A Gas Sampling Study on the Formation Processes of Soot and NO in a DI Diesel Engine

Aoyagi, Yoshinobu; Kamimoto, Takeyuki; Matsui, Yukio; Matsuoka, Satoshi

doi:10.4271/800254

Cited by 82 publications

(18 citation statements)

References 7 publications

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“…NOx formed in a DI diesel engine depends on the local oxygen atom concentration, which is a function of the concentration of oxygen molecules and local temperature. Measurement of temperature in the combustion chamber of a DI diesel engine has shown the flame temperature for diesel fuel to be slightly lower than that for the hydrogen fuel at the same equivalence ratio [16,17]. Addition of hydrogen can lead to higher local temperature earlier in the expansion process, resulting in rapid NOx formation rate for the fixed injection timing.…”

Section: Io/smentioning

confidence: 99%

Hydrogen aspiration in a direct injection type diesel engine-its effects on smoke and other engine performance parameters

Varde

Frame

1983

International Journal of Hydrogen Energy

110

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An experimental study was undertaken to investigate the possibility of reducing diesel particulates in the exhaust by aspirating small quantities of gaseous hydrogen in the intake of a diesel engine. A single cylinder, direct injection type diesel engine was used in the experiments. Hydrogen flow rates equivalent to about 10% of the total energy substantially reduced smoke emissions at part loads. At the full rated load, reduction in smoke levels was limited; this is believed to be due to the lower amounts of excess air available in the cylinder. It was found that the engine thermal efficiency was dependent on the portion of hydrogen energy, out of the total input energy, supplied to the engine. There was no significant change in the hydrocarbon emissions but oxides of nitrogen in the exhaust increased with an increase in hydrogen energy. A/F EitOpeak NOMENCLATURE air-fuel ratio (kg/kg) rate of hydrogen energy supply (KJ/s) rate to total energy supply (KJ/s) angle when peak pressure occurs (deg) fuel air equivalence ratio (q~ < 1 is lean)

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Section: Io/smentioning

confidence: 99%

Hydrogen aspiration in a direct injection type diesel engine-its effects on smoke and other engine performance parameters

Varde

Frame

1983

International Journal of Hydrogen Energy

110

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“…The reduction is probably due to further soot oxidation still taking place at later crank angles and dilution with surrounding gases. A direct gas sampling study using an old direct injection engine in the 1970s shows a soot reduction rate of nearly 1/100 from a peak value in the cylinder to the engine-out reading [35]. The test engine hired in the present study adopts higher injection pressures and a smaller orifice diameter, and this causes higher peak soot concentrations due to higher fuel injection rates during a narrower injection period and lower engine-out emissions due to enhanced soot oxidation rates due to higher turbulent mixing rates.…”

Section: Estimation Of Soot Mass Concentrationmentioning

confidence: 99%

Re-examination of the emissivity of diesel flames

Kamimoto

Murayama

2011

International Journal of Engine Research

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In the Hottel and Broughton equation, the spectral emissivity of soot in flames in the visible wavelength range is characterized by an index α = 1.39, which represents the effect of wavelength on extinction (Hottel and Broughton, 1932). In this study, the spectral specific extinction for diesel soot is examined first by focusing on soot layers sampled on a quartz window from the engine cylinder, and α = 1.38 is obtained. To examine the physics governing the value of α = 1.38, a calculation of spectral extinction is performed using the Rayleigh–Debye–Gans (RDG) theory of soot aggregate scattering with an assumption of constant refractive index. The calculated spectral extinction provides α = 1.31 close to α = 1.38, suggesting that scattering, as well as absorption, contributes largely to the spectral extinction of diesel soot. The attenuation of line-of-sight beam intensity due to out-scattering and the augmentation of the beam intensity as a result of scattering of incoming radiation from other regions are investigated using soot aggregate scattering theory. Based on this approach, a new formula of apparent spectral emissivity εa is proposed, allowing a theoretical explanation of the physical meaning of the KL factor defined in the Hottel and Broughton equation, which has remained vague for many years. Finally the two-colour flame temperature and the KL factor in a production engine are calculated using the new emissivity formula and are compared with those obtained using the conventional emissivity formula. The result shows that the two-colour method using the conventional emissivity formula remains quite useful, and provides values of temperature and KL factor within 1–2 per cent of those obtained with the new emissivity formula.

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“…Based on these studies the local in-cylinder temperature and the local air-fuel ratio have been identified as the significant parameters and their influence on the NOx and soot formation has been extensively studied [12][13][14][15][16][17][18][19][20][21][22][23]. The formulations necessary for low-emission combustion have been identified on an F À T, or (1/F) À T, diagram such as the one indicated in Fig.…”

Section: Introductionmentioning

confidence: 99%

Implementation of multiple-pulse injection strategies to enhance the homogeneity for simultaneous low-NOx and -soot diesel combustion

Zheng

Kumar

2009

International Journal of Thermal Sciences

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A Gas Sampling Study on the Formation Processes of Soot and NO in a DI Diesel Engine

Cited by 82 publications

References 7 publications

Hydrogen aspiration in a direct injection type diesel engine-its effects on smoke and other engine performance parameters

Hydrogen aspiration in a direct injection type diesel engine-its effects on smoke and other engine performance parameters

Re-examination of the emissivity of diesel flames

Implementation of multiple-pulse injection strategies to enhance the homogeneity for simultaneous low-NOx and -soot diesel combustion

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