Author: Yujun Wang (Ph. D.) Publisher: ISBN: Category : Languages : en Pages : 137
Book Description
Diesel particulate filters (DPF) are devices that physically capture diesel particulates to prevent their release to the atmosphere. Diesel particulate filters have seen widespread use in on- and off-road applications as an effective means for meeting increasingly stringent particle emissions regulations. Although the soot deposit can be removed by regeneration, the incombustible material - ash, primarily derived from metallic additives in the engine lubricant, accumulates in the DPF channels with the increasing vehicle mileage or equivalent running hours. Ash accumulation inside filter increases the flow restriction and reduces the filter soot storage capacity, which results in higher filter regeneration frequencies and larger engine fuel penalty. Combined with experimental observations, DPF models are built to investigate the fundamental mechanisms of DPF aging process. The DPF soot and ash loading model, based on porous media filtration theory, is applied to understand the soot deposition across the substrate wall with soot and ash cake layer formation. DPF models are also used to investigate the process of ash transport and catalyst deactivation with increasing ash load level. DPF ash aging is found to have negative effect on passive regeneration due to the catalyst deactivation and diffusion resistance of ash cake layer. Besides, at given amount of ash load, the effects of ash spatial distribution on DPF performance are studied via simulation. It is found that the ash end plug has significant influences on DPF pressure drop while ash radial and axial distributions have minor effects. At known ash and substrate property, DPF performance can be optimized according the sensitivity map developed from this study. DPF model is beneficial to interpret the experimental observations and it is applied to predict the effects of certain factors, like flow rate and deposit level, on DPF performance. At the same time, modeling results are useful in optimizing the design of the combined engine-aftertreatment-lubricant system for future diesel engines and in understanding the requirements for robust aftertreatment systems.
Author: Michael James Bahr (Nav. E.) Publisher: ISBN: Category : Languages : en Pages : 92
Book Description
Diesel particulate filters (DPF) have seen widespread growth as an effective means for meeting increasingly rigorous particle emissions regulations. There is growing interest to exploit passive regeneration of DPFs to reduce fuel consumption accompanying traditional active regeneration. Incombustible material or ash, mainly derived from metallic additives in the engine lubricant, accumulates in the DPF over time. This ash accumulation increases flow restriction and rise in pressure drop across the DPF. The growth of pressure drop adversely impacts engine performance and fuel economy. This study built upon previous research to evaluate the different effects of regeneration strategy on ash packing and distribution within DPFs. Since passive regeneration relies on a catalyzed reaction, the interactions of ash with the catalyst will play an important role. Passive regeneration is specifically dependent on exhaust feed gas composition, exhaust conditions including temperature and flow rate, catalyst type and configuration, and the state of DPF loading during prior to passive regeneration. The goal of the study is to address the long-term effects of regeneration parameters on ash accumulations and the resulting impact of ash on the DPF catalyst performance. Experiments were conducted that focused on pressure drop measurements over the lifetime of diesel particulate filters with different regeneration methods coupled with post mortem ash characterization. These experiments provide insight to how these regeneration methods impact the DPF performance. These results, among few fundamental data of this kind, correlate changes in diesel particulate filter performance with exhaust conditions, regeneration strategy, and ash morphological characteristics. Outcomes are useful in optimizing the design of the combined engine-aftertreatment- lubricant system for future diesel engines, balancing the necessities of additives for adequate engine protection with the requirements for robust aftertreatment systems.
Author: Timothy V Johnson Publisher: SAE International ISBN: 0768096340 Category : Technology & Engineering Languages : en Pages : 374
Book Description
Until recently, the complexity of the Diesel Particulate Filter (DPF) system has hindered its commercial success. Stringent regulations of diesel emissions has lead to advancements in this technology, therefore mainstreaming the use of DPFs in light- and heavy-duty diesel filtration applications. This book covers the latest and most important research in DPF systems, focusing mainly on the advancements of the years 2002-2006. Editor Timothy V. Johnson selected the top 29 SAE papers covering the most significant research in this technology.
