An Analysis on Cycle-by-cycle Variation and Trace-knock using a Turbulent Combustion Model Considering a Flame Propagation MechanismTaizo Kitada; Takayuki Shirota; Shinji Hayashi; Dai Tanaka; Masato Kuchita; Yasuyuki Sakai; Yukihide Nagano; Toshiaki Kitagawa, © 2019 SAE Japan and SAE International. Gasoline engines have the trace-knock phenomena induced by the fast combustion which happens a few times during 100 cycles. And that constrains the thermal efficiency improvement due to limiting the ignition timing advance. So the authors have been dedicating a trace-knock simulation so that we could obtain any pieces of information associated with trace-knock characteristics. This simulation consists of a turbulent combustion model, a cycle-by-cycle variation model and a chemical calculation subprogram. In the combustion model, a combustion zone is considered in order to obtain proper turbulent combustion speed through wide range of engine speed. From a cycle-by-cycle variation analysis of an actual gasoline engine, some trace-knock features were detected, and they were involved in the cycle-by-cycle variation model. And a reduced elementary reaction model of gasoline PRF (primary reference fuel) was customized to the knocking prediction, and it was used in the chemical calculation. Through the trace-knock simulation, some advantages of the cycle-by-cycle variation model and the chemical reaction calculation became obvious. In this paper, the details of these calculation methods are described, and the advantages of this calculation are discussed.
SAE Technical Papers, 2019年12月
High-Temperature Unimolecular Decomposition of Diethyl Ether: Shock-Tube and Theory Studies
Paul Sela; Yasuyuki Sakai; Hang Seok Choi; Jürgen Herzler; Mustapha Fikri; Christof Schulz; Sebastian Peukert
J. Phys. Chem. A, 2019年07月, ［査読有り］
Mechanism of Wall Turbulence Modulation With Premixed Hydrogen Combustion
Takashi Ohta; Yuta Onishi; Yasuyuki Sakai
ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference (AJKFluids2019), 2019年07月, ［査読有り］
燃焼帯を考慮した乱流燃焼モデルを使ったトレースノックの解析
北田 泰造; 城田 貴之; 野中 一成; 飯塚 捷; 田中 大; 口田 征人; 酒井 康行; 永野 幸秀; 北川 敏明
自動車技術会論文集, 2019年03月, ［査読有り］
Shock-tube study of the ignition and product formation of fuel-rich CH4/air and CH4/additive/air mixtures at high pressure
J. Herzler; Y. Sakai; M. Fikri; C. Schulz
Proc. Combust. Inst., 2019年01月, ［査読有り］
High-temperature gas-phase kinetics of the thermal decomposition of tetramethoxysilane
P. Sela; S. Peukert; J. Herzler; Y. Sakai; M. Fikri; C. Schulz
Proc. Combust. Inst., 2019年01月, ［査読有り］
飽和炭化水素の化学構造と層流燃焼速度の関係
酒井 康行; 三好 明
自動車技術会論文集, 2019年01月, ［査読有り］
燃焼の反応機構と反応素過程 – (3)反応機構簡略化
酒井 康行
日本燃焼学会誌, 2018年08月
ガソリンサロゲート詳細反応機構
三好 明; 酒井 康行
自動車技術, 2018年04月
Influence of vortical structures on ignition in DNS of a turbulent mixing layer with non-premixed H2/air combustion
Tatsuya Yonemura; Takashi Ohta; Yasuyuki Sakai
Asia-Pacific Conference on Combustion (ASPACC2017), 2017年12月, ［査読有り］
Experimental study on the effect of lubricant oil on ignition characteristics using a rapid compression machine
Yuusuke Wachi; Kazuki Iwakura; Kotaro Tanaka; Mitsuru Konno; Ying Jiang; Yasuyuki Sakai
Asia-Pacific Conference on Combustion (ASPACC2017), 2017年12月, ［査読有り］
A study on practical utilization of diesel combustion calculation - A series of studies for automatic diesel engine adaptation
Taizo Kitada; Shinji Hayashi; Masato Kuchita; KeiShigahara; Yasuyuki Sakai
COMODIA2017, 2017年07月, ［査読有り］
Empirical approach to small-scale reaction mechanism for regular gasoline surrogate fuel
Kazunari Kuwahara; Yoshihiro Ueda; Yasuyuki Sakai; Tsukasa Hori; Tomoyuki Mukayama; Eriko Matsumura; Jiro Senda
COMODIA2017, 2017年07月, ［査読有り］
Reduced chemical kinetic mechanism for the prediction of ignition delay time and laminar flame velocity of natural gas
Yasuyuki Sakai; Yusuke Asano; Haruki Fujii; Akira Miyoshi
COMODIA2017, 2017年07月, ［査読有り］
Experimental and numerical study of the ignition delay times of primary reference fuels containing diethyl ether
M. Fikri; Y. Sakai; J. Herzler; C. Schulz
ICDERS2017, 2017年07月, ［査読有り］
A computational kinetics study on the intramolecular hydrogen shift reactions of alkylperoxy radicals in 2-methyltetrahydrofuran oxidation
Prajakta R. Parab; Naoki Sakade; Yasuyuki Sakai; Ravi Fernandes; K. Alexander Heufer
Int. J. Chem. Kinet., 2017年03月, ［査読有り］
詳細反応機構の解読にもとづくノルマルトリデカンの簡略化反応機構の構築
桑原 一成; 松尾 直; 酒井 康行; 小橋 好充; 堀 司; 松村 恵理子; 千田 二郎
自動車技術会論文集, 2017年01月, ［査読有り］
