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A Fundamental study on the effects of Electrically Heated Catalyst on State of Charge of the battery pack for a series hybrid electric vehicle at cold start.

NE Chemcat Corp-Makoto Nagata
Waseda Univ-Suchitra Sivakumar, Xieyang Yan, Hajime Shingyouchi, Toshinori Okajima, Kyohei Yamaguchi, Jin Kusaka
  • Technical Paper
  • 2020-01-0444
To be published on 2020-04-14 by SAE International in United States
Battery models are recently being developed as one of a component of the powertrain system of Hybrid Electric Vehicle (HEV) to predict the State of Charge (SOC) accurately. The electric components like the Electrically Heated Catalyst (EHC) which is used to reach the catalyst light off temperature in advance are being employed in the powertrain of HEVs. The EHC draws power from the battery pack of the HEV. Therefore, sufficient energy should be stored in the battery pack of an HEV to power the auxiliary components in the powertrain. In a series hybrid electric vehicle system, the engine is primarily used to charge the battery pack. Therefore, it is important to develop a control strategy that triggers the engine start/stop conditions and reduces the frequency of engine operation to minimize the equivalent fuel consumption. A battery pack model was constructed in MATLAB-Simulink to investigate the SOC variation of a high-power lithium ion battery during extreme engine cold start conditions (-7°C) with and without the application of EHC. An electrically heated catalyst (EHC) was also simulated…
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Numerical Studies on Temporal and Spatial Distribution of Equivalence Ratio in Diesel Combustion Using Large Eddy Simulation

Waseda University-Beini Zhou, Shotaro Yamada, Takayuki Adachi, Jin Kusaka
  • Technical Paper
  • 2019-32-0599
Published 2020-01-24 by Society of Automotive Engineers of Japan in Japan
To identify ways of achieving good mixture formation and heat release in diesel spray combustion, we have performed Large Eddy Simulation (LES) using a detailed chemical reaction mechanism to study the temporal and spatial distribution of the local equivalence ratios and heat release rate. Here we characterize the effect of the fuel injection rate profile on these processes in the combustion chamber of a diesel engine. Two injection rate profiles are considered: a standard (STD) profile, which is a typical modern common rail injection profile, and the inverse delta (IVD) profile, which has the potential to suppress rich mixture formation in the spray tip region. Experimental data indicate that the formation of such mixtures may extend the duration of the late combustion period and thus reduce thermal efficiency. Analyses of the heat release per unit fuel mass and unit entrained O2 mass under the two injection regimes indicate that IVD injection reduces the density of the fuel-air mixture in the spray tip region, increases the leanness of the spray core region, and enhances O2 entrainment,…
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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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Modeling Three-Way Catalyst Converters During Cold Starts And Potential Improvements

AZAPA Co. LTD-Katunori Umezawa, Yasuhiro Kondo
Waseda University-Xieyang Yan, Ryota Sone, Ryoya Inoue, Jin Kusaka
  • Technical Paper
  • 2019-01-2326
Published 2019-12-19 by SAE International in United States
Three-way catalyst (TWC) converters are often used to purify toxic substances contained in exhaust emissions from gasoline engines. However, a large amount of CO, NOx and THC may be emitted before the TWC reaches its light-off temperature during a cold start. In this work, a numerical model was developed for studying the purification performance of a close-coupled TWC converter during the cold start period. The TWC model was built using axisuite, commercial software by Exothermia S.A. Model gas experiments were designed for calibrating the chemical reaction scheme and corresponding reaction rate parameters in the TWC model. The TWC model was able to simulate the purification performance of CO, NOx and THC under both lean and rich air-fuel equivalence ratios (λ) for different conditions. The light-off temperature and oxygen storage capacity (OSC) behavior were also successfully validated in the model. Vehicle tests were conducted on a chassis dynamometer to verify the TWC model. The simulation achieved good agreement with the experimental data during a cold start. Based on the validated model, a parametric analysis was conducted…
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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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Exhaust Purification Performance Enhancement by Early Activation of Three Way Catalysts for Gasoline Engines Used in Hybrid Electric Vehicles

NE Chemcat Corporation-Makoto Nagata
Waseda Univesity-Toshinori Okajima, Ryota Sone, Xieyang Yan, Ryoya Inoue, Suchitra Sivakumar, Hajime Shingyouchi, Jin Kusaka, Kyohei Yamaguchi
Published 2019-09-09 by SAE International in United States
Three-way catalyst (TWC) converters are used to remove harmful substances (e.g., carbon monoxide (CO), nitrogen oxides (NOx), and hydrocarbons (HC)) emitted from gasoline engines. However, a large amount of emissions could be emitted before the TWC reaches its light-off temperature during a cold start. For hybrid electric vehicles (HEVs) powered by gasoline engines, the emission purification performance by TWC converters unfortunately deteriorates because of mode switching from engine to battery and vice versa, which can repeatedly generate cold start conditions for the TWCs. In this study, aiming to reduce emissions from series HEVs by early activation of TWCs, numerical simulations and experiments are carried out. An HEV is tested on a chassis dynamometer in the Worldwide Light-duty Test Cycle (WLTC) mode. The upstream and downstream gas conditions of the close-coupled catalyst converter are measured. A test piece is taken from the same catalyst and used in model gas experiments to decide the chemical reaction scheme and each corresponding reaction rate parameter. A 1-D numerical simulation TWC model, which includes 13 chemical species with 22 global…
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A Fundamental Study on Combustion Characteristics in a Pre-Chamber Type Lean Burn Natural Gas Engine

