a reliable PM removal process. Recently, however, a catalyst-assisted passive soot regeneration process above 350°C was developed including an “in situ” ash removal. This new process was validated on a ship using a sulfur-resistant Pd,V2O5 filter catalyst that combusts soot, CO, and HC including PAHs, and it is well suited as front end for an SOx scrubber.

Soot Oxidation Kinetics of Different Ceria Nanoparticle Catalysts

Catalysts for direct soot oxidation in catalyzed diesel particulate filters (CDPFs) consist typically of various mixed oxide compositions (frequently with CeO2 as the dominant component) that assist soot oxidation by enhancing the supply of oxygen from the catalyst to the soot. Apart from the composition, the material morphological characteristics may also contribute to the catalytic activity and this is the motivation for the present study. Different CeO2 nanoparticle catalysts have been obtained employing aerosol-based synthesis (ABS) and sol–gel methods. The obtained catalyst particles have been characterized with respect to their physical and morphological properties as well as with respect to their catalytic soot oxidation activity. The results have been analyzed with the aid of a multi-population kinetics model where soot is found to consist of three fractions reacting with different activation energies, namely 120, 180, and 240 kJ/mol. The occurrence of these three fractions is attributed to the formation of distinct families of surface oxygen complexes (SOCs) on the carbon surface which are subsequently gasified and hence cause soot oxidation, in agreement with accepted mechanisms of soot oxidation in the literature. The CeO2 nanoparticles oxidize catalytically all three fractions of soot, but with different “enhancement factors,” while the activation energies during catalytic oxidation remain the same. A comparison of the catalytic pre-exponentials to those of plain soot shows, in most cases, enhancements, which for some catalysts, can be up to ∼4.5, 6.5, and 2 times larger than those of plain soot, reflecting the relative capacity of the catalyst to generate more of the respective SOCs. The developed approach provides a more detailed but tractable way to describe soot oxidation (plain and catalytic), which can be readily incorporated into simulations of actual emission control systems to increase their reliability.

Modeling and simulation of soot combustion dynamics in a catalytic diesel particulate filter

In the work presented in this paper, a two-dimensional mathematical model of soot regeneration was developed for a single-channel catalytic diesel particulate filter. The commercial computational fluid dynamics (CFD) code ANSYS Fluent 15.0 was used to simulate the gas flow field, whereas the regeneration kinetics was implemented through user-defined-subroutines. Both mechanisms of catalyzed and non-catalyzed (i.e., thermal) oxidation were used to describe combustion of the soot trapped inside the porous wall of the filter. Conversely, only non-catalyzed oxidation was assumed for the cake layer. The aim of the work was at investigating the effect of the catalyst activity on the regeneration dynamics of the filter in the light of the thermal interaction between combustion of the soot in the (catalytic) porous wall and combustion of the cake. To this end, computations were run by increasing the pre-exponential factor in the Arrhenius equation for the catalytic reaction rate, thus simulating the effect of increasing catalyst activity.Numerical results have shown that, as the catalyst activity is increased, a transition occurs from a regime of slow combustion, in which regeneration proceeds in a substantially uniform manner over the filter, to a regime of intense combustion, in which regeneration proceeds by a reaction front moving upstream and downstream. The regime of slow combustion is characterized by low temperature rise (difference between the maximum filter temperature, Tmax, and the inlet gas temperature, Tin, lower than 100K) and long time for cake consumption and, thus, filter regeneration (~1800s). It is established when the catalyst activity is too low to appreciably affect combustion of the cake. Thus, combustion of the cake occurs independently of what happens in the porous wall of the filter. In contrast, the regime of intense combustion is characterized by high temperature rise – (Tmax−Tin)~400K – and short time for regeneration (~100s). It is established when the catalyst activity is high enough to make the porous wall of the filter an effective pilot for the cake. For this regime, the highest temperature rise is found under conditions that maximize the synchronization between combustion of the soot in the porous wall of the filter and combustion of the cake. When such a synchronization is attained, the time for filter regeneration becomes substantially insensitive to variations in the catalyst activity.