A quantum chemical and kinetics modeling study on the autoignition mechanism of diethyl etherYasuyuki Sakai; Juergen Herzler; Marc Werler; Christof Schulz; Mustapha Fikri, A detailed chemical kinetics model has been developed to elucidate the auto-ignition behavior of diethyl ether (DEE) under conditions relevant for internal combustion engines. The present model is composed of a C-0-C-4 base module from literature and a DEE module. For the low-temperature oxidation mechanism, the reactions of ROO and QOOH radicals were studied previously with a quantum-chemical and transition state theory approach by Sakai et al. (2015). In the present study, the potential energy surfaces for the unimolec-ular reactions of OOQOOH isomers and 1-and 2-ethoxyethyl radicals were determined with a CBSQB3 composite method. In the presence of an OOH group, the reaction barrier of the hydrogen shift from the beta site (terminal carbon atom) decreases as it does in alkane oxidation but there is no effect on the hydrogen shift from the alpha site (next to the ether oxygen atom). Therefore, the reaction barriers of OOQOOH isomers have the same trend as the corresponding ROO radical and rate constants for the reactions of OOQOOH isomers were determined. The constructed model was validated against the recent data of ignition delay times provided in literature by Werler et al. (2015). The agreement is good over the temperature range 500-1300 K and pressure range 1-40 bar, although, open questions remain regarding the non-consensus at 900-1150 K and 40 bar. Reaction-path and sensitivity analyses attribute the importance of the reactivity at the alpha site to the decrease of the C H bond dissociation energy due to the ether oxygen atom. (C) 2016 by The Combustion Institute. Published by Elsevier Inc., ELSEVIER SCIENCE INC
PROCEEDINGS OF THE COMBUSTION INSTITUTE, 2017年,
［査読有り］ A study on knocking prediction improvement using chemical reaction calculation
Taizo Kitada; Masato Kuchita; Shinji Hayashi; Takayuki Shirota; Yasuyuki Sakai; Hiromitsu Kawazoe
SAE Int. J. Engines, 2016年04月, ［査読有り］
化学反応速度論にもとづくオクタン価リファレンス燃料の着火遅れ式（第2報） - 低温酸化反応を経由する低温条件の着火過程 -
桑原 一成; 多田 卓矢; 古谷 正広; 小橋 好充; 酒井 康行; 松村 恵理子; 千田 二郎
自動車技術会論文集, 2016年01月, ［査読有り］
Reduction of Reaction Mechanism for n -Tridecane Based on Knowledge of Detailed Reaction PathsKazunari Kuwahara; Tadashi Matsuo; Yasuyuki Sakai; Yoshimitsu Kobashi; Tsukasa Hori; Eriko Matsumura; Jiro Senda, n-Tridecane is a low boiling point component of gas oil, and has been used as a single-component fuel for diesel spray and combustion experiments. However, no reduced chemical kinetic mechanisms for n-tridecane have been presented for three-dimensional modeling. A detailed mechanism developed by KUCRS (Knowledge-basing Utilities for Complex Reaction Systems), contains 1493 chemical species and 3641 reactions. Reaction paths during ignition process for n-tridecane in air computed using the detailed mechanism, were analyzed with the equivalence ratio of 0.75 and the initial temperatures of 650 K, 850 K, and 1100 K, which are located in the cool-flame dominant, negative-temperature coefficient, and blue-flame dominant regions, respectively. Based on knowledge derived from the reaction path analysis, a skeletal mechanism containing 49 species and 85 reactions, was developed and validated for representing ignition characteristics over a wide range of initial conditions computed using the detailed mechanism. The skeletal mechanism includes C3H7, C2H5, and CH3 as representative fragmental alkyl radicals, C7H14, C3H6, and C2H4 as representative alkenes, and C3H7CHO and CH2O as representative aldehydes. C3-series reactions beginning with O2 addition to C3H7, were expressed using parameters for C6-series reactions, which took similar reactions for larger alkyl radicals into consideration. Ignition delay times and low-temperature oxidation induction times with the initial temperatures between 600 K and 1200 K using the skeletal mechanism, and their dependences on pressure and equivalence ratio in lean and stoichiometric cases agree well with those using the detailed mechanism. However, the agreement becomes worse as equivalence ratio is increased in rich cases., SAE International
SAE Technical Papers, 2016年,
［査読有り］ Theoretical investigation of intramolecular hydrogen shift reactions in 3-methyltetrahydrofuran (3-MTHF) oxidation
Prajakta Rajaram Parab; Naoki Sakade; Yasuyuki Sakai; Ravi Xavier Fernandes; Karl Alexander Heufer
J. Phys. Chem. A, 2015年12月, ［査読有り］
Heat Release Rate and Cylinder Gas Pressure Oscillation in Low and High Speed KnockHiromitsu Ando; Atsushi Nishiyama; Yoshihiro Wachi; Kazunari Kuwahara; Yasuyuki Sakai; Takashi Ohta, One of the authors has proposed to use the decay rate of EHRR, the effective heat release rate, d2Q/dδ2 as an index for the rapid local combustion [1]. In this study, EHRR profiles and the cylinder gas pressure oscillations of the low and high speed knock are analyzed by using this index. A delayed rapid local combustion, such as an autoignition with small burned mass fraction can be detected. In the cases of the low speed knock, it has been agreed that a rapid local combustion is an autoignition. Although whether the cylinder gas oscillation is provoked by an auto ignition in a certain cycle or not is an irregular phenomenon, the auto ignition takes place in almost all of the cycles in the knocking condition. Mixture mass fraction burned by an auto ignition is large. A small auto ignition may induce a secondary auto ignition, in many cases, mass burned by the secondary auto ignition is extremely large. On the other hand, in the cases of the high speed knock, it has not been confirmed that the rapid local combustion is an auto ignition. An intense cylinder gas pressure oscillation is provoked in most of the cycles in the knocking condition, and standing wave at the edges in combustion chamber, may induce a cylinder gas pressure oscillation even in the non-knocking cycles. A mixture mass fraction burned by a rapid local combustion seems to be small and give no influence to the EHRR profile., SAE International