Waseda University-Masashi Tanamura, Shintaro Nakai, Mahoko Nakatsuka, Shota Taki, Kohei Ozawa, Beini Zhou, Ratnak Sok, Yasuhiro Daisho, Jin Kusaka
Published 2019-09-09 by SAE International in United States
Pre-chamber spark ignition technology can stabilize combustion and improve thermal efficiency of lean burn natural gas engines. During compression stroke, a homogeneous lean mixture is introduced into pre-chamber, which separates spark plug electrodes from turbulent flow field. After the pre-chamber mixture is ignited, the burnt jet gas is discharged through multi-hole nozzles which promotes combustion of the lean mixture in the main chamber due to turbulence caused by high speed jet and multi-points ignition. However, details mechanism in the process has not been elucidated.To design the pre-chamber geometry and to achieve stable combustion under the lean condition for such engines, it is important to understand the fundamental aspects of the combustion process. In this study, a high-speed video camera with a 306 nm band-pass filer and an image intensifier is used to visualize OH* self-luminosity in rapid compression-expansion machine experiment. The results show that the OH* self-luminosity is observed in outer edge of the jet, while the luminosity in the jet temporarily weakens because the turbulent jet is exposed to low temperature surrounding in the…
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A Study on Combustion Characteristics of a High Compression Ratio SI Engine with High Pressure Gasoline Injection

Mazda Motor Corp-Takashi Youso, Tatsuya Fujikawa, Masahisa Yamakawa
Waseda Univ-Takashi Kaminaga, Kyohei Yamaguchi, Sok Ratnak, Jin Kusaka
Published 2019-09-09 by SAE International in United States
In order to improve thermal efficiency of spark ignition (SI) engines, an improved technology to avoid irregular combustion under high load conditions of high compression ratio SI engines is required. In this study, the authors focused on high pressure gasoline direct injection in a high compression ratio SI engine, which its rapid air-fuel mixture formation, turbulence, and flame speed, are enhanced by high-speed fuel spray jet. Effects of fuel injection pressure, injection and spark ignition timing on combustion characteristics were experimentally and numerically investigated. It was found that the heat release rate was drastically increased by raising the fuel injection pressure. The numerical simulation results show that the high pressure gasoline direct injection enhanced small-scale turbulent intensity and fuel evaporation, simultaneously. These two effects were considered as the main factors to increase the flame propagation speed, suggesting a new combustion concept different from conventional SI combustion controlled by in-cylinder bulk flow. This combustion method enables the delay of fuel injection and spark ignition timing up to near top dead center (TDC) which leads to avoid…
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0D/1D Turbulent Combustion Model Assessment from an Ultra-Lean Spark Ignition Engine

Waseda University-Ratnak Sok, Kyohei Yamaguchi, Jin Kusaka
Published 2019-03-25 by SAE International in United States
This paper focuses on an assessment of predictive combustion model using a 0D/1D simulation tool under high load, different excess air ratio λ , and different combustion stabilities (based on coefficient of variation of indicated mean effective pressure COVimep). To consider that, crank angle resolved data of experimental pressure of 500 cycles are recorded under engine speed 1000 RPM and 2000 RPM, wide-open throttle, and λ=1.0, 1.42, 1.7, and 2.0. Firstly, model calibration is conducted using 18 cases at 2000 RPM using 500 cycle-averaged in-cylinder pressure to find optimized model constants. Then, the model constants are unchanged for other cases. Next, different cycle-averaged pressure data are used as inputs in the simulation based on the COVimep for studying sensitivity of the turbulent model constants.The simulation is conducted using 1D simulation software GT-Power. Firstly, a three-pressure analysis (TPA) model (intake, in-cylinder, exhaust) for experimental prediction and optimization of burn rate shape are studied. Boundary conditions such as the three pressure histories, intake/exhaust valves timings, boundary temperatures, and exhaust gas emissions are used as model inputs. Errors of…
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Kinetic Modeling of Ammonia-SCR and Experimental Studies over Monolithic Cu-ZSM-5 Catalyst

Hokkaido University-Wataru Eijima, Gen Shibata, Yoshimitsu Kobashi, Ryutaro Koiwai, Hideyuki Ogawa, Kenichi Shimizu
Waseda University-Jin Kusaka
Published 2019-01-15 by SAE International in United States
Ammonia-selective catalytic reduction (SCR) systems have been introduced commercially in diesel vehicles, however catalyst systems with higher conversion efficiency and better control characteristics are required to know the actual emissions during operation and the emissions in random test cycles. Computational fluid dynamics (CFD) is an effective approach when applied to SCR catalyst development, and many models have been proposed, but these models need experimental verification and are limited in the situations they apply to. Further, taking account of redox cycle is important to have better accuracy in transient operation, however there are few models considering the cycle. Model development considering the redox reactions in a zeolite catalyst, Cu-ZSM-5, is the object of the research here, and the effects of exhaust gas composition on the SCR reaction and NH3 oxidation at high temperatures are investigated. The simulations are compared with the experimental results of a surrogate gas, a mixture of nitrogen monoxide (NO), oxygen (O2), water vapor (H2O), and nitrogen (N2), and the accuracy of the developed model is validated. To investigate the effects of O2…
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