Diesel Particulate Filter Regeneration Research Articles

Preparation and regeneration of a catalytic diesel particulate filter

A 1% Pt on CeO 2-promoted PrCrO 3 perovskite catalyst has been synthesized over a wall-flow monolith by the in situ solution combustion synthesis (SCS) method. The role of the catalyst, highly active towards diesel particulate combustion, has been studied during the regeneration phase as a function of the inlet trap temperature at which the regeneration is induced. The final aim of this study is to improve the knowledge on the catalytic regeneration process, with reference to the main operating parameters, in order to optimize the fuel penalties during the regeneration and to minimize the CO 2 emissions added by the post-injection and combustion of fuel.

3D-Simulation of soot loading and regeneration of diesel particulate filters

3D-Simulation of soot loading and regeneration of diesel particulate filters

Carbon particulate matter incineration in diesel engine emissions using indirect nonthermal plasma processing

One of the promising applications of nonthermal plasma (NTP) for environmental cleanup technology is low-temperature oxidation or incineration of carbon particulate matter (PM) in diesel engine emissions. In this process, NO 2 and activated radical species induced by NTP can incinerate carbon PM trapped by a diesel particulate filter (DPF) at low temperature (< 300 °C). In the present study, an experiment was carried out on indirect NTP DPF regeneration for real diesel engine emissions comprising CO 2 of several per cent, hydrocarbons of several hundreds of ppm and moisture of several tens of percentages. It was confirmed that DPF regeneration is possible for a real diesel emission at a low temperature of 280 °C. The removal energy efficiency was estimated to be 0.82 g/kW h. This electric power range is sufficient to meet the recently proposed long-term national regulation for diesel automobiles in Japan.

Effect of Lubricant on the Formation of Heavy-Duty Diesel Exhaust Nanoparticles

The effect of lubricants on nanoparticle formation in heavy-duty diesel exhaust with and without a continuously regenerating diesel particulate filter (CRDPF) is studied. A partial flow sampling system with a particle size distribution measurement starting from 3 nm, approximately, is used. Tests are conducted using four different lubricant formulations, a very low sulfur content fuel, and four steady-state driving modes. A well-documented test procedure was followed for each test. Two different kinds of nanoparticle formation were observed, and both were found to be affected bythe lubricant but in differentway. Without CRDPF, nanoparticles were observed at low loads. No correlation between lubricant sulfur and these nanoparticles was found. These nanoparticles are suggested to form mainly from hydrocarbons. With CRDPF, installed nanoparticles were formed only at high load. The formation correlated positively with the lubricant (and fuel) sulfur level, suggesting that sulfuric compounds are the main nucleating species in this situation. Storage effects of CRDPF had an effect on nanoparticle concentration as the emissions of nanoparticles decreased over time.

A Benefit‐Cost Analysis of Retrofitting Diesel Vehicles with Particulate Filters in the Mexico City Metropolitan Area

In the Mexico City metropolitan area, poor air quality is a public health concern. Diesel vehicles contribute significantly to the emissions that are most harmful to health. Harmful diesel emissions can be reduced by retrofitting vehicles with one of several technologies, including diesel particulate filters. We quantified the social costs and benefits, including health benefits, of retrofitting diesel vehicles in Mexico City with catalyzed diesel particulate filters, actively regenerating diesel particulate filters, or diesel oxidation catalysts, either immediately or in 2010, when capital costs are expected to be lower. Retrofit with either type of diesel particulate filter or an oxidation catalyst is expected to provide net benefits to society beginning immediately and in 2010. At current prices, retrofit with an oxidation catalyst provides greatest net benefits. However, as capital costs decrease, retrofit with diesel particulate filters is expected to provide greater net benefits. In both scenarios, retrofit of older, dirtier vehicles that circulate only within the city provides greatest benefits, and retrofit with oxidation catalysts provides greater health benefits per dollar spent than retrofit with particulate filters. Uncertainty about the magnitude of net benefits of a retrofit program is significant. Results are most sensitive to values used to calculate benefits, such as the concentration-response coefficient, intake fraction (a measure of exposure), and the monetary value of health benefits.

A concept for advanced DPF regeneration

Wall-flow, high-efficiency diesel particulate filters (DPF) have proven to significantly reduce the PM emissions of diesel engines and will be seen in rapidly increasing numbers of European diesel passenger cars. The challenges ahead for these “active” DPF systems are their enhanced cost-effectiveness while not compromising on vehicle/engine performance and emission safety.

Infrared thermometry measurement of temperature distribution in the microwave regeneration of diesel particulate filters

Infrared thermometry was applied to study the temperature distribution in microwave heating of diesel particulate filters. In situ non-contact temperature measurement tests were conducted using an integrated four-channel fibre-optic infrared temperature measurement and a microwave heating system. Silica light pipes, which are transparent to electromagnetic fields, were used to collect the infrared radiation from specified locations inside a filter during heating. The temporal and spatial temperature distributions in four microwave-heated diesel particulate filters with different soot and catalyst loading conditions were measured. Experimental results show the non-uniform heating inside filters. Catalyst coating, soot loading, and microwave power level all affect the heating rate and temperature distribution. Using 1 kW of microwave power, heating for 600 s can raise the temperature above 200°C in the soot-laden, catalysed filter.

