scholarly journals The state-of-the-art of soot load estimation in diesel particulate filters: A review

2021 ◽  
Vol 268 ◽  
pp. 01021
Author(s):  
Fuwu Yan ◽  
Zhizhou Cai ◽  
Jie Hu

Diesel particulate filter (DPF), as part of aftertreatment system of internal combustion engine, is considered to be the only feasible way to prominently lessen particle emissions under the requirement of today’s strict regulations such as Euro Ⅵ, US Tier 3 and China Ⅵ. This paper gives a brief introduction of the mechanism and regeneration approaches of DPF, with emphasis on soot load estimation inside the filters, which plays a vital role in formulating regeneration control strategy and ensuring exhaust systemic dependability. Various methods are covered according to different principles, including differential-pressure based methods, which are mostly used nowadays, novel model-based methods and also several newfangled soot sensors, which are progressively developed to meet the increasingly stringent on-board diagnosis (OBD) requirements. The focus of future soot detection and quantitative prediction is to improve accuracy, reliability and robustness, which may necessitate consideration of soot distribution, ash effect, failure identification and fault tolerance handling.

Author(s):  
John Hedrick ◽  
Steve Fritz ◽  
Michael Jaczola ◽  
Harold Holmes

One of the California Air Resources Board’s highest priorities is to reduce NOx and PM emissions from diesel engines. To support this goal, this project evaluated two different brands of experimental diesel particulate filters (DPF’s) on a 1,500 kW GenSet Switcher locomotives to determine their efficiency at reducing PM for this application. The locomotive used for these tests was UPY2737, an NREC Model 3GS-21B Ultra Low Emissions Locomotive (ULEL) originally manufactured in 2007. This is one of 70 of this type of locomotive operating in California. These locomotives are powered by three EPA Tier 3 nonroad, 522 kW, diesel engine driven generator sets. Upon receipt, the locomotive was baseline emission tested and the results were provided to two DPF system suppliers. Experimental DPF’s provided by these suppliers were then installed and tested using only one of the three engine-gen sets. The experimental DPF provided by Supplier “A” reduced PM emissions by 92 percent from baseline switch cycle levels, or 77 percent below the US EPA Tier 4 locomotive PM emission limit. Additionally this system essentially did not change the NOX emissions and cycle weighted fuel consumption from the engine. The experimental DPF provided by Supplier “B” also showed no significant change in the switch cycle weighted fuel consumption and NOX emission and reduced the PM emissions by 88 percent, which is 63 percent below the Tier 4 locomotive PM emissions limit. Based on these successful screening test results, projects are underway to equip all three engines with production intent retrofit DPF systems on two revenue service locomotives, one for each of the two DPF suppliers.


2019 ◽  
pp. 146808741987457 ◽  
Author(s):  
Jun Zhang ◽  
Yanfei Li ◽  
Victor W Wong ◽  
Shijin Shuai ◽  
Jinzhu Qi ◽  
...  

Diesel particulate filters are indispensable for diesel engines to meet the increasingly stringent emission regulations. A large amount of ash would accumulate in the diesel particulate filter over time, which would significantly affect the diesel particulate filter performance. In this work, the lubricant-derived ash effects on diesel particulate filter pressure drop, diesel particulate filter filtration performance, diesel particulate filter temperature field during active regeneration, and diesel particulate filter downstream emissions during active regeneration were studied on an engine test bench. The test results show that the ash accumulated in the diesel particulate filter would decrease the diesel particulate filter pressure drop due to the “membrane effect” when the diesel particulate filter ash loading is lower than about 10 g/L, beyond which the diesel particulate filter pressure drop would be increased due to the reduction of diesel particulate filter effective volume. The ash loaded in the diesel particulate filter could significantly improve the diesel particulate filter filtration efficiency because it would fill the pores of diesel particulate filter wall. The diesel particulate filter peak temperature during active regeneration is consistent with the diesel particulate filter initial actual soot loading density prior to regeneration at various diesel particulate filter ash loading levels, while the diesel particulate filter maximum temperature gradient would increase with the diesel particulate filter ash loading increase, whether the diesel particulate filter is regenerated at the same soot loading level or the same diesel particulate filter pressure drop level. The ash accumulation in the diesel particulate filter shows little effects on diesel particulate filter downstream CO, total hydrocarbons, N2O emissions, and NO2/NO x ratio during active regeneration. However, a small amount of SO2 emissions was observed when the diesel particulate filter ash loading is higher than 10 g/L. The ash accumulated in the diesel particulate filter would increase the diesel particulate filter downstream sub-23 nm particle emissions but decrease larger particle emissions during active regeneration.


2019 ◽  
Vol 9 (24) ◽  
pp. 5384 ◽  
Author(s):  
José Ramón Serrano ◽  
Pedro Piqueras ◽  
Joaquín de la Morena ◽  
Enrique José Sanchis

Late fuel post-injections are the most usual strategy to reach high exhaust temperature for the active regeneration of diesel particulate filters. However, it is important to optimise these strategies in order to mitigate their negative effect on the engine fuel consumption. This work aims at understanding the influence of the post-injection parameters, such as its start of injection and its fuel quantity, on the duration of the regeneration event and the fuel consumption along it. For this purpose, a set of computational models are employed to figure out in a holistic way the involved phenomena in the interaction between the engine and the exhaust gas aftertreatment system. Firstly, an engine model is implemented to evaluate the effect of the late fuel post-injection pattern on the gas properties at the exhaust aftertreatment system inlet in different steady-state operating conditions. These are selected to provide representative boundary conditions of the exhaust gas flow concerning dwell time, exhaust temperature and O 2 concentration. In this way, the results are later applied to the analysis of the diesel oxidation catalyst and wall-flow particulate filter responses. The dependence of the diesel particulate filter (DPF) inlet temperature is discussed based on the efficiency of each post-injection strategy to increase the exhaust gas temperature. Next, the influence on the dynamics of the regeneration of the post-injection parameters through the change in gas temperature and O 2 concentration is finally studied distinguishing the pre-heating, maximum reactivity and late soot oxidation stages as well as the required fuel consumption to complete the regeneration process.


2019 ◽  
Vol 22 (1) ◽  
pp. 50-63
Author(s):  
Christian Zöllner ◽  
Onoufrios Haralampous ◽  
Dieter Brüggemann

Understanding the variation of soot deposit properties in diesel particulate filters is necessary for their real-life modeling and onboard control. In this study, the effect of exhaust mass flow rate and particle agglomerate size on the soot layer permeability and density was investigated experimentally and analyzed using a well-validated model. A bare and a coated diesel particulate filter were loaded at five different engine operating points, specially selected to explore these effects in a heavily used part of the diesel engine map. Particle emissions were characterized in terms of particle agglomerate size distribution and primary particle diameter, while soot layer permeability and density were estimated indirectly by fitting the model to the pressure drop recordings. To this end, an automatic calibration procedure was applied to obtain values in a consistent and repeatable manner. The results showed considerable variation in both permeability and density. Furthermore, some trends could be identified after depicting the particle characterization data and soot layer properties in contour plots. Increased permeability appeared at the engine operating point with high flow rate and large particle agglomerate size. Lower density was obtained at the operating points with large particle agglomerate diameter.


Author(s):  
Di Huang ◽  
Jason M. Keith

Abstract Particulate Matter (PM) emissions from either on-road or off-road diesel engines are subject to federal and/or state standards. Recently, Diesel Particulate Filters (DPF) have been shown to be the most efficient way to reduce the PM emissions. However, DPFs need to be regenerated periodically. In order to predict when to regenerate the DPF under real-time driving conditions, a regeneration model for the DPF is needed. In this study, a transient one-dimensional model is used to track gas and solid temperatures and the particulate deposit thickness, and is studied under the Urban Dynamometer Driving Schedule (UDDS) which has variable exhaust flow rate, exhaust temperature, and PM concentration. In order to determine the best conditions, the thermal regeneration is initiated at different time points during the UDDS cycle. Moreover, we also calculate the transient temperature profile and the deposit thickness for each case. We found that the regeneration efficiency is the highest when the regeneration is initiated at 180 seconds into the UDDS cycle which corresponds to a period of extended city driving without stopping.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yun-hua Zhang ◽  
Di-ming Lou ◽  
Pi-qiang Tan ◽  
Zhi-yuan Hu

AbstractCatalyzed diesel particulate filters (CDPFs) have been widespread used as a technically and economically feasible mean for meeting increasingly stringent emissions limits. An important issue affecting the performance of a CDPF is its aging with using time. In this paper, the effects of noble metal loadings, regions and using mileage on the aging performance of a CDPF were investigated by methods of X-ray diffraction (XRD), X-ray photoelectron spectroscopy and catalytic activity evaluation. Results showed that aging of the CDPF shifted the XRD characteristic diffraction peaks towards larger angles and increased the crystallinity, showing a slowing downward trend with the increase of the noble metal loadings. In addition, the increase of the noble metal loading would slow down the decline of Pt and Pt4+ concentration caused by aging. The characteristic temperatures of CO, C3H8 conversion and NO2 production increased after aging, and the more the noble metal loadings, the higher the range of the increase. But noticeably, excessive amounts of noble metals would not present the corresponding anti-aging properties. Specifically, the degree of aging in the inlet region was the deepest, the following is the outlet region, and the middle region was the smallest, which were also reflected in the increase range of crystallinity, characteristic temperatures of CO, C3H8 conversion and NO2 production, as well as the decrease range of Pt and Pt4+ concentrations. The increase of aging mileage reduced the size of the aggregates of the soot and ash in CDPFs, however, improved the degree of tightness between particles. Meanwhile Carbon (C) concentration in the soot and ash increased with the aging mileage.


2004 ◽  
Vol 19 (10) ◽  
pp. 2913-2921 ◽  
Author(s):  
D. O’Sullivan ◽  
M.J. Pomeroy ◽  
S. Hampshire ◽  
M.J. Murtagh

A series of experiments were conducted to investigate chemical interactions between silicon carbide (SiC) and synthetic ash compositions expected to be deposited on the surfaces and within the pore structure of a diesel particulate filter. The chosen ash compositions simulated those arising from lubricants and three fuel types: standard diesel, diesel containing ferrocene as a catalytic additive, and diesel containing a cerium-based catalyst. Results demonstrated that SiC suffered little chemical or oxidative degradation in the presence of the ashes at 900 °C. For the ash not containing Fe or Ce, ash sintering effects were a possible mechanism causing filter blockage at temperatures above 970 °C. For ashes containing Fe or Ce, appreciable sintering effects were not observed below 1100 °C. Based upon the work conducted the suitability of SiC as a construction material for diesel particulate filters is not compromised by chemical degradation in the presence of lubricant/additive derived ash at temperatures less than 1100 °C.


Author(s):  
Alexander Sappok ◽  
Victor W. Wong

Diesel particulate filters (DPFs) have seen widespread use in on- and off-road applications as an effective means for meeting increasingly stringent particle emission regulations. Over time, incombustible material or ash, primarily derived from metallic additives in the engine lubricant, accumulates in the DPF. Ash accumulation leads to increased flow restriction and an associated increase in pressure-drop across the particulate filter, negatively impacting engine performance and fuel economy and eventually requiring periodic filter service or replacement. While the adverse effects of ash accumulation on DPF performance are well known, the underlying mechanisms controlling these effects are not. The results of this work show ash accumulation and distribution in the DPF as a dynamic process with each stage of ash accumulation altering the filter’s pressure-drop response. Through a combined approach employing targeted experiments and comparison with the existing knowledge base, this work further demonstrates the significant effect ash deposits have on DPF pressure-drop sensitivity to soot accumulation. Ash deposits reduce the available filtration area, resulting in locally elevated soot loads and higher exhaust gas velocities through the filter, altering the conditions under which the soot is deposited and ultimately controlling the filter’s pressure-drop characteristics. In this study, a novel accelerated ash loading system was employed to generate the ash and load the DPFs under carefully controlled exhaust conditions. The ash loading system was coupled to the exhaust of a Cummins ISB diesel engine, allowing for accelerated ash loading and DPF performance evaluation with realistic exhaust conditions. Following DPF performance evaluation, the filters were subjected to a detailed post-mortem analysis in which key ash properties were measured and quantified. The experimental results, coupled with the ash property measurements, provide additional insight into the underlying physical mechanisms controlling ash properties, ash/soot interactions, and their effects on DPF performance.


Author(s):  
Alexander Sappok ◽  
Victor W. Wong

Diesel particulate filters (DPF) have seen widespread use in on- and off-road applications as an effective means for meeting increasingly stringent particle emissions regulations. Over time, incombustible material or ash, primarily derived from metallic additives in the engine lubricant, accumulates in the DPF. Ash accumulation leads to increased flow restriction and an associated increase in pressure drop across the particulate filter, negatively impacting engine performance and fuel economy, and eventually requiring periodic filter service or replacement. While the adverse effects of ash accumulation on DPF performance are well known, the underlying mechanisms controlling these effects are not. The results of this work show ash accumulation and distribution in the DPF as a dynamic process with each stage of ash accumulation altering the filter’s pressure drop response. Through a combined approach employing targeted experiments and comparison with the existing knowledge base, this work further demonstrates the significant effect ash deposits have on DPF pressure drop sensitivity to soot accumulation. Ash deposits reduce the available filtration area, resulting in locally elevated soot loads and higher exhaust gas velocities through the filter, altering the conditions under which the soot is deposited and ultimately control the filter’s pressure drop characteristics. In this study, a novel accelerated ash loading system was employed to generate the ash and load the DPFs under carefully-controlled exhaust conditions. The ash loading system was coupled to the exhaust of a Cummins ISB diesel engine, allowing for accelerated ash loading and DPF performance evaluation with realistic exhaust conditions. Following DPF performance evaluation, the filters were subjected to a detailed post-mortem analysis in which key ash properties were measured and quantified. The experimental results, coupled with the ash property measurements, provide additional insight into the underlying physical mechanisms controlling ash properties, ash/soot interactions, and their effects on DPF performance.


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