SAE Technical Papers, 2015年09月,
［査読有り］ Chemical Kinetics Based Equations for Ignition Delay Times of Primary Reference Fuels Dependent on Fuel, O2 and Third Body Concentrations and Heat CapacityMasaki Natakani; Kazunari Kuwahara; Takuya Tada; Yasuyuki Sakai; Hiromitsu Ando, The ignition delay times of n-C7H16, i-C8H18, and a blend of them at different fuel, O2 and N2 concentrations were computed using a detailed chemical kinetic mechanism generated by KUCRS. For each fuel, the dependences of ignition delay time on fuel, O2 and third body concentrations and on the heat capacity of a mixture were distilled to establish a power law equation for ignition delay time. For n-C7H16, ignition delay time Δhigh without low-temperature oxidation at a high initial temperature between 1000 K and 1200 K was expressed using the scaling exponents for fuel, O2 and third body concentrations and heat capacity of 0.54, 0.29, 0.08, and - 0.38, respectively. Low-temperature oxidation induction time Δ1 at a low initial temperature between 600 K and 700 K was expressed using the scaling exponents for fuel, O2 and third body concentrations and heat capacity of 0.03, 0.18, 0.04, and - 0.17, respectively. Total ignition delay time with low-temperature oxidation was expressed as Δlow = B·(Δhigh - Δ1) + Δ1 using extrapolated Δhigh and Δ1. B was expressed as an exponential function dependent on fuel, O2 and third body concentrations and the heat capacity of a mixture, or set for 1 when initial temperature was higher than a high-temperature limit for low-temperature oxidation, which was also dependent on fuel, O2 and third body concentrations and the heat capacity of a mixture. The equations for Δhigh and Δlow successfully estimated the ignition delay time computed using the detailed chemical kinetic mechanism., SAE International
SAE Technical Papers, 2015年09月,
［査読有り］ Classification of the Reactivity of Alkylperoxy Radicals by Using a Steady-State AnalysisYasuyuki Sakai; Daisuke Nakayama; Yusuke Asano; Kazunari Kuwahara; Akira Miyoshi; Hiromitsu Ando, To execute the computational fluid dynamics coupling with fuel chemistry in internal combustion engines, simplified chemical kinetic models which capture the low-temperature oxidation kinetics would be required. A steady-state analysis was applied to see the complicated reaction mechanism of alkylperoxy radicals by assuming the steady state for hydroperoxyalkyl (QOOH) and hydroperoxyalkylperoxy (OOQOOH) radicals. This analysis clearly shows the systematic trend of the reaction rate for the chain-branching and non-branching process of alkylperoxy (ROO) radicals as a function of the chain length and the carbon class. These trends make it possible to classify alkylperoxy radicals by their chemical structures, and suggest a reduced low-temperature oxidation chemistry., SAE International
SAE Technical Papers, 2015年09月,
［査読有り］ 化学反応速度論にもとづくオクタン価リファレンス燃料の着火遅れ式 - 低温酸化反応を経由しない高温条件の着火過程 -桑原 一成; 多田 卓矢; 古谷 正広; 大嶋 元啓; 小橋 好充; 酒井 康行; 安東 弘光; 松村 恵理子; 千田 二朗, KUCRS が提供する詳細反応モデルを用いてノルマルヘプタンとイソオクタンのそれぞれについて着火遅れ式を導出する．この着火遅れ式は，着火遅れ時間の燃料濃度依存性，酸素濃度依存性，第三体濃度依存性，熱容量依存性などを分離して記述し，シリンダー内のあらゆる着火現象に適用することを想定したものである．, 公益社団法人 自動車技術会
自動車技術会論文集, 2015年09月,
［査読有り］ Ignition Characteristics of Ethane and Its Roles in Natural Gas for HCCI Engine Operation
Hiroki Tanaka; Kazunobu Kobayashi; Takahiro Sako; Yasuyuki Sakai; Masahiro Furutani; Kazunari Kuwahara
SAE Int. J. Fuels Lubr., 2015年04月, ［査読有り］
A computational study on the kinetics of unimolecular reactions of ethoxyethylperoxy radicals employing CTST and VTSTYasuyuki Sakai; Hiromitsu Ando; Harish Kumar Chakravarty; Heinz Pitsch; Ravi X. Fernandes, Diethyl ether (DEE) has favorable properties as a diesel fuel component, including its outstanding cetane number. To utilize this promising fuel, more and more knowledge on the chemical kinetics of DEE oxidation will be required. For the present article, the rate constants of unimolecular reactions of ethoxyethylperoxy radicals, which are main intermediates in the oxidation of DEE under the engine relevant conditions, have been computationally investigated and compared with those of alkanes. Geometries, vibrational frequencies, and energies of reactants, products, and transition states with pronounced barrier were calculated according to the procedure of the CBS-QB3 method. The high-pressure limiting rate constants were calculated in the temperature range of 500-2000 K by using a conventional transition state theory with hindered rotor approximation for low frequency torsional mode. The oxygen dissociation reactions have been investigated by using a variational transition state theory based on the CASPT2(7,5)/aug-cc-pvdz single point calculations at UB3LYP/CBSB7 geometries and vibrational frequencies. It was found that the oxidation pathways are equal to those of alkane oxidations, however, the rate constants are significantly different