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Analysis of NH3 Diffusion Phenomena in a Selective Catalytic Reduction Coated Diesel Particulate Filter Catalyst Using a Simple One-Dimensional Core Model

Waseda University-Ken Sahara, Yoshihisa Tsukamoto, Akihisa Ishimaru, Takao Fukuma, Jin Kusaka
  • Technical Paper
  • 2019-01-2236
Published 2019-12-19 by SAE International in United States
This paper describes a method for estimating constants related to NH3 gas diffusion phenomena to the active sites in a selective catalytic reduction diesel particulate filter (SCR/DPF) catalyst. A simple one-dimensional NH3 gas diffusion model based on the pore structure inside the catalyst was developed and used to estimate the intracrystalline diffusion coefficient. It was shown that the estimated value agreed well with experimental data.
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Analysis and Modeling of NOx Reduction Based on the Reactivity of Cu Active Sites and Brønsted Acid Sites in a Cu-Chabazite SCR Catalyst

Waseda Univ-Yoshihisa Tsukamoto, Takao Fukuma, Jin Kusaka
Published 2019-09-09 by SAE International in United States
The NOx-reducing activity of a Cu-chabazite selective catalytic reduction (SCR) catalyst was analyzed over a wide temperature range. The analysis was based on the ammonia SCR (NH3-SCR) mechanism and accounted for Cu redox chemistry and reactions at Brønsted acid sites. The reduction of NOx to N2 (De-NOx) at Cu sites was found to proceed via different paths at low and high temperatures. Consequently, the rate-limiting step of the SCR reaction at Cu sites varied with the temperature. The rate of NOx reduction at Cu sites below 200°C was determined by the rate of Cu oxidation. Conversely, the rate of NOx reduction above 300°C was determined by the rate of NH3 adsorption on Cu sites. Moreover, the redox state of the active Cu sites differed at low and high temperatures. To clarify the role of the chabazite Brønsted acid sites, experiments were also performed using a H-chabazite catalyst that lacks Cu sites. NOx reduction via the NO2-NH3 reaction was found to occur at Brønsted acid sites at high temperatures (up to 600°C). We also analyzed the…
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A Statistical Approach to Improve the Accuracy of the DPF Simulation Model under Transient Conditions

Engine Control Systems-Takao Fukuma
Waseda University-Daisuke Tsujimoto, Kusaka Jin
Published 2019-01-15 by SAE International in United States
Cars with diesel engines are commonly equipped with a Diesel Particulate Filter (DPF) to reduce their emissions of particulate matter (PM). Because the pressure drop within the DPF reduces engine performance, it must be predicted with accuracy. The purpose of this study was to improve the accuracy of a DPF simulation model under transient conditions by parameter optimization.The DPF model under consideration consists of an inlet channel, a cake layer, wall layer, and an outlet channel. The pressure drop is influenced by the location, mass, and density of the deposited soot. Therefore, the model includes the following sub-models:Sub-model 1: Calculates the soot density deposited in the wall layerSub-model 2: Computes the filtration efficiency and mass of the wall and cake layerSub-model 3: Calculates the soot density deposited in the cake layerBecause the sub-models include some empirical formulae, the first step in refining the model was to optimize their fitting parameters.Two sets of experiments were conducted: soot loading experiments under steady-state conditions for parameter optimization, and soot loading experiments under transient conditions for model validation.Therefore, the…
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Effects of Soot Deposition on NOx Purification Reaction and Mass Transfer in a SCR/DPF Catalyst