Author: Gregory James Monahan Publisher: ISBN: Category : Languages : en Pages : 99
Book Description
As a result of increasingly stringent emissions regulations, Diesel Particulate Filters (DPF) have become a widespread method of reducing particulate emissions in both on and off highway diesel engine use. This particular aftertreatment system is chosen for its high filtration efficiency and relative simplicity. The porous ceramic substrate captures the particulate matter which is comprised of combustible soot and inorganic metallic ash. While the soot can be cleared from the filter through high temperature oxidation, the small amount of ash remains in the filter. The presence of these soot and ash particles creates an increase in the flow resistance of the filter which creates more backpressure on the engine and results in a decrease in fuel economy. Over the life of the filter, the ash particles become a significant portion of particulate matter in the filter and the resulting flow resistance. While the effects of ash and soot on filter performance have been extensively studied, the underlying deposition mechanisms and effects of various ash properties are not well understood. The focus of this research is to investigate the effects of ash properties such as packing density and chemistry on the flow resistance of both the ash cake layer and the filter substrate. The results of this and other research can support the optimization of operating conditions, regeneration strategies, and lubricant additive formulations for decreased system backpressure. Additionally, this research seeks to develop and improve advanced diagnostic tools in order to bridge the gap between macro scale quantifiable flow resistance and micro scale deposition characteristics. Using both high resolution X-Ray CT imaging and flow simulation tools, a method is tested by which values for ash and filter permeability can be calculated to investigate local micro scale filter phenomena or various lab and field samples.
Author: Ryan Michael Morrow Publisher: ISBN: Category : Languages : en Pages : 62
Book Description
Diesel particulate filters (DPF) are currently widely used in various applications as a means of collecting particulate matter in order to meet increasingly stringent particle emissions regulations. Over time, the DPF slowly accumulates incombustible material or ash, mostly from the metallic additives present in the engine lubricant. This build up of accumulated ash leads to an increase in flow restriction and therefore an increase in pressure drop along the DPF. The increased pressure drop negatively impacts engine performance and fuel economy, and it also requires eventual filter removal for ash cleaning. While the major effects of ash accumulation on DPF performance are known, the fundamental underlying mechanisms are not. This work is focused on understanding key mechanisms, such as the soot deposition and the ash formation, accumulation, and distribution processes, which play a major role in determining the magnitude of the ash effect on DPF pressure drop. More specifically, it explores the location of ash deposit accumulation inside the DPF channels, whether in a layer along the filter walls or packed in a plug at the rear of the channels, which is one of the key factors controlling DPF pressure drop. A specialized experiment was set up by running three different lubricants, each with its own unique additive tracer, sequentially through a diesel burner system. Scanning electron microscopy (SEM) was used to analyze the evolution of the ash deposits in the DPF samples in order to explain the specific mechanisms and processes controlling ash properties and their effect on DPF pressure drop. The experimental results were compared and correlated with previous DPF test data and theoretical models, providing additional insight to optimize diesel particulate filter performance. The results are useful in optimizing the design of the engine, aftertreatment, and lubricant systems for future diesel engines, balancing the requirements of additives for adequate engine protection with the requirements for robust after treatment systems.
Author: Mengting Yu Publisher: ISBN: Category : Chemical engineering Languages : en Pages :
Book Description
Diesel engines are widely used because of their high efficiency and low “greenhouse gas” emission. The particulate matter (PM) emitted by a diesel engine is collected and then burned in a diesel particulate filter (DPF). Analysis and modeling works have been done in this research to provide insight on optimization of the DPF design and operating conditions to achieve low pressure drop across the filter to decrease fuel consumption and low peak temperature during regeneration to avoid filter melting, cracking, and/or catalyst deactivation. Limiting models of the 1-D two-channel DPF model are analyzed. Analytical predictions and physical insight on the filtration velocity, pressure drop, heat transfer, light-off and regeneration in a DPF are obtained. The hydraulic analysis enables an efficient optimization of the DPF that lead to a more uniform PM deposition profile and a decrease of the pressure drop. The heat transfer, light-off and regeneration analysis enable estimations of the DPF heat-up time, the speed and width of the temperature front, the light-off temperature and time, and the peak regeneration temperature. New DPF regeneration procedures are proposed to limit the maximum local temperature rise. In various cases a DPF is connected by a wide-angled cone (diffuser) to the engine exhaust pipe. A 2-D axisymmetric PM deposition and regeneration model is developed to investigate the impact of the inlet cone on the deposition rate and the regeneration temperature as well as on the transient inlet velocity distribution among the various DPF channels. The highest regeneration temperature and thermal stress when using an inlet cone may be quite higher than when it is absent. A major technological challenge in the regeneration of the ceramic cordierite filter is that a sudden decrease of the engine load, referred to as Drop to Idle (DTI), may create a transient temperature peak much higher than under either the initial or final stationary feed conditions. This excessive transient temperature rise may cause local melting or cracking of the ceramic filter. Suggestions on how to limit the peak temperature rise following a DTI are provided through numerous simulations of the 1-D and 2-D DPF regeneration models.
