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Study for ignition characteristics and potential of gasoline autoignition combustion with spark assist

Hokkaido University-Yoshimitsu Kobashi
Kanazawa Institute of Technology-Kaname Naganuma, Koki Tanaka, Tsubasa Ito
  • Technical Paper
  • 2019-01-2317
Published 2019-12-19 by SAE International in United States
A spark assist system was installed in a gasoline direct-injection single-cylinder test engine with the aim of controlling the ignition timing and accomplishing combustion of gasoline fuel by auto/compression ignition. A primary reference fuel having an octane number of 90 (PRF 90) was used to evaluate experimentally the spark assist function for gasoline auto/compression ignition and to examine the feasibility of combustion with a short ignition delay equivalent to conventional diesel combustion using the engine system. An optically accessible single-cylinder test engine was also used to evaluate and investigate spark-assisted auto/compression ignition. Ignition timing controllability with combinations of spark and injection timings for gasoline auto/compression ignition was also investigated under different operating load conditions. The results showed that the spark assist system was required to optimize fuel sprays and a high possibility was seen for soot-less and high thermal efficiency gasoline auto/compression ignition combustion. High thermal efficiency and low emissions performance were also obtained. Thermal efficiency and emissions performance were almost the same under the different load conditions. Maximum indicated thermal efficiency of approximately 42%…
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An Investigation of the Effects of Engine Size and Rotation Speed on Diesel Combustion based on Similarity Rules

Hokkaido University-Yoshimitsu Kobashi, Yuma Tanaka, Gen Shibata, Hideyuki Ogawa
  • Technical Paper
  • 2019-01-2181
Published 2019-12-19 by SAE International in United States
This paper presents a study on the effects of the engine size and rotation speed on diesel combustion characteristics and engine performance of two differently sized diesel engines (85 mm and 135 mm bores). For simplification of the evaluation, the experimental conditions were set based on the similarity rules proposed by Chikahisa. The combustion characteristics and the indicated thermal efficiencies were compared for the small and the large engines at the same engine speed. To examine the effects of the velocities of the in-cylinder gas and the fuel spray on the combustion and the thermal efficiency, the engine speed was changed in the small engine, while maintaining a non-dimensional engine speed.
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Thermal Efficiency Improvements with Split Primary Fuel Injections in Semi-Premixed Diesel Combustion with Multi-Peak Shaped Heat Release

Hokkaido University-Kazuki Inaba, Yosuke Masuko, Yanhe Zhang, Yoshimitsu Kobashi, Gen shibata, Hideyuki Ogawa
  • Technical Paper
  • 2019-01-2170
Published 2019-12-19 by SAE International in United States
To improve the combustion characteristics in semi-premixed diesel combustion, consisting in the first-stage premixed combustion of the primary fuel injection and the second-stage spray combustion of the secondary injection, the effect of splitting the primary injection was investigated in a diesel engine and analyzed with a CFD. The indicated thermal efficiency improves due to reductions in heat transfer losses to the in-cylinder wall and the combustion noise is suppressed with the split primary injections. The CFD analysis showed that the reduction in heat transfer loss with the split primary injections is due to a decrease in the combustion quantity near the combustion chamber wall.
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A Study of a Lean Homogeneous Combustion Engine System with a Fuel Reformer Cylinder

Hokkaido University-Shuntaro Ishiguro, Gen Shibata, Hideyuki Ogawa, Yoshimitsu Kobashi, Yusuke Watanabe
YANMAR Co., Ltd.-Go Asai, Yuki Tokuoka, Thomas Bayer
  • Technical Paper
  • 2019-01-2177
Published 2019-12-19 by SAE International in United States
The Dual-Fuel (DF) combustion is a promising technology for efficient, low NOx and low exhaust particulate matter (PM) engine operation. To achieve equivalent performance to a DF engine with only the use of conventional liquid fuel, this study proposes the implementation of an on-board fuel reformation process by piston compression. For concept verification, DF combustion tests with representative reformed gas components were conducted. Based on the results, the controllability of the reformed gas composition by variations in the operating conditions of the reformer cylinder were discussed.
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Thermal Efficiency Improvement and its Mechanism at Low Load Conditions in Semi-Premixed Diesel Combustion with Twin Peak Shaped Heat Release

Hokkaido University-Kazuki Inaba, Yosuke Masuko, Yanhe Zhang, Yoshimitsu Kobashi, Gen Shibata, Hideyuki Ogawa
Published 2019-04-02 by SAE International in United States
Semi-premixed diesel combustion with a twin peak shaped heat release with the two-stage fuel injection (twin combustion) has the potential to establish efficient, low emission, and low noise operation. However, with twin combustion at low loads the indicated thermal efficiencies are poorer than at medium loads due to the lower combustion efficiencies. In this report, to increase the combustion efficiencies at low loads, the thermal efficiency related parameters were investigated in a 0.55 L single cylinder diesel engine. The results show that the indicated thermal efficiency improves with increases in the intake gas temperatures at low loads. However, at the higher loads where the combustion efficiencies are somewhat higher the indicated thermal efficiencies decrease with increases in the intake gas temperatures due to increases in the cooling losses. At the low load condition below 300 kPa IMEP, the indicated thermal efficiency is higher and the combustion noise is lower in the twin combustion than in the single premixed combustion. Further, the combustion characteristics of twin and single premixed diesel combustion at low loads were analyzed…
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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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Phenomenological Modeling and Experiments to Investigate the Combined Effects of High Pressure and Multiple Injection Strategies with EGR on Combustion and Emission Characteristics of a CRDI Diesel Engine