Waseda University-Yoshihisa Tsukamoto, Shun Utaki, Wencong Zhang, Takao Fukuma, Jin Kusaka
Published 2018-09-10 by SAE International in United States
Experimental studies were carried out to investigate the effect of soot deposition on NOx purification phenomena in an ammonia selective catalytic reduction coated diesel particulate filter (SCR/DPF) catalyst. To study soot deposition effects on the chemical reactions and mass transfer, two types of testing device were used. A synthetic gas bench enabling tests to be conducted with temperature and flow rate ranges relevant to real driving conditions was used to investigate the soot influence on reduction of NOx to N2 (DeNOx). A micro-reactor that removed the effect of soot deposition on mass transfer in the catalyst layer was used to analyze chemical reactions on a soot surface and their interaction with the SCR catalyst. A filter test brick of a Cu-zeolite SCR/DPF catalyst and a powder catalyst were used for the synthetic gas bench and micro-reactor tests, respectively. Engine soot was sampled in all the tests. The synthetic gas bench results showed that soot deposition had a negative impact on NOx conversion performance. The micro-reactor results showed that NOx purification reactions took place simultaneously with…
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A Quasi Two Dimensional Model of Transport Phenomena in Diesel Particulate Filters - The Effects of Particle Diameter on the Pressure Drop in DPF Regeneration Mode-

Waseda University-Toru Uenishi, Eijiro Tanaka, Takao Fukuma, Jin Kusaka, Yasuhiro Daisho
Published 2016-10-17 by SAE International in United States
Experimental and numerical studies on the combustion of the particulate matter in the diesel particulate filter with the particulate matter loaded under different particulate matter loading condition were carried out. It was observed that the pressure losses through diesel particulate filter loaded with particulate matter having different mean aggregate particle diameters during both particulate matter loading and combustion periods. Diesel particulate filter regeneration mode was controlled with introducing a hot gas created in Diesel Oxidation Catalyst that oxidized hydrocarbon injected by a fuel injector placed on an exhaust gas pipe. The combustion amount was calculated with using a total diesel particulate filter weight measured by the weight meter both before and after the particulate matter regeneration event. Particulate matter loaded in the larger mean aggregate particle diameter condition is oxidized slower than that in the smaller mean aggregate particle diameter condition . It is confirmed with the fact that the pressure drop through the diesel particulate filter with the particulate matter loaded in the smaller mean aggregate particle diameter condition decreased more than the larger…
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A Quasi Two Dimensional Model of Transport Phenomena in Diesel Particulate Filters - The Effects of Particle and Wall Pore Diameter on the Pressure Drop -

Waseda University-Toru Uenishi, Eijiro Tanaka, Genki Shigeno, Takao Fukuma, Jin Kusaka, Yasuhiro Daisho
Published 2015-09-01 by SAE International in United States
Experimental and numerical studies were conducted on diesel particulate filters (DPFs) under different soot loading conditions and DPF configurations. Pressure drops across DPFs with various mean pore diameters loaded with soots having different mean particle diameters were measured by introducing exhaust gases from a 2.2 liter inline four-cylinder, TCI diesel engine designed for use in passenger cars. A mechanistic hypothesis was then proposed to explain the observed trends, accounting for the effects of the soot loading regime in the wall and the soot cake layer on the pressure drop. This hypothesis was used to guide the development and validation of a numerical model for predicting the pressure drop in the DPF. The relationship between the permeability and the porosity of the wall and soot cake layer was modeled under various soot loading conditions. An equation predicting the porosity of the soot-coated wall and the soot cake layer was derived as a function of the mean diameter of secondary soot particles. The percolation coefficient at which the soot filtering regime changed from wall trapping to cake…
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Development of NSR and DiAir System to Achieve Clean Emissions under Transient Cycle