Author: Ian Patrick Tracy Publisher: ISBN: Category : Languages : en Pages : 226
Book Description
The diesel particulate filter (DPF) is a ~$5,000-$50,000 USD critical component of aftertreatment systems installed in diesel engine-powered vehicles. The device is designed to trap particles emitted by the diesel combustion process in order to prevent their release into the surrounding environment, thereby reducing pollution levels and mitigating greenhouse gas emissions. Increasing stringency of emissions regulations has progressively necessitated the installation of DPFs on diesel-powered vehicles over the past few years, with the DPF market expected to remain significant in size at least through 2025. While DPFs nominally operate by trapping and accumulating incoming PM continuously in the far downstream plug region of the filter channels so that no gaps form between trapped particulate matter (PM) agglomerates, both real-world field and laboratory bench tests have demonstrated that channel-spanning ash agglomerates form well upstream of the end plug region, prematurely clogging the mid-channel region. This effectively renders useless the remaining open space in the channel downstream of the blockage location. In addition to mid-channel congestion, this adverse phenomenon is referred to in the literature interchangeably as mid-channel collapse (MCC), mid-channel clogging, and mid-channel deposits (MCD). MCC, due to accelerated filling of the filter channels, often results in significantly reduced DPF lifetime and performance (i.e. increased backpressure yielding depressed fuel economy), both of which prove costly for diesel vehicle operators. Existing hypotheses regarding causality of MCC are largely based on inconclusive empirical observations, and not substantiated by fundamental quantitative analysis. The primary contributions of this dissertation include: 1) summarizing hypothesized causal mechanisms of MCC with an emphasis on sintering as a primary driver thereof, 2) introducing a method by which to analyze X-Ray CT scans that show MCC in DPF channels, 3) assessing the performance penalty associated with MCC by correspondingly extending the industry standard model for pressure drop across a DPF, and 4) suggesting modifications to the DPF regeneration process in order to prevent sintering of ash agglomerates to the DPF side walls, based on an efficient reformulation of the prevalent temperature history model of the DPF that solves for both flow and temperature conditions inside filter channels over time during active regeneration.
Author: Sean Andrew Munnis Publisher: ISBN: Category : Languages : en Pages : 165
Book Description
Diesel particulate filters (DPF) have seen widespread use in recent years in both on- and offroad applications as an effective means for meeting the increasingly stringent particulate emission regulations. Overtime, engine-out particulate matter composed of soot and incombustible ash accumulate within the DPF. Although soot can be removed by oxidation, ash remains within the filter and substantially accumulates over time leading to increased flow restriction thus a pressure drop across the filter. An increased pressure drop negatively affects the engine performance & fuel economy leading to the need for filter removal and cleaning. The adverse effects of ash accumulation on DPF performance have been extensively studied in the past and are well know yet the underlying mechanisms for their presence are still not well understood. The ash which accumulates within a DPF is a product of a number of factors including engine wear and corrosion as well as trace metals in diesel fuel, but the majority of the engine out ash is derived from specific metallic additives placed within the diesel lubricant. This work examines the properties of ash derived from specific single lubricant additives, as well as simple combinations, and their adverse effect on DPF performance. Specific ash properties are examined such as porosity, permeability, deposit thicknesses and packing densities along the filter channel walls as a cake layer as well as the resultant end plugs in the rear of the filter channels. Through a combined approach of experiments and theoretical models, the link between the material properties and characteristics of ash derived from single additives as well as combinations can be made to their respective impact on DPF performance. The results of this research are among a few of its kind and aim to help optimize the design of advanced diesel aftertreatment systems as well as lubricant formulations to satisfy the additive requirements for engine protection while mitigating the negative effects on DPF performance.
