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Diesel Emissions and Approaches to their Mitigation
Published in Ozcan Konur, Petrodiesel Fuels, 2021
I. M. Rizwanul Fattah, Hwai Chyuan Ong, T. M. Indra Mahlia, M. Mofijur
‘Diesel particulate filter’ (DPF) is a type of monolithic filter which is used to trap particles of micron and sub-micron sizes carried by the exhaust gases (Salvat et al., 2000). The most commonly used one is wall-flow DPF which has the cells alternately plugged at each end where the exhaust gas permeates through the walls of the filter while the particles are trapped. Due to the continuous use of DPF, there is a chance of clogging, which requires periodic regeneration to oxidize the accumulated soot in the filter and keep its pressure drop at a reasonable level to ensure fuel economy and the proper working of the engine. In general, DPF should possess high filtration efficiency, less pressure drop, high soot-storing capacity, compatibility, and stability (mechanical, thermal, and chemical) with regeneration methods.
Fuels and combustion & emissions
Published in Allan Bonnick, Automotive Science and Mathematics, 2008
Particulate matter that arises from combustion in diesel engines consists mainly of particles of carbon with some absorbed hydrocarbons. Filtration of the exhaust products is a technique that is widely used for the removal of particulate matter from exhaust gases before they are passed into the atmosphere. Various forms of filtering medium are used to trap the PM and, in common with most filtering processes, cleaning of the filter to avoid blockage is required. The cleaning process in diesel particulate filters (DPFs), which consists primarily of controlled burning to convert the carbon (soot) into carbon dioxide, is known as regeneration. Among the methods of regeneration are: Passive systems The heat in the exhaust gas, acting with the materials used in the construction of the particulate filter, produces sufficient temperature to remove the filtered deposits. External sources of heat are not required.Active systems Heat is supplied either by injecting fuel into the exhaust stream, or by secondary injection of fuel into the engine; this creates the temperature that is required to burn off the particulate matter that accumulates in the filter.
Off-Road and Heavy Equipment Lubricants and Lubrication
Published in Leslie R. Rudnick, Synthetics, Mineral Oils, and Bio-Based Lubricants, 2020
A combination of the following devices represents the most commonly used emissions reduction strategies in heavy-duty diesel engines: Diesel particulate filters (DPF): reduce soot and particulate matter from exhaust gas. Typically, DPF is a ceramic matrix – with or without a catalyst – that filters out soot and particulates. During engine operation, the DPF is heated per a predetermined timing strategy to high temperatures to convert soot into carbon dioxide. Any ash-forming components in the soot, mostly from fuel sulfur and oil additives, leave ash residue on the DPF surfaces. When the ash accumulation reaches certain predetermined levels the DPF has to be serviced. A minimum service time is mandated by regulatory agencies.Diesel oxidation catalyst (DOC): oxidizes carbon monoxide and gas phase hydrocarbons to CO2 and H2O. DOC uses palladium, platinum, and/or aluminum oxides to catalytically oxidize CO and hydrocarbons in the presence of oxygen available in the exhaust gas. Sulfur, phosphorus, and some metals used in oil additives or which are part of the base stocks can coat the active surfaces of the DOC and reduce its effectiveness.Selective catalytic reduction (SCR): reduces NOx emissions from exhaust gas. SCR works by using urea to convert NOx in exhaust gas into benign N2 gas. SCR is less sensitive than other devices to oil additives, but benefits from overall reduction of metals, sulfur, and phosphorus from the oil and fuel.
Numerical simulation of DPF thermal regeneration process based on an improved dynamic model
Published in International Journal of Green Energy, 2020
Bingxia Liu, Ping Sun, Suresh Aggarwal, Shaojun Liu, Junheng Liu
DPF is a device that uses physical methods to reduce exhaust particles. When working, it only filters and deposits the particles in the exhaust in the filter element, and cannot remove the particles (Palma et al. 2013; Yang et al. 2015; Yoon et al. 2015). As more and more particles are accumulating in the DPF, it increases the back pressure of the exhaust system, affects the ventilation process of the diesel engine, and thus affects the overall performance of the diesel engine (Jiao et al. 2017; Karavalakis et al. 2017; Mokhria et al. 2012; Xu et al. 2016). Therefore, the particles trapped in the DPF must be removed in time for the DPF to continue normal operation, which is defined as the regeneration of DPF, and represents a critical factor whether the DPF can be used normally on diesel engines (Kazuhiro and Tatsuya 2015; Liu et al. 2020; Vincenzo et al. 2015).
Accelerated ash accumulation method for diesel particulate filter and its characterization: a review
Published in International Journal of Green Energy, 2020
Zuwei Zheng, Sheng Su, Reggie Zhan, He Lin, Yinan Wang, Xuteng Zhao
Regarding that the recent China VI emissions legislation (MEEPRC 2018) is similar to EURO 6, it is widely deemed as the most stringent vehicle emission regulation so far. The emission limits of gaseous and particulate matter (PM) are getting more stringent, and particulate number (PN) limit is also set for the first time for heavy-duty diesel engines. Diesel particulate filter (DPF) technology has been proved to be the most effective technology to reduce PM and PN emissions. With the utilized of DPF on the diesel engines of model year 2007, which were totally compliant with the 2007 USD emission legislation, the PM emission from the engines were efficiently reduced by more than 99% (Eakle et al. 2018). To meet the recent emission requirement, accordingly, DPF will be mandatory for all heavy-duty diesel vehicles.
Effects of different diesel particulate filter on emission characteristics of in-use diesel vehicles
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2019
Jiachen Li, Yunshan Ge, Haohao Wang, Chao Yu, Xindi Yan, Lijun Hao, Jianwei Tan
This study extends our understanding of retrofitting heavy diesel engines in urban transportation by installing matched DPF. The relevant conclusions drawn from the test can be summarized as follows: All kinds of DPF could sharply reduce PN emission in the exhaust. After suitable matching and installation of DPF, the filtration rates of PM emission number (PN) were over 96% for all in-use diesel engines. DPF is one of the suitable technological routes that can readily make PM emissions of in-use diesel engines pass the national regulatory emission standards;As evident from the test, for heavy diesel engines which worked main at low speed and exhaust temperature, active regeneration DPF had better filtration rate. For heavy diesel engines which worked main at high speed and exhaust temperature, passive regeneration DPF had greater catching efficiency and steadier working state;According to the test, passive regeneration DPF has better filtration rate on non-road diesel engines. However, for reliability and durability consideration, non-road diesel engines should mainly be matched with active regeneration DPF.