Toyota Motor Corp.-Kohei Yoshida, Yusuke Nozaki, Toshihiro Mori, Yuki Bisaiji, Yuki Haba, Kazuhiro Umemoto, Takao Fukuma
Published 2014-10-13 by SAE International in United States
In this paper, a control strategy to switch NSR (NOx storage and reduction) function from standard DeNOx by rich combustion to DiAir (Diesel NOx After-treatment by Adsorbed Intermediate Reductants) and additional advantages to use HCI (Hydrocarbon Injector) during desulfation were introduced. Investigations under a transient cycle suggest that NOx conversion with DiAir is strongly affected by preliminary NOx storage condition in the NSR catalyst. To avoid NOx breakthrough just after starting HC dosing for DiAir, a rich operation to reduce stored NOx was shown to be important and high NOx conversion could be maintained using this control strategy under a transient cycle. Furthermore, by combining HCI and in-cylinder post injection, usage of rich condition for NSR DeSOx can be expand to wider engine speed and load area. Thanks to a high NOx conversion efficiency in high temperature, including DPF(diesel particulate filter) regeneration, with DiAir, a NOx storage function in low load driving and the advantage of HCI during DeSOx, promising potential to reduce NOx emission in real driving condition was shown.
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Reaction Mechanism Analysis of Di-Air-Contributions of Hydrocarbons and Intermediates

SAE International Journal of Fuels and Lubricants

Toyota Motor Corporation-Yuki Bisaiji, Kohei Yoshida, Mikio Inoue , Nobuyuki Takagi, Takao Fukuma
  • Journal Article
  • 2012-01-1744
Published 2012-09-10 by SAE International in United States
The details of Di-Air, a new NOx reduction system using continuous short pulse injections of hydrocarbons (HC) in front of a NOx storage and reduction (NSR) catalyst, have already been reported. This paper describes further studies into the deNOx mechanism, mainly from the standpoint of the contribution of HC and intermediates.In the process of a preliminary survey regarding HC oxidation behavior at the moment of injection, it was found that HC have unique advantages as a reductant. The addition of HC lead to the reduction or metallization of platinum group metals (PGM) while keeping the overall gas atmosphere in a lean state due to adsorbed HC. This causes local O₂ inhibition and generates reductive intermediate species such as R-NCO.Therefore, the specific benefits of HC were analyzed from the viewpoints of 1) the impact on the PGM state, 2) the characterization of intermediate species, and 3) Di-Air performance compared to other reductants. As a result, the operando dispersive X-ray adsorption fine structure (DXAFS) method was used to find that HC prolong the metallic state of Pt…
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Modeling of Diesel Engine Components for Model-Based Control (Third Report)~Application of High Speed Calculation Diesel Combustion Model Into Multiple Fuel Injection and Validation of Prediction Accuracy

Yasumasa Suzuki, Jin Kusaka, Masatoshi Ogawa, Harutoshi Ogai, Shigeki Nakayama, Takao Fukuma
  • Technical Paper
  • 2011-08-0661
Published 2011-10-12 by Society of Automotive Engineers of Japan in Japan
In this study, High Speed Calculation Diesel Combustion model that was constructed for Model-Based Control was improved and examined the predictive accuracy of in-cylinder pressure, rate of heat release and NOx emission under multiple fuel injection condition. With the object of reduction in calculation load and to improve predictive accuracy, the simplified sub-model for prediction of equivalence ratio distribution and variation in cylinder and turbulence kinetic energy (TKE) and dissipation rate of TKE was installed in High Speed Diesel Combustion model. The results indicated that improved High Speed Calculation Diesel Combustion model can predict combustion and NOx emission under various engine speeds and load conditions with high accuracy and calculation time decreased nearly 50-80%.
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Modeling of Diesel Engine Components for Model-Based Control (First Report): The construction and validation of a model of the Air Intake System

Toyota Motor Corp.-Shigeki Nakayama, Takao Fukuma
Waseda Univ.-Toshitaka Nakamura, Yasumasa Suzuki, Jin Kusaka, Masatoshi Ogawa, Harutoshi Ogai
Published 2011-08-30 by SAE International in United States
Model based control design is an important method for optimizing engine operating conditions so as to simultaneously improve engines' thermal efficiency and emission profiles. Modeling of intake system that includes an intake throttle valve, an EGR valve and a variable geometry turbocharger was constructed based on conservation laws combined with maps. Calculated results were examined the predictive accuracy of fresh charge mass flow, EGR rate and boost pressure.
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