from those of alkanes due to the oxygen vicinity. The rate constants of intramolecular hydrogen shift reactions are from 3 to 8 times larger at 700 K than those of alkylic peroxy radical when the abstracted hydrogen is in the beta-position of the ether. The rate constant of beta-scission reactions for 1,5-intra-molecular hydrogen shift products of 1-ethoxyethylperoxy radial is 163 times larger at 700 K than that of alkylic hydroperoxy radical, and this reaction becomes a main reaction pathway, whereas cyclic-ether is a main product in alkane oxidation. These characteristic rate constants are given in three-parameter modified Arrhenius form for the refinement of predictive chemical kinetic models being developed. (C) 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved., ELSEVIER SCIENCE INC
PROCEEDINGS OF THE COMBUSTION INSTITUTE, 2015年,
［査読有り］ Fuel Design Concept for Robust Ignition in HCCI Engine and Its Application to Optimize Methane-Based BlendHiroki Tanaka; Shunsuke Somezawa; Takahiro Sako; Yasuyuki Sakai; Hiromitsu Ando; Kazunari Kuwahara, A fuel design concept for an HCCI engine based on chemical kinetics to optimize the heat release profile and achieve robust ignition was proposed, and applied to the design of the optimal methane-based blend. Ignition process chemistry of each single-component of natural gas, methane, ethane, propane, n-butane and isobutane, was analyzed using detailed chemical kinetic computations. Ethane exhibits low ignitability, close to that of methane, when the initial temperature is below 800 K, but higher ignitability, close to those of propane, n-butane and isobutane, when the initial temperature is above 1100 K. Furthermore, ethane shows a higher heat release rate during the late stage of the ignition process. If the early stage of an ignition process takes place during the compression stroke, this kind of heat release profile is desirable in an HCCI engine to reduce cycle-to-cycle variation during the expansion stroke. According to results from engine operation tests using dual-component fuels with methane as the primary component and ethane, propane, n-butane and isobutane as the secondary component, methane/ethane shows a lower COV of IMEP when CA50 is set at the same timing for the expansion stroke. Furthermore, methane/ethane also shows a lower knocking intensity when CA50 is set at the same timing, close to the knocking limit, due to its lower in-cylinder pressure rise rate. These results suggest that methane/ethane can be the optimal methane-based blend for an HCCI engine to achieve both better fuel economy and higher performance by its robust ignition and high anti-knocking properties. © 2014 SAE International., SAE International
SAE International Journal of Engines, 2014年,
［査読有り］ Chemical Kinetics Study on Small-Alkane Ignition Process to Design Optimum Methane-Based Blend for HCCIKazunari Kuwahara; Takuya Tada; Hiroki Tanaka; Takahiro Sako; Masahiro Furutani; Yasuyuki Sakai; Hiromitsu Ando, The ignition delay times and heat release profiles of CH4, C2H6, C3H8, i-C4H10, and n-C4H10 and dual-component CH4-based blends with these alkanes in air were determined using a detailed chemical kinetic model. The apparent activation energy of C2H6 in the relationship between initial temperature and ignition delay time is higher than those of the other alkanes because OH formation is dominated by H2O2(+M)=OH+OH(+M) from the beginning over a wide range of initial temperatures. The heat release rate of C2H6 is higher than those of the other alkanes in the late stage of ignition delay time because H2O2 is accumulated with a higher concentration and promotes the OH formation rate of H2O2(+M)=OH+OH(+M). These ignition characteristics are reflected in those of CH4/C2H6. In an HCCI engine, misfire and partial combustion occur easily because the heat release rate during the ignition process after low-temperature OH chain branching and also during the ignition process bypassing low-temperature OH chain branching, becomes lower than the rate of decrease in internal energy during the expansion stroke. Partial combustion causes cycle-to-cycle variation in combustion as well as high HC emissions. Therefore, the heat release profile, which is slow in the early stage of ignition process, but more rapid than those of other fuels in the late stage, can reduce cycle-to-cycle variation in combustion. This type of profile is similar to that of CH4/C2H6 for an HCCI engine targeting CH4-based fuels. Copyright © 2014 SAE International., SAE International
SAE International Journal of Fuels and Lubricants, 2014年,
［査読有り］ Factors determining the octane number of alkanesHiromitsu Ando; Yasuyuki Sakai; Kazunari Kuwahara, The relationships between the octane number and the carbon atom number and the molecular structure of alkanes were comprehensively analyzed by using the detailed kinetic model generated by there automatic reaction scheme generation tool, KUCRS [1, 2]. The octane number is an index showing the ignition delay in the engine temperature regime, that is, the engine ignition temperature range. The high octane number is observed in the following two cases