High NO2/NOx emissions downstream of the catalytic diesel particulate filter: An influencing factor study

Diesel vehicles are responsible for most of the traffic-related nitrogen oxide (NOx) emissions, including nitric oxide (NO) and nitrogen dioxide (NO2). The use of after-treatment devices increases the risk of high NO2/NOx emissions from diesel engines. In order to investigate the factors influencing NO2/NOx emissions, an emission experiment was carried out on a high pressure common-rail, turbocharged diesel engine with a catalytic diesel particulate filter (CDPF). NO2 was measured by a non-dispersive ultraviolet analyzer with raw exhaust sampling. The experimental results show that the NO2/NOx ratios downstream of the CDPF range around 20%–83%, which are significantly higher than those upstream of the CDPF. The exhaust temperature is a decisive factor influencing the NO2/NOx emissions. The maximum NO2/NOx emission appears at the exhaust temperature of 350°C. The space velocity, engine-out PM/NOx ratio (mass based) and CO conversion ratio are secondary factors. At a constant exhaust temperature, the NO2/NOx emissions decreased with increasing space velocity and engine-out PM/NOx ratio. When the CO conversion ratios range from 80% to 90%, the NO2/NOx emissions remain at a high level.

Regulated and unregulated emissions from modern 2010 emissions-compliant heavy-duty on-highway diesel engines

The U.S. Environmental Protection Agency (EPA) established strict regulations for highway diesel engine exhaust emissions of particulate matter (PM) and nitrogen oxides (NOx) to aid in meeting the National Ambient Air Quality Standards. The emission standards were phased in with stringent standards for 2007 model year (MY) heavy-duty engines (HDEs), and even more stringent NOX standards for 2010 and later model years. The Health Effects Institute, in cooperation with the Coordinating Research Council, funded by government and the private sector, designed and conducted a research program, the Advanced Collaborative Emission Study (ACES), with multiple objectives, including detailed characterization of the emissions from both 2007- and 2010-compliant engines. The results from emission testing of 2007-compliant engines have already been reported in a previous publication. This paper reports the emissions testing results for three heavy-duty 2010-compliant engines intended for on-highway use. These engines were equipped with an exhaust diesel oxidation catalyst (DOC), high-efficiency catalyzed diesel particle filter (DPF), urea-based selective catalytic reduction catalyst (SCR), and ammonia slip catalyst (AMOX), and were fueled with ultra-low-sulfur diesel fuel (~6.5 ppm sulfur). Average regulated and unregulated emissions of more than 780 chemical species were characterized in engine exhaust under transient engine operation using the Federal Test Procedure cycle and a 16-hr duty cycle representing a wide dynamic range of real-world engine operation. The 2010 engines’ regulated emissions of PM, NOX, nonmethane hydrocarbons, and carbon monoxide were all well below the EPA 2010 emission standards. Moreover, the unregulated emissions of polycyclic aromatic hydrocarbons (PAHs), nitroPAHs, hopanes and steranes, alcohols and organic acids, alkanes, carbonyls, dioxins and furans, inorganic ions, metals and elements, elemental carbon, and particle number were substantially (90 to >99%) lower than pre-2007-technology engine emissions, and also substantially (46 to >99%) lower than the 2007-technology engine emissions characterized in the previous study.Implications: Heavy-duty on-highway diesel engines equipped with DOC/DPF/SCR/AMOX and fueled with ultra-low-sulfur diesel fuel produced lower emissions than the stringent 2010 emission standards established by the U.S. Environmental Protection Agency. They also resulted in significant reductions in a wide range of unregulated toxic emission compounds relative to older technology engines. The increased use of newer technology (2010+) diesel engines in the on-highway sector and the adaptation of such technology by other sectors such as nonroad, displacing older, higher emissions engines, will have a positive impact on ambient levels of PM, NOx, and volatile organic compounds, in addition to many other toxic compounds.

Development of a Catalyzed Diesel Particulate Filter Multi-zone Model for Simulation of Axial and Radial Substrate Temperature and Particulate Matter Distribution

The catalyzed particulate filter (CPF) is an important exhaust aftertreatment subsystem that is managed by the electronic control unit (ECU) of an engine. CPFs need periodic regeneration to avoid temperature exotherms and excess engine back pressure. To this end, a multi-zone particulate filter (MPF) model was developed in this research to serve as a simulation tool to provide on-board diagnostics (OBD) data for managing CPF active regeneration (AR). The MPF model runs in real time within the ECU to provide feedback on temperature and particulate matter (PM) loading distribution within each axial and radial zone of the filter substrate. The MPF model accounts for the internal and external heat transfer mechanisms, inlet temperature distribution using the fully developed boundary layer concept, and PM oxidation by thermal (O2)- and NO2-assisted oxidation mechanisms. A calibration procedure was developed to calibrate the PM kinetics and heat transfer coefficients of the MPF model. The model shows the good capability to predict temperature and PM loading distribution within the filter.

Nanostructured platinum catalyst coating on diesel particulate filter with a low-cost electroless deposition approach

To meet an increasingly stringent regulation in suppression of particulate matter (PM) in exhaust stream, catalytic diesel particulate filter (cDPF) is a promising solution that catalytically converts carbon agglomerate to gaseous emissions, releasing to atmosphere without particular caution. A low-cost electroless coating approach is presented here to realize in situ growth of nanostructured metal crystals inside micropores without the need of electrical contacts and regardless of the substrate’s chemical property. SEM and X-ray spectroscopy (EDX) showed that silver (Ag) precursor gives rise to well-dispersed Pt particles on the multi-walled support with low aggregation and high surface density. Catalytic performance on this metallized filter is quantitatively weighed by thermal gravity analysis (TGA), which exhibits the drastic difference between bare soot and presence of Pt nanoparticles. In addition, the participation of NOx significantly reduced the soot ignition temperature, provided that involving of oxidase gas triggers the distinct pathway of catalytic reaction. Overall, the developed protocol paves a new avenue for chemically embedding nanostructured Pt catalysts in micrometric hollow reactors, producing a large-scale catalytic surfaces for soot combustion and well-balancing the economic and technical needs.

Experimental study on filtration and continuous regeneration of a particulate filter system for heavy-duty diesel engines

This study investigated the filtration and continuous regeneration of a particulate filter system on an engine test bench, consisting of a diesel oxidation catalyst (DOC) and a catalyzed diesel particulate filter (CDPF). Both the DOC and the CDPF led to a high conversion of NO to NO2 for continuous regeneration. The filtration efficiency on solid particle number (SPN) was close to 100%. The post-CDPF particles were mainly in accumulation mode. The downstream SPN was sensitively influenced by the variation of the soot loading. This phenomenon provides a method for determining the balance point temperature by measuring the trend of SPN concentration.

Catalytic DPF microwave assisted active regeneration

In the last decades, diesel engines have attracted an increasing interest from vehicles producer and public, due to their higher thermal efficiency, less CO and unburned hydrocarbons emission, and longer lifetime comparing with gasoline engines. However, the high emission of soot particulates and NOx are still their key problems. The combination of filters and oxidation catalysts is one of the most effective after-treatment techniques to eliminate soot particles from the exhaust gases: the deposited catalyst lowers the soot ignition temperature from 550°C (uncatalyzed reaction) to the typical values of diesel exhaust gases (180–400°C).In our previous works we showed that the simultaneous use of a microwave (MW) applicator and a specifically catalyzed Diesel Particulate Filter (DPF), loaded up to 20wt% of Copper Ferrite (CuFe2O4), allows to reduce the temperature, the energy and the time required for the regeneration. Starting by these very promising results, in this work we continued to study in order to further improve the performances of the catalyzed DPF, reducing the temperature and minimizing the MW energy required for the regeneration. Furthermore we verified the feasibility of the MW technology by assessing the energy balance of the regeneration phase, comparing it to the actually employed regeneration technologies.

The remote oxidation of soot separated by ash deposits via silver–ceria composite catalysts

One of the main issues of catalyzed diesel particulate filter is ash deposition onto catalyst coated on the filter. The effects of ash deposition on the catalysis of soot oxidation with gaseous oxygen were determined using multi-layered samples composed of a catalyst, an ash material and soot particles deposited on a thin cordierite plate in sequence. Catalysts composed of silver and ceria were used to enhance the oxidation of soot particles separated from the catalyst by ash deposits of either alumina or calcium sulfate. The effectiveness of remote soot oxidation was found to extend across an ash thickness of more than 50μm for both ash materials, although a catalyst composed only of ceria did not show any catalytic performance for remote soot oxidation. Using an 18O/16O isotopic exchange reaction and electron spin resonance techniques, a possible mechanism for this phenomenon was proposed, whereby a superoxide ion (O2−) species generated on the catalyst surface first migrates to the ash surface and then to the soot particles, which it subsequently oxidizes.

Gas- and particle-phase primary emissions from in-use, on-road gasoline and diesel vehicles

Tailpipe emissions from sixty-four unique light-duty gasoline vehicles (LDGVs) spanning model years 1987–2012, two medium-duty diesel vehicles and three heavy-duty diesel vehicles with varying levels of aftertreatment were characterized at the California Air Resources Board Haagen-Smit and Heavy-Duty Engine Testing Laboratories. Each vehicle was tested on a chassis dynamometer using a constant volume sampler, commercial fuels and standard duty cycles. Measurements included regulated pollutants such as carbon monoxide (CO), total hydrocarbons (THC), nitrogen oxides (NOx), and particulate matter (PM). Off-line analyses were performed to speciate gas- and particle-phase emissions. The data were used to investigate trends in emissions with vehicle age and to quantify the effects of different aftertreatment technologies on diesel vehicle emissions (e.g., with and without a diesel particulate filter). On average, newer LDGVs that met the most recent emissions standards had substantially lower emissions of regulated gaseous pollutants (CO, THC and NOx) than older vehicles. For example, THC emissions from the median LDGV that met the LEV2 standard was roughly a factor of 10 lower than the median pre-LEV vehicle; there were also substantial reductions in NOx (factor of ∼100) and CO (factor of ∼10) emissions from pre-LEV to LEV2 vehicles. However, reductions in LDGV PM mass emissions were much more modest. For example, PM emission from the median LEV2 vehicle was only a factor of three lower than the median pre-LEV vehicle, mainly due to the reductions in organic carbon emissions. In addition, LEV1 and LEV2 LDGVs had similar PM emissions. Catalyzed diesel particulate filters reduced CO, THC and PM emissions from HDDVs by one to two orders of magnitude. Comprehensive organic speciation was performed to quantify priority air toxic emissions and to estimate the secondary organic aerosol (SOA) formation potential. The data suggest that the SOA production from cold-start LDGVs exhaust will likely exceed primary PM emissions from LDGVs and could potentially exceed SOA formation from on-road diesel vehicles.

Preparation and Application of Perovskite Catalysts for Diesel Soot Emissions Control: An Overview

The diesel engines are energy efficient (1), but their particulate matter (soot) emissions are still a matter of concern even though major advances in their control are being made. For soot abatement, catalytic diesel particulate filter (DPF) technique is widely employed to trap and burn the soot. Many types of catalysts have been investigated for the soot combustion i.e. platinum group metal (PGM) based, perovskite-type oxides, spinel-type oxides, rare earth metal oxides, and mixed transient metal oxides etc. The cost of PGM catalysts is high and their availability is questionable. Further they are susceptible to poisoning and have low thermal stability. On the other hand perovskite catalysts show potential as effective soot oxidation catalyst for the DPF because of their low cost, high thermal stability and tailoring flexibility. Many papers related to soot oxidation over perovskite catalysts have been published but no review paper appears in the literature that is dedicated to soot oxidation. Thus, this article provides a summary of published information regarding pure and substituted perovskite catalyst, preparation methods, properties, and their application for diesel soot emission control.

Development of a light vehicle diesel aftertreatment system with DOC DPF and urea SCR

Meeting stringent emission regulations is a challenge to light vehicle diesel engines because of complexities of aftertreatment system, packaging constraints, and emission regulations. This article intends to introduce development philosophy from developing a light vehicle aftertreatment system that includes diesel oxidisation catalyst (DOC), catalytic diesel particulate filter (CDPF), urea injector and urea selective catalytic reduction (SCR). The development focus was on overall component planning to meet system emission targets at the early stage, system geometrical optimisations to meet pressure target at the intermediate stage, and design improvements of urea SCR module at the final stage. Both tests and modelling were employed seamlessly to reach decisions on major design directions. Significant efforts were spent on SCR mixing optimisation. Multiple mixer concepts were explored; the final developed SCR system was tested and able to meet all performance objectives. The roles of computational fluid dynamics (CFD) spray modelling and emission tests are discussed.

Experimental study of hexagonal and square diesel particulate filters under controlled and uncontrolled catalyzed regeneration

Although diesel engines have high thermal efficiency, large amounts of PM (particulate matter) including soot are emitted. A wall-flow DPF (diesel particulate filter) is one of the most important technologies for diesel emission control. However, the soot accumulation inside the DPF causes an increase of pressure loss. Then, the accumulated diesel soot needs to be burned, which is called a filer regeneration process. In this study, we have investigated the soot combustion on bare and catalyzed DPFs under controlled and uncontrolled regeneration. Two types of DPFs with conventional square and hexagonal cells were used. Results show that, in comparison with the bare DPF, the regeneration efficiency of the catalyzed DPF is clearly higher, indicating a marked effect of catalysts. Independent of regeneration temperature, a greater increase in the regeneration efficiency of the catalyzed DPF was confirmed under controlled regeneration. On the other hand, under uncontrolled regeneration, the maximum temperature of the catalyzed DPF is higher than that of the bare DPF, and it is reached shorter times. Interestingly, by comparing the conventional square cell DPF, the soot oxidation of the hexagonal cell DPF is promoted under controlled and uncontrolled regeneration.

Study of the catalyst load for a microwave susceptible catalytic DPF

The development of a fast, safe and cost effective Diesel Particulate Filter (DPF) regeneration procedure is the major remaining technological challenge in the use of this device. In our previous works we showed that the simultaneous use of a MW applicator and a specifically catalyst loaded DPF, with 15%wt of CuFe2O4, allows to reduce the temperature, the energy and the time required for the DPF regeneration. Starting by these very promising results, in this work we continued to study in order to further improve the performances of the catalyzed DPF in terms of catalytic activity, to reduce the temperature and the MW energy required for the regeneration. The objectives of this work are to optimize the preparation procedure of the catalytic DPF, to study the effect of the active species load, and to verify the feasibility of the MW technology by assessing the energy balance of the regeneration phase, comparing it to the actually employed regeneration technologies. In the future we want to evaluate the activity toward the other pollutants present in the diesel exhausts (such as NOx).

On-Road Gaseous Emission Characteristics of the Bus Based on DOC + CDPF Technology

In this paper, an experimental investigation was conducted using Vehicle Emission Testing System to study on-road gaseous emissions (CO, THC, NOX, CO2) characteristics based on diesel oxidation catalyst (DOC) and catalyzed diesel particulate filter (CDPF) technology. The results show that after the implementation of DOC + CDPF device, CO, THC emissions are significantly reduced, while the NOX, CO2 emissions remain almost the same. Under steady conditions, the reduction percentages of CO, THC, NOX, CO2 emission factors are 56.0%, 66.0%, 18.3%, 17.5%, respectively. Under transient operation conditions, the reduction percentages of CO, THC, NOX, CO2 emission factors are found to be 43.2%, 65.9%, 13.7%, 10.9%, respectively. Addition to the THC emission factor, the emission factors of CO, NOX and CO2 in transient operation conditions are higher than steady conditions.

Nitrogen Dioxide and Ultrafine Particles Dominate the Biological Effects of Inhaled Diesel Exhaust Treated by a Catalyzed Diesel Particulate Filter

We studied the impact of a catalyzed diesel particulate filter (DPF) on the toxicity of diesel exhaust. Rats inhaled exhaust from a Cummins ISM heavy-duty diesel engine, with and without DPF after-treatment, or HEPA-filtered air for 4h, on 1 day (single exposure) and 3 days (repeated exposures). Biological effects were assessed after 2h (single exposure) and 20h (single and repeated exposures) recovery in clean air. Concentrations of pollutants were (1) untreated exhaust (-DPF), nitric oxide (NO), 43 ppm; nitrogen dioxide (NO2), 4 ppm; carbon monoxide (CO), 6 ppm; hydrocarbons, 11 ppm; particles, 3.2×10(5)/cm(3), 60-70nm mode, 269 μg/m(3); (2) treated exhaust (+DPF), NO, 20 ppm; NO2, 16 ppm; CO, 1 ppm; hydrocarbons, 3 ppm; and particles, 4.4×10(5)/cm(3), 7-8nm mode, 2 μg/m(3). Single exposures to -DPF exhaust resulted in increased neutrophils, total protein and the cytokines, growth-related oncogene/keratinocyte chemoattractant, macrophage inflammatory protein-1α, and monocyte chemoattractant protein-1 in lung lavage fluid, as well as increased gene expression of interleukin-6, prostaglandin-endoperoxide synthase 2, metallothionein 2A, tumor necrosis factor-α, inducible nitric oxide synthase, glutathione S-transferase A1, heme oxygenase-1, superoxide dismutase 2, endothelin-1 (ET-1), and endothelin-converting enzyme-1 in the lung, and ET- 1 in the heart. Ratio of bigET-1 to ET-1 peptide increased in plasma in conjunction with a decrease in endothelial nitric oxide synthase gene expression in the lungs after exposure to diesel exhaust, suggesting endothelial dysfunction. Rather than reducing toxicity, +DPF exhaust resulted in heightened injury and inflammation, consistent with the 4-fold increase in NO2 concentration. The ratio of bigET-1 to ET-1 was similarly elevated after -DPF and +DPF exhaust exposures. Endothelial dysfunction, thus, appeared related to particle number deposited, rather than particle mass or NO2 concentration. The potential benefits of particulate matter reduction using a catalyzed DPF may be confounded by increase in NO2 emission and release of reactive ultrafine particles.

Simulated Fuel Economy and Emissions Performance during City and Interstate Driving for a Heavy-Duty Hybrid Truck

We compare simulated fuel economy and emissions for both conventional and hybrid class 8 heavy-duty diesel trucks operating over multiple urban and highway driving cycles. Both light and heavy freight loads were considered, and all simulations included full aftertreatment for NOx and particulate emissions controls. The aftertreatment components included a diesel oxidation catalyst (DOC), urea-selective catalytic NOx reduction (SCR), and a catalyzed diesel particulate filter (DPF). Our simulated hybrid powertrain was configured with a pre-transmission parallel drive, with a single electric motor between the clutch and gearbox. A conventional HD truck with equivalent diesel engine and aftertreatment was also simulated for comparison. Our results indicate that hybridization can significantly increase HD fuel economy and improve emissions control in city driving. However, there is less potential hybridization benefit for HD highway driving. A major factor behind the reduced hybridization benefit for highway driving is that there are fewer opportunities to utilize regenerative breaking. Our aftertreatment simulations indicate that opportunities for passive DPF regeneration are much greater for both hybrid and conventional trucks during highway driving due to higher sustained exhaust temperatures. When passive DPF regeneration is extensively utilized, the fuel penalty for particulate control is virtually eliminated, except for the 0.4%-0.9%more » fuel penalty associated with the slightly higher exhaust backpressure.« less

Effect of Biofuels on Catalyzed Diesel Particulate Filter Regeneration

Under the terms of the Renewable Energy Directive, EU member states are required to use 10 % of transport energy sourced from renewable sources, mainly biofuels, by 2020. The purpose is to reduce greenhouse gas (GHG) emissions from the transport sector. However, biodiesel used as fuel has a significant impact on emissions, as related by most of the literature on the subject. In particular, nitric oxides (NOx) and particulate matter (PM) emissions from current diesel technologies are critical factors because they are already close to the limits permitted by regulations and both limits will be even more stringent in the near future. Soot particles are trapped on a diesel particulate filter (DPF). If the DPF is catalyzed like in this study, the soot is then burned by reaction with NO2 (CDPF continuous regeneration) which occurs at lower temperatures than reaction with O2 (active regeneration). Tests of ultra-low sulfur diesel blended with rapeseed-biodiesel at 30 % (B30) and Fischer–Tropsch diesel (FT30) were conducted. The Fischer–Tropsch diesel was chosen to represent a biomass-to-liquid fuel. This work investigated the impact of these two biofuels on engine polluting emissions and the resulting CDPF ability to regenerate. When compared with similar inlet conditions on a synthetic gas bench, an impact of fuel was observed on soot reactivity: the CDPF loaded with FT30 soot regenerated slightly faster. Engine bench tests were also performed to combine the effects of fuel on engine emissions and soot reactivity and to evaluate the CDPF. The increase in NOx and decrease in PM emissions observed for B30 appeared to significantly improve CDPF continuous regeneration by NO2.