Hokkaido University-Kazuki Inaba
Indian Institute of Technology Madras-Saurabh Sanjay Sadafale, Mayank Mittal
Published 2019-01-15 by SAE International in United States
Nowadays, due to stringent emission regulations, it is imperative to incorporate modeling efforts with experiments. This paper presents the development of a phenomenological model to investigate the effects of various in-cylinder strategies on combustion and emission characteristics of a common-rail direct-injection (CRDI) diesel engine. Experiments were conducted on a single-cylinder, supercharged engine with displacement volume of 0.55 l at different operating conditions with various combinations of injection pressure, number of injections involving single injection and multiple injections with two injection pulses, and EGR. Data obtained from experiments was also used for model validation. The model incorporated detailed phenomenological aspects of spray growth, air entrainment, droplet evaporation, wall impingement, ignition delay, premixed and mixing-controlled combustion rates, and emissions of nitrogen oxides (NOx) and diesel soot. The detailed spray configuration provided an edge to the present model in predicting engine combustion and emission characteristics accurately. Results showed that a simultaneous reduction of NOx and soot is possible with an optimized combination of EGR and dwell period between multiple injections at high injection pressure particularly for low operating…
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Chemical Reaction Processes of Fuel Reformation by Diesel Engine Piston Compression of Rich Homogeneous Air-Fuel Mixture

SAE International Journal of Engines

Hokkaido University-Yusuke Watanabe, Shuntaro Ishiguro, Gen Shibata, Hideyuki Ogawa, Yoshimitsu Kobashi
YANMAR Co., Ltd.-Go Asai
  • Journal Article
  • 2017-32-0120
Published 2017-11-15 by Society of Automotive Engineers of Japan in Japan
To extend the operational range of premixed diesel combustion, fuel reformation by piston induced compression of rich homogeneous air-fuel mixtures was conducted in this study. Reformed gas compositions and chemical processes were first simulated with the chemistry dynamics simulation, CHEMKIN Pro, by changing the intake oxygen content, intake air temperature, and compression ratio. A single cylinder diesel engine was utilized to verify the simulation results. With the simulation and experiments, the characteristics of the reformed gas with respect to the reformer cylinder operating condition were obtained. Further, the thermal decomposition and partial oxidation reaction mechanisms of the fuel in extremely low oxygen concentrations were obtained with the characteristics of the gas production at the various reaction temperatures.The main reformed products were hydrogen (H2), carbon monoxide (CO), carbon dioxide (CO2), methane (CH4), and ethylene (C2H4) and the results indicated that the reforming depends on the maximum temperature in the cylinder, however, the amount of reformed gas is lower than the values predicted by the CHEMKIN simulation.
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Application of Large Eddy Simulation to a Torque Converter to Predict its Fluid Performance

Hokkaido University-Nobuyuki Oshima
Exedy Corporation-Tomohiro Tasaka, Shinji Fujimoto, Yuya Kishi
Published 2017-03-28 by SAE International in United States
An automatic transmission torque converter is usually used as a power transmission element, which performs the function of the torque matching and the torque amplification of the engine power output. This is referred to as the fluid performance of the torque converter, which is determined by its blade shape. Therefore, it is necessary to predict the fluid performance of the torque converter at the design stage to determine the blade shape, to which computational fluid dynamics (CFD) analysis can be applied. At present, time-averaged turbulence models such as k-ε (called Reynolds-averaged Navier–Stokes—RANS—model) are often used in such CFD analysis for industrial purposes, and are not limited to torque converters because of its appropriate calculation time. However, major traditional RANS models are less reliable for applications to complex three-dimensional flows in the torque-converter than those to simple pipe, channel and boundary layer flows. Therefore, with respect to this issue, a large eddy simulation (LES), which can directly treat the unsteady phenomena of turbulence, has been applied to such complex flow fields not only for research but…
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Combustion Noise Reduction with High Thermal Efficiency by the Control of Multiple Fuel Injections in Premixed Diesel Engines

SAE International Journal of Engines

Hokkaido University-Gen Shibata, Hideyuki Ogawa, Yuki Okamoto, Yasumasa Amanuma, Yoshimitsu Kobashi
  • Journal Article
  • 2017-01-0706
Published 2017-03-28 by SAE International in United States
Premixed diesel combustion is effective for high thermal efficiency and reductions of NOx and PM emissions, but a reduction of combustion noise is necessary for medium-high load engine operation. The control of the fuel injection has become more accurate because of the technical progress of the common rail fuel injection system, and the target heat release shape, calculated by computation, can be achieved by control of EGR, boosting, fuel injection timing, and injection quantity of multiple fuel injections.In this paper, the reduction of premixed diesel combustion noise maintaining high thermal efficiency has been investigated by the control of injection timings and heating values of multiple fuel injections. There are two aspects of the combustion noise reduction by multiple fuel injections. One is the reduction of the maximum rate of pressure rise in each combustion cycle, and the other is noise reduction effects by the noise cancelling spike (NCS) combustion.The research was conducted with both engine simulations and experiments. In combustion noise simulations, the heat release history of multiple injections was approximated by Wiebe functions and…
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