A diesel particulate filter regeneration model with a multi-step chemical reaction scheme

Diesel particulate filters (DPFs) are considered necessary in order to meet future global diesel engine emissions legislation. Various regeneration methods have been developed to clean DPFs by periodic oxidation of trapped particulate matter (soot). To achieve this goal, it is important to understand the fundamentals of the regeneration process. Previous soot oxidation regeneration models relied on tunable chemical kinetic parameters to achieve agreement between model and experimental results. In the work reported in this paper, a multistep chemical reaction scheme is incorporated in a model to study the thermal regeneration process. The regeneration model does not require tunable parameters and its results compare well with experimental findings. The effects on regeneration of various gas species are also studied, in addition to O2 and N2, such as CO and H2O that are present in the exhaust gas. The model is also used to demonstrate the effects of quenching the regeneration process and its impact on partial filter regeneration.

Catalytic Coatings for Active and Passive Diesel Particulate Filter Regeneration

This paper will give an overview how catalytic coatings are applied in diesel particulate filter systems to support filter regeneration by soot oxidation with nitrogen dioxide or oxygen. Catalytic coatings can be placed on a catalyst substrate in front of a diesel particulate filter, on a filter, or in a combined system on both. Strategies and conditions for successful filter regeneration of those systems will be discussed.

The effects of soot properties on the regeneration behaviour of wall-flow diesel particulate filters

In recent years, significant effort has been put into studying the regeneration process of diesel particulate filters (DPFs) either through experiments or modelling. However, less attention is paid to understanding the important influence of soot properties on the regeneration process. In this paper, for the first time, five fundamental soot properties, namely activation energy, frequency factor of the reaction, soot bulk density, porosity and mean soot particulate diameter, are investigated. Sensitivity analyses are carried out for each of these parameters based on a one-dimensional generalized DPF regeneration model. It is found that activation energy is the most important factor in the regeneration process, followed by frequency factor, bulk density, porosity and mean particulate size. In addition, the results also indicate that the concentration of exhaust gas oxygen has a significant influence on the role played by each parameter. This clearly shows the importance of gas diffusion in the regeneration process.

Diesel fuel vaporiser

The regeneration of diesel particulate filters by raising the exhaust temperature by the engine management has some serious weak points. These do not apply, if the unburned hydrocarbons are not added to the exhaust via the engine, but are introduced directly in the exhaust line. This article explains the concept developed by ArvinMeritor Emissions Technologies GmbH for a reliable and cost efficient regeneration of diesel particulate filters.

Use of external post-injection for regeneration of diesel particulate filters

The regeneration of diesel particulate filters over the entire map area is a great challenge for engine developers. Especially in applications where the particulate filter cannot be mounted under the bonnet for package reasons but only in an underfloor position, the high temperatures needed for filter regeneration can only be reached with major efforts. The concept study presented in this article was carried out by IAV GmbH and shows the potential of external post-injection for realising reliable filter regeneration, even under these adverse installation conditions.

Diesel Particulate Filter Regeneration: Control of Calibration?

Diesel particulate filters are an efficient means of reducing particulate emissions of diesel engines by orders of magnitude. The necessary periodical regeneration of these filter systems requires drastic changes in the engine management, notably in fuel and air path control, because the temperature levels required for regeneration are 200°-400°C above normal levels. The approach taken to address this problem is described in this paper. It is at the same time used to illustrate typical engine control challenges and explains why model-based control methods still find only limited application in powertrain control. In particular, the importance of feedforward control is stressed, leading to the question: Control or Calibration?

Flow distribution effects in the loading and catalytic regeneration of wall-flow diesel particulate filters

The study of catalytic regeneration characteristics of porous ceramic diesel particulate filters (DPFs) is of growing interest to industry as diesel soot emissions are limited by legislation to levels below 0.01 g/km (for passenger cars). More specifically, pressure drop computations and correlations are important factors employed in the design and control of diesel filter systems. However, in numerous cases, computations and models fail to match the experimentally observed evolution of soot combustion in the filter. In this paper, the role of flow maldistribution in this issue is investigated, by means of full-scale tests of the loading and regeneration behaviour of a particulate filter installed on a modern diesel engine run on catalyst-doped fuel. Loading tests were performed at three characteristic engine operation points with markedly different levels of engine exhaust gas mass flowrate. In these tests, it becomes apparent that complex flow maldistribution phenomena exist during the loading phase, which are not directly reflected by the behaviour of the pressure drop versus time curve. However, these phenomena are shown to affect the distribution of collected soot mass in the different channels of the filter and, consequently, the regeneration behaviour. The evolution of flow maldistribution was also studied in a number of regeneration experiments. It was confirmed that the variation of the volatile organic fraction in the filter and the associated partial catalytic regenerations at low temperatures interact with flow and soot maldistribution in a complex way. The conclusions from this study set the scene for future, more detailed investigations that are expected to improve understanding and modelling of diesel filter pressure drop and regeneration characteristics.

Multi-channel simulation of regeneration in honeycomb monolithic diesel particulate filters

In recent years advanced computational tools of diesel particulate filter (DPF) regeneration have been developed to assist in the systematic and cost-effective optimization of next generation particulate trap systems. In the present study, we employ a previously validated, state-of-the-art multichannel DPF simulator to study the regeneration process over the entire spatial domain of the filter. Particular attention is placed on identifying the effect of inlet cones and boundary conditions, filter can insulation and the dynamics of “hot spots” induced by localized external energy deposition. Lateral heat losses through the insulation and the periphery of the filter can, as captured by the magnitude of the Nusselt number, Nu, are detrimental to the effectiveness of the regeneration process. A filter can Nu number less than 10 and preferably less than 5 is a good design target for high regeneration efficiency. For the case studied, insulation of the inlet cones can lead to a gain of 30% in regeneration efficiency by eliminating radial temperature gradients at the inlet filter face. The multichannel simulator provides an instructive illustration of the well-appreciated effects of localized hot spot on filter regeneration: hot spots play a more significant role (spread over) when located near the entrance of the filter.

Low Temperature Soot Incineration of Diesel Particulate Filter Using Honeycomb Nonthermal Plasma

The regulation for the automotive diesel engine emission becomes severe every year, and more effective post-processing technology is desired especially on particulate matter (PM), such as carbon soots. Although the use of ceramic diesel particulate filter (DPF) is now a leading technology for PM removal, the problem exists on the soot incineration or regeneration at low temperature, especially at the cold start. In the present study, a regeneration of DPF was investigated using the low temperature atmospheric pressure nonthermal plasma. The method is to use the NO2 and radicals induced by the plasma reactor to burn carbon soots deposited on DPF. First, three types of DPF plasma reactors were constructed and the performance on the conversion of NO to NO2 was evaluated on various conditions. Regeneration experiment was further carried out using a DPF honeycomb nonthermal plasma reactor. As a result, it was confirmed that the pressure drop decreased only when the plasma was turned on and the regeneration temperature of DPF was less than 200°C.

Modeling of Diesel Particulate Filter Regeneration: Effect of Fuel-Borne Catalyst

Modeling of Diesel Particulate Filter Regeneration: Effect of Fuel-Borne Catalyst

Simulation of continuously regenerating diesel particulate filters in transient driving cycles

Forced by strict emission standards, interest in the reduction of particulate emissions becomes increasingly higher. Although the technology of diesel particulate filters (DPFs) has advanced impressively, especially during recent years, considerable technological challenges remain unsolved. The technology of NO2-assisted continuously regenerating diesel filters in conjunction with the upcoming availability of low sulphur diesel fuel represents a promising solution, especially for heavy duty engines. In the present paper, a transient modelling approach for the combined catalyst and DPF system is presented. This combined model is used to predict the regeneration performance of NO2-assisted regeneration systems in the transient conditions of a legislated European driving cycle. Although the model is based on global and approximate reaction schemes, the results illustrate the applicability of simulation tools in the process of optimizing certain important design parameters of the system, such as catalyst and particulate filter sizing and positioning, and catalyst activity requirements. It is expected that such engineering models will be valuable tools in the selection and design of such kind of systems, minimizing the testing effort and the associated costs.

Intra-layer temperature gradients during regeneration of diesel particulate filters

Wall-flow filters are worldwide recognized as the most efficient devices for the abatement of particulate emissions from automotive diesel engines. Mathematical models simulating the particulate thermal oxidation process in the filters are already applied for system optimization. This paper deals with the appropriateness of a specific assumption inherently used in all relevant published models, namely the temperature uniformity in the soot and wall layer. A new mathematical model is developed to predict the temperature gradients under various operating conditions. Based on the model results, it is shown that significant temperature gradients inside the soot layer may exist under some practical operating conditions. These conditions are associated with high flow rates and high soot loadings. In these cases, the uniform temperature assumption may lead to erroneous results for the prediction of the overall regeneration process. The error of this assumption is assessed as function of the soot porosity.

An approach towards risk assessment for the use of a synergistic metallic diesel particulate filter (DPF) regeneration additive

The motivations for legislation to set diesel emissions limits requiring the use of diesel particulate filters (DPF) are summarised. If the DPF is to be used, demonstration of regeneration (combustion of collected carbonaceous material) without additional emission problems is important. Potential metal emissions resulting from use of a synergistic Fe/Sr fuel-borne DPF regeneration catalyst are evaluated. Measurements over legislated drive cycle estimate the metals to comprise 1–2% of the solid material emitted, and the DPF to collect >99% of such material. Diesel particulate matter is used as a marker, and from existing air quality and emission inventory measurements, maximum conceivable increases of <1 ng m −3 and <250 pg m −3 for iron and strontium, respectively, are calculated. From environmental assessment levels, derived from occupational exposure limits, these are not significant. For humans, daily ingress of airborne Sr is estimated at 3.5 ng. This is small compared to the known Sr contents of lungs, blood and the daily diet. In the context of reductions of other metals, particulate matter and pollutant emissions, the overall assessment is that the use of these metals to enable use of a DPF allows significant net environmental benefit to be obtained.