Author: Paul John Folino Publisher: ISBN: Category : Languages : en Pages : 115
Book Description
In order to comply with strict air emissions regulations, applicable diesel engines are required to have an installed after-treatment device. A diesel particulate filter (DPF) is one of these aftertreatment devices, and it is used to capture hazardous particulate matter (PM) from the engine exhaust stream. Over the lifetime of the DPF, incombustible materials like ash are deposited within the DPF. The presence of ash inhibits the exhaust flow and thus causes flow restriction throughout the filter. This increase in the flow restriction due to ash accumulation has an adverse effect on engine performance, primarily a reduction in fuel economy. While the global effects of ash on engine performance are well researched and understood, the fundamental mechanisms of ash phenomenology in the DPF require further understanding. Current experimental data mainly addresses how ash porosity and permeability influence pressure drop across the filter, but an investigation of these properties reveals how other key sub parameters, such as ash particle size and distribution and filter oxidation level, significantly contribute to an increase in pressure drop as well. The focus of this work is to understand the behavior of ash particles in a sintered metal fiber (SMF) filter substrate and recognize the resultant effect on DPF pressure drop using an advanced diagnostic approach. Much of the work relies on the use of sophisticated imaging and software tools to quantify properties such as particle size, particle distribution, filter porosity, and permeability among others. Additionally, this research introduces and demonstrates the capabilities of these cutting-edge tools and how they can best be utilized to provide filter performance data to qualify existing and future experimental data for SMF or cordierite filters. An analysis of the data reveals a statistically significant dependence between pressure drop and the aforementioned sub-parameters.
Author: Publisher: ISBN: Category : Languages : en Pages : 226
Book Description
The accelerated ash loading of diesel particulate filters (DPFs) by lube-oil derived products is investigated in the present study. A 517-cc single-cylinder, naturally aspirated direct-injection diesel engine is used to accelerate ash formation by artificially increasing the rate of lube-oil consumption to approximately 40 times that observed during normal engine operation. Lube-oil consumption (LOC) is accelerated by blending diesel fuel with 5% by volume of standard 15-w40 lube oil and is subsequently injected through the fuel injector into the combustion chamber. The ash loading protocol is a backpressure-based method of determining the amount of soot present within the DPF and initiating active regeneration upon achieving the target soot loading of 3 grams per liter. The final protocol employed a backpressure threshold that is defined for each individual loading by adding 0.20 psi to the baseline backpressure observed for that cycle, and consistently achieved the target soot loading. The active regeneration strategy was also refined to gradually increasing DPF temperatures to approximately 700°C. A total of five full experiments are carried out in the present investigation. Two cordierite substrates, one silicon carbide substrate, and two mullite substrates are utilized to evaluate the performance of the accelerated ash loading protocol and make necessary refinements. The rate of backpressure increase with respect to ash accumulation varies substantially between substrates. Soot lightoff temperatures for all substrates are observed to be approximately 600°C, with ash having a minimal effect on this value except in the highly-catalyzed substrates, where lightoff temperatures are initially lower but increase as ash accumulation limits exposure of the PGM to the soot layer. Characterization techniques such as Electron Probe Microanalysis (EPMA), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS), X-ray Diffraction (XRD), and Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) are used to analyze the ash layer for comparison to previously published results. All characterization results depict an ash layer that increases in thickness along the direction of flow within the DPF. The relative thickness of each ash layer is observed to be a strong function of the channel wall topography as well as the presence of catalyst and washcoat material.
Author: Yujun Wang (Ph. D.)
Author: Michael James Bahr (Nav. E.)
Author: Timothy V Johnson
Author: Gregory James Monahan
Author: Ryan Michael Morrow
Author: Mengting Yu
Author: Ian Patrick Tracy
Author: Sean Andrew Munnis
Author: Paul John Folino
Author: