Electrically Heated Diesel Particulate Filter Regeneration
Michael J. LanceJ. E. ParksAndrew A. WereszczakRaynella M. ConnatserВ. М. ПриходькоWilliam P. PartridgeE FoxMattison K. FerberEvelyne Gonze
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The purpose of this Cooperative Research and Development Agreement (CRADA) between UT-Battelle, LLC (herein referred to as the “Contractor”) and General Motors Corporation (herein referred to as “Sponsor”) is to study efficiency benefits and materials issues associated with a diesel particulate filter (DPF) device developed by the Sponsor that is regenerated electrically. The Electrically-Assisted DPF (EADPF) technology was evaluated on a GM 1.9-liter 4- cylinder diesel engine and baselined against conventional DPF regeneration strategies which utilize exothermic heating from additional fuel oxidized over an upstream diesel oxidation catalyst (DOC). In the comparison, the EADPF technology demonstrated 50% less fuel use than the conventional approach and also reduced the amount of time required for regeneration by 60%. Both benefits are dramatic improvements over the conventional technique. Although the regeneration effectiveness was limited to 85-90% for the EADPF technique, post-study analysis of the DPF substrate indicated this limitation was due to heater element cross sectional area coverage which is a limitation that can be alleviated in future designs. A fiber optic probe technique for measuring the substrate temperature during regeneration via collection and analysis of blackbody radiation spectra was successfully employed to understand substrate vs. gas temperatures (as measured by thermocouples). While substrate temperatures were found to be 15-300ºC higher than the gas temperatures, the dominant parameter dictating the range of temperatures experienced by the substrate was the soot loading prior to regeneration. Thus, control of start of regeneration is a critical parameter for successful implementation. A secant elastic modulus (ESEC) in the range of 1 - 2 GPa consistently results in analytical (FEA or numerical) and experimental correlation for deformations of DPF cordierite ceramic equibiaxial flexure, sectored flexure, and o-ring flexure specimens and for three different DPF diameters. That range of ESEC is about 4-12 times lower than reported elastic modulus for cordierite ceramics sonically and dynamically measured. As a consequence of that lower elastic modulus, the actual stresses in a DPF during regeneration will be much lower than those predicted using sonically or dynamically measured elastic modulus, and simple heater patterning (of at least two zones of annular heating), probably can be successfully employed without creating sufficiently high stresses in cordierite DPFs to initiate fracture in them. Lastly, owing to the non-linearity of stress-strain response of the cordierite material in these DPFs, a strain-based failure criterion is more appropriate for design than the herein described (and DPF-community used) stress-based criterion and the DPF community would be better served to pursue that in the future.Keywords:
Thermocouple
Diesel particulate filter (DPF) is widely used to trap fine soot particles emitted from diesel engines. It can collect particles as small as submicron but it is necessary to oxidize accumulated particles by heating the filter. Temperatures of 600 degree C or higher is required to oxidize the soot but it is difficult to maintain stable reaction because this is exoergic reaction. The filter is sometimes damaged due to thermal runaway of the reaction. To address this trade-off problem, we have studied low temperature regeneration of DPF using sliding discharge, which can be generated on the surface of DPF and produces oxidative species at room temperature. Diesel soot collected by DPF was used. Simulated air consisting of N2 and O2 and not including CO2 or CO was used and CO and CO2 concentration was monitored by real time FTIR to estimate the soot oxidation. All the experiment was carried out at temperatures between 100 and 190 degree C to simulate exhaust temperature under low load. Experimental results show that soot was oxidized by generating sliding discharge on the DPF. No thermal damage of the DPF was found. Energy efficiency, denoted by the amount of oxidized soot per electric energy dissipated in the sliding discharge, increased with increasing the temperature as well as oxygen concentration in the test gas. Small amount of Ag2O supported by the DPF significantly increase the energy efficiency of soot oxidation. On the contrary, excessive amount of Ag2O resulted in energy efficiency lower than that of DPF without Ag2O probably because the sliding discharge was not generated favorably due to high conductivity resulted from metal Ag. These results suggest that sliding discharge can induce soot oxidation and that Ag2O possibly catalyzes soot oxidation.
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Methods of regeneration of diesel particulate are discussed and the operation of diesel additives in particulate regeneration is analyzed. A diesel particulate purification device is designed by using diesel additives. How factors, such as the ratio of additives to fuel, the temperature of engine exhaust and the structure of the particulate filter, influence particulate regeneration is described through an experiment. This experiment shows that this diesel particulate purification device is effective in regenerating diesel particulate.
Diesel exhaust fluid
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Diesel Particulate Filter (DPF) is regenerated in particulate matter (PM) oxidation reaction when PM was loaded. In this report, it makes a study regarding basic calculation method of kinetics parameters using the oxidation reaction process of PM that was simulated by laboratory experiments with synthetic gases. Additionally, it reports on the results of examining the relation between temperature and time when a DPF is regenerating, using kinetic parameters.ディーゼルエンジンから排出される粒子状物質はＤＰＦで捕集後に酸化除去される。本件では、粒子状物質の酸化反応過程をモデルガス試験で再現し、酸化に関わる速度論パラメータの導出方法について基礎的な検討を行った。さらに、導出したパラメータからＤＰＦ再生時の温度と時間の関係についても検討した結果を報告する。
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Diesel Particulate Filter (DPF) is one of the prominent after-treatment devices invented to reduce particulate matter (PM) emission from diesel engines. With the latest emission standard becoming more stringent in order to maintain the environment sustainability, the study on soot filtration phenomenon occurring inside the DPF is crucial. In addition, the advancement of computer technology contributes to better understanding by simulating the soot filtration process. The flow pattern and velocity of exhaust gas are analyzed in order to examine the flow path and thus the area for soot deposition inside the channel. After a certain soot deposition time, a pressure drop is created and different patterns are observed during initial stage, soot loading and regeneration steps. The soot cake formation also affects the efficiency and pressure drop of the DPF. Hence, these understanding can be adopted for advanced research in optimizing the DPF design and efficiency.
Filtration (mathematics)
Deposition
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A major concern in operating a diesel engine is how to reduce the soot emission from the exhaust gases, as soot has a negative effect on both human health and the environment. More stringent emission regulations make the diesel particulate filter (DPF) an indispensable after-treatment component to reduce diesel soot from exhaust gases. The most important issue in developing an effective DPF, however, is regeneration technology to oxidize the diesel soot trapped in the filter, either periodically or continuously, during regular engine operations. Various methods exist for regenerating diesel soot captured by the filter. Of these, NO2 is widely used for continuous regeneration of diesel soot since it can oxidize diesel soot at lower temperatures than the conventional oxidizer O2 In this work, after introducing governing equations for trapping and regenerating diesel soot in the DPF, regeneration behavior is examined by changing such various parameters as exhaust gas temperature and O2 concentration. Numerical investigation is then performed in order to find the optimum NO2/soot ratio required for continuous regeneration of the soot deposited in the DPF.
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Reactivity
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Recently, a novel diesel particulate filter with catalyst coating draws much attention as its great performance of reducing diesel soot. In this paper, we established a mathematical model to predict and describe the pressure drop of DPF, soot loading and regeneration process. The results shows that: the model could effectively reveal the soot mass change in DPF; high flow rate causes high pressure drop in DPF and more frequent regeneration; oxygen concentration in exhaust flow affects the regeneration reaction. When the oxygen concentration equals 10%, the reaction rate and regeneration efficiency reaches highest.
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Abstract A new reactor designed to test soot combustion on a filter coated with an oxidation catalyst is described. It is designed to achieve screening investigations of catalysts in realistic conditions, i.e., close to those prevailing in a diesel particulate filter (DPF). In a DPF a soot layer is formed at the surface of a porous wall (filtration area) which may or may not be covered with a catalytic layer. In this new setup, the soot is deposited on a sample of a DPF which can be easily impregnated with oxidation catalysts. A model soot (commercial carbon black) is used for the investigation, and different procedures for the soot „deposit on the filter are tested.
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