Combustion Exhaust Emissions of the Spark-Assisted Methanol Diesel Engine

Seko, Toshiyuki; Yoshida, Yusaku; Yamaguchi, Ikuo; Sakai, Takayuki; Hori, Masahiko; Kim, Yong Kil

doi:10.4271/861165

Cited by 12 publications

(1 citation statement)

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“…A lot of feasibility studies of alcohol diesel were conducted extensively in the 1990s. In the history of alcohol diesel research and development, the approaching way of ignition improvement is categorized by two points of view: one is on the engine-side measures by employing ignition-assist devices such as a glow plug [1][2][3][4], spark plug [5][6][7], or heating surface [8] and the other is on the fuel-side measures by adding small amounts of the ignition improver [9,10]. Almost all of these studies just concerned to seek the optimum configurations of ignition-assist devices and amount of additives within each examined engine and their performance.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study on the Required Surrounding Gas Conditions for Stable Autoignition of an Ethanol Spray

Saitoh

Uchida

Watanabe

2019

Journal of Combustion

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This study deals with the development of controlled-ignition technology for high-performance compression ignition alcohol engines. Among the alcohol fuels, we focus on ethanol as it is a promising candidate of alternative fuels replacing petroleum. The objective of this study is to reveal the physical and chemical phenomena in the mixture formation process up to autoignition of an ethanol spray. In our previous numerical study, we showed the mixture formation process for gas oil and ethanol sprays in the form of spatial excess air ratio and temperature distributions inside a spray and their temporal histories from fuel injection. The results showed a good agreement with those of theoretical analysis based on the momentum theory of spray penetration. Calculation was also confirmed as reasonable by comparing to the experimental results. Through the series of our experimental and numerical studies, the reason for poor autoignition quality of an ethanol spray was revealed, that is, difficulty in simultaneous attainments of autoignition-suitable concentration and temperature in the spray mixture formation due to its fuel and thermal properties of smaller stoichiometric air-fuel ratio and much greater heat of evaporation compared to conventional diesel fuels. However, autoignition of an ethanol spray has not been obtained yet in either experiments or numerical analysis. As the next step, we numerically examined several surrounding gas pressure and temperature conditions to make clear the surrounding gas conditions enough to obtain stable autoignition. One of the commercial CFD codes CONVERGE was used in the computational calculation with the considerations of turbulence, atomization, evaporation, and detailed chemical reaction. Required surrounding gas pressure and temperature for stable autoignition with acceptable ignition delay of an ethanol spray and feasibility of the development of high-performance compression ignition alcohol engines are discussed in this paper.

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