1The ignition delay of the low temperature region is large.2The ignition delay of the low temperature region is the same, but the transition temperature for NTC (Negative Temperature Coefficient) region is low. Classifying the reaction path into the main path leading to the chain branching, and the four branching chain reaction prohibition paths, the reaction processes of various alkanes were analyzed
(M1-M6) Main chain branching path: RH+OH→R·ROO·→ Q·OOH→·OOQOOH→HOOPO→OPO+2OH (P1) Prohibition path 1: R•→Alkene + R′• (P2-1) Prohibition path 2-1: ROO•→Alkene + HO2 (P2-2) Prohibition path 2-2: Q•OOH→CyQO(Cyclic ether)+OH (P2-3) Prohibition path 2-3: Q•OOH→Alkene + HO2 Changes in the octane number by the molecular structure can be explained by the transition temperature to the NTC range. This process is controlled by (P1), the Prohibition path 1. The increase of the carbon number of normal alkanes enhances the contribution of (P2-2), the Prohibition path 2-2 which generates OH at the same time. The Prohibition path 2-2 shows peculiar characteristics. It attenuates (M1), the initiation reaction of the main branching chain path and it generates the branching chain carrier, OH. (P2-2), the Prohibition path 2-2 plays the predominant role in generating OH during the LTO (Low Temperature Oxidation) preparation period. When the carbon atom number is large, (P2-2), the Prohibition path 2-2 is enhanced, and OH generating rate increases, resulting in the lower octane number. Copyright © 2014 SAE International., SAE International
SAE Technical Papers, 2014年,
［査読有り］ A Computational Study on the Oxidation Reaction Pathways of Diethyl Ether in the Internal Combustion Engines
SAKAI Yasuyuki; ANDO Hiromitsu
9th Asia-Pacific Conference on Combustion, 2013年05月, ［査読有り］
Chemical Kinetcs Study on Two-Stage Main Heat Release in Ignition Process of Highly Diluted Mixtures
Kazunari Kuwahara; Takuya Tada; Masahiro Furutani; Yasuyuki Sakai; Hiromitsu Ando
SAE Technical Paper, 2013年05月, ［査読有り］
高希釈混合気の着火過程に関する化学反応論的研究
多田 卓矢; 桑原 一成; 古谷 正広; 酒井 康行; 安東 弘光
自動車技術会論文集, 2013年03月, ［査読有り］
プラズマ支援燃焼の化学反応メカニズム：プラズマサポートによる着火遅れ短縮の可能性
安東 弘光; 酒井 康行; 桑原 一成
J. Plasma Fusion Res., 2013年
Thermal decomposition of 2-phenylethanol: A computational study on mechanismYasuyuki Sakai; Hiromitsu Ando; Tatsuo Oguchi; Yoshinori Murakami, Quantum mechanical calculations for the thermal decomposition of 2-phenylethanol have been performed using the CBS-QB3 method. Based on the potential energy surfaces at the CBS-QB3 level of theory, the preferred reaction channel for the thermal decomposition of 2-phenylethanol was the six-membered cyclic rearrangement reaction and the dehydration reaction to form styrene and H2O. Further quantum chemical calculations of the subsequent reactions followed by the six-membered cyclic rearrange reaction of 2-phenylethanol were carried out and it was revealed that the barrier height for the ring opening reaction was the lowest among all of the other subsequent reactions. (C) 2012 Elsevier B. V. All rights reserved., ELSEVIER SCIENCE BV
CHEMICAL PHYSICS LETTERS, 2013年01月,
［査読有り］ Development of gasoline combustion reaction modelKohtaro Hashimoto; Mitsuo Koshi; Akira Miyoshi; Yoshinori Murakami; Tatsuo Oguchi; Yasuyuki Sakai; Hiromitsu Ando; Kentaro Tsuchiya, Gasoline includes various kinds of chemical species. Thus, the reaction model of gasoline components that includes the low-temperature oxidation and ignition reaction is necessary to investigate the method to control the combustion process of the gasoline engine. In this study, a gasoline combustion reaction model including n-paraffin, iso-paraffin, olefin, naphthene, alcohol, ether, and aromatic compound was developed. KUCRS (Knowledge-basing Utilities for Complex Reaction Systems) [1] was modified to produce paraffin, olefin, naphthene, alcohol automatically. Also, the toluene reactions of gasoline surrogate model developed by Sakai et al. [2] including toluene, PRF (Primary Reference Fuel), ethanol, and ETBE (Ethyl-tert-butyl-ether) were modified. The universal rule of the reaction mechanisms and rate constants were clarified by using quantum chemical calculation. Then, the heptane, iso-octane, 2,4,4-trimethyl-1-pentene (iso-octene), methylcyclohexane reaction model produced by KUCRS and the toluene, ethanol, and ETBE model were merged to produce gasoline surrogate master model. Chemical species and elementary reactions of the gasoline surrogate master model were reduced by using the Directed Relation Graph (DRG) method to produce 803 chemical species and 3222 reactions. To validate this reduced gasoline surrogate model, reaction calculation in the combustion chamber of a rapid compression machine (RCM) was performed. PRF, toluene/heptane mixture, and oxygenate (ethanol, ETBE) /heptane mixture were used for fuels. The comparison of experimental and calculation results of hot ignition period for RCM combustion of this study lay on a straight line. Thus, this gasoline surrogate model improved the combustion reaction under RCM combustion condition in which low-temperature oxidation process occurred. Copyright © 2013 SAE International.
