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1

Ionization of in-cylinder charge during preflame period in compression ignition of mixtures

Furutani M., Sato M., Shichi H., Ohta Y.

Journal of KONES

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2004

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Vol. 11, No. 1-2

157-164

EN

Ion formation has been detected in cool and blue flames that appear during the preflame period of mixture ignition caused in a rapid compression machine. An ionization gap was installed in the combustion chamber. Ion current level is much lower than that of normally observed in propagation flames, but highly reproducible. Ions arise at the time the cool flame degenerates, and again in the blue-flame induction time T2. Breakdown of electric non-conductance during the preflame period has been investigated recently using a motored premixed-compression ignition engine. An electrode gap was installed in the combustion chamber. Between the electrodes a high static voltage of 2 200 V was given, charged in a small capacitor. It has been found that the timing of discharge or break down during the preflame period was the time in which the cool flame began to appear. Several attempts have been made to detect ionization of low-temperature flames produced by piston compression or on a flat burner, and to obtain advanced knowledge on the role the low-temperature reactions, which perform for the onset of final hot-flame ignition.

2

Formaldehyde for the premixed compression-ignition engine - an additive for ignition-timing control -

Yamaya Y, Furutani M., Ohta Y.

Journal of KONES

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2002

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Vol. 9, No. 1-2

291-297

EN

Lean fuel/air mixtures with various fuel/fuel ratios between methane and n-butane were supplied to a premixed compression-ignition engine (i.e. homogeneous charge compression ignition engine, HCCI) with or without supplementary gaseous formaldehyde induction as an ignition controlling additive. In the no additive case the methane and butane function as the two fuels in the high/low-octane two-fuel premixed compression-ignition operation we proposed previously as another ignition control procedure. The formaldehyde addition to the methane/ butane/air mixtures has given the engine desired and stable ignition timings controllable by the amount of formaldehyde to be added, almost independent on the fuel/fuel ratios between methane and butane. The efficacy of formaldehyde has been confirmed as an ignition controlling medium for the piston-compression ignition of hydrocarbon/air mixtures.

3

A key to achieve ignition carbon monoxide generation/consumption in blue-flame period during hydrocarbon compression ignition

Furutani M., Ohta Y., Nose M.

Journal of KONES

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2001

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Vol. 8, No. 1-2

1-8

EN

A criterion between success and failure of marginal fuel/air compression ignition was searched for using a rapid compression machine. A barely achieved ignition process was compared to a case no ignition was established due to a slightly insufficient compression pressure level. The differential on the chemical species histories during the induction periods between both cases was examined by continual different-timing gas samplings. A distinguished difference could be found only on the carbon-monoxide/carbon-dioxide ratio between the flammable and nonflammable critical conditions. The ratio increased continuously in the ignition success cases. There were no differences in other species concentration, such as gaseous water, hydrogen, formaldehyde and ethylene . At the time just before the final hot-flame onset the carbon-monoxide concentration came up to around 7 000 ppm, independent of the mixture strength. A steady carbon-monoxide/carbon-dioxide ratio was observed in the case no hot-flame onset was established. Continuous growing of carbon monoxide during the blue-flame period would be an indication for the transfer to the final hot-flame ignition.