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Split Injection Spray Development, Mixture Formation, and Combustion Processes in a Diesel Engine Piston Cavity: Rig Test and Real Engine Results

Toyota Industries Corp.-Mamoru Suzuki, Tsutomu Umehara
University of Hiroshima-Tomoya Shiwaku, Shintaro Yasaki, Keiya Nishida, Youichi Ogata
Published 2018-09-10 by SAE International in United States
The objectives of this study are to investigate the effects of premixed charge compression ignition (PCCI) strategies with split injection on soot emission characteristics. The split injection conditions included three injection intervals (1.1 ms, 1.3 ms, and 1.5 ms) and three injection quantity fraction ratios (Q1/Q2 = 10.0/14.6 mm3/st, 15.2/9.4 mm3/st, and 20.0/4.6 mm3/st). The results in real engine tests showed that shorter injection intervals, and the 1st injection quantity contributes to reduced soot emissions.A rig test with high-pressure and high-temperature constant-volume vessel (CVV) and a two-dimensional (2D) model piston cavity were used to determine correlations between injection conditions and soot emissions. During the rig test, fuel was injected into the CVV by a single-hole nozzle under split injection strategies. The injection strategies include the same injection intervals and quantity fraction ratios as in the real engine test. The 2D piston cavity model took the same shape as that used in a small-bore diesel engine to investigate spray development, mixture formation, and combustion process. Tracer laser absorption scattering (LAS) was used to observe the spray…
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Numerical Assessment of Controlling the Interval between Two Heat-Release Peaks for Noise Reduction in Split-injection PCCI Combustion

Keio University-Mina Nishi, Hiroki Ikeda, Norimasa Iida
Toyota Central R&D Labs Inc.-Takayuki Fuyuto
Published 2015-09-01 by SAE International in United States
In PCCI combustion with multiple injections, the mechanism having two heat release peaks which has a favorable characteristic of reducing noise is studied using numerical tool of single- and also multi-zone model of CHEMKIN PRO. In the present investigation, the physical issues, such as variations in the equivalent ratio and temperature caused by the fuel injection are simplified first so that the key issues of chemical reaction occurred in the combustion chamber can be extracted and are discussed in detail. The results show that the interval of two heat-release peaks can be controlled and as the number of zones of the calculation increases, the change in the timing of a heat release peak is increased but over three-zones, it is not affected any more. This indicates that to study about complex diesel combustion phenomena, three-to four-zone model shall give sufficiently accurate results.
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An Investigation of Controlling Two-Peak Heat Release Rate for Combustion Noise Reduction in Split-Injection PCCI Engine using Numerical Calculation

Keio Univ-Hiroki Ikeda, Norimasa Iida
Toyota Central R&D Labs Inc-Takayuki Fuyuto
Published 2014-11-11 by SAE International in United States
A combustion method called Noise Canceling Spike (NC-Spike) Combustion [1, 2] has been reported in the co-author's previous paper, which reduces combustion noise in PCCI with split injection. This NC-Spike Combustion uses interference of the following “spike” of pressure rise on the preceding peak of pressure rise. The overall combustion noise is reduced by lowering the maximum frequency component of the noise spectrum. The period of this frequency is two times of the time interval between the two peaks of the pressure rise rate. This maximum load range of conventional PCCI combustion is limited by the combustion noise, since the maximum pressure rise rate increases as the amount of injected fuel increases. The NC-Spike Combustion has a potential to extend of the operating range of PCCI combustion. In this paper, we investigated feasibility and controllability of the two-peak heat release rate during high temperature heat release by adding fuel in the adiabatic compression process of pre-mixed gas. Numerical calculation using a multi-zone model was performed in consideration of the fuel inhomogeneity. In this paper, 2…
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Noise and Emissions Reduction by Second Injection in Diesel PCCI Combustion with Split Injection

SAE International Journal of Engines

Toyota Central R&D Labs Inc.-Takayuki Fuyuto, Masahiro Taki, Reiko Ueda, Yoshiaki Hattori
Toyota Industries Corp.-Hiroshi Kuzuyama, Tsutomu Umehara
  • Journal Article
  • 2014-01-2676
Published 2014-10-13 by SAE International in United States
An author's previous studies addressed a combustion system which reduces emissions, noise, and fuel consumption by using PCCI with the split injection of fuel. This concept relies on the premixed combustion of the first injected fuel and accelerated oxidation by the second injected fuel. Although this combustion system requires the optimization of the timing of the second injection, the details of how noise and emissions are reduced have not been elucidated.In this paper, the authors explain the mechanism whereby emissions and noise are reduced by the second injection.In-cylinder visualizations and numerical simulations both showed an increase in smoke and CO as the second injection timing was advanced, as induced by the inhibited oxidation of the rich flame. When the second injection timing is excessively retarded, the amount of soot forming around the near-nozzle increased. The second fuel injection at the optimum timing can mix with the air in the inner-region of the cavity, such that no soot is formed in the near-nozzle region.Combustion noise spectra analysis revealed that noise canceling occurs between two peaks in…
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Analysis of CO Emission Sources in Diesel Combustion (Third Report)~CO Reduction Techniques and its Validation

Toyota Central R&D Labs.-Takayuki Fuyuto, Reiko Ueda, Yoshiaki Hattori, Jun'ichi Mizuta, Kazuhiro Akihama
Toyota Industries Corp.-Hideki Aoki, Tsutomu Umehara
  • Technical Paper
  • 2012-08-0340
Published 2012-05-23 by Society of Automotive Engineers of Japan in Japan
CO emission sources from diesel combustion with multiple fuel injections were analyzed by using in-cylinder CO-LIF imaging and numerical simulation. The major source of CO emission under low-load conditions is the over-diffusion of pilot sprays, and that under high-load condition is the shortage of oxygen in the rich regions at the frame front. As an example of CO reduction techniques, a new piston-cavity with a stepped lip which reduces the squish flow velocity was introduced. Its effects on CO emission were validated by exhaust emission tests and simulations.
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High Efficiency and Clean Diesel Combustion Concept using Double Premixed Combustion: D-SPIA

Toyota Industries Corporation-Hiroshi Kuzuyama, Masahiro Machida, Tsutomu Kawae, Takeshi Tanaka, Hideki Aoki, Yoshio Sugiyama, Tsutomu Umehara
Published 2012-04-16 by SAE International in United States
A new concept, Diesel Staggered Premixed Ignition with Accelerated oxidation (D-SPIA) was developed for lower exhaust emissions and carbon dioxide (CO₂) and this is based on divided fuel injection before top dead center (TDC). D-SPIA is a result of investigating various diesel combustion methods. Although the D-SPIA is a type of Premixed Charge Compression Ignition (PCCI), it has a distinct feature of double premixed combustion by optimum injection quantities and staggered timing, which can achieve an ideal heat release rate for low pollutant emissions and fuel consumption.Based on this concept, second injection timing and the proportion of the second fuel injection quantity play significant roles to reduce smoke, and hydrocarbon (HC) and carbon monoxide (CO) emissions. The second injection timing has a close relation to the premixed time of the second fuel injection and smoke level. The in-cylinder temperature at the second injection timing, which is related to the premixed time of the second fuel injection, is affected by the low-temperature heat release (LTHR) or the high-temperature heat release (HTHR) of the first fuel injection.…
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High Efficiency and Clean Diesel Combustion Concept Using Double Premixed Combustion (Second Report)~Influence of Environmental Variation and Fuel Cetane Quality on New Concept Combustion

Tsutomu Kawae, Hiroshi Kuzuyama, Takeshi Tanaka, Hideki Aoki, Yoshio Sugiyama, Tsutomu Umehara
  • Technical Paper
  • 2011-08-0656
Published 2011-10-12 by Society of Automotive Engineers of Japan in Japan
We investigated combustion robustness of new concept combustion, named D-SPIA, regarding intake air temperature, engine coolant temperature and fuel cetane quality. Through this testing we found out that heat release rate of D-SPIA could be maintained at desired phase by control of air-fuel ratio and/or injection timing against change of the environmental conditions. Besides, the combustion of D-SPIA was stable for using of lower cetane fuel.Finally, we tested a prototype engine installed D-SPIA combustion concept on transient engine test bench and could verify it had a potential to meet Euro6 regulation without any DeNOx after-treatment, showing no fuel penalty.
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Analysis of CO Emission Sources in Diesel Combustion (Second Report)~Validation of Numerical Simulation and Analysis of CO Emission Sources

Takayuki Fuyuto, Reiko Ueda, Takafumi Matsumoto, Yoshiaki Hattori, Jun'ichi Mizuta, Kazuhiro Akihama, Hideki Aoki, Tsutomu Umehara, Hisaki Ito, Akio Kawaguchi
  • Technical Paper
  • 2011-08-0658
Published 2011-10-12 by Society of Automotive Engineers of Japan in Japan
In-cylinder CO distribution in diesel combustion was measured using two-photon excitation CO-LIF. The results obtained with CO-LIF were used to validate the accuracy of a numerical simulation. The measured location of the dense CO gas cloud, as obtained by the LIF measurement, agreed closely with the results of the simulation. The major source of the CO emissions under low-load conditions is the over-diffusion of the pilot sprays, while that under high-load conditions is the shortage of oxygen in the rich regions at the flame front.
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Analysis of CO Emission Sources in Diesel Combustion (First Report)~In-Cylinder CO Imaging Using 2-Photon Excitation LIF

Toyota Central R&D Labs.-Takayuki Fuyuto, Takafumi Matsumoto, Yoshiaki Hattori, Reiko Ueda, Kazuhiro Akihama
Toyota Industries-Hideki Aoki, Tsutomu Umehara
  • Technical Paper
  • 2011-08-0096
Published 2011-10-12 by Society of Automotive Engineers of Japan in Japan
To analyze the carbon monoxide (CO) emission sources in diesel combustion, an in-cylinder CO imaging technique using two-photon excitation LIF was developed. While overlapping of the light emitted by the soot particles, over the weak CO fluorescence, became a serious problem, it was solved by optimizing the imaging direction, and by increasing the level of laser irradiation used for LIF excitation. The results of in-cylinder CO-LIF imaging were compared with the results obtained with CFD simulation and the agreement was found to be excellent. The results of LIF and CFD showed that the major source of CO emissions under low load conditions is the over-diffusion of the pilot sprays. These prevent the local temperature from rising sufficiently to oxidize the CO.
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High Efficiency and Clean Diesel Combustion Using Double Premixed Ignition (First Report)~Development of a New Combustion Concept and Potential of Emission Reduction

Hiroshi Kuzuyama, Masahiro Machida, Tsutomu Kawae, Tsutomu Umehara
  • Technical Paper
  • 2011-08-0655
Published 2011-10-12 by Society of Automotive Engineers of Japan in Japan
It is very important and urgent subject that internal combustion engines have better combustion potential on clean and high efficiency performance for energy-saving future. We developed a new concept combustion for lower exhaust emission included CO₂, named Diesel Staggered Premixed Ignition with Accelerated Oxidation (D-SPIA), that is based on divided fuel injections before TDC. Although our D-SPIA belongs to a kind of PCCI (Premixed Charge Compression Ignition), it has a distinct feature of double premixed combustion by optimum injection quantities and staggered timing, which can achieve an ideal heat release rate for low pollutant emission and fuel consumption stably.