SAE Technical Papers, 2013年,
［査読有り］ 低温酸化反応機構から考えるオクタン価
酒井 康行; 安東 弘光; 桑原 一成
日本燃焼学会誌, 2012年11月, ［招待有り］
Correlations Between Ignition Delay Times and Research Octane Number of Alkanes
Yasuyuki Sakai; Hiromitsu Ando; Kazunari Kuwahara; Masanori Furutani
COMODIA 2012, 2012年07月, ［査読有り］
Global Reaction Mechanism of Alkanes
Hiromitsu Ando; Yasuyuki Sakai; Kazunari Kuwahara; Masanori Furutani; Muyou Syuu
COMODIA 2012, 2012年07月, ［査読有り］
Density functional study of the phenylethyl+O2 reaction: Kinetic analysis for the low-temperature autoignition of ethylbenzenesYoshinori Murakami; Tatsuo Oguchi; Kohtaro Hashimoto; Akihiro Nakamura; Yasuyuki Sakai; Hiromitsu Ando, Quantum chemical calculations at the CBS-QB3 level of theory have been carried out to investigate the potential energy surfaces for the reactions of alpha- and beta-phenylethyl radicals with molecular oxygen. For the a-phenylethyl + O2 reaction, all of the transition states for the isomerization reactions of alpha-phenylethylperoxy radicals were positioned above the total energy of the reactants of alpha-phenylethyl + O2. For the beta-phenylethyl + O2 reaction, on the other hand, most of the transition states were positioned below the total energy of the reactants of beta-phenylethyl + O2. The RRKM rate constant analysis revealed that the backward reaction forming alpha-phenylethyl + O2 was dominant in the alpha-phenylethyl radicals + O2 reaction system at the temperature range between 300 and 1500 K, whereas the reaction pathway forming cyclic O2 structures (5b) was dominant in the beta-phenylethyl radicals + O2 reaction system at the same temperature range. In the reactions of both alpha- and beta-phenylethyl radicals with molecular oxygen, the HO2 elimination reaction channels became more and more important when the temperature increased up to around 1000 K. Further decomposition channels of the cyclic O2 structures (5b) were investigated using the density functional B3LYP theories and found that all of these decomposition reactions could proceed without any large activation barriers. The transition state structures forming such cyclic O2 structures in the phenylpropyl + O2 have also been calculated, and it was found that these cyclic O2 structures were one of the major products on the high-temperature reactions of beta- and ?-phenylpropyl radicals with molecular oxygen. (c) 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011, WILEY-BLACKWELL
INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, 2012年04月,
［査読有り］ バイオディーゼルサロゲートの着火特性に関する反応論的解析 (第3報)
平村 義浩; 大村 慎太郎; 桑原 一成; 酒井 康行; 安東 弘光
自動車技術会論文集, 2012年03月, ［査読有り］
低温酸化を経由しない場合の様々な燃料の化学反応機構
安東 弘光; 酒井 康行; 周 梦瑶; 桑原 一成
自動車技術会論文集, 2012年03月, ［査読有り］
特集：第22回内燃機関シンポジウム
飯田 訓正; 小池 誠; 小酒 英範; 調 尚孝; 津江 光洋; 飯島 晃良; 金野 満; 小川 英之; 相澤 哲哉; 酒井 康行; 伊東 明美; 佐藤 進; 島崎 勇一; 内田 登; 神田 智博
Engine Review, 2012年
Chemical kinetics study on effect of pressure and fuel, O2 and N2 molar concentrations on hydrocarbon ignition processKazunari Kuwahara; Yoshihiro Hiramura; Shintaro Ohmura; Masahiro Furutani; Yasuyuki Sakai; Hiromitsu Ando, Ignition process chemistry was analyzed using a detailed chemical kinetic model of n-heptane generated by KUCRS (Knowledge-basing Utilities for Complex Reaction Systems), wherein pressure dependent rate constants of the O 2 addition to alkyl radicals and hydroperoxy alkyl radicals and the thermal decomposition of ketohydroperoxides have been introduced. Then, the effect of the initial pressure and the individual effects of the initial fuel, O2 and N2 molar concentrations on a relationship between the initial temperature and the ignition delay were discussed. When the initial temperature increases, the branch of C7H14OOH removal into the second O2 addition and the decomposition into C 7H14cyO and OH is more sensitive to the pressure and the O2 concentration, and thus, the LTO preparation phase is more affected by the pressure and the O2 concentration. The LTO phase terminates mainly by the OH removal by intermediate species. When the pressure and the O2 concentration increase, the activated second O2 addition to C7H14OOH causes intermediate species to accumulate less efficiently, and thus, the LTO end temperature to increase. A period of the thermal ignition preparation phase is controlled by the rate of H2O2 (+ M) = OH + OH (+ M). When the pressure increases, the rate of this reaction increases by the dependence order of about 2, and due to the proportional increase in the whole gas concentration, the ignition delay shortens by the dependence order of about 1 in the blue-flame dominant region. Copyright © 2012 SAE International.
SAE Technical Papers, 2012年,
［査読有り］ OHラジカル添加による炭化水素自着火制御の可能性
安東 弘光; 酒井 康行; 深野 健太; 周 梦瑶; 桑原 一成
自動車技術会論文集, 2011年03月, ［査読有り］
LTOに同期させた火花放電による着火の促進桑原 一成; 瀬崎 貴史; 山本 洋平; 志知 宏昭; 酒井 康行; 古谷 正広; 安東 弘光; 太田 安彦, 自動車技術会
自動車技術会論文集, 2011年01月,
［査読有り］ Chemical kinetics study on ignition characteristics of biodiesel surrogatesKazunari Kuwahara; Koryu Nakahara; Yoshimitsu Wada; Jiro Senda; Yasuyuki Sakai; Hiromitsu Ando, Methyl butanoate (MB) and methyl decanoate (MD) are surrogates for biodiesel fuels. According to computational results with their detailed reaction mechanisms, MB and MD indicate shorter ignition delays than long alkanes such as n-heptane and n-dodecane do at an initial temperature over 1000 K. The high ignitability of these methyl esters was computationally analyzed by means of contribution matrices proposed by some of the authors. Due to the high acidity of an α-H atom in a carbonyl compound, hydroperoxy radicals are generated out of the equilibrium between forward and backward reactions of O2 addition to methyl ester radicals by the internal transfer of an α-H atom in the initial stage of an ignition process. Some of the hydroperoxy methyl ester radicals can generate OH to activate initial reactions. MB has an efficient CH3O formation path via CH3 generated by the β-scission of an MB radical which has a radical site on the α-C atom to the carbonyl group. MB has also other CH3O formation paths via some of fragmental oxygenated radicals. Therefore, the CH3O concentration is remarkably high in a thermal ignition preparation phase. The rich CH3O decomposes into CH2O and H, and then H combines with O2 into HO2. This exothermic reaction, H + O 2 + M = HO2 + M, plays a key role in promoting initial heat release. MD has efficient paths for initial heat release starting from the O2 addition to some of fragmental methyl ester radicals and ending in the OH formation via the internal transfer of an α-H atom. These paths considerably contribute not only to promoting initial heat release but also to generating OH in the initial stage of an ignition process. In conclusion, these mechanisms for the high ignitability are caused by a common local structure of methyl ester molecules, a carbonyl group in the molecule. © Copyright 2011 Society of Automotive Engineers of Japan, Inc. and SAE International.
SAE Technical Papers, 2011年,
［査読有り］ Lumped chemical kinetic model based on the detailed analysis of hydrocarbon fuel ignitionYasuyuki Sakai; Hiromitsu Ando; Kazunari Kuwahara, A systematic chemical lumping method has been proposed, based on the detailed kinetic analysis of hydrocarbon fuel ignitions. The model constructed by using this method contains two reaction sets, RO2 and fragment reaction package. The ignition characteristics of each fuel can be reflected by only adjusting several rate parameters in RO2 reaction package. From the comparison with detailed model, it was confirmed that this simplified model well reproduces the results of detailed one without missing the kinetics of hydrocarbon ignitions. We concluded that this new lumping approach has the possibility to be applicable to every hydrocarbon fuels. © Copyright 2011 Society of Automotive Engineers of Japan, Inc. and SAE International.
SAE Technical Papers, 2011年,
［査読有り］ HCCIエンジンへのHCHO添加が着火におよぼす影響に関する反応論的考察
安東 弘光; 酒井 康行; 桑原 一成; 古谷 正弘; 太田 安彦
自動車技術会論文集, 2010年01月, ［査読有り］
What is X in Livengood-Wu Integral?
