Combustion Development to Realize High Thermal Efficiency Engines

Takahashi, Daishi; Nakata, Kohei; Yoshihara, Yasushi; Omura, Tetsuo

doi:10.4271/2016-01-0693

Cited by 35 publications

(17 citation statements)

References 7 publications

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“…Internal combustion engines worldwide regulations have become more and more stringent, forcing to decrease the amount of pollutant emissions and, at the same time, to increase the thermal efficiency [1]. In literature many studies report the efforts to deal with these two aspects [2][3][4]. As for spark ignition (SI) engines, engine research community and manufacturers agree in considering a 45% brake thermal efficiency a feasible goal [5], ascertained that boosting, lean combustion and high EGR dilution are mandatory.…”

Section: Introductionmentioning

confidence: 99%

Optical and Energetic Investigation of an Advanced Corona Ignition System in a Pressure-Based Calorimeter

et al. 2020

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In recent years, radio-frequency corona igniters have been extensively studied for their capability to ensure an effective ignition also in lean or diluted mixtures. Corona ignition is volumetric, with streamers coming from a star-shaped electrode. During the discharge, many radicals and excited species, able to speed up the combustion onset, are generated. At the same time, corona igniters are able to release a considerable amount of thermal energy inside the combustion chamber. The correct determination of such energy is crucial to evaluate the effectiveness of the ignition. In this work, corona discharge is experimentally evaluated inside an optical vessel. In this apparatus, the released thermal energy is measured by means of pressure-based calorimetry, and at the same time the natural luminosity of the streamers is recorded with a high-speed camera. The goal is to find a relationship between thermal energy release and streamers luminosity. Tests are performed using nitrogen as medium, at different pressure levels inside the vessel. The peak electrode voltage is varied to characterize the igniter behaviour in different operating conditions. The results of this work can be used to quantify the corona ignition capabilities to involve a wide amount of medium while releasing a high amount of thermal energy. A repeatability evaluation of streamer evolution is investigated as well.

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Section: Introductionmentioning

confidence: 99%

Optical and Energetic Investigation of an Advanced Corona Ignition System in a Pressure-Based Calorimeter

et al. 2020

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“…Intensifying in-cylinder turbulence through flows such as swirl, squish, and tumble could promote flame propagation and shorten combustion process. 2,10…”

Section: Introductionmentioning

confidence: 99%

Multi-point micro-flame ignited hybrid lean-burn combustion of gasoline with direct injection dimethyl ether

et al. 2019

International Journal of Engine Research

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Lean-burn combustion is effective in reducing fuel consumption of gasoline engines because of the higher specific heat ratio of the fuel lean mixture and reduced heat loss from lower combustion temperature. However, its application to real engines is hampered by the unstable ignition, high cyclic variability, and partial-burn due to slower combustion, as well as the restricted maximum lean-burn air/fuel ratio limit and the insufficiently low nitrogen oxides emission. Multi-point micro-flame-ignited hybrid combustion has been proposed and applied to extend the lean burn limit of premixed gasoline and air mixture. To achieve micro-flame-ignited combustion in premixed lean gasoline mixture formed by port fuel injection, a small amount of dimethyl ether is injected directly into the cylinder of a four-stroke gasoline engine to control and accelerate the ignition and combustion process so that the engine could be operated with the overall excess air coefficient (Lambda) of 1.9. The results show that heat release processes can be grouped into three forms, that is, ramp type, double-peak type, and trapezoid type. Regardless of single or split injections, direct injection timing of dimethyl ether dominates the features of heat release. The ramp type occurs at early injection timing while the double-peak type takes place at late injection timing. Trapezoid type appears between the above two types. Dimethyl ether injection timing controls the ignition timing and has less effect on combustion duration. Single injection of dimethyl ether leads to much earlier ignition timing and slightly longer combustion duration, forming higher nitrogen oxides emissions than the split injections. Ultra-low nitrogen oxides emissions and higher thermal efficiency are achieved in the ramp type combustion compared to the other two types of combustion in both injection approaches.

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“…Although the techniques such as the lean-burn and the exhaust gas recirculation (EGR) have been proposed for improving the fuel consumption and the exhaust gas emission, they also give an increase in the combustion fluctuation. Some studies have reported that the reduced combustion fluctuation can decrease the harmful exhaust emissions and increase the fuel efficiency [10][11][12][13][14][15][16]. Consequently, it is expected to develop a new method that consider the reduction of combustion fluctuation.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of Combustion Fluctuation Reduction Using In-Cylinder Pressure Estimation in Gasoline Engine

Ichiyanagi

Anggono

Dziemińska

et al. 2018

International Journal of Industrial Research and Applied Engineering

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Gasoline engines needs to reduce its negative emission waste and raise its thermal efficiency. Previous studies have shown an improvement of engines by regulating the ignition timing and retaining the engine at certain air-to-fuel ratio. Additional development of the thermal efficiency is anticipated by reducing the oscillation of pressure due to combustion (referred to as combustion fluctuation) during each cycle. Reducing the combustion fluctuations promotes the generation of a stable combustion field and improves fuel consumption. Since the combustion fluctuations are significantly affected by the in-cylinder pressure at compression top dead center (referred to as TDC pressure), the present study proposes a method to estimate the TDC pressure in the next cycle. The estimation was conducted by measuring the in-cylinder pressure at exhaust valve opening in the given cycle. This study also developed the method to reduce the combustion fluctuations by using the TDC pressure estimation and controlling the ignition timing. In our experiments, it was found that the developed methods reduced the fluctuations of the indicated mean effective pressure (IMEP), the maximum in-cylinder pressure, and the TDC pressure by 62.1%, 51.2%, and 38.5%, respectively.

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Combustion Development to Realize High Thermal Efficiency Engines

Cited by 35 publications

References 7 publications

Optical and Energetic Investigation of an Advanced Corona Ignition System in a Pressure-Based Calorimeter

Optical and Energetic Investigation of an Advanced Corona Ignition System in a Pressure-Based Calorimeter

Multi-point micro-flame ignited hybrid lean-burn combustion of gasoline with direct injection dimethyl ether

Experimental Study of Combustion Fluctuation Reduction Using In-Cylinder Pressure Estimation in Gasoline Engine

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