Hiromitsu Ando; Yasuhiko Ohta; Kazunari Kuwahara; Yasuyuki Sakai
Review of Automotive Enginerring, 2009年, ［招待有り］
A kinetic modeling study on the oxidation of primary reference fuel-toluene mixtures including cross reactions between aromatics and aliphaticsYasuyuki Sakai; Akira Miyoshi; Mitsuo Koshi; William J. Pitz, A detailed chemical kinetic model for the mixtures of primary reference fuel (PRF: n-heptane and isooctane) and toluene has been proposed. This model is divided into three parts; a PRF mechanism [T. Ogura, Y. Sakai, A. Miyoshi, M. Koshi, P. Dagaut, Energy Fuels 21 (2007) 3233-3239], toluene sub-mechanism and cross reactions between PRF and toluene. Toluene sub-mechanism includes the low temperature kinetics relevant to engine conditions. A chemical kinetic mechanism proposed by Pitz et al. [W.J. Pitz, R. Seiser, J.W. Bozzelli, et al., in: Chemical Kinetic Characterization of the Combustion of Toluene, Proceedings of the Second Joint Meeting of the U.S. Sections of the Combustion Institute, 2001] was used as a starting model and modified by updating rate coefficients. Theoretical estimations of rate coefficients were performed for toluene and benzyl radical reactions important at low temperatures. Cross reactions between alkane, alkene, and aromatics were also included in order to account for the acceleration by the addition of toluene into iso-octane recently found in the shock tube study of the ignition delay [Y. Sakai, H.. Ozawa, T. Ogura, A. Miyoshi, M. Koshi, W.J. Pitz, Effects of Toluene Addition to Primary Reference Fuel at High Temperature, SAE 2007-01-4104, 2007]. Validations of the model were performed with existing shock tube and flow tube data. The model well predicts the ignition characteristics of PRF/toluene mixtures under the wide range of temperatures (500-1700 K) and pressures (2-50 atm). It is found that reactions of benzyl radical with oxygen molecule determine the reactivity of toluene at low temperature. Although the effect of toluene addition to iso-octane is not fully resolved, the reactions of alkene with benzyl radical have the possibility to account for the kinetic interactions between PRF and toluene. (C) 2009 The Combustion Institute. Published by Elsevier Inc. All rights reserved., ELSEVIER SCIENCE INC
PROCEEDINGS OF THE COMBUSTION INSTITUTE, 2009年,
［査読有り］ Universal rule of hydrocarbon oxidationHiromitsu Ando; Yasuyuki Sakai; Kazunari Kuwahara, Hydrocarbon thermal ignition in internal combustion engines is controlled by the balance of heat release rate by chemical reactions and internal energy formation or removal rate by adiabatic compression or expansion. Heat release rate can be described by a simple "Universal Rule", that the heat release rate during the thermal ignition preparation period is determined by H2O2 loop composed of four elementary reactions. This rule was validated by sensitivity analysis and response analysis to perturbation of intermediate species concentrations. The rule was applied to clarify several subjects with experimental backgrounds, such as ignition characteristics of higher octane number fuels, an old and well-known knocking model and the influence of H2 addition. Copyright © 2009 SAE International.
SAE Technical Papers, 2009年,
［査読有り］ Modeling of the oxidation of primary reference fuel in the presence of oxygenated octane improvers: Ethyl tert-butyl ether and ethanolTeppei Ogura; Yasuyuki Sakai; Akira Miyoshi; Mitsuo Koshi; Philippe Dagaut, A detailed chemical kinetic mechanism has been developed for the oxidation of primary reference fuel (PRF, mixture of n-heptane and iso-octane) in the presence of ethyl tert-butyl ether (ETBE) or ethanol. The mechanism was validated by comparison with the existing experimental data from shock tubes, a jet-stirred reactor, and a flow reactor. ETBE and ethanol are known as octane number improvers. Enhancement of research octane number (RON) by the addition of ETBE and ethanol to PRF has been measured using a cooperative fuel research (CFR) engine. Increase in RON was simulated with the present detailed kinetic mechanism by estimating the critical compression ratio (CCR) for autoignition in a motored engine. The correlation curve between CCR and RON was derived by calculating the CCR for PRF whose composition defines the RON. The kinetic model reproduces observed variations in RON by the addition of ETBE and ethanol to PRF. Those additives showed a very similar effect on RON., AMER CHEMICAL SOC
ENERGY & FUELS, 2007年11月,
［査読有り］ サロゲート燃料の燃焼反応機構とその応用
酒井 康行; 小倉 鉄平; 三好 明; 越 光男
Engine Technology, 2007年
Detailed kinetic modeling of toluene combustion over a wide range of temperature and pressureYasuyuki Sakai; Takayoshi Inamura; Teppei Ogura; Mitsuo Koshi; W. J. Pitz, The ignition delay times of toluene-oxygen-argon mixtures with fuel equivalence ratios from 0.5 to 1.5 and concentrations of toluene from 0.1 to 2.0% were measured behind reflected shock waves for temperatures 1270 to 1755 K and at a pressure of 2.4 ± 0.7 atm. A detailed chemical kinetic model has been developed on the basis of a kinetic mechanism proposed by Pitz et al. [1] to reproduce our experimental results as well as some literature data obtained in other shock tubes at pressures from 1.1 to 50 atm. It is found that the present chemical kinetic model could give better agreement on the pressure dependence of the ignition delay times than the previously proposed kinetic models. Copyright © 2007 Society of Automotive Engineers of Japan, Inc.
SAE Technical Papers, 2007年,
［査読有り］ 含酸素化合物のオクタン価向上効果に関する基礎的検討
酒井 康行; 小倉 鉄平; 越 光男; 新井 充; 金子 タカシ
自動車技術会論文集, 2006年05月